Agatoxins: A class of polyamine and peptide toxins which are isolated from the venom of spiders such as Agelenopsis aperta.Conotoxins: Peptide neurotoxins from the marine fish-hunting snails of the genus CONUS. They contain 13 to 29 amino acids which are strongly basic and are highly cross-linked by disulfide bonds. There are three types of conotoxins, omega-, alpha-, and mu-. OMEGA-CONOTOXINS inhibit voltage-activated entry of calcium into the presynaptic membrane and therefore the release of ACETYLCHOLINE. Alpha-conotoxins inhibit the postsynaptic acetylcholine receptor. Mu-conotoxins prevent the generation of muscle action potentials. (From Concise Encyclopedia Biochemistry and Molecular Biology, 3rd ed)Conus Snail: A genus of cone-shaped marine snails in the family Conidae, class GASTROPODA. It comprises more than 600 species, many containing unique venoms (CONUS VENOMS) with which they immobilize their prey.Calcium Channels, N-Type: CALCIUM CHANNELS that are concentrated in neural tissue. Omega toxins inhibit the actions of these channels by altering their voltage dependence.Mollusk Venoms: Venoms from mollusks, including CONUS and OCTOPUS species. The venoms contain proteins, enzymes, choline derivatives, slow-reacting substances, and several characterized polypeptide toxins that affect the nervous system. Mollusk venoms include cephalotoxin, venerupin, maculotoxin, surugatoxin, conotoxins, and murexine.omega-Conotoxins: A family of structurally related neurotoxic peptides from mollusk venom that inhibit voltage-activated entry of calcium into the presynaptic membrane. They selectively inhibit N-, P-, and Q-type calcium channels.Biological Products: Complex pharmaceutical substances, preparations, or matter derived from organisms usually obtained by biological methods or assay.omega-Conotoxin GVIA: A neurotoxic peptide, which is a cleavage product (VIa) of the omega-Conotoxin precursor protein contained in venom from the marine snail, CONUS geographus. It is an antagonist of CALCIUM CHANNELS, N-TYPE.Hematologic Diseases: Disorders of the blood and blood forming tissues.Pulmonary Disease, Chronic Obstructive: A disease of chronic diffuse irreversible airflow obstruction. Subcategories of COPD include CHRONIC BRONCHITIS and PULMONARY EMPHYSEMA.Sleep Disorders: Conditions characterized by disturbances of usual sleep patterns or behaviors. Sleep disorders may be divided into three major categories: DYSSOMNIAS (i.e. disorders characterized by insomnia or hypersomnia), PARASOMNIAS (abnormal sleep behaviors), and sleep disorders secondary to medical or psychiatric disorders. (From Thorpy, Sleep Disorders Medicine, 1994, p187)Sleep: A readily reversible suspension of sensorimotor interaction with the environment, usually associated with recumbency and immobility.Heart: The hollow, muscular organ that maintains the circulation of the blood.Public Health: Branch of medicine concerned with the prevention and control of disease and disability, and the promotion of physical and mental health of the population on the international, national, state, or municipal level.Lung Diseases, Obstructive: Any disorder marked by obstruction of conducting airways of the lung. AIRWAY OBSTRUCTION may be acute, chronic, intermittent, or persistent.Calcium Channels: Voltage-dependent cell membrane glycoproteins selectively permeable to calcium ions. They are categorized as L-, T-, N-, P-, Q-, and R-types based on the activation and inactivation kinetics, ion specificity, and sensitivity to drugs and toxins. The L- and T-types are present throughout the cardiovascular and central nervous systems and the N-, P-, Q-, & R-types are located in neuronal tissue.Encyclopedias as Topic: Works containing information articles on subjects in every field of knowledge, usually arranged in alphabetical order, or a similar work limited to a special field or subject. (From The ALA Glossary of Library and Information Science, 1983)Calcium Channel Blockers: A class of drugs that act by selective inhibition of calcium influx through cellular membranes.Calcium Channels, L-Type: Long-lasting voltage-gated CALCIUM CHANNELS found in both excitable and nonexcitable tissue. They are responsible for normal myocardial and vascular smooth muscle contractility. Five subunits (alpha-1, alpha-2, beta, gamma, and delta) make up the L-type channel. The alpha-1 subunit is the binding site for calcium-based antagonists. Dihydropyridine-based calcium antagonists are used as markers for these binding sites.Ion Channels: Gated, ion-selective glycoproteins that traverse membranes. The stimulus for ION CHANNEL GATING can be due to a variety of stimuli such as LIGANDS, a TRANSMEMBRANE POTENTIAL DIFFERENCE, mechanical deformation or through INTRACELLULAR SIGNALING PEPTIDES AND PROTEINS.Ion Channel Gating: The opening and closing of ion channels due to a stimulus. The stimulus can be a change in membrane potential (voltage-gated), drugs or chemical transmitters (ligand-gated), or a mechanical deformation. Gating is thought to involve conformational changes of the ion channel which alters selective permeability.Pericytes: Unique slender cells with multiple processes extending along the capillary vessel axis and encircling the vascular wall, also called mural cells. Pericytes are imbedded in the BASEMENT MEMBRANE shared with the ENDOTHELIAL CELLS of the vessel. Pericytes are important in maintaining vessel integrity, angiogenesis, and vascular remodeling.Juxtaglomerular Apparatus: A complex of cells consisting of juxtaglomerular cells, extraglomerular mesangium lacis cells, the macula densa of the distal convoluted tubule, and granular epithelial peripolar cells. Juxtaglomerular cells are modified SMOOTH MUSCLE CELLS found in the walls of afferent glomerular arterioles and sometimes the efferent arterioles. Extraglomerular mesangium lacis cells are located in the angle between the afferent and efferent glomerular arterioles. Granular epithelial peripolar cells are located at the angle of reflection of the parietal to visceral angle of the renal corpuscle.Kidney Medulla: The internal portion of the kidney, consisting of striated conical masses, the renal pyramids, whose bases are adjacent to the cortex and whose apices form prominent papillae projecting into the lumen of the minor calyces.Kidney Concentrating Ability: The ability of the kidney to excrete in the urine high concentrations of solutes from the blood plasma.Arterioles: The smallest divisions of the arteries located between the muscular arteries and the capillaries.Patch-Clamp Techniques: An electrophysiologic technique for studying cells, cell membranes, and occasionally isolated organelles. All patch-clamp methods rely on a very high-resistance seal between a micropipette and a membrane; the seal is usually attained by gentle suction. The four most common variants include on-cell patch, inside-out patch, outside-out patch, and whole-cell clamp. Patch-clamp methods are commonly used to voltage clamp, that is control the voltage across the membrane and measure current flow, but current-clamp methods, in which the current is controlled and the voltage is measured, are also used.

N-type voltage-dependent calcium channels mediate the nicotinic enhancement of GABA release in chick brain. (1/34)

The role of voltage-dependent calcium channels (VDCCs) in the nicotinic acetylcholine receptor (nAChR)-mediated enhancement of spontaneous GABAergic inhibitory postsynaptic currents (IPSCs) was investigated in chick brain slices. Whole cell recordings of neurons in the lateral spiriform (SpL) and ventral lateral geniculate (LGNv) nuclei showed that cadmium chloride (CdCl2) blocked the carbachol-induced increase of spontaneous GABAergic IPSCs, indicating that VDCCs might be involved. To conclusively show a role for VDCCs, the presynaptic effect of carbachol on SpL and LGNv neurons was examined in the presence of selective blockers of VDCC subtypes. omega-Conotoxin GVIA, a selective antagonist of N-type channels, significantly reduced the nAChR-mediated enhancement of gamma-aminobutyric acid (GABA) release in the SpL by 78% compared with control responses. Nifedipine, an L-type channel blocker, and omega-Agatoxin-TK, a P/Q-type channel blocker, did not inhibit the enhancement of GABAergic IPSCs. In the LGNv, omega-Conotoxin GVIA also significantly reduced the nAChR-mediated enhancement of GABA release by 71% from control values. Although omega-Agatoxin-TK did not block the nicotinic enhancement, L-type channel blockers showed complex effects on the nAChR-mediated enhancement. These results indicate that the nAChR-mediated enhancement of spontaneous GABAergic IPSCs requires activation of N-type channels in both the SpL and LGNv.  (+info)

N-Type Ca(2+) channels trigger release of excitatory and inhibitory neurotransmitter from nerve endings in canine bronchi. (2/34)

We set out to characterize the types of Ca(2+) channels that mediate release of the predominant excitatory (acetylcholine) and inhibitory (norepinephrine) neurotransmitters in canine bronchi, using electrically evoked contractions and relaxations, respectively, as indicators of this release. We found that the selective N-type Ca(2+) channel blocker (omega-conotoxin GVIA) eliminated electrically evoked contractions in a dose-dependent fashion (half-maximal inhibition in the presence of 1-5 nM) but had no significant effect on those evoked by exogenously added acetylcholine. Selective blockers of P-type Ca(2+) channels (omega-agatoxin TK; 10(-8) to 10(-7) M) or of L-type Ca(2+) channels (nifedipine; 10(-8) to 10(-6) M) had no significant effect on the responses to neurally released or exogenously added acetylcholine. Likewise, electrically evoked relaxations were blocked by omega-conotoxin GVIA (10(-7) M) but not by omega-agatoxin TK (10(-7) M) or nifedipine (10(-7) M); none of these Ca(2+) channel blockers had a significant inhibitory effect on isoproterenol-triggered relaxations. We conclude that excitatory and inhibitory neurotransmission in canine bronchi is mediated predominantly by N-type Ca(2+) channels, with little or no contribution from L-, P-, Q-, or T-type channels.  (+info)

Role of glutamate receptors and voltage-dependent calcium channels in glutamate toxicity in energy-compromised cortical neurons. (3/34)

We have examined the effect of glutamate receptor antagonists and voltage-dependent calcium channel blockers on the neuronal injury induced by the combination of a low concentration of N-methyl-D-aspartate (NMDA) or kainate and energy compromise resulting from the use of glucose-free incubation buffer. Toxicity induced by NMDA or kainate was enhanced in the glucose-free buffer. NMDA-or non-NMDA-receptor antagonists added to the glucose-free buffer at the same time inhibited the neuronal cell death induced by each agonist. An NMDA-receptor antagonist, MK-801, but not non-NMDA-receptor antagonists, inhibited the toxicity when added to the culture medium after exposure of the cells to the agonists. P/Q-type calcium channel blockers, omega-agatoxin IVA and omega-agatoxin TK, and an N-type calcium channel blocker, omega-conotoxin GVIA, significantly attenuated the neuronal injury, although an L-type calcium channel blocker, nifedipine, showed little neuroprotective effect. A combination of calcium channel blockers of the three subtypes showed the most prominent neuroprotective effect. These observations suggest that the overactivation of NMDA and non-NMDA receptors and consequent activation of the voltage-dependent calcium channels lead to neuronal cell death in energy-compromised cortical neurons.  (+info)

The spider toxin omega-Aga IIIA defines a high affinity site on neuronal high voltage-activated calcium channels. (4/34)

The spider toxin omega-agatoxin IIIA (omega-Aga-IIIA) is a potent inhibitor of high voltage-activated calcium currents in the mammalian brain. To establish the biochemical parameters governing its action, we radiolabeled the toxin and examined its binding to native and recombinant calcium channels. In experiments with purified rat synaptosomal membranes, both kinetic and equilibrium data demonstrate one-to-one binding of omega-Aga-IIIA to a single population of high affinity sites, with K(d) = approximately 9 pm and B(max) = approximately 1.4 pmol/mg protein. Partial inhibition of omega-Aga-IIIA binding by omega-conotoxins GVIA, MVIIA, and MVIIC identifies N and P/Q channels as components of this population. omega-Aga-IIIA binds to recombinant alpha(1B) and alpha(1E) calcium channels with a similar high affinity (K(d) = approximately 5-9 pm) in apparent one-to-one fashion. Results from recombinant alpha(1B) binding experiments demonstrate virtually identical B(max) values for omega-Aga-IIIA and omega-conotoxin MVIIA, providing further evidence for a one-to-one stoichiometry of agatoxin binding to calcium channels. The combined evidence suggests that omega-Aga-IIIA defines a unique, high affinity binding site on N-, P/Q-, and R-type calcium channels.  (+info)

All classes of calcium channel couple with equal efficiency to exocytosis in rat melanotropes, inducing linear stimulus-secretion coupling. (5/34)

1. The contribution of low voltage-activated (LVA) T-type Ca2+ channels and four different types of high voltage-activated (HVA) Ca2+ channel to exocytosis, and the relationship between calcium influx and exocytosis during action potentials (APs) were studied in pituitary melanotropes. 2. Selective HVA Ca2+ channel blockers reduced exocytosis, monitored by membrane capacitance measurements, proportional to the reduction in Ca2+ influx. The efficacy of Ca2+ in stimulating exocytosis did not change in the presence of the Ca2+ channel blockers, indicating that all HVA Ca2+ channels act together in stimulating exocytosis. 3. The relationship between Ca2+ influx and exocytosis during the AP was examined using APs recorded from spontaneously active melanotropes as command templates under voltage clamp. Under voltage clamp, multiphasic Ca2+ currents were activated over the entire duration of the APs, i.e. during the rising phase as well as the plateau phase. The maximum amplitude of the Ca2+ current coincided with the peak of the AP. 4. The relationship between Ca2+ entry and exocytosis was linear for the different phases of the AP. Also, the influx of Ca2+ through LVA T-type channels stimulated exocytosis with the same efficacy as through the HVA channels. 5. APs of increasing duration ( approximately 50 to approximately 300 ms) evoked increasing amounts of exocytosis. The number of entering Ca2+ ions and the capacitance change were linearly related to AP duration, resulting in a fixed relationship between Ca2+ entry and exocytosis. 6. The results show that Ca2+ ions, entering a melanotrope, couple with equal strength to exocytosis regardless of the channel type involved. We suggest that the linear relationship between Ca2+ entry and secretion observed under physiological conditions (during APs), results from the equal strength with which LVA and HVA channels in melanotropes couple to exocytosis. This guarantees that secretion takes place over the entire duration of the AP.  (+info)

Dendro-somatic distribution of calcium-mediated electrogenesis in purkinje cells from rat cerebellar slice cultures. (6/34)

The role of Ca2+ entry in determining the electrical properties of cerebellar Purkinje cell (PC) dendrites and somata was investigated in cerebellar slice cultures. Immunohistofluorescence demonstrated the presence of at least three distinct types of Ca2+ channel proteins in PCs: the alpha1A subunit (P/Q type Ca2+ channel), the alpha1G subunit (T type) and the alpha1E subunit (R type). In PC dendrites, the response started in 66 % of cases with a slow depolarization (50 +/- 15 ms) triggering one or two fast (approximately 1 ms) action potentials (APs). The slow depolarization was identified as a low-threshold non-P/Q Ca2+ AP initiated, most probably, in the dendrites. In 16 % of cases, this response propagated to the soma to elicit an initial burst of fast APs. Somatic recordings revealed three modes of discharge. In mode 1, PCs display a single or a short burst of fast APs. In contrast, PCs fire repetitively in mode 2 and 3, with a sustained discharge of APs in mode 2, and bursts of APs in mode 3. Removal of external Ca2+ or bath applications of a membrane-permeable Ca2+ chelator abolished repetitive firing. Tetraethylammonium (TEA) prolonged dendritic and somatic fast APs by a depolarizing plateau sensitive to Cd2+ and to omega-conotoxin MVII C or omega-agatoxin TK. Therefore, the role of Ca2+ channels in determining somatic PC firing has been investigated. Cd2+ or P/Q type Ca2+ channel-specific toxins reduced the duration of the discharge and occasionallyinduced the appearance of oscillations in the membrane potential associated with bursts of APs. In summary, we demonstrate that Ca2+ entry through low-voltage gated Ca2+ channels, not yet identified, underlies a dendritic AP rarelyeliciting a somatic burst of APs whereas Ca2+ entry through P/Q type Ca2+ channels allowed a repetitive firing mainly by inducing a Ca2+-dependent hyperpolarization.  (+info)

Isolation, synthesis and pharmacological characterization of delta-palutoxins IT, novel insecticidal toxins from the spider Paracoelotes luctuosus (Amaurobiidae). (7/34)

Four novel insecticidal toxins were isolated from the venom of the spider Paracoelotes luctuosus (Araneae: Amaurobiidae) and named delta-palutoxins IT1 to IT4. The four toxins are homologous 36-37 amino acid peptides reticulated by four disulfide bridges and three have amidated C-terminal residues. The delta-palutoxins are highly homologous with the previously described mu-agatoxins and curtatoxins (77-97%). The four peptides demonstrated significant toxicity against larvae of the crop pest Spodoptera litura (Lepidoptera: Noctuidae) in a microinjection bioassay, with LD50 values in the 9-50 microg per g of insect range. This level of toxicity is equivalent to that of several of the most active scorpion toxins used in the development of recombinant baculoviruses, and the delta-palutoxins appear to be insect specific. Electrophysiological experiments demonstrated that delta-palutoxin IT1, the most active toxin acts by affecting insect sodium channel inactivation, resulting in the appearance of a late-maintained sodium current, in a similar fashion to insecticidal scorpion alpha and alpha-like toxins and is thus likely to bind to channel receptor site 3. However, delta-palutoxin IT1 was distinguished by its lack of effect on peak sodium conductance, on the early phase of sodium current inactivation and the absence of a shift in the activation voltage of the sodium channels. delta-Palutoxins are thus proposed as new insecticidal toxins related to the alpha and alpha-like scorpion toxins. They will be useful both in the development of recombinant baculoviruses in agrochemical applications and also as molecular probes for the investigation of molecular mechanisms of insect selectivity and structure and function of sodium channels.  (+info)

Oxytocin retrogradely inhibits evoked, but not miniature, EPSCs in the rat supraoptic nucleus: role of N- and P/Q-type calcium channels. (8/34)

We previously reported that oxytocin (OXT), released from the dendrites of magnocellular neurons in the supraoptic nucleus (SON), acts retrogradely on presynaptic terminals to inhibit glutamatergic transmission. Here we test the hypothesis that oxytocin reduces calcium influx into the presynaptic terminal. We used nystatin perforated-patch recording in vitro to first identify the calcium channels involved in glutamatergic transmission in the SON. [omega]-Conotoxin GVIA ([omega]-CTx) and [omega]-Agatoxin TK ([omega]-Aga) both reduced evoked EPSC amplitude, while nicardipine and nickel had no effect. A combination of [omega]-CTx and [omega]-Aga completely abolished the evoked EPSCs. This depressant effect was accompanied by an increase in the paired pulse ratio with no change in the kinetics of the evoked EPSCs, AMPA currents or postsynaptic cell properties. These results suggest that presynaptic N- and P/Q-type calcium channels mediate glutamate release in the SON while L-, T- and R-type channels make little or no contribution. Oxytocin-induced reduction of the evoked EPSC was substantially occluded in the presence of [omega]-CTx but only partially in the presence of [omega]-Aga. Amastatin, an endopeptidase inhibitor that increases the level of endogenous OXT, also reduced the evoked EPSC. This amastatin effect was also occluded by [omega]-CTx and [omega]-Aga. Miniature EPSCs, which are independent of extracellular calcium, were unaffected by either [omega]-CTx or by OXT, thus further substantiating an action of both compounds on calcium channels. Therefore, dendritically released oxytocin acts mainly via a mechanism involving the N-type channel, and to a lesser extent the P/Q-type channel, to decrease excitatory transmission.  (+info)

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My work is at the interface between behavior, ecology and evolutionary biology with a central focus on the extent to which populations are at adaptive equilibria with respect to their physical and biotic environments. These questions are pursued through genetic analyses of fitness-linked traits, through species optimum and game theoretic analyses and simulations, and through field manipulations and breeding experiments. Current work on the desert spider, Agelenopsis aperta, involves a quantitative genetic study of the effect of competitive interactions among conspecifics on the joint evolution of aggressiveness and body size. Aggressiveness is a social trait that is both a characteristic of an individual and of the environment. The results of a breeding experiment presented in Riechert and Johns (2005) suggested that while such factors as metabolic rate and assimilation efficiency are heritable, their effects on an individuals phenotype are overridden by behavioral aggressiveness which also is ...
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|p>Special Olympics is a global organization that serves athletes with intellectual disabilities working with hundreds of thousands of volunteers and coaches each year. Since the establishment of Special Olympics in 1968, the number of people with and without intellectual disabilities who are involved with the organization has been growing, but the unmet need to reach more people with intellectual disabilities is staggering.|/p>
Voltage-sensitive calcium channels (VSCC) mediate the entry of calcium ions into excitable cells and are also involved in a variety of calcium-dependent processes, including muscle contraction, hormone or neurotransmitter release, gene expression, cell motility, cell division and cell death. The isoform alpha-1C gives rise to L-type calcium currents. Long-lasting (L-type) calcium channels belong to the high-voltage activated (HVA) group. They are blocked by dihydropyridines (DHP), phenylalkylamines, benzothiazepines, and by omega-agatoxin-IIIA (omega-Aga-IIIA). They are however insensitive to omega-conotoxin-GVIA (omega-CTx-GVIA) and omega-agatoxin-IVA (omega-Aga-IVA). Calcium channels containing the alpha-1C subunit play an important role in excitation-contraction coupling in the heart. The various isoforms display marked differences in the sensitivity to DHP compounds. Binding of calmodulin or CABP1 at the same regulatory sites results in an opposit effects on the channel function ...
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A new peptide antagonist of voltage-activated calcium channels was purified from venom of the funnel web spider, Agelenopsis aperta. This 48-amino acid peptide, omega-agatoxin (omega-Aga)-IVB, was found to be a potent (Kd, approximately 3 nM) blocker of P-type calcium channels in rat cerebellar Purkinje neurons but had no activity against T-type, L-type, or N-type calcium channels in a variety of neurons. The calcium channel-blocking properties of omega-Aga-IVB were similar to those of another toxin, omega-Aga-IVA, which has 71% amino acid identity with omega-Aga-IVB. The 10-fold greater abundance of omega-Aga-IVB in venom allowed structural studies using NMR spectroscopy. The three-dimensional structure derived from NMR data resulted in a proposed disulfide bond configuration for the peptide. Although omega-Aga-IVB has fewer basic and more acidic residues than does omega-Aga-IVA, the two toxins show conservation of positively charged residues in a mid-peptide region that is predicted to form ...
The modulatory effect of D 2 dopamine receptor activation on calcium currents was studied in neostriatal projection neurons at two stages of rat development: postnatal day (PD)14 and PD40. D-2-class receptor agonists reduced whole cell calcium currents by about 35% at both stages, and this effect was blocked by the D-2 receptor antagonist sulpiride. Nitrendipine partially occluded this modulation at both stages, indicating that modulation of Ca(V)1 channels was present throughout this developmental interval. Nevertheless, modulation of Ca(V)1 channels was significantly larger in PD40 neurons. omega-Conotoxin GVIA occluded most of the Ca2+ current modulation in PD14 neurons. However, this occlusion was greatly decreased in PD40 neurons. omega-Agatoxin TK occluded a great part of the modulation in PD40 neurons but had a negligible effect in PD14 neurons. The data indicate that dopaminergic D-2-mediated modulation undergoes a change in target during development: from Ca(V)2.2 to Ca(V)2.1 Ca2+ ...
Ingredient in funnel web spider venom can protect cells from being destroyed by a stroke, even when given hours after the event, study shows The protective molecule was discovered by chance as researchers sequenced the DNA of toxins in the venom of Hadronyche infensa, the Darling Downs funnel web spider. Doctors have stumbled on an…
La vergogna della tratta raccontata dalla strada" del suo Medico al Ordinare Pillole di Marca Cozaar. Su questo sito utilizziamo strumenti nostri o piace dare dei consigli per vivere questo vecchia data Ordinare Pillole Di Marca Cozaar fare conoscenze nuove di. Se i Comuni e lo Stato pretendessero meno tasse (IMU), ci sarebbero più risorse ed eventuali tariffe per il contrassegno La arrivare allinizio del campionato, poi per mille in parte, vogliamo riportare alla memoria. Dopo essere stata curata per due anni tuoi gusti, preferenze e abitudini di consumo, fatto due "richiami" tranquillissimi a rispettare il nel 1903, Ordinare Pillole Di Marca Cozaar. Your browser will redirect to your requested. Quello che ti dico con certezza è quanto sia faticoso quel tipo di lavoro tempo allaria aperta (come può capitare agli e nei casi gravi, ricorrere ai farmaci. Sulla Statale 16, nel Foggiano, per cause mammiferi), organo muscolare, presente solo nelle femmine, S50 Quale Conviene Acquistare. Una ...
Voltage-sensitive calcium channels (VSCC) mediate the entry of calcium ions into excitable cells and are also involved in a variety of calcium-dependent processes, including muscle contraction, hormone or neurotransmitter release, gene expression, cell motility, cell division and cell death. The isoform alpha-1S gives rise to L-type calcium currents. Long-lasting (L-type) calcium channels belong to the high-voltage activated (HVA) group. They are blocked by dihydropyridines (DHP), phenylalkylamines, benzothiazepines, and by omega-agatoxin-IIIA (omega-Aga-IIIA). They are however insensitive to omega-conotoxin-GVIA (omega-CTx-GVIA) and omega-agatoxin-IVA (omega-Aga-IVA). Calcium channels containing the alpha-1S subunit play an important role in excitation-contraction coupling in skeletal muscle ...
Australian funnel-web spiders (family Hexathelidae, subfamily Atracinae, genera Atrax and Hadronyche) are among the most venomous spiders in the world based on clinical experience in Australia, although their importance to human health is limited by their confined geographic range. Funnel-web spiders belong to the suborder Mygalomorphae, a pr...
This is a throwback puzzle to the early days of Foldit. This small toxin is produced from the funnel-web spider A. aperta, and induces paralysis in insects by blocking calcium channels. This protein contains eight cysteines that oxidize to form four disulfide bonds. We are revisiting old Foldit puzzles so we can see how useful the recent additions to the game have been ...
Numerous spider toxins are of interest as tools for neurophysiological research or as lead molecules for the development of pharmaceuticals and insecticides. Direct detection and identification of the interacting proteins of a spider toxin are helpful for its action-mechanism analysis and practi...
[email protected] staff is a group of interracial international politically charged women who are educated in the fields of community studies, creative writing, critical dance theory and performance management, feminist studies, Latin American studies and sociology. They most sincerely love the various and extensive roles they play within the department and its community ...
The Infraorder Mygalomorphae is one of the three main lineages of spiders comprising over 3,000 nominal species. This ancient group has a world-wide distribution that includes among its ranks large and charismatic taxa such as tarantulas, trapdoor spiders, and highly venomous funnel web spiders. Based on past molecular studies using Sanger-sequencing approaches, numerous mygalomorph families (e.g., Hexathelidae, Ctenizidae, Cyrtaucheniidae, Dipluridae and Nemesiidae) have been identified as non-monophyletic. However, these data were unable to sufficiently resolve the higher-level (intra- and interfamilial) relationships such that the necessary changes in classification could be made with confidence. Here we present a comprehensive phylogenomic treatment of the spider infraorder Mygalomorphae. We employ 472 loci obtained through anchored hybrid enrichment to reconstruct relationships among all the mygalomorph spider families and estimate the timeframe of their diversification. We sampled nearly ...
The Infraorder Mygalomorphae is one of the three main lineages of spiders comprising over 3,000 nominal species. This ancient group has a world-wide distribution that includes among its ranks large and charismatic taxa such as tarantulas, trapdoor spiders, and highly venomous funnel web spiders. Based on past molecular studies using Sanger-sequencing approaches, numerous mygalomorph families (e.g., Hexathelidae, Ctenizidae, Cyrtaucheniidae, Dipluridae and Nemesiidae) have been identified as non-monophyletic. However, these data were unable to sufficiently resolve the higher-level (intra- and interfamilial) relationships such that the necessary changes in classification could be made with confidence. Here we present a comprehensive phylogenomic treatment of the spider infraorder Mygalomorphae. We employ 472 loci obtained through anchored hybrid enrichment to reconstruct relationships among all the mygalomorph spider families and estimate the timeframe of their diversification. We sampled nearly ...
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Il mondo dei profumi è già affascinante di per sé. Ma quando scopri tutto il lavoro che cè dietro per creare una fragranza, allora resti a bocca aperta. Quando MyFashionMagazine è[...] ...
Cose che non possono passare inosservate: il doodle di oggi - uno dei più semplici e modesti mai visti - è per il 14° compleanno di Google. Auguri a quello che più che un semplice motore di ricerca è una porta aperta dentro le nostre teste. Divertente la schermata qui sopra: nel 1997-98 Google era appena nato, era ancora ospite della Stanford University, usava il punto esclamativo in fondo copiando chiaramente Yahoo!, mandava una newsletter mensile (lol). E soprattutto aveva 25 milioni di pagine indicizzate e prometteva, a proposito del suo indice: "Soon to be much bigger". Fatto: nel 2008 il Google Blog ufficiale annunciava di aver superato "1 trillion (as in 1,000,000,000,000) unique URLs".. ...
Also called funnel web spiders, hobo spiders can be aggressive, though they infrequently attack humans unless provoked. The bite of a hobo spider can be very painful and the venom may result in necrosis of the surrounding tissue. Many reported cases of brown recluse bites are, in actuality, hobo spider bites. In cases where a bite results in necrosis, the severity is typically less than that associated with the bite of a brown recluse though the wound may take several weeks or months to heal. The hobo spider is typically found in the northwest region of the country though it is said to have originated from Europe.. ...
A new generation of environmentally safe insecticides that only target disease-carrying insects or those that damage crops is emerging from surprising research into the venom of one of the worlds deadliest creatures - the Australian Blue Mountains funnel-web spider.. The spiders potentially fatal effect on humans is an unlucky side-effect of just one of the 200 or so compounds its venom contains. But Dr Glenn King, professor of Biochemistry and Microbiology at the University of Connecticut Health Centre in the U.S. has said that many of the other compounds kill particular insects and are otherwise harmless.. This means the spiders venom has great potential to be developed as insecticides and could be used in two ways; as conventional sprayed pesticides, or delivered by insect-specific viruses that have been genetically engineered to contain a spider-venom gene.. "The latter approach is actually better from an environmental point of view because it is like a magic bullet that targets a ...
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... belongs to toxin group of Agatoxins. The amino acid structure of agelenin is Gly-Gly-Cys-Leu-Pro-His-Asn-Arg-Phe-Cys- ...
... aperta, the American funnel-web spider, produces agatoxins. Their bite causes rapid paralysis in insect prey, ...
"Structure-activity relationships for P-type calcium channel-selective omega-agatoxins". Nat. Struct. Biol. 1 (12): 853-6. doi: ...
The disulfide bonding pattern found in δ-Palutoxins is very similar to the pattern seen in µ-Agatoxins. This indicates strong ... homologies with the µ-Agatoxins from Agelenopsis aperta. Voltage-gated sodium channels have neurotoxin binding sites on their α ...
Agatoxins may be divided into three major structural subclasses: Alpha-agatoxins are composed of polyamines which are attached ... Agatoxins are a class of chemically diverse polyamine and peptide toxins which are isolated from the venom of various spiders. ... In several of the omega-agatoxins contain one or more D-amino acids which are produced from L-amino acids through the action of ... Omega-agatoxins in turn are subdivided in four classes based on their primary structures, biochemical properties and calcium ...
... the closely related P/Q-type channel blocked by ω-agatoxins, and the dihydropyridine-sensitive L-type channels responsible for ...
TY - JOUR. T1 - Voltage-gated divalent currents in descending vasa recta pericytes. AU - Zhang, Zhong. AU - Lin, Hai. AU - Cao, Chunhua. AU - Khurana, Sandeep. AU - Pallone, Thomas L.. PY - 2010/10/1. Y1 - 2010/10/1. N2 - Multiple voltage-gated Ca2+ channel (CaV) subtypes have been reported to participate in control of the juxtamedullary glomerular arterioles of the kidney. Using the patch-clamp technique, we examined whole cell CaV currents of pericytes that contract descending vasa recta (DVR). The dihydropyridine CaV agonist FPL64176 (FPL) stimulated inward Ca2+ and Ba2+ currents that activated with threshold depolarizations to -40 mV and maximized between -20 and -10 mV. These currents were blocked by nifedipine (1 μM) and Ni2+ (100 and 1,000 μM), exhibited slow inactivation, and conducted Ba2+ , Ca 2+ at a ratio of 2.3:1, consistent with "long-lasting" L-type CaV. In FPL, with 1 mM Ca2+ as charge carrier, Boltzmann fits yielded half-maximal activation potential (V1/2) and slope factors of ...
Agelenin belongs to toxin group of Agatoxins. The amino acid structure of agelenin is Gly-Gly-Cys-Leu-Pro-His-Asn-Arg-Phe-Cys- ...
Agelenopsis aperta, the American funnel-web spider, produces agatoxins. Their bite causes rapid paralysis in insect prey, ...
1994) Calcium channel diversity and neurotransmitter release: the omega-conotoxins and omega-agatoxins. Annu Rev Biochem 63:823 ...
The ω-Conotoxins and the ω-Agatoxins. Ann. Rev. Biochem 1994, 63, 823-867. [Google Scholar] ...
... the omega-conotoxins and omega-agatoxins. Annu. Rev. Biochem. 63: 823-67.PubMedCrossRefGoogle Scholar ...
The w-agatoxins, also isolated from the funnel web spider, comprise four subtypes. Most of these toxins block only N channels ( ...
Agatoxins: Ion channel specific toxins from the American funnel web spider, Agelenopsis aperta. Toxicon. 2004; 43: 509-525. ...
omega-Agatoxins: Novel calcium channel antagonists of two subtypes from funnel web spider (Agelenopsis aperta) venom. J. Biol. ... Adams, M.E. (2004) Agatoxins. Toxicon 43: 509-525. Kim, Y., Spalovska-Valachova, I., Cho, K., Zitnanova, I., Park, Y., Adams, M ... 1992 Antagonism of synaptosomal calcium channels by subtypes of omega-agatoxins. J. Biol. Chem. 267:2610-2615. Mintz, I.M., V.J ... Calcium channel diversity and neurotransmitter release: The w-conotoxins and w-agatoxins. Ann. Rev. Biochem. 63:823-867. Adams ...
Agatoxins are a polyamine and peptide toxins which differ from each other chemically. They are obtained from the venom of ... The agatoxins can be further divided into 3 subclasses, namely, alpha-agatoxin, omega-agatoxin and Mu-agatoxin. Alpha-agatoxin ...
... the closely related P/Q-type channel blocked by ω-agatoxins, and the dihydropyridine-sensitive L-type channels responsible for ...
Spiders: agatoxins - which block calcium channels and atracotoxins which cause uncontrollable opening of sodium channels are ...
Fingerprint Fingerprint is based on mining the text of the experts scientific documents to create an index of weighted terms, which defines the key subjects of each individual researcher. ...
... the closely related P/Q-type channel blocked by ω-agatoxins, and the dihydropyridine-sensitive L-type channels responsible for ...
Calhoun, J. D., Lambert, N. A., Mitalipova, M. M., Noggle, S. A., Lyons, I., Condie, B. G. & Stice, S. L., Jun 20 2003, In : Biochemical and Biophysical Research Communications. 306, 1, p. 191-197 7 p.. Research output: Contribution to journal › Article ...
Malee, K., Williams, P. L., Montepiedra, G., Nichols, S., Sirois, P. A., Storm, D., Farley, J., Kammerer, B., Turcich, M., Harris, L., Iovino, I., Usitalo, A., Rathore, M. H., Mirza, A., Mahmoudi, S., Malee, K., Cruz, C., Scalley, N., Khadivi, A., Miranda, D. & 171 others, Scott, G. B., Mitchell, C. D., Taybo, L., Willumsen, S., Adubato, S., Hanna, J., Sirois, P., Nichols, S., Wilson, S., Shaw, R., Grant, M. L., Chen, J. S., Foster, J. A., McQuiston, S., Homans, J., Neely, M., Spencer, L. S., Kovacs, A., Kammerer, B., Meade, J., Rothermel, R., Schuster, L., Yumoto, C., Miles, M., Cooper, T., Garvie, P., Borkowsky, W., Chandwani, S., Deygoo, N., Akleh, S., Bewley, S., Rohwedder, B., Mellins, C., Silverman, N., Jeremy, R., McEvoy, R., Hutton, N., Griffith, B., Joyner, M., Kiefner, C., Acker, M., Croteau, R., McLellan, C., Mohan, K., Breiger, D., Bamji, M., Pathak, I., Manwani, S., Patel, E., Abreu, E., Glass, P., New, M., Marshall, D., Lyon, M., Lee, S., Bowden, M., Ackerson, J., Marullo, D., ...
TY - JOUR. T1 - Neuropeptide Y (18-36) modulates chromaffin cell catecholamine secretion by blocking the nicotinic receptor ion channel. AU - Zheng, J.. AU - Morrisett, R. A.. AU - Zhu, J.. AU - Hexum, T. D.. PY - 1995. Y1 - 1995. N2 - Neuropeptide Y (NPY) is a widely distributed peptide with varied activities including inhibition of [3H]NE secretion from chromaffin cells. In the present study, we investigated the mechanism through which NPY and NPY fragments inhibit nicotinic receptor induced influx of 22Na+ and 45Ca++ into bovine chromaffin cells. Fragments of NPY, including NPY13- 36, NPY18-36 and NPY26-36, are more potent inhibitors of 45Ca++ and 22Na+ influx than NPY. High [K+]- and BAY K 8644-induced 45Ca++ influx and veratridine-induced 22Na+ influx are not inhibited by either NPY or NPY fragments. Thus, the site of NPY or NPY fragment action is not voltage-gated Ca++ or Na+ channels. A significant amount of acetylcholine- induced 45Ca++ influx still occurs in the presence of the ...
TY - JOUR. T1 - Possible modulatory role of voltage-activated Ca2+ currents determining the membrane properties of isolated pyramidal neurones of the rat dorsal cochlear nucleus. AU - Harasztosi, Csaba. AU - Forsythe, Ian D.. AU - Szûcs, Géza. AU - Stanfield, Peter R.. AU - Rusznák, Zoltán. PY - 1999/8/21. Y1 - 1999/8/21. N2 - Voltage-activated Ca2+ currents have been studied in pyramidal cells isolated enzymatically from the dorsal cochlear nuclei of 6-11-day-old Wistar rats, using whole-cell voltage-clamp. From hyperpolarized membrane potentials, the neurones exhibited a T-type Ca2+ current on depolarizations positive to -90 mV (the maximum occurred at about -40 mV). The magnitude of the T-current varied considerably from cell to cell (-56 to -852 pA) while its steady-state inactivation was consistent (E50 = -88.2 ± 1.7 mV, s = - 6.0 ± 0.4 mV). The maximum of high-voltage activated (HVA) Ca2+ currents was observed at about -15 mV. At a membrane potential of -10 mV the L-type Ca2+ channel ...
Agatoxins Medicine & Life Sciences * Conotoxins Medicine & Life Sciences * Calcium Channels Medicine & Life Sciences ...
The alpha-agatoxins and omega-agatoxins modify both insect and vertebrate ion channels, while the micro-agatoxins are selective ... Agatoxins: ion channel specific toxins from the American funnel web spider, Agelenopsis aperta. Agatoxins from Agelenopsis ... Agatoxins have been used as selective pharmacological probes for characterization of ion channels in the brain and heart, and ... 2004) Agatoxins: ion channel specific toxins from the American funnel web spider, Agelenopsis aperta. Toxicon. PMID: 15066410 ...
2004) Agatoxins: ion channel specific toxins from the american funnel web spider, Agelenopsis aperta. Toxicon. 43: 509-525. ...
... after which agatoxins are named. mu-Agatoxins are C-terminally amidated peptides that consist of 35-37 amino acids and are ... Agatoxins are a class of chemically diverse polyamine and peptide toxins which are isolated from the venom of various spiders, ... Agatoxins are a class of chemically diverse polyamine and peptide toxins which are isolated from the venom of various spiders, ... mu-Agatoxins modify presynaptic voltage-activated sodium channels in the neuromuscular joints of insects. Modifying sodium ...
The primary structure showed partial homology with that of mu-agatoxins from the funnel-web spider Agelenopsis aperta. ...
... the omega-conotoxins and omega-agatoxins. Annu Rev Biochem 1994, 63: 823-867. 10.1146/annurev.bi.63.070194.004135PubMedGoogle ...
Agatoxins D12.776.92.249 D12.776.93.249 Age Determination by Teeth E1.370.600.24.650.500 E5.41.650.500 E6.623.500 AIDS ...
  • Agelenopsis aperta, the American funnel-web spider, produces agatoxins. (wikipedia.org)
  • Agatoxins are a class of chemically diverse polyamine and peptide toxins which are isolated from the venom of various spiders, in particular the North American funnel-web spider (Agelenopsis aperta), after which agatoxins are named. (t3db.ca)
  • The alpha-agatoxins are non-competitive, use-dependent antagonists of glutamate receptor channels, and produce rapid but reversible paralysis in insect prey. (smartox-biotech.com)