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Müllerian Vesicle
Loxodidae is a family of karyorelict ciliates. Loxodidae members possess an elongated, laterally flattened shape. They share two key characters: a beak-like anterior rostrum interrupting the perioral kineties, and peculiar cytoplasmic organelles named Müller vesicles. The extensive development of lacunae of the smooth endoplasmic reticulum leads to strong vacuolization of the endoplasm. This feature is associated to a lack of contractile vacuoles in all loxodids. The term ''Loxodidae'' derives from the ancient Greek (), meaning "oblique, tilted". Gravitaxis Loxodidae members possess the ability to orient themselves in oxygen gradients. They use gravity as a stimulus for this spatial orientation, a phenomenon called gravitaxis or geotaxis. Loxodid ciliates must therefore have developed mechanoreceptors informing them about what is up or down. A likely candidate structure for their gravitaxis is the Müller vesicle. Müller vesicle Müller vesicles (also known as Mü ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Loxodes
''Loxodes'' is a genus of karyorelictean ciliates, belonging to Loxodidae. It is the only known karyorelictean ciliate that lives in freshwater habitats. The genus is known for its distinctive morphology, including a relatively large, flattened body and unique nuclear structures. It is also known to exhibit fascinating behaviours, such as geotaxis and light sensitivity. Etymology The term ''Loxodes'' derives from the ancient greek (), meaning "oblique, tilted". According to Ehrenberg, who first described the genus, Loxodes means oblique and refers to the anterior margin of the ciliated lip of the organisms in this genus. Type species ''Loxodes rostrum'' (Müller, 1773) Ehrenberg, 1830 History of knowledge ''Kolpoda rostrum'' was the first loxodid discovered and described. The genus ''Loxodes'' was first proposed in 1830. Ehrenberg moved ''Kolpoda rostrum'' into the genus ''Loxodes'' and set it as the type species. Research has explored the geotaxis of ''Loxodes'' species ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Statocyst
The statocyst is a balance sensory receptor present in some aquatic invertebrates, including bivalves, cnidarians, ctenophorans, echinoderms, cephalopods, crustaceans, and gastropods, A similar structure is also found in '' Xenoturbella''. The statocyst consists of a sac-like structure containing a mineralised mass (statolith) and numerous innervated sensory hairs ( setae). The statolith's inertia causes it to push against the setae when the animal accelerates. Deflection of setae by the statolith in response to gravity activates neurons, providing feedback to the animal on change in orientation and allowing balance to be maintained. In other words, the statolith shifts as the animal moves. Any movement large enough to throw the organism off balance causes the statolith to brush against tiny bristles which in turn send a message to the brain to correct its balance. It may have been present in the common ancestor of cnidarians and bilaterians. Hearing In cephalopods like s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monophyletic
In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent common ancestor (or more precisely an ancestral population), i.e. excludes non-descendants of that common ancestor # the grouping contains all the descendants of that common ancestor, without exception Monophyly is contrasted with paraphyly and polyphyly as shown in the second diagram. A ''paraphyletic'' grouping meets 1. but not 2., thus consisting of the descendants of a common ancestor, excepting one or more monophyletic subgroups. A '' polyphyletic'' grouping meets neither criterion, and instead serves to characterize convergent relationships of biological features rather than genetic relationships – for example, night-active primates, fruit trees, or aquatic insects. As such, these characteristic features of a polyphyletic grouping ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
18S Ribosomal RNA
18S ribosomal RNA (abbreviated 18S rRNA) is a part of the ribosomal RNA in eukaryotes. It is a component of the Eukaryotic small ribosomal subunit (40S) and the cytosolic homologue of both the 12S ribosomal RNA, 12S rRNA in mitochondria and the 16S ribosomal RNA, 16S rRNA in plastids and prokaryotes. Similar to the prokaryotic 16S rRNA, the genes of the 18S ribosomal RNA have been widely used for Phylogenetics, phylogenetic studies and biodiversity screening of eukaryotes. Research history Along with the 28S ribosomal RNA, 28S and 5.8S ribosomal RNA, 5.8S rRNA in eukaryotes, the 18S rRNA was early identified as integral structural element of ribosomes which were first characterized by their sedimentation properties and named according to measured Svedberg, Svedberg units. Given its ubiquitous presence in eukaryotic life, the evolution of the 18S rRNA was soon proposed as marker for phylogenetics, phylogenetic studies to resolve the evolution of eukaryotes. Structure and function ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barium
Barium is a chemical element; it has symbol Ba and atomic number 56. It is the fifth element in group 2 and is a soft, silvery alkaline earth metal. Because of its high chemical reactivity, barium is never found in nature as a free element. The most common minerals of barium are barite ( barium sulfate, BaSO4) and witherite ( barium carbonate, BaCO3). The name ''barium'' originates from the alchemical derivative "baryta", from Greek (), meaning 'heavy'. ''Baric'' is the adjectival form of barium. Barium was identified as a new element in 1772, but not reduced to a metal until 1808 with the advent of electrolysis. Barium has few industrial applications. Historically, it was used as a getter for vacuum tubes and in oxide form as the emissive coating on indirectly heated cathodes. It is a component of YBCO (high-temperature superconductors) and electroceramics, and is added to steel and cast iron to reduce the size of carbon grains within the microstructure. Barium compounds ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Strontium
Strontium is a chemical element; it has symbol Sr and atomic number 38. An alkaline earth metal, it is a soft silver-white yellowish metallic element that is highly chemically reactive. The metal forms a dark oxide layer when it is exposed to air. Strontium has physical and chemical properties similar to those of its two vertical neighbors in the periodic table, calcium and barium. It occurs naturally mainly in the minerals celestine and strontianite, and is mostly mined from these. Both strontium and strontianite are named after Strontian, a village in Scotland near which the mineral was discovered in 1790 by Adair Crawford and William Cruickshank; it was identified as a new element the next year from its crimson-red flame test color. Strontium was first isolated as a metal in 1808 by Humphry Davy using the then newly discovered process of electrolysis. During the 19th century, strontium was mostly used in the production of sugar from sugar beets (see strontian proces ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kinety
The ciliates are a group of alveolates characterized by the presence of hair-like organelles called cilia, which are identical in structure to eukaryotic flagella, but are in general shorter and present in much larger numbers, with a different undulating pattern than flagella. Cilia occur in all members of the group (although the peculiar Suctoria only have them for part of their life cycle) and are variously used in swimming, crawling, attachment, feeding, and sensation. Ciliates are an important group of protists, common almost anywhere there is water—in lakes, ponds, oceans, rivers, and soils, including anoxic and oxygen-depleted habitats. About 4,500 unique free-living species have been described, and the potential number of extant species is estimated at 27,000–40,000. Included in this number are many ectosymbiotic and endosymbiotic species, as well as some obligate and opportunistic parasites. Ciliate species range in size from as little as 10 μm in some colpodeans ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eugène Penard
Eugène Penard (16 September 1855 – 5 January 1954) was a Swiss biologist and pioneer in systematics of the amoebae. Penard was born in Geneva where his father ran a private school. After studying in Geneva, Eugène worked in a bank but decided to pursue science and went to the University of Edinburgh followed by studies at the University of Heidelberg under Otto Bütschli Johann Adam Otto Bütschli (3 May 1848 – 2 February 1920) was a German zoologist and professor at the University of Heidelberg. He specialized in invertebrates and insect development. Many of the groups of protists were first recognized by him. .... He then became a student of Karl Vogt in Geneva from 1882 with a break serving as a private tutor to Prince Orlov in St. Petersburg from 1883 to 1886. He began to study protists and received a doctorate in 1887 for his studies on ''Ceratium hirundinella''. He then spent some years as a private tutor in Germany in the Baron Belevski household. He then travelled ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Otto Friedrich Müller
Otto Friedrich Müller, also known as Otto Friedrich Mueller (2 November 1730 – 26 December 1784) was a Denmark, Danish natural history, naturalist and scientific illustrator. Biography Müller was born in Copenhagen. He was educated for the church, became tutor to a young nobleman, and after several years' travel with him, settled in Copenhagen in 1767, and married a lady of wealth. His first important works, ''Fauna Insectorum Friedrichsdaliana'' (Leipzig, 1764), and ''Flora Friedrichsdaliana'' (Strasbourg, 1767), giving accounts of the insects and flora of the estate of Frederiksdal House, Frederiksdal, near Copenhagen, recommended him to Frederick V of Denmark, by whom he was employed to continue the ''Flora Danica'' a comprehensive atlas of the flora of Denmark. Müller added two volumes to the three published by Georg Christian Oeder since 1761. The study of invertebrates began to occupy his attention almost exclusively, and in 1771 he produced a work in German on “Cer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organelle
In cell biology, an organelle is a specialized subunit, usually within a cell (biology), cell, that has a specific function. The name ''organelle'' comes from the idea that these structures are parts of cells, as Organ (anatomy), organs are to the Human body, body, hence ''organelle,'' the suffix ''-elle'' being a diminutive. Organelles are either separately enclosed within their own lipid bilayers (also called membrane-bounded organelles) or are spatially distinct functional units without a surrounding lipid bilayer (non-membrane bounded organelles). Although most organelles are functional units within cells, some functional units that extend outside of cells are often termed organelles, such as cilia, the flagellum and archaellum, and the trichocyst (these could be referred to as membrane bound in the sense that they are attached to (or bound to) the membrane). Organelles are identified by microscopy, and can also be purified by cell fractionation. There are many types of organe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mechanoreceptors
A mechanoreceptor, also called mechanoceptor, is a sensory receptor that responds to mechanical pressure or distortion. Mechanoreceptors are located on sensory neurons that convert mechanical pressure into electrical signals that, in animals, are sent to the central nervous system. Vertebrate mechanoreceptors Cutaneous mechanoreceptors Cutaneous mechanoreceptors respond to mechanical stimuli that result from physical interaction, including pressure and vibration. They are located in the skin, like other cutaneous receptors. They are all innervated by Aβ fibers, except the mechanorecepting free nerve endings, which are innervated by Aδ fibers. Cutaneous mechanoreceptors can be categorized by what kind of sensation they perceive, by the rate of adaptation, and by morphology. Furthermore, each has a different receptive field. By sensation * The Slowly Adapting type 1 (SA1) mechanoreceptor, with the Merkel corpuscle end-organ (also known as Merkel discs) detect sustaine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Remanella
''Remanella'' is a genus of karyorelict ciliates, belonging to family Loxodidae. Whereas ''Remanella'' inhabits brackish and marine waters, ''Loxodes'' – the other loxodid genus – is a freshwater taxon. Etymology The genus name is a patronym honoring the German zoologist Adolf Remane (1898–1976), who contributed to the discovery of the marine interstitial fauna. Phylogeny Molecular phylogeny based on sequences of the SSU rRNA gene suggests that the genus ''Remanella'' might be paraphyletic with respect to a monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ... genus ''Loxodes'' but this result is not strongly supported. Species list At least 18 species are recognized in the genus ''Remanella'': References External links * ' {{Taxonbar, from=Q2 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
