Applications of inter simple sequence repeat (ISSR) rDNA in detecting genetic variations in Lymnaea natalensis snails from certain Egyptian Governorates

Inter-simple sequence repeat (ISSR)-PCR technique was used to assess genetic variation and phylogenetic relationships between Lymnaea natalensis collected from Giza, Ismailia, Damietta, and Beheira governorates in Egypt and compared with lab-bred snail in addition to characterization of watercourses from these sites. Five ISSR primers generated 47 amplified bands, of which 63.63% showed high polymorphism. All tested primers detected the common band (approximately 455 bp) in all L. natalensis studied. Three bands (318, 782 and 2013 bp for primers HB8, HB12 and HB13, respectively) are characteristic for L. natalensis collected from Ismailia, El Behira and Damietta governorates, respectively. These markers were used to estimate genetic similarity among the varieties using Jaccard’s similarity coefficient. The similarity matrix was used to construct a dendrogram. The most abundant snails Physa acuta (56.0%) and the lowest abundant snails Planorbis planorbis, and Melanoides tuberculata (0.5) were found associated with L. natalensis in many governorates. Eichhornia crassipes is the only aquatic plant which grows and is found associated with L. natalensis in all canals of governorates. Also, dragon fly is the only macroinvertebrate collected from all canals, then shrimps and true bugs. Heavy metals were detected in water samples of all tested governorates with different significant differences. In conclusion, the present study used for the first time the ISSR PCR technique for studying genetic variations of L. natalensis snails in Egypt. L. natalensis snails can survive when associated with other snails, plants, and insects and can tolerate the heavy metals in water.Keywords: Lymnaea natalensis, inter-simple sequence repeat (ISSR)-PCR, dendrogram, heavy metals, macroinvertebrates.    

Inheritance of Schistosoma mansoni infection incompatibility in Biomphalaria alexandrina snails

In this study, we looked at the inheritance of susceptibility and resistance to Schistosoma mansoni infection in the first generation of crossbred Biomphalaria alexandrina snails. Our ultimate goal is to use such information to develop a biological method of controlling schistosomiasis. We infected laboratory-bred snails with S. mansoni miracidia and examined cercarial shedding to determine susceptibility and resistance. Five parental groups were used: Group I contained 30 susceptible snails, Group II contained 30 resistant snails, Group III contained 15 susceptible and 15 resistant snails, Group IV contained 27 susceptible and three resistant snails and Group V contained three susceptible and 27 resistant snails. The percentage of resistant snails in the resulting progeny varied according to the ratio of susceptible and resistant parents per group; they are 7%, 100%, 68%, 45% and 97% from Groups I, II, III, IV and V, respectively. On increasing the percentage of resistant parent snails, the percentage of resistant progeny increased, while cercarial production in their susceptible progeny decreased