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Juvenile Hormone
Juvenile hormones (JHs) are a group of acyclic sesquiterpenoids that regulate many aspects of insect physiology. The first discovery of a JH was by Vincent Wigglesworth. JHs regulate development, reproduction, diapause, and polyphenisms.The chemical formula for juvenile hormone is C_18H_30O_3. In insects, JH (formerly called neotenin) refers to a group of hormones, which ensure growth of the larva, while preventing metamorphosis. Because of their rigid exoskeleton, insects grow in their development by successively shedding their exoskeleton (a process known as molting). Juvenile hormones are secreted by a pair of endocrine glands behind the brain called the corpora allata. JHs are also important for the production of eggs in female insects. JH was isolated in 1965 by Karel Sláma and Carroll Williams and the first molecular structure of a JH was solved in 1967. Most insect species contain only juvenile growth hormone (JH) III. To date JH 0, JH I, and JH II have been identifi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sesquiterpenoid
Sesquiterpenes are a class of terpenes that consist of three isoprene units and often have the molecular formula C15H24. Like monoterpenes, sesquiterpenes may be cyclic or contain rings, including many unique combinations. Biochemical modifications such as oxidation or rearrangement produce the related sesquiterpenoids. Sesquiterpenes are found naturally in plants and insects, as semiochemicals, e.g. defensive agents or pheromones. Biosynthesis and examples The reaction of geranyl pyrophosphate with isopentenyl pyrophosphate results in the 15-carbon farnesyl pyrophosphate (FPP), which is an intermediate in the biosynthesis of sesquiterpenes such as farnesene. Cyclic sesquiterpenes are more common than cyclic monoterpenes because of the increased chain length and additional double bond in the sesquiterpene precursors. In addition to common six-membered ring systems such as the ones found in zingiberene and bisacurone, cyclization of one end of the chain to the other end can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diptera
Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advanced mechanosensory organs known as halteres, which act as high-speed sensors of rotational movement and allow dipterans to perform advanced aerobatics. Diptera is a large order containing an estimated 1,000,000 species including horse-flies, crane flies, hoverflies and others, although only about 125,000 species have been described. Flies have a mobile head, with a pair of large compound eyes, and mouthparts designed for piercing and sucking (mosquitoes, black flies and robber flies), or for lapping and sucking in the other groups. Their wing arrangement gives them great maneuverability in flight, and claws and pads on their feet enable them to cling to smooth surfaces. Flies undergo complete metamorphosis; the eggs are often laid on the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecdysone
Ecdysone is a prohormone of the major insect molting hormone 20-hydroxyecdysone, which is secreted from the prothoracic glands. It is of steroidal structure. Insect molting hormones (ecdysone and its homologues) are generally called ecdysteroids. Ecdysteroids act as moulting hormones of arthropods but also occur in other related phyla where they can play different roles. In ''Drosophila melanogaster'', an increase in ecdysone concentration induces the expression of genes coding for proteins that the larva requires, and it causes chromosome puffs (sites of high expression) to form in polytene chromosomes. Recent findings in the laboratory of Chris Q. Doe have found a novel role of this hormone in regulating temporal gene transitions within neural stem cells of the fruit fly. Ecdysone and other ecdysteroids also appear in many plants mostly as a protection agent ( toxins or antifeedants) against herbivorous insects. These phytoecdysteroids have been reputed to have medicinal va ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diminutive
A diminutive is a root word that has been modified to convey a slighter degree of its root meaning, either to convey the smallness of the object or quality named, or to convey a sense of intimacy or endearment. A ( abbreviated ) is a word-formation device used to express such meanings. In many languages, such forms can be translated as "little" and diminutives can also be formed as multi-word constructions such as " Tiny Tim". Diminutives are often employed as nicknames and pet names when speaking to small children and when expressing extreme tenderness and intimacy to an adult. The opposite of the diminutive form is the augmentative. Beyond the ''diminutive form'' of a single word, a ''diminutive'' can be a multi-word name, such as "Tiny Tim" or "Little Dorrit". In many languages, formation of diminutives by adding suffixes is a productive part of the language. For example, in Spanish can be a nickname for someone who is overweight, and by adding an suffix, it becomes wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhodnius
''Rhodnius'' is a genus of assassin bugs in the subfamily Triatominae (the kissing bugs), and is an important vector in the spread of Chagas disease. The ''Rhodnius'' species were important models for Sir Vincent Wigglesworth's studies of insect physiology, specifically growth and development. Species *''Rhodnius amazonicus'' Almeida, Santos & Sposina, 1973 *''Rhodnius brethesi'' Matta, 1919 (Tc) *''Rhodnius colombiensis'' Moreno Mejía, Galvão & Jurberg, 1999 *''Rhodnius dalessandroi'' Carcavallo & Barreto, 1976 *''Rhodnius domesticus'' Neiva & Pinto, 1923 (Tc) *''Rhodnius ecuadoriensis'' Lent & León, 1958 (Tc) *''Rhodnius milesi'' Carcavallo, Rocha, Galvão, Jurberg, 2001 *'' Rhodnius nasutus'' Stål, 1859 (Tc) *'' Rhodnius neglectus'' Lent, 1954 (Tc) *''Rhodnius neivai'' Lent, 1953 *'' Rhodnius pallescens'' Barber, 1932 (Tc) (principal vector in Panama). *''Rhodnius paraensis'' Sherlock, Guitton & Miles, 1977 (Tc) *''Rhodnius pictipes'' Stål, 1872 (Tc) *''Rhodnius prolixus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Instar
An instar (, from the Latin '' īnstar'', "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (''ecdysis''), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or assume a new form. Differences between instars can often be seen in altered body proportions, colors, patterns, changes in the number of body segments or head width. After shedding their exoskeleton (moulting), the juvenile arthropods continue in their life cycle until they either pupate or moult again. The instar period of growth is fixed; however, in some insects, like the salvinia stem-borer moth, the number of instars depends on early larval nutrition. Some arthropods can continue to moult after sexual maturity, but the stages between these subsequent moults are generally not called instars. For most insect species, an ''instar'' is the developmental stage of the larval forms of holometabolous (complete metamorphism) or nymphal fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecdysis
Ecdysis is the moulting of the cuticle in many invertebrates of the clade Ecdysozoa. Since the cuticle of these animals typically forms a largely inelastic exoskeleton, it is shed during growth and a new, larger covering is formed. The remnants of the old, empty exoskeleton are called exuviae. After moulting, an arthropod is described as ''teneral'', a ''callow''; it is "fresh", pale and soft-bodied. Within one or two hours, the cuticle hardens and darkens following a tanning process analogous to the production of leather. During this short phase the animal expands, since growth is otherwise constrained by the rigidity of the exoskeleton. Growth of the limbs and other parts normally covered by the hard exoskeleton is achieved by transfer of body fluids from soft parts before the new skin hardens. A spider with a small abdomen may be undernourished but more probably has recently undergone ecdysis. Some arthropods, especially large insects with tracheal respiration, expand the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Juvenile Hormone Epoxide Hydrolase
Juvenile hormone epoxide hydrolase (JHEH) is an enzyme that inactivates insect juvenile hormones. This inactivation is accomplished through hydrolysis of the epoxide functional group contained within these hormones into diols. JHEH is one of two enzymes involved in the termination of signaling properties of the various juvenile hormones. The other is juvenile-hormone esterase, or JHE. The first observation of activity from JHEH was in ''Rhodnius prolixus'' and ''Schistocerca gregaria''. JH esterase was also first observed in this same work. Mechanism JH esterase and epoxide hydrolase are the only known enzymes involved in primary degradation of JH. The inactivated carboxylic acid products of juvenile hormone esterase can be reactivated in peripheral tissues by esterification restoring its biological activity. In contrast, the juvenile hormone diols that are the product of the epoxide hydrolase are very hydrophilic and cannot be converted back to JH. Thus, this enzyme perma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haemolymph
Hemolymph, or haemolymph, is a fluid, analogous to the blood in vertebrates, that circulates in the interior of the arthropod (invertebrate) body, remaining in direct contact with the animal's tissues. It is composed of a fluid plasma in which hemolymph cells called hemocytes are suspended. In addition to hemocytes, the plasma also contains many chemicals. It is the major tissue type of the open circulatory system characteristic of arthropods (e.g. arachnids, crustaceans and insects). In addition, some non-arthropods such as molluscs possess a hemolymphatic circulatory system. Oxygen-transport systems were long thought unnecessary in insects, but ancestral and functional hemocyanin has been found in the hemolymph. Insect "blood" generally does not carry hemoglobin, although hemoglobin may be present in the tracheal system instead and play some role in respiration. Method of transport In the grasshopper, the closed portion of the system consists of tubular hearts and an aor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allatostatin
Allatostatins are neuropeptide hormones in insects and crustacea. They have a twofold function: they both inhibit the generation of juvenile hormone and reduce their food intake. They are therefore putative targets for insecticide research.{{cite journal , author=Gäde G, Goldsworthy GJ , title=Insect peptide hormones: a selective review of their physiology and potential application for pest control , journal=Pest Manag. Sci. , volume=59 , issue=10 , pages=1063–75 , year=2003 , pmid=14561063 , doi=10.1002/ps.755 Types Three biochemically distinct types of Allatostatin have been described: A, B and C. Although originally identified in different insects, all three types are found in the fruitfly, ''Drosophila''. These types of Allatostatin are not normally found in the same neurons, and so probably have different roles. Control of food intake Allatostatin is found in the cells in a small neuronal cluster, the frontal ganglion. It is also present in the axons which leave the fron ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
G-protein Coupled Receptor
G protein-coupled receptors (GPCRs), also known as seven-(pass)-transmembrane domain receptors, 7TM receptors, heptahelical receptors, serpentine receptors, and G protein-linked receptors (GPLR), form a large group of evolutionarily-related proteins that are cell surface receptors that detect molecules outside the cell and activate cellular responses. Coupling with G proteins, they are called seven-transmembrane receptors because they pass through the cell membrane seven times. Text was copied from this source, which is available under Attribution 2.5 Generic (CC BY 2.5) license. Ligands can bind either to extracellular N-terminus and loops (e.g. glutamate receptors) or to the binding site within transmembrane helices (Rhodopsin-like family). They are all activated by agonists although a spontaneous auto-activation of an empty receptor can also be observed. G protein-coupled receptors are found only in eukaryotes, including yeast, choanoflagellates, and an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conifer
Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All extant conifers are perennial woody plants with secondary growth. The great majority are trees, though a few are shrubs. Examples include cedars, Douglas-firs, cypresses, firs, junipers, kauri, larches, pines, hemlocks, redwoods, spruces, and yews.Campbell, Reece, "Phylum Coniferophyta". Biology. 7th. 2005. Print. P. 595 As of 1998, the division Pinophyta was estimated to contain eight families, 68 genera, and 629 living species. Although the total number of species is relatively small, conifers are ecologically important. They are the dominant plants over large areas of land, most notably the taiga of the Northern Hemisphere, but also in similar cool climates in mountains further south. Boreal conifers have many wintertime ada ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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