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At least 37 records · Page 2Linked to original sources

PubMed2004

How snakes eat snakes: the biomechanical challenges of ophiophagy for the California kingsnake, Lampropeltis getula californiae (Serpentes: Colubridae).

In this study we investigated how ophiophagous snakes are able to ingest prey snakes that equal or exceed their own length. We used X-ray video, standard video, dissection, and still X-rays to document the process of ophiophagy in kingsnakes (Lampropeltis getula) feeding on corn snakes (Elaphe guttata). Most kingsnakes readily accepted the prey snakes, subdued them by constriction, and swallowed them head first. In agreement with previous observations of ophiophagy, we found that the predator snake forces the vertebral column of the prey snake to bend into waves. These waves shorten the prey's body axis and allow it to fit inside the gastrointestinal (GI) tract and body cavity of the predator. Dissection of a kingsnake immediately following ingestion revealed extensive longitudinal stretching of the anterior portion of the GI tract (oesophagus and stomach), and no visible incursion of the prey into the intestine. X-ray video of ingestion showed that the primary mechanism of prey transport was the pterygoid walk, with some contribution from concertina-like compression and extension cycles of the predator's vertebral column in two out of three observations. Complete digestion was observed in only one individual, as others regurgitated before digestion was finished. X-ray stills taken every 4 days following ingestion revealed that the corn snakes were about half digested within the first 4 days, and digestion was complete within 15 days.

Journal Article↗

PubMed1983

The inactivating effect of Bothrops jararaca and Waglerophis merremii snake plasma on the coagulant activity of various snake venoms.

Plasmas of the poisonous snake Bothrops jararaca and of the non-poisonous snake Waglerophis merremii were not clotted by various snake venoms. These plasmas also inactivated venom clotting activity on human plasma. This effect was absent in snake serum and in heated snake plasma. The active fraction was isolated by gel chromatography from B. jararaca plasma and corresponded to the fibrinogen-containing fractions. It is suggested that the inactivation by snake plasma of the venom coagulant activity might be due to a fibrinogen-bound complex or to fibrinogen itself.

Animals↗

PubMed2003

Comparison of the in vitro neuromuscular activity of venom from three Australian snakes (Hoplocephalus stephensi, Austrelaps superbus and Notechis scutatus): efficacy of tiger snake antivenom.

1. Tiger snake antivenom, raised against Notechis scutatus venom, is indicated not only for the treatment of envenomation by this snake, but also that of the copperhead (Austrelaps superbus) and Stephen's banded snake (Hoplocephalus stephensi). The present study compared the neuromuscular pharmacology of venom from these snakes and the in vitro efficacy of tiger snake antivenom. 2. In chick biventer cervicis muscle and mouse phrenic nerve diaphragm preparations, all venoms (3-10 microg/mL) produced inhibition of indirect twitches. In the biventer muscle, venoms (10 micro g/mL) inhibited responses to acetylcholine (1 mmol/L) and carbachol (20 micromol/L), but not KCl (40 mmol/L). The prior (10 min) administration of 1 unit/mL antivenom markedly attenuated the neurotoxic effects of A. superbus and N. scutatus venoms (10 microg/mL), but was less effective against H. stephensi venom (10 microg/mL); 5 units/mL antivenom attenuated the neurotoxic activity of all venoms. 3. Administration of 5 units/mL antivenom at t90 partially reversed, over a period of 3 h, the inhibition of twitches produced by N. scutatus (10 microg/mL; 41% recovery), A. superbus (10 microg/mL; 25% recovery) and H. stephensi (10 microg/mL; 50% recovery) venoms. All venoms (10-100 microg/mL) also displayed signs of in vitro myotoxicity. 4. The results of the present study indicate that all three venoms contain neurotoxic activity that is effectively attenuated by tiger snake antivenom.

Agkistrodon↗

PubMed2005

[Biogeographical distribution of snakes in Cameroon: the case of venomous snakes].

A preliminary analysis of the distribution of snakes captured in Cameroon between 1999 and 2004 is presented in this study. This work helps to provide a better understanding of the distribution of the venomous snakes. The main focus of this study was to identify regions of high diversity of venomous species, a useful step towards developing a national strategy of snakebite care and antivenom distribution. We recorded 4,910 specimens of 150 species from 361 localities throughout Cameroon. Among the ten provinces in Cameroon, the southwest province recorded the highest number of venomous snakes. Diversity was less in the far-north province, but the high abundance of Echis ocellatus seems to be responsible for many snake bites in the region. Of all venomous snakes, the forest cobra Naja melanoleuca was the most abundant in the forest region. The humid savannah region was dominated by Causus maculatus while the Sahelian part by Echis ocellatus. Given the abundance and high snake bite cases of the latter in the region, snakebite care from a national point of view should begin from the far-north towards the forest region of the south-west Cameroon.

Animals↗

PubMed2000

T-snakes: topology adaptive snakes.

We present a new class of deformable contours (snakes) and apply them to the segmentation of medical images. Our snakes are defined in terms of an affine cell image decomposition (ACID). The 'snakes in ACID' framework significantly extends conventional snakes, enabling topological flexibility among other features. The resulting topology adaptive snakes, or 'T-snakes', can be used to segment some of the most complex-shaped biological structures from medical images in an efficient and highly automated manner.

Brain↗

PubMed2001

Cryptosporidium sp.-associated enteritis without gastritis in rough green snakes (Opheodrys aestivus) and a common garter snake (Thamnophis sirtalis).

An epizootic of severe Cryptosporidium sp.-associated enteritis occurred in a group of 15 wild-caught juvenile rough green snakes (Opheodrys aestivus) at the Baltimore Zoo quarantine facility. All of the animals died with no premonitory signs. Histopathologic examination of the small and proximal large intestine of eight of the green snakes showed moderate to severe Cryptosporidium sp. infection and enteritis characterized by dense heterophilic and lymphocytic inflammatory infiltrates throughout the lamina propria with epithelial necrosis. Cryptosporidium sp. was also found in feces of an adult common garter snake (Thamnophis sirtalis) that was wild caught on zoo grounds and held in quarantine during the epizootic. After euthanasia, histologic examination of the garter snake showed a severe small intestinal Cryptosporidium sp. infection with only mild enteritis consisting of sparse heterophilic and lymphocytic infiltrates. There was no gross or histologic evidence of Cryptosporidium sp. gastritis in the nine snakes evaluated, and this is the first report of Cryptosporidium sp.-associated enteritis in snakes without gastric lesions.

Animals↗

PubMedDate not supplied

Snake venoms in science and clinical medicine. 2. Applied immunology in snake venom research.

Enzyme-linked immunosorbent assay (ELISA) is a very important tool for studying both the epidemiology and clinical effects of snake bite in man. For epidemiology ELISA depends on the development and persistence of specific humoral venom antibody in previous snake bite victims. In the Nigerian savanna 63% of previous bite victims possessed specific venom antibodies against Echis carinatus venom; in Ecuador, where there is a 5% annual mortality due to snake bite in a population of Waorani Indians, venom antibodies against a wide range of different venoms were identified in previous bite victims using ELISA. In certain areas it is often not possible, using the symptoms of envenoming, to determine which species of snake has bitten the patient. Field studies using ELISA in Nigeria and Thailand have been successful in establishing the species responsible for envenoming. Current studies are in progress on the development of a rapid immunoassay which should be capable of detecting the biting species within 5-10 min of sampling from the admission patient. This will be useful for the clinician as it will enable the rapid detection of the species responsible for envenoming and, therefore, the use of the correct antivenom. Experimental work on the development of new methods of antivenom production includes immunization of experimental animals with venom/liposome preparations, the preparation of venom antigens using monoclonal antibodies on affinity columns, and recombinant deoxyribonucleic acid technology. Liposomal immunization requires only a single injection of venom to obtain a rapid, high level and protective immune response. Venom liposomes may also be given orally resulting in a serum immunoglobulin G immune response in experimental animals. Use of such a system may eventually result in immunization of man in areas of high snake bite incidence and mortality.

Animals↗

PubMed2005

Low dose of snake antivenom is as effective as high dose in patients with severe neurotoxic snake envenoming.

The objective of this study was to evaluate the effects of two different dosage protocols on the outcome of patients with severe neurotoxic snake envenoming, using a retrospective analysis of patients admitted with a diagnosis of severe neurotoxic snake bite over a 4 year period. In the study, 55 snake bite victims requiring ventilatory support for severe neurotoxic envenoming received either 150 ml of polyvalent snake antivenom (SAV) (low dose SAV group, n = 28) or 100 ml of SAV at presentation followed by 100 ml every 6 hours until recovery of neurological manifestations (high dose group, n = 27). The median dose of SAV in the high dose group was 600 ml (range 300 to 1600). The duration of mechanical ventilation in the low dose group (median 47.5 hours; range 14 to 248) was similar to that in the high dose group (median 44 hours; range 6 to 400). The mean (SD) duration of intensive care unit stay was similar in the two groups. There were three deaths in the high dose group; two patients in the low dose group had neurological sequelae. All other patients improved, had no residual neurological deficit, and were discharged. We conclude that there is no difference between a protocol using lower doses of SAV and one with higher doses in the management of patients with severe neurotoxic snake envenoming.

Adult↗

PubMed2006

The good, the bad and the ugly: Australian snake taxonomists and a history of the taxonomy of Australia's venomous snakes.

The Australian snake fauna is unique in harbouring more venomous species than non-venomous ones. Although taxonomic research on the elapid snakes of Australia goes back to the late 18th century, in stark contrast to other developed regions of the world (e.g. the continental USA), Australian snake taxonomy is very much in its infancy. Despite this, or perhaps because of this, the taxonomy of Australian snakes has been extraordinarily controversial, and many of the taxonomists involved correspondingly colourful. In this review, we explore the sometimes-tortured history of the taxonomic exploration of the venomous snake fauna of Australia, looking at some of the more colourful and notable contributors and highlighting systematic pitfalls that persist even today.

Animals↗

PubMed2003

Bile acid composition in snake bile juice and toxicity of snake bile acids to rats.

We determined the bile acid profiles in bile juice of snake gallbladders by HPLC on a silica gel RP-18 reversed-phase column. Cholic acid and chenodeoxycholic acid were predominant components in three of four snake species. To elucidate the toxic effect of snake bile acids on rats, a synthetic bile acid mixture was prepared mimicking the bile acid composition of a snake Naja naja atra bile juice. Twenty-four male Wistar rats were divided into four groups and treated orally at 3-day intervals with saline (control group) and different doses (1-3x doses) of the bile acid mixture. After treatment, the following parameters increased: the relative ratios of liver and kidney mass to body mass, the concentrations of red blood cell, hemoglobin and hematocrit in the blood, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, plasma urea nitrogen and creatinine in the plasma, and the levels of urine urea nitrogen and creatinine in the urine. Body mass of rats and the levels of Na+, K+, Ca++ in the urine of rats were significantly decreased, especially for groups treated with 2x and 3x doses of the bile acid mixture. Examination of liver and kidney pathology also showed cell enlargement and lesion in cell integrity in treated groups, especially for groups treated with 2x and 3x bile acid mixture, indicating that short-term toxicity of snake N. naja atra bile acids was significant in rats.

Administration, Oral↗

PubMed1991

Snake aggregation pheromones: source and chemosensory mediation in western ribbon snakes (Thamnophis proximus).

Aggregation with conspecifics is a robust phenomenon among snakes that is mediated by chemical cues, although the source of such cues is unknown. Adult western ribbon snakes (Thamnophis proximus) discriminated between skin lipid extracts from conspecifics and those from a sympatric heterospecific snake, the corn snake (Elaphe guttata). Additionally, ribbon snakes were attracted to conspecific skin lipid-marked shelters when paired with control-marked shelters, but no preference was exhibited when shelters marked with E. guttata skin lipids were paired with control-marked shelters. Furthermore, prevention of chemical access to the vomeronasal organs of T. proximus eliminated the ability to respond to conspecific skin lipids. These results indicate that epidermal lipids are the source of chemical cues mediating attraction to shelters marked by conspecifics and that such signals are detected by the vomeronasal system.

Animals↗

PubMed2006

Evidence for different origin of sex chromosomes in snakes, birds, and mammals and step-wise differentiation of snake sex chromosomes.

All snake species exhibit genetic sex determination with the ZZ/ZW type of sex chromosomes. To investigate the origin and evolution of snake sex chromosomes, we constructed, by FISH, a cytogenetic map of the Japanese four-striped rat snake (Elaphe quadrivirgata) with 109 cDNA clones. Eleven of the 109 clones were localized to the Z chromosome. All human and chicken homologues of the snake Z-linked genes were located on autosomes, suggesting that the sex chromosomes of snakes, mammals, and birds were all derived from different autosomal pairs of the common ancestor. We mapped the 11 Z-linked genes of E. quadrivirgata to chromosomes of two other species, the Burmese python (Python molurus bivittatus) and the habu (Trimeresurus flavoviridis), to investigate the process of W chromosome differentiation. All and 3 of the 11 clones were localized to both the Z and W chromosomes in P. molurus and E. quadrivirgata, respectively, whereas no cDNA clones were mapped to the W chromosome in T. flavoviridis. Comparative mapping revealed that the sex chromosomes are only slightly differentiated in P. molurus, whereas they are fully differentiated in T. flavoviridis, and E. quadrivirgata is at a transitional stage of sex-chromosome differentiation. The differentiation of sex chromosomes was probably initiated from the distal region on the short arm of the protosex chromosome of the common ancestor, and then deletion and heterochromatization progressed on the sex-specific chromosome from the phylogenetically primitive boids to the more advanced viperids.

Animals↗

PubMed1981

Aerobic bacterial oral flora of garter snakes: development of normal flora and pathogenic potential for snakes and humans.

Garter snakes that are used for scientific laboratory studies or kept as exotic pets often become ill and die early in captivity. They may also act as reservoirs of potential human pathogens or transmit infection to man. A total of 126 strains of aerobic and facultative bacteria, most potential human and snake pathogens, were isolated from 82 garter snake oropharyngeal cultures. Coagulase-negative Staphylococcus species were the most common species isolated. Acinetobacter calcoaceticus var. anitratus, Hafnia alvei, Arizona hinshawii, Salmonella species, Shigella species, Klebsiella oxytoca, and Pseudomonas aeruginosa were among the potential pathogens isolated. The spectrum of bacteria with potential for causing oral and pulmonary infections in garter snakes is greater than has been previously appreciated. Garter snakes should also be considered reservoirs of human pathogens, and appropriate precautions should be taken by laboratory personnel and pet owners.

Aerobiosis↗

PubMed2002

The primary structure of three hemoglobin chains from the indigo snake (Drymarchon corais erebennus, Serpentes): first evidence for alphaD chains and two beta chain types in snakes.

The hemoglobin of the indigo snake (Drymarchon corais erebennus, Colubrinae) consists of two components, HbA and HbD, in the ratio of 1:1. They differ in both their alpha and beta chains. The amino acid sequences of both a chains (alphaA and alphaD) and one beta chain (betaI) were determined. The presence of an alphaD chain in a snake hemoglobin is described for the first time. A comparison of all snake beta chain sequences revealed the existence of two paralogous beta chain types in snakes as well, which are designated as betaI and betaII type. For the discussion of the physiological properties of Drymarchon hemoglobin, the sequences were compared with those of the human alpha and beta chains and those of the closely related water snake Liophis milians where functional data are available. Among the heme contacts, the substitution alphaD58(E7)His-->Gln is unusual but most likely without any effect. The residues responsible for the main part of the Bohr effect are the same as in mammalian hemoglobins. In each of the three globin chains only two residues at positions involved in the alpha1/beta2 interface contacts, most important for the stability and the properties of the hemoglobin molecule, are substituted with regard to human hemoglobin. On the contrary, nine, eleven, and six alpha1/beta1 contact residues are replaced in the alphaA, alphaD, betaI chains, respectively.

Amino Acid Sequence↗

PubMed1998

Chemosignal transduction in the vomeronasal organ of garter snakes: cloning of a gene encoding adenylate cyclase from the vomeronasal organ of garter snakes.

We previously reported that ES20-receptor binding activates phosphoinositide (PI) turnover, resulting in an increase in inositol-1,4,5-trisphosphate, which in turn mobilizes intracellularly stored calcium in the vomeronasal (VN) sensory epithelium of garter snakes. We also found that the activity of adenylate cyclase (AC) in the VN organ is very sensitive to Ca2+ but insensitive to calmodulin regulation. A 250-bp fragment of adenylate cyclase type VI (AC-VI) was obtained from brain cDNA of garter snake by RT-PCR with degenerate primers. The 250-bp fragments were amplified, cloned, and sequenced. Both Northern blot and RNase protection assays revealed that the vomeronasal organ (VNO) and brain contained more abundance of AC type VI than the main olfactory epithelium. A 3.8-kb cDNA was then cloned from the vomeronasal cDNA library of garter snakes and sequenced. The 5' cDNA was obtained by means of 5' RACE PCR and sequenced. We have successfully cloned a 5200-nucleotide cDNA from VNO of garter snakes containing an open reading frame++ encoding 1150 amino acids of AC-VI protein. The vomeronasal AC is termed AC(VN) . AC(VN) shows a high degree of homology with type VI AC of rat, mouse, or human. In situ hybridization with digoxigenin-labeled cRNA demonstrated that AC(VN) mRNA was abundant in the sensory epithelium but not in the nonsensory epithelium of the mushroom body of the vomeronasal organ of garter snakes.

Adenylyl Cyclases↗

PubMed2002

Risk assessment of an acetaminophen baiting program for chemical control of brown tree snakes on Guam: evaluation of baits, snake residues, and potential primary and secondary hazards.

The brown tree snake (Boiga irregularis) is a significant ecological, agricultural, and economic pest on Guam. Acetaminophen has recently been identified as a promising snake toxicant. Subsequent experimentation has shown that acetaminophen-mouse baits are readily consumed by and acutely toxic to browntree snakes. Before implementing an island-wide acetaminophen-mouse baiting program for the reducton of brown tree snake populations,the potential risks to nontarget wildlife must be evaluated. Quantification of nontarget hazards by comparing potential exposure levels to toxicity values suggested a significant level of concern for rodents, cats, pigs, and birds. For these species, subsequent calculations and field and laboratory experiments, which quantified acetaminophen consumption under field conditions, indicated that acetaminophen consumption was minimal. These results indicate that the advantages of using acetaminophen to reduce brown tree snake populations on Guam outweigh the minimal risks to nontarget feral and wildlife species.

Acetaminophen↗

PubMed1975

Human snake bite victims: the successful detection of circulating snake venom by radiommunoassay,.

A new solid-phase radioimmunoassay has been developed which allows positive identification of the type of snake venom in human tissue and fluids and its accurate quantitation. Tiger snake venom at a level of 210 ng/ml was detected post mortem in the serum of a child, and brown snake venom was detected in two adults bitten by unidentified snakes. Apart from forensic applications, the assay will be useful in studying clinical aspects of envenomation and the use of antivenenes.

Adult↗

PubMed1991

Comparative study of nine Bothrops snake venoms from adult female snakes and their offspring.

Venoms of seven different Bothrops species and three subspecies (B. alternatus, B. cotiara, B. erythromelas, B. jararaca, B. jararacussu, B. moojeni, B. neuwiedi paranaensis. B.n. pauloensis and B.n. urutu) obtained from individual mothers and their young were investigated. Biometrics of snakes and protein content, toxicity (LD50), SDS-PAGE, proteolytic and clotting activities of venoms were estimated. Comparison of venoms from female snakes and their respective newborn offspring were variable in protein content, toxicity, fibrinolytic/amidolytic/thrombin-like activities and in venom yield in relation to snake length. B.n. paranaensis and B.n. pauloensis possessed the most toxic venoms. Caseinolytic activity of all venoms from female snakes and procoagulant activity of their offspring were consistently high. Venoms of B. erythromelas mother and offspring had no amidolytic activity and the highest levels of factor X and prothrombin activators without thrombin-like action. In contrast, the venom of newborn B. cotiara possessed the highest thrombin-like activity whereas a B. jararacussu adult female did not posses any procoagulant activity. An extremely high procoagulant activity of the venom of newborn Bothrops specimens was demonstrated.

Animals↗