Discipline: Biological Sciences
Christopher Wellman - University of the District of Columbia
Co-Author(s): Carolyn Cousin and Matty Knight
Biomphalaria glabrata is a tropical freshwater mollusk found in streams, ponds, marshes and rivers throughout South America and the Caribbean islands. B. glabrata is also the intermediate host to the parasite Schistosoma mansoni. This helminth, is one of the parasites in the genus Schistosoma that causes the tropical disease, Schistosomaisis, a disease that infects at least 200 million people a year in over 70 countries world-wide. In the laboratory, we use a strain of B. glabrata called BS-90 that is naturally resistant to S. mansoni. In the resistant snail, the parasite is quickly encapsulated by hemocytes, the cellular component of the snail’s innate defense system, soon after infection, before it is able to enter into the intramolluscan mother sporocyst stage of its life cycle. PIWI the acronym for P-element wimpy testes or HIWI (Human element wimpy testes) is the largest class of small non-coding RNA molecules expressed in animal cells. The function of PIWI is to silence mobile genetic elements, transposons and retrotransposons that could cause mutations and even alter the size of the genome. Resistance in the BS90 snail is a temperature dependent trait, and snails that are maintained at elevated temperature of 32˚C become susceptible to S. mansoni infection. Comparative analysis of the RNA sequence (RNAseq) data from 2 hours infected BS90 snails maintained either at permissive (32˚C) or non- permissive (25˚C) showed that PIWI RNA is down regulated (3- fold) when the BS90 snail is resistant. On the basis of these data, we hypothesize that by using PIWI siRNA to silence PIWI RNA in the resistant BS-90 snail , these snails will become susceptible to the parasite.
Funder Acknowledgement(s): NIH grant 5R25CA129035-04
Faculty Advisor: Freddie Dixon,