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Strombomonas
''Strombomonas'' is a genus of free-living euglenoids characterized by the presence of a shell-like covering called a lorica. It is found in freshwater habitats, and has a cosmopolitan distribution; about 100 species are accepted. Description ''Strombomonas'' consists of solitary, free-living cells surrounded by a shell, called a lorica. The lorica has an apical opening where the flagellum emerges. The cells themselves are mostly 25–50 μm long and 15–35 μm wide, and are mostly like ''Euglena'' in terms of morphology. They contain numerous greenish chloroplasts with pyrenoids, although this can often be difficult to see through the lorica. The lorica is sac- or vase-shaped, with a neck and tailpiece of varying lengths. The lorica aggregates particles on its outer surface, giving it a scabrous (rough) texture; the lorica also lacks spines, pores or pits, although it may have wrinkles. The lorica start off colorless but can often yellowish to brownish due to the impregnatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trachelomonas
''Trachelomonas'' is a genus of swimming, free-living euglenoids characterized by the presence of a shell-like covering called a Lorica (biology), lorica. Details of lorica structure determine the classification of distinct species in the genus. The lorica can exist in spherical, elliptical, cylindrical, and pyriform (pear-shaped) forms. The lorica surface can be smooth, punctuate or striate and range from hyaline, to yellow, or brown. These colors are due to the accumulation of ferric hydroxide and manganic oxide deposited with the mucilage and minerals that comprise the lorica. In ''Trachelomonas'', the presence of a lorica obscures cytoplasmic details of the underlying cell. In each ''Trachelomonas'' cell, there is a gap at the apex of the lorica from which the flagellum protrudes. Thickening around this gap results in a rim-like or collar-like appearance. During asexual reproduction, the cell nucleus, nucleus divides yielding two daughter cells one of which exits through the o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Euglenoid
Euglenids or euglenoids are one of the best-known groups of eukaryotic flagellates: single-celled organisms with flagella, or whip-like tails. They are classified in the phylum Euglenophyta, class Euglenida or Euglenoidea. Euglenids are commonly found in fresh water, especially when it is rich in organic materials, but they have a few marine and endosymbiotic members. Many euglenids feed by phagocytosis, or strictly by diffusion. A monophyletic subgroup known as Euglenophyceae have chloroplasts and produce their own food through photosynthesis. This group contains the carbohydrate paramylon. Euglenids split from other Euglenozoa (a larger group of flagellates) more than a billion years ago. The plastids (membranous organelles) in all extant photosynthetic species result from secondary endosymbiosis between a euglenid and a green alga. Structure Euglenoids are distinguished mainly by the presence of a type of cell covering called a pellicle. Within its taxon, the pellicle is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lorica (biology)
In biology, a lorica is a shell-like protective outer covering, often reinforced with sand grains and other particles that some protozoans and loriciferan animals secrete. Usually it is tubular or conical in shape, with a loose case that is closed at one end. An example is the protozoan genus '' Stentor'', in which the lorica is trumpet-shaped. In the tintinnids, the lorica is frequently transparent and is used as a domicile. '' Halofolliculina corallasia'' has a lorica that is attached as an outer structure, and into which it retracts when disturbed. Formation process There are three phases in the formation of lorica: agglomeration in a natural cast; helical extension; and stabilization. Agglomeration During agglomeration, the organism collects and assembles particles from its environment. These particles are then used to construct the initial framework of the lorica. Helical extension In the helical extension phase, the lorica is extended and shaped, often with a hel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Freshwater
Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mineral-rich waters, such as chalybeate springs. Fresh water may encompass frozen and meltwater in ice sheets, ice caps, glaciers, snowfields and icebergs, natural precipitations such as rainfall, snowfall, hail/ sleet and graupel, and surface runoffs that form inland bodies of water such as wetlands, ponds, lakes, rivers, streams, as well as groundwater contained in aquifers, subterranean rivers and lakes. Water is critical to the survival of all living organisms. Many organisms can thrive on salt water, but the great majority of vascular plants and most insects, amphibians, reptiles, mammals and birds need fresh water to survive. Fresh water is the water resource that is of the most and immediate use to humans. Fresh water is n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cosmopolitan Distribution
In biogeography, a cosmopolitan distribution is the range of a taxon that extends across most or all of the surface of the Earth, in appropriate habitats; most cosmopolitan species are known to be highly adaptable to a range of climatic and environmental conditions, though this is not always so. Killer whales ( orcas) are among the most well-known cosmopolitan species on the planet, as they maintain several different resident and transient (migratory) populations in every major oceanic body on Earth, from the Arctic Circle to Antarctica and every coastal and open-water region in-between. Such a taxon (usually a species) is said to have a ''cosmopolitan'' distribution, or exhibit cosmopolitanism, as a species; another example, the rock dove (commonly referred to as a ' pigeon'), in addition to having been bred domestically for centuries, now occurs in most urban areas around the world. The extreme opposite of a cosmopolitan species is an endemic (native) species, or one foun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flagellum
A flagellum (; : flagella) (Latin for 'whip' or 'scourge') is a hair-like appendage that protrudes from certain plant and animal sperm cells, from fungal spores ( zoospores), and from a wide range of microorganisms to provide motility. Many protists with flagella are known as flagellates. A microorganism may have from one to many flagella. A gram-negative bacterium '' Helicobacter pylori'', for example, uses its flagella to propel itself through the stomach to reach the mucous lining where it may colonise the epithelium and potentially cause gastritis, and ulcers – a risk factor for stomach cancer. In some swarming bacteria, the flagellum can also function as a sensory organelle, being sensitive to wetness outside the cell. Across the three domains of Bacteria, Archaea, and Eukaryota, the flagellum has a different structure, protein composition, and mechanism of propulsion but shares the same function of providing motility. The Latin word means " whip" to describe its ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chloroplast
A chloroplast () is a type of membrane-bound organelle, organelle known as a plastid that conducts photosynthesis mostly in plant cell, plant and algae, algal cells. Chloroplasts have a high concentration of chlorophyll pigments which capture the Radiant energy, energy from sunlight and convert it to chemical energy and release oxygen. The chemical energy created is then used to make sugar and other organic molecules from carbon dioxide in a process called the Calvin cycle. Chloroplasts carry out a number of other functions, including fatty acid synthesis, amino acid synthesis, and the immune response in plants. The number of chloroplasts per cell varies from one, in some unicellular algae, up to 100 in plants like ''Arabidopsis'' and wheat. Chloroplasts are highly dynamic—they circulate and are moved around within cells. Their behavior is strongly influenced by environmental factors like light color and intensity. Chloroplasts cannot be made anew by the plant cell and must ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrenoid
Pyrenoids are sub-cellular phase-separated micro-compartments found in chloroplasts of many algae,Giordano, M., Beardall, J., & Raven, J. A. (2005). CO2 concentrating mechanisms in algae: mechanisms, environmental modulation, and evolution. ''Annu. Rev. Plant Biol.'', 56, 99-131. and in a single group of land plants, the hornworts.Villarreal, J. C., & Renner, S. S. (2012) Hornwort pyrenoids, carbon-concentrating structures, evolved and were lost at least five times during the last 100 million years. ''Proceedings of the National Academy of Sciences'',109(46), 1873-1887. Pyrenoids are associated with the operation of a carbon-concentrating mechanism (CCM). Their main function is to act as centres of carbon dioxide (CO2) fixation, by generating and maintaining a CO2-rich environment around the photosynthesis, photosynthetic enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO). Pyrenoids therefore seem to have a role analogous to that of carboxysomes in cyanobacteria. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Georges Deflandre
Georges may refer to: Places *Georges River, New South Wales, Australia * Georges Quay (Dublin) *Georges Township, Fayette County, Pennsylvania Other uses * Georges (name) * ''Georges'' (novel), a novel by Alexandre Dumas * "Georges" (song), a 1977 song originally recorded by Pat Simon and covered by Sylvie Vartan * Georges (store), a department store in Melbourne, Australia from 1880 to 1995 * Georges (''Green Card'' character) People with the surname * Eugenia Georges, American anthropologist *Karl Ernst Georges (1806–1895), German classical philologist and lexicographer, known for his edition of Latin-German dictionaries. * Mary Ngwanda Georges, Congo-born American politician See also * École secondaire Georges-P.-Vanier, a high school in Hamilton, Ontario, Canada *École secondaire Georges-Vanier in Laval, Quebec, Canada * French cruiser ''Georges Leygues'', commissioned in 1937 * French frigate ''Georges Leygues'' (D640), commissioned in 1979 * Georges Krayem, Brazilian l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sister Clade
In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and taxon B are sister groups to each other. Taxa A and B, together with any other extant or extinct descendants of their most recent common ancestor (MRCA), form a monophyletic group, the clade AB. Clade AB and taxon C are also sister groups. Taxa A, B, and C, together with all other descendants of their MRCA form the clade ABC. The whole clade ABC is itself a subtree of a larger tree which offers yet more sister group relationships, both among the leaves and among larger, more deeply rooted clades. The tree structure shown connects through its root to the rest of the universal tree of life. In cladistic standards, taxa A, B, and C may represent specimens, species, genera, or any other taxonomic units. If A and B are at the same taxonomic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molecular Phylogenetic
Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to determine the processes by which diversity among species has been achieved. The result of a molecular phylogenetic analysis is expressed in a phylogenetic tree. Molecular phylogenetics is one aspect of molecular systematics, a broader term that also includes the use of molecular data in taxonomy and biogeography. Molecular phylogenetics and molecular evolution correlate. Molecular evolution is the process of selective changes (mutations) at a molecular level (genes, proteins, etc.) throughout various branches in the tree of life (evolution). Molecular phylogenetics makes inferences of the evolutionary relationships that arise due to molecular evolution and results in the construction of a phylogenetic tree. History The theoretical fra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Taxonomic Revision
In biology, taxonomy () is the scientific study of naming, defining ( circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxa (singular: taxon), and these groups are given a taxonomic rank; groups of a given rank can be aggregated to form a more inclusive group of higher rank, thus creating a taxonomic hierarchy. The principal ranks in modern use are domain, kingdom, phylum (''division'' is sometimes used in botany in place of ''phylum''), class, order, family, genus, and species. The Swedish botanist Carl Linnaeus is regarded as the founder of the current system of taxonomy, having developed a ranked system known as Linnaean taxonomy for categorizing organisms. With advances in the theory, data and analytical technology of biological systematics, the Linnaean system has transformed into a system of modern biological classification intended to reflect the evolutionary relationships among organisms, both liv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
