Selection for cadmium-tolerance in biomphalaria alexandrina snails charactarization based on genetic studies, and susceptibility to schistosoma mansoni association

الملخص EN

Biomphalaria alexandrina snails were examined for their tolerance to cadmium (Cd) toxicity through three generations produced by self-fertilization by exposing snails to serial concentrations of Cd and selection for the most tolerant ones through the successive generations.

Results showed a gradual increase in the LC50 & LC90 values via successive generations indicating tolerance upgrading phenotype.

Also, the selected and non-selected snails were examined for susceptibility to Schistosoma mansoni and hematological criteria.

B.

alexandrina showed refractory tendency with significant increase in hemocytes; granulocytes; indicating that defense mechanism was stronger than other ones.

The dendro-gram based on the similarity matrices of ISSR-PCR banding patterns resulted with ten random primers, showed that the selected groups of the 1st and 2nd generations were the most similar and clustered together forming a distinct group that in turn cluster with nonselected laboratory group that in turn cluster with parent group (field, non-selected), while the 3rd selected generation was the most divergent group, indicating its genetic drift.

The mating system and selection succeeded in evolution of Cd tolerance snail isolate; characterized genetically, physiologically, showed refractory tendency to S.

mansoni infection