Spatial Distribution of Ontogenetic Variability in Venoms of Crotalus durissus from Two Ecosystems (Caatinga and Deciduous Forest) of the State of Bahia, Brazil.

^1*Biondi, I.; ¹Soares, W.R.; ²Franca-Rocha, W.; ³Borges, M.H.; ⁴Oliveira, J.S.; ⁵Barbosa Jr., A.; ⁴Santoro, M.M.; ³De Lima, M.E.; ⁶M. Lopes-Ferreira.

1 Lab. de Animais Peçonhentos, DCBIO; 2 Lab. de Geociências, DEXA; 1,2 UEFS, Feira de Santana, Brazil; 3 Lab. de Ven. e Toxinas Animais; 4 Lab. Enzimologia e Físico-Química de Proteínas; Depto. de Bioquímica, 3.4.5 ICB/UFMG Belo Horizonte-MG, Brazil; 5 Lab. de Histopatologia, CPGM/FIOCRUZ, Salvador-BA, Brazil; 6 Laboratory of Immunopathology, Butantan Institute, São Paulo-SP, Brazil.

The study aimed to compare the biochemical, biological and histopathological activities of venoms from Crotalusdirissus populations inhabiting two ecosystems (Caatinga and Deciduous Forest). We performed column gel filtration chromatography (Superose 12 HR10/30), by diluting 7 mg of venom in 1 ml of buffer (pH 7,5). Four peaks were found in the venoms from Caatinga snakes (hereafter CAA-Venom), whereas two peaks were found in the venoms from Deciduous Forest snakes (hereafter FOR-Venom). A gel gradient electrophoresis (SDS- PAGE 5-20%) was run using 25 g of each venom, in order to obtain the electrophoresis profiles. Populations from both ecosystems have in common three groups of protein bands with molecular mass (MM) ranging from 212 to 170 kDa, 170 to116 kDa and 20 to 14 kDa. We detected one band from 53 to 66 kDa, two bands from 36 to 29 kDa, two bands from 20 to 29 kDa and one band from 20 to 14 kDa in CAA-Venom which were not present in FOR-Venom. We found protein bands with MM less than 14 kDa in both populations. Fibrinogen alpha chain degradation was evaluated using 50 l of fibrinogen (1,5mg/ml) incubated with venom doses of 10, 20 and 50 g at 37°C for 5 h. The degradation of fibrinogen was similar in both venoms, except the 10 g dose of FOR-Venom which showed low degradation. In order to determine the clotting activity, 200 l of bovine plasma were incubated with 50, 60, 70, 80, 90 and 100 g of each venom at 37°C. The clotting activity was greater in the CAA-Venom. Regarding crotamine presence, we found it only in CAA-Venom. Systemic disorders such us breathing impairment, itching, circular movements and severe convulsions were very frequent in mice inoculated with FOR-Venom and less frequent in those inoculated with CAA-Venom. Histological analysis (via intraperitoneal) of mice tissues showed that CAA-Venom caused congestion in the central lobe of the liver, cardiac insufficiency, and characterizing thrombosis. Generalized congestion was verified in the kidney, as well as hemorrhage in focal areas. Edema was found between fibers of diaphragm and esophagus. The FOR-Venom caused edema in diaphragm, congestion in the liver and hemorrhage in the kidneys, but always in a discreet manner. Our results show an important variability in the biochemical characteristics as well as in the biological activities of Crotalusdurissus venoms. An analysis of this variability based on the spatial distribution showed an association of the distribution of the population from deciduous forest with high altitudes and indices of rainfall. On the other hand, the population from the caatinga is associated to low altitudes and indices of rainfall. This preliminary analysis indicates that the geomorphologic surfaces where the two populations occur constitute geographic barriers, isolating them in distinct ecosystem units. This study allows relating both biogeography and venom ontogenetic variability to the clinical profile verified in snake accidents in some regions of Bahia, impacting the primary research in this field, as well as the administration of anti-venoms.

Support: UEFS; UFMG/ICB/PRPg

Correspondence to: ibiondi@uefs.br; ibiondi@uol.com.br