1.
Pesticide
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Pesticides are substances that are meant to control pests or weeds. The most common of these are herbicides which account for approximately 80% of all pesticide use, most pesticides are intended to serve as plant protection products, which in general, protect plants from weeds, fungi, or insects. In general, a pesticide is a chemical or biological agent that deters, incapacitates, kills, or otherwise discourages pests. Target pests can include insects, plant pathogens, weeds, mollusks, birds, mammals, fish, nematodes, although pesticides have benefits, some also have drawbacks, such as potential toxicity to humans and other species. According to the Stockholm Convention on Persistent Organic Pollutants,9 of the 12 most dangerous, the term includes substances intended for use as a plant growth regulator, defoliant, desiccant, or agent for thinning fruit or preventing the premature fall of fruit. Also used as substances applied to either before or after harvest to protect the commodity from deterioration during storage. Pesticides can be classified by target organism, chemical structure, biopesticides include microbial pesticides and biochemical pesticides. Plant-derived pesticides, or botanicals, have been developing quickly and these include the pyrethroids, rotenoids, nicotinoids, and a fourth group that includes strychnine and scilliroside. Many pesticides can be grouped into chemical families, prominent insecticide families include organochlorines, organophosphates, and carbamates. Organochlorine hydrocarbons could be separated into dichlorodiphenylethanes, cyclodiene compounds, and they operate by disrupting the sodium/potassium balance of the nerve fiber, forcing the nerve to transmit continuously. Their toxicities vary greatly, but they have phased out because of their persistence. Organophosphate and carbamates largely replaced organochlorines, both operate through inhibiting the enzyme acetylcholinesterase, allowing acetylcholine to transfer nerve impulses indefinitely and causing a variety of symptoms such as weakness or paralysis. Organophosphates are quite toxic to vertebrates, and have in some cases replaced by less toxic carbamates. Thiocarbamate and dithiocarbamates are subclasses of carbamates, prominent families of herbicides include phenoxy and benzoic acid herbicides, triazines, ureas, and Chloroacetanilides. Phenoxy compounds tend to selectively kill broad-leaf weeds rather than grasses, the phenoxy and benzoic acid herbicides function similar to plant growth hormones, and grow cells without normal cell division, crushing the plants nutrient transport system. Many commonly used pesticides are not included in these families, including glyphosate, Pesticides can be classified based upon their biological mechanism function or application method. Most pesticides work by poisoning pests, a systemic pesticide moves inside a plant following absorption by the plant. With insecticides and most fungicides, this movement is usually upward and outward, increased efficiency may be a result
2.
Tanzania
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Tanzania /ˌtænzəˈniːə/, officially the United Republic of Tanzania, is a country in Eastern Africa within the African Great Lakes region. Parts of the country are in Southern Africa, Mount Kilimanjaro, Africas highest mountain, is in northeastern Tanzania. Tanzanias population of 51.82 million is diverse, composed of ethnic, linguistic. Dar es Salaam, the capital, retains most government offices and is the countrys largest city, principal port. Tanzania is a one party dominant state with the Chama Cha Mapinduzi party in power, from its formation until 1992, it was the only legally permitted party in the country. Elections for president and all National Assembly seats were last held in October 2015, the CCM holds approximately 75% of the seats in the assembly. Prehistoric population migrations include Southern Cushitic speakers, who are ancestral to the Iraqw, Gorowa, and Burunge and who moved south from Ethiopia into Tanzania. Based on linguistic evidence, there may also have two movements into Tanzania of Eastern Cushitic people at about 4,000 and 2,000 years ago. These movements took place at about the time as the settlement of the iron-making Mashariki Bantu from West Africa in the Lake Victoria. They brought with them the west African planting tradition and the staple of yams. They subsequently migrated out of these regions across the rest of Tanzania, European colonialism began in mainland Tanzania during the late 19th century when Germany formed German East Africa, which gave way to British rule following World War I. The mainland was governed as Tanganyika, with the Zanzibar Archipelago remaining a separate colonial jurisdiction, following their respective independence in 1961 and 1963, the two entities merged in April 1964 to form the United Republic of Tanzania. Tanzania is mountainous and densely forested in the northeast, where Mount Kilimanjaro is located, three of Africas Great Lakes are partly within Tanzania. To the north and west lie Lake Victoria, Africas largest lake, and Lake Tanganyika, the eastern shore is hot and humid, with the Zanzibar Archipelago just offshore. The Menai Bay Conservation Area is Zanzibars largest marine protected area, over 100 different languages are spoken in Tanzania, making it the most linguistically diverse country in East Africa. Among the languages spoken in Tanzania are all four of Africas language families, Bantu, Cushitic, Nilotic, Swahili and English are Tanzanias official languages. In connection with his Ujamaa social policies, President Nyerere encouraged the use of Swahili, approximately 10% of Tanzanians speak Swahili as a first language, and up to 90% speak it as a second language. Most Tanzanians thus speak both Swahili and a language, many educated Tanzanians are trilingual, also speaking English
3.
Insect
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Insects are a class of hexapod invertebrates within the arthropod phylum that have a chitinous exoskeleton, a three-part body, three pairs of jointed legs, compound eyes and one pair of antennae. They are the most diverse group of animals on the planet, including more than a million described species, the number of extant species is estimated at between six and ten million, and potentially represent over 90% of the differing animal life forms on Earth. Insects may be found in all environments, although only a small number of species reside in the oceans. The life cycles of insects vary but most hatch from eggs, insect growth is constrained by the inelastic exoskeleton and development involves a series of molts. The immature stages can differ from the adults in structure, habit and habitat, Insects that undergo 3-stage metamorphosis lack a pupal stage and adults develop through a series of nymphal stages. The higher level relationship of the Hexapoda is unclear, fossilized insects of enormous size have been found from the Paleozoic Era, including giant dragonflies with wingspans of 55 to 70 cm. The most diverse insect groups appear to have coevolved with flowering plants, adult insects typically move about by walking, flying or sometimes swimming. As it allows for rapid yet stable movement, many insects adopt a tripedal gait in which they walk with their legs touching the ground in alternating triangles, Insects are the only invertebrates to have evolved flight. Many insects spend at least part of their lives under water, with adaptations that include gills. Some species, such as water striders, are capable of walking on the surface of water, Insects are mostly solitary, but some, such as certain bees, ants and termites, are social and live in large, well-organized colonies. Some insects, such as earwigs, show maternal care, guarding their eggs, Insects can communicate with each other in a variety of ways. Male moths can sense the pheromones of female moths over great distances, other species communicate with sounds, crickets stridulate, or rub their wings together, to attract a mate and repel other males. Lampyridae in the beetle order communicate with light, humans regard certain insects as pests, and attempt to control them using insecticides and a host of other techniques. Some insects damage crops by feeding on sap, leaves or fruits, a few parasitic species are pathogenic. Some insects perform complex ecological roles, blow-flies, for example, help consume carrion, Many other insects are considered ecologically beneficial as predators and a few provide direct economic benefit. Silkworms and bees have been used extensively by humans for the production of silk and honey, in some cultures, people eat the larvae or adults of certain insects. Insect first appears documented in English in 1601 in Hollands translation of Pliny, translations of Aristotles term also form the usual word for insect in Welsh, Serbo-Croatian, Russian, etc. The evolutionary relationship of insects to other animal groups remains unclear, in the Pancrustacea theory, insects, together with Entognatha, Remipedia, and Cephalocarida, make up a natural clade labeled Miracrustacea
4.
Larvicide
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A larvicide is an insecticide that is specifically targeted against the larval life stage of an insect. Their most common use is against mosquitoes, larvicides may be contact poisons, stomach poisons, growth regulators, or biological control agents. The biological control agent Bacillus thuringiensis, also known as Bt, is a disease specific to Lepidopteran caterpillars. Bacillus thuringiensis israelensis, also known as Bti, and Bacillus sphaericus, Bti and B. sphaericus are both naturally occurring soil bacterium registered as larvicides under the names Aquabac, Teknar, Vectobac, LarvX, and VectoLex CG. Typically in granular form, pellets are distributed on the surface of stagnant water locations, when the mosquito larvae ingest the bacteria, crystallized toxins are produced that destroy the digestive tract, resulting in death. These larvicides will last only a few weeks in water and pose no danger to humans, non-targeted animal species, methoprene is an insect growth regulator agent that interrupts the growth cycle of insect larvae, preventing them from development beyond the pupa stage. MetaLarv and Altosid are products containing S-methoprene as the active ingredient and they are usually applied to larger bodies of water in the form of time-release formulations that can last from one to five months. Use of this larvicide does not pose an unreasonable health risks to humans or other wildlife, methoprene is moderately toxic to some fish, shrimp, lobster, and crayfish, and highly toxic to some fish and freshwater invertebrates, it bioaccumulates in fish tissues. Temephos, marketed as Abate and ProVect, is an organophosphate which prevents mosquito larvae from developing resistance to bacterial larvicides, similarly, there is not a large risk to terrestrial species, but there is a toxic concern for non-targeted aquatic species. Therefore, temephos should be limited only to sites where less hazardous larvicides are ineffective, research on botanical oils has found neem oil to be larvicidal. Larvicidal activity of neem oil formulation against mosquitoes, median lethal concentration of the formulation against Anopheles stephensi, Culex quinquefasciatus and Aedes aegypti was found to be 1.6,1.8 and 1.7 ppm respectively. The formulation also showed 95. 1% and,99. 7% reduction of Aedes larvae on day 1 and day 2 respectively, index of pesticide articles EPA explanations of various larvicides
5.
Egg
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An egg is the organic vessel containing the zygote in which an animal embryo develops until it can survive on its own, at which point the animal hatches. An egg results from fertilization of an ovum, most arthropods, vertebrates, and mollusks lay eggs, although some do not, such as scorpions and most mammals. Reptile eggs, bird eggs, and monotreme eggs are laid out of water, eggs laid on land or in nests are usually kept within a favorable temperature range while the embryo grows. When the embryo is developed it hatches, i. e. breaks out of the eggs shell. Some embryos have an egg tooth with which to crack, pip. The largest recorded egg is from a shark, and was 30 cm ×14 cm ×9 cm in size. At 1.5 kg and up to 17.8 cm ×14 cm, the bee hummingbird produces the smallest known bird egg, which weighs half of a gram. The eggs laid by some reptiles and most fish can be smaller. Reproductive structures similar to the egg in other kingdoms are termed spores, or in spermatophytes seeds, several major groups of animals typically have readily distinguishable eggs. The most common strategy for fish is known as oviparity. Typically large numbers of eggs are laid at one time and the eggs are left to develop without parental care. When the larvae hatch from the egg, they carry the remains of the yolk in a yolk sac which continues to nourish the larvae for a few days as they learn how to swim. Once the yolk is consumed, there is a point after which they must learn how to hunt. A few fish, notably the rays and most sharks use ovoviviparity in which the eggs are fertilized, however the larvae still grow inside the egg consuming the eggs yolk and without any direct nourishment from the mother. The mother then gives birth to relatively mature young, in certain instances, the physically most developed offspring will devour its smaller siblings for further nutrition while still within the mothers body. This is known as intrauterine cannibalism, the eggs of fish and amphibians are jellylike. Cartilagenous fish eggs are fertilized internally and exhibit a variety of both internal and external embryonic development. Most fish species spawn eggs that are fertilized externally, typically with the male inseminating the eggs after the female lays them and these eggs do not have a shell and would dry out in the air
6.
Larva
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A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a phase of their life cycle. The larvas appearance is very different from the adult form. A larva often has unique structures and organs that do not occur in the adult form and their diet may also be considerably different. Larvae are frequently adapted to separate from adults. For example, some such as tadpoles live almost exclusively in aquatic environments. By living in an environment, larvae may be given shelter from predators. Animals in the stage will consume food to fuel their transition into the adult form. In some species like barnacles, adults are immobile but their larvae are mobile, some larvae are dependent on adults to feed them. In many eusocial Hymenoptera species, the larvae are fed by female workers, in Ropalidia marginata the males are also capable of feeding larvae but they are much less efficient, spending more time and getting less food to the larvae. The larvae of species can become pubescent and do not develop further into the adult form. This is a type of neoteny and it is a misunderstanding that the larval form always reflects the groups evolutionary history. This could be the case, but often the stage has evolved secondarily. In these cases the form may differ more than the adult form from the groups common origin. Within Insects, only Endopterygotes show different types of larvae, several classifications have been suggested by many entomologists, and following classification is based on Antonio Berlese classification in 1913. There are four types of endopterygote larvae types, Apodous larvae - no legs at all and are poorly sclerotized. Based on sclerotization, three forms are recognized. Eucephalous - with well sclerotized head capsule, found in Nematocera, Buprestidae and Cerambycidae families
7.
Agriculture
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Agriculture is the cultivation and breeding of animals, plants and fungi for food, fiber, biofuel, medicinal plants and other products used to sustain and enhance human life. Agriculture was the key development in the rise of human civilization. The study of agriculture is known as agricultural science, the history of agriculture dates back thousands of years, and its development has been driven and defined by greatly different climates, cultures, and technologies. Industrial agriculture based on large-scale monoculture farming has become the dominant agricultural methodology, genetically modified organisms are an increasing component of agriculture, although they are banned in several countries. Agricultural food production and water management are increasingly becoming global issues that are fostering debate on a number of fronts, the major agricultural products can be broadly grouped into foods, fibers, fuels, and raw materials. Specific foods include cereals, vegetables, fruits, oils, meats, fibers include cotton, wool, hemp, silk and flax. Raw materials include lumber and bamboo, other useful materials are also produced by plants, such as resins, dyes, drugs, perfumes, biofuels and ornamental products such as cut flowers and nursery plants. The word agriculture is a late Middle English adaptation of Latin agricultūra, from ager, field, Agriculture usually refers to human activities, although it is also observed in certain species of ant, termite and ambrosia beetle. To practice agriculture means to use resources to produce commodities which maintain life, including food, fiber, forest products, horticultural crops. This definition includes arable farming or agronomy, and horticulture, all terms for the growing of plants, even then, it is acknowledged that there is a large amount of knowledge transfer and overlap between silviculture and agriculture. In traditional farming, the two are often combined even on small landholdings, leading to the term agroforestry, Agriculture began independently in different parts of the globe, and included a diverse range of taxa. At least 11 separate regions of the Old and New World were involved as independent centers of origin, wild grains were collected and eaten from at least 105,000 years ago. Pigs were domesticated in Mesopotamia around 15,000 years ago, rice was domesticated in China between 13,500 and 8,200 years ago, followed by mung, soy and azuki beans. Sheep were domesticated in Mesopotamia between 13,000 and 11,000 years ago. From around 11,500 years ago, the eight Neolithic founder crops, emmer and einkorn wheat, hulled barley, peas, lentils, bitter vetch, chick peas and flax were cultivated in the Levant. Cattle were domesticated from the aurochs in the areas of modern Turkey. In the Andes of South America, the potato was domesticated between 10,000 and 7,000 years ago, along with beans, coca, llamas, alpacas, sugarcane and some root vegetables were domesticated in New Guinea around 9,000 years ago. Sorghum was domesticated in the Sahel region of Africa by 7,000 years ago, cotton was domesticated in Peru by 5,600 years ago, and was independently domesticated in Eurasia at an unknown time
8.
Medicine
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Medicine is the science and practice of the diagnosis, treatment, and prevention of disease. The word medicine is derived from Latin medicus, meaning a physician, Medicine encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness. Medicine has existed for thousands of years, during most of which it was an art frequently having connections to the religious and philosophical beliefs of local culture. For example, a man would apply herbs and say prayers for healing, or an ancient philosopher. In recent centuries, since the advent of modern science, most medicine has become a combination of art, while stitching technique for sutures is an art learned through practice, the knowledge of what happens at the cellular and molecular level in the tissues being stitched arises through science. Prescientific forms of medicine are now known as medicine and folk medicine. They remain commonly used with or instead of medicine and are thus called alternative medicine. For example, evidence on the effectiveness of acupuncture is variable and inconsistent for any condition, in contrast, treatments outside the bounds of safety and efficacy are termed quackery. Medical availability and clinical practice varies across the world due to differences in culture. In modern clinical practice, physicians personally assess patients in order to diagnose, treat, the doctor-patient relationship typically begins an interaction with an examination of the patients medical history and medical record, followed by a medical interview and a physical examination. Basic diagnostic medical devices are typically used, after examination for signs and interviewing for symptoms, the doctor may order medical tests, take a biopsy, or prescribe pharmaceutical drugs or other therapies. Differential diagnosis methods help to rule out conditions based on the information provided, during the encounter, properly informing the patient of all relevant facts is an important part of the relationship and the development of trust. The medical encounter is then documented in the record, which is a legal document in many jurisdictions. Follow-ups may be shorter but follow the general procedure. The diagnosis and treatment may take only a few minutes or a few weeks depending upon the complexity of the issue, the components of the medical interview and encounter are, Chief complaint, the reason for the current medical visit. They are in the patients own words and are recorded along with the duration of each one, also called chief concern or presenting complaint. History of present illness, the order of events of symptoms. Distinguishable from history of illness, often called past medical history
9.
Industry
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Industry is the production of goods or related services within an economy. The major source of revenue of a group or company is the indicator of its relevant industry, when a large group has multiple sources of revenue generation, it is considered to be working in different industries. Manufacturing industry became a key sector of production and labour in European and North American countries during the Industrial Revolution, upsetting previous mercantile and this came through many successive rapid advances in technology, such as the production of steel and coal. Following the Industrial Revolution, possibly a third of the economic output are derived that is from manufacturing industries. Many developed countries and many developing/semi-developed countries depend significantly on manufacturing industry, Industries, the countries they reside in, and the economies of those countries are interlinked in a complex web of interdependence. Industries can be classified in a variety of ways, at the top level, industry is often classified according to the three-sector theory into sectors, primary, secondary, and tertiary. Some authors add quaternary or even quinary sectors, over time, the fraction of a societys industry within each sector changes. Below the economic sectors there are other more detailed industry classifications. These classification systems commonly divide industries according to functions and markets. Market-based classification systems such as the Global Industry Classification Standard and the Industry Classification Benchmark are used in finance, the International Standard Industrial Classification of all economic activities is the most complete and systematic industrial classification made by the United Nations Statistics Division. ISIC is a classification of economic activities arranged so that entities can be classified according to the activity they carry out. The Industrial Revolution led to the development of factories for large-scale production, originally the factories were steam-powered, but later transitioned to electricity once an electrical grid was developed. The mechanized assembly line was introduced to parts in a repeatable fashion. This led to significant increases in efficiency, lowering the cost of the end process, later automation was increasingly used to replace human operators. This process has accelerated with the development of the computer and the robot, historically certain manufacturing industries have gone into a decline due to various economic factors, including the development of replacement technology or the loss of competitive advantage. An example of the former is the decline in manufacturing when the automobile was mass-produced. A recent trend has been the migration of prosperous, industrialized nations towards a post-industrial society and this is manifested by an increase in the service sector at the expense of manufacturing, and the development of an information-based economy, the so-called informational revolution. In a post-industrial society, manufacturing is relocated to more favourable locations through a process of off-shoring
10.
Nicotine
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Nicotine is a potent parasympathomimetic stimulant and an alkaloid found in the nightshade family of plants. Nicotine acts as a receptor agonist at most nicotinic acetylcholine receptors, Nicotine is found in the leaves of Nicotiana rustica in amounts of 2–14%, the tobacco plant Nicotiana tabacum, Duboisia hopwoodii and Asclepias syriaca. Nicotine constitutes approximately 0. 6–3. 0% of the dry weight of tobacco, less than one millionth of that concentration is found in edible Solanaceae such as eggplants and tomatoes. It functions as a chemical, consequently, nicotine was widely used as an insecticide in the past. An average cigarette yields about 2 mg of absorbed nicotine, and in lesser doses of that order and this stimulant effect is a contributing factor to the addictive properties of tobacco smoking. Nicotines addictive nature includes psychoactive effects, drug-reinforced behavior, compulsive use, relapse after abstinence, beyond addiction, both short and long-term nicotine exposure have not been established as dangerous to adults, except among certain vulnerable groups. At high-enough doses, nicotine is associated with poisonings and is potentially lethal, Nicotine as a tool for quitting smoking has a good safety history. There is inadequate research to show that nicotine itself is associated with cancer in humans, Nicotine in the form of nicotine replacement products is less of a cancer risk than smoking. Nicotine is linked to birth defects. During pregnancy, there are risks to the later in life for type 2 diabetes, obesity, hypertension, neurobehavioral defects, respiratory dysfunction. Nicotines mood-altering effects are different by report, in particular it is both a stimulant and a relaxant, first causing a release of glucose from the liver and epinephrine from the adrenal medulla, it causes stimulation. Users report feelings of relaxation, sharpness, calmness, and alertness, like any stimulant, it may very rarely cause the often uncomfortable akathisia. By reducing the appetite and raising the metabolism, some smokers may lose weight as a consequence, Nicotine also extends the duration of positive effects of dopamine and increases the sensitivity of the brains reward system to rewarding stimuli. Most cigarettes contain 1–3 milligrams of inhalable nicotine, studies suggest that when smokers wish to achieve a stimulating effect, they take short quick puffs, which produce a low level of blood nicotine. At very high doses it dampens neuronal activity, the primary therapeutic use of nicotine is in treating nicotine dependence in order to eliminate smoking with the damage it does to health. Controlled levels of nicotine are given to patients through gums, dermal patches, lozenges, studies have found that these therapies increase the chance of success of quitting by 50 to 70%, though reductions in the population as a whole have not been demonstrated. Nicotine is frequently used for its effects on cognition, alertness. Nicotine is commonly consumed as a drug for its stimulant effects
11.
Pyrethrum
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Pyrethrum was a genus of several Old World plants now classified as Chrysanthemum or Tanacetum which are cultivated as ornamentals for their showy flower heads. Pyrethrum continues to be used as a name for plants formerly included in the genus Pyrethrum. Pyrethrum is also the name of a natural insecticide made from the flower heads of Chrysanthemum cinerariifolium and Chrysanthemum coccineum. Some members of the Chrysanthemum genus, such as the two, are placed in the Tanacetum genus instead by some botanists. Both genera are members of the family, Asteraceae. They are all perennial plants with an appearance and white petals. T. cinerariifolium is called the Dalmatian chrysanthemum, denoting its origin in that region of the Balkans and it looks more like the common daisy than other pyrethrums do. Its flowers, typically white with yellow centers, grow from numerous fairly rigid stems, plants have blue-green leaves and grow to 45 to 100 cm in height. The plant is important as a natural source of insecticide. The flowers are pulverized and the components, called pyrethrins, contained in the seed cases, are extracted. This is applied as a suspension in water or oil, or as a powder, pyrethrins attack the nervous systems of all insects, and inhibit female mosquitoes from biting. When present in less than those fatal to insects, they still appear to have an insect repellent effect. They are harmful to fish, but are far less toxic to mammals and birds than many synthetic insecticides and are not persistent, being biodegradable and they are considered to be amongst the safest insecticides for use around food. Kenya produced 90% of the worlds pyrethrum in 1998, called py for short, production in Tanzania and Ecuador is also significant. Currently the worlds major producer is Tasmania, Australia, C. coccineum, the Persian chrysanthemum, is a perennial plant native to Caucasus and looks somewhat like a daisy. It produces large white, pink or red flowers, the leaves resemble those of ferns, and the plant grows to between 30 and 60 cm in height. The flowering period is June to July in temperate climates, C. coccineum also contains insecticidal pyrethrum substances, but it is a poor source compared to C. cinerariifolium. Other species, such as C. balsamita and C. marshalli, also contain insecticidal substances, Pyrethrum has been used for centuries as an insecticide, and as a lice remedy in the Middle East
12.
Azadirachta indica
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Azadirachta indica, also known as Neem, Nimtree, and Indian Lilac is a tree in the mahogany family Meliaceae. It is one of two species in the genus Azadirachta, and is native to India and the Indian subcontinent including Nepal, Pakistan, Bangladesh and it typically is grown in tropical and semi-tropical regions. Neem trees now grow in islands located in the southern part of Iran. Its fruits and seeds are the source of neem oil, Neem is a fast-growing tree that can reach a height of 15–20 metres, and rarely 35–40 metres. It is evergreen, but in severe drought it may shed most or nearly all of its leaves, the branches are wide and spreading. The fairly dense crown is roundish and may reach a diameter of 15–20 metres in old, the neem tree is very similar in appearance to its relative, the Chinaberry. The opposite, pinnate leaves are 20–40 centimetres long, with 20 to 31 medium to dark green leaflets about 3–8 centimetres long, the terminal leaflet often is missing. The flowers are arranged in more-or-less drooping axillary panicles which are up to 25 centimetres long, the inflorescences, which branch up to the third degree, bear from 150 to 250 flowers. An individual flower is 5–6 millimetres long and 8–11 millimetres wide, protandrous, bisexual flowers and male flowers exist on the same individual tree. The fruit is a smooth, olive-like drupe which varies in shape from oval to nearly roundish. The fruit skin is thin and the pulp is yellowish-white. The mesocarp is 0. 3–0.5 centimetres thick, the white, hard inner shell of the fruit encloses one, rarely two, or three, elongated seeds having a brown seed coat. Neem is a Hindi noun derived from Sanskrit Nimba, normally it thrives in areas with sub-arid to sub-humid conditions, with an annual rainfall of 400–1,200 millimetres. It can grow in regions with an annual rainfall below 400 mm, Neem can grow in many different types of soil, but it thrives best on well drained deep and sandy soils. It is a tropical to subtropical tree and exists at annual mean temperatures of 21–32 °C. It can tolerate high to high temperatures and does not tolerate temperature below 4 °C. Neem is one of a very few shade-giving trees that thrive in drought-prone areas e. g. the dry coastal, southern districts of India, the trees are not at all delicate about water quality and thrive on the merest trickle of water, whatever the quality. In very dry areas the trees are planted on large tracts of land, Neem is considered a weed in many areas, including some parts of the Middle East, most of Sub-Saharan Africa including West Africa and Indian Ocean states, and some parts of Australia
13.
Organic compound
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An organic compound is virtually any chemical compound that contains carbon, although a consensus definition remains elusive and likely arbitrary. Organic compounds are rare terrestrially, but of importance because all known life is based on organic compounds. The most basic petrochemicals are considered the building blocks of organic chemistry, for historical reasons discussed below, a few types of carbon-containing compounds, such as carbides, carbonates, simple oxides of carbon, and cyanides are considered inorganic. The distinction between organic and inorganic compounds, while useful in organizing the vast subject of chemistry. Organic chemistry is the science concerned with all aspects of organic compounds, Organic synthesis is the methodology of their preparation. The word organic is historical, dating to the 1st century, for many centuries, Western alchemists believed in vitalism. This is the theory that certain compounds could be synthesized only from their classical elements—earth, water, air, vitalism taught that these organic compounds were fundamentally different from the inorganic compounds that could be obtained from the elements by chemical manipulation. Vitalism survived for a while even after the rise of modern atomic theory and it first came under question in 1824, when Friedrich Wöhler synthesized oxalic acid, a compound known to occur only in living organisms, from cyanogen. A more decisive experiment was Wöhlers 1828 synthesis of urea from the inorganic salts potassium cyanate, urea had long been considered an organic compound, as it was known to occur only in the urine of living organisms. Wöhlers experiments were followed by others, in which increasingly complex organic substances were produced from inorganic ones without the involvement of any living organism. Even though vitalism has been discredited, scientific nomenclature retains the distinction between organic and inorganic compounds, still, even the broadest definition requires excluding alloys that contain carbon, including steel. The C-H definition excludes compounds that are considered organic, neither urea nor oxalic acid is organic by this definition, yet they were two key compounds in the vitalism debate. The IUPAC Blue Book on organic nomenclature specifically mentions urea and oxalic acid, other compounds lacking C-H bonds but traditionally considered organic include benzenehexol, mesoxalic acid, and carbon tetrachloride. Mellitic acid, which contains no C-H bonds, is considered an organic substance in Martian soil. The C-H bond-only rule also leads to somewhat arbitrary divisions in sets of carbon-fluorine compounds, for example, CF4 would be considered by this rule to be inorganic, whereas CF3H would be organic. Organic compounds may be classified in a variety of ways, one major distinction is between natural and synthetic compounds. Another distinction, based on the size of organic compounds, distinguishes between small molecules and polymers, natural compounds refer to those that are produced by plants or animals. Many of these are extracted from natural sources because they would be more expensive to produce artificially
14.
Transgenic
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A transgene is a gene or genetic material that has been transferred naturally, or by any of a number of genetic engineering techniques from one organism to another. The introduction of a transgene has the potential to change the phenotype of an organism, in its most precise usage, the term transgene describes a segment of DNA containing a gene sequence that has been isolated from one organism and is introduced into a different organism. This non-native segment of DNA may either retain the ability to produce RNA or protein in the organism or alter the normal function of the transgenic organisms genetic code. In general, the DNA is incorporated into the germ line. For example, in higher vertebrates this can be accomplished by injecting the foreign DNA into the nucleus of a fertilized ovum. This technique is used to introduce human disease genes or other genes of interest into strains of laboratory mice to study the function or pathology involved with that particular gene. The construction of a transgene requires the assembly of a few main parts, the transgene must contain a promoter, which is a regulatory sequence that will determine where and when the transgene is active, an exon, a protein coding sequence, and a stop sequence. These are typically combined in a plasmid and the coding sequences are typically chosen from transgenes with previously known functions. Transgenic or genetically modified organisms, be they bacteria, viruses or fungi, transgenic plants, insects, fish and mammals have been bred. Transgenic plants such as corn and soybean have replaced wild strains in agriculture in some countries, transgene escape has been documented for GMO crops since 2001 with persistence and invasiveness. Transgenetic organisms pose ethical questions and may cause biosafety problems, the idea of shaping an organism to fit a specific need isn’t a new science, selective breeding of animals and plants started before recorded history. In the 1970 and 1980s, scientists passed this hurdle by inventing procedures for combining the DNA of two different species with genetic engineering. The organisms produced by these procedures were termed transgenic, transgenesis is the same as gene therapy in the sense that they both transform cells for a specific purpose. Transgenesis will therefore change the cells, not only the somatic cells. Transgenes alter the genome by blocking the function of a host gene, they can replace the host gene with one that codes for a different protein. In 1978, yeast cells were the first organisms to undergo gene transfer, Mouse cells were first transformed in 1979, followed by mouse embryos in 1980. Most of the very first transmutations were performed by microinjection of DNA directly into cells, the first transgenic animals were only intended for genetic research to study the specific function of a gene, and by 2003, thousands of genes had been studied. A variety of plants have been designed for agriculture to produce genetically modified crops, such as corn, soybean, rapeseed oil, cotton, rice
15.
Bacillus thuringiensis
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Bacillus thuringiensis is a Gram-positive, soil-dwelling bacterium, commonly used as a biological pesticide. During sporulation, many Bt strains produce crystal proteins, called δ-endotoxins and this has led to their use as insecticides, and more recently to genetically modified crops using Bt genes, such as Bt corn. Many crystal-producing Bt strains, though, do not have insecticidal properties, B. thuringiensis was first discovered in 1901 by Japanese biologist Ishiwata Shigetane. In 1911, B. thuringiensis was rediscovered in Germany by Ernst Berliner, in 1976, Robert A. Zakharyan reported the presence of a plasmid in a strain of B. thuringiensis and suggested the plasmids involvement in endospore and crystal formation. B. thuringiensis is closely related to B. cereus, a bacterium, and B. anthracis, the cause of anthrax. Like other members of the genus, all three are aerobes capable of producing endospores, the are several dozen recognized subspecies of bacillus thuringiensis. Subspecies commonly used as insecticides include Bacillus thuringiensis subspecies kurstaki and subspecies israelensis, upon sporulation, B. thuringiensis forms crystals of proteinaceous insecticidal δ-endotoxins, which are encoded by cry genes. In most strains of B. thuringiensis, the cry genes are located on a plasmid, Cry toxins have specific activities against insect species of the orders Lepidoptera, Diptera, Coleoptera, Hymenoptera and nematodes. Thus, B. thuringiensis serves as an important reservoir of Cry toxins for production of biological insecticides, the Cry toxin is then inserted into the insect gut cell membrane, paralyzing the digestive tract and forming a pore. The insect stops eating and starves to death, live Bt bacteria may also colonize the insect which can contribute to death, the midgut bacteria of susceptible larvae may be required for B. thuringiensis insecticidal activity. In 1996 another class of proteins in Bt was discovered. Vip proteins do not share sequence homology with Cry proteins, in general do not compete for the same receptors, in 2000, a novel functional group of Cry protein, designated parasporin, was discovered from noninsecticidal B. thuringiensis isolates. The proteins of parasporin group are defined as B. thuringiensis and related bacterial parasporal proteins that are not hemolytic, as of January 2013, parasporins comprise six subfamilies. Spores and crystalline insecticidal proteins produced by B. thuringiensis have been used to control insect pests since the 1920s and are applied as liquid sprays. They are now used as specific insecticides under trade names such as DiPel, each new strain is given a unique number and registered with the U. S. The Bt tobacco was never commercialized, tobacco plants are used to test genetic modifications since they are easy to genetically and are not part of the food supply. This was the New Leaf potato, and it was removed from the market in 2001 due to lack of interest, for current crops and their acreage under cultivation, see genetically modified crops. Corn genetically modified to produce VIP was first approved in the US in 2010, in India, by 2014, more than seven million cotton farmers, occupying twenty-six million acres, had adopted Bt cotton
16.
Maize
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Maize, also known as corn, is a large grain plant first domesticated by indigenous peoples in Mexico about 10,000 years ago. The six major types of corn are dent corn, flint corn, pod corn, popcorn, flour corn, the leafy stalk of the plant produces separate pollen and ovuliferous inflorescences or ears, which are fruits, yielding kernels or seeds. Maize kernels are used in cooking as a starch. Most historians believe maize was domesticated in the Tehuacan Valley of Mexico, recent research modified this view somewhat, scholars now indicate the adjacent Balsas River Valley of south-central Mexico as the center of domestication. The Olmec and Mayans cultivated maize in numerous varieties throughout Mesoamerica, cooked and its believed that beginning about 2500 BC, the crop spread through much of the Americas. The region developed a network based on surplus and varieties of maize crops. Nevertheless, recent data indicates that the spread of maize took place even earlier, according to Piperno, A large corpus of data indicates that it was dispersed into lower Central America by 7600 BP and had moved into the inter-Andean valleys of Colombia between 7000 and 6000 BP. Since then, even earlier dates have been published, the study also demonstrated that the oldest surviving maize types are those of the Mexican highlands. Later, maize spread from this region over the Americas along two major paths and this is consistent with a model based on the archaeological record suggesting that maize diversified in the highlands of Mexico before spreading to the lowlands. Before they were domesticated, maize plants only grew small,25 millimetres long corn cobs, Maize is the most widely grown grain crop throughout the Americas, with 361 million metric tons grown in the United States in 2014. Approximately 40% of the crop—130 million tons—is used for corn ethanol, genetically modified maize made up 85% of the maize planted in the United States in 2009. After the arrival of Europeans in 1492, Spanish settlers consumed maize and explorers and traders carried it back to Europe, Spanish settlers far preferred wheat bread to maize, cassava, or potatoes. Maize flour could not be substituted for wheat for bread, since in Christian belief only wheat could undergo transubstantiation. At another level, Spaniards worried that by eating indigenous foods, which they did not consider nutritious, that not only would they weaken, despite these worries, Spaniards did consume maize and archeological evidence from Florida sites indicate they cultivated it as well. Maize spread to the rest of the world because of its ability to grow in diverse climates and it was cultivated in Spain just a few decades after Columbuss voyages and then spread to Italy, West Africa and elsewhere. The word maize derives from the Spanish form of the indigenous Taíno word for the plant and it is known by other names around the world. The word corn outside North America, Australia, and New Zealand refers to any cereal crop, in the United States, Canada, Australia, and New Zealand, corn primarily means maize, this usage started as a shortening of Indian corn. Indian corn primarily means maize, but can more specifically to multicolored flint corn used for decoration
17.
Arsenate
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The arsenate ion is AsO3−4. An arsenate is any compound that contains this ion, arsenates are salts or esters of arsenic acid. The arsenic atom in arsenate has a valency of 5 and is known as pentavalent arsenic or As. Arsenate resembles phosphate in many respects, since arsenic and phosphorus occur in the group of the periodic table. Arsenates are moderate oxidizers, with a potential of +0.56 V for reduction to arsenites. Arsenates occur naturally in a variety of minerals and those minerals may contain hydrated or anhydrous arsenates. Unlike phosphates, arsenates are not lost from a mineral during weathering, examples of arsenate-containing minerals include adamite, alarsite, annabergite, erythrite and legrandite. Arsenate can replace inorganic phosphate in the step of glycolysis that produces 1 and this yields 1-arseno-3-phosphoglycerate instead, which is unstable and quickly hydrolyzes, forming the next intermediate in the pathway, 3-phosphoglycerate. Therefore, glycolysis proceeds, but the ATP molecule that would be generated from 1, 3-bisphosphoglycerate is lost – arsenate is an uncoupler of glycolysis, explaining its toxicity. As with other compounds, arsenate can also inhibit the conversion of pyruvate into acetyl-CoA, blocking the Krebs cycle. Some species of bacteria obtain their energy by oxidizing various fuels while reducing arsenates to form arsenites, the enzymes involved are known as arsenate reductases. In 2008, bacteria were discovered that employ a version of photosynthesis with arsenites as electron donors, the researchers conjectured that historically these photosynthesizing organisms produced the arsenates that allowed the arsenate-reducing bacteria to thrive. In 2010, a team at NASAs Astrobiology Institute cultured samples of arsenic-resistant GFAJ-1 bacteria from Mono Lake, using a high in arsenate
18.
Copper
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Copper is a chemical element with symbol Cu and atomic number 29. It is a soft, malleable, and ductile metal with high thermal and electrical conductivity. A freshly exposed surface of copper has a reddish-orange color. Copper is one of the few metals that occur in nature in directly usable metallic form as opposed to needing extraction from an ore and this led to very early human use, from c.8000 BC. Copper used in buildings, usually for roofing, oxidizes to form a green verdigris, Copper is sometimes used in decorative art, both in its elemental metal form and in compounds as pigments. Copper compounds are used as agents, fungicides, and wood preservatives. Copper is essential to all living organisms as a trace dietary mineral because it is a key constituent of the enzyme complex cytochrome c oxidase. In molluscs and crustaceans, copper is a constituent of the blood pigment hemocyanin, replaced by the hemoglobin in fish. In humans, copper is found mainly in the liver, muscle, the adult body contains between 1.4 and 2.1 mg of copper per kilogram of body weight. The filled d-shells in these elements contribute little to interatomic interactions, unlike metals with incomplete d-shells, metallic bonds in copper are lacking a covalent character and are relatively weak. This observation explains the low hardness and high ductility of single crystals of copper, at the macroscopic scale, introduction of extended defects to the crystal lattice, such as grain boundaries, hinders flow of the material under applied stress, thereby increasing its hardness. For this reason, copper is supplied in a fine-grained polycrystalline form. The softness of copper partly explains its high conductivity and high thermal conductivity. The maximum permissible current density of copper in open air is approximately 3. 1×106 A/m2 of cross-sectional area, Copper is one of a few metallic elements with a natural color other than gray or silver. Pure copper is orange-red and acquires a reddish tarnish when exposed to air, as with other metals, if copper is put in contact with another metal, galvanic corrosion will occur. A green layer of verdigris can often be seen on old structures, such as the roofing of many older buildings. Copper tarnishes when exposed to sulfur compounds, with which it reacts to form various copper sulfides. There are 29 isotopes of copper, 63Cu and 65Cu are stable, with 63Cu comprising approximately 69% of naturally occurring copper, both have a spin of 3⁄2
19.
Fluorine
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Fluorine is a chemical element with symbol F and atomic number 9. It is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions, as the most electronegative element, it is extremely reactive, almost all other elements, including some noble gases, form compounds with fluorine. Among the elements, fluorine ranks 24th in universal abundance and 13th in terrestrial abundance, proposed as an element in 1810, fluorine proved difficult and dangerous to separate from its compounds, and several early experimenters died or sustained injuries from their attempts. Only in 1886 did French chemist Henri Moissan isolate elemental fluorine using low-temperature electrolysis, industrial production of fluorine gas for uranium enrichment, its largest application, began during the Manhattan Project in World War II. Owing to the expense of refining pure fluorine, most commercial applications use fluorine compounds, the rest of the fluorite is converted into corrosive hydrogen fluoride en route to various organic fluorides, or into cryolite which plays a key role in aluminium refining. Organic fluorides have very high chemical and thermal stability, their uses are as refrigerants, electrical insulation and cookware. Pharmaceuticals such as atorvastatin and fluoxetine also contain fluorine, and the fluoride ion inhibits dental cavities, global fluorochemical sales amount to more than US$15 billion a year. Fluorocarbon gases are generally greenhouse gases with global-warming potentials 100 to 20,000 times that of carbon dioxide, organofluorine compounds persist in the environment due to the strength of the carbon–fluorine bond. Fluorine has no metabolic role in mammals, a few plants synthesize organofluorine poisons that deter herbivores. Fluorine atoms have nine electrons, one fewer than neon, and electron configuration 1s22s22p5, the outer electrons are ineffective at nuclear shielding, and experience a high effective nuclear charge of 9 −2 =7, this affects the atoms physical properties. Fluorines first ionization energy is third-highest among all elements, behind helium and neon and it also has a high electron affinity, second only to chlorine, and tends to capture an electron to become isoelectronic with the noble gas neon, it has the highest electronegativity of any element. Fluorine atoms have a small covalent radius of around 60 picometers, similar to those of its period neighbors oxygen, conversely, bonds to other atoms are very strong because of fluorines high electronegativity. Unreactive substances like powdered steel, glass fragments, and asbestos fibers react quickly with cold fluorine gas, wood, reactions of elemental fluorine with metals require varying conditions. Some solid nonmetals react vigorously in liquid air temperature fluorine, hydrogen sulfide and sulfur dioxide combine readily with fluorine, the latter sometimes explosively, sulfuric acid exhibits much less activity, requiring elevated temperatures. Hydrogen, like some of the metals, reacts explosively with fluorine. Carbon, as black, reacts at room temperature to yield fluoromethane. Graphite combines with fluorine above 400 °C to produce non-stoichiometric carbon monofluoride, higher temperatures generate gaseous fluorocarbons, heavier halogens react readily with fluorine as does the noble gas radon, of the other noble gases, only xenon and krypton react, and only under special conditions. At room temperature, fluorine is a gas of diatomic molecules and it has a characteristic pungent odor detectable at 20 ppb
20.
Sulfur
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Sulfur or sulphur is a chemical element with symbol S and atomic number 16. It is abundant, multivalent, and nonmetallic, under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a yellow crystalline solid at room temperature. Chemically, sulfur reacts with all elements except for gold, platinum, iridium, tellurium, though sometimes found in pure, native form, sulfur usually occurs as sulfide and sulfate minerals. Being abundant in native form, sulfur was known in ancient times, being mentioned for its uses in ancient India, ancient Greece, China, in the Bible, sulfur is called brimstone. Today, almost all elemental sulfur is produced as a byproduct of removing sulfur-containing contaminants from natural gas, the greatest commercial use of the element is the production of sulfuric acid for sulfate and phosphate fertilizers, and other chemical processes. The element sulfur is used in matches, insecticides, and fungicides, many sulfur compounds are odoriferous, and the smells of odorized natural gas, skunk scent, grapefruit, and garlic are due to organosulfur compounds. Hydrogen sulfide gives the characteristic odor to rotting eggs and other biological processes, sulfur is an essential element for all life, but almost always in the form of organosulfur compounds or metal sulfides. Three amino acids and two vitamins are organosulfur compounds, many cofactors also contain sulfur including glutathione and thioredoxin and iron–sulfur proteins. Disulfides, S–S bonds, confer mechanical strength and insolubility of the keratin, found in outer skin, hair. Sulfur is one of the chemical elements needed for biochemical functioning and is an elemental macronutrient for all organisms. Sulfur is derived from the Latin word sulpur, which was Hellenized to sulphur, the spelling sulfur appears toward the end of the Classical period. In 12th-century Anglo-French, it was sulfre, in the 14th century the Latin ph was restored, for sulphre, the parallel f~ph spellings continued in Britain until the 19th century, when the word was standardized as sulphur. Sulfur was the form chosen in the United States, whereas Canada uses both, the IUPAC adopted the spelling sulfur in 1990, as did the Nomenclature Committee of the Royal Society of Chemistry in 1992, restoring the spelling sulfur to Britain. Sulfur forms polyatomic molecules with different chemical formulas, the best-known allotrope being octasulfur, cyclo-S8. The point group of cyclo-S8 is D4d and its dipole moment is 0 D. Octasulfur is a soft, bright-yellow solid that is odorless and it melts at 115.21 °C, boils at 444.6 °C and sublimes easily. At 95.2 °C, below its melting temperature, cyclo-octasulfur changes from α-octasulfur to the β-polymorph, the structure of the S8 ring is virtually unchanged by this phase change, which affects the intermolecular interactions. At higher temperatures, the viscosity decreases as depolymerization occurs, molten sulfur assumes a dark red color above 200 °C
21.
Pesticide application
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Pesticide application refers to the practical way in which pesticides, are delivered to their biological targets. Public concern about the use of pesticides has highlighted the need to make this process as efficient as possible, in order to minimise their release into the environment, seed treatments can achieve exceptionally high efficiencies, in terms of effective dose-transfer to a crop. One of the most common forms of application, especially in conventional agriculture, is the use of mechanical sprayers. Hydraulic sprayers consists of a tank, a pump, a lance or boom, sprayers convert a pesticide formulation, often containing a mixture of water and chemical, into droplets, which can be large rain-type drops or tiny almost-invisible particles. This conversion is accomplished by forcing the mixture through a spray nozzle under pressure. The size of droplets can be altered through the use of different nozzle sizes, or by altering the pressure under which it is forced, large droplets have the advantage of being less susceptible to spray drift, but require more water per unit of land covered. Due to static electricity, small droplets are able to contact with a target organism. Traditional agricultural crop pesticides can either be applied pre-emergent or post-emergent, an example of pre-emergent pesticide application is atrazine application for corn. Similarly, glyphosate mixtures are often applied pre-emergent on agricultural fields to remove early-germinating weeds, pre-emergent application equipment often has large, wide tires designed to float on soft soil, minimizing both soil compaction and damage to planted crops. Post-emergent pesticide application requires the use of specific chemicals chosen minimize harm to the target organism. An example is 2, 4-Dichlorophenoxyacetic acid, which will injure broadleaf weeds, such a chemical has been used extensively on wheat crops, for example. A number of companies have also created genetically modified organisms that are resistant to various pesticides, examples include glyphosate-resistant soybeans and Bt maize, which change the types of formulations involved in addressing post-emergent pesticide pressure. As plants have already germinated, post-emergent pesticide application necessitates limited field contact in order to minimize losses due to crop, typical industrial application equipment will utilize very tall and narrow tires and combine this with a sprayer body which can be raised and lowered depending on crop height. These sprayers usually carry the label ‘high-clearance’ as they can rise over growing crops, in addition, these sprayers often have very wide booms in order to minimize the number of passes required over a field, again designed to limit crop damage and maximize efficiency. In industrial agriculture, spray booms 120 feet wide are not uncommon, especially in agriculture with large. Related to this, aerial pesticide application is a method of top dressing a pesticide to a crop which eliminates physical contact with soil. Air Blast sprayers, also known as air-assisted or mist sprayers, are used for tall crops, such as tree fruit. These can be used for insects, weeds, and other pests to crops, humans, air blast sprayers inject liquid into a fast-moving stream of air, breaking down large droplets into smaller particles by introducing a small amount of liquid into a fast-moving stream of air
22.
Aerosol
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An aerosol is a colloid of fine solid particles or liquid droplets, in air or another gas. Aerosols can be natural or artificial, examples of natural aerosols are fog, forest exudates and geyser steam. Examples of artificial aerosols are haze, dust, particulate air pollutants, the liquid or solid particles have diameter mostly smaller than 1 μm or so, larger particles with a significant settling speed make the mixture a suspension, but the distinction is not clear-cut. In general conversation, aerosol refers to an aerosol spray that delivers a consumer product from a can or similar container. Other technological applications of aerosols include dispersal of pesticides, medical treatment of respiratory illnesses, diseases can also spread by means of small droplets in the breath, also called aerosols. Aerosol science covers generation and removal of aerosols, technological application of aerosols, effects of aerosols on the environment and people, an aerosol is defined as a colloidal system of solid or liquid particles in a gas. An aerosol includes both the particles and the gas, which is usually air. Frederick G. Donnan presumably first used the term aerosol during World War I to describe an aero-solution and this term developed analogously to the term hydrosol, a colloid system with water as the dispersing medium. Primary aerosols contain particles introduced directly into the gas, secondary aerosols form through gas-to-particle conversion, various types of aerosol, classified according to physical form and how they were generated, include dust, fume, mist, smoke and fog. There are several measures of aerosol concentration, Environmental science and health often uses the mass concentration, defined as the mass of particulate matter per unit volume with units such as μg/m3. Also commonly used is the concentration, the number of particles per unit volume with units such as number/m3 or number/cm3. The size of particles has an influence on their properties. A monodisperse aerosol, producible in the laboratory, contains particles of uniform size, most aerosols, however, as polydisperse colloidal systems, exhibit a range of particle sizes. Liquid droplets are almost always nearly spherical, but scientists use an equivalent diameter to characterize the properities of various shapes of solid particles, the equivalent diameter is the diameter of a spherical particle with the same value of some physical property as the irregular particle. The equivalent volume diameter is defined as the diameter of a sphere of the volume as that of the irregular particle. Also commonly used is the aerodynamic diameter, for a monodisperse aerosol, a single number—the particle diameter—suffices to describe the size of the particles. However, more complicated particle-size distributions describe the sizes of the particles in a polydisperse aerosol and this distribution defines the relative amounts of particles, sorted according to size. One approach to defining the size distribution uses a list of the sizes of every particle in a sample
23.
Biopesticide
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Biopesticides, a contraction of biological pesticides, include several types of pest management intervention, through predatory, parasitic, or chemical relationships. The term has been associated historically with biological control - and by implication - the manipulation of living organisms, regulatory positions can be influenced by public perceptions, thus, in the EU, biopesticides have been defined as a form of pesticide based on micro-organisms or natural products. They are obtained from organisms including plants, bacteria and other microbes, fungi, nematodes and they are often important components of integrated pest management programmes, and have received much practical attention as substitutes to synthetic chemical plant protection products. Biopesticides can be classified into classes, Microbial pesticides which consist of bacteria. Entomopathogenic nematodes are often classed as microbial pesticides, even though they are multi-cellular. Four groups are in use, pyrethrum, rotenone, neem oil. Plant-incorporated protectants have genetic material from other species incorporated into their genetic material and their use is controversial, especially in many European countries. RNAi pesticides, some of which are topical and some of which are absorbed by the crop, Biopesticides have usually no known function in photosynthesis, growth or other basic aspects of plant physiology. Instead, they are active against biological pests, many chemical compounds have been identified that are produced by plants to protect them from pests. These materials are biodegradable and renewable alternatives, which can be economical for practical use, organic farming systems embraces this approach to pest control. RNA interference is under study for use as a spray-on insecticide by multiple companies, including Monsanto, Syngenta. Such sprays do not modify the genome of the target plant, the RNA could be modified to maintain its effectiveness as target species evolve tolerance to the original. RNA is a relatively fragile molecule that generally degrades within days or weeks of application, Monsanto estimated costs to be on the order of $5/acre. RNAi has been used to target weeds that tolerate Monsantos Roundup herbicide and this strategy would allow the continued use of glyphosate-based herbicides, but would not per se assist a herbicide rotation strategy that relied on alternating Roundup with others. They can be made with precision to kill some insect species. Monsanto is also developing an RNA spray to kill potato beetles One challenge is to make it linger on the plant for a week, the Potato beetle has become resistant to more than 60 conventional insecticides. Monsanto lobbied the U. S. EPA to exempt RNAi pesticide products from any specific regulations and be exempted from rodent toxicity, allergenicity, in 2014 an EPA advisory group found little evidence of a risk to people from eating RNA. However, in 2012, the Australian Safe Food Foundation alleged that the RNA trigger designed to change wheats starch content might interfere with the gene for a liver enzyme
24.
Rosin
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It is semi-transparent and varies in color from yellow to black. At room temperature rosin is brittle, but it melts at stove-top temperature and it chiefly consists of various resin acids, especially abietic acid. The term colophony comes from colophonia resina, Latin for resin from Colophon, Rosin is an ingredient in printing inks, photocopying and laser printing paper, varnishes, adhesives, soap, paper sizing, soda, soldering fluxes, and sealing wax. Rosin can be used as an agent in medicines and chewing gum. It is denoted by E number E915, a related glycerol ester can be used as an emulsifier in soft drinks. In pharmaceuticals, rosin forms an ingredient in several plasters and ointments, in industry, rosin is a flux used in soldering. It is frequently seen as the burnt or clear residue around new soldering, a mixture of pitch and rosin is used to make a surface against which glass is polished when making optical components such as lenses. Rosin is added in quantities to traditional linseed oil/sand gap fillers. When mixed with waxes and oils, rosin is the ingredient of mystic smoke, a gum which. Extra substances such as beeswax, gold, silver, tin, or meteoric iron are added to the rosin to modify its stiction/friction properties. Powdered rosin can be applied to new hair, for example with a pad or cloth. Rosin is often applied to the bow before playing the instrument, lighter rosin is generally preferred for violins and violas, and in high-humidity climates, while darker rosins are preferred for cellos, and for players in cool, dry areas. There are also specific, distinguishing types for basses—for more see Bow, violin rosin can be applied to the bridges in other musical instruments, such as the banjo and banjolele, in order to prevent the bridge from moving during vigorous playing. Ballet, flamenco, and Irish dancers are known to rub the tips and it was at one time used in the same way in fencing and is still used as such by boxers. Gymnasts and team handball players use it to improve grip, rock climbers have used it in some locations, but it fouls the rock, so usage is now highly discouraged. Olympic weightlifters rub the soles of their boots in rosin to improve traction on the platform. It is applied onto the line of drag racing courses used to improve traction. Bull riders rub rosin on their rope and glove for additional grip, baseball pitchers and ten-pin bowlers may use a small cloth bag of powdered rosin for better ball control
25.
Pinophyta
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The Pinophyta, also known as Coniferophyta or Coniferae, or commonly as conifers, are a division of vascular land plants containing a single class, Pinopsida. They are gymnosperms, cone-bearing seed plants, all extant conifers are perennial woody plants with secondary growth. The great majority are trees, though a few are shrubs, examples include cedars, Douglas firs, cypresses, firs, junipers, kauri, larches, pines, hemlocks, redwoods, spruces, and yews. As of 1998, the division Pinophyta was estimated to contain eight families,68 genera, although the total number of species is relatively small, conifers are ecologically important. They are the dominant plants over large areas of land, most notably the taiga of the Northern Hemisphere, boreal conifers have many wintertime adaptations. The narrow conical shape of northern conifers, and their downward-drooping limbs, many of them seasonally alter their biochemistry to make them more resistant to freezing. While tropical rainforests have more biodiversity and turnover, the conifer forests of the world represent the largest terrestrial carbon sink. Conifers are of economic value for softwood lumber and paper production. The earliest conifers in the record date to the late Carboniferous period, possibly arising from Cordaites. Pinophytes, Cycadophytes, and Ginkgophytes all developed at this time, an important adaptation of these gymnosperms was allowing plants to live without being so dependent on water. Other adaptations are pollen and the seed, which allows the embryo to be transported and developed elsewhere, Conifers appear to be one of the taxa that benefited from the Permian–Triassic extinction event, and were the dominant land plants of the Mesozoic. They were overtaken by the plants, which first appeared in the Cretaceous. They were the food of herbivorous dinosaurs, and their resins and poisons would have given protection against herbivores. Reproductive features of modern conifers had evolved by the end of the Mesozoic era, Conifer is a Latin word, a compound of conus and ferre, meaning the one that bears cone. A descriptive name in use for the conifers is Coniferae. Alternatively, descriptive botanical names may also be used at any rank above family and this means that if conifers are considered a division, they may be called Pinophyta or Coniferae. As a class they may be called Pinopsida or Coniferae, as an order they may be called Pinales or Coniferae or Coniferales. Conifers are the largest and economically most important component group of the gymnosperms, the division Pinophyta consists of just one class, Pinopsida, which includes both living and fossil taxa
26.
Oil of wintergreen
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Methyl salicylate is an organic ester naturally produced by many species of plants, particularly wintergreens. It is also produced, used as a fragrance, in foods and beverages. The compound methyl salicylate was first isolated in 1843 by the French chemist Auguste André Thomas Cahours and this compound is probably produced as an anti-herbivore defense. If the plant is infected with insects, the release of methyl salicylate may function as an aid in the recruitment of beneficial insects to kill the herbivorous insects. Aside from its toxicity, methyl salicylate may also be used by plants as a pheromone to warn other plants of such as tobacco mosaic virus. Numerous plants produce methyl salicylate in very small amounts, lenta, the black birch, all species of the genus Spiraea in the family Rosaceae, also called the meadowsweets, species of the genus Polygala in the family Polygalaceae. Methyl salicylate can be produced by esterifying salicylic acid with methanol, however, in the body it metabolizes into salicylates, including salicylic acid, a known NSAID. in low concentrations as a flavoring agent in chewing gum and mints. When mixed with sugar and dried it is a potentially entertaining source of triboluminescence and this effect can be observed by crushing wintergreen Life Savers in a dark room. Providing fragrance to various products and as an agent for some organophosphate pesticides. This clearing generally only takes a few minutes, but the tissue must first be dehydrated in alcohol, as a transfer agent, to produce a manual copy of an image on a surface. In small amounts, to lower the point of glacial acetic acid for transport. A simulant or surrogate for the research of chemical warfare agent sulfur mustard, an antiseptic in Listerine mouthwash produced by the Johnson & Johnson company. Restoring the elastomeric properties of old rubber rollers, especially in printers, in pure form, methyl salicylate is harmful, when taken orally. A single teaspoon of methyl salicylate contains approximately 6 g of salicylate, the lowest published lethal dose is 101 mg/kg body weight in adult humans. It has proven fatal to children in doses as small as 4 ml. Most instances of human toxicity due to methyl salicylate are a result of over-application of topical analgesics, some people have intentionally ingested large amounts of oil of wintergreen. Salicylate, the metabolite of methyl salicylate, may be quantitated in blood
27.
Neem oil
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Neem oil is a vegetable oil pressed from the fruits and seeds of the neem, an evergreen tree which is endemic to the Indian subcontinent and has been introduced to many other areas in the tropics. It is the most important of the available products of neem for organic farming. Neem oil varies in color, it can be yellow, yellowish brown, reddish brown, dark brown, greenish brown. It has a strong odor that is said to combine the odours of peanut. It is composed mainly of triglycerides and contains many triterpenoid compounds and it is hydrophobic in nature, in order to emulsify it in water for application purposes, it is formulated with surfactants. Azadirachtin is the most well known and studied triterpenoid in neem oil, the azadirachtin content of neem oil varies from 300ppm to over 2500ppm depending on the extraction technology and quality of the neem seeds crushed. Nimbin is another triterpenoid which has been credited with some of neem oils properties as an antiseptic, antifungal, antipyretic, Neem oil also contains several sterols, including. The neem oil yield that can be obtained from neem seed kernels also varies widely in literature from 25% to 45%, the oil can be obtained through pressing of the seed kernel both through cold pressing or through a process incorporating temperature controls 40 to 50 °C. Neem seed oil can also be obtained by solvent extraction of the seed, fruit, oil. A large industry in India extracts the oil remaining in the cake using hexane. This solvent-extracted oil is of a quality as compared to the cold pressed oil and is mostly used for soap manufacturing. Neem cake is a by-product obtained in the solvent extraction process for neem oil, Neem oil is not used for cooking purposes. In India, it is used for preparing cosmetics and in Ayurvedic, Unani and folklore traditional medicine, the most frequently reported indications in ancient Ayurvedic writings are skin diseases, inflammations and fevers, and more recently rheumatic disorders. Traditional Ayurvedic uses of neem include the treatment of acne, fever, leprosy, malaria, ophthalmia, various folk remedies for neem include use as an anthelmintic, antifeedant, antiseptic, diuretic, emmenagogue, contraceptive, febrifuge, parasiticide, pediculocide and insecticide. It has been used in medicine for the treatment of tetanus, urticaria, eczema, scrofula. Traditional routes of administration of neem extracts included oral, vaginal and topical use, Neem oil has an extensive history of human use in India and surrounding regions for a variety of therapeutic purposes. Puri has given an account of traditional uses and therapeutic indications and pharmacological studies of this oil, Neem seed oil has also been found to prevent implantation and may even have an abortifacient effect similar to pennyroyal, juniper berries, wild ginger, myrrh and angelica. The effects were seen as many as ten days after fertilization in rats though it was most effective at no more than three days, in a study on rats, neem oil was given orally eight to ten days after implantation of the fetus on the uterine wall
28.
Essential oil
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Not to be confused with Essential fatty acid An essential oil is a concentrated hydrophobic liquid containing volatile aroma compounds from plants. Essential oils are known as volatile oils, ethereal oils, aetherolea, or simply as the oil of the plant from which they were extracted. An oil is essential in the sense that it contains the essence of the plants fragrance—the characteristic fragrance of the plant from which it is derived, Essential oils are generally extracted by distillation, often by using steam. Other processes include expression, solvent extraction, absolute oil extraction, resin tapping and they are used in perfumes, cosmetics, soaps and other products, for flavoring food and drink, and for adding scents to incense and household cleaning products. Essential oils have been used throughout history. The earliest recorded mention of the techniques and methods used to produce essential oils is believed to be that of Ibn al-Baitar, rather than refer to essential oils themselves, modern works typically discuss specific chemical compounds of which the essential oils are composed. For example, methyl salicylate rather than oil of wintergreen, interest in essential oils has revived in recent decades with the popularity of aromatherapy, a branch of alternative medicine that uses essential oils and other aromatic compounds. Oils are volatilized, diluted in an oil and used in massage, diffused in the air by a nebulizer, heated over a candle flame. Claims for the efficacy of treatments, and treatment of cancers in particular, are now subject to regulation in most countries. Most common essential oils such as lavender, peppermint, tea oil, patchouli. Raw plant material, consisting of the flowers, leaves, wood, bark, roots, seeds, as the water is heated, the steam passes through the plant material, vaporizing the volatile compounds. The vapors flow through a coil, where they condense back to liquid, most oils are distilled in a single process. One exception is ylang-ylang which is purifed through a fractional distillation, the recondensed water is referred to as a hydrosol, hydrolat, herbal distillate, or plant water essence, which may be sold as another fragrant product. Popular hydrosols include rose water, lavender water, lemon balm, clary sage, the use of herbal distillates in cosmetics is increasing. Some plant hydrosols have unpleasant smells and are not sold. Most citrus peel oils are expressed mechanically or cold-pressed, due to the relatively large quantities of oil in citrus peel and low cost to grow and harvest the raw materials, citrus-fruit oils are cheaper than most other essential oils. Lemon or sweet orange oils are obtained as byproducts of the citrus industry, before the discovery of distillation, all essential oils were extracted by pressing. Most flowers contain too little oil to undergo expression, but their chemical components are too delicate
29.
Genetically engineered potato
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A genetically engineered potato is a potato that has had its genes modified, using genetic engineering. Goals of modification include introducing pest resistance, tweaking the amounts of chemicals produced by the plant. Varieties modified to produce amounts of starches may be approved for industrial use only. The genetically modified Innate potato was approved by the USDA in 2014, the cultivar was developed by J. R. Simplot Company. It is designed to resist blackspot bruising, browning and to less of the amino acid asparagine that turns into acrylamide during the frying of potatoes. Acrylamide is a human carcinogen, so reduced levels of it in fried potato foods is desirable. The Innate name comes from the fact that this variety does not contain any material from other species and uses RNA interference to switch off genes. Simplot hopes that not including genes from other species will assuage consumer fears about biotechnology, the Innate potato is not a single cultivar, rather, it is a group of potato varieties that have had the same genetic alterations applied using the same process. Five different potato varieties have been transformed, creating versions of the varieties, with all of the original traits. Ranger Russet, Russet Burbank, and Atlantic potatoes have all been transformed by Simplot, modifications of each variety involved two transformations, one for each of the two new traits, thus there was a total of ten transformation events in developing the different Innate varieties. McDonalds is a consumer of potatoes in the US. The Food and Water Watch has petitioned the company to reject the newly marketed Innate potatoes, mcDonalds has announced that they have ruled out using Innate. In 1995, Monsanto introduced the NewLeaf variety of potato which was their first genetically modified crop and it was designed to resist attack from the Colorado potato beetle due to the insertion of Bt toxin producing genes from the bacterium Bacillus thuringiensis. The insect-resistant potatoes found only a market, and Monsanto discontinued the sale of seed in 2001. Amflora was a developed by BASF Plant Science for production of pure amylopectin starch for processing into waxy potato starch. A modified Désirée potato was developed in the 1990s by biochemist John Gatehouse at Cambridge Agricultural Genetics and had gone two years of field trials at Rothamsted Experimental Station. The potatoes were modified to express the Galanthus nivalis agglutinin gene from the Galanthus plant and this variety of potatoes is the one which was involved in the Pusztai affair. They developed this potato for blight resistance by inserting a gene and this gene, which conferred the resistance to blight, was isolated from a wild relative of potatoes, Solanum venturii, which is a native of South America
30.
Protein
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Proteins are large biomolecules, or macromolecules, consisting of one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, a linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide, short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called peptides, or sometimes oligopeptides. The individual amino acid residues are bonded together by peptide bonds, the sequence of amino acid residues in a protein is defined by the sequence of a gene, which is encoded in the genetic code. In general, the code specifies 20 standard amino acids, however. Sometimes proteins have non-peptide groups attached, which can be called prosthetic groups or cofactors, proteins can also work together to achieve a particular function, and they often associate to form stable protein complexes. Once formed, proteins only exist for a period of time and are then degraded and recycled by the cells machinery through the process of protein turnover. A proteins lifespan is measured in terms of its half-life and covers a wide range and they can exist for minutes or years with an average lifespan of 1–2 days in mammalian cells. Abnormal and or misfolded proteins are degraded more rapidly due to being targeted for destruction or due to being unstable. Like other biological macromolecules such as polysaccharides and nucleic acids, proteins are essential parts of organisms, many proteins are enzymes that catalyse biochemical reactions and are vital to metabolism. Proteins also have structural or mechanical functions, such as actin and myosin in muscle and the proteins in the cytoskeleton, other proteins are important in cell signaling, immune responses, cell adhesion, and the cell cycle. In animals, proteins are needed in the diet to provide the essential amino acids that cannot be synthesized, digestion breaks the proteins down for use in the metabolism. Methods commonly used to study structure and function include immunohistochemistry, site-directed mutagenesis, X-ray crystallography, nuclear magnetic resonance. Most proteins consist of linear polymers built from series of up to 20 different L-α-amino acids, all proteinogenic amino acids possess common structural features, including an α-carbon to which an amino group, a carboxyl group, and a variable side chain are bonded. Only proline differs from this structure as it contains an unusual ring to the N-end amine group. The amino acids in a chain are linked by peptide bonds. Once linked in the chain, an individual amino acid is called a residue, and the linked series of carbon, nitrogen. The peptide bond has two forms that contribute some double-bond character and inhibit rotation around its axis, so that the alpha carbons are roughly coplanar
31.
Colorado potato beetle
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The Colorado potato beetle, also known as the Colorado beetle, the ten-striped spearman, the ten-lined potato beetle or the potato bug, is a major pest of potato crops. It is approximately 10 millimetres long, with a bright yellow/orange body, the Colorado potato beetle was first discovered by Thomas Nuttal in 1811 and described in 1824 by Thomas Say from specimens collected in the Rocky Mountains on Solanum rostratum. Adult beetles average 6-11 mm in length and 3 mm in width, the beetles are orange-yellow in colour with ten characteristic black stripes on the elytra. The species name decemlineata, meaning ten lines derives from this feature, adult beetles may, however, be visually confused with L. juncta, the false potato beetle, which is not an agricultural pest. L. juncta also has alternating black and white strips on its back, the orange-pink larvae have a large, nine segment, abdomen and black head, prominent spiracles and may measure up to 15 mm in length in their final instar stage. The beetle larva has four instar stages, the head remains black throughout these stages, but the pronotum changes colour from black in first- and second-instar larvae to having an orange-brown edge in its third-instar. In fourth-instar larvae, about half the pronotum is coloured light brown, the beetle is native to America and Mexico and is present in all States of American except Alaska, California, Hawaii, and Nevada. It now has a distribution across Europe and Asia. Its first association with the plant, Solanum tuberosum, was not known until about 1859 when it began destroying potato crops in the region of Omaha. It had spread east and reached the Atlantic Coast by 1874, in 1877, the Colorado beetle reached the United Kingdom and was first recorded from Liverpool docks. There have been many further outbreaks but the species has been eradicated in the UK at least 163 times, the last major outbreak was in 1976. It remains as a quarantine pest in the United Kingdom and is monitored by DEFRA in order to prevent it becoming established. The population increased dramatically during and immediately following World War II and spread eastward, after World War II, in the Soviet occupation zone of Germany, almost half of all potato fields were infested by the beetle by 1950. The GDR government made the claim that the beetles were dropped by American planes, in East Germany they were known as Amikäfer. In the EU it remains a regulated pest for the UK, Republic of Ireland, Balearic Islands, Cyprus, Malta and southern parts of Sweden and Finland. It is not established in any of these Member States, Colorado potato beetle females are very prolific, they can lay as many as 800 eggs. The eggs are yellow to orange, and are about 1 mm long and they are usually deposited in batches of about 30 on the underside of host leaves. Development of all life depends on temperature
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RNA
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Ribonucleic acid is a polymeric molecule essential in various biological roles in coding, decoding, regulation, and expression of genes. RNA and DNA are nucleic acids, and, along with proteins and carbohydrates, like DNA, RNA is assembled as a chain of nucleotides, but unlike DNA it is more often found in nature as a single-strand folded onto itself, rather than a paired double-strand. Cellular organisms use messenger RNA to convey information that directs synthesis of specific proteins. Many viruses encode their genetic information using an RNA genome, some RNA molecules play an active role within cells by catalyzing biological reactions, controlling gene expression, or sensing and communicating responses to cellular signals. One of these processes is protein synthesis, a universal function where RNA molecules direct the assembly of proteins on ribosomes. This process uses transfer RNA molecules to deliver amino acids to the ribosome, analysis of these RNAs has revealed that they are highly structured. Unlike DNA, their structures do not consist of long double helices, in this fashion, RNAs can achieve chemical catalysis. For instance, determination of the structure of the enzyme that catalyzes peptide bond formation—revealed that its active site is composed entirely of RNA. Each nucleotide in RNA contains a sugar, with carbons numbered 1 through 5. A base is attached to the 1 position, in general, adenine, cytosine, guanine, adenine and guanine are purines, cytosine and uracil are pyrimidines. A phosphate group is attached to the 3 position of one ribose, the phosphate groups have a negative charge each, making RNA a charged molecule. The bases form hydrogen bonds between cytosine and guanine, between adenine and uracil and between guanine and uracil, however, other interactions are possible, such as a group of adenine bases binding to each other in a bulge, or the GNRA tetraloop that has a guanine–adenine base-pair. An important structural feature of RNA that distinguishes it from DNA is the presence of a group at the 2 position of the ribose sugar. The A-form geometry results in a deep and narrow major groove. RNA is transcribed with only four bases, but these bases, pseudouridine, in which the linkage between uracil and ribose is changed from a C–N bond to a C–C bond, and ribothymidine are found in various places. Another notable modified base is hypoxanthine, a deaminated adenine base whose nucleoside is called inosine, inosine plays a key role in the wobble hypothesis of the genetic code. The specific roles of many of these modifications in RNA are not fully understood, the functional form of single-stranded RNA molecules, just like proteins, frequently requires a specific tertiary structure. The scaffold for this structure is provided by secondary structural elements that are hydrogen bonds within the molecule and this leads to several recognizable domains of secondary structure like hairpin loops, bulges, and internal loops
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RNA interference
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RNA interference is a biological process in which RNA molecules inhibit gene expression or translation, by neutralizing targeted mRNA molecules. Historically, it was known by names, including co-suppression, post-transcriptional gene silencing. Only after these apparently unrelated processes were fully understood did it become clear that all described the RNAi phenomenon. Mello shared the 2006 Nobel Prize in Physiology or Medicine for their work on RNA interference in the nematode worm Caenorhabditis elegans, since the discovery of RNAi and its regulatory potentials, it has become evident that RNAi has immense potential in suppression of desired genes. RNAi is now known as precise, efficient, stable and better than antisense technology for gene suppression, two types of small ribonucleic acid molecules – microRNA and small interfering RNA – are central to RNA interference. RNA interference has an important role in defending cells against parasitic nucleotide sequences – viruses, each siRNA is unwound into two single-stranded RNAs, the passenger strand and the guide strand. The passenger strand is degraded and the strand is incorporated into the RNA-induced silencing complex. In some organisms, this process spreads systemically, despite the initially limited molar concentrations of siRNA, the pathway is also used as a practical tool in biotechnology, medicine and insecticides. When the dsRNA is exogenous, the RNA is imported directly into the cytoplasm, the initiating dsRNA can also be endogenous, as in pre-microRNAs expressed from RNA-coding genes in the genome. The primary transcripts from such genes are first processed to form the characteristic structure of pre-miRNA in the nucleus. Thus, the two pathways, exogenous and endogenous, converge at the RISC. Bioinformatics studies on the genomes of multiple organisms suggest this length maximizes target-gene specificity and these short double-stranded fragments are called small interfering RNAs. These siRNAs are then separated into single strands and integrated into an active RISC, RLC includes Dicer-2 and R2D2, and is crucial to unite Ago2 and RISC. TATA-binding protein-associated factor 11 assembles the RLC by facilitating Dcr-2-R2D2 tetramerization, association with TAF11 would convert the R2-D2-Initiator complex into the RLC. R2D2 carries tandem double-stranded RNA-binding domains to recognize the thermodynamically stable terminus of siRNA duplexes, loading is asymmetric, the MID domain of Ago2 recognizes the thermodynamically stable end of the siRNA. Therefore, the passenger strand whose 5′ end is discarded by MID is ejected, after integration into the RISC, siRNAs base-pair to their target mRNA and cleave it, thereby preventing it from being used as a translation template. Differently from siRNA, a miRNA-loaded RISC complex scans cytoplasmic mRNAs for potential complementarity, exogenous dsRNA is detected and bound by an effector protein, known as RDE-4 in C. elegans and R2D2 in Drosophila, that stimulates dicer activity. This protein only binds long dsRNAs, but the mechanism producing this length specificity is unknown and this RNA-binding protein then facilitates the transfer of cleaved siRNAs to the RISC complex
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Gene silencing
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Gene silencing is a general term used to describe the regulation of gene expression. In particular, this refers to the ability of a cell to prevent the expression of a certain gene. Gene silencing can occur during either transcription or translation and is used in research. In particular, methods used to silence genes are being used to produce therapeutics to combat cancer and diseases, such as infectious diseases. Gene silencing is often considered the same as gene knockout, when genes are silenced, their expression is reduced. In contrast, when genes are knocked out, they are erased from the organisms genome and. In addition, they provide a complete view on the development of diseases since diseases are generally associated with genes that have a reduced expression. Oligonucleotides, which are nucleic acid fragments, bind to complementary target mRNA molecules when added to the cell. These molecules can be composed of single-stranded DNA or RNA and are generally 13–25 nucleotides long, the antisense oligonucleotides can affect gene expression in two ways, by using an RNase H-dependent mechanism or by using a steric blocking mechanism. RNase H-dependent oligonucleotides cause the target molecules to be degraded. The majority of drugs function through the RNase H-dependent mechanism. This mechanism is thought to be efficient, resulting in an approximately 80% to 95% decrease in the protein. Ribozymes are catalytic RNA molecules used to inhibit gene expression and these molecules work by cleaving mRNA molecules, essentially silencing the genes that produced them. Sidney Altman and Thomas Cech first discovered catalytic RNA molecules, RNase P and group II intron ribozymes, in 1989, several types of ribozyme motifs exist, including hammerhead, hairpin, hepatitis delta virus, group I, group II, and RNase P ribozymes. Hammerhead, hairpin, and hepatitis delta virus ribozyme motifs are found in viruses or viroid RNAs. These motifs are able to self-cleave a specific phosphodiester bond on an mRNA molecule, lower eukaryotes and a few bacteria contain group I and group II ribozymes. These motifs can self-splice by cleaving and joining together phosphodiester bonds, the general catalytic mechanism used by ribozymes is similar to the mechanism used by protein ribonucleases. This catalytic mechanism has been used by scientists to perform sequence-specific cleavage of target mRNA molecules
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Gene
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A gene is a locus of DNA which is made up of nucleotides and is the molecular unit of heredity. The transmission of genes to an offspring is the basis of the inheritance of phenotypic traits. These genes make up different DNA sequences called genotypes, genotypes along with environmental and developmental factors determine what the phenotypes will be. Most biological traits are under the influence of polygenes as well as gene–environment interactions, genes can acquire mutations in their sequence, leading to different variants, known as alleles, in the population. These alleles encode slightly different versions of a protein, which cause different phenotypical traits, usage of the term having a gene typically refers to containing a different allele of the same, shared gene. Genes evolve due to natural selection or survival of the fittest of the alleles, the concept of a gene continues to be refined as new phenomena are discovered. For example, regulatory regions of a gene can be far removed from its coding regions, some viruses store their genome in RNA instead of DNA and some gene products are functional non-coding RNAs. The existence of discrete inheritable units was first suggested by Gregor Mendel, from 1857 to 1864, in Brno, he studied inheritance patterns in 8000 common edible pea plants, tracking distinct traits from parent to offspring. He described these mathematically as 2n combinations where n is the number of differing characteristics in the original peas, although he did not use the term gene, he explained his results in terms of discrete inherited units that give rise to observable physical characteristics. This description prefigured the distinction between genotype and phenotype, charles Darwin developed a theory of inheritance he termed pangenesis, from Greek pan and genesis / genos. Darwin used the term gemmule to describe hypothetical particles that would mix during reproduction, de Vries called these units pangenes, after Darwins 1868 pangenesis theory. In 1909 the Danish botanist Wilhelm Johannsen shortened the name to gene, advances in understanding genes and inheritance continued throughout the 20th century. Deoxyribonucleic acid was shown to be the repository of genetic information by experiments in the 1940s to 1950s. In the early 1950s the prevailing view was that the genes in a chromosome acted like discrete entities, indivisible by recombination, collectively, this body of research established the central dogma of molecular biology, which states that proteins are translated from RNA, which is transcribed from DNA. This dogma has since shown to have exceptions, such as reverse transcription in retroviruses. The modern study of genetics at the level of DNA is known as molecular genetics, in 1972, Walter Fiers and his team at the University of Ghent were the first to determine the sequence of a gene, the gene for Bacteriophage MS2 coat protein. The subsequent development of chain-termination DNA sequencing in 1977 by Frederick Sanger improved the efficiency of sequencing, an automated version of the Sanger method was used in early phases of the Human Genome Project. The theories developed in the 1930s and 1940s to integrate molecular genetics with Darwinian evolution are called the evolutionary synthesis
36.
Drosophila
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One species of Drosophila in particular, D. melanogaster, has been heavily used in research in genetics and is a common model organism in developmental biology. The terms fruit fly and Drosophila are often used synonymously with D. melanogaster in modern biological literature, the entire genus, however, contains more than 1,500 species and is very diverse in appearance, behavior, and breeding habitat. The term Drosophila, meaning dew-loving, is a modern scientific Latin adaptation from Greek words δρόσος, drósos, dew, Drosophila species are small flies, typically pale yellow to reddish brown to black, with red eyes. Many species, including the noted Hawaiian picture-wings, have distinct black patterns on the wings, the plumose arista, bristling of the head and thorax, and wing venation are characters used to diagnose the family. Most are small, about 2–4 mm long, but some, Drosophila species are found all around the world, with more species in the tropical regions. They can be found in deserts, tropical rainforest, cities, swamps, most species breed in various kinds of decaying plant and fungal material, including fruit, bark, slime fluxes, flowers, and mushrooms. The larvae of at least one species, D. suzukii, can feed in fresh fruit. A few species have switched to being parasites or predators, many species can be attracted to baits of fermented bananas or mushrooms, but others are not attracted to any kind of baits. Males may congregate at patches of suitable breeding substrate to compete for the females, or form leks, several Drosophila species, including D. melanogaster, D. immigrans, and D. simulans, are closely associated with humans, and are often referred to as domestic species. These and other species have been introduced around the world by human activities such as fruit transports. Males of this genus are known to have the longest sperm cells of any studied organism on Earth, including one species, Drosophila bifurca, the cells are mostly tail, and are delivered to the females in tangled coils. The other members of the genus Drosophila also make relatively few giant sperm cells, D. melanogaster sperm cells are a more modest 1.8 mm long, although this is still about 35 times longer than a human sperm. Several species in the D. melanogaster species group are known to mate by traumatic insemination, Drosophila species vary widely in their reproductive capacity. Those such as D. melanogaster that breed in large, relatively rare resources have ovaries that mature 10–20 eggs at a time, others that breed in more-abundant but less nutritious substrates, such as leaves, may only lay one egg per day. The eggs have one or more respiratory filaments near the anterior end, larvae feed not on the vegetable matter itself, but on the yeasts and microorganisms present on the decaying breeding substrate. Development time varies widely between species and depends on the factors such as temperature, breeding substrate, and crowding. Numerous studies have shown that fruit flies lay eggs using an environmental circle, if fruit flies laid eggs at nighttime during which the environmental conditions were advantageous, the eggs could not be susceptible to desiccation from parasites. As a result, the offspring reproduced from these eggs would have greater fitness compared to offspring that were reproduced from eggs laid during the day, since eggs are laid with a biological clock, D. melanogaster became adaptive to their environmental cycles, which showed a major advantage
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Pesticide resistance
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Pesticide resistance describes the decreased susceptibility of a pest population to a pesticide that was previously effective at controlling the pest. Pest species evolve pesticide resistance via natural selection, the most resistant specimens survive, farmers in the USA lost 7% of their crops to pests in the 1940s, over the 1980s and 1990s, the loss was 13%, even though more pesticides were being used. Over 500 species of pests have evolved a resistance to a pesticide, other sources estimate the number to be around 1000 species since 1945. For example, the northern corn rootworm became adapted to a crop rotation by spending the year when field is planted to soybeans in a diapause. As of 2014 few new weed killers are near commercialization, and none with a novel, pesticide resistance probably stems from multiple factors, Many pest species produce large broods. This increases the probability of mutations and ensures the rapid expansion of resistant populations, pest species had been exposed to natural toxins long before agriculture began. For example, many plants produce phytotoxins to protect them from herbivores, as a result, coevolution of herbivores and their host plants required development of the physiological capability to detoxify or tolerate poisons. Humans often rely almost exclusively on pesticides for pest control and this increases selection pressure towards resistance. Pesticides that fail to break down quickly contribute to selection for resistant strains even after they are no longer being applied, in response to resistance, managers may increase pesticide quantities/frequency, which exacerbates the problem. In addition, some pesticides are toxic toward species that feed on or compete with pests and this can allow the pest population to expand, requiring more pesticides. This is sometimes referred to as trap, or a pesticide treadmill. Insect predators and parasites generally have smaller populations and are likely to evolve resistance than are pesticides primary targets, such as mosquitoes. Weakening them allows the pests to flourish, alternatively, resistant predators can be bred in laboratories. Pests with limited diets are likely to evolve resistance, because they are exposed to higher pesticide concentrations and has less opportunity to breed with unexposed populations. Pests with shorter generation times develop resistance more quickly than others, Resistance has evolved in multiple species, Resistance to insecticides was first documented by A. L. Melander in 1914 when scale insects demonstrated resistance to an inorganic insecticide. Between 1914 and 1946,11 additional cases were recorded, the development of organic insecticides, such as DDT, gave hope that insecticide resistance was a dead issue. However, by 1947 housefly resistance to DDT had evolved, in the US, studies have shown that fruit flies that infest orange groves were becoming resistant to malathion. In Hawaii, Japan and Tennessee, the diamondback moth evolved a resistance to Bacillus thuringiensis about three years after it began to be used heavily
38.
Enzyme
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Enzymes /ˈɛnzaɪmz/ are macromolecular biological catalysts. Enzymes accelerate, or catalyze, chemical reactions, the molecules at the beginning of the process upon which enzymes may act are called substrates and the enzyme converts these into different molecules, called products. Almost all metabolic processes in the cell need enzymes in order to occur at rates fast enough to sustain life, the set of enzymes made in a cell determines which metabolic pathways occur in that cell. The study of enzymes is called enzymology, enzymes are known to catalyze more than 5,000 biochemical reaction types. Most enzymes are proteins, although a few are catalytic RNA molecules, enzymes specificity comes from their unique three-dimensional structures. Like all catalysts, enzymes increase the rate of a reaction by lowering its activation energy, some enzymes can make their conversion of substrate to product occur many millions of times faster. An extreme example is orotidine 5-phosphate decarboxylase, which allows a reaction that would take millions of years to occur in milliseconds. Chemically, enzymes are like any catalyst and are not consumed in chemical reactions, enzymes differ from most other catalysts by being much more specific. Enzyme activity can be affected by other molecules, inhibitors are molecules that decrease enzyme activity, many drugs and poisons are enzyme inhibitors. An enzymes activity decreases markedly outside its optimal temperature and pH, some enzymes are used commercially, for example, in the synthesis of antibiotics. French chemist Anselme Payen was the first to discover an enzyme, diastase and he wrote that alcoholic fermentation is an act correlated with the life and organization of the yeast cells, not with the death or putrefaction of the cells. In 1877, German physiologist Wilhelm Kühne first used the term enzyme, the word enzyme was used later to refer to nonliving substances such as pepsin, and the word ferment was used to refer to chemical activity produced by living organisms. Eduard Buchner submitted his first paper on the study of yeast extracts in 1897, in a series of experiments at the University of Berlin, he found that sugar was fermented by yeast extracts even when there were no living yeast cells in the mixture. He named the enzyme that brought about the fermentation of sucrose zymase, in 1907, he received the Nobel Prize in Chemistry for his discovery of cell-free fermentation. Following Buchners example, enzymes are usually named according to the reaction they carry out, the biochemical identity of enzymes was still unknown in the early 1900s. Sumner showed that the enzyme urease was a protein and crystallized it. These three scientists were awarded the 1946 Nobel Prize in Chemistry, the discovery that enzymes could be crystallized eventually allowed their structures to be solved by x-ray crystallography. This high-resolution structure of lysozyme marked the beginning of the field of structural biology, an enzymes name is often derived from its substrate or the chemical reaction it catalyzes, with the word ending in -ase
39.
Myrosinase
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Myrosinase is a family of enzymes involved in plant defense against herbivores. The three-dimensional structure has been elucidated and is available in the PDB, a member of the glycoside hydrolase family, myrosinase possesses several similarities with the more ubiquitous O-glycosidases. However, myrosinase is the only known enzyme found in nature that can cleave a thio-linked glucose and its known biological function is to catalyze the hydrolysis of a class of compounds called glucosinolates. Myrosinase is regarded as an enzyme and is capable of hydrolyzing glucosinolates into various compounds. Myrosinase catalyzes the reaction a thioglucoside + H2O ⇌ a sugar + a thiol Thus. In the presence of water, myrosinase cleaves off the group from a glucosinolate. The remaining molecule then quickly converts to a thiocyanate, an isothiocyanate, or a nitrile, the hydrolysis of glucosinolates by myrosinase can yield a variety of products, depending on various physiological conditions such as pH and the presence of certain cofactors. All known reactions have been observed to share the initial steps. First, the linkage is cleaved by myrosinase, releasing D-glucose. The resulting aglycone undergoes a spontaneous Lossen-like rearrangement, releasing a sulfate, the last step in the mechanism is subject to the greatest variety depending on the physiological conditions under which the reaction takes place. At neutral pH, the product is the isothiocyanate. Under acidic conditions, and in the presence of ions or epithiospecifer proteins. Ascorbate is a cofactor of myrosinase, serving as a base catalyst in glucosinolate hydrolysis. Sulfate, a byproduct of glucosinolate hydrolysis, has identified as a competitive inhibitor of myrosinase. Myrosinase exists as a dimer with subunits of 60-70 kDa each, x-ray crystallography of myrosinase isolated from Sinapis alba revealed the two subunits are linked by a zinc atom. A feature of many ß-glucosidases are catalytic glutamate residues at their active sites, ascorbate has been shown to substitute for the activity of the glutamate residues. Myrosinase and its substrate, glucosinolate, are known to be part of the plant’s defense response. The glucosinolate-myrosinase defensive system is packaged in the plant in a unique manner, plants store myrosinase glucosinolates by compartmentalization, such that the latter is released and activated only when the plant is under attack
40.
Glucosinolate
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The glucosinolates are natural components of many pungent plants such as mustard, cabbage, and horseradish. The pungency of those plants is due to mustard oils produced from glucosinolates when the plant material is chewed, cut, glucosinolates constitute a natural class of organic compounds that contain sulfur and nitrogen and are derived from glucose and an amino acid. They are water-soluble anions and can be leached into the water during cooking, every glucosinolate contains a central carbon atom, which is bound via a sulfur atom to the thioglucose group and via a nitrogen atom to a sulfate group. For example, glucosinolates occur in cabbages, watercress, horseradish, capers and they are typically in parts consumed, with the pungent taste of these vegetables due to breakdown products of glucosinolates. The glucosinolates are also found in the seeds of these plants, about 132 different glucosinolates are known to occur naturally in plants. They are synthesized from amino acids, So-called aliphatic glucosinolates derived from mainly methionine. The plants contain the enzyme myrosinase, which, in the presence of water, the remaining molecule then quickly converts to an isothiocyanate, a nitrile, or a thiocyanate, these are the active substances that serve as defense for the plant. Glucosinolates are also called mustard oil glycosides, the standard product of the reaction is the isothiocyanate, the other two products mainly occur in the presence of specialised plant proteins that alter the outcome of the reaction. To prevent damage to the plant itself, the myrosinase and glucosinolates are stored in compartments of the cell. Some glucosinolates have been shown to have effects in both humans and animals at high doses. However, tolerance level to glucosinolates varies even within the same genus, the glucosinolate sinigrin, among others, was shown to be responsible for the bitterness of cooked cauliflower and Brussels sprouts. Glucosinolate have been shown to alter animal eating behavior, most recently, a randomized controlled study evaluating the effects of broccoli seed supplementation on autism spectrum disorder is underway. The makeup of glucosinolates and their hydrolysis products varies by vegetable, substances derived from plants producing large amounts of glucosinolates can serve as natural pesticides. For instance, the white butterfly oviposits its eggs on these glucosinolate-containing plants because they help the larvae survive. The biochemical basis of these specialisations are being unraveled, the whites and orange tips all possess the so-called nitrile specifier protein, which diverts glucosinolate hydrolysis toward nitriles rather than reactive isothiocyanates. Other kinds of insects sequester glucosinolates, in specialised aphids, but not in sawflies, a distinct animal-myrosinase is found in muscle tissue, leading to degradation of sequestered glucosinolates upon aphid tissue destruction. This diverse panel of biochemical solutions to the same plant chemical plays a key role in current attempts to understand the evolution of plant-insect relationships, isothiocyanate Gluconasturtiin Glucobrassicin Progoitrin Sinigrin Sinalbin Glucosinolate metabolism pathways from MetaCyc
41.
Herbivore
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A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthparts adapted to rasping or grinding, horses and other herbivores have wide flat teeth that are adapted to grinding grass, tree bark, and other tough plant material. A large percentage of herbivores have mutualistic gut flora that help them digest plant matter and this gut flora is made up of cellulose-digesting protozoans or bacteria living in the herbivores intestines. Herbivore is the form of a modern Latin coinage, herbivora. Richard Owen employed the term in an 1854 work on fossil teeth. Herbivora is derived from the Latin herba meaning a small plant or herb, Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms feed on autotrophs in general are known as primary consumers. Herbivory usually refers to eating plants, fungi, bacteria and protists that feed on living plants are usually termed plant pathogens. Flowering plants that obtain nutrition from other living plants are usually termed parasitic plants, there is however no single exclusive and definitive ecological classification of consumption patterns, each textbook has its own variations on the theme. Insects fed on the spores of early Devonian plants, and the Rhynie chert also provides evidence that organisms fed on plants using a pierce, during the next 75 million years, plants evolved a range of more complex organs, such as roots and seeds. There is no evidence of any organism being fed upon until the middle-late Mississippian,330.9 million years ago, further than their arthropod status, the identity of these early herbivores is uncertain. Hole feeding and skeletonisation are recorded in the early Permian, with surface fluid feeding evolving by the end of that period, Herbivory among four-limbed terrestrial vertebrates, the tetrapods developed in the Late Carboniferous. Early tetrapods were large amphibious piscivores, while amphibians continued to feed on fish and insects, some reptiles began exploring two new food types, tetrapods and plants. The entire dinosaur order ornithischia was composed with herbivores dinosaurs, carnivory was a natural transition from insectivory for medium and large tetrapods, requiring minimal adaptation. In contrast, a set of adaptations was necessary for feeding on highly fibrous plant materials. Arthropods evolved herbivory in four phases, changing their approach to it in response to changing plant communities, tetrapod herbivores made their first appearance in the fossil record of their jaws near the Permio-Carboniferous boundary, approximately 300 million years ago. The earliest evidence of their herbivory has been attributed to dental occlusion, the evolution of dental occlusion led to a drastic increase in plant food processing and provides evidence about feeding strategies based on tooth wear patterns. Examination of phylogenetic frameworks of tooth and jaw morphologes has revealed that dental occlusion developed independently in several lineages tetrapod herbivores and this suggests that evolution and spread occurred simultaneously within various lineages
42.
Allyl isothiocyanate
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Allyl isothiocyanate is the organosulfur compound with the formula CH2CHCH2NCS. This colorless oil is responsible for the pungent taste of mustard, radish, horseradish and this pungency and the lachrymatory effect of AITC is mediated through the TRPA1 and TRPV1 ion channels. It is slightly soluble in water, but more soluble in most organic solvents, allyl isothiocyanate can be obtained from the seeds of black mustard or brown Indian mustard. When these mustard seeds are broken, the enzyme myrosinase is released, when an animal chews the plant, the allyl isothiocyanate is released, repelling the animal. Allyl isothiocyanate can also be liberated by dry distillation of the seeds, the product obtained in this fashion is known as volatile oil of mustard and is usually around 92% pure. It is used principally as an agent in foods. Synthetic allyl isothiocyanate is used as an insecticide, bacteriocide, and nematocide, hydrolysis of allyl isothiocyanate gives allylamine. Allyl isothiocyanate has an LD50 of 151 mg/kg and is a lachrymator, based on in vitro experiments and animal models, allyl isothiocyanate exhibits many of the desirable attributes of a cancer chemopreventive agent
43.
Horseradish
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Horseradish is a perennial plant of the Brassicaceae family. It is a root used as a spice. The plant is native to southeastern Europe and western Asia. It is now popular around the world and it grows up to 1.5 meters tall, and is cultivated primarily for its large, white, tapered root. The intact horseradish root has hardly any aroma, when cut or grated, however, enzymes from the now-broken plant cells break down sinigrin to produce allyl isothiocyanate, which irritates the mucous membranes of the sinuses and eyes. Grated mash should be used immediately or preserved in vinegar for best flavor, once exposed to air or heat it will begin to lose its pungency, darken in color, and become unpleasantly bitter tasting over time. Horseradish is probably indigenous to temperate Eastern Europe, where its Slavic name chren seemed to Augustin Pyramus de Candolle more primitive than any Western synonym, Horseradish has been cultivated since antiquity. According to Greek mythology, the Delphic Oracle told Apollo that the horseradish was worth its weight in gold, the early Renaissance herbalists Pietro Andrea Mattioli and John Gerard showed it under Raphanus. Though its modern Linnaean genus Armoracia was first applied to it by Heinrich Bernhard Ruppius, in his Flora Jenensis,1745, Linnaeus called it Coclearia armoracia. Both root and leaves were used as a medicine during the Middle Ages and the root was used as a condiment on meats in Germany, Scandinavia and it was introduced to North America during European colonialization, both George Washington and Thomas Jefferson mention horseradish in garden accounts. William Turner mentions horseradish as Red Cole in his Herbal, in The Herball, or Generall Historie of Plantes, John Gerard describes it under the name of raphanus rusticanus, stating that it occurs wild in several parts of England. The word horseradish is attested in English from the 1590s and it combines the word horse and the word radish. After the first frost in the autumn kills the leaves, the root is dug, the main root is harvested and one or more large offshoots of the main root are replanted to produce next years crop. Horseradish left undisturbed in the garden spreads via underground shoots and can become invasive, older roots left in the ground become woody, after which they are no longer culinarily useful, although older plants can be dug and re-divided to start new plants. The early season leaves can be different, asymmetric spiky. Widely introduced by accident, cabbageworms, the larvae of Pieris rapae, the adults are white butterflies with black spots on the forewings that are commonly seen flying around plants during the day. The caterpillars are velvety green with faint yellow stripes running lengthwise down the back, full grown caterpillars are about 1-inch in length. They overwinter in green pupal cases, adults start appearing in gardens after the last frost and are a problem through the remainder of the growing season
. PMID 22544984. Archived from the original on 24 May 2013.
