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S. Mediterranea
''Schmidtea mediterranea'' is a freshwater triclad that lives in southern Europe and Tunisia. It is a model for regeneration, stem cells and development of tissues such as the brain and germline. Distribution ''Schmidtea mediterranea'' is found in some coastal areas and islands in the western Mediterranean (Catalonia, Menorca, Mallorca, Corsica, Sardinia, Sicily and Tunisia).Benazzi M, Baguñà J, Ballester R, Puccinelli I, Papa RD: Further Contribution to the Taxonomy of the ''Dugesia lugubris-polychroa Group'' with Description of ''Dugesia mediterranea'' n. sp. (Tricladida, Paludicola). Bolletino di zoologia 1975, 42(1):81-89.Ribas M: Cariologia, sistematica i biogeografia de les Planaries d'aigues dolces al Països Catalans. 1990.Baguñà J. Carranza S, Pala M, Ribera C, Giribet G, Arnedo M, Ribas M, Riutort M: From morphology and kariology to molecules. New methods for taxonomical identification of asexual populations of freshwater planarians. A tribute to Professor Mario Bena ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triclad
Planarians (triclads) are free-living flatworms of the class Turbellaria, order Tricladida, which includes hundreds of species, found in freshwater, marine, and terrestrial habitats.pp 3., "Planarians (the popular name for the group as a whole), or triclad flatworms (the more scientific designation of the same group), are acoelomate bilaterians". Planarians are characterized by a three-branched intestine, including a single anterior and two posterior branches. Their body is populated by adult stem cells called neoblasts, which planarians use for regenerating missing body parts. Many species are able to Regeneration (biology), regenerate any missing organ, which has made planarians a popular model in research of regeneration and stem cell biology. The genome sequences of several species are available, as are tools for molecular biology analysis. The order Tricladida is split into three suborders, according to their phylogenetic relationships: Maricola, Dimarcusidae, Cavernicola ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gastropod
Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and from the land. There are many thousands of species of sea snails and sea slug, slugs, as well as freshwater snails, freshwater limpets, land snails and slugs. The class Gastropoda is a diverse and highly successful class of mollusks within the phylum Mollusca. It contains a vast total of named species, second only to the insects in overall number. The fossil history of this class goes back to the Furongian, Late Cambrian. , 721 family (taxonomy), families of gastropods are known, of which 245 are extinct and appear only in the fossil record, while 476 are currently neontology, extant living fossil, with or without a fossil record. Gastropoda (previously known as univalves and sometimes spelled "Gasteropoda") are a major part of the phylum Mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dugesiidae
Dugesiidae is a family of freshwater planarians distributed worldwide (except Antarctica). The type genus is ''Dugesia ''Dugesia'' is a genus of freshwater planarians in the family Dugesiidae triclads and the type genus of this family. These common flatworms are found in freshwater habitats of Africa, Eurasia, and Australia. ''Dugesia'' is best known to non-spe ...'' Girard, 1850. Description All species of Dugesiidae live in freshwater environments and have a dorsoventrally flattened body. The head usually has a somewhat triangular shape and has two eyes (except for some subterranean eyeless species). The main differences between Dugesiidae and other freshwater planarians are related to the anatomy of the eyes and the copulatory apparatus. The eye cup in Dugesiidae is composed of several retinal cells, while in other freshwater planarians they are composed of a single cell. All freshwater planarians have an accessory organ called copulatory bursa or ''bursa copulatrix'', ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spindle Checkpoint
The spindle checkpoint, also known as the metaphase-to-anaphase transition, the spindle assembly checkpoint (SAC), the metaphase checkpoint, or the mitotic checkpoint, is a cell cycle checkpoint during metaphase of mitosis or meiosis that prevents the separation of the duplicated chromosomes (Mitosis#Anaphase, anaphase) until each chromosome is properly attached to the Spindle apparatus, spindle. To achieve proper segregation, the two kinetochores on the sister chromatids must be attached to opposite spindle poles (bipolar orientation). Only this pattern of attachment will ensure that each daughter cell (biology), cell receives one copy of the chromosome. The defining biochemical feature of this checkpoint is the stimulation of the anaphase-promoting complex by mitosis, M-phase Cyclin-dependent kinase complex, cyclin-CDK complexes, which in turn causes the proteolysis, proteolytic destruction of cyclins and proteins that hold the sister chromatids together. Overview and importan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fatty Acid
In chemistry, in particular in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated and unsaturated compounds#Organic chemistry, saturated or unsaturated. Most naturally occurring fatty acids have an Branched chain fatty acids, unbranched chain of an even number of carbon atoms, from 4 to 28. Fatty acids are a major component of the lipids (up to 70% by weight) in some species such as microalgae but in some other organisms are not found in their standalone form, but instead exist as three main classes of esters: triglycerides, phospholipids, and cholesteryl esters. In any of these forms, fatty acids are both important diet (nutrition), dietary sources of fuel for animals and important structural components for cell (biology), cells. History The concept of fatty acid (''acide gras'') was introduced in 1813 by Michel Eugène Chevreul, though he initially used some variant terms: ''graisse acide'' and ''acide huileux'' ("acid fat" and "oi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene
In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protein-coding genes and non-coding genes. During gene expression (the synthesis of Gene product, RNA or protein from a gene), DNA is first transcription (biology), copied into RNA. RNA can be non-coding RNA, directly functional or be the intermediate protein biosynthesis, template for the synthesis of a protein. The transmission of genes to an organism's offspring, is the basis of the inheritance of phenotypic traits from one generation to the next. These genes make up different DNA sequences, together called a genotype, that is specific to every given individual, within the gene pool of the population (biology), population of a given species. The genotype, along with environmental and developmental factors, ultimately determines the phenotype ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Long Terminal Repeat
A long terminal repeat (LTR) is a pair of identical sequences of DNA, several hundred base pairs long, which occur in eukaryotic genomes on either end of a series of genes or pseudogenes that form a retrotransposon or an endogenous retrovirus or a retroviral provirus. All retroviral genomes are flanked by LTRs, while there are some retrotransposons without LTRs. Typically, an element flanked by a pair of LTRs will encode a reverse transcriptase and an integrase, allowing the element to be copied and inserted at a different location of the genome. Copies of such an LTR-flanked element can often be found hundreds or thousands of times in a genome. LTR retrotransposons comprise about 8% of the human genome. The first LTR sequences were found by A.P. Czernilofsky and J. Shine in 1977 and 1980. Transcription The LTR-flanked sequences are partially transcribed into an RNA intermediate, followed by reverse transcription into complementary DNA (cDNA) and ultimately dsDNA (doubl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neoblast
Neoblasts (ˈniːəʊˌblæst) are adult stem cells found in planarian flatworms. They are the only dividing planarian cells, and they produce all cell types, including the germline. Neoblasts are abundant in the planarian parenchyma, and comprise up to 30 percent of all cells. Following injury, neoblasts rapidly divide and generate new cells, which allows planarians to regenerate any missing tissue. Characteristics Neoblasts are somatic adult stem cells that are abundant in planarians. Morphologically, neoblasts are round and small, 5 to 10 μm, and have a large nucleus and scant cytoplasm. They are the only dividing planarian cells. Neoblasts are found in the planarian parenchyma across the entire body, outside organ systems. The only regions that lack neoblasts completely are the pharynx and the head tip. Blastema formation New cells produced by dividing neoblasts form the regenerating blastema. Hours following the injury, a wound response is initiated. The initial wou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nematode
The nematodes ( or ; ; ), roundworms or eelworms constitute the phylum Nematoda. Species in the phylum inhabit a broad range of environments. Most species are free-living, feeding on microorganisms, but many are parasitic. Parasitic worms (helminths) are the cause of soil-transmitted helminthiases. They are classified along with arthropods, tardigrades and other moulting animals in the clade Ecdysozoa. Unlike the flatworms, nematodes have a tubular digestive system, with openings at both ends. Like tardigrades, they have a reduced number of Hox genes, but their sister phylum Nematomorpha has kept the ancestral protostome Hox genotype, which shows that the reduction has occurred within the nematode phylum. Nematode species can be difficult to distinguish from one another. Consequently, estimates of the number of nematode species are uncertain. A 2013 survey of animal biodiversity suggested there are over 25,000. Estimates of the total number of extant species are su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leech
Leeches are segmented parasitism, parasitic or Predation, predatory worms that comprise the Class (biology), subclass Hirudinea within the phylum Annelida. They are closely related to the Oligochaeta, oligochaetes, which include the earthworm, and like them have soft, muscular segmented bodies that can lengthen and contract. Both groups are hermaphrodites and have a clitellum, but leeches typically differ from the oligochaetes in having suckers at both ends and ring markings that do not correspond with their internal segmentation. The body is muscular and relatively solid; the coelom, the spacious body cavity found in other annelids, is reduced to small channels. The majority of leeches live in freshwater habitats, while some species can be found in terrestrial or marine environments. The best-known species, such as the medicinal leech, ''Hirudo medicinalis'', are hematophagous, attaching themselves to a host with a sucker and feeding on blood, having first secreted the pepti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Insect
Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, Thorax (insect anatomy), thorax and abdomen (insect anatomy), abdomen), three pairs of jointed Arthropod leg, legs, compound eyes, and a pair of antenna (biology), antennae. Insects are the most diverse group of animals, with more than a million described species; they represent more than half of all animal species. The insect nervous system consists of a insect brain, brain and a ventral nerve cord. Most insects reproduce Oviparous, by laying eggs. Insects Respiratory system of insects, breathe air through a system of Spiracle (arthropods), paired openings along their sides, connected to Trachea#Invertebrates, small tubes that take air directly to the tissues. The blood therefore does not carry oxygen; it is only partly contained in ves ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bivalve
Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed by a calcified exoskeleton consisting of a hinged pair of half-bivalve shell, shells known as valve (mollusc), valves. As a group, bivalves have no head and lack some typical molluscan organs such as the radula and the odontophore. Their gills have evolved into ctenidium (mollusc), ctenidia, specialised organs for feeding and breathing. Common bivalves include clams, oysters, Cockle (bivalve), cockles, mussels, scallops, and numerous other family (biology), families that live in saltwater, as well as a number of families that live in freshwater. Majority of the class are benthic filter feeders that bury themselves in sediment, where they are relatively safe from predation. Others lie on the sea floor or attach themselves to rocks or other h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
