Sea Snake Enhydrina Schistosa Research Articles

In vitro antibacterial activity of venom protein isolated from sea snake Enhydrina schistosa against drug- resistant human pathogenic bacterial strains

In vitro antibacterial activity of venom protein isolated from sea snake Enhydrina schistosa against drug- resistant human pathogenic bacterial strains

Molecular evidence that the deadliest sea snake Enhydrina schistosa (Elapidae: Hydrophiinae) consists of two convergent species

We present a striking case of phenotypic convergence within the speciose and taxonomically unstable Hydrophis group of viviparous sea snakes. Enhydrina schistosa, the ‘beaked sea snake’, is abundant in coastal and inshore habitats throughout the Asian and Australian regions, where it is responsible for the large majority of recorded deaths and injuries from sea snake bites. Analyses of five independent mitochondrial and nuclear loci for populations spanning Australia, Indonesia and Sri Lanka indicate that this ‘species’ actually consists of two distinct lineages in Asia and Australia that are not closest relatives. As a result, Australian “E. schistosa” are elevated to species status and provisionally referred to Enhydrinazweifeli. Convergence in the characteristic ‘beaked’ morphology of these species is probably associated with the wide gape required to accommodate their spiny prey. Our findings have important implications for snake bite management in light of the medical importance of beaked sea snakes and the fact that the only sea snake anti-venom available is raised against Malaysian E. schistosa.

A massive infestation of sea snakes by cymothoid isopods

In this study, a massive infestation of the sea snake Enhydrina schistosa by the cymothoid isopod Nerocila serra, commonly parasitizing fishes, is reported for the first time from India. This isopod was found attached on the different parts of the body of the snake. According to the month, the parasitic prevalence ranged from 30.8 to 55.3%, increasing during the monsson period. It was higher in female than in male snakes.

Acidic phospholipases A 2 from the venom of common sea snake enhydrina schistosa

Two acidic phospholipases A have been purified from the venom of common sea snake ( Enhydrina schistosa) by chromatography on Sephadex G-75 gel media, Bio-Rex 70 ion-exchanger followed by repeated Chromatography on DEAE-Sephadex A-25 ion-exchanger. The two preparations were shown to be homogeneous by polyacrylamide gel electrophoresis and ion-exchange chromatography. The enzymes were shown to be specific for the ‘two’ position of egg yolk lecithin. The molecular weight of both enzymes determined by gel filtration chromatography and SDS-polyacrylamide gel electrophoresis was approx. 14000. Both enzymes were non-lethal. Amino acid composition data indicated high contents of aspartic acid, glycine and alamine in both enzymes.

Isolation and characterisation of toxic components from the venom of the common Indian sea snake ( Enhydrina schistosa)

Three neurotoxic components, enhydrotoxins a, b and c, were isolated by a three step procedure from the venom of the sea snake Enhydrina schistosa, caught in the Arabian sea. The i.v. ld 50 values in mice were 0.042, 0.045 and 0.052 mg/kg, respectively. All three toxins irreversibly blocked neuromuscular transmission. Abolition of responses to acetylcholine indicated a post-synaptic site of action of these toxins. The molecular weight and amino acid composition of enhydrotoxin a are similar to values earlier reported for Enhydrina toxins.

Isolation and characterization of a lethal myotoxic phospholipase a from the venom of the common sea snake Enhydrina schistosa causing myoglobinuria in mice

A strongly myotoxic phospholipase A was isolated from the venom of Enhydrina schistosa by gel filtration on Sephadex G-75 and ion exchange chromatography on Bio-Rex 70. The myotoxin is a basic protein containing 120 amino acid residues and seven disulfide bridges. The formula weight is 13,500. The release of myoglobin diagnostic of muscle necrosis was monitored by placing injected mice on sheets of white paper. Affected mice stained the paper red. The myotoxin has an acute ld 50 of 110 μg/kg and causes myoglobinuria at doses down to 30 μg/kg. The molecule lacks trytophan, indicating that this amino acid is not required either for toxicity or catalytic activity. A single histidine residue was modified by reaction with p-bromophenacyl bromide, resulting in > 99% loss of enzymatic and toxic activities. The N-terminal sequence shows homology with nontoxic and neurotoxic phospholipases A 2 of vertebrate origin. The myotoxicity may be of greater clinical importance than the curarimimetic toxins that have received so much attention heretofore.