Snake Venom Tells Tales About Geography

[Chance-reptil-virus 0]

Snake Venom Tells Tales About Geography

ScienceDaily (July 15, 2008) — Just as people give away their origins by that southern drawl or New England twang, poisonous snakes produce venom that differs distinctly from one geographic area to another, the first study of the "snake venomics" of one of the most common pit vipers in Latin America has found.

Scientists are reporting that venom of snakes, such as the Bothrops asper from Costa Rica,
could differ based on geographical regions, an important finding in the production of antivenom.
(Credit: Courtesy of Mahmood Sasa)

In the new study, Juan J. Calvete and colleagues point out that researchers have known for decades that venom collected from snakes of the same species from different geographic locations can differ in terms of their biological effects and symptoms on snakebite victims. However, scientists know little about the chemical differences behind these geographically different venoms.

To find out, the scientists collected venom samples from adult and newborn specimens of the lancehead pitviper from two geographically isolated populations from the Caribbean and Pacific regions of Costa Rica. After a detailed laboratory analysis of the proteins found in the venom -- so-called "snake venomics" -- the researchers found major differences in the venoms collected from the two regions.

They also found distinct differences in proteins collected from newborns and adult snakes. The study "highlights the necessity of using pooled venoms as a statistically representative venom for antivenom production" for human snakebite victims, the report states.


Source : http://www.sciencedaily.com/releases/2008/07/080714092718.htm

[Chance-reptil-virus 0]

Snake Venomics of the Lancehead Pitviper Bothrops asper: Geographic, Individual, and Ontogenetic Variations

Alberto Alape-Girn†‡, Libia Sanz§, Jos Escolano§, Marietta Flores-Daz†, Marvin Madrigal†, Mahmood Sasa† and Juan J. Calvete*§
Instituto Clodomiro Picado, Universidad de Costa Rica, San Jos, Costa Rica, Departamento de Bioqumica, Escuela de Medicina, Universidad de Costa Rica, San Jos, Costa Rica, and Instituto de Biomedicina de Valencia, C.S.I.C., Jaume Roig 11, 46010 Valencia, Spain

Abstract

We report the comparative proteomic characterization of the venoms of adult and newborn specimens of the lancehead pitviper Bothrops asper from two geographically isolated populations from the Caribbean and the Pacific versants of Costa Rica. 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 two B. asper populations, separated since the late Miocene or early Pliocene (8−5 mya) by the Guanacaste Mountain Range, Central Mountain Range, and Talamanca Mountain Range, contain both identical and different (iso)enzymes from the PLA2, serine proteinase, and SVMP families. Using a similarity coefficient, we estimate that the similarity of venom proteins between the two B. asper populations may be around 52%. Compositional differences between venoms among different geographic regions may be due to evolutionary environmental pressure acting on isolated populations. To investigate venom variability among specimens from the two B. asper populations, the reverse-phase HPLC protein profiles of 15 venoms from Caribbean specimens and 11 venoms from snakes from Pacific regions were compared. Within each B. asper geographic populations, all major venom protein families appeared to be subjected to individual variations. The occurrence of intraspecific individual allopatric variability highlights the concept that a species, B. asper in our case, should be considered as a group of metapopulations. Analysis of pooled venoms of neonate specimens from Caribbean and Pacific regions with those of adult snakes from the same geographical habitat revealed prominent ontogenetic changes in both geographical populations. Major ontogenetic changes appear to be a shift from a PIII-SVMP-rich to a PI-SVMP-rich venom and the secretion in adults of a distinct set of PLA2 molecules than in the neonates. In addition, the ontogenetic venom composition shift results in increasing venom complexity, indicating that the requirement for the venom to immobilize prey and initiate digestion may change with the size (age) of the snake. Besides ecological and taxonomical implications, the geographical venom variability reported here may have an impact in the treatment of bite victims and in the selection of specimens for antivenom production. The occurrence of intraspecies variability in the biochemical composition and symptomatology after envenomation by snakes from different gegraphical location and age has long been apreciated by herpetologist and toxinologists, though detailed comparative proteomic analysis are scarce. Our study represents the first detailed characterization of individual and ontogenetic venom protein profile variations in two geographical isolated B. asper populations, and highlights the necessity of using pooled venoms as a statistically representative venom for antivenom production.


Source : http://pubs.acs.org/doi/abs/10.1021/pr800332p

[crowley 0]

Ce n'est pas une nouveauté en ce qui concerne les différences de composition du venin entre les jeunes et les adultes, ça semble même logique, puisque bien souvent le régime alimentaire évolue au cours de la vie de l'animal, besoin d'ajustement pour une efficacité optimum.

En ce qui concerne les différences dues à la localité, quand on voit les différences morphologiques et de livrées déjà entre individus d'une même espèce, qui par définition, se caractérise par un isolement génétique... c'est uniquement l'expression de gènes identiques qui diffère, alors pourquoi pas une expression différente dans la composition du venin?

effectivement les "pooled venoms" se fond très souvent dans la récolte de venin, la mise en commun de ces différents venins ne peut être qu'un plus!