LE3 .A278 2009

2009

Stewart, Don

Acadia University

Bachelor of Science

Honours

Biology

Biology

The Northern short-tailed shrew, Blarina brevicauda Say, 1823, possesses neurotoxic saliva. Recently two proteins that are putatively responsible for its paralytic effects have been isolated and sequenced. These are referred to as Blarina Toxin (BLTX) and Soricidin. Currently five other groups within the order Insectivora are suspected of possessing salivary toxins that may elicit similar reactions; however, only Blarina has been studied at the molecular level. Three of these additional species belong to the Soricinae subfamily of shrews. Based on the theory of parsimony, it is hypothesized that other species within the same subfamily should exhibit the trait as well. To date, the masked shrew, Sorex cinereus Kerr, 1792, has shown the most promising evidence in demonstrating toxic saliva; however, these properties have not been confirmed or characterized in any detail. Since toxins in many species co-evolve in concert with either predators or prey, demonstrating neurotoxic properties of suspected compounds may not be straightforward. This project has focused on two methods of characterizing salivary toxins from Sorex cinereus. The first method consisted of preparing crude salivary gland extracts and injecting them into adult darkling beetles, Tenebrio molitor Linnaeus, 1758, to monitor for signs of paralysis. The second method involved developing degenerate primers to amplify and sequence the genes that code for the peptides of the toxic salivary proteins. Injections of crude salivary gland extracts from Sorex cinereus did not elicit any obvious signs of paralysis in insects. PCR amplification using degenerate primers resulted in amplification of DNA fragments of expected sizes for both Soricidin and BLTX, however, attempts to sequence these amplicons were unsuccessful. Due to the lack of concrete data for the characterization of the toxic properties in Sorex shrews, further analyses of these genes are recommended.

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https://scholar.acadiau.ca/islandora/object/theses:596