INTRASPECIFIC VARIABILITY IN SNAKE VENOMS

Abrão, D.O.(1), Chavez-Olórtegui, C.(2), Velarde, D.T.(1)

(1)Divisão de Imunobiológicos and (2)Centro de Pesquisas, Fundação Ezequiel Dias, Belo Horizonte, MG, Brazil.

Objectives .- There are statements in the literature about variability in snake venoms but little data. The variabilities described involve difference occuring between wild and captive snakes, snake sizes, seasonal variation and geographical origins. The objective of this work was the systematic study of the real variation exhibited by the venoms of snakes when in captivity.

Methods .- Using Crotalus durissus terríficus snakes as a model we worked with ten adult specimens coming from different regions of Minas Gerais State. After physical identifications their inicial (wild) venoms were collected. Periodically during the following year the snakes were weighed, milked and fed, in this order. The venoms were studied in terms of appearance, weight, proteins and crotamine contents measured by biological assay, Elisa and SDS-PAGE and lethality by

LD-50 in mice.

Results .-1)- One of the specimens did not feed during the observation year, but despite this showed very little loss of weight and venom productivity. 2)- Only one of the wild venoms showed difference in protein contents 3)- All the snake venoms were white except one which was yellow. 4)- After a year in captivity one snake changed its venom color to yellow. 5)- Only six specimens produced venoms containing crotamine. 6)-The LD-50 amplitude varied from 6.34 to 15.52 ug/ mouse. Some of the specimen venoms presented positive and negative variations in lethality during the course of the year.

Conclusions .- The changes exhibited by snake venoms during the prolonged period in captivity are important data, The variability could be intraspecies and even intraspecimen according to the snakes environment.

Supported by: FAPEMIG, FUNED

CORRESPONDENCE TO:

Velarde, D.T., Divisão de Imunobiológicos, Fundação Ezequiel Dias, Conde Pereira Carneiro 80, 03550-010, Belo Horizonte, MG, Brazil, Email: davtovel@funed.mg.gov.br