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Autoinducer-2
Autoinducer-2 (AI-2) is a furanosyl borate diester or tetrahydroxy furan (species dependent) that—as the name suggests—is an autoinducer, a member of a family of signaling molecules used in quorum sensing. AI-2 is one of only a few known biomolecules incorporating boron. First identified in the marine bacterium '' Vibrio harveyi'', AI-2 is produced and recognized by many Gram-negative and Gram-positive bacteria. AI-2 arises by the reaction of 4,5-dihydroxy-2,3-pentanedione, which is produced enzymatically, with boric acid and is recognized by the two-component sensor kinase LuxPQ in Vibrionaceae. AI-2 is actively transported by the Lsr ABC-type transporter into the cell in Enterobacteriaceae and few other bacterial taxa such as ''Pasteurella'', ''Photorhabdus'', ''Haemophilus'', and ''Bacillus'', where it is phosphorylated by LsrK. Then, Phospho-AI-2 binds the transcriptional repressor protein, LsrR, which subsequently is released from the promoter/operator region of the ls ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vibrio Harveyi
''Vibrio harveyi'' is a Gram-negative, bioluminescent, marine bacterium in the genus ''Vibrio''. ''V. harveyi'' is rod-shaped, motile (via polar flagella), facultatively anaerobic, halophilic, and competent for both fermentative and respiratory metabolism. It does not grow below 4 °C ( optimum growth: 30° to 35 °C). ''V. harveyi'' can be found free-swimming in tropical marine waters, commensally in the gut microflora of marine animals, and as both a primary and opportunistic pathogen of marine animals, including Gorgonian corals, oysters, prawns, lobsters, the common snook, barramundi, turbot, milkfish, and seahorses. It is responsible for luminous vibriosis, a disease that affects commercially farmed penaeid prawns. Additionally, based on samples taken by ocean-going ships, ''V. harveyi'' is thought to be the cause of the milky seas effect, in which, during the night, a uniform blue glow is emitted from the seawater. Some glows can cover nearly . Quorum ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quorum Sensing
In biology, quorum sensing or quorum signaling (QS) is the process of cell-to-cell communication that allows bacteria to detect and respond to cell population density by gene regulation, typically as a means of acclimating to environmental disadvantages. Quorum sensing is a type of cellular signaling, and can be more specifically considered a type of paracrine signaling. However, it also contains traits of autocrine signaling: a cell produces both an autoinducer molecule and the receptor for the autoinducer. As one example, quorum sensing enables bacteria to restrict the expression of specific genes to the high cell densities at which the resulting phenotypes will be most beneficial, especially for phenotypes that would be ineffective at low cell densities and therefore too energetically costly to express. Many species of bacteria use quorum sensing to coordinate gene expression according to the density of their local population. In a similar fashion, some social insects use q ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
4,5-Dihydroxy-2,3-pentanedione
4,5-Dihydroxy-2,3-pentanedione (DPD) is an organic compound that occurs naturally but exists as several related structures. The idealized formula for this species is CH3C(O)C(O)CH(OH)CH2OH, but it is known to exist as several other forms resulting from cyclization. It is not stable at room temperature as a pure material, which has further complicated its analysis. The (''S'')-stereoisomer occurs naturally. It is typically hydrated, i.e., one keto group has added water to give the geminal diol. DPD is produced by degradation of S-Adenosyl-L-homocysteine, ''S''-adenosylhomocysteine by the action of the enzyme S-ribosylhomocysteine lyase, ''S''-ribosylhomocysteinase. The compound probably does not exist as depicted above, but as an equilibrium mixture of three hydrates. DPD reacts with boric acid to form a borate ester, borate diester known as autoinducer-2 (AI-2). AI-2 is a signaling molecule used for bacterial quorum sensing. It is produced and recognized by many Gram-nega ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tight Junction
Tight junctions, also known as occluding junctions or ''zonulae occludentes'' (singular, ''zonula occludens''), are multiprotein Cell junction, junctional complexes between epithelial cells, sealing and preventing leakage of solutes and water. They also play a critical role maintaining the structure and permeability of Endothelium, endothelial cells. Tight junctions may also serve as leaky pathways by forming selective channels for small cations, anions, or water. The corresponding junctions that occur in invertebrates are septate junctions. Structure Tight junctions are composed of a branching network of sealing strands, each strand acting independently from the others. Therefore, the efficiency of the junction in preventing ion passage increases exponentially with the number of strands. Each strand is formed from a row of transmembrane proteins embedded in both plasma membranes, with extracellular domains joining one another directly. There are at least 40 different proteins ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bacillus
''Bacillus'', from Latin "bacillus", meaning "little staff, wand", is a genus of Gram-positive, rod-shaped bacteria, a member of the phylum ''Bacillota'', with 266 named species. The term is also used to describe the shape (rod) of other so-shaped bacteria; and the plural ''Bacilli'' is the name of the class of bacteria to which this genus belongs. ''Bacillus'' species can be either obligate aerobes which are dependent on oxygen, or facultative anaerobes which can survive in the absence of oxygen. Cultured ''Bacillus'' species test positive for the enzyme catalase if oxygen has been used or is present. ''Bacillus'' can reduce themselves to oval endospores and can remain in this dormant state for years. The endospore of one species from Morocco is reported to have survived being heated to 420 °C. Endospore formation is usually triggered by a lack of nutrients: the bacterium divides within its cell wall, and one side then engulfs the other. They are not true spores (i.e. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Journal Of Bacteriology
A journal, from the Old French ''journal'' (meaning "daily"), may refer to: *Bullet journal, a method of personal organization *Diary, a record of personal secretive thoughts and as open book to personal therapy or used to feel connected to oneself. A record of what happened over the course of a day or other period *Daybook, also known as a general journal, a daily record of financial transactions *Logbook, a record of events important to the operation of a vehicle, facility, or otherwise * Transaction log, a chronological record of data processing * Travel journal, a record of the traveller's experience during the course of their journey In publishing, ''journal'' can refer to various periodicals or serials: *Academic journal, an academic or scholarly periodical **Scientific journal, an academic journal focusing on science ** Medical journal, an academic journal focusing on medicine **Law review, a professional journal focusing on legal interpretation *Magazine, non-academic or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
S-Adenosyl Methionine
''S''-Adenosyl methionine (SAM), also known under the commercial names of SAMe, SAM-e, or AdoMet, is a common cosubstrate involved in methyl group transfers, transsulfuration, and aminopropylation. Although these anabolic reactions occur throughout the body, most SAM is produced and consumed in the liver. More than 40 methyl transfers from SAM are known, to various substrates such as nucleic acids, proteins, lipids and secondary metabolites. It is made from adenosine triphosphate (ATP) and methionine by methionine adenosyltransferase. SAM was first discovered by Giulio Cantoni in 1952. In bacteria, SAM is bound by the SAM riboswitch, which regulates genes involved in methionine or cysteine biosynthesis. In eukaryotic cells, SAM serves as a regulator of a variety of processes including DNA, tRNA, and rRNA methylation; immune response; amino acid metabolism; transsulfuration; and more. In plants, SAM is crucial to the biosynthesis of ethylene, an important plant hormone ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Borate Ester
In organic chemistry, borate esters are organoboron compounds which are conveniently prepared by the stoichiometric condensation reaction of boric acid with alcohols. There are two main classes of borate esters: orthoborates, and metaborates, . Metaborates contain 6-membered boroxine rings. :B(OH)3 + 3 ROH -> B(OR)3 + 3 H2O :3 B(OH)3 + 3 ROH -> B3O3(OR)3 + 6 H2O A dehydrating agent, such as concentrated sulfuric acid is typically added. Borate esters are volatile and can be purified by distillation. This procedure is used for analysis of trace amounts of borate and for analysis of boron in steel. Like all boron compounds, alkyl borates burn with a characteristic green flame. This property is used to determine the presence of boron in qualitative analysis. Borate esters form spontaneously when treated with diols such as sugars and the reaction with mannitol forms the basis of a titrimetric analytical method for boric acid. Metaborate esters show considerable Lewis acidity ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mammal
A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three Evolution of mammalian auditory ossicles, middle ear bones. These characteristics distinguish them from reptiles and birds, from which their ancestors Genetic divergence, diverged in the Carboniferous Period over 300 million years ago. Around 6,640 Neontology#Extant taxon, extant species of mammals have been described and divided into 27 Order (biology), orders. The study of mammals is called mammalogy. The largest orders of mammals, by number of species, are the rodents, bats, and eulipotyphlans (including hedgehogs, Mole (animal), moles and shrews). The next three are the primates (including humans, monkeys and lemurs), the Artiodactyl, even-toed ungulates (including pigs, camels, and whales), and the Carnivora (including Felidae, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photorhabdus
''Photorhabdus'' is a genus of bioluminescent, gram-negative bacilli which lives symbiotically within entomopathogenic nematodes, hence the name ''photo'' (which means light producing) and ''rhabdus'' (rod shape). ''Photorhabdus'' is known to be pathogenic to a wide range of insects and has been used as biopesticide in agriculture. Life cycle ''Photorhabdus'' species facilitate the reproduction of entomopathogenic nematodes by infecting and killing susceptible insect larvae. Entomopathogenic nematodes are normally found in soil. Nematodes infect larval hosts by piercing the larval cuticle. When the nematode enters an insect larvae, ''Photorhabdus'' species are released by the nematodes and will produce a range of toxins, killing the host within 48 hours. ''Photorhabdus'' species feed on the cadaver of the insect and the process converts the cadaver into a nutrient source for the nematode. Mature nematodes leave the depleted body of the insect and search for new hosts to infect. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epithelium
Epithelium or epithelial tissue is a thin, continuous, protective layer of cells with little extracellular matrix. An example is the epidermis, the outermost layer of the skin. Epithelial ( mesothelial) tissues line the outer surfaces of many internal organs, the corresponding inner surfaces of body cavities, and the inner surfaces of blood vessels. Epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. These tissues also lack blood or lymph supply. The tissue is supplied by nerves. There are three principal shapes of epithelial cell: squamous (scaly), columnar, and cuboidal. These can be arranged in a singular layer of cells as simple epithelium, either simple squamous, simple columnar, or simple cuboidal, or in layers of two or more cells deep as stratified (layered), or ''compound'', either squamous, columnar or cuboidal. In some tissues, a layer of columnar cells may appear to be stratified d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
