Neutralization of toxic and enzyme activities of 4 venoms from snakes of Guatemala and Honduras by the polyvalent antivenin produced in Costa Rica

We studied the ability of the polyvalent antivenom produced in Costa Rica to neutralize lethal, hemorrhagic, edema-forming, proteolytic, hemolytic, hyaluronidase and fibrinolytic activities of the venoms of Bothrops asper and B. nummifer from Honduras, and of Agkistrodon bilineatus and Crotalus durissus durissus from Guatemala. Neutralizing ability of antivenom was expressed as ED50 (effective dose 50%), defined as the antivenom/venom ratio at which the activity of the venom is reduced 50%. Antivenom is highly effective in the neutralization of lethal, hemorrhagic, hemolytic, hyaluronidase, and caseinolytic activities of B. asper, B. nummifer, and C. d. durissus venoms. In the case of B. nummifer venom, neutralization of fibrinolytic effect was only partial, whereas this activity was adequately neutralized when studying the venoms of B. asper and C. d. durissus. The venom of A. bilineatus was adequately neutralized by the antivenom, with the only exception of hemolytic effect that was reduced only partially. However, in quantitative terms, a relatively large volume of antivenom was required to neutralize some effects induced by A. bilineatus venom. Regarding edema-forming activity, antivenom neutralized efficiently the venoms of B. asper and A. bilineatus, whereas that of B. nummifer was neutralized only partially; on the other hand, edema induced by the venom of C. d. durissus was not neutralized at all. Immunochemical results indicate a close immunological relationship between venoms of B. asper, B. nummifer and C. d. durissus collected in Honduras and Guatemala with those of the same species collected in Costa Rica. Interspecies comparison, however, showed variation between venoms obtained from different species.(ABSTRACT TRUNCATED AT 250 WORDS)     

Snake venomics of the Lesser Antillean pit vipers Bothrops caribbaeus and Bothrops lanceolatus: correlation with toxicological activities and immunoreactivity of a heterologous antivenom

The venom proteomes of the snakes Bothrops caribbaeus and Bothrops lanceolatus, endemic to the Lesser Antillean islands of Saint Lucia and Martinique, respectively, were characterized by reverse-phase HPLC fractionation, followed by analysis of each chromatographic fraction by SDS-PAGE, N-terminal sequencing, MALDI-TOF mass fingerprinting, and collision-induced dissociation tandem mass spectrometry of tryptic peptides. The venoms contain proteins belonging to seven ( B. caribbaeus) and five ( B. lanceolatus) types of toxins. B. caribbaeus and B. lanceolatus venoms contain phospholipases A 2, serine proteinases, l-amino acid oxidases and zinc-dependent metalloproteinases, whereas a long disintegrin, DC-fragments and a CRISP molecule were present only in the venom of B. caribbaeus, and a C-type lectin-like molecule was characterized in the venom of B. lanceolatus. Compositional differences between venoms among closely related species from different geographic regions may be due to evolutionary environmental pressure acting on isolated populations. The venoms of these two species differed in the composition and the relative abundance of their component toxins, but they exhibited similar toxicological and enzymatic profiles in mice, characterized by lethal, hemorrhagic, edema-forming, phospholipase A 2 and proteolytic activities. The venoms of B. caribbaeus and B. lanceolatus are devoid of coagulant and defibrinogenating effects and induce only mild local myotoxicity in mice. The characteristic thrombotic effect described in human envenomings by these species was not reproduced in the mouse model. The toxicological profile observed is consistent with the abundance of metalloproteinases, PLA 2s and serine proteinases in the venoms. A polyvalent (Crotalinae) antivenom produced in Costa Rica was able to immunodeplete approximately 80% of the proteins from both B. caribbaeus and B. lanceolatus venoms, and was effective in neutralizing the lethal, hemorrhagic, phospholipase A 2 and proteolytic activities of these venoms.     

Geographic and ontogenic variability in the venom of the neotropical rattlesnake Crotalus durissus: pathophysiological and therapeutic implications

A comparative study was performed on the venoms of adult specimens of the neotropical rattlesnake, Crotalus durissus, from Guatemala, Costa Rica, Venezuela and Brazil, together with the venom of newborn specimens of C. d. durissus from Costa Rica. Venoms from Brazil (C. d. terrificus) and from newborn specimens of C. d. durissus presented an electrophoretic pattern characterized by the predominance of bands with molecular mass of 36 and 15 kDa, whereas those of adult specimens of C. d. durissus from Guatemala and Costa Rica, and C. d. cumanensis from Venezuela, showed a conspicuous band of 62 kDa, and additional bands of 36, 29 and 15 kDa. Moreover, venoms from C. d. terrificus and C. d. cumanensis showed a prominent band of < 10 kDa that probably corresponds to crotamine, since a 'crotamine-like' activity was detected in these venoms upon intraperitoneal injection in mice. Venoms of C. d. terrificus, C. d cumanensis and newborn C. d. durissus induced higher lethal and myotoxic effects than those of adult C. d. durissus. In contrast, adult C. d. durissus and C. d. cumanensis venoms induced hemorrhage, whereas venoms of C. d. terrificus and newborn C. d. durissus lacked this effect. All venoms showed coagulant effect in plasma, the highest activity being observed in the venom of newborn C. d. durissus. An anti-crotalic antivenom produced by Instituto Butantan (Brazil), using C. d. terrificus venom as antigen, was effective in the neutralization of lethal, myotoxic and coagulant effects of all venoms studied, being ineffective in the neutralization of hemorrhagic activity of the venoms of C. d. cumanensis and C. d. durissus. On the other hand, a polyvalent antivenom produced by Instituto Clodomiro Picado (Costa Rica), using the venoms of C. d. durissus. Bothrops asper and Lachesis stenophrys as antigens, was able to neutralize lethal, myotoxic, coagulant and hemorrhagic effects of C. d. durissus venom, but was ineffective in the neutralization of lethality and myotoxicity of C. d. terrificus, C. d. cumanensis and newborn C. d. durissus venom. The high toxicity of South American and newborn C. d. durissus venoms is related to the presence of high concentrations of the neurotoxic phospholipase A2 complex 'crotoxin'. Accordingly, antivenom from Instituto Butantan has a much higher titer of anti-crotoxin antibodies than antivenom from Instituto Clodomiro Picado. Crotalus durissus represents an example of intraspecies variation in venom composition and pharmacology that has relevant pathophysiologic and therapeutic implications.     

Snake population venomics and antivenomics of Bothrops atrox: Paedomorphism along its transamazonian dispersal and implications of geographic venom variability on snakebite management

We describe two geographically differentiated venom phenotypes across the wide distribution range of Bothrops atrox, from the Colombian Magdalena Medio Valley through Puerto Ayacucho and El Paují, in the Venezuelan States of Amazonas and Orinoquia, respectively, and S?o Bento in the Brazilian State of Maranh?o. Colombian and Venezuelan venoms show an ontogenetic toxin profile phenotype whereas Brazilian venoms exhibit paedomorphic phenotypes. Venoms from each of the 16 localities sampled contain both population-specific toxins and proteins shared by neighboring B. atrox populations. Mapping the molecular similarity between conspecific populations onto a physical map of B. atrox range provides clues for tracing dispersal routes that account for the current biogeographic distribution of the species. The proteomic pattern is consistent with a model of southeast and southwest dispersal and allopatric fragmentation northern of the Amazon Basin, and trans-Amazonian expansion through the Andean Corridor and across the Amazon river between Monte Alegre and Santarém. An antivenomic approach applied to assess the efficacy towards B. atrox venoms of two antivenoms raised in Costa Rica and Brazil using Bothrops venoms different than B. atrox in the immunization mixtures showed that both antivenoms immunodepleted very efficiently the major toxins (PIII-SVMPs, serine proteinases, CRISP, LAO) of paedomorphic venoms from Puerto Ayacucho (Venezuelan Amazonia) through S?o Bento, but had impaired reactivity towards PLA(2) and P-I SVMP molecules abundantly present in ontogenetic venoms. The degree of immunodepletion achieved suggests that each of these antivenoms may be effective against envenomations by paedomorphic, and some ontogenetic, B. atrox venoms.     

Venom of the crotaline snake Atropoides nummifer (jumping viper) from Guatemala and Honduras: comparative toxicological characterization,isolation of a myotoxic phospholipase A2 homologue and neutralization by two antivenoms

A comparative study was performed on the venoms of the crotaline snake Atropoides nummifer from Guatemala and Honduras. SDS-polyacrylamide gel electrophoresis, under reducing conditions, revealed a highly similar pattern of these venoms, and between them and the venom of the same species from Costa Rica. Similar patterns were also observed in ion-exchange chromatography on CM-Shephadex C-25, in which a highly basic myotoxic fraction was present. This fraction was devoid of phospholipase A₂ activity and strongly reacted, by enzyme-immunoassay, with an antiserum against Bothrops asper myotoxin II, a Lys-49 phospholipase A₂ homologue. A basic myotoxin of 16 kDa was isolated to homogeneity from the venom of A. nummifer from Honduras, showing amino acid composition and N-terminal sequence similar to those of Lys-49 phospholipase A₂ variants previously isolated from other crotaline snake venoms. Guatemalan and Honduran A. nummifer venoms have a qualitatively similar toxicological profile, characterized by: lethal; hemorrhagic; myotoxic; edema-forming; coagulant; and defibrinating activities, although there were significant quantitative variations in some of these activities between the two venoms. Neutralization of toxic activities by two commercially-available antivenoms in the region was studied. Polyvalent antivenom produced by Instituto Clodomiro Picado was effective in the neutralization of: lethal; hemorrhagic; myotoxic; coagulant; defibrinating; and phospholipase A₂ activities, but ineffective against edema-forming activity. On the other hand, MYN polyvalent antivenom neutralized: hemorrhagic; myotoxic; coagulant; defibrinating; and phospholipase A₂ activities, albeit with a lower potency than Instituto Clodomiro Picado antivenom. MYN antivenom failed to neutralize lethal and edema-forming activities of A. nummifer venoms.     

Hemolytic activities of stinging insect venoms

The direct hemolytic activities of the venoms from 21 species of stinging insects were determined. The activities spanned 3 1/2 orders of magnitude, ranging from a low of four to a high of 12,000 hemolytic units/mg dry venom, respectively, for the solitary wasp, Dasymutilla lepeletierii, and the social wasp, Polistes infuscatus. The latter activity is the highest reported for any insect venom and represents a level that is potentially harmful to humans stung by the wasp. The social wasps as a group generally possessed highly hemolytic venoms; the ants, poorly hemolytic venoms; and the solitary stinging species, venoms with extremely low activity. For the venoms, hemolytic activity correlated with neither lethal toxicity (LD₅₀) nor algogenicity. This finding suggests that hemolysins alone do not determine venom toxicity, and that the hemolysins of stinging insect venoms serve a variety of poorly understood roles. The range of activity of hemolysins from different venoms indicates they probably have different chemical structures and functions.     

Snake venomics and antivenomics of Bothrops atrox venoms from Colombia and the Amazon regions of Brazil, Perú and Ecuador suggest the occurrence of geographic variation of venom phenotype by a trend towards paedomorphism

The venom proteomes of Bothrops atrox from Colombia, Brazil, Ecuador, and Perú were characterized using venomic and antivenomic strategies. Our results evidence the existence of two geographically differentiated venom phenotypes. The venom from Colombia comprises at least 26 different proteins belonging to 9 different groups of toxins. PI-metalloproteinases and K49-PLA₂ molecules represent the most abundant toxins. On the other hand, the venoms from Brazilian, Ecuadorian, and Peruvian B. atrox contain predominantly PIII-metalloproteinases. These toxin profiles correlate with the venom phenotypes of adult and juvenile B. asper from Costa Rica, respectively, suggesting that paedomorphism represented a selective trend during the trans-Amazonian southward expansion of B. atrox through the Andean Corridor. The high degree of crossreactivity of a Costa Rican polyvalent (Bothrops asper, Lachesis stenophrys, Crotalus simus) antivenom against B. atrox venoms further evidenced the close evolutionary kinship between B. asper and B. atrox. This antivenom was more efficient immunodepleting proteins from the venoms of B. atrox from Brazil, Ecuador, and Perú than from Colombia. Such behaviour may be rationalized taking into account the lower content of poorly immunogenic toxins, such as PLA₂ molecules and PI-SVMPs in the paedomorphic venoms. The immunological profile of the Costa Rican antivenom strongly suggests the possibility of using this antivenom for the management of snakebites by B. atrox in Colombia and the Amazon regions of Ecuador, Perú and Brazil.     

Snake venomics and antivenomics of the arboreal neotropical pitvipers Bothriechis lateralis and Bothriechis schlegelii

We report the comparative proteomic characterization of the venoms of two related neotropical arboreal pitvipers from Costa Rica of the genus Bothriechis, B. lateralis (side-striped palm pit viper) and B. schlegelii (eyelash pit viper). The crude venoms were fractionated by reverse-phase HPLC, followed by analysis of each chromatographic fraction by SDS-PAGE, N-terminal sequencing, MALDI-TOF mass fingerprinting, and collision-induced dissociation tandem mass spectrometry of tryptic peptides. The venom proteomes of B. lateralis and B. schlegelii comprise similar number of distinct proteins belonging, respectively, to 8 and 7 protein families. The two Bothriechis venoms contain bradykinin-potentiating peptides (BPPs), and proteins from the phospholipase A 2 (PLA 2), serine proteinase, l-amino acid oxidase (LAO), cysteine-rich secretory protein (CRISP), and Zn (2+)-dependent metalloproteinase (SVMP) families, albeit each species exhibit different relative abundances. Each venom also contains unique components, for example, snake venom vascular endothelial growth factor (svVEGF) and C-type lectin-like molecules in B. lateralis, and Kazal-type serine proteinase inhibitor-like proteins in B. schlegelii. Using a similarity coefficient, we estimate that the similarity of the venom proteins between the two Bothriechis taxa may be <10%, indicating a high divergence in their venom compositions, in spite of the fact that both species have evolved to adapt to arboreal habits. The major toxin families of B. lateralis and B. schlegelii are SVMP (55% of the total venom proteins) and PLA 2 (44%), respectively. Their different venom toxin compositions provide clues for rationalizing the distinct signs of envenomation caused by B. schlegelii and B. lateralis. An antivenomic study of the immunoreactivity of the Instituto Clodomiro Picado (ICP) polyvalent antivenom toward Bothriechis venoms revealed that l-amino acid oxidase and SVMPs represent the major antigenic protein species in both venoms. Our results provide a ground for rationalizing the reported protection of the ICP polyvalent antivenom against the hemorrhagic, coagulant, defibrinating, caseinolytic and fibrin(ogen)olytic activities of Bothriechis ( schlegelii, lateralis) venoms. However, these analyses also evidenced the limited recognition capability of the polyvalent antivenom toward a number of Bothriechis venom components, predominantly BPPs, svVEGF, Kazal-type inhibitors, some PLA 2 proteins, some serine proteinases, and CRISP molecules.     

Comparative enzymatic composition of Brazilian coral snake (Micrurus) venoms.

1. Venoms of 11 coral snake taxa, including Micrurus albicinctus, M. corallinus, M. frontalis altirostris, M. f. brasiliensis, M. f. frontalis, M. fulvius fulvius, M. ibiboboca, M. lemniscatus ssp., M. randonianus, M. spixii spixii, and M. surinamensis surinamensis, were examined for 13 enzymatic activities. 2. These were compared with venoms of three outgroup taxa: Naja naja kaouthia, Bungarus multicinctus, and Bothrops moojeni. 3. Enzyme activity levels in Micrurus venoms were highly variable from species to species. 4. All venoms possessed phospholipase activity. 5. Protease activity against synthetic or dyed natural substrates was generally negligible in all elapid venoms examined. By contrast, most Micrurus venoms displayed ample L-leucine aminopeptidase activity. 6. Venom of M.s. surinamensis was significantly different from those of its congeners in most assays.     

Snake venomics and antivenomics of Bothrops atrox venoms from Colombia and the Amazon regions of Brazil,Perú and Ecuador suggest the occurrence of geographic variation of venom phenotype by a trend towards paedomorphism

The venom proteomes of Bothrops atrox from Colombia, Brazil, Ecuador, and Perú were characterized using venomic and antivenomic strategies. Our results evidence the existence of two geographically differentiated venom phenotypes. The venom from Colombia comprises at least 26 different proteins belonging to 9 different groups of toxins. PI-metalloproteinases and K49-PLA₂ molecules represent the most abundant toxins. On the other hand, the venoms from Brazilian, Ecuadorian, and Peruvian B. atrox contain predominantly PIII-metalloproteinases. These toxin profiles correlate with the venom phenotypes of adult and juvenile B. asper from Costa Rica, respectively, suggesting that paedomorphism represented a selective trend during the trans-Amazonian southward expansion of B. atrox through the Andean Corridor. The high degree of crossreactivity of a Costa Rican polyvalent (Bothrops asper, Lachesis stenophrys, Crotalus simus) antivenom against B. atrox venoms further evidenced the close evolutionary kinship between B. asper and B. atrox. This antivenom was more efficient immunodepleting proteins from the venoms of B. atrox from Brazil, Ecuador, and Perú than from Colombia. Such behaviour may be rationalized taking into account the lower content of poorly immunogenic toxins, such as PLA₂ molecules and PI-SVMPs in the paedomorphic venoms. The immunological profile of the Costa Rican antivenom strongly suggests the possibility of using this antivenom for the management of snakebites by B. atrox in Colombia and the Amazon regions of Ecuador, Perú and Brazil.     

Comparative study of the edema-forming activity of Costa Rican snake venoms and its neutralization by a polyvalent antivenom

The edema-forming activity of eight Costa Rican crotaline snake venoms and its neutralization by a polyvalent antivenom were studied using the mouse footpad test. All of the venoms induced edema, the highest activity being present in the venoms of Bothrops lateralis and Bothrops picadoi. When experiments were performed with preincubation of venom and antivenom, neutralization of edema was poor. Moreover, it was observed that, with some venoms, edema increased when large doses of antivenom were used. This effect was also observed when some venoms were incubated with coral snake antivenom, suggesting that venoms may release some pharmacologically active component(s) from antivenom, since the latter contains traces of alpha-2 and beta globulins. Based on these findings, an alternative approach to the study of the neutralization of edema was used; in this new method, antivenom was injected i.v. before venom administration, thereby avoiding preincubation. With this technique, a much better neutralization of edema was observed, although with some venoms it was still poor. Venoms contain low molecular weight factors which induce edema, suggesting that lack of immunogenicity of some components may cause a poor neutralization. However, such components are responsible for only a minor portion of the edema induced by crude venoms. It is suggested that experiments in which venom and antivenom are preincubated preincubated in testing the neutralization of edema should be avoided, and that a more adequate approach may be an independent inoculation of venom and antivenom.     

Hemolytic potency and phospholipase activity of some bee and wasp venoms

1. The action of crude venoms of four aculeate species: Apis mellifera, Vespa crabro, Vespula germanica and Vespula vulgaris on human erythrocytes was investigated in order to determine the lytic and phospholipase activity of different aculeate venoms and their ability to induce red blood cell hemolysis. 2. Bee venom was the only extract to completely lyse red blood cells at the concentration of 2-3 micrograms/ml. 3. Phospholipase activity in all of the examined vespid venoms was similar and the highest value was recorded in V. germanica. 4. Vespid venoms exhibited phospholipase B activity, which is lacking in honeybee venom. 5. In all membrane phospholipids but lecithin, lysophospholipase activity of vespid venoms was 2-6 times lower than the relevant phospholipase activity. 6. The incubation of red blood cells with purified bee venom phospholipase A2 was not accompanied by lysis and, when supplemented with purified melittin, the increase of red blood cell lysis was approximately 30%.     

Age-related Variation in Snake Venom： Evidence from Two Snakes （Naja atra and Deinagkistrodon acutus） in Southeastern China

In this study we explored electrophoretic profiles, enzymatic activities and immunoreactivity of neonate and adult venoms from two snakes （Naja atra and Deinagkistrodon acutus） coexisting in southeastern China. Age-related variation in electrophoretic profiles was found in both species and proteolytic and fibrinogenolytic activity was higher in neonate than adult venoms. Neonate D. acutus venom had higher 5＇ nucleotidase, PLA2, hyaluronidase and gelatinolytie activity, but lower esterolytic activity, than adult venom. Neonate and adult D. acutus venoms showed identical phosphomonoesterase, LAO and fibrinolytic activities. Neonate N. atra venom had higher phosphomonoesterase and LAO activity, but lower 5＇ nucleotidase, PLA2, hyaluronidase and Ache activities than adult venom. Neonate and adult N. atra venoms showed similar gelatinolytic activity. Further, age-dependent immunoreactivity was found in both species, and cross-reactions between homologous venoms and antiserums were closely related to venom composition. We speculate that age-related variation in venom characteristics is possibly driven by evolutionary forces associated with ontogenetic shifts in dietary habits, competition and predation pressure.     

A comparative study of the biological properties of Dendroaspis (mamba) snake venoms.

1. The biological properties of twelve samples of venoms from all four species of Dendroaspis (mamba) were investigated. 2. Dendroaspis venoms generally exhibited very low levels of protease, phosphodiesterase and alkaline phosphomonoesterase; low to moderately low level of 5'-nucleotidase and very high hyaluronidase activities, but were devoid of L-amino acid oxidase, phospholipase A, acetylcholinesterase and arginine ester hydrolase activities. The unusual feature in venom enzyme content can be used to distinguish Dendroaspis venoms from other snake venoms. 3. All Dendroaspis venoms did not exhibit hemorrhagic or procoagulant activity. Some Dendroaspis venoms, however, exhibited strong anticoagulant activity. The intravenous median lethal dose of the venoms ranged from 0.5 microgram/g mouse to 4.2 micrograms/g mouse. 4. Venom biological activities are not very useful for the differentiation of the Dendroaspis species. The four Dendroaspis venoms, however, can be differentiated by their venom SDS-polyacrylamide gel electrophoretic patterns.     

Ontogenetic Variation in Biological Activities of Venoms from Hybrids between Bothrops erythromelas and Bothrops neuwiedi Snakes

Lance-headed snakes are found in Central and South America, and they account for most snakebites in Brazil. The phylogeny of South American pitvipers has been reviewed, and the presence of natural and non-natural hybrids between different species of Bothrops snakes demonstrates that reproductive isolation of several species is still incomplete. The present study aimed to analyze the biological features, particularly the thrombin-like activity, of venoms from hybrids born in captivity, from the mating of a female Bothrops erythromelas and a male Bothrops neuwiedi, two species whose venoms are known to display ontogenetic variation. Proteolytic activity on azocoll and amidolytic activity on N-benzoyl-DL-arginine-p-nitroanilide hydrochloride (BAPNA) were lowest when hybrids were 3 months old, and increased over body growth, reaching values similar to those of the father when hybrids were 12 months old. The clotting activity on plasma diminished as hybrids grew; venoms from 3- and 6-months old hybrids showed low clotting activity on fibrinogen (i.e., thrombin-like activity), like the mother venom, and such activity was detected only when hybrids were older than 1 year of age. Altogether, these results point out that venom features in hybrid snakes are genetically controlled during the ontogenetic development. Despite the presence of the thrombin-like enzyme gene(s) in hybrid snakes, they are silenced during the first six months of life.     

Alarm in a wasp-wasp nesting association: Do members signal cross-specifically?

Summary We studied interspecific alarm communication between two species of social wasps in a nesting association in northwestern Costa Rica by testing the alarm responses ofPolybia occidentalis andMischocyttarus immarginatus to venom of both species. This is the first investigation of alarm pheromone in the genusMischocyttarus. M. immarginatus did not respond with alarm behavior to the venom of either species.P. occidentalis, which responds to its own venom with alarm behavior (Jeanne, 1981), also responded with alarm behavior to the venom ofM. immarginatus, but with much less intensity. Since heterospecific venoms did not release species-typical levels of alarm behavior, we conclude that interspecific alarm signalling plays no role in the nesting association.     

Kinins in ant venoms--a comparison with venoms of related Hymenoptera

1. Venom preparations have been made of six ant, one pompilid wasp, two mutillid wasp, and four social wasp species. 2. The venoms were analysed pharmacologically in order to detect kinin-like activity. 3. Due to the small amounts of venoms available only a cascade of smooth muscle preparation could be used. 4. Kinin activities have been found in five ant venoms and in four social wasp venoms. 5. No kinin activity has been found in the venoms of the pompilid and mutillid wasps. 6. All ant venoms also contain unidentified agonists for vertebrate smooth muscle preparations.     

Studies of the necrotic actions of the venoms of several Australian spiders.

1. Raw venoms from a number of Australian Araneomorph spiders were found to cause epidermal disruption in cultured skin from both mice and humans. 2. The more potent ones also caused loss of epidermal cell-cell adhesion of mouse skin in vivo. 3. Raw venoms from three Mygalomorph species did not have these actions. 4. Venom gland extracts from the Araneomorph species were also ineffective. 5. It was concluded that where spider venoms appear to possess necrogenic activity the most likely reason for this is contamination of the venoms with digestive tract secretions.     

North-south regional variation in phospholipase A activity in the venom of Crotalus ruber.

1. Twenty-seven individual venoms from the rattlesnake species Crotalus ruber from different regions were comparatively analyzed by reverse-phase HPLC and analyzed for phospholipase A (PLA) content using a polarographic assay. 2. Two fractions containing PLA activity were detected by HPLC in the venoms of all the C. ruber specimens from southern Baja, Mexico, but specimens from southern California, U.S.A., were lacking corresponding fractions and were extremely low or lacking in PLA activity in their venoms. 3. The north-south regional variation in PLA content in C. ruber venom does not correlate with the north-south ranges (based on external morphology) of the subspecies C. ruber ruber and C. ruber lucasensis.