Intraspecific variation of the crotamine and crotasin genes in Crotalus durissus rattlesnakes.

Crotamine is a small basic myotoxin peptide of Crotalus durissus venom, with beta-defensin scafold and variable concentration in individual venoms. The crotamine gene was mapped to the end of chromosome 2 and the signal intensity differed significantly between the two homologues. In contrast to crotamine, the paralogous crotasin gene is scarcely expressed in the venom glands.

Physiological basis for diurnal activity in dispersing juvenile Bufo granulosus in the Caatinga, a Brazilian semi-arid environment.

Diurnal activity is characteristic of many toad species, including Bufo granulosus from the Brazilian semi-arid biome called the Caatinga. Because of their patterns of activity, juvenile toads are exposed to hot and dehydrating conditions. Our investigation focuses on temperature and water relationships, and is based on the prediction that anuran diurnal activity in a semi-arid environment must be associated with morphological, physiological and behavioral traits enhancing thermal tolerances, capacity for performance at high temperatures and water balance.