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PubMed2005

Chemoarchitecture and afferent connections of the "olfactostriatum": a specialized vomeronasal structure within the basal ganglia of snakes.

The olfactostriatum, a portion of the striatal complex of snakes, is the major tertiary vomeronasal structure in the ophidian brain, receiving substantial afferents from the nucleus sphericus, the primary target of accessory olfactory bulb efferents. In the present study, we have characterized the olfactostriatum of garter snakes (Thamnophis sirtalis) on the basis of chemoarchitecture (distribution of serotonin, neuropeptide Y and tyrosine hydroxylase) and hodology (afferent connections). The olfactostriatum is densely immunoreactive for serotonin and neuropeptide Y and shows moderate-to-weak immunoreactivity for tyrosine hydroxylase. In addition to afferents from the nucleus sphericus, the olfactostriatum receives inputs from the dorsal and lateral cortices, nucleus of the accessory olfactory tract, external and dorsolateral amygdalae, dorsomedial thalamic nucleus, ventral tegmental area and raphe nuclei. Double labeling experiments demonstrated that the distribution of serotonin and neuropeptide Y in this area almost completely overlaps the terminal field of projections from the nucleus sphericus. Also, serotonergic and dopaminergic innervation of the olfactostriatum likely arise, respectively, from the raphe nuclei and the ventral tegmental area, whereas local circuit neurons originate the neuropeptide Y immunoreactivity. These results indicate that the olfactostriatum of snakes could be a portion of the nucleus accumbens, with features characteristic of the accumbens shell, devoted to processing vomeronasal information. Comparative data suggest that a similar structure is present in the ventral striatum of amphibians and mammals.

Afferent Pathways↗
PubMed2005

Efferent connections of the "olfactostriatum": a specialized vomeronasal structure within the basal ganglia of snakes.

The olfactostriatum is a portion of the basal ganglia of snakes that receives substantial vomeronasal afferents through projections from the nucleus sphericus. In a preceding article, the olfactostriatum of garter snakes (Thamnophis sirtalis) was characterized on the basis of chemoarchitecture (distribution of serotonin, neuropeptide Y and tyrosine hydroxylase) and pattern of afferent connections [Martinez-Marcos, A., Ubeda-Banon, I., Lanuza, E., Halpern, M., 2005. Chemoarchitecture and afferent connections of the "olfactostriatum": a specialized vomeronasal structure within the basal ganglia of snakes. J. Chem. Neuroanat. 29, 49-69]. In the present study, its efferent connections have been investigated. The olfactostriatum projects to the main and accessory olfactory bulbs, lateral cortex, septal complex, ventral pallidum, external, ventral anterior and dorsolateral amygdalae, bed nucleus of the stria terminalis, preoptic area, lateral posterior hypothalamic nucleus, ventral tegmental area, substantia nigra and raphe nuclei. Tracer injections in the nucleus accumbens proper, a structure closely associated with the olfactostriatum, result in a similar pattern of efferent connections with the exception of those reaching the main and accessory olfactory bulbs, lateral cortex, external, ventral anterior and dorsolateral amygdalae and bed nucleus of the stria terminalis. These data, therefore, help to characterize the olfactostriatum, an apparently specialized area of the nucleus accumbens. Double labeling experiments after tracer injections in the nucleus sphericus and the lateral posterior hypothalamic nucleus demonstrate a pathway between these two structures through the olfactostriatum. Injections in the olfactostriatum and in the medial amygdala show parallel projections to the lateral posterior hypothalamic nucleus. Since this hypothalamic nucleus has been previously described as projecting to the hypoglossal nucleus, both, the medial amygdala and the olfactostriatum may mediate vomeronasal influence on tongue-flick behavior.

Amygdala↗
PubMed2005

Purification and characterization of a hemorrhagic metalloproteinase from Bothrops lanceolatus (Fer-de-lance) snake venom.

Bothrops snake venoms contain metalloproteinases that contribute to the local effects seen after envenoming. In this work, a hemorrhagic metalloproteinase (BlaH1) was purified from the venom of the snake Bothrops lanceolatus by a combination of gel filtration, affinity (metal chelating) and hydrophobic interaction chromatographies. The hemorrhagin was homogeneous by SDS-PAGE and had a molecular mass of 28 kDa that was unaltered by treatment with beta-mercaptoethanol. BlaH1 gave a single band in immunoelectrophoresis and immunoblotting using commercial bothropic antivenom. BlaH1 had hemorrhagic, caseinolytic, fibrinogenolytic, collagenolytic and elastinolytic activities, but no phospholipase A(2) activity. The hemorrhagic and caseinolytic activities were inhibited by EDTA, indicating that they were metal ion-dependent. In contrast, aprotinin, benzamidine and PMSF did not affect these activities. The caseinolytic activity of BlaH1 had a pH optimum of 8.0 and was stable in solution at up to 40 degrees C; activity was completely lost at > or =70 degrees C. The hemorrhagic activity was neutralized by commercial bothropic antivenom. These properties suggest that this new hemorrhagin belongs to class P-I snake venom metalloproteinases.

Animals↗
PubMed2005

Presynaptic neuromuscular activity of venom from the brown-headed snake (Glyphodon tristis).

The brown-headed snake (Glyphodon tristis) inhabits the forest regions of Papua New Guinea, Torres Strait Islands, and far northern Queensland, Australia. Although bites by Glyphodon dunmalli have been reported, G. tristis was regarded as innocuous until 1989 when a healthy 20 year old man was bitten (Sutherland, S.K., Tibballs, J., 2001. Australian Animal Toxins, the Creatures, their Toxins and Care of the Poisoned Patient. University Press, Oxford). Treatment of envenomation by this species is empirical with no specific antivenom available. While no published studies on the venom of G. tristis are available, unpublished studies suggest neurotoxicity as being the main symptom of envenomation. In this study, the in vitro effects of G. tristis venom were examined using the chick biventer cervicis nerve muscle (CBCNM) preparation. Venom (10 microg/ml) inhibited indirect (0.2 ms, 0.1 Hz, supramaximal V) twitches of the CBCNM. This inhibition appeared to be presynaptic in origin as evidenced by the lack of effect of venom on responses to exogenous acetylcholine (1 mM), carbachol (20 microM) and KCl (40 mM) in the non-stimulated CBCNM. Prior addition (10 min) of polyvalent snake antivenom (5 U/ml; CSL Ltd) attenuated twitch inhibition. The venom (10-50 microg/ml) also appears to be myotoxic as indicated by a slowly developing contracture and inhibition of direct (2 ms, 0.1 Hz, supramaximal V, in the presence of tubocurarine 10 microM) twitches. Myotoxicity was confirmed by subsequent histological examination of tissues. This myotoxicity was prevented by the prior addition of polyvalent snake antivenom (30 U/ml). The phospholipase A inhibitor 4-BPB (1.8 mM) significantly attenuated the inhibition of indirect and direct twitches of the CBCNM preparation, indicating the involvement of a PLA2 component in the toxic action of the venom.

Animals↗
PubMed2005

Sex-based individual variation of snake venom proteome among eighteen Bothrops jararaca siblings.

Variation of venom proteome is relevant to basic research, to management of envenoming, and to studies on the evolution of poisonous snakes. In this study, we explored the venom proteomes of eighteen Bothrops jararaca specimens of a single litter born and raised in laboratory. Using electrophoretic techniques and various protocols for measuring the proteolytic activities of these venoms we have detected individual variability and highlighted sex-specific proteomic similarities and differences among sibling snakes. SDS-polyacrylamide gel electrophoresis under non-reducing conditions showed protein bands of approximately 100 kDa specific of male venoms. 2D-electrophoresis showed regions with varying spot complexity between pooled female and male venoms as well as spots that were gender specific. Gelatin zymography showed that female venoms contained proteinases of approximately 25 kDa absent from male venoms. Female venoms were more active than male venoms in degrading fibrinogen whereas on fibrin no significant differences were detected. Among various chromogenic peptide substrates tested, male venoms showed higher amidolytic activity than female venoms on D-Val-Leu-Lys-pNA and D-Phe-Pip-Arg-pNA. Taken together, these results show sex-based differences in the venom proteome of sibling snakes of a single litter raised under controlled conditions which seem to be genetically inherited and imposed by evolutionary forces.

Amides↗
PubMed2006

Galanin-like immunoreactivity in the brain of the snake Bothrops jararaca.

The distribution of galanin-like immunoreactive perikarya and nerve fibers in the brain of the snake Bothrops jararaca was studied by means of immunohistochemistry using an antiserum against porcine galanin. Immunoreactive neurons were only detected in the infundibular recess nucleus. Immunoreactive fibers were found in the telencephalic, diencephalic and mesencephalic areas such as the dorsal cortex, nucleus accumbens, lamina terminalis, preoptic area, mediodorsal region of the supraoptic nucleus, subfornical organ, nucleus of the paraventricular organ, subcommisural organ and periventricular grey region. The habenula, paraventricular nucleus, infundibular recess nucleus and hypothalamo-hypophyseal tract presented denser innervations. The outer layer of the median eminence displayed numerous fibers located close to the portal system, while scarce fibers were seen in the inner median eminence and neural lobe of the hypophysis. The distribution of labelled neurons in the brain of this snake was more restricted than that described in a turtle. The wide hypothalamic and extrahypothalamic distribution of labelled fibers suggests that galanin peptides may have hypophysiotropic, neuromodulator and neurotransmitter roles in the snake B. jararaca.

Animals↗
PubMed2002

Molecular cloning and characterization of protein phosphatase 2C of vomeronasal sensory epithelium of garter snakes.

The earthworm-derived chemoattractant ES20 interacts with its G-protein-coupled receptors on the plasma membrane of vomeronasal (VN) sensory neurons of garter snakes, resulting in an increase in inositol trisphosphate [J. Biol. Chem. 269 (1994) 16867] and a rapid phosphorylation of the membrane-bound proteins, p42/44 [Biochim. Biophys. Acta 1450 (1999) 320]. The phosphorylation of p42/44 proteins are countervailingly regulated by a protein kinase and an okadaic acid-insensitive but fluoride-sensitive protein phosphatase (PPase) [J. Liu et al. (loc. cit.)]. The phosphorylation of p42/44 induced by ES20 appears to play a role in the regulation of signal transduction pathways by modulating the GTPase activity [J. Liu et al. (loc. cit.)]. A 564-bp fragment of cDNA was obtained from VN RNA of garter snakes by reverse transcription polymerase chain reaction with degenerate primers. The 564-bp fragment was amplified, cloned, and sequenced. Northern blot analysis revealed that both the VN organ (VNO) and brain contained the gene of PPase 2C. A full-length complementary 4119-bp DNA containing an open reading frame of 1146bp that encodes a protein of 382 amino acids with a molecular mass of 49,123Da was obtained from the VN cDNA library of garter snakes. The deduced amino acid sequence showed 88% amino acid identity to bovine protein phosphatase 2C alpha and 87% identity to human and rat PP2C alpha and to Mg(2+)-dependent protein phosphatase 1A of rat and rabbit. In situ hybridization revealed that the mRNA of VN protein phosphatase 2C is expressed in the vomeronasal sensory epithelium. This is the first report of the identification of a type 2C serine/threonine protein phosphatase in the VN system.

Amino Acid Sequence↗
PubMed2002

Biochemical and biological properties of phospholipases A(2) from Bothrops atrox snake venom.

Phospholipases A(2) (PLA(2)s), of molecular mass 13-15kDa, are commonly isolated from snake venom. Two myotoxins with PLA(2) activity, BaPLA(2)I and BaPLA(2)III, with estimated molecular masses of 15kDa were isolated from the venom of Bothrops atrox using Sephacryl S-100-HR and reverse-phase chromatography. BaPLA(2)I was basic, with a pI of 9.1, while BaPLA(2)III was neutral with a pI of 6.9. On a molecular basis, BaPLA(2)III exhibited higher catalytic activity on synthetic substrates than BaPLA(2)I. Comparison of the N-terminal residues of BaPLA(2)I with other PLA(2) proteins from snake venoms showed that it has the highest homology (94%) with B. asper myotoxin II and homology with a PLA(2) Lys(49) from B. atrox (89%). In contrast, BaPLA(2)III demonstrated 75, 72, and 71% homology with PLA(2) from Vipera ammodytes meridionalis, B. jararacussu, and B. jararaca, respectively. BaPLA(2)I and BaPLA(2)III were capable, in vitro, of inducing mast cell degranulation and, in vivo, of causing creatine kinase release, edema, and myonecrosis typical of PLA(2)s from snake venoms, characterized by rapid disruption of the plasma membrane as indicated by clumping of myofilaments and necrosis of affected skeletal muscle cells. BaPLA(2)I- and BaPLA(2)III-specific monoclonal and polyclonal antibodies, although incapable of neutralizing PLA(2) edematogenic activity, blocked myonecrosis efficiently in an in vivo neutralization assay. The results presented herein suggest that the biological active site responsible for edema induction by these two PLA(2) enzymes is distinct from the myonecrosis active site and is not dependent upon the catalytic activity of the PLA(2) enzyme.

Amino Acid Sequence↗
PubMed2003

Inhibitory effect of fucoidan on the activities of crotaline snake venom myotoxic phospholipases A(2).

Myotoxic phospholipases A(2) account for most of the muscle necrosis that results from envenenomation by crotaline snakes. In this study, we investigated the protective effect of fucoidan, a natural sulfated polysaccharide obtained from the brown seaweed Fucus vesiculosus, against the cytotoxic and myotoxic activities of a group of phospholipase A(2) myotoxins from crotaline snake venoms: Bothrops asper myotoxins I, II, III, and IV, Cerrophidion godmani myotoxins I and II, Atropoides nummifer myotoxins I and II, and Bothriechis schlegelii myotoxin I. All of the toxins tested were efficiently inhibited by fucoidan, in both their cytotoxic and myotoxic effects. The basis for this inhibition appears to be the rapid formation of complexes between fucoidan and myotoxins, as evidenced by turbidimetric analysis. The possible binding site of fucoidan on the myotoxins was investigated using short synthetic peptides that represent the membrane-damaging region (residues 115-129) for three of these toxins. Fucoidan clearly inhibited the cytolytic activity of the peptides, indicating its ability to interact with the C-terminal myotoxic region of these phospholipases A(2). Fucoidan significantly inhibited muscle damage in mice, when administered locally, immediately after experimental envenomation with crude venom from B. asper. These results encourage further studies of sulfated fucans as compounds of potential use to improve the treatment of envenomations by crotaline snakes.

Animals↗
PubMed1999

Nanoscale design of snake skin for reptation locomotions via friction anisotropy.

Multi-mode scanning probe microscopy is employed to investigate the nanostructure of dermal samples from three types of snakes. Sophisticated friction modifying nanostructures are described. These include an ordered microfibrillar array that can function to achieve mission adaptable friction characteristics. Significant reduction of adhesive forces in the contact areas caused by the 'double-ridge' nanoscale microfibrillar geometry provides ideal conditions for sliding in forward direction with minimum adhesive forces and friction. Low surface adhesion in these local contact points may reduce local wear and skin contamination by environmental debris. The highly asymmetric, 'pawl-like' profile of the microfibrillar ends with radius of curvature 20-40 nm induces friction anisotropy in forward backward motions and serves as an effective stopper for backward motion preserving low friction for forward motion. The system of continuous micropores penetrating through the snake skin may serve as a delivery system for lubrication/anti-adhesive lipid mixture that provides for boundary lubrication of snake skins.

Actin Cytoskeleton↗
PubMed2001

Airway ammonia negates the normal ventilatory response to airway CO(2) in garter snakes.

Earlier studies from this lab showed that unidirectionally ventilated snakes, maintained on high airway [CO(2)], breathe slowly with a large tidal volume. If airway [CO(2)] is abruptly reduced during inspiration, inspiratory duration (TI) and tidal volume increase. On the other hand, in an animal normally receiving fresh air (no CO(2) in the inspired air) on each inspiration, if fresh air is withheld for one breath, TI and tidal volume decrease. To test the effect of producing an alkaline environment in the presence of CO(2) during these two maneuvers, six unidirectionally ventilated snakes weighing 32+/-16 g were maintained on 4% CO(2) in air flowing at 300 ml/min even during inspiration. NH(3) (4%) was introduced into the lung during one inspiration. During that breath, TI increased significantly, as if CO(2) had been removed from the lung. In another study, six different snakes weighing 21+/-6 g received fresh air at each inspiration. At the end of inspiration [CO(2)] was again raised to 4%. However, for one breath, [CO(2)] was maintained high during inspiration and airway NH(3) (3--4%) was simultaneously introduced into the airstream. During this breath, TI was expected to decrease, owing to the elevated [CO(2)]; however, there was no significant difference in the TI of the test breath compared with the previous breath, indicating that ammonia interfered with the expected CO(2) response. This study suggests that pH (probably intracellular) rather than P(CO(2)) produces this ventilatory reflex.

Administration, Inhalation↗
PubMed2001

Cross reactivity of different specific Micrurus antivenom sera with homologous and heterologous snake venoms.

Coral snakes are the only Elapids in America. They are represented by three genera: Leptomicrurus, Micruroides and Micrurus, of which the latter are the most abundant and diversified group. Little is known about the biochemistry of Micrurus venoms due to low availability. Here, we present a study on the cross reactivity of different specific Micrurus antivenom with homologous and heterologous snake venoms in order to contribute to the generation of more efficient antiserum for therapeutic purposes. The three specific antisera tested, anti-Micrurus corallinus, anti-Micrurus frontalis, and anti-Micrurus spixii, as well as the bivalent anti-elapid venom sera, raised against a mixture (50% each) of Micrurus frontalis and Micrurus corallinus venoms, were assayed by Western Blot against Micrurus and non-Micrurus elapid venoms. An antisera raised against a recombinant alpha-neurotoxin-like protein from Micrurus corallinus venom, only reacted in Western blot with its homologous venom, indicating that this protein is specific for Micrurus corallinus coral snake.

Animals↗
PubMed2002

Cysteine proteinase inhibitors in elapid and hydrophiid snake venoms.

The ability of elapid and hydrophiid snake venoms to inhibit cathepsin L was tested. All nine species of elapid and three species of hydrophiid snake venoms tested showed inhibition against cathepsin L. All of these venoms tested also showed inhibition against papain as well as against cathepsin L. Among these venoms, two elapid (Laticauda semifasciata venom, and Ophiophagus hannah venom) and one hydrophiid snake venom (Notechis scutatus scutatus venom) showed strong inhibition against both cathepsin L and papain. These venoms contained 12.0-13.0 kDa low molecular-weight cysteine proteinase inhibitors.

Animals↗
PubMed2003

Use of microarrays for investigating the subtoxic effects of snake venoms: insights into venom-induced apoptosis in human umbilical vein endothelial cells.

The pathological effects of only a small percentage of the total number of protein components of snake venoms are well documented, yet this knowledge has led to a general understanding of the physiological consequences of snake venom poisoning. The aim of this study was to assess the effect of subpathological levels of Crotalus atrox (Western diamondback rattlesnake) and Bothrops jararaca (Jararaca) snake venoms on the gene expression profile of human umbilical vein endothelial cells (HUVEC) in culture. Analysis of the data demonstrated that HUVECs treated with C. atrox venom had 33 genes up-regulated with significant fold changes of 1.5 or greater compared to untreated control cells. Ten genes were down-regulated with 1.5 or greater fold changes. In cells treated with B. jararaca venom, 33 genes were observed to be up-regulated and 11 genes were down-regulated with a fold change of 1.5 or more. More than half of the up-regulated genes and approximately half of the down-regulated genes detected in cells treated with the venoms were found in both data sets underscoring both the similarities and differences between the two venoms. Ontological categorization of the up-regulated genes from endothelial cells treated with either C. atrox or B. jararaca venom gave the cell growth/maintenance and signal transducer groups as having the most members. The ontology of the down-regulated genes from both venom-treated cell samples was more varied but interestingly, the predominant ontology class was also cell growth/maintenance. Many of the up-regulated genes are involved in the Fas ligand/TNF-alpha receptor apoptotic pathway. In summary, these experiments demonstrate the power of gene expression profiling to explore the subtoxic effects of venoms on gene expression and highlight its potential for the discovery of novel insights into a variety of biological processes and signal transduction pathways. Furthermore, these studies illustrate the subtle functional differences between similar venoms that are not always evident from standard analyses.

Animals↗
PubMed2003

Cloning and characterization of a basic phospholipase A2 homologue from Micrurus corallinus (coral snake) venom gland.

During the cloning of abundant cDNAs expressed in the Micrurus corallinus coral snake venom gland, several putative toxins, including a phospholipase A2 homologue cDNA (clone V2), were identified. The V2 cDNA clone codes for a potential coral snake toxin with a signal peptide of 27 amino acid residues plus a predicted mature protein with 119 amino acid residues. The deduced protein is highly similar to known phospholipases A2, with seven deduced S-S bridges at the same conserved positions. This protein was expressed in Escherichia coli as a His-tagged protein that allowed the rapid purification of the recombinant protein. This protein was used to generate antibodies, which recognized the recombinant protein in Western blot. This antiserum was used to screen a large number of venoms, showing a ubiquitous distribution of immunorelated proteins in all elapidic venoms but not in the viperidic Bothrops jararaca venom. This is the first description of a complete primary structure of a phospholipase A2 homologue deduced by cDNA cloning from a coral snake.

Amino Acid Sequence↗
PubMed2003

Characterization of nerve growth factors (NGFs) from snake venoms by use of a novel, quantitative bioassay utilizing pheochromocytoma (PC12) cells overexpressing human trkA receptors.

Snake venoms are a very abundant source of nerve growth factors (NGF). NGFs of Elapidae showing 65% sequence homology with mouse or human NGF, while the Viperidae NGF shows N-glycosylation (Asn-21) typical of these mammalian NGFs. Snake NGF-induced neurite outgrowth (neurotropic activity) was measured in the past by using PC12 cell or dorsal root ganglion bioassays. The present study was aimed at comparing, by dose-response experiments, the neurotropic activity of cobra and vipera versus mammalian NGFs, by using a novel bioassay involving PC12 cells genetically engineered to overexpress NGF-trkA receptors of human origin. These cells respond to NGF by differentiation (morphologically expressed as neurite outgrowth) by a process mediated by NGF-trkA receptors. This process was evaluated by two different criteria: (1) elongation of neurites (E), and (2) Percentage of responsive cells (PRC) determined by digital acquisition of data and computer analysis. We found that snake venom NGFs were less potent than mouse NGF, and that cobra NGF was more potent than vipera NGF. These data indicate the following order of NGF activity towards recombinant human trkA receptors: recombinant human NGF>mouse NGF>cobra NGF>vipera NGF. The neurotropic efficacy of these NGFs was found to be similar, reaching 80-90% of maximal activity obtained with all NGF forms. Interestingly, cobra (but not vipera) NGF demonstrated prolonged neurotropic activity compared with mouse NGF. The results of the present study indicate that cobra and vipera venom NGFs represent natural agonists of human trkA-receptor of a lower potency, but of similar efficacy, compared with mammalian NGFs. These compounds are important pharmacological tools to characterize the trkA receptor structure-function relationship, and to develop novel neurotropic drugs.

Animals↗
PubMed1997

Distinct bothrojaracin isoforms produced by individual jararaca (Bothrops jararaca) snakes.

Bothrojaracin (apparent mol. wt 27,000) is a potent inhibitor of thrombin previously isolated from the venom of Bothrops jararaca. Several molecular variants (isoforms) have been identified in a pool of venom collected from a large number of animals. In order to determine whether an individual snake produces a single type of bothrojaracin or multiple isoforms, we analyzed the bothrojaracin content of venoms collected individually from six adult B. jararaca snakes. Bothrojaracin was found in all venoms, but its activity was especially high in three of them. After purification on an alpha-thrombin affinity column, followed by gel filtration on Superose 12 HR, proteins from these three venoms migrated on sodium dodecyl sulfate-polyacrylamide gel electrophoresis as single bands of 27,000 and their amino-terminal sequences (residues 1-28) revealed extensive homology with bothrojaracin. In contrast, the material purified from the three venoms with low bothrojaracin activity consisted of bothrojaracin together with inactive proteins. Differences in the sequences obtained for bothrojaracin isolated from individual venoms indicated the existence of more than one isoform in the venom of an individual snake.

Amino Acid Sequence↗
PubMed1997

Toxins isolated from the venom of the Brazilian coral snake (Micrurus frontalis frontalis) include hemorrhagic type phospholipases A2 and postsynaptic neurotoxins.

Toxins isolated from the venom of the Brazilian coral snake (Micrurus frontalis frontalis) include hemorrhagic type phospholipases A2 and postsynaptic neurotoxins. Toxicon 35, 1193-1203, 1997.-Two sets of proteins have been purified from the venom of the Brazilian coral snake, Micrurus frontalis frontalis. One set has mol. wts, as shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), in the 8000-13,000 range and includes some proteins which are toxic to mice and others which are not. These proteins appear to be isoforms of postsynaptic toxins. The other set shows phospholipase A2 (PLA2) activity and the toxic members of this set promote hemorrhage in mice in a manner closely resembling that produced by PLA2s isolated from the venom of the Australian tiger snake (Notechis scutatus scutatus). These PLA2s migrate on SDS-PAGE with apparent mol. wts in the 18,000-22,000 range which is characteristic of PLA2s that have an alpha-helix D similar to pancreatic PLA2s. Elapid venom PLA2s of the type which typically migrate on SDS-PAGE with mol. wts in the 13,000-16,000 range and do not have alpha-helix D have not been detected in M. f. frontalis venom.

Animals↗