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BotIT2
BotIT2 is a neurotoxin from the scorpion ''Buthus occitanus tunetanus'', which modifies activation and slows down the deactivation of voltage gated sodium channels. Source and etymology BotIT2 is found in the venom of the scorpion ''Buthus occitanus tunetanus'' (Bot) and hence named Buthus occitanus tunetanus insect toxin 2 (BotIT2). Chemistry Structure The BotIT2 peptide is composed of 60 amino-acids (Fig. 1) and its C-terminal residue contains a free carboxyl group. The molecular mass of BotIT2 is 6919 Da. Family BotIT2 belongs to the Buthidae neurotoxin family. Three main groups are distinguishable in this family: the α-, the β- and the depressant toxins. The BotIT2 has characteristics of all these subgroups. However, BotIT2 is classified as a β-depressant toxin. Homology BotIT2 differs from other scorpion toxins not only in its amino acid sequence, but in its effects on activation kinetics of insect sodium channels as well. Similarities are found between Bot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neurotoxin
Neurotoxins are toxins that are destructive to nerve tissue (causing neurotoxicity). Neurotoxins are an extensive class of exogenous chemical neurological insultsSpencer 2000 that can adversely affect function in both developing and mature nervous tissue.Olney 2002 The term can also be used to classify endogenous compounds, which, when abnormally contacted, can prove neurologically toxic. Though neurotoxins are often neurologically destructive, their ability to specifically target neural components is important in the study of nervous systems. Common examples of neurotoxins include lead, ethanol (drinking alcohol), glutamate,Choi 1987 nitric oxide, botulinum toxin (e.g. Botox), tetanus toxin,Simpson 1986 and tetrodotoxin. Some substances such as nitric oxide and glutamate are in fact essential for proper function of the body and only exert neurotoxic effects at excessive concentrations. Neurotoxins inhibit neuron control over ion concentrations across the cell memb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Current Clamp
In electrical and electronic engineering, a current clamp, also known as current probe, is an electrical device with jaws which open to allow clamping around an electrical conductor. This allows measurement of the current in a conductor without the need to make physical contact with it, or to disconnect it for insertion through the probe. Current clamps are typically used to read the magnitude of alternating current (AC) and, with additional instrumentation, the phase and waveform can also be measured. Some clamp meters can measure currents of 1000 A and more. Hall effect and vane type clamps can also measure direct current (DC). Types of current clamp Current transformer A common form of current clamp comprises a split ring made of ferrite or soft iron. A wire coil is wound round one or both halves, forming one winding of a current transformer. The conductor it is clamped around forms the other winding. Like any transformer this type works only with AC or pulse waveform ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scorpion Toxin
Scorpion toxins are proteins found in the venom of scorpions. Their toxic effect may be mammal- or insect-specific and acts by binding with varying degrees of specificity to members of the Voltage-gated ion channel superfamily; specifically, voltage-gated sodium channels, voltage-gated potassium channels, and Transient Receptor Potential (TRP) channels. The result of this action is to activate or inhibit the action of these channels in the nervous and cardiac organ systems. For instance, α-scorpion toxins MeuNaTxα-12 and MeuNaTxα-13 from ''Mesobuthus eupeus'' are neurotoxins that target voltage-gated Na+ channels (Navs), inhibiting fast inactivation. ''In vivo'' assays of MeuNaTxα-12 and MeuNaTxα-13 effects on mammalian and insect Navs show differential potency. These recombinants (MeuNaTxα-12 and MeuNaTxα-13) exhibit their preferential affinity for mammalian and insect Na+ channels at the α-like toxins' active site, site 3, in order to inactivate the cell membrane depolari ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
German Cockroach
The German cockroach (''Blattella germanica''), colloquially known as the croton bug, is a species of small cockroach, typically about long. In color it varies from tan to almost black, and it has two dark, roughly parallel, streaks on the pronotum running anteroposteriorly from behind the head to the base of the wings. Although ''B. germanica'' has wings, it can barely fly, although it may glide when disturbed. Of the few species of cockroach that are domestic pests, it probably is the most widely troublesome example. It is very closely related to the Asian cockroach, and to the casual observer, the two appear nearly identical and may be mistaken for each other. However, the Asian cockroach is attracted to light and can fly like a moth, while the German cockroach cannot. Biology and pest status The German cockroach occurs widely in human buildings, but is particularly associated with restaurants, food processing facilities, hotels, and institutional establishments such as n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
LD50
In toxicology, the median lethal dose, LD50 (abbreviation for "lethal dose, 50%"), LC50 (lethal concentration, 50%) or LCt50 is a toxic unit that measures the lethal dose of a toxin, radiation, or pathogen. The value of LD50 for a substance is the Dose (pharmacology), dose required to kill half the members of a tested population after a specified test duration. LD50 figures are frequently used as a general indicator of a substance's acute toxicity. A lower LD50 is indicative of increased toxicity. The test was created by J.W. Trevan in 1927. The term semilethal dose is occasionally used in the same sense, in particular with translations of foreign language text, but can also refer to a sublethal dose. LD50 is usually determined by tests on animals such as Laboratory mouse, laboratory mice. In 2011, the U.S. Food and Drug Administration approved alternative methods to LD50 for testing the cosmetic drug Botox without animal tests. Conventions The LD50 is usually expressed as the m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toxicity
Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a substructure of the organism, such as a cell ( cytotoxicity) or an organ such as the liver (hepatotoxicity). By extension, the word may be metaphorically used to describe toxic effects on larger and more complex groups, such as the family unit or society at large. Sometimes the word is more or less synonymous with poisoning in everyday usage. A central concept of toxicology is that the effects of a toxicant are dose-dependent; even water can lead to water intoxication when taken in too high a dose, whereas for even a very toxic substance such as snake venom there is a dose below which there is no detectable toxic effect. Toxicity is species-specific, making cross-species analysis problematic. Newer paradigms and metrics are evolving to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Action Potential
An action potential occurs when the membrane potential of a specific cell location rapidly rises and falls. This depolarization then causes adjacent locations to similarly depolarize. Action potentials occur in several types of animal cells, called excitable cells, which include neurons, muscle cells, and in some plant cells. Certain endocrine cells such as pancreatic beta cells, and certain cells of the anterior pituitary gland are also excitable cells. In neurons, action potentials play a central role in cell-cell communication by providing for—or with regard to saltatory conduction, assisting—the propagation of signals along the neuron's axon toward synaptic boutons situated at the ends of an axon; these signals can then connect with other neurons at synapses, or to motor cells or glands. In other types of cells, their main function is to activate intracellular processes. In muscle cells, for example, an action potential is the first step in the chain of event ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Depolarization
In biology, depolarization or hypopolarization is a change within a cell, during which the cell undergoes a shift in electric charge distribution, resulting in less negative charge inside the cell compared to the outside. Depolarization is essential to the function of many cells, communication between cells, and the overall physiology of an organism. Most cells in higher organisms maintain an internal environment that is negatively charged relative to the cell's exterior. This difference in charge is called the cell's membrane potential. In the process of depolarization, the negative internal charge of the cell temporarily becomes more positive (less negative). This shift from a negative to a more positive membrane potential occurs during several processes, including an action potential. During an action potential, the depolarization is so large that the potential difference across the cell membrane briefly reverses polarity, with the inside of the cell becoming positively char ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gating (electrophysiology)
In electrophysiology, the term gating refers to the opening (activation) or closing (by deactivation or inactivation) of ion channels. This change in conformation is a response to changes in transmembrane voltage. When ion channels are in a 'closed' (non-conducting) state, they are impermeable to ions and do not conduct electrical current. When ion channels are in their open state, they conduct electrical current by allowing specific types of ions to pass through them, and thus, across the plasma membrane of the cell. Gating is the process by which an ion channel transitions between its open and closed states. A variety of cellular changes can trigger gating, depending on the ion channel, including changes in voltage across the cell membrane (voltage-gated ion channels), chemicals interacting with the ion channel (ligand-gated ion channels), changes in temperature, stretching or deformation of the cell membrane, addition of a phosphate group to the ion channel (phosphorylation), a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Voltage Clamp
The voltage clamp is an experimental method used by electrophysiologists to measure the ion currents through the membranes of excitable cells, such as neurons, while holding the membrane voltage at a set level. A basic voltage clamp will iteratively measure the membrane potential, and then change the membrane potential (voltage) to a desired value by adding the necessary current. This "clamps" the cell membrane at a desired constant voltage, allowing the voltage clamp to record what currents are delivered. Because the currents applied to the cell must be equal to (and opposite in charge to) the current going across the cell membrane at the set voltage, the recorded currents indicate how the cell reacts to changes in membrane potential. Cell membranes of excitable cells contain many different kinds of ion channels, some of which are voltage-gated. The voltage clamp allows the membrane voltage to be manipulated independently of the ionic currents, allowing the current–voltage ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Buthus Occitanus
''Buthus occitanus'', the common yellow scorpion, is a species of scorpion in the family Buthidae. It occurs in the Middle East, North Africa and Europe. ''B. occitanus'' is 60–80 mm in length, has a yellow or yellow-brown color and is venomous producing BotIT6 toxin, but its toxicity varies markedly across its range. This scorpion is often found in dry and hot areas with sparse vegetation, where it hides under stones etc. during daytime. It has also been reported from Mediterranean forests in Spain at altitudes above 1000 meters (with snowfall Snow comprises individual ice crystals that grow while suspended in the atmosphere—usually within clouds—and then fall, accumulating on the ground where they undergo further changes. It consists of frozen crystalline water throughout ... in the winter). The sting in Europe is painful but with only mild toxic effects, however, in Africa it can be fatal. References Buthidae Animals described in 1789 Scorpions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Cockroach
The american cockroach (''Periplaneta americana'') is the largest species of common cockroach, and often considered a pest. In certain regions of the U.S. it is colloquially known as the waterbug, though it is not a true waterbug since it is not aquatic. It is also known as the ship cockroach, kakerlac, and Bombay canary. It is often misidentified as a palmetto bug. Despite their name, American cockroaches are native to Africa and the Middle East. They are believed to have been introduced to the Americas only from the 17th century AD onward as a result of human commercial patterns, including the Atlantic slave trade. Distribution Despite the name, none of the ''Periplaneta'' species is native to the Americas; ''P. americana'' was introduced to what is now the United States from Africa as early as 1625. They are now common in tropical climates because human activity has extended the insects' range of habitation, and are virtually cosmopolitan in distribution as a result of g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
