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Carl H. Johnson
Carl Hirschie Johnson is an American-born biologist who researches the chronobiology of different organisms, most notably the bacterial circadian rhythms of cyanobacteria.Johnson, C.H. "From Skepticism to Prominence: Circadian Clocks in Bacteria". Microbe 4(9). Sept, 2009 Johnson completed his undergraduate degree in Honors Liberal Arts at the University of Texas at Austin, and later earned his PhD in biology from Stanford University, where he began his research under the mentorship of Dr. Colin Pittendrigh."Carl Hirschie Johnson." ''Current Biology'', vol. 24, no. 3, 2014, pp. R100-R102. Currently, Johnson is the Stevenson Professor of Biological Sciences at Vanderbilt University."Department of Biological Sciences - Carl H. Johnson". Vanderbilt University. http://as.vanderbilt.edu/biosci/bio/carl-johnson. Accessed 29 Nov, 2016. Personal life Carl Johnson was born in Washington D.C. When he first began college at the University of Texas at Austin, he planned to go to medical sch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Washington, D
Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered on Washington, D.C. * George Washington (1732–1799), the first president of the United States Washington may also refer to: Places England * Washington, Tyne and Wear, a town in the City of Sunderland metropolitan borough ** Washington Old Hall, ancestral home of the family of George Washington * Washington, West Sussex, a village and civil parish Greenland * Cape Washington, Greenland * Washington Land Philippines *New Washington, Aklan, a municipality *Washington, a barangay in Catarman, Northern Samar *Washington, a barangay in Escalante, Negros Occidental *Washington, a barangay in San Jacinto, Masbate *Washington, a barangay in Surigao City United States * Washington, Wisconsin (other) * Fort Washington (other) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vertebrates
Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with currently about 69,963 species described. Vertebrates comprise such groups as the following: * jawless fish, which include hagfish and lampreys * jawed vertebrates, which include: ** cartilaginous fish (sharks, rays, and ratfish) ** bony vertebrates, which include: *** ray-fins (the majority of living bony fish) *** lobe-fins, which include: **** coelacanths and lungfish **** tetrapods (limbed vertebrates) Extant vertebrates range in size from the frog species ''Paedophryne amauensis'', at as little as , to the blue whale, at up to . Vertebrates make up less than five percent of all described animal species; the rest are invertebrates, which lack vertebral columns. The vertebrates traditionally include the hagfish, which do no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prokaryotes
A prokaryote () is a single-celled organism that lacks a nucleus and other membrane-bound organelles. The word ''prokaryote'' comes from the Greek πρό (, 'before') and κάρυον (, 'nut' or 'kernel').Campbell, N. "Biology:Concepts & Connections". Pearson Education. San Francisco: 2003. In the two-empire system arising from the work of Édouard Chatton, prokaryotes were classified within the empire Prokaryota. But in the three-domain system, based upon molecular analysis, prokaryotes are divided into two domains: ''Bacteria'' (formerly Eubacteria) and ''Archaea'' (formerly Archaebacteria). Organisms with nuclei are placed in a third domain, Eukaryota. In the study of the origins of life, prokaryotes are thought to have arisen before eukaryotes. Besides the absence of a nucleus, prokaryotes also lack mitochondria, or most of the other membrane-bound organelles that characterize the eukaryotic cell. It was once thought that prokaryotic cellular components within the cytopla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circadian Rhythms
A circadian rhythm (), or circadian cycle, is a natural, internal process that regulates the sleep–wake cycle and repeats roughly every 24 hours. It can refer to any process that originates within an organism (i.e., endogenous) and responds to the environment ( entrained by the environment). These 24-hour rhythms are driven by a circadian clock, and they have been widely observed in animals, plants, fungi and cyanobacteria. The term ''circadian'' comes from the Latin ''circa'', meaning "approximately", and ''dies'', meaning "day". Processes with 24-hour cycles are more generally called diurnal rhythms; diurnal rhythms should not be called circadian rhythms unless they can be confirmed as endogenous, and not environmental. Although circadian rhythms are endogenous, they are adjusted to the local environment by external cues called zeitgebers (German for "time givers"), which include light, temperature and redox cycles. In clinical settings, an abnormal circadian rhythm in humans ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synechococcus
''Synechococcus'' (from the Greek ''synechos'', in succession, and the Greek ''kokkos'', granule) is a unicellular cyanobacterium that is very widespread in the marine environment. Its size varies from 0.8 to 1.5 µm. The photosynthetic coccoid cells are preferentially found in well–lit surface waters where it can be very abundant (generally 1,000 to 200,000 cells per ml). Many freshwater species of ''Synechococcus'' have also been described. The genome of ''S. elongatus'' strain PCC7002 has a size of 3,008,047 bp, whereas the oceanic strain WH8102 has a genome of size 2.4 Mbp. Introduction ''Synechococcus'' is one of the most important components of the prokaryotic autotrophic picoplankton in the temperate to tropical oceans. The genus was first described in 1979, and was originally defined to include "small unicellular cyanobacteria with ovoid to cylindrical cells that reproduce by binary traverse fission in a single plane and lack sheaths". This definition ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Luciferase
Luciferase is a generic term for the class of oxidative enzymes that produce bioluminescence, and is usually distinguished from a photoprotein. The name was first used by Raphaël Dubois who invented the words ''luciferin'' and ''luciferase'', for the substrate and enzyme, respectively. Both words are derived from the Latin word ''lucifer'', meaning "lightbearer", which in turn is derived from the Latin words for "light" (''lux)'' and "to bring or carry" (''ferre)''.Luciferases are widely used in biotechnology, for bioluminescence imaging microscopy and as reporter genes, for many of the same applications as fluorescent proteins. However, unlike fluorescent proteins, luciferases do not require an external light source, but do require addition of luciferin, the consumable substrate. Examples A variety of organisms regulate their light production using different luciferases in a variety of light-emitting reactions. The majority of studied luciferases have been found in animals, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haloarchaea
Haloarchaea (halophilic archaea, halophilic archaebacteria, halobacteria) are a class of the Euryarchaeota, found in water saturated or nearly saturated with salt. Halobacteria are now recognized as archaea rather than bacteria and are one of the largest groups. The name 'halobacteria' was assigned to this group of organisms before the existence of the domain Archaea was realized, and while valid according to taxonomic rules, should be updated. Halophilic archaea are generally referred to as haloarchaea to distinguish them from halophilic bacteria. These microorganisms are among the halophile organisms, that they require high salt concentrations to grow, with most species requiring more than 2.0M NaCl for growth and survival. They are a distinct evolutionary branch of the Archaea distinguished by the possession of ether-linked lipids and the absence of murein in their cell walls. Haloarchaea can grow aerobically or anaerobically. Parts of the membranes of haloarchaea are purpli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chlamydomonas Reinhardtii
''Chlamydomonas reinhardtii'' is a single-cell green alga about 10 micrometres in diameter that swims with two flagella. It has a cell wall made of hydroxyproline-rich glycoproteins, a large cup-shaped chloroplast, a large pyrenoid, and an eyespot that senses light. '' Chlamydomonas'' species are widely distributed worldwide in soil and fresh water. ''Chlamydomonas reinhardtii'' is an especially well studied biological model organism, partly due to its ease of culturing and the ability to manipulate its genetics. When illuminated, ''C. reinhardtii'' can grow photoautotrophically, but it can also grow in the dark if supplied with organic carbon. Commercially, ''C. reinhardtii'' is of interest for producing biopharmaceuticals and biofuel, as well being a valuable research tool in making hydrogen. History The ''C. reinhardtii'' wild-type laboratory strain c137 (mt+) originates from an isolate collected near Amherst, Massachusetts, in 1945 by Gilbert M. Smith. The species' n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gonyaulax Polyedra
''Lingulodinium polyedra'' is a species of motile photosynthetic dinoflagellates. ''L. polyedra'' are often the cause of red tides in southern California, leading to bioluminescent displays on beaches at night. Life cycle As part of its life cycle, this species produces a resting stage, a dinoflagellate cyst called ''Lingulodinium machaerophorum'' (synonym ''Hystrichosphaeridium machaerophorum''). This cyst was first described by Deflandre and Cookson in 1955 from the Miocene of Balcombe Bay, Victoria, Australia as: "Shell globular, subsphaerical or ellipsoidal with a rigid membrane, more brittle than deformable, covered with numerous long, stiff, conical, pointed processes resembling the blade of a dagger. Surface of shell granular or punctate." Its stratigraphic range is the Upper Paleocene of eastern USA and Denmark till Recent. Organic-walled dinocyst morphology is shown to be controlled by changes in salinity and temperature in some species, more particularly process l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bioluminescent
Bioluminescence is the production and emission of light by living organisms. It is a form of chemiluminescence. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some Fungus, fungi, microorganisms including some bioluminescent bacteria, and terrestrial arthropods such as Firefly, fireflies. In some animals, the light is bacteriogenic, produced by symbiosis, symbiotic bacteria such as those from the genus ''Vibrio''; in others, it is autogenic, produced by the animals themselves. In a general sense, the principal chemical reaction in bioluminescence involves a light-emitting molecule and an enzyme, generally called luciferin and luciferase, respectively. Because these are generic names, luciferins and luciferases are often distinguished by the species or group, e.g. firefly luciferin. In all characterized cases, the enzyme Catalysis, catalyzes the Redox, oxidation of the luciferin. In some species, the luciferase requires other Cofactor (bio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fertilization
Fertilisation or fertilization (see spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give rise to a new individual organism or offspring and initiate its development. Processes such as insemination or pollination which happen before the fusion of gametes are also sometimes informally called fertilisation. The cycle of fertilisation and development of new individuals is called sexual reproduction. During double fertilisation in angiosperms the haploid male gamete combines with two haploid polar nuclei to form a triploid primary endosperm nucleus by the process of vegetative fertilisation. History In Antiquity, Aristotle conceived the formation of new individuals through fusion of male and female fluids, with form and function emerging gradually, in a mode called by him as epigenetic. In 1784, Spallanzani established the need of interaction between the female's ovum and male's sperm to form a zygote in frog ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Starfish
Starfish or sea stars are star-shaped echinoderms belonging to the class Asteroidea (). Common usage frequently finds these names being also applied to ophiuroids, which are correctly referred to as brittle stars or basket stars. Starfish are also known as asteroids due to being in the class Asteroidea. About 1,900 species of starfish live on the seabed in all the world's oceans, from warm, tropical zones to frigid, polar regions. They are found from the intertidal zone down to abyssal depths, at below the surface. Starfish are marine invertebrates. They typically have a central disc and usually five arms, though some species have a larger number of arms. The aboral or upper surface may be smooth, granular or spiny, and is covered with overlapping plates. Many species are brightly coloured in various shades of red or orange, while others are blue, grey or brown. Starfish have tube feet operated by a hydraulic system and a mouth at the centre of the oral or lower surface. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
