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Myxosporea
Myxosporea is a class of microscopic parasites, belonging to the Myxozoa clade within Cnidaria. They have a complex life cycle which comprises vegetative forms in two hosts, an aquatic invertebrate (generally an annelid but sometimes a bryozoan) and an ectothermic vertebrate, usually a fish. Each host releases a different type of spore. The two forms of spore are so different that until relatively recently they were treated as belonging to different classes within the Myxozoa. Taxonomic status The taxonomy of both actinosporeans and myxosporeans was originally based on spore morphology. In 1994 the phylum Myxozoa was redefined to solve the taxonomic and nomenclatural problems arising from the two-host life cycle of myxozoans. The distinction between the two previously recognised classes Actinosporea and Myxosporea disappeared and the class ''Actinosporea'' was suppressed, becoming a synonym of the class ''Myxosporea'' (Bütschli, 1881). The generic names of actinosporeans were r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myxozoa
Myxozoa (etymology: Greek: μύξα ''myxa'' "slime" or "mucus" + thematic vowel o + ζῷον ''zoon'' "animal") is a subphylum of aquatic cnidarian animals – all obligate parasites. It contains the smallest animals ever known to have lived. Over 2,180 species have been described and some estimates have suggested at least 30,000 undiscovered species. Many have a two-host lifecycle, involving a fish and an annelid worm or a bryozoan. The average size of a myxosporean spore usually ranges from 10 μm to 20 μm, whereas that of a malacosporean (a subclade of the Myxozoa) spore can be up to 2 mm. Myxozoans can live in both freshwater and marine habitats. Myxozoans are highly derived cnidarians that have undergone dramatic evolution from a free swimming, self-sufficient jellyfish-like creature into their current form of obligate parasites composed of very few cells – sometimes only a single cell. As myxozoans evolved into microscopic parasites, they lost many g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kudoa Septempunctata
''Kudoa'' is a genus of Myxozoa and the only genus recognized within the monotypic family Kudoidae. There are approximately 100 species of ''Kudoa'' all of which parasitize on marine and estuarine fish. ''Kudoa'' are most commonly known and studied for the negative effects the genus has on commercial fishing and aquaculture industries. Description The genus ''Kudoa'' is identified by the possession of four or more shell valves composed of a fragile membrane and arranged in a quadrate or stellate pattern. The maximum number of shell valves in any described ''Kudoa'' species is 13. Each of these valves has a polar capsule. The genus ''Kudoa'' was originally part of the genus '' Chloromyxum'' because of the distribution of their polar capsules, however, it was later determined to be a separate genus. Each ''Kudoa'' has two sporoplasm cells, one enclosed by the other. Most ''Kudoa'' are histozoic parasites, with a few species being described as coelzoic. Some taxonomists questi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kudoa
''Kudoa'' is a genus of Myxozoa and the only genus recognized within the monotypic family Kudoidae. There are approximately 100 species of ''Kudoa'' all of which parasitize on marine and estuarine fish. ''Kudoa'' are most commonly known and studied for the negative effects the genus has on commercial fishing and aquaculture industries. Description The genus ''Kudoa'' is identified by the possession of four or more shell valves composed of a fragile membrane and arranged in a quadrate or stellate pattern. The maximum number of shell valves in any described ''Kudoa'' species is 13. Each of these valves has a polar capsule. The genus ''Kudoa'' was originally part of the genus ''Chloromyxum'' because of the distribution of their polar capsules, however, it was later determined to be a separate genus. Each ''Kudoa'' has two sporoplasm cells, one enclosed by the other. Most ''Kudoa'' are histozoic parasites, with a few species being described as coelzoic. Some taxonomists question w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bivalvulida
Bivalvulida is an order of myxosporean parasites which contains a number of species which cause economically significant losses to aquaculture and fisheries, such as ''Myxobolus cerebralis'' and ''Ceratomyxa shasta''. The Myxosporean stages of members of the bivalvulida are characterised by their two spore valves (hence the name), which meet in a "suture line" which encircles the spore. They usually contain two polar capsules, but species have been reported which contain either one or four. Taxonomy and systematics The order Bivalvulida is composed of three suborders and thirteen families. *Suborder Platysporina Kudo, 1919Kudo, R. (1919). Studies on Myxosporidia. A synopsis of genera and species of Myxosporidia. ''Illinois Biological Monographs'', 5. **Myxobolidae Thélohan, 1892Thélohan, P. (1892). Observation sur les myxosporidies et essai de classification de ces organismes. ''Bulletin de la Société Philomatique de Paris'', 4, 165–178. *Suborder Sphaeromyxina Lom & Noble, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ceratonova Shasta
''Ceratonova shasta'' (syn. ''Ceratomyxa shasta'') is a myxosporean parasite that infects salmonid fish on the Pacific coast of North America. It was first observed at the Crystal Lake Hatchery, Shasta County, California, and has now been reported from Idaho, Oregon, Washington, British Columbia and Alaska. Life history In addition to the fish host, ''C. shasta'' infects a freshwater polychaete worm. Actinospores are released from the worm, and infect fish, on contact, in the water column. Neither horizontal (fish to fish), nor vertical (fish to egg) transmissions have been documented under laboratory conditions, suggesting that the worm host is necessary for completion of the life cycle. Spores are released back into freshwater system after its fish host dies, however the complete life cycle, host and vector interaction is not fully understood (especially the ecology of the polychaete host). Research indicates that the potential for infection is enhanced when water temperature ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myxobolus Cerebralis
''Myxobolus cerebralis'' is a myxosporean parasite of salmonids (salmon and trout species) that causes whirling disease in farmed salmon and trout and also in wild fish populations. It was first described in rainbow trout in Germany in 1893, but its range has spread and it has appeared in most of Europe (including Russia), the United States, South Africa, Canada and other countries due to the aid of humans of shipments of cultured and wild fish. In the 1980s, ''M. cerebralis'' was found to require a tubificid oligochaete (a kind of segmented worm) to complete its life cycle. The parasite infects its hosts with its cells after piercing them with polar filaments ejected from nematocyst-like capsules. This infects the cartilage and possibly the nervous tissue of salmonids, causing a potentially lethal infection. Causing the host to develop a black tail, spinal deformities, and possible more deformities in the anterior part of the fish. Whirling disease affects juvenile fish (fin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multivalvulida
Multivalvulida is an order of myxozoan. Families * Kudoidae ''Kudoa'' is a genus of Myxozoa and the only genus recognized within the monotypic family Kudoidae. There are approximately 100 species of ''Kudoa'' all of which parasitize on marine and estuarine fish. ''Kudoa'' are most commonly known and studi ... * Spinavaculidae * Trilosporidae ReferencesEncyclopedia of Life entry Myxosporea Cnidarian orders {{Myxozoa-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clonally Transmissible Cancer
A transmissible cancer is a cancer cell or cluster of cancer cells that can be transferred between individuals without the involvement of an infectious agent, such as an oncovirus. Transmission of cancer between humans is rare. The evolution of transmissible cancer has occurred naturally in other animal species, but human cancer transmission is rare. Humans In humans, a significant fraction of Kaposi's sarcoma occurring after transplantation may be due to tumorous outgrowth of donor cells. Although Kaposi's sarcoma is caused by a virus (Kaposi's sarcoma-associated herpesvirus), in these cases, it appears likely that transmission of virus-infected tumor cells—rather than the free virus—caused tumors in the transplant recipients. In 2007, four people (3 women & 1 man) received different organ transplants (liver, both lungs and kidneys) from a 53-year-old woman who had recently died from intracranial bleeding. Before transplantation, the organ donor was deemed to have no signs of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quanta Magazine
''Quanta Magazine'' is an editorially independent online publication of the Simons Foundation covering developments in physics, mathematics, biology and computer science. ''Undark Magazine'' described ''Quanta Magazine'' as "highly regarded for its masterful coverage of complex topics in science and math." The science news aggregator ''RealClearScience'' ranked ''Quanta Magazine'' first on its list of "The Top 10 Websites for Science in 2018." In 2020, the magazine received a National Magazine Award for General Excellence from the American Society of Magazine Editors for its "willingness to tackle some of the toughest and most difficult topics in science and math in a language that is accessible to the lay reader without condescension or oversimplification." The articles in the magazine are freely available to read online. ''Scientific American'', ''Wired'', ''The Atlantic'', and ''The Washington Post'', as well as international science publications like ''Spektrum der Wissensch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Species Inqueranda
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. The most recent rigorous estimate for the total number of species of eukaryotes is between 8 and 8.7 million. However, only about 14% of these had been described by 2011. All species (except viruses) are given a two-part name, a "binomial". The first part of a binomial is the genus to which the species belongs. The second part is called the specific name or the specific epithet (in botanical nomenclature, also sometimes in zool ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polypodium (animal)
''Polypodium'' is a genus of cnidarians that parasitizes in the eggs of sturgeon and similar fishes (Acipenseridae and Polyodontidae). It is one of the few metazoans (animals) that live inside the cells of other animals. ''Polypodium hydriforme'' is the only species of this monotypic genus. The parent family (Polypodiidae), order (Polypodiidea) and class (Polypodiozoa) are also monotypic. Taxonomy Unusual characteristics have led to much controversy regarding the phylogenetic position of ''Polypodium'' within metazoans. ''Polypodium'' has traditionally been considered a cnidarian because it possesses nematocysts, the stinging structures characteristic of this phylum. Molecular phylogenetic studies using 18S rDNA sequence data temporarily challenged this interpretation, by finding that ''Polypodium'' is a close relative to myxozoans and suggesting that together they share a closer affinity to bilaterians than cnidarians. Due to the variable rates of 18S rDNA sequences, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Salmonid
Salmonidae is a family of ray-finned fish that constitutes the only currently extant family in the order Salmoniformes . It includes salmon (both Atlantic and Pacific species), trout (both ocean-going and landlocked), chars, freshwater whitefishes, graylings, taimens and lenoks, which are collectively known as the salmonids ("salmon-like fish"). The Atlantic salmon (''Salmo salar''), whose Latin name became that of its genus ''Salmo'', is also the source of the family and order names. Salmonids have a relatively primitive appearance among the teleost fish, with the pelvic fins being placed far back, and an adipose fin towards the rear of the back. They have slender bodies, with rounded scales and forked tails, and their mouths contain a single row of sharp teeth. Although the smallest species is just long as an adult, most are much larger, with the largest reaching . All salmonids spawn in fresh water of upper reaches of rivers and creeks, but in many cases, the fish spen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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