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Polykrikoid
The Polykrikaceae (also known as Polykrikidae) are a family (biology), family of theca, athecate dinoflagellates of the order (biology), order Gymnodiniales. Members of the family are known as polykrikoids. The family contains two genera: ''Polykrikos'' and ''Pheopolykrikos''. Characteristics The most distinctive feature of polykrikoids is their formation of multinucleate "pseudocolonies" consisting of an even number of subunit zooids. The two genera differ in number of cell nucleus, nuclei; possessing two nuclei regardless of the number of zooids is a synapomorphy for ''Polykrikos'', whereas ''Pheopolykrikos'' possess equal numbers of nuclei and zooids. Along with the Warnowiaceae (warnowiids), polykrikoids are known for possessing unusually complex subcellular structures. In particular, an extrusome complex of two organelles called the nematocyst (dinoflagellate), nematocyst and taeniocyst is considered a synapomorphy for ''Polykrikos''. Molecular phylogenetics studies suggest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polykrikos
''Polykrikos'' (from Greek “poly” - many, and “krikos” – ring or circle) is one of the genera of family Polykrikaceae that includes athecate pseudocolony-forming dinoflagellates. ''Polykrikos'' are characterized by a sophisticated ballistic apparatus, named the nematocyst-taeniocyst complex, which allows species to prey on a variety of organisms. ''Polykrikos'' have been found to regulate algal blooms as they feed on toxic dinoflagellates. However, there is also some data available on Polykrikos being toxic to fish. History of knowledge ''Polykrikos'' was first seen in 1868 by Uljanin and was mistakenly considered as a metazoan larva of a turbellarian flatworms. In 1873 Butschili re-examined the specimen and concluded that the cell was an unusual ciliate, and Bergh later, in 1881, clarified ''Polykrikos'' dinoflagellate affinities. Morphology ''Polykrikos'' is a colony of zooids (units of a colonial organism) that carry out simultaneous functions of a whole cell. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polykrikos Kofoidii
''Polykrikos kofoidii'' is a species of phagotrophic marine pseudocolonial dinoflagellates that can capture and engulf other protist prey, including the toxic dinoflagellate, ''Alexandrium tamarense''. ''P. kofoidii'' is of scientific interest due to its status as a predator of other dinoflagellates, a behavior that is significant in the control of algal blooms. It has a complex life cycle of both vegetative (asexual) and sexual reproduction complicated by its pseudocolonial structure. References Species described in 1914 Gymnodiniales {{dinoflagellate-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nematocyst (dinoflagellate)
A nematocyst is a subcellular structure or organelle containing extrusive filaments found in two families of theca, athecate dinoflagellates (a group of unicellular eukaryotes), the Warnowiaceae and Polykrikaceae. It is distinct from the similar subcellular structures found in the cnidocyte cells of cnidarians, a group of multicellular organisms including jellyfish and corals; such structures are also often called nematocysts (alternatively, ''cnidocysts'' or ''cnidae''), and cnidocytes are sometimes referred to as nematocytes. It is unclear whether the relationship between dinoflagellate and cnidarian nematocysts is a case of convergent evolution or common descent, although molecular evidence has been interpreted as supporting an endosymbiotic origin for cnidarian nematocysts. In polykrikoids the nematocyst is found associated with another extrusive organelle called the taeniocyst, a complex that has been described as synapomorphic for the genus (biology), genus ''Polykrikos''. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Warnowiaceae
The Warnowiaceae are a family of athecate dinoflagellates (a diverse group of unicellular eukaryotes). Members of the family are known as warnowiids. The family is best known for a light-sensitive subcellular structure known as the ocelloid, a highly complex arrangement of organelles with a structure directly analogous to the eyes of multicellular organisms. The ocelloid has been shown to be composed of multiple types of endosymbionts, namely mitochondria and at least one type of plastid. Habitat and life cycle Warnowiids are found in marine plankton but are very rare in most plankton samples. Little is known about their life histories because they cannot be cultured in the laboratory, and samples obtained from the natural environment do not survive well under laboratory conditions. Studies of wild samples have found evidence of distinctive structures called trichocysts in warnowiid cell vacuoles, suggesting that their prey might be other dinoflagellates. Despite the complexity o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extrusome
Extrusomes are membrane-bound structures in some eukaryotes which, under certain conditions, discharge their contents outside the cell. There are a variety of different types, probably not homologous, and serving various functions. Notable extrusomes include mucocysts, which discharge a mucous mass sometimes used in cyst formation, and trichocysts, which discharge a fibrous rod. The stinging nematocysts found in Cnidarian animals may be regarded as extrusomes as well. Extrusomes found in dinoflagellate The dinoflagellates (Greek δῖνος ''dinos'' "whirling" and Latin ''flagellum'' "whip, scourge") are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered algae. Dinoflagellates are ...s are important in the formation of red and black tides. References External links Image: extrusome (labeled EX) Organelles {{Protist structures ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organelle
In cell biology, an organelle is a specialized subunit, usually within a cell, that has a specific function. The name ''organelle'' comes from the idea that these structures are parts of cells, as organs are to the body, hence ''organelle,'' the suffix ''-elle'' being a diminutive. Organelles are either separately enclosed within their own lipid bilayers (also called membrane-bound organelles) or are spatially distinct functional units without a surrounding lipid bilayer (non-membrane bound organelles). Although most organelles are functional units within cells, some function units that extend outside of cells are often termed organelles, such as cilia, the flagellum and archaellum, and the trichocyst. Organelles are identified by microscopy, and can also be purified by cell fractionation. There are many types of organelles, particularly in eukaryotic cells. They include structures that make up the endomembrane system (such as the nuclear envelope, endoplasmic reticulum, and G ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molecular Phylogenetics
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 frame ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Taxonomy (biology)
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, as he developed a ranked system known as Linnaean taxonomy for categorizing organisms and binomial nomenclature for naming 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 evolu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Light Microscopy
Microscopy is the technical field of using microscopes to view objects and areas of objects that cannot be seen with the naked eye (objects that are not within the resolution range of the normal eye). There are three well-known branches of microscopy: optical microscope, optical, electron microscope, electron, and scanning probe microscopy, along with the emerging field of X-ray microscopy. Optical microscopy and electron microscopy involve the diffraction, reflection (physics), reflection, or refraction of electromagnetic radiation/electron beams interacting with the Laboratory specimen, specimen, and the collection of the scattered radiation or another signal in order to create an image. This process may be carried out by wide-field irradiation of the sample (for example standard light microscopy and transmission electron microscope, transmission electron microscopy) or by scanning a fine beam over the sample (for example confocal laser scanning microscopy and scanning electro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plankton
Plankton are the diverse collection of organisms found in Hydrosphere, water (or atmosphere, air) that are unable to propel themselves against a Ocean current, current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucial source of food to many small and large aquatic organisms, such as bivalves, fish and whales. Marine plankton include bacteria, archaea, algae, protozoa and drifting or floating animals that inhabit the saltwater of oceans and the brackish waters of estuaries. Freshwater plankton are similar to marine plankton, but are found in the freshwaters of lakes and rivers. Plankton are usually thought of as inhabiting water, but there are also airborne versions, the aeroplankton, that live part of their lives drifting in the atmosphere. These include plant spores, pollen and wind-scattered seeds, as well as microorganisms swept into the air from terrestrial dust storms and oceanic plankton swept into the air ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photosynthetic
Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in carbohydrate molecules, such as sugars and starches, which are synthesized from carbon dioxide and water – hence the name ''photosynthesis'', from the Greek ''phōs'' (), "light", and ''synthesis'' (), "putting together". Most plants, algae, and cyanobacteria perform photosynthesis; such organisms are called photoautotrophs. Photosynthesis is largely responsible for producing and maintaining the oxygen content of the Earth's atmosphere, and supplies most of the energy necessary for life on Earth. Although photosynthesis is performed differently by different species, the process always begins when energy from light is absorbed by proteins called reaction centers that contain green chlorophyll (and other colored) pigments/chromophores. I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
