Assessing Differential Expression of Enzymes in Dermacentor andersoni and Dermacentor variabilis Ticks Following Cold Exposure

Abstract

The survival of overwintering ticks is influenced by several biochemical changes induced by the onset of cold temperatures. Dermacentor andersoni and Dermacentor variabilis ticks are able to increase levels of various biochemical components following cold exposure, however the mechanisms underlying these changes are unknown. This research focused on identifying well- known metabolic enzymes in these ticks in order to establish a mechanism for the increase in metabolites observed following cold exposure. The enzymes explored included glycogen phosphorylase, trehalose-6-phosphate synthase, and phosphofructokinase. As specific nucleotide sequences for each enzyme are not known in D. andersoni or D. variabilis, primers were developed by searching GenBank for homologous sequences in related organisms. RNA to be processed to cDNA was extracted from individual ticks following mechanical homogenization. The resulting cDNA was then subject to PCR using combinations of degenerate primers for each enzyme, and gene products were observed using agarose gel electrophoresis. From the pool of degenerate primers designed for PCR, four primer sets produced promising results. These resulting DNA fragments were excised from the gels to allow for ethanol precipitation of DNA. Following the successful sequencing of the resulting DNA to establish the true sequence amplified, future research will focus on deploying cold treatments to assess if an increase in enzyme expression exists following tick exposure to cold temperatures. This research will reveal potential mechanisms underlying the observed biochemical changes in ticks, as well as provide a comprehensive research design to be used for future studies identifying other genes expressed in cold exposure.

Department: Biological Sciences

Faculty Mentor: Dr. Kevin Friesen