Aquaculture of salmonids
The aquaculture of salmonids is the farming and harvesting of salmonids under controlled conditions for both commercial and recreational purposes. Salmonids, along with carp, tilapia are the three most important fish species in aquaculture; the most commercially farmed salmonid is the Atlantic salmon. In the U. S. Chinook salmon and rainbow trout are the most farmed salmonids for recreational and subsistence fishing through the National Fish Hatchery System. In Europe, brown trout are the most reared fish for recreational restocking. Farmed nonsalmonid fish groups include tilapia, sea bass, bream. In 2007, the aquaculture of salmonids was worth US$10.7 billion globally. Salmonid aquaculture production grew over ten-fold during the 25 years from 1982 to 2007. In 2012, the leading producers of salmonids were Norway, Chile and Canada. Much controversy exists about the ecological and health impacts of intensive salmonids aquaculture. Of particular concern are the impacts on wild salmon and other marine life.
Some of this controversy is part of a major commercial competitive fight for market share and price between Alaska commercial salmonid fishermen and the evolving salmonid aquaculture industry. The aquaculture or farming of salmonids can be contrasted with capturing wild salmonids using commercial fishing techniques. However, the concept of "wild" salmon as used by the Alaska Seafood Marketing Institute includes stock enhancement fish produced in hatcheries that have been considered ocean ranching; the percentage of the Alaska salmon harvest resulting from ocean ranching depends upon the species of salmon and location. Methods of salmonid aquaculture originated in late 18th-century fertilization trials in Europe. In the late 19th century, salmon hatcheries were used in North America. From the late 1950s, enhancement programs based on hatcheries were established in the United States, Canada and the USSR; the contemporary technique using floating sea cages originated in Norway in the late 1960s.
Salmonids are farmed in two stages and in some places maybe more. First, the salmon are raised on land in freshwater tanks. Increasing the accumulated thermal units of water during incubation reduces time to hatching; when they are 12 to 18 months old, the smolt are transferred to floating sea cages or net pens anchored in sheltered bays or fjords along a coast. This farming in a marine environment is known as mariculture. There they are fed pelleted feed for another 12 to 24 months. Norway produces 33% of the world's farmed salmonids, Chile produces 31%; the coastlines of these countries have suitable water temperatures and many areas well protected from storms. Chile is close to large forage fisheries. Scotland and Canada are significant producers. Modern salmonid, their ownership is under the control of huge agribusiness corporations, operating mechanized assembly lines on an industrial scale. In 2003, nearly half of the world’s farmed salmon was produced by just five companies. Modern commercial hatcheries for supplying salmon smolts to aquaculture net pens have been shifting to recirculating aquaculture systems s where the water is recycled within the hatchery.
This allows location of the hatchery to be independent of a significant fresh water supply and allows economical temperature control to both speed up and slow down the growth rate to match the needs of the net pens. Conventional hatchery systems operate flow-through, where spring water or other water sources flow into the hatchery; the eggs are hatched in trays and the salmon smolts are produced in raceways. The waste products from the growing salmon fry and the feed are discharged into the local river. Conventional flow-through hatcheries, for example the majority of Alaska's enhancement hatcheries, use more than 100 tonnes of water to produce a kg of smolts. An alternative method to hatching in freshwater tanks is to use spawning channels; these are artificial streams parallel to an existing stream with concrete or rip-rap sides and gravel bottoms. Water from the adjacent stream is piped into the top of the channel, sometimes via a header pond to settle out sediment. Spawning success is much better in channels than in adjacent streams due to the control of floods which in some years can wash out the natural redds.
Because of the lack of floods, spawning channels must sometimes be cleaned out to remove accumulated sediment. The same floods which destroy natural redds clean them out. Spawning channels preserve the natural selection of natural streams as no temptation exists, as in hatcheries, to use prophylactic chemicals to control diseases. However, exposing fish to wild parasites and pathogens using uncontrolled water supplies, combined with the high cost of spawning channels, makes this technology unsuitable for salmon aquaculture businesses; this type of technology is only useful for stock enhancement programs. Sea cages called sea pens or net pens, are made of mesh framed with steel or plastic, they can be square or circular, 10 to 32 m across and 10 m deep, with volumes between 1,000 and 10,000 m3. A large sea cage can contain up to 90,000 fish, they are placed side by side to form a system called a seafarm or seasite, with a floating wharf and walkways along the net boundaries. Additional nets can surround the seafarm to keep out predatory marine mammals.
Stocking densities range from 8 to 18 kg /m3 for Atlantic salmon and 5 to 10 kilograms /m3 for Chinook salmon. In contr
Potassium is a chemical element with symbol K and atomic number 19. It was first isolated from the ashes of plants, from which its name derives. In the periodic table, potassium is one of the alkali metals. All of the alkali metals have a single valence electron in the outer electron shell, removed to create an ion with a positive charge – a cation, which combines with anions to form salts. Potassium in nature occurs only in ionic salts. Elemental potassium is a soft silvery-white alkali metal that oxidizes in air and reacts vigorously with water, generating sufficient heat to ignite hydrogen emitted in the reaction, burning with a lilac-colored flame, it is found dissolved in sea water, is part of many minerals. Potassium is chemically similar to sodium, the previous element in group 1 of the periodic table, they have a similar first ionization energy, which allows for each atom to give up its sole outer electron. That they are different elements that combine with the same anions to make similar salts was suspected in 1702, was proven in 1807 using electrolysis.
Occurring potassium is composed of three isotopes, of which 40K is radioactive. Traces of 40K are found in all potassium, it is the most common radioisotope in the human body. Potassium ions are vital for the functioning of all living cells; the transfer of potassium ions across nerve cell membranes is necessary for normal nerve transmission. Fresh fruits and vegetables are good dietary sources of potassium; the body responds to the influx of dietary potassium, which raises serum potassium levels, with a shift of potassium from outside to inside cells and an increase in potassium excretion by the kidneys. Most industrial applications of potassium exploit the high solubility in water of potassium compounds, such as potassium soaps. Heavy crop production depletes the soil of potassium, this can be remedied with agricultural fertilizers containing potassium, accounting for 95% of global potassium chemical production; the English name for the element potassium comes from the word "potash", which refers to an early method of extracting various potassium salts: placing in a pot the ash of burnt wood or tree leaves, adding water and evaporating the solution.
When Humphry Davy first isolated the pure element using electrolysis in 1807, he named it potassium, which he derived from the word potash. The symbol "K" stems from kali, itself from the root word alkali, which in turn comes from Arabic: القَلْيَه al-qalyah "plant ashes". In 1797, the German chemist Martin Klaproth discovered "potash" in the minerals leucite and lepidolite, realized that "potash" was not a product of plant growth but contained a new element, which he proposed to call kali. In 1807, Humphry Davy produced the element via electrolysis: in 1809, Ludwig Wilhelm Gilbert proposed the name Kalium for Davy's "potassium". In 1814, the Swedish chemist Berzelius advocated the name kalium for potassium, with the chemical symbol "K"; the English and French speaking countries adopted Davy and Gay-Lussac/Thénard's name Potassium, while the Germanic countries adopted Gilbert/Klaproth's name Kalium. The "Gold Book" of the International Union of Physical and Applied Chemistry has designated the official chemical symbol as K.
Potassium is the second least dense metal after lithium. It is a soft solid with a low melting point, can be cut with a knife. Freshly cut potassium is silvery in appearance, but it begins to tarnish toward gray on exposure to air. In a flame test and its compounds emit a lilac color with a peak emission wavelength of 766.5 nanometers. Neutral potassium atoms have 19 electrons, one more than the stable configuration of the noble gas argon; because of this and its low first ionization energy of 418.8 kJ/mol, the potassium atom is much more to lose the last electron and acquire a positive charge than to gain one and acquire a negative charge. This process requires so little energy that potassium is oxidized by atmospheric oxygen. In contrast, the second ionization energy is high, because removal of two electrons breaks the stable noble gas electronic configuration. Potassium therefore does not form compounds with the oxidation state of higher. Potassium is an active metal that reacts violently with oxygen in water and air.
With oxygen it forms potassium peroxide, with water potassium forms potassium hydroxide. The reaction of potassium with water is dangerous because of its violent exothermic character and the production of hydrogen gas. Hydrogen reacts again with atmospheric oxygen, producing water, which reacts with the remaining potassium; this reaction requires only traces of water. Because of the sensitivity of potassium to water and air, reactions with other elements are possible only in an inert atmosphere such as argon gas using air-free techniques. Potassium does not react with most hydrocarbons such as mineral kerosene, it dissolves in liquid ammonia, up to 480 g per 1000 g of ammonia at 0 °C. Depending on the concentration, the ammonia solutions are blue to yellow, their electrical conductivity is similar to that of liquid metals. In a pure solution, potassium reacts with ammonia to form KNH2, but this reaction is accelerated by minute amounts of transition metal s
Astaxanthin is a keto-carotenoid. It belongs to a larger class of chemical compounds known as terpenes built from five carbon precursors, isopentenyl diphosphate, dimethylallyl diphosphate. Astaxanthin is classified as a xanthophyll, but employed to describe carotenoid compounds that have oxygen-containing components, hydroxyl or ketone, such as zeaxanthin and canthaxanthin. Indeed, astaxanthin is a metabolite of zeaxanthin and/or canthaxanthin, containing both hydroxyl and ketone functional groups. Like many carotenoids, astaxanthin is a lipid-soluble pigment, its red-orange colour is due to the extended chain of conjugated double bonds at the centre of the compound. This chain of conjugated double bonds is responsible for the antioxidant function of astaxanthin as it results in a region of decentralized electrons that can be donated to reduce a reactive oxidizing molecule. Astaxanthin is a blood-red pigment and originates in the rainwater microalgae and the yeast fungus called Xanthophyllomyces dendrorhous.
The algae undergoes a stressing via one or a combination of conditions ranging from the lack of nutrients, increased salinity, excessive sunshine to create Astaxanthin. The species that consume this stressed freshwater microalgae—salmon, red trout, red sea bream, crustaceans -- reflect the pigmentation of the red-orange hues in their appearances; the structure of astaxanthin by synthesis was described in 1975. Astaxanthin is not converted to vitamin A in the human body so it is nontoxic if given orally. Astaxanthin can be used as a dietary supplement intended for human and aquaculture consumption; the industrial production of astaxanthin comes from plant - or synthetic sources. The U. S. Food and Drug Administration has approved astaxanthin as a food coloring for specific uses in animal and fish foods; the European Commission considers it food dye and it is given the E number E161j. Astaxanthin from algae and bacterial sources, is recognized as safe by the FDA; as a food color additive astaxanthin and astaxanthin dimethyldisuccinate are restricted for use in Salmonid fish feed only.
Astaxanthin is present in most red-coloured aquatic organisms. The content varies from species to species, but from individual to individual as it is dependent on diet and living conditions. Astaxanthin, other chemically related asta-carotenoids, has been found in a number of lichen species of the arctic zone; the primary natural sources for industrial production of astaxanthin comprise the following: Euphausia pacifica Euphausia superba Haematococcus pluvialis Pandalus borealis Xanthophyllomyces dendrorhous Phaffia rhodozyma Astaxanthin concentrations in nature are approximately: Algae are the primary natural source of astaxanthin in the aquatic food chain. The microalgae Haematococcus pluvialis seems to accumulate the highest levels of astaxanthin in nature and is the primary industrial source for natural astaxanthin production where more than 40 g of astaxanthin can be obtained from one kg of dry biomass. Haematococcus pluvialis has the productional advantage of the population doubling every week, which means scaling up is not an issue.
The microalgae are grown in two phases. First, in the green phase, the cells are given an abundance of nutrients to promote proliferation of the cells. In the subsequent red phase, the cells are deprived of nutrients and subjected to intense sunlight to induce encystment, during which the cells produce high levels of astaxanthin as a protective mechanism against the environmental stress; the cells, with their high concentrations of astaxanthin, are harvested. Phaffia yeast Xanthophyllomyces dendrorhous exhibits 100% free, non-esterified astaxanthin, considered advantageous because it is absorbable and need not be hydrolysed in the digestive tract of the fish. In contrast to synthetic and bacteria sources of astaxanthin, yeast sources of astaxanthin consist of the -form, an important astaxanthin source in nature; the geometrical isomer, all-E, is higher in yeast sources of astaxanthin, as compared to synthetic sources. In shellfish, astaxanthin is exclusively concentrated in the shells, with only low amounts in the flesh itself, most of it only becomes visible during cooking as the pigment separates from the denatured proteins that otherwise bind it.
Astaxanthin is extracted from shrimp processing waste. 12,000 pounds of wet shrimp shells can yield a 6–8 gallon astaxanthin/triglyceride oil mixture. Nearly all commercially available astaxanthin for aquaculture is produced synthetically, with an annual turnover of over $200 million and a selling price of $5000–6000 per kilo as of July 2012; the market grew to over $500 million by 2016 and is expected to continue to grow with the aquaculture industry. An efficient synthesis from isophorone, cis-3-methyl-2-penten-4-yn-1-ol and a symmetrical C10-dialdehyde has been discovered and is used in industrial production, it combines these chemicals together with an ethynylation and a Wittig reaction. Two equivalents of the proper ylide combined with the proper dialdehyde in a solvent of methanol, ethanol, or a mixture of the two, yields astaxanthin in up to 88% yields; the cost of astaxanthin production, high mar
A polychlorinated biphenyl is an organic chlorine compound with the formula C12H10−xClx. Polychlorinated biphenyls were once deployed as dielectric and coolant fluids in electrical apparatus, carbonless copy paper and in heat transfer fluids; because of their longevity, PCBs are still in use though their manufacture has declined drastically since the 1960s, when a host of problems were identified. With the discovery of PCBs' environmental toxicity, classification as persistent organic pollutants, their production was banned by United States federal law in 1978, by the Stockholm Convention on Persistent Organic Pollutants in 2001; the International Agency for Research on Cancer, rendered PCBs as definite carcinogens in humans. According to the U. S. Environmental Protection Agency, PCBs are probable human carcinogens. Many rivers and buildings, including schools and other sites, are contaminated with PCBs and there has been contamination of food supplies with the substances; some PCBs share a structural similarity and toxic mode of action with dioxins.
Other toxic effects such as endocrine disruption and neurotoxicity are known. The maximum allowable contaminant level in drinking water in the United States is set at zero, but because of the limitations of water treatment technologies, a level of 0.5 parts per billion is the de facto level. The bromine analogues of PCBs are polybrominated biphenyls, which have analogous applications and environmental concerns; the compounds are pale-yellow viscous liquids. They are hydrophobic, with low water solubilities: 0.0027–0.42 ng/L for Aroclors, but they have high solubilities in most organic solvents and fats. They have low vapor pressures at room temperature, they have dielectric constants of 2.5–2.7 high thermal conductivity, high flash points. The density varies from 1.182 to 1.566 g/cm3. Other physical and chemical properties vary across the class; as the degree of chlorination increases, melting point and lipophilicity increase, vapour pressure and water solubility decrease. PCBs do not break down or degrade, which made them attractive for industries.
PCB mixtures are resistant to acids, oxidation and temperature change. They can generate toxic dibenzodioxins and dibenzofurans through partial oxidation. Intentional degradation as a treatment of unwanted PCBs requires high heat or catalysis. PCBs penetrate skin, PVC, latex. PCB-resistant materials include Viton, polyvinyl acetate, polytetrafluoroethylene, butyl rubber, nitrile rubber, Neoprene. PCBs are derived from biphenyl, which has the formula C12H10, sometimes written 2. In PCBs, some of the hydrogen atoms in biphenyl are replaced by chlorine atoms. There are 209 different chemical compounds in which one to ten chlorine atoms can replace hydrogen atoms. PCBs are used as mixtures of compounds and are given the single identifying CAS number 1336-36-3. About 130 different individual PCBs are found in commercial PCB products. Toxic effects vary depending on the specific PCB. In terms of their structure and toxicity, PCBs fall into two distinct categories, referred to as coplanar or non-ortho-substituted arene substitution patterns and noncoplanar or ortho-substituted congeners.
Coplanar or non-ortho The coplanar group members have a rigid structure, with their two phenyl rings in the same plane. It renders their structure similar to polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans, allows them to act like PCDDs, as an agonist of the aryl hydrocarbon receptor in organisms, they are considered as contributors to overall dioxin toxicity, the term dioxins and dioxin-like compounds is used interchangeably when the environmental and toxic impact of these compounds is considered. Noncoplanar Noncoplanar PCBs, with chlorine atoms at the ortho positions can cause neurotoxic and immunotoxic effects, but only at concentrations much higher than those associated with dioxins, they do not activate the AhR, are not considered part of the dioxin group. Because of their lower toxicity, they are of less concern to regulatory bodies. Di-ortho-substituted, non-coplanar PCBs interfere with intracellular signal transduction dependent on calcium which may lead to neurotoxicity.
Ortho-PCBs can disrupt thyroid hormone transport by binding to transthyretin. Commercial PCB mixtures were marketed under the following names: The only North American producer, Monsanto Company, marketed PCBs under the trade name Aroclor from 1930 to 1977; these were sold under trade names followed by a four-digit number. In general, the first two digits refer to the product series. Thus, Aroclor 1260 contains 60 % chlorine by mass, it is a myth. The 1100 series was a crude PCB material, distilled to create the 1200 series PCB product; the exception to the naming system is Aroclor 1016, produced by distilling 1242 to remove the chlorinated congeners to make a more biodegradable product. "1016" was given to this product during Monsanto's research stage for tracking purposes but the name stuck after it was commercialized. Different Aroclors were used for different applications. In electrical equipment manufacturing in the US, Aroclor 1260 and Aroclor 1254 were the main mixtures used before 1950.
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, providing structure to cells and organisms, transporting molecules from one location to another. Proteins differ from one another in their sequence of amino acids, dictated by the nucleotide sequence of their genes, which results in protein folding into a specific three-dimensional structure that determines its activity. 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 considered to be proteins and are called peptides, or sometimes oligopeptides; the individual amino acid residues are bonded together by peptide bonds and adjacent amino acid residues. The sequence of amino acid residues in a protein is defined by the sequence of a gene, encoded in the genetic code.
In general, the genetic code specifies 20 standard amino acids. Shortly after or during synthesis, the residues in a protein are chemically modified by post-translational modification, which alters the physical and chemical properties, stability and the function of the proteins. Sometimes proteins have non-peptide groups attached, which can be called prosthetic groups or cofactors. Proteins can work together to achieve a particular function, they associate to form stable protein complexes. Once formed, proteins only exist for a certain period and are degraded and recycled by the cell's machinery through the process of protein turnover. A protein's lifespan covers a wide range, they can exist for years with an average lifespan of 1 -- 2 days in mammalian cells. Abnormal or misfolded proteins are degraded more either 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 and participate in every process within cells.
Many proteins are enzymes that are vital to metabolism. Proteins have structural or mechanical functions, such as actin and myosin in muscle and the proteins in the cytoskeleton, which form a system of scaffolding that maintains cell shape. Other proteins are important in cell signaling, immune responses, cell adhesion, 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. Proteins may be purified from other cellular components using a variety of techniques such as ultracentrifugation, precipitation and chromatography. Methods used to study protein structure and function include immunohistochemistry, site-directed mutagenesis, X-ray crystallography, nuclear magnetic resonance and mass spectrometry. 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, a variable side chain are bonded.
Only proline differs from this basic structure as it contains an unusual ring to the N-end amine group, which forces the CO–NH amide moiety into a fixed conformation. The side chains of the standard amino acids, detailed in the list of standard amino acids, have a great variety of chemical structures and properties; the amino acids in a polypeptide chain are linked by peptide bonds. Once linked in the protein chain, an individual amino acid is called a residue, the linked series of carbon and oxygen atoms are known as the main chain or protein backbone; the peptide bond has two resonance forms that contribute some double-bond character and inhibit rotation around its axis, so that the alpha carbons are coplanar. The other two dihedral angles in the peptide bond determine the local shape assumed by the protein backbone; the end with a free amino group is known as the N-terminus or amino terminus, whereas the end of the protein with a free carboxyl group is known as the C-terminus or carboxy terminus.
The words protein and peptide are a little ambiguous and can overlap in meaning. Protein is used to refer to the complete biological molecule in a stable conformation, whereas peptide is reserved for a short amino acid oligomers lacking a stable three-dimensional structure. However, the boundary between the two is not well defined and lies near 20–30 residues. Polypeptide can refer to any single linear chain of amino acids regardless of length, but implies an absence of a defined conformation. Proteins can interact with many types of molecules, including with other proteins, with lipids, with carboyhydrates, with DNA, it has been estimated. Smaller bacteria, such as Mycoplasma or spirochetes contain fewer molecules, on the order of 50,000 to 1 million. By contrast, eukaryotic cells are larger and thus contain much more pro
Omega-6 fatty acid
Omega-6 fatty acids are a family of polyunsaturated fatty acids that have in common a final carbon-carbon double bond in the n-6 position, that is, the sixth bond, counting from the methyl end. Members of the family can have anti-inflammatory effects; the biological effects of the omega-6 fatty acids are produced during and after physical activity for the purpose of promoting growth and during the inflammatory cascade to halt cell damage and promote cell repair by their conversion to omega-6 eicosanoids that bind to diverse receptors found in every tissue of the body. Linoleic acid, the shortest-chained omega-6 fatty acid, is one of many essential fatty acids and is categorized as an essential fatty acid because the human body cannot synthesize it. Mammalian cells lack the enzyme omega-3 desaturase and therefore cannot convert omega-6 fatty acids to omega-3 fatty acids. Related omega-3 and omega-6 fatty acids act as competing substrates for the same enzymes; this outlines the importance of the proportion of omega-3 to omega-6 fatty acids in a diet.
Omega-6 fatty acids are precursors to endocannabinoids and specific eicosanoids. Medical research on humans found a correlation between the high intake of omega-6 fatty acids from vegetable oils and disease in humans. However, biochemistry research has concluded that air pollution, heavy metals, passive smoking, lipopolysaccharides, lipid peroxidation products and other exogenous toxins initiate the inflammatory response in the cells which leads to the expression of the COX-2 enzyme and subsequently to the temporary production of inflammatory promoting prostaglandins from arachidonic acid for the purpose of alerting the immune system of the cell damage and to the production of anti-inflammatory molecules during the resolution phase of inflammation, after the cell damage has been repaired; the conversion of cell membrane arachidonic acid to omega-6 prostaglandin and omega-6 leukotriene eicosanoids during the inflammatory cascade provides many targets for pharmaceutical drugs to impede the inflammatory process in atherosclerosis, arthritis, vascular disease, immune-inflammatory processes, tumor proliferation.
Competitive interactions with the omega-3 fatty acids affect the relative storage, mobilization and action of the omega-3 and omega-6 eicosanoid precursors. Some medical research suggests that excessive levels of omega-6 fatty acids from seed oils relative to certain omega-3 fatty acids may increase the probability of a number of diseases.. However, consumption of non-rancid nuts, which are high in omega 6, is associated with a lower risk for some diseases, such as cardiovascular diseases including coronary heart disease, stroke, heart attacks, lower rates of premature death. Modern Western diets have ratios of omega-6 to omega-3 in excess of 10, some as high as 30. Humans are thought to have evolved with a diet of a 1-to-1 ratio of omega-6 to omega-3 and the optimal ratio is thought to be 4 or lower, although some sources suggest ratios as low as 1. A ratio of 2–3 omega-6 to omega-3 helped reduce inflammation in patients with rheumatoid arthritis. A ratio of 5 had a beneficial effect on patients with asthma but a ratio of 10 had a negative effect.
A ratio of 2.5 reduced rectal cell proliferation in patients with colorectal cancer, whereas a ratio of 4 had no effect. Excess omega-6 fatty acids from vegetable oils interfere with the health benefits of omega-3 fats, in part because they compete for the same rate-limiting enzymes. A high proportion of omega-6 to omega-3 fat in the diet shifts the physiological state in the tissues toward the pathogenesis of many diseases: prothrombotic and proconstrictive. Chronic excessive production of omega-6 eicosanoids is correlated with arthritis and cancer. Many of the medications used to treat and manage these conditions work by blocking the effects of the COX-2 enzyme. Many steps in formation and action of omega-6 prostaglandins from omega-6 arachidonic acid proceed more vigorously than the corresponding competitive steps in formation and action of omega-3 hormones from omega-3 eicosapentaenoic acid; the COX-1 and COX-2 inhibitor medications, used to treat inflammation and pain, work by preventing the COX enzymes from turning arachidonic acid into inflammatory compounds.
The LOX inhibitor medications used to treat asthma work by preventing the LOX enzyme from converting arachidonic acid into the leukotrienes. Many of the anti-mania medications used to treat bipolar disorder work by targeting the arachidonic acid cascade in the brain. A high consumption of oxidized polyunsaturated fatty acids, which are found in most types of vegetable oil, may increase the likelihood that postmenopausal women will develop breast cancer. Similar effect was observed on prostate cancer. Another "analysis suggested an inverse association between total polyunsaturated fatty acids and breast cancer risk, but individual polyunsaturated fatty acids behaved differently. A 20:2 derivative of linoleic acid was inversely associated with the risk of breast cancer". Industry-sponsored studies have suggested that omega-6 fatty acids should be consumed in a 1:1 ratio to omega-3, though it has been observed that the diet of many individuals today is at a ratio of about 16:1 from vegetable oils.
Omega-6 and omega-3 are e
Édouard Manet was a French modernist painter. He was one of the first 19th-century artists to paint modern life, a pivotal figure in the transition from Realism to Impressionism. Born into an upper-class household with strong political connections, Manet rejected the future envisioned for him, became engrossed in the world of painting, his early masterworks, The Luncheon on the Grass and Olympia, both 1863, caused great controversy and served as rallying points for the young painters who would create Impressionism. Today, these are considered watershed paintings; the last 20 years of Manet's life saw him form bonds with other great artists of the time, develop his own style that would be heralded as innovative and serve as a major influence for future painters. Édouard Manet was born in Paris on 23 January 1832, in the ancestral hôtel particulier on the rue des Petits Augustins to an affluent and well-connected family. His mother, Eugénie-Desirée Fournier, was the daughter of a diplomat and goddaughter of the Swedish crown prince Charles Bernadotte, from whom the Swedish monarchs are descended.
His father, Auguste Manet, was a French judge. His uncle, Edmond Fournier, took young Manet to the Louvre. In 1841 he enrolled at the Collège Rollin. In 1845, at the advice of his uncle, Manet enrolled in a special course of drawing where he met Antonin Proust, future Minister of Fine Arts and subsequent lifelong friend. At his father's suggestion, in 1848 he sailed on a training vessel to Rio de Janeiro. After he twice failed the examination to join the Navy, his father relented to his wishes to pursue an art education. From 1850 to 1856, Manet studied under the academic painter Thomas Couture. In his spare time, Manet copied the Old Masters in the Louvre. From 1853 to 1856, Manet visited Germany and the Netherlands, during which time he was influenced by the Dutch painter Frans Hals, the Spanish artists Diego Velázquez and Francisco José de Goya. In 1856, Manet opened a studio, his style in this period was characterized by loose brush strokes, simplification of details and the suppression of transitional tones.
Adopting the current style of realism initiated by Gustave Courbet, he painted The Absinthe Drinker and other contemporary subjects such as beggars, Gypsies, people in cafés, bullfights. After his early career, he painted religious, mythological, or historical subjects. Manet had two canvases accepted at the Salon in 1861. A portrait of his mother and father, who at the time was paralysed and robbed of speech by a stroke, was ill-received by critics; the other, The Spanish Singer, was admired by Theophile Gautier, placed in a more conspicuous location as a result of its popularity with Salon-goers. Manet's work, which appeared "slightly slapdash" when compared with the meticulous style of so many other Salon paintings, intrigued some young artists; the Spanish Singer, painted in a "strange new fashion caused many painters' eyes to open and their jaws to drop." Music in the Tuileries is an early example of Manet's painterly style. Inspired by Hals and Velázquez, it is a harbinger of his lifelong interest in the subject of leisure.
While the picture was regarded as unfinished by some, the suggested atmosphere imparts a sense of what the Tuileries gardens were like at the time. Here, Manet has depicted his friends, artists and musicians who take part, he has included a self-portrait among the subjects. A major early work is The Luncheon on the Grass Le Bain; the Paris Salon rejected it for exhibition in 1863, but Manet agreed to exhibit it at the Salon des Refusés, a parallel exhibition to the official Salon, as an alternative exhibition in the Palais des Champs-Elysée. The Salon des Refusés was initiated by Emperor Napoleon III as a solution to a problematic situation which came about as the Selection Committee of the Salon that year rejected 2,783 paintings of the ca. 5000. Each painter could decide whether to take the opportunity to exhibit at the Salon des Refusés, less than 500 of the rejected painters chose to do so. Manet employed model Victorine Meurent, his wife Suzanne, future brother-in-law Ferdinand Leenhoff, one of his brothers to pose.
Meurent posed for several more of Manet's important paintings including Olympia. The painting's juxtaposition of dressed men and a nude woman was controversial, as was its abbreviated, sketch-like handling, an innovation that distinguished Manet from Courbet. At the same time, Manet's composition reveals his study of the old masters, as the disposition of the main figures is derived from Marcantonio Raimondi's engraving of the Judgement of Paris based on a drawing by Raphael. Two additional works cited by scholars as important precedents for Le déjeuner sur l'herbe are Pastoral Concert and The Tempest, both of which are attributed variously to Italian Renaissance masters Giorgione or Titian; the Tempest is an enigmatic painting featuring a dressed man and a nude woman in a rural setting. The man is standing to the left and gazing to the side at the woman, seated and breastfeeding a baby. In Pastoral Concert, two clothed men