Dataset Information

Postsynaptic alpha-neurotoxin gene of the spitting cobra, Naja naja sputatrix: structure, organization, and phylogenetic analysis.

ABSTRACT: The venom of the spitting cobra, Naja naja sputatrix contains highly potent alpha-neurotoxins (NTXs) in addition to phospholipase A2 (PLA2) and cardiotoxin (CTX). In this study, we report the complete characterization of three genes that are responsible for the synthesis of three isoforms of alpha-NTX in the venom of a single spitting cobra. DNA amplification by long-distance polymerase chain reaction (LD-PCR) and genome walking have provided information on the gene structure including their promoter and 5' and 3' UTRs. Each NTX isoform is approximately 4 kb in size and contains three exons and two introns. The sequence homology among these isoforms was found to be 99%. Two possible transcription sites were identified by primer extension analysis and they corresponded to the adenine (A) nucleotide at positions +1 and -45. The promoter also contains two TATA boxes and a CCAAT box. Putative binding sites for transcriptional factors AP-2 and GATA are also present. The high percentage of similarity observed among the NTX gene isoforms of N. n. sputatrix as well as with the alpha-NTX and kappa-NTX genes from other land snakes suggests that the NTX gene has probably evolved from a common ancestral gene.

SUBMITTER: Afifiyan F

PROVIDER: S-EPMC310718 | biostudies-literature | 1999 Mar

REPOSITORIES: biostudies-literature

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Postsynaptic alpha-neurotoxin gene of the spitting cobra, Naja naja sputatrix: structure, organization, and phylogenetic analysis.

Afifiyan F F Armugam A A Tan C H CH Gopalakrishnakone P P Jeyaseelan K K

Genome research 19990301 3

The venom of the spitting cobra, Naja naja sputatrix contains highly potent alpha-neurotoxins (NTXs) in addition to phospholipase A2 (PLA2) and cardiotoxin (CTX). In this study, we report the complete characterization of three genes that are responsible for the synthesis of three isoforms of alpha-NTX in the venom of a single spitting cobra. DNA amplification by long-distance polymerase chain reaction (LD-PCR) and genome walking have provided information on the gene structure including their pro ...[more]

PMID: 10077532

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Project description:BackgroundThe optimization of snakebite management and the use of antivenom depend greatly on the knowledge of the venom's composition as well as its pharmacokinetics. To date, however, pharmacokinetic reports on cobra venoms and their toxins are still relatively limited. In the present study, we investigated the pharmacokinetics of Naja sumatrana (Equatorial spitting cobra) venom and its major toxins (phospholipase A2, neurotoxin and cardiotoxin), following intravenous and intramuscular administration into rabbits.Principal findingsThe serum antigen concentration-time profile of the N. sumatrana venom and its major toxins injected intravenously fitted a two-compartment model of pharmacokinetics. The systemic clearance (91.3 ml/h), terminal phase half-life (13.6 h) and systemic bioavailability (41.9%) of N. sumatrana venom injected intramuscularly were similar to those of N. sputatrix venom determined in an earlier study. The venom neurotoxin and cardiotoxin reached their peak concentrations within 30 min following intramuscular injection, relatively faster than the phospholipase A2 and whole venom (Tmax=2 h and 1 h, respectively). Rapid absorption of the neurotoxin and cardiotoxin from the injection site into systemic circulation indicates fast onsets of action of these principal toxins that are responsible for the early systemic manifestation of envenoming. The more prominent role of the neurotoxin in N. sumatrana systemic envenoming is further supported by its significantly higher intramuscular bioavailability (Fi.m.=81.5%) compared to that of the phospholipase A2 (Fi.m.=68.6%) or cardiotoxin (Fi.m.=45.6%). The incomplete absorption of the phospholipase A2 and cardiotoxin may infer the toxins' affinities for tissues at the injection site and their pathological roles in local tissue damages through synergistic interactions.Conclusion/significanceOur results suggest that the venom neurotoxin is absorbed very rapidly and has the highest bioavailability following intramuscular injection, supporting its role as the principal toxin in systemic envenoming.

Project description:Objectives:The objective of the present work was to examine the bacterial flora associated with the oral cavity of Indian cobra and to study their antibiogram. Methods:Oral swabs, collected from six healthy (4 males and 2 females) adult cobra, were subjected to microbiological examination through differential media. A total of 74 isolates which demonstrated noticeable colony characters were studied with different biochemical tests. The strains that showed distinctive colonies, morphology and biochemical parameters were additionally subjected to phylogenetic characterization using 16S rRNA gene sequences. Further, the isolates were subjected to antimicrobial susceptibility testing using ICOSA-20-plus and ICOSA-20-minus. Results:Microscopic examination of the oral cavity of Indian cobra revealed the dominance of Gram-negative bacteria over Gram-positive. The oral microflora constituted of bacteria such as Salmonella sp. (S. typhi, S. paratyphi A); Pseudomonas sp. (P. aeruginosa, P. fluorescence); Proteus sp. (P. mirabilis, P. penneri, P. vulgaris); E. coli; Morganella sp.; Citrobacter sp. (C. diversus, C. freundii); Aeromonas sp. (A. hydrophila, A. salmonicida); Enterobacter sp. (E. aerogens); Acinetobacter sp. (A. baumannii); Neisseria sp.; Serratia sp.; Bacillus sp. (B. cereus, B. megatarium, B. atrophaeus and B. weihenstephanensis); Enterococcus sp. (E. faecalis, E. faecium); Staphylococcus sp. (S. aureus, S. epidermidis); Alcaligenes sp.; Chryseobacterium sp. and Micrococcus sp. Most of the isolates were resistant towards antibiotics such as Penicillin, Cefpodoxime, Amoxyclav, Co-Trimoxazole, Ticarcillin, Erythromycin and Nalidixic acid while sensitive towards Ciprofloxacin, Gentamicin, Ofloxacin, Sparfloxacin, Tobromycin, Ceftriaxone, Tetracycline, Novobiocin and Imipenem. Conclusions:The secondary complications of the snake bite victims should be managed with appropriate antibiotics after proper examination of the bacterial flora from the wound sites.

Dataset Information

Postsynaptic alpha-neurotoxin gene of the spitting cobra, Naja naja sputatrix: structure, organization, and phylogenetic analysis.

Publications

Postsynaptic alpha-neurotoxin gene of the spitting cobra, Naja naja sputatrix: structure, organization, and phylogenetic analysis.

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