LE3 .A278 2009

2009

Stewart, Don

Acadia University

Bachelor of Science

Honours

Biology

Biology

The population of masked shrews, Sorex cinereus, found on Bon Portage Island, N.S., has been shown to have a high frequency of a unique allele for the digestive enzyme Peptidase A (PEP A; E.C. 3.4.13.18). As well, these shrews feed upon the amphipod Platorchestia platensis, the sand flea, which is a unique characteristic of this population of shrews. It has been hypothesized that this unique allele for PEP A may be a molecular adaptation to this abundant food source. The goal of this project was to amplify and sequence the unique PEP A allele as well as the common mainland allele. As a first step, known mammalian PEP A sequences were downloaded from the GenBank database and aligned. Seven forward and seven reverse polymerase chain reaction (PCR) primers were designed to amplify different sections of the PEP A gene. Complementary DNA (cDNA) was first generated from RNA using reverse transcription. PCR amplification was conducted with the cDNA using the newly designed primers. Resulting PCR products were then inserted into a plasmid vector and cloned. The purified plasmids were then sequenced at the McGill University and Génome Québec Innovation Center. A search of the GenBank database revealed these sequences were most similar to a segment of DNA within the Sorex araneus genome. Further, the search revealed the PCR amplification product to be highly similar to a Pepsinogen 1 gene as well as a segment of the X chromosome of humans and chimpanzees. The human and chimpanzee X chromosome is homologous to the “de” chromosome in Sorex araneus, which is the chromosomal region to which the PEP A gene has been mapped. A primer specific to the sequenced PCR product was designed and along with a poly T primer the entire gene, possibly PEP A, to which the PCR product belongs was amplified. In summary, these bioinformatic comparisons suggest that this segment could be a portion of a peptidase gene but further analysis will be required to determine precisely which member of the family of peptidase genes has been sequenced.

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https://scholar.acadiau.ca/islandora/object/theses:571