Trimeresurus Research Articles

A Phylogeny of the Trimeresurus Group of Pit Vipers: New Evidence from a Mitochondrial Gene Tree

The Trimeresurus group is an important radiation of over 40 Asian pit viper species. Once considered congeneric, four genera are generally currently recognized (Trimeresurus sensu stricto, Ovophis, Protobothrops, and Tropidolaemus) but relationships within and between these are still unclear. This study, based on mitochondrial cytochrome b sequences, is the first to include a large number of species (21) and demonstrates that the current taxonomy does not adequately represent either the relationships or the genetic diversity present in the complex. Although many deeper nodes are not strongly supported, the following novel conclusions are all well supported: (1) the paraphyly of Trimeresurus sensu stricto, (2) the presence of several divergent clades within Trimeresurus sensu stricto, (3) the paraphyly of some widespread, medically significant, species, (4) the nonmonophyly of Ovophis, and (5) the monophyly of Protobothrops. Mapping of morphological characters onto the mitochondrial tree further supports the four groups proposed for Trimeresurus sensu stricto.

Relating geographic pattern to phylogenetic process

Observed patterns of within-species geographic variation may reflect phylogenetic history or ecogenetic adaptation, and it is frequently desirable to evaluate their relative contributions. Phylogenetic information can be recovered from relatively neutrally evolving molecular markers, but to what extent are they useful in understanding the causes of observed geographic patterns within species? In the lacertid lizard Gallotia galloti (Western Canary islands), it allows the colonization sequence to be hypothesized, giving a new perspective on the causes of morphological differentiation between island populations. In South-East Asian pit-vipers, venom evolution can be evaluated in relation to biogeographic processes and current ecology. At a finer geographic scale, alternative historical and geological hypotheses can be tested to explain within-island microgeographic variation in G. galloti in Tenerife. Similar work on Anolis oculatus within the island of Dominica, however, raises questions concerning some of the assumptions behind a molecular phylogenetic approach.

Isolation and characterization of a toxic phospholipase A2 from the venom of the Taiwan habu (Trimeresurus mucrosquamatus).

A toxic phospholipase A2 (PLA2) was isolated from Taiwan-habu-snake (Trimeresurus mucrosquamatus) venom by sequential chromatographies on CM-52, Sephadex G-75 and S-Sepharose columns. This basic PLA2 has a single polypeptide with an estimated M(r) of 15,000. The PLA2 activity was Ca(2+)-dependent and inactivated by p-bromophenacyl bromide and its specific antibody. The toxic PLA2-induced myotoxic and direct haemolytic effects as well as respiratory distress in mice with an intraperitoneal LD50 of 1.17 micrograms/g body weight. The histological examination showed it caused haemorrhage and congestion in the viscera of mice. It was also cytotoxic to myeloma cells (NS-1), baby-hamster-kidney (BHK) cells and human umbilical endothelial cells. By neutralization experiments with a specific antibody against toxic PLA2, it was found that the enzymic activity of toxic PLA2 is essential for its myotoxicity, but it is not the only factor responsible for the lethal toxicity.

要旨ハブの交尾期,繁殖参加雌の割合および性的成熟

要旨ハブの交尾期,繁殖参加雌の割合および性的成熟

Comparative Morphology of Three Strains of Rabies Virions Propagated in the Reptilian Cell Line, VSW

Cell line VSW, derived from the spleen of a tumor-bearing Asian pit viper, spontaneously produces C-type virions budding from membranes, and similar virions that develop within mitochondria. Rabies virus has been determined to replicate more efficiently in VSW cells than in a variety of other cell types cultivated from reptiles, amphibians or fish. We have compared the morphology of three strains (CVS, ERA and HEP) of fixed BHK/21 cell-adapted rabies virus in VSW cells infected at a cell multiplicity of infection of 20 and incubated at 33&C for 8 days prior to fixation.