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Dictyocha Speculum
Dictyochales (Silicoflagellates, or Dictyochophyceae '' sensu stricto'') are a small group of unicellular heterokont algae, found in marine environments. Characteristics In one stage of their life cycle, they produce a siliceous skeleton, composed of a network of bars and spikes arranged to form an internal basket. These form a small component of marine sediments, and are known as microfossils from as far back as the early Cretaceous. Classification The algae in the Dictyochophyceae have been previously classified in the Chrysophyceae. There is one living genus, ''Dictyocha'', with two commonly recognised species. There are also several extinct genera, but their classification is difficult, since skeletons may show diverse forms within each living species. ''Dictyocha'' has one golden-brown chloroplast and a long flagellum extended into a wing-like shape. The skeleton-bearing stage is uninucleate, with many microtubule-supported projections, and there are also uninucle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dictyocha Speculum
Dictyochales (Silicoflagellates, or Dictyochophyceae '' sensu stricto'') are a small group of unicellular heterokont algae, found in marine environments. Characteristics In one stage of their life cycle, they produce a siliceous skeleton, composed of a network of bars and spikes arranged to form an internal basket. These form a small component of marine sediments, and are known as microfossils from as far back as the early Cretaceous. Classification The algae in the Dictyochophyceae have been previously classified in the Chrysophyceae. There is one living genus, ''Dictyocha'', with two commonly recognised species. There are also several extinct genera, but their classification is difficult, since skeletons may show diverse forms within each living species. ''Dictyocha'' has one golden-brown chloroplast and a long flagellum extended into a wing-like shape. The skeleton-bearing stage is uninucleate, with many microtubule-supported projections, and there are also uninucle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chloroplast
A chloroplast () is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it in the energy-storage molecules ATP and NADPH while freeing oxygen from water in the cells. The ATP and NADPH is then used to make organic molecules from carbon dioxide in a process known as 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 unicellular algae, up to 100 in plants like ''Arabidopsis'' and wheat. A chloroplast is characterized by its two membranes and a high concentration of chlorophyll. Other plastid types, such as the leucoplast and the chromoplast, contain little chlorophyll and do not carry out photosynthesis. Chloroplasts are highly dynamic—they circulat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zoologists
This is a list of notable zoologists who have published names of new taxa under the International Code of Zoological Nomenclature. A * Abe – Tokiharu Abe (1911–1996) * Abeille de Perrin, Ab. – Elzéar Abeille de Perrin (1843–1910) * Able – Kenneth W. Able (born 1945) * Abbott, C.C. Abbott – Charles Conrad Abbott (1843–1919) general zoology * C. Abbott – Charles Abbot (1761–1817) entomology * J. Abbott – John Abbot (1751–1841) entomology, ornithology * W. Abbott, Abbott – William Louis Abbott (1860–1936) mainly ornithology * Acerbi – Giuseppe Acerbi (1773–1846) * Acero – Arturo Acero Pizarro (born 1954) * Adams, Ad. – Charles Baker Adams (1814–1853) malacology * A. Adams – Arthur Adams (1820–1878) mostly marine animals * A.L. Adams – Andrew Leith Adams (1827–1882) vertebrate paleontology * D.B. Adams – Daniel B. Adams ( fl. 1979) paleontology * E. Adams – Edward Adams (1824–1856) * H. Adams – Henry Adams (1813–1877) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Botanists
This is a list of botanists who have Wikipedia articles, in alphabetical order by surname. The List of botanists by author abbreviation is mostly a list of plant taxonomists because an author receives a standard abbreviation only when that author originates a new plant name. Botany is one of the few sciences which can boast, since the Middle Ages, of a substantial participation by women. A *Erik Acharius *Julián Acuña Galé *Johann Friedrich Adam *Carl Adolph Agardh *Jacob Georg Agardh *Nikolaus Ager *William Aiton *Frédéric-Louis Allamand *Carlo Allioni *Prospero Alpini * Benjamin Alvord *Adeline Ames *Eliza Frances Andrews *Agnes Arber *Giovanni Arcangeli *David Ashton *William Guybon Atherstone *Anna Atkins * Daniel E. Atha *Armen Takhtajan B * Ernest Brown Babcock *Churchill Babington *Curt Backeberg *James Eustace Bagnall *Jacob Whitman Bailey *Liberty Hyde Bailey *Ibn al-Baitar *Giovanni Battista Balbis *John Hutton Balfour *Joseph Banks * César Barbosa * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Axodine
The axodines are a group of unicellular stramenopiles that includes silicoflagellate and rhizochromulinid algae, actinomonad heterotrophic flagellates and actinophryid heliozoa. Alternative classifications treat the dictyochophytes as heterokont algae, or as Chrysophyceae. Other overlapping taxonomic concepts include the Actinochrysophyceae, Actinochrysea or Dictyochophyceae ''sensu lato''. The grouping was proposed on the basis of ultrastructural similarities, and is consistent with subsequent molecular comparisons. The Axodine grouping was unusual in breaking with the traditions of botanical and protozoological taxonomy to include the actinophryid heliozoa as part of the lineage that also contained the pedinellid algae along with colorless relatives such as ''Actinomonas'', Pteridomonas, and ''Ciliophrys''; the axodines further included the silicoflagellates, and Rhizochromulinales. This followed a growing consensus that the actinophryid heliozoa were not related to other type ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uninucleate
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Microtubule
Microtubules are polymers of tubulin that form part of the cytoskeleton and provide structure and shape to eukaryotic cells. Microtubules can be as long as 50 micrometres, as wide as 23 to 27 nm and have an inner diameter between 11 and 15 nm. They are formed by the polymerization of a dimer of two globular proteins, alpha and beta tubulin into protofilaments that can then associate laterally to form a hollow tube, the microtubule. The most common form of a microtubule consists of 13 protofilaments in the tubular arrangement. Microtubules play an important role in a number of cellular processes. They are involved in maintaining the structure of the cell and, together with microfilaments and intermediate filaments, they form the cytoskeleton. They also make up the internal structure of cilia and flagella. They provide platforms for intracellular transport and are involved in a variety of cellular processes, including the movement of secretory vesicles, organell ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flagellum
A flagellum (; ) is a hairlike appendage that protrudes from certain plant and animal sperm cells, and from a wide range of microorganisms to provide motility. Many protists with flagella are termed as flagellates. A microorganism may have from one to many flagella. A gram-negative bacterium ''Helicobacter pylori'' for example uses its multiple flagella to propel itself through the mucus lining to reach the stomach epithelium, where it may cause a gastric ulcer to develop. In some 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 lash-like swimming motion. The flagellum in archaea is called the archaellum to note its difference from the bacterial flagellum. Eukaryotic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chrysophyceae
The Chrysophyceae, usually called chrysophytes, chrysomonads, golden-brown algae or golden algae are a large group of algae, found mostly in freshwater. Golden algae is also commonly used to refer to a single species, ''Prymnesium parvum'', which causes fish kills. The Chrysophyceae should not be confused with the Chrysophyta, which is a more ambiguous taxon. Although "chrysophytes" is the anglicization of "Chrysophyta", it generally refers to the Chrysophyceae. Members Originally they were taken to include all such forms of the diatoms and multicellular brown algae, but since then they have been divided into several different groups (e.g., Haptophyceae, Synurophyceae) based on pigmentation and cell structure. Some heterotrophic flagellates as the bicosoecids and choanoflagellates were sometimes seen as related to golden algae too. They are now usually restricted to a core group of closely related forms, distinguished primarily by the structure of the flagella in motile c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sensu Stricto
''Sensu'' is a Latin word meaning "in the sense of". It is used in a number of fields including biology, geology, linguistics, semiotics, and law. Commonly it refers to how strictly or loosely an expression is used in describing any particular concept, but it also appears in expressions that indicate the convention or context of the usage. Common qualifiers ''Sensu'' is the ablative case of the noun ''sensus'', here meaning "sense". It is often accompanied by an adjective (in the same case). Three such phrases are: *''sensu stricto'' – "in the strict sense", abbreviation ''s.s.'' or ''s.str.''; *''sensu lato'' – "in the broad sense", abbreviation ''s.l.''; *''sensu amplo'' – "in a relaxed, generous (or 'ample') sense", a similar meaning to ''sensu lato''. Søren Kierkegaard uses the phrase ''sensu eminenti'' to mean "in the pre-eminent r most important or significantsense". When appropriate, comparative and superlative adjectives may also be used to convey the meaning o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Early Cretaceous
The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma. Geology Proposals for the exact age of the Barremian-Aptian boundary ranged from 126 to 117 Ma until recently (as of 2019), but based on drillholes in Svalbard the defining early Aptian Oceanic Anoxic Event 1a (OAE1a) was carbon isotope dated to 123.1±0.3 Ma, limiting the possible range for the boundary to c. 122–121 Ma. There is a possible link between this anoxic event and a series of Early Cretaceous large igneous provinces (LIP). The Ontong Java-Manihiki-Hikurangi large igneous province, emplaced in the South Pacific at c. 120 Ma, is by far the largest LIP in Earth's history. The Ontong Java Plateau today covers an area of 1,860,000 km2. In the Indian Ocean another LIP began to form at c. 120 Ma, the Kerguelen P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
