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Palytoxin
Palytoxin, PTX or PLTX is an intense vasoconstrictor, and is considered to be one of the most poisonous non- protein substances known, second only to maitotoxin in terms of toxicity in mice. Palytoxin is a polyhydroxylated and partially unsaturated compound (8 double bonds) with a long carbon chain. It has water-soluble and fat-soluble parts, 40 hydroxy groups and 64 chiral centers. Due to chirality and possible double bond ''cis-trans'' isomerism, it has over 1021 alternative stereoisomers. It is thermostable, and treatment with boiling water does not remove its toxicity. It remains stable in aqueous solutions for prolonged periods but rapidly decomposes and loses its toxicity in acidic or alkaline solutions. It has multiple analogues with a similar structure like ostreocin-D, mascarenotoxin-A and -B. Palytoxin occurs at least in tropics and subtropics where it is made by '' Palythoa'' corals and '' Ostreopsis'' dinoflagellates, or possibly by bacteria occurring in these or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palythoa
''Palythoa'' is a genus of anthozoans in the order Zoantharia.Reimer, J. (2018). Palythoa Lamouroux, 1816. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=205785 on 2018-08-27 Description The polyps of ''Palythoa'' are partially embedded in an encrusting mat of tissue (coenenchyme) covering the substrate on which the colony grows. The individual polyps have flattened oral discs surrounded by a fringe of tentacles. The tentacles' shape and size can vary considerably between species, and even between colonies of the same species. Their colors are also highly variable, with relatively dull shades like cream, coffee, white, brown, or yellow, being the most common. Fluorescent colored colonies also exist, but these are more rare. Palytoxin Palytoxin is a highly toxic fatty alcohol produced by many species of ''Palythoa'', and is also found in other corals and certain marine invertebrates. The substance was first isolated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ostreopsis
''Ostreopsis'' is a genus of free-living dinoflagellates found in marine environments. Some species are benthic; the planktonic species in the genus are known for the toxic algal blooms that they sometimes cause, threatening human and animal health. Taxonomy The taxonomy of this genus is problematic. When in 1901, Schmidt first created the genus ''Ostreopsis'', he described the type species '' O. siamensis'' from the phytoplankton in the waters of the Gulf of Thailand. However, there were anomalies in the original drawing made by Schmidt, and ''O. siamensis'' was redescribed by Fukuyo in 1981; at the same time, Fukuyo introduced two new species, '' O. lenticularis'' and '' O. ovata''. Distribution and habitat ''Ostreopsis'' spp. have been found in many marine locations around the world. Despite ''O. siamensis'' having been found in the plankton, other species are generally found in benthic habitats. They are most noticeable in temperate seas when th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maitotoxin
Maitotoxin (or MTX) is an extremely powerful biotoxin produced by ''Gambierdiscus toxicus'', a dinoflagellate species. Maitotoxin has been shown to be more than one hundred thousand times more potent than VX nerve agent. Maitotoxin is so potent that it has been demonstrated that an intraperitoneal injection of 130 ng/kg was lethal in mice. Maitotoxin was named from the ciguateric fish '' Ctenochaetus striatus''—called "maito" in Tahiti—from which maitotoxin was isolated for the first time. It was later shown that maitotoxin is actually produced by the dinoflagellate ''Gambierdiscus toxicus''. Mechanism of toxicity Maitotoxin activates extracellular calcium channels, leading to an increase in levels of cytosolic Ca2+ ions. The exact molecular target of maitotoxin is unknown, but it has been suggested that maitotoxin binds to the plasma membrane Ca2+ ATPase (PMCA) and turns it into an ion channel, similar to how palytoxin turns the Na+/K+-ATPase into an ion chann ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water
Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a solvent). It is vital for all known forms of life, despite not providing food energy, food, energy or organic micronutrients. Its chemical formula, H2O, indicates that each of its molecules contains one oxygen and two hydrogen atoms, connected by covalent bonds. The hydrogen atoms are attached to the oxygen atom at an angle of 104.45°. "Water" is also the name of the liquid state of H2O at standard temperature and pressure. A number of natural states of water exist. It forms precipitation in the form of rain and aerosols in the form of fog. Clouds consist of suspended droplets of water and ice, its solid state. When finely divided, crystalline ice may precipitate in the form of snow. The gaseous state of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Base (chemistry)
In chemistry, there are three definitions in common use of the word base, known as Arrhenius bases, Brønsted bases, and Lewis bases. All definitions agree that bases are substances that react with acids, as originally proposed by G.-F. Rouelle in the mid-18th century. In 1884, Svante Arrhenius proposed that a base is a substance which dissociates in aqueous solution to form Hydroxide ions OH−. These ions can react with hydrogen ions (H+ according to Arrhenius) from the dissociation of acids to form water in an acid–base reaction. A base was therefore a metal hydroxide such as NaOH or Ca(OH)2. Such aqueous hydroxide solutions were also described by certain characteristic properties. They are slippery to the touch, can taste bitter and change the color of pH indicators (e.g., turn red litmus paper blue). In water, by altering the autoionization equilibrium, bases yield solutions in which the hydrogen ion activity is lower than it is in pure water, i.e., the wate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Starfish
Starfish or sea stars are star-shaped echinoderms belonging to the class Asteroidea (). Common usage frequently finds these names being also applied to ophiuroids, which are correctly referred to as brittle stars or basket stars. Starfish are also known as asteroids due to being in the class Asteroidea. About 1,900 species of starfish live on the seabed in all the world's oceans, from warm, tropical zones to frigid, polar regions. They are found from the intertidal zone down to abyssal depths, at below the surface. Starfish are marine invertebrates. They typically have a central disc and usually five arms, though some species have a larger number of arms. The aboral or upper surface may be smooth, granular or spiny, and is covered with overlapping plates. Many species are brightly coloured in various shades of red or orange, while others are blue, grey or brown. Starfish have tube feet operated by a hydraulic system and a mouth at the centre of the oral or lower surfac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mussel
Mussel () is the common name used for members of several families of bivalve molluscs, from saltwater and freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other edible clams, which are often more or less rounded or oval. The word "mussel" is frequently used to mean the bivalves of the marine family Mytilidae, most of which live on exposed shores in the intertidal zone, attached by means of their strong byssal threads ("beard") to a firm substrate. A few species (in the genus '' Bathymodiolus'') have colonised hydrothermal vents associated with deep ocean ridges. In most marine mussels the shell is longer than it is wide, being wedge-shaped or asymmetrical. The external colour of the shell is often dark blue, blackish, or brown, while the interior is silvery and somewhat nacreous. The common name "mussel" is also used for many freshwater bivalves, including the freshwater pearl mussels. Freshwater mussel speci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sponge
Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through them, consisting of jelly-like mesohyl sandwiched between two thin layers of cells. Sponges have unspecialized cells that can transform into other types and that often migrate between the main cell layers and the mesohyl in the process. Sponges do not have nervous, digestive or circulatory systems. Instead, most rely on maintaining a constant water flow through their bodies to obtain food and oxygen and to remove wastes. Sponges were first to branch off the evolutionary tree from the last common ancestor of all animals, making them the sister group of all other animals. Etymology The term ''sponge'' derives from the Ancient Greek word ( 'sponge'). Overview Sponges are similar to other animals in that they are multicellular, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biomagnification
Biomagnification, also known as bioamplification or biological magnification, is any concentration of a toxin, such as pesticides, in the tissues of tolerant organisms at successively higher levels in a food chain. This increase can occur as a result of: * Persistence – where the substance cannot be broken down by environmental processes * Food chain energetics – where the substance's concentration increases progressively as it moves up a food chain * Low or non-existent rate of internal degradation or excretion of the substance – mainly due to water-insolubility Biological magnification often refers to the process whereby certain substances such as pesticides or heavy metals work their way into lakes, rivers and the ocean, and then move up the food chain in progressively greater concentrations as they are incorporated into the diet of aquatic organisms such as zooplankton, which in turn are eaten perhaps by fish, which then may be eaten by bigger fish, large birds, ani ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crab
Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the world's oceans, in freshwater, and on land, are generally covered with a thick exoskeleton, and have a single pair of pincers. They first appeared during the Jurassic Period. Description Crabs are generally covered with a thick exoskeleton, composed primarily of highly mineralized chitin, and armed with a pair of chelae (claws). Crabs vary in size from the pea crab, a few millimeters wide, to the Japanese spider crab, with a leg span up to . Several other groups of crustaceans with similar appearances – such as king crabs and porcelain crabs – are not true crabs, but have evolved features similar to true crabs through a process known as carcinisation. Environment Crabs are found in all of the world's oceans, as well as in fres ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fish
Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of living fish species are ray-finned fish, belonging to the class Actinopterygii, with around 99% of those being teleosts. The earliest organisms that can be classified as fish were soft-bodied chordates that first appeared during the Cambrian period. Although they lacked a true spine, they possessed notochords which allowed them to be more agile than their invertebrate counterparts. Fish would continue to evolve through the Paleozoic era, diversifying into a wide variety of forms. Many fish of the Paleozoic developed external armor that protected them from predators. The first fish with jaws appeared in the Silurian period, after which many (such as sharks) became formidable marine predators rather than just the prey of arthropods. Most f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among the first life forms to appear on Earth, and are present in most of its habitats. Bacteria inhabit soil, water, acidic hot springs, radioactive waste, and the deep biosphere of Earth's crust. Bacteria are vital in many stages of the nutrient cycle by recycling nutrients such as the fixation of nitrogen from the atmosphere. The nutrient cycle includes the decomposition of dead bodies; bacteria are responsible for the putrefaction stage in this process. In the biological communities surrounding hydrothermal vents and cold seeps, extremophile bacteria provide the nutrients needed to sustain life by converting dissolved compounds, such as hydrogen sulphide and methane, to energy. Bacteria also live in symbiotic and parasitic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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