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Papers by ahmed Sharaf Eldin

Research paper thumbnail of The relationship between genetic variability and the susceptibility of Biomphalaria alexandrina snails to Schistosoma mansoni infection

Memórias do Instituto …, Jan 1, 2012

In the present study, Biomphalaria snails collected from five Egyptian governorates (Giza, Fayoum... more In the present study, Biomphalaria snails collected from five Egyptian governorates (Giza, Fayoum, Kafr El-Sheikh, Ismailia and Damietta), as well as reference control Biomphalaria alexandrina snails from the Schistosome Biological Supply Center (SBSC) (Theodor Bilharz Research Institute, Egypt), were subjected to species-specific polymerase chain reaction (PCR) assays to identify the collected species. All of the collected snails were found to be B. alexandrina and there was no evidence of the presence of Biomphalaria glabrata. Randomly amplified polymorphic DNA (RAPD)-PCR assays showed different fingerprints with varying numbers of bands for the first generation (F1) of B. alexandrina snail populations (SBSC, Giza, Fayoum, Kafr El-Sheikh, Ismailia and Damietta). The primer OPA-1 produced the highest level of polymorphism and amplified the greatest number of specific bands. The estimated similarity coefficients among the B. alexandrina populations based on the RAPD-PCR profiles ranged from 0.56 (between SBSC and Ismailia snails) to 0.72 (between Ismailia and Kafr El-Sheikh snails). Experimental infection of the F1 of progeny from the collected snails with Schistosoma mansoni (SBSC strain) showed variable susceptibility rates ranging from 15% in the Fayoum snail group to 50.3% in SBSC snails. A negative correlation was observed between the infection rates in the different snail groups and the distances separating their corresponding governorates from the parasite source. The infection rates of the snail groups and their similarity coefficients with SBSC B. alexandrina snails were positively correlated. The variations in the rates of infection of different B. alexandrina groups with S. mansoni, as well as the differences in the similarity coefficients among these snails, are dependent not only on the geographical distribution of the snails and the parasite, but also on the genetic variability of the snails. Introduction of this variability into endemic areas may reduce the ability of the parasite to infect local hosts and consequently reduce schistosomiasis epidemiology.

Research paper thumbnail of Effect of ethanolic extract of Dalbergia sissoo plant parts on Biomphalaria alexandrina snail, the intermediate host of Schistosoma mansoni

academicjournals.org

Dalbergia sissoo (family Leguminosae) fruits, leaves, roots and stem bark against adult Biomphala... more Dalbergia sissoo (family Leguminosae) fruits, leaves, roots and stem bark against adult Biomphalaria alexandrina, the snail intermediate host of Schistosoma mansoni in Egypt and their egg masses. Adult snails (6 to 8 mm in diameter) and viable 24 h-old embryonated egg masses were separately exposed to seven different concentrations (6.25 to 400 ppm) of extracts for 24 h. The LC 50 and LC 90 values of test extracts for adult snails and egg masses were calculated by probit analysis. The activities of the tested extracts were concentration-dependent. However, only the ethanolic extract of the fruits demonstrated significant activity on both adult snails and egg masses (24 h-LC 90 value 34.4 and 38.6 ppm, respectively). Mortalities of eggs were manifested at the gastrula/exogastrula and or the pre-hatch snail stage of development. Ethanolic extract of the fruits was the most active with 100% mortality at 50 mg/l, followed by those of the leaves (at 100 mg/l), roots (at 200 mg/l) and stem bark (at 400 mg/l). Their respective 24 h-LC 50 and LC 90 values for B. alexandrina egg masses were 10.8 and 38.6 ppm, 18.5 and 68.3 ppm, 20.4 and 88.4 ppm, 36.8 and 144.6 ppm. The percentage of dead embryos at all stages increased with increasing concentration of extract. Lethality of the ethanolic extract of D. sissoo fruits to embryonated egg masses of B. alexandrina is an added advantage to its potential development for use as a plant molluscicide, as the overall efficacy of a molluscicide is greatly enhanced if it also shows significant toxicity towards snail eggs.

Research paper thumbnail of Tissue responses exhibited by< i> Biomphalaria alexandrina</i> snails from different Egyptian localities following< i> Schistosoma mansoni</i> exposure

Experimental …, Jan 1, 2011

The user has requested enhancement of the downloaded file. All in-text references underlined in b... more The user has requested enhancement of the downloaded file. All in-text references underlined in blue are added to the original document and are linked to publications on ResearchGate, letting you access and read them immediately. This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.

Research paper thumbnail of The relationship between genetic variability and the susceptibility of Biomphalaria alexandrina snails to Schistosoma mansoni infection

Memórias do Instituto …, Jan 1, 2012

In the present study, Biomphalaria snails collected from five Egyptian governorates (Giza, Fayoum... more In the present study, Biomphalaria snails collected from five Egyptian governorates (Giza, Fayoum, Kafr El-Sheikh, Ismailia and Damietta), as well as reference control Biomphalaria alexandrina snails from the Schistosome Biological Supply Center (SBSC) (Theodor Bilharz Research Institute, Egypt), were subjected to species-specific polymerase chain reaction (PCR) assays to identify the collected species. All of the collected snails were found to be B. alexandrina and there was no evidence of the presence of Biomphalaria glabrata. Randomly amplified polymorphic DNA (RAPD)-PCR assays showed different fingerprints with varying numbers of bands for the first generation (F1) of B. alexandrina snail populations (SBSC, Giza, Fayoum, Kafr El-Sheikh, Ismailia and Damietta). The primer OPA-1 produced the highest level of polymorphism and amplified the greatest number of specific bands. The estimated similarity coefficients among the B. alexandrina populations based on the RAPD-PCR profiles ranged from 0.56 (between SBSC and Ismailia snails) to 0.72 (between Ismailia and Kafr El-Sheikh snails). Experimental infection of the F1 of progeny from the collected snails with Schistosoma mansoni (SBSC strain) showed variable susceptibility rates ranging from 15% in the Fayoum snail group to 50.3% in SBSC snails. A negative correlation was observed between the infection rates in the different snail groups and the distances separating their corresponding governorates from the parasite source. The infection rates of the snail groups and their similarity coefficients with SBSC B. alexandrina snails were positively correlated. The variations in the rates of infection of different B. alexandrina groups with S. mansoni, as well as the differences in the similarity coefficients among these snails, are dependent not only on the geographical distribution of the snails and the parasite, but also on the genetic variability of the snails. Introduction of this variability into endemic areas may reduce the ability of the parasite to infect local hosts and consequently reduce schistosomiasis epidemiology.

Research paper thumbnail of Effect of ethanolic extract of Dalbergia sissoo plant parts on Biomphalaria alexandrina snail, the intermediate host of Schistosoma mansoni

academicjournals.org

Dalbergia sissoo (family Leguminosae) fruits, leaves, roots and stem bark against adult Biomphala... more Dalbergia sissoo (family Leguminosae) fruits, leaves, roots and stem bark against adult Biomphalaria alexandrina, the snail intermediate host of Schistosoma mansoni in Egypt and their egg masses. Adult snails (6 to 8 mm in diameter) and viable 24 h-old embryonated egg masses were separately exposed to seven different concentrations (6.25 to 400 ppm) of extracts for 24 h. The LC 50 and LC 90 values of test extracts for adult snails and egg masses were calculated by probit analysis. The activities of the tested extracts were concentration-dependent. However, only the ethanolic extract of the fruits demonstrated significant activity on both adult snails and egg masses (24 h-LC 90 value 34.4 and 38.6 ppm, respectively). Mortalities of eggs were manifested at the gastrula/exogastrula and or the pre-hatch snail stage of development. Ethanolic extract of the fruits was the most active with 100% mortality at 50 mg/l, followed by those of the leaves (at 100 mg/l), roots (at 200 mg/l) and stem bark (at 400 mg/l). Their respective 24 h-LC 50 and LC 90 values for B. alexandrina egg masses were 10.8 and 38.6 ppm, 18.5 and 68.3 ppm, 20.4 and 88.4 ppm, 36.8 and 144.6 ppm. The percentage of dead embryos at all stages increased with increasing concentration of extract. Lethality of the ethanolic extract of D. sissoo fruits to embryonated egg masses of B. alexandrina is an added advantage to its potential development for use as a plant molluscicide, as the overall efficacy of a molluscicide is greatly enhanced if it also shows significant toxicity towards snail eggs.

Research paper thumbnail of Tissue responses exhibited by< i> Biomphalaria alexandrina</i> snails from different Egyptian localities following< i> Schistosoma mansoni</i> exposure

Experimental …, Jan 1, 2011

The user has requested enhancement of the downloaded file. All in-text references underlined in b... more The user has requested enhancement of the downloaded file. All in-text references underlined in blue are added to the original document and are linked to publications on ResearchGate, letting you access and read them immediately. This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.