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Holomastigotoides Hartmanni
''Holomastigotoides'' is a genus of parabasalids found in the hindgut of lower termites. It is characterized by its dense, organized arrangement of flagella on the cell surface and the presence of a mitotic spindle outside its nucleus during the majority of its cell cycle. As a symbiont of termites, ''Holomastigotoides'' is able to ingest wood and aid its host in digestion. In return, ''Holomastigotoides'' is supplied with a stable habitat and steady supply of food. ''Holomastigotoides'' has notably been studied to observe the mechanisms of chromosomal pairing and segregation in haploid and diploid cells. Taxonomy ''Holomastigotoides'' was first described by Max Hartmann in 1910. Hartmann mistakenly identified ''Holomastigotoides'' as the female form of the parabasalid ''Trichonympha hertwigi'', which he observed living in a species of termite, ''Coptotermes sp.'', in Brazil. After initial discovery, Giovanni Battista Grassi and Anna Foa reclassified Hartmann's “male” form o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parabasalid
The parabasalids are a group of flagellated protists within the supergroup Excavata. Most of these eukaryotic organisms form a symbiotic relationship in animals. These include a variety of forms found in the intestines of termites and cockroaches, many of which have symbiotic bacteria that help them digest cellulose in woody plants. Other species within this supergroup are known parasites, and include human pathogens. Characteristics The flagella are arranged in one or more clusters near the anterior of the cell. Their basal bodies are linked to parabasal fibers that attach to prominent Golgi complexes, distinctive to the group. Usually they also give rise to a sheet of cross-like microtubules that runs down the center of the cell and in some cases projects past the end. This is called the axostyle, but is different in structure from the axostyles of oxymonads. Parabasalids are anaerobic, and lack mitochondria, but this is now known to be a result of secondary loss, and t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Psammotermes
''Psammotermes'' is a genus of termites in the family Rhinotermitidae. It is found living in subterranean nests in arid parts of Africa. Distribution and habitat ''Psammotermes'' is found in deserts and arid regions of Africa, in sand or eroded areas, but not heavy clay or alluvial soils. It is the termite genus best adapted for desert life and replaces ''Anacanthotermes'' in the driest areas. In is to be found in places with some vegetation or even where there is none, where it is believed to subsist on wind blown accumulations of organic detritus. It can live on buried timber, perhaps relics of a previous era when the climate was wetter. Behaviour ''Psammotermes'' colonies are underground nests consisting of chambers and narrow galleries that they excavate themselves, although they have been known to inhabit the disused nests of ''Amitermes'', '' Baucaliotermes'' and ''Trinervitermes''. They are generalist feeders and consume anything including animal dung, roadside litter (ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prorhinotermes Simplex
''Prorhinotermes simplex'', the Cuban subterranean termite, is a species of lower termite in the genus ''Prorhinotermes''. It is found in Colombia. Like others in its genus, it is a single-site nesting termite that moves to a new food source when theirs is gone, and it lacks a true worker caste. Caste Like all other members of ''Prorhinotermes'', ''P. simplex'' lacks a true worker caste (meaning permanently sterile workers) and has a linear ontogenetical pathway with a single Nymph (biology), nymphal instar. Soldiers typically arise from the late larval stage in mature colonies and can be identified from their marked wing rudiments. Each of their two molts from larva to soldier adds an antennae segment, and they contain a lot of the chemicals (E)-1-nitropentadec-1-ene, (E)-1-nitropentadecene and (''Z'',''E'')-α-Farnesene. They make up from 7-22% of each colony's population. They typically guard inside the nest, but they will come out as defenders if the nest is moved. Soldiers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monophyletic
In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic groups are typically characterised by shared derived characteristics ( synapomorphies), which distinguish organisms in the clade from other organisms. An equivalent term is holophyly. The word "mono-phyly" means "one-tribe" in Greek. Monophyly is contrasted with paraphyly and polyphyly as shown in the second diagram. A ''paraphyletic group'' consists of all of the descendants of a common ancestor minus one or more monophyletic groups. A '' polyphyletic group'' is characterized by convergent features or habits of scientific interest (for example, night-active primates, fruit trees, aquatic insects). The features by which a polyphyletic group is differentiated from others are not inherited from a common ancestor. These definitions have tak ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhinotermitidae
Rhinotermitidae is a family of termites (Isoptera). They feed on wood and can cause extensive damage to buildings or other wooden structures. About 345 species are recognized, among these are severe pests such as '' Coptotermes formosanus'', ''Coptotermes gestroi'', and ''Reticulitermes flavipes''. Subfamilies and Genera WikiSpecies and the ''Termite CatalogueTermite Catalogue (retrieved 12 July 2019)' list the following: Coptotermitinae Auth.: Holmgren, 1910 * ''Coptotermes'' Heterotermitinae Auth.: Froggatt, 1897 (synonym Leucotermitinae Holmgren, 1910a) * ''Heterotermes'' * ''Reticulitermes'' * '' Tsaitermes'' Prorhinotermitinae Auth.: Quennedey & Deligne, 1975 * ''Prorhinotermes'' Psammotermitinae Auth.: Holmgren, 1911 (Note: Holmgren included this taxon in "family Mesotermitidae") * '' Psammotermes'' Rhinotermitinae Auth.: Froggatt, 1897 * '' Acorhinotermes'' * '' Dolichorhinotermes'' * '' Macrorhinotermes'' * '' Parrhinotermes'' * ''Rhinotermes'' * ''Schedorhinotermes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Science (journal)
''Science'', also widely referred to as ''Science Magazine'', is the peer-reviewed academic journal of the American Association for the Advancement of Science (AAAS) and one of the world's top academic journals. It was first published in 1880, is currently circulated weekly and has a subscriber base of around 130,000. Because institutional subscriptions and online access serve a larger audience, its estimated readership is over 400,000 people. ''Science'' is based in Washington, D.C., United States, with a second office in Cambridge, UK. Contents The major focus of the journal is publishing important original scientific research and research reviews, but ''Science'' also publishes science-related news, opinions on science policy and other matters of interest to scientists and others who are concerned with the wide implications of science and technology. Unlike most scientific journals, which focus on a specific field, ''Science'' and its rival ''Nature (journal), Nature'' c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prophase
Prophase () is the first stage of cell division in both mitosis and meiosis. Beginning after interphase, DNA has already been replicated when the cell enters prophase. The main occurrences in prophase are the condensation of the chromatin reticulum and the disappearance of the nucleolus. Staining and microscopy Microscopy can be used to visualize condensed chromosomes as they move through meiosis and mitosis. Various DNA stains are used to treat cells such that condensing chromosomes can be visualized as the move through prophase. The giemsa G-banding technique is commonly used to identify mammalian chromosomes, but utilizing the technology on plant cells was originally difficult due to the high degree of chromosome compaction in plant cells. G-banding was fully realized for plant chromosomes in 1990. During both meiotic and mitotic prophase, giemsa staining can be applied to cells to elicit G-banding in chromosomes. Silver staining, a more modern technology, in conjunction ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kinetochore
A kinetochore (, ) is a disc-shaped protein structure associated with duplicated chromatids in eukaryotic cells where the spindle fibers attach during cell division to pull sister chromatids apart. The kinetochore assembles on the centromere and links the chromosome to microtubule polymers from the mitotic spindle during mitosis and meiosis. The term kinetochore was first used in a footnote in a 1934 Cytology book by Lester W. Sharp and commonly accepted in 1936. Sharp's footnote reads: "The convenient term ''kinetochore'' (= movement place) has been suggested to the author by J. A. Moore", likely referring to John Alexander Moore who had joined Columbia University as a freshman in 1932. Monocentric organisms, including vertebrates, fungi, and most plants, have a single centromeric region on each chromosome which assembles a single, localized kinetochore. Holocentric organisms, such as nematodes and some plants, assemble a kinetochore along the entire length of a chromosome. Ki ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mitochondrion
A mitochondrion (; ) is an organelle found in the cells of most Eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is used throughout the cell as a source of chemical energy. They were discovered by Albert von Kölliker in 1857 in the voluntary muscles of insects. The term ''mitochondrion'' was coined by Carl Benda in 1898. The mitochondrion is popularly nicknamed the "powerhouse of the cell", a phrase coined by Philip Siekevitz in a 1957 article of the same name. Some cells in some multicellular organisms lack mitochondria (for example, mature mammalian red blood cells). A large number of unicellular organisms, such as microsporidia, parabasalids and diplomonads, have reduced or transformed their mitochondria into other structures. One eukaryote, ''Monocercomonoides'', is known to have completely lost its mitochondria, and one multicellular organism, '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Division
Cell division is the process by which a parent cell (biology), cell divides into two daughter cells. Cell division usually occurs as part of a larger cell cycle in which the cell grows and replicates its chromosome(s) before dividing. In eukaryotes, there are two distinct types of cell division: a vegetative division (mitosis), producing daughter cells genetically identical to the parent cell, and a cell division that produces Haploidisation, haploid gametes for sexual reproduction (meiosis), reducing the number of chromosomes from two of each type in the diploid parent cell to one of each type in the daughter cells. In cell biology, mitosis (Help:IPA/English, /maɪˈtoʊsɪs/) is a part of the cell cycle, in which, replicated chromosomes are separated into two new Cell nucleus, nuclei. Cell division gives rise to genetically identical cells in which the total number of chromosomes is maintained. In general, mitosis (division of the nucleus) is preceded by the S stage of interph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Centrin
Centrins, also known as caltractins, are a family of calcium-binding phosphoproteins found in the centrosome of eukaryotes. Centrins are present in the centrioles and pericentriolar lattice. Human centrin genes are CETN1, CETN2 and CETN3. History Centrin was first isolated and characterized from the flagellar roots of the green alga ''Tetraselmis striata'' in 1984. Function Centrins are required for duplication of centrioles. They may also play a role in severing of microtubules by causing calcium-mediated contraction. The majority of centrin in the cell is non-centrosomal whose function is not yet clear. Structure Centrin belongs to the EF-hand superfamily of calcium-binding proteins and has four calcium-binding EF-hands. It has a molecular weight of 20 kDa. See also * Centriole * Centrosome In cell biology, the centrosome (Latin centrum 'center' + Greek sōma 'body') (archaically cytocentre) is an organelle that serves as the main microtubule organizing center (MTOC) of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phagocytosis
Phagocytosis () is the process by which a cell uses its plasma membrane to engulf a large particle (≥ 0.5 μm), giving rise to an internal compartment called the phagosome. It is one type of endocytosis. A cell that performs phagocytosis is called a phagocyte. In a multicellular organism's immune system, phagocytosis is a major mechanism used to remove pathogens and cell debris. The ingested material is then digested in the phagosome. Bacteria, dead tissue cells, and small mineral particles are all examples of objects that may be phagocytized. Some protozoa use phagocytosis as means to obtain nutrients. History Phagocytosis was first noted by Canadian physician William Osler (1876), and later studied and named by Élie Metchnikoff (1880, 1883). In immune system Phagocytosis is one main mechanisms of the innate immune defense. It is one of the first processes responding to infection, and is also one of the initiating branches of an adaptive immune response. Although mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
