|
Polyunsaturated Aldehyde
Polyunsaturated aldehydes (PUAs) are a group of allelopathic chemicals typically associated with diatom-copepod predator-prey interactions.Miller, Charles B. Biological Oceanography. Malden, MA: Blackwell Pub., 2004. Print. These compounds are classified by an aldehyde group covalently bound to long carbon chains containing two or more carbon-carbon double bonds. Examples include isomers of heptadienal, octadienal, octatrienal, and decatrienal. Production by diatoms Polyunsaturated aldehydes are oxylipins that are formed from lipids (specifically the fatty acid portion of lipids) when diatoms are exposed to environmental stresses. Stresses can include nutrient limitations, grazing by predators, and wounding. In particular, damage to diatom cells as a result of grazing by zooplankton invokes a chemical defense mechanism that produces PUA’s as secondary metabolites from fatty acids. The production mechanism is as follows: # Grazing by predators results in diatom cell ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allelopathic
Allelopathy is a biological phenomenon by which an organism produces one or more biochemicals that influence the germination, growth, survival, and reproduction of other organisms. These biochemicals are known as allelochemicals and can have beneficial (positive allelopathy) or detrimental (negative allelopathy) effects on the target organisms and the community. Allelopathy is often used narrowly to describe chemically-mediated competition between plants; however, it is sometimes defined more broadly as chemically-mediated competition between any type of organisms. Allelochemicals are a subset of secondary metabolites, which are not directly required for metabolism (i.e. growth, development and reproduction) of the allelopathic organism. Allelopathic interactions are an important factor in determining species distribution and abundance within plant communities, and are also thought to be important in the success of many invasive plants. For specific examples, see black walnut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zooplankton
Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by currents in the ocean, or by currents in seas, lakes or rivers. Zooplankton can be contrasted with phytoplankton, which are the plant component of the plankton community ("phyto" comes from the Greek word for ''plant''). Zooplankton are heterotrophic (other-feeding), whereas phytoplankton are autotrophic (self-feeding). This means zooplankton cannot manufacture their own food but must eat other plants or animals instead — in particular they eat phytoplankton. Zooplankton are generally larger than phytoplankton, most are microscopic, but some (such as jellyfish) are macroscopic and can be seen with the naked eye. Many protozoans (single-celled protists that prey on other microscopic life) are zooplankton, including zooflagellat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Skeletonema Marinoi
''Skeletonema marinoi'' is a diatom A diatom (Neo-Latin ''diatoma''), "a cutting through, a severance", from el, διάτομος, diátomos, "cut in half, divided equally" from el, διατέμνω, diatémno, "to cut in twain". is any member of a large group comprising sev .... Together with '' S. dohrnii'', this species has flattened extremities of the processes of the fultoportulae, which interlock with those of succeeding valves without forming knuckles. See also * Imidazolium * Pyridinium * Chlorella vulgaris References Further reading * * * External links *AlgaeBase Protists described in 2005 Thalassiosirales {{diatom-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phaeocystis Pouchetii
''Phaeocystis'' is a genus of algae belonging to the Prymnesiophyte class and to the larger division of Haptophyta. It is a widespread marine phytoplankton and can function at a wide range of temperatures ( eurythermal) and salinities (euryhaline). Members of this genus live in the open ocean, as well as in sea ice. It has a polymorphic life cycle, ranging from free-living cells to large colonies. The ability to form a floating colony is one of the unique attributes of ''Phaeocystis'' – hundreds of cells are embedded in a polysaccharide gel matrix, which can increase massively in size during blooms. The largest ''Phaeocystis'' blooms form in the polar seas: ''P. pouchetii'' in the north and ''P. antarctica'' in the south. This intense ''Phaeocystis'' productivity generally persists for about a three-month period, spanning most of the summer in the Southern Hemisphere. ''Phaeocystis''-abundant ecosystems are generally associated with commercially important stocks of crust ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Skeletonema Costatum
''Skeletonema costatum'' is a cosmopolitan centric diatom that belongs to the genus '' Skeletonema''. It was first described by R. K. Greville, who originally named it ''Melosira costata,'' in 1866. It was later renamed by Cleve in 1873 and was more narrowly defined by Zingone et al. and Sarno et al. '' Skeletonema'' ''costatum'' is the most well known species of the genus ''Skeletonema'' and is often one of the dominant species responsible for red tide events. The diatom ''S. costatum'' is known for its carbon acquisition mechanisms, and it has been used in the production of biofuel and as a feed for aquaculture. The organism is appealing for commercial use due to its high photosynthetic efficiency, high tolerance to pH, temperature, and salinity changes, high lipid and fatty acid content, and rapid growth rate. Structure and morphology Cells belonging to ''S. costatum'' are single-celled but exist as long chains of about 6 to 24 cells but can be up to 60 cells in length. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thalassiosira Rotula
''Thalassiosira'' is a genus of centric diatoms, comprising over 100 marine and freshwater species. It is a diverse group of photosynthetic eukaryotes that make up a vital part of marine and freshwater ecosystems, in which they are key primary producers and essential for carbon cycling Dreux Chappell, P., Whitney, L. A. P., Haddock, T. L., Menden-Deuer, S., Roy, E. G., Wells, M. L., & Jenkins, B. D. (2013). Thalassiosira spp. community composition shifts in response to chemical and physical forcing in the northeast Pacific Ocean. Frontiers in Microbiology, 4(SEP), 273. https://doi.org/10.3389/fmicb.2013.00273 ''Thalassiosira'' is a diverse genus, however one species within the genus, ''T. pseudonana'', has gained particular significance as the first marine phytoplankton to have its genome sequenced. ''T. pseudonana'' has since become a key model organism for studying diatom physiology. The ''T. pseudonana'' genome revealed novel genes for intracellular trafficking and metabolism ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lipoxygenase
Lipoxygenases () are a family of (non-heme) iron-containing enzymes most of which catalyze the dioxygenation of polyunsaturated fatty acids in lipids containing a cis,cis-1,4- pentadiene into cell signaling agents that serve diverse roles as autocrine signals that regulate the function of their parent cells, paracrine signals that regulate the function of nearby cells, and endocrine signals that regulate the function of distant cells. The lipoxygenases are related to each other based upon their similar genetic structure and dioxygenation activity. However, one lipoxygenase, ALOXE3, while having a lipoxygenase genetic structure, possesses relatively little dioxygenation activity; rather its primary activity appears to be as an isomerase that catalyzes the conversion of hydroperoxy unsaturated fatty acids to their 1,5-epoxide, hydroxyl derivatives. Lipoxygenases are found in eukaryotes (plants, fungi, animals, protists); while the third domain of terrestrial life, the archaea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catalyze
Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quickly, very small amounts of catalyst often suffice; mixing, surface area, and temperature are important factors in reaction rate. Catalysts generally react with one or more reactants to form intermediates that subsequently give the final reaction product, in the process of regenerating the catalyst. Catalysis may be classified as either homogeneous, whose components are dispersed in the same phase (usually gaseous or liquid) as the reactant, or heterogeneous, whose components are not in the same phase. Enzymes and other biocatalysts are often considered as a third category. Catalysis is ubiquitous in chemical industry of all kinds. Estimates are that 90% of all commercially produced chemical products involve catalysts at some stag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phospholipids
Phospholipids, are a class of lipids whose molecule has a hydrophilic "head" containing a phosphate group and two hydrophobic "tails" derived from fatty acids, joined by an alcohol residue (usually a glycerol molecule). Marine phospholipids typically have omega-3 fatty acids EPA and DHA integrated as part of the phospholipid molecule. The phosphate group can be modified with simple organic molecules such as choline, ethanolamine or serine. Phospholipids are a key component of all cell membranes. They can form lipid bilayers because of their amphiphilic characteristic. In eukaryotes, cell membranes also contain another class of lipid, sterol, interspersed among the phospholipids. The combination provides fluidity in two dimensions combined with mechanical strength against rupture. Purified phospholipids are produced commercially and have found applications in nanotechnology and materials science. The first phospholipid identified in 1847 as such in biological tissues was leci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lipases
Lipase ( ) is a family of enzymes that catalyzes the hydrolysis of fats. Some lipases display broad substrate scope including esters of cholesterol, phospholipids, and of lipid-soluble vitamins and sphingomyelinases; however, these are usually treated separately from "conventional" lipases. Unlike esterases, which function in water, lipases "are activated only when adsorbed to an oil–water interface". Lipases perform essential roles in digestion, transport and processing of dietary lipids in most, if not all, organisms. Structure and catalytic mechanism Classically, lipases catalyse the hydrolysis of triglycerides: :triglyceride + H2O → fatty acid + diacylglycerol :diacylglycerol + H2O → fatty acid + monacylglycerol :monacylglycerol + H2O → fatty acid + glycerol Lipases are serine hydrolases, i.e. they function by transesterification generating an acyl serine intermediate. Most lipases act at a specific position on the glycerol backbone of a lipid s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzymes
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. Almost all metabolic processes in the cell need enzyme catalysis in order to occur at rates fast enough to sustain life. Metabolic pathways depend upon enzymes to catalyze individual steps. The study of enzymes is called ''enzymology'' and the field of pseudoenzyme analysis recognizes that during evolution, some enzymes have lost the ability to carry out biological catalysis, which is often reflected in their amino acid sequences and unusual 'pseudocatalytic' properties. Enzymes are known to catalyze more than 5,000 biochemical reaction types. Other biocatalysts are catalytic RNA molecules, called ribozymes. Enzymes' specificity comes from their unique three-dimensional structures. Like all catalysts, enzymes increase the reacti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
