|
Epithemia Gibba
''Epithemia'' is a genus of diatoms belonging to the family Rhopalodiaceae. The genus has cosmopolitan distribution and are found in freshwater and marine ecosystems. Recent studies have proposed that the genus ''Rhopalodia'' should be recategorized to join ''Epithemia'' based on phylogenetic evidence, although this change in nomenclature has been disputed. Members of this genus have endosymbionts that fix nitrogen called spheroid bodies, that are derived from cyanobacteria. This endosymbiont is closely related to the nitroplast organelle. Because of this close relationship, ''Epithemia'' has been proposed as a model system to study the early stages of organelle evolution. Because of their nitrogen fixing endosymbionts, they can be a possible indicator of eutrophication, because ''Epithemia'' abundance decreased with increased ambient inorganic N concentrations. Species Those marked with a * were previously in the genus ''Rhopalodia.'' *''Epithemia adnata'' (Kützing) Bré ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diatom
A diatom (Neo-Latin ''diatoma'') is any member of a large group comprising several Genus, genera of algae, specifically microalgae, found in the oceans, waterways and soils of the world. Living diatoms make up a significant portion of Earth's Biomass (ecology), biomass. They generate about 20 to 50 percent of the oxygen produced on the planet each year, take in over 6.7 billion tonnes of silicon each year from the waters in which they live, and constitute nearly half of the organic material found in the oceans. The Protist shell, shells of dead diatoms are a significant component of marine sediment, and the entire Amazon basin is fertilized annually by 27 million tons of diatom shell dust transported by transatlantic winds from the African Sahara, much of it from the Bodélé Depression, which was once made up of a system of fresh-water lakes. Diatoms are unicellular organisms: they occur either as solitary cells or in Colony (biology), colonies, which can take the shape of ribb ... [...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] |
Phylogenetics
In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical data and observed heritable traits of DNA sequences, protein amino acid sequences, and morphology. The results are a phylogenetic tree—a diagram depicting the hypothetical relationships among the organisms, reflecting their inferred evolutionary history. The tips of a phylogenetic tree represent the observed entities, which can be living taxa or fossils. A phylogenetic diagram can be rooted or unrooted. A rooted tree diagram indicates the hypothetical common ancestor of the taxa represented on the tree. An unrooted tree diagram (a network) makes no assumption about directionality of character state transformation, and does not show the origin or "root" of the taxa in question. In addition to their use for inferring phylogenetic pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endosymbiont
An endosymbiont or endobiont is an organism that lives within the body or cells of another organism. Typically the two organisms are in a mutualism (biology), mutualistic relationship. Examples are nitrogen-fixing bacteria (called rhizobia), which live in the root nodules of legumes, single-cell algae inside Coral reef, reef-building corals, and bacterial endosymbionts that provide essential nutrients to insects. Endosymbiosis played key roles in the development of eukaryotes and plants. Roughly 2.2 billion years ago an archaeon absorbed a bacterium through phagocytosis, that eventually became the mitochondria that provide energy to almost all living Eukaryote, eukaryotic cells. Approximately 1 billion years ago, some of those cells absorbed cyanobacteria that eventually became chloroplasts, organelles that produce energy from sunlight. Approximately 100 million years ago, a lineage of amoeba in the genus ''Paulinella'' independently engulfed a cyanobacterium that evolved to be f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrogen Fixation
Nitrogen fixation is a chemical process by which molecular dinitrogen () is converted into ammonia (). It occurs both biologically and abiological nitrogen fixation, abiologically in chemical industry, chemical industries. Biological nitrogen fixation or ''diazotrophy'' is catalyzed by enzymes called nitrogenases. These enzyme complexes are encoded by the Nif gene, ''Nif'' genes (or ''Nif'' homologs) and contain iron, often with a second metal (usually molybdenum, but sometimes vanadium). Some nitrogen-fixing bacteria have symbiotic relationships with plants, especially legumes, mosses and aquatic ferns such as ''Azolla''. Looser non-symbiotic relationships between diazotrophs and plants are often referred to as associative, as seen in nitrogen fixation on rice roots. Nitrogen fixation occurs between some termites and fungus, fungi. It occurs naturally in the air by means of NOx, NOx production by lightning. Fixed nitrogen is essential to life on Earth. Organic compounds such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyanobacteria
Cyanobacteria ( ) are a group of autotrophic gram-negative bacteria that can obtain biological energy via oxygenic photosynthesis. The name "cyanobacteria" () refers to their bluish green (cyan) color, which forms the basis of cyanobacteria's informal common name, blue-green algae. Cyanobacteria are probably the most numerous taxon to have ever existed on Earth and the first organisms known to have produced oxygen, having appeared in the middle Archean eon and apparently originated in a freshwater or terrestrial environment. Their photopigments can absorb the red- and blue-spectrum frequencies of sunlight (thus reflecting a greenish color) to split water molecules into hydrogen ions and oxygen. The hydrogen ions are used to react with carbon dioxide to produce complex organic compounds such as carbohydrates (a process known as carbon fixation), and the oxygen is released as a byproduct. By continuously producing and releasing oxygen over billions of years, cyanobacte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitroplast
A nitroplast is an organelle found in certain species of algae, particularly in the marine algae ''Braarudosphaera bigelowii''. It plays a crucial role in nitrogen fixation, a process previously thought to be exclusive to bacteria and archaea. The discovery of nitroplasts has significant implications for both cellular biology and agricultural science. Discovery In 1998, Jonathan Zehr, an ocean ecologist at the University of California, Santa Cruz, and his colleagues found an unknown DNA sequence that appeared to be for an unknown nitrogen-fixing Cyanobacteria, cyanobacterium in the Pacific Ocean, which they called UCYN-A (unicellular cyanobacterial group A). At the same time, Kyoko Hagino, a paleontologist at Kōchi University, Kochi University, was working to culture the host organism, ''B. bigelowii''. The existence of nitroplasts was first proposed by researchers studying the interaction between ''B. bigelowii'' and UCYN-A in 2012. Initially, it was hypothesized that UCYN-A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Symbiogenesis
Symbiogenesis (endosymbiotic theory, or serial endosymbiotic theory) is the leading evolutionary theory of the origin of eukaryotic cells from prokaryotic organisms. The theory holds that mitochondria, plastids such as chloroplasts, and possibly other organelles of eukaryotic cells are descended from formerly free-living prokaryotes (more closely related to the Bacteria than to the Archaea) taken one inside the other in endosymbiosis. Mitochondria appear to be phylogenetically related to Rickettsiales bacteria, while chloroplasts are thought to be related to cyanobacteria. The idea that chloroplasts were originally independent organisms that merged into a symbiotic relationship with other one-celled organisms dates back to the 19th century, when it was espoused by researchers such as Andreas Schimper. The endosymbiotic theory was articulated in 1905 and 1910 by the Russian botanist Konstantin Mereschkowski, and advanced and substantiated with microbiological evidence by Lyn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epithemia Alpestris
''Epithemia'' is a genus of diatoms belonging to the family Rhopalodiaceae. The genus has cosmopolitan distribution and are found in freshwater and marine ecosystems. Recent studies have proposed that the genus ''Rhopalodia'' should be recategorized to join ''Epithemia'' based on phylogenetic evidence, although this change in nomenclature has been disputed. Members of this genus have endosymbionts that fix nitrogen called spheroid bodies, that are derived from cyanobacteria. This endosymbiont is closely related to the nitroplast organelle. Because of this close relationship, ''Epithemia'' has been proposed as a model system to study the early stages of organelle evolution. Because of their nitrogen fixing endosymbionts, they can be a possible indicator of eutrophication, because ''Epithemia'' abundance decreased with increased ambient inorganic N concentrations. Species Those marked with a * were previously in the genus ''Rhopalodia.'' *''Epithemia adnata'' (Kützing) Bré ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
