Wikispecies is a wiki-based online project supported by the Wikimedia Foundation. Its aim is to create a comprehensive free content catalogue of all species. Jimmy Wales stated that editors are not required to fax in their degrees, but that submissions will have to pass muster with a technical audience. Wikispecies is available under the GNU Free Documentation License and CC BY-SA 3.0. Started in September 2004, with biologists across the world invited to contribute, the project had grown a framework encompassing the Linnaean taxonomy with links to Wikipedia articles on individual species by April 2005. Benedikt Mandl co-ordinated the efforts of several people who are interested in getting involved with the project and contacted potential supporters in early summer 2004. Databases were evaluated and the administrators contacted, some of them have agreed on providing their data for Wikispecies. Mandl defined two major tasks: Figure out how the contents of the data base would need to be presented—by asking experts, potential non-professional users and comparing that with existing databases Figure out how to do the software, which hardware is required and how to cover the costs—by asking experts, looking for fellow volunteers and potential sponsorsAdvantages and disadvantages were discussed by the wikimedia-I mailing list.
The board of directors of the Wikimedia Foundation voted by 4 to 0 in favor of the establishment of a Wikispecies. The project is hosted at species.wikimedia.org. It was merged to a sister project of Wikimedia Foundation on September 14, 2004. On October 10, 2006, the project exceeded 75,000 articles. On May 20, 2007, the project exceeded 100,000 articles with a total of 5,495 registered users. On September 8, 2008, the project exceeded 150,000 articles with a total of 9,224 registered users. On October 23, 2011, the project reached 300,000 articles. On June 16, 2014, the project reached 400,000 articles. On January 7, 2017, the project reached 500,000 articles. On October 30, 2018, the project reached 600,000 articles, a total of 1.12 million pages. Wikispecies comprises taxon pages, additionally pages about synonyms, taxon authorities, taxonomical publications, institutions or repositories holding type specimen. Wikispecies asks users to use images from Wikimedia Commons. Wikispecies does not allow the use of content.
All Species Foundation Catalogue of Life Encyclopedia of Life Tree of Life Web Project List of online encyclopedias The Plant List Wikispecies, The free species directory that anyone can edit Species Community Portal The Wikispecies Charter, written by Wales
Spiral bacteria, bacteria of spiral shape, form the third major morphological category of prokaryotes along with the rod-shaped bacilli and round cocci. Spiral bacteria can be subclassified by the number of twists per cell, cell thickness, cell flexibility, motility; the two types of spiral cells are spirillum and spirochete, with spirillum being rigid with external flagella, spirochetes being flexible with internal flagella. A spirillum is a rigid spiral bacterium, Gram-negative and has external amphitrichous or lophotrichous flagella. Examples include: Members of the genus Spirillum Campylobacter species, such as Campylobacter jejuni, a foodborne pathogen that causes campylobacteriosis Helicobacter species, such as Helicobacter pylori, a cause of peptic ulcers A spirochete is a thin, flexible, spiral bacteria, motile via internal periplasmic flagella inside the outer membrane. Owing to their morphological properties, spirochetes are difficult to Gram-stain but may be visualized using dark field microscopy or Warthin–Starry stain.
Examples include: Members of the phylum Spirochaetes Leptospira species. Borrelia species, such as Borrelia burgdorferi, a tick-borne bacterium that causes Lyme disease Treponema species, such as Treponema pallidum, subspecies of which causes treponematoses, including syphilis
In cell biology, the cytoplasm is all of the material within a cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm; the main components of the cytoplasm are cytosol – a gel-like substance, the organelles – the cell's internal sub-structures, various cytoplasmic inclusions. The cytoplasm is about 80% water and colorless; the submicroscopic ground cell substance, or cytoplasmatic matrix which remains after exclusion the cell organelles and particles is groundplasm. It is the hyaloplasm of light microscopy, high complex, polyphasic system in which all of resolvable cytoplasmic elements of are suspended, including the larger organelles such as the ribosomes, the plant plastids, lipid droplets, vacuoles. Most cellular activities take place within the cytoplasm, such as many metabolic pathways including glycolysis, processes such as cell division; the concentrated inner area is called the endoplasm and the outer layer is called the cell cortex or the ectoplasm.
Movement of calcium ions in and out of the cytoplasm is a signaling activity for metabolic processes. In plants, movement of the cytoplasm around vacuoles is known as cytoplasmic streaming; the term was introduced by Rudolf von Kölliker in 1863 as a synonym for protoplasm, but it has come to mean the cell substance and organelles outside the nucleus. There has been certain disagreement on the definition of cytoplasm, as some authors prefer to exclude from it some organelles the vacuoles and sometimes the plastids; the physical properties of the cytoplasm have been contested in recent years. It remains uncertain how the varied components of the cytoplasm interact to allow movement of particles and organelles while maintaining the cell’s structure; the flow of cytoplasmic components plays an important role in many cellular functions which are dependent on the permeability of the cytoplasm. An example of such function is cell signalling, a process, dependent on the manner in which signaling molecules are allowed to diffuse across the cell.
While small signaling molecules like calcium ions are able to diffuse with ease, larger molecules and subcellular structures require aid in moving through the cytoplasm. The irregular dynamics of such particles have given rise to various theories on the nature of the cytoplasm. There has long been evidence, it is thought that the component molecules and structures of the cytoplasm behave at times like a disordered colloidal solution and at other times like an integrated network, forming a solid mass. This theory thus proposes that the cytoplasm exists in distinct fluid and solid phases depending on the level of interaction between cytoplasmic components, which may explain the differential dynamics of different particles observed moving through the cytoplasm, it has been proposed that the cytoplasm behaves like a glass-forming liquid approaching the glass transition. In this theory, the greater the concentration of cytoplasmic components, the less the cytoplasm behaves like a liquid and the more it behaves as a solid glass, freezing larger cytoplasmic components in place.
A cell's ability to vitrify in the absence of metabolic activity, as in dormant periods, may be beneficial as a defence strategy. A solid glass cytoplasm would freeze subcellular structures in place, preventing damage, while allowing the transmission of small proteins and metabolites, helping to kickstart growth upon the cell's revival from dormancy. There has been research examining the motion of cytoplasmic particles independent of the nature of the cytoplasm. In such an alternative approach, the aggregate random forces within the cell caused by motor proteins explain the non-Brownian motion of cytoplasmic constituents; the three major elements of the cytoplasm are the cytosol and inclusions. The cytosol is the portion of the cytoplasm not contained within membrane-bound organelles. Cytosol makes up about 70% of the cell volume and is a complex mixture of cytoskeleton filaments, dissolved molecules, water; the cytosol's filaments include the protein filaments such as actin filaments and microtubules that make up the cytoskeleton, as well as soluble proteins and small structures such as ribosomes and the mysterious vault complexes.
The inner and more fluid portion of the cytoplasm is referred to as endoplasm. Due to this network of fibres and high concentrations of dissolved macromolecules, such as proteins, an effect called macromolecular crowding occurs and the cytosol does not act as an ideal solution; this crowding effect alters. Organelles, are membrane-bound structures inside the cell that have specific functions; some major organelles that are suspended in the cytosol are the mitochondria, the endoplasmic reticulum, the Golgi apparatus, lysosomes, in plant cells, chloroplasts. The inclusions are small particles of insoluble substances suspended in the cytosol. A huge range of inclusions exist in different cell types, range from crystals of calcium oxalate or silicon dioxide in plants, to granules of energy-storage materials such as starch, glycogen, or polyhydroxybutyrate. A widespread example are lipid droplets, which are spherical droplets composed of lipids and proteins that are used in both prokaryotes and eukaryotes as a way of storing lipids such as fatty acids and sterols.
Lipid droplets make up much of the volume of adipocytes, which are specialized lipid-st
Earth's magnetic field
Earth's magnetic field known as the geomagnetic field, is the magnetic field that extends from the Earth's interior out into space, where it interacts with the solar wind, a stream of charged particles emanating from the Sun. The magnetic field, is generated by electric currents due to the motion of convection currents of molten iron in the Earth's outer core: these convection currents are caused by heat escaping from the core, a natural process called a geodynamo; the magnitude of the Earth's magnetic field at its surface ranges from 25 to 65 microteslas. As an approximation, it is represented by a field of a magnetic dipole tilted at an angle of about 11 degrees with respect to Earth's rotational axis, as if there were a bar magnet placed at that angle at the center of the Earth; the North geomagnetic pole located near Greenland in the northern hemisphere, is the south pole of the Earth's magnetic field, conversely. While the North and South magnetic poles are located near the geographic poles and continuously move over geological time scales, but sufficiently for ordinary compasses to remain useful for navigation.
However, at irregular intervals averaging several hundred thousand years, the Earth's field reverses and the North and South Magnetic Poles abruptly switch places. These reversals of the geomagnetic poles leave a record in rocks that are of value to paleomagnetists in calculating geomagnetic fields in the past; such information in turn is helpful in studying the motions of continents and ocean floors in the process of plate tectonics. The magnetosphere is the region above the ionosphere, defined by the extent of the Earth's magnetic field in space, it extends several tens of thousands of kilometers into space, protecting the Earth from the charged particles of the solar wind and cosmic rays that would otherwise strip away the upper atmosphere, including the ozone layer that protects the Earth from harmful ultraviolet radiation. The Earth's magnetic field serves to deflect most of the solar wind, whose charged particles would otherwise strip away the ozone layer that protects the Earth from harmful ultraviolet radiation.
One stripping mechanism is for gas to be caught in bubbles of magnetic field, which are ripped off by solar winds. Calculations of the loss of carbon dioxide from the atmosphere of Mars, resulting from scavenging of ions by the solar wind, indicate that the dissipation of the magnetic field of Mars caused a near total loss of its atmosphere; the study of past magnetic field of the Earth is known as paleomagnetism. The polarity of the Earth's magnetic field is recorded in igneous rocks, reversals of the field are thus detectable as "stripes" centered on mid-ocean ridges where the sea floor is spreading, while the stability of the geomagnetic poles between reversals has allowed paleomagnetists to track the past motion of continents. Reversals provide the basis for magnetostratigraphy, a way of dating rocks and sediments; the field magnetizes the crust, magnetic anomalies can be used to search for deposits of metal ores. Humans have used compasses for direction finding since the 11th century A.
D. and for navigation since the 12th century. Although the magnetic declination does shift with time, this wandering is slow enough that a simple compass remains useful for navigation. Using magnetoreception various other organisms, ranging from some types of bacteria to pigeons, use the Earth's magnetic field for orientation and navigation. At any location, the Earth's magnetic field can be represented by a three-dimensional vector. A typical procedure for measuring its direction is to use a compass to determine the direction of magnetic North, its angle relative to true North is the variation. Facing magnetic North, the angle the field makes with the horizontal is the inclination or magnetic dip; the intensity of the field is proportional to the force. Another common representation is in Y and Z coordinates; the intensity of the field is measured in gauss, but is reported in nanoteslas, with 1 G = 100,000 nT. A nanotesla is referred to as a gamma; the tesla is the SI unit of the magnetic field, B.
The Earth's field ranges between 25,000 and 65,000 nT. By comparison, a strong refrigerator magnet has a field of about 10,000,000 nanoteslas. A map of intensity contours is called an isodynamic chart; as the World Magnetic Model shows, the intensity tends to decrease from the poles to the equator. A minimum intensity occurs in the South Atlantic Anomaly over South America while there are maxima over northern Canada and the coast of Antarctica south of Australia; the inclination is given by an angle that can assume values between -90° to 90°. In the northern hemisphere, the field points downwards, it is straight down at the North Magnetic Pole and rotates upwards as the latitude decreases until it is horizontal at the magnetic equator. It continues to rotate upwards. Inclination can be measured with a dip circle. An isoclinic chart for the Earth's magnetic field is shown below. Declination is positive for an eastward deviation of the field relative to true north, it can be estimated by comparing the magnetic north/south heading on a compass with the direction of a celestial pole.
Maps include information on the declination as an angle or a small diagram showing the relationship between magnetic north and true north. Information on declination for a region can be represented by a chart with isogonic lines. Components of the Earth's
Magnetite is a rock mineral and one of the main iron ores, with the chemical formula Fe3O4. It is one of the oxides of iron, is ferrimagnetic, it is the most magnetic of all the naturally-occurring minerals on Earth. Naturally-magnetized pieces of magnetite, called lodestone, will attract small pieces of iron, how ancient peoples first discovered the property of magnetism. Today it is mined as iron ore. Small grains of magnetite occur in all igneous and metamorphic rocks. Magnetite is black or brownish-black with a metallic luster, has a Mohs hardness of 5–6 and leaves a black streak; the chemical IUPAC name is iron oxide and the common chemical name is ferrous-ferric oxide. In addition to igneous rocks, magnetite occurs in sedimentary rocks, including banded iron formations and in lake and marine sediments as both detrital grains and as magnetofossils. Magnetite nanoparticles are thought to form in soils, where they oxidize to maghemite; the chemical composition of magnetite is Fe2+Fe23+O42−. The main details of its structure were established in 1915.
It was one of the first crystal structures to be obtained using X-ray diffraction. The structure is inverse spinel, with O2− ions forming a face centered cubic lattice and iron cations occupying interstitial sites. Half of the Fe3+ cations occupy tetrahedral sites while the other half, along with Fe2+ cations, occupy octahedral sites; the unit cell consists of 32 O2− ions and unit cell length is a = 0.839 nm. Magnetite contains both ferrous and ferric iron, requiring environments containing intermediate levels of oxygen availability to form. Magnetite differs from most other iron oxides in that it contains both trivalent iron; as a member of the spinel group, magnetite can form solid solutions with structured minerals, including ulvospinel and chromite. Titanomagnetite known as titaniferous magnetite, is a solid solution between magnetite and ulvospinel that crystallizes in many mafic igneous rocks. Titanomagnetite may undergo oxyexsolution during cooling, resulting in ingrowths of magnetite and ilmenite.
Natural and synthetic magnetite occurs most as octahedral crystals bounded by planes and as rhombic-dodecahedra. Twinning occurs on the plane. Hydrothermal synthesis produce single octahedral crystals which can be as large as 10mm across. In the presence of mineralizers such as 0.1M HI or 2M NH4Cl and at 0.207 MPa at 416-800 °C, magnetite grew as crystals whose shapes were a combination of rhombic-dodechahedra forms. The crystals were more rounded than usual; the appearance of higher forms was considered as a result from a decrease in the surface energies caused by the lower surface to volume ratio in the rounded crystals. Magnetite has been important in understanding the conditions. Magnetite reacts with oxygen to produce hematite, the mineral pair forms a buffer that can control oxygen fugacity. Igneous rocks contain solid solutions of both titanomagnetite and hemoilmenite or titanohematite. Compositions of the mineral pairs are used to calculate how oxidizing was the magma: a range of oxidizing conditions are found in magmas and the oxidation state helps to determine how the magmas might evolve by fractional crystallization.
Magnetite is produced from peridotites and dunites by serpentinization. Lodestones were used as an early form of magnetic compass. Magnetite carries the dominant magnetic signature in rocks, so it has been a critical tool in paleomagnetism, a science important in understanding plate tectonics and as historic data for magnetohydrodynamics and other scientific fields; the relationships between magnetite and other iron oxide minerals such as ilmenite and ulvospinel have been much studied. At low temperatures, magnetite undergoes a crystal structure phase transition from a monoclinic structure to a cubic structure known as the Verwey transition. Optical studies show that this metal to insulator transition is sharp and occurs around 120 K; the Verwey transition is dependent on grain size, domain state and the iron-oxygen stoichiometry. An isotropic point occurs near the Verwey transition around 130 K, at which point the sign of the magnetocrystalline anisotropy constant changes from positive to negative.
The Curie temperature of magnetite is 858 K. If magnetite is in a large enough quantity it can be found in aeromagnetic surveys using a magnetometer which measures magnetic intensities. Magnetite is sometimes found in large quantities in beach sand; such black sands are found in various places, such as Lung Kwu Tan of Hong Kong. The magnetite, eroded from rocks, is carried to the beach by rivers and concentrated by wave action and currents. Huge deposits have been found in banded iron formations; these sedimentary rocks have been used to infer changes in the oxygen content of the atmosphere of the Earth. Remote sensing has the potential to be a big part in locating magnetite sands as small amounts of magnetite in sand can drastically alter the sands albedo, the amount of electromagnetic radiation the sand will reflect; the darker magnetite will lower the sands albedo compared to sands. Large deposits of magnetite are found in the Atacama region of Chile.
Proteobacteria is a major phylum of gram-negative bacteria. They include a wide variety of pathogens, such as Escherichia, Vibrio, Yersinia and many other notable genera. Others include many of the bacteria responsible for nitrogen fixation. Carl Woese established this grouping in 1987, calling it informally the "purple bacteria and their relatives"; because of the great diversity of forms found in this group, it was named after Proteus, a Greek god of the sea capable of assuming many different shapes and is not named after the Proteobacteria genus Proteus. Some Alphaproteobacteria can grow at low levels of nutrients and have unusual morphology such as stalks and buds. Others include agriculturally important bacteria capable of inducing nitrogen fixation in symbiosis with plants; the type order is the Caulobacterales. The Betaproteobacteria are metabolically diverse and contain chemolithoautotrophs and generalist heterotrophs; the type order is the Burkholderiales, comprising an enormous range of metabolic diversity, including opportunistic pathogens.
The Hydrogenophilalia are obligate include heterotrophs and autotrophs. The type order is the Hydrogenophilales; the Gammaproteobacteria are the largest class in terms of species with validly published names. The type order is the Pseudomonadales, which include the genera Pseudomonas and the nitrogen-fixing Azotobacter; the Acidithiobacillia contain only sulfur and uranium-oxidising autotrophs. The type order is the Acidithiobacillales, which includes economically important organisms used in the mining industry such as Acidithiobacillus spp; the Deltaproteobacteria include bacteria that are predators on other bacteria and are important contributors to the anaerobic side of the sulfur cycle. The type order is the Myxococcales, which includes organisms with self-organising abilities such as Myxococcus spp; the Epsilonproteobacteria are slender, Gram-negative rods that are helical or curved. The type order is the Campylobacterales, which includes important food pathogens such as Campylobacter spp.
The Oligoflexia are filamentous aerobes. The type order is the Oligoflexales. All "Proteobacteria" are Gram-negative, with an outer membrane composed of lipopolysaccharides. Many move about using flagella; the latter include the myxobacteria, an order of bacteria that can aggregate to form multicellular fruiting bodies. A wide variety in the types of metabolism exists. Most members are facultatively or obligately anaerobic, chemolithoautotrophic, heterotrophic, but numerous exceptions occur. A variety of genera, which are not related to each other, convert energy from light through photosynthesis. "Proteobacteria" are associated with the imbalance of microbiota of the lower reproductive tract of women. These species are associated with inflammation. "Proteobacteria" are part of a healthy placental microbiome. The group is defined in terms of ribosomal RNA sequences; the "Proteobacteria" are divided into six classes with validly published names, referred to by the Greek letters alpha through epsilon and the Acidithiobacillia and Oligoflexia.
These were regarded as subclasses of the phylum, but they are now treated as classes. These classes are monophyletic; the genus Acidithiobacillus, part of the Gammaproteobacteria until it was transferred to class Acidithiobacillia in 2013, was regarded as paraphyletic to the Betaproteobacteria according to multigenome alignment studies. In 2017, the Betaproteobacteria was subject to major revisions and the class Hydrogenophilalia was created to contain the order HydrogenophilalesProteobacterial classes with validly published names include some prominent genera: e.g.: Alphaproteobacteria: Brucella, Agrobacterium, Rickettsia, etc. Betaproteobacteria: Bordetella, Neisseria, etc. Gammaproteobacteria: Escherichia, Salmonella, Buchnera, Vibrio, etc. Deltaproteobacteria: Desulfovibrio, Bdellovibrio, etc. Epsilonproteobacteria: Helicobacter, Wolinella, etc. Oligoflexia: Oligoflexus. Acidithiobacillia: Acidithiobacillus thiooxidans, Thermithiobacillus tepidarius Hydrogenophilalia: Hydrogenophilus thermoluteolus, Tepidiphilus margaritifer Transformation, a process in which genetic material passes from bacterium to another, has been reported in at least 30 species of "Proteobacteria" distributed in the classes alpha, beta and epsilon.
The best-studied "Proteobacteria" with respect to natural genetic transformation are the medically important human pathogens Neisseria gonorrhoeae, Haemophilus influenzae and Helicobacter pylori. Natural genetic transformation is a sexual process involving DNA transfer from one bacterial cell to another through the intervening medium and the integration of the donor sequence into the recipient genome. In pathogenic "Proteobacteria", transformation appears to serve as a DNA repair process that protects the pathogen's DNA from attack by their host's phagocytic defenses that employ oxidative free radicals. Proteobacteria information from Palaeos. Proteobacteria. – J. P. Euzéby: List of Prokaryotic names with Standing in Nomenclature
A microbiologist is a scientist who studies microscopic life forms and processes. This includes study of the growth and characteristics of microscopic organisms such as bacteria, algae and some types of parasites and their vectors. Most microbiologists work in offices and/or research facilities, both in private biotechnology companies as well as in academia. Most microbiologists specialize in a given topic within microbiology such as bacteriology, virology, or immunology. Microbiologists work in some way to increase scientific knowledge, or to utilize that knowledge in a way that improves outcomes in medicine or some industry. For many microbiologists, this work includes planning and conducting experimental research projects in some kind of laboratory setting. Others may have a more administrative role, evaluating their results. Microbiologists working in the medical field, such as clinical microbiologists, may see patients or patient samples and do various tests to detect disease-causing organisms.
For microbiologists working in academia, duties include performing research in an academic laboratory, writing grant proposals to fund research, as well as some amount of teaching and designing courses. Microbiologists in industry roles may have similar duties except research is performed in industrial labs in order to develop or improve commercial products and processes. Industry jobs may include some degree of sales and marketing work, as well as regulatory compliance duties. Microbiologists working in government may have a variety of duties, including laboratory research and advising, developing and reviewing regulatory processes, overseeing grants offered to outside institutions; some microbiologists work in the field of patent law, either with national patent offices or private law practices. Here duties include navigation of intellectual property regulations. Clinical microbiologists tend to work in government or hospital laboratories where their duties include analyzing clinical specimens to detect microorganisms responsible for disease.
Some microbiologists instead work in the field of science outreach, where they develop programs and material to educate students and non-scientists and stimulate interest in the field of microbiology. Entry-level microbiology jobs require at least a bachelor's degree in microbiology or a related field; these degree programs include courses in chemistry, statistics and genetics, followed by more specialized courses in sub-fields of interest. Many of these courses have laboratory components to teach trainees basic and specialized laboratory skills. Higher-level and independent jobs require a Ph. D. as well as several years experience as a microbiologist. This includes time spent as a postdoctoral researcher wherein one leads research projects and prepares to transition to an independent career. Postdoctoral researchers are evaluated based on their record of published academic papers, as well as recommendations from their supervisors and colleagues. In certain sub-fields of microbiology, licenses or certifications are available or required in order to qualify for certain positions.
This is true for clinical microbiologists, as well as those involved in food safety and some aspects of pharmaceutical/medical device development. Microbiologists will continue to be needed to advance basic science knowledge and to contribute to development of pharmaceuticals and biotechnology products. However, job prospects vary by job and location. In the United States, the Bureau of Labor Statistics predicts that employment of microbiologists will grow 4 percent from 2014 to 2024; this represents slower growth than the average occupation, as well as slower growth than life scientists as a whole. List of prominent microbiologists Microbiology Education