Determination of allozyme, protein and schistosome susceptibility in biomphalaria alexandrina progenies produced by self and cross fertilization

The mating system of B. alexandrina was studied under laboratory condition by allozyme analysis and SDS-PAGE protein analysis for parent snails and their progenies of two successive generations produced by self and cross fertilization. Allozyme analysis detected 11 genetic loci in 3 enzymes; ACP [3 loci], LDH [2 loci] and EST [6 loci]. The mean number of Allele [A], average heterozygosity over loci [H] and dendrogram from cluster analysis based on genetic distances between snail groups showed a genetic heterogeneity in parents and 1[st] generation higher than that in the 2[nd] generation. Cross-fertilization and genetic heterogeneity among snails decreased through generations. Snails practiced self-fertilization showed genetic alterations and genetic heterogeneity was either decreased or increased. SDS-PAGE profile of tissue protein revealed that the mating system in B. alexandrina showed specific bands, 204 and 214 KDa, in snails bred by self-fertilization. D value based on shared protein bands number and estimated similarity between parents and progenies showed that parents were approximately similar with self and cross progenies in 1[st] generation and only with cross progenies in 2[nd] generation as self progenies showed increase or decrease in similarity. B. alexandrina susceptibility to S. mansoni was not affected when snails were bred by cross or self fertilization

In vivo, attenuation of Schistosome cercarial development and disturbance of egg laying capacity in Biomphalaria alexandria using sublethal concentrations of plant molluscicides

The dry powder of Sinapis arvensis, Thymelaea hirsuta, Callistemon lanceolatus and Peganum harmala showed molluscicidal activity against Biomphalaria alexandrina, specific intermediate hosts to Schistosoma mansoni. Effect of LC[25] of dry powdered plant molluscicdes on hexokinase [HK], glucose phosphate isomerase [GPI], AMP deaminase, adenosine deaminase and phenol oxidase [PO] of B. alexandrina was traced. C. lanceolatus showed the highest molluscicidal activity as it has the lowest LC[50] compared to S. arvensis, T. hirsuta, and P. harmala, LC[25] of the latter three plants resulted in more significant inhibition of HK, GPI, AMP deaminase and PO than C. lanceolatus. Treatment of snails with LC[10] of these plants markedly affected compatibility of B. alexandrina to S. mansoni infection. Significant decrease in cercarial production was recorded in snails treated with sublethal concentrations of S. arvensis, T. hirsuta, and P. harmala. Remarkable impairment of the egg laying capacity of molluscicide treated snails was also recorded. Correlation between activity levels of HK, GPI and AMP deaminase and compatibility to parasitic infection and role of PO in the egglaying capacity of these snail species were discussed