RESUMO
Enzyme electrophoresis of extracts prepared from snails collected from five different localities in Egypt and their progenies through the successive generations, were stained for acid phosphatase [ACP], exhibited mainly three electrophoresis patterns. The first which presented with three bands [R[f] 33+/1, 27 +/- and 23+/1], the second with two bands [R[f]33+/1 and 23+/1] and the third with one band [R[f] 23+/1]. In order to examine the relation of ACP henotypes with susceptibility or refractory characters to Schistosoma mansoni infection in B. alexandrina, the percentage of these phenotypes were calculated and compared among susceptible and non-susceptible snails. There was no correlation between ACP henotypes and the susceptibility of snails from different populations, and the percentage of the pattern two of ACP [exapressign resistance to schistosome infection] was approximately the same in susceptible and non-susceptible snails. Polymorphism of ACP patterns observed in the field snails and their first generation began to decrease through generations in both susceptible and non-susceptible snails and the one-banded pattern became predominant