Master of Science (MSc)
Faculty of Science
Dr. Lucy E. Lee
The cod populations of the Canadian Atlantic were once highly productive, generating enormous annual harvests and attracting fishing fleets from many nations. However, through the late 1980s improved fishing technology, unprecedented capture rates, and poor fishery management brought wild stocks beyond the point of collapse. Dwindling harvests in the early 1990s resulted in cod fishing moratoriums, and an end to the productivity for which the fishery was once renowned. Atlantic cod remains a popular food worldwide and the collapse of cod fisheries has done little to abate market demands. Consequently, the cod is considered a prime candidate for aquaculture production, providing the impetus for commercial-scale farming operations. As aquaculture efforts continue to grow, disease management challenges have become a prominent concern. Many parasites are prevalent on cod farms, including intracellular pathogens such as viruses and microsporidians. Detailed research into diseases affecting farming operations is imperative if commercial-scale cod aquaculture is to develop.
Piscine cell culture techniques represent a valuable tool for studying the intracellular pathogens currently impeding cod aquaculture. To date however, few cell culture models have been made available for the Atlantic cod. This research details the establishment of a larval cod cell line, GML-5, investigations of infective processes in microsporidian parasites, and development of in vitro culture methods for a microsporidian parasite of the Atlantic cod.
GML-5 cells have been cultured for two years and survived more than 26 passages in L-15 media supplemented with 10% fetal bovine serum and incubated at 18°C. The cells have tested positive for a marker of stem cell-like characteristics, had their origin identified as Gadus morhua by DNA barcoding, and been cryopreserved for long-term storage. The cells have been successfully used to support the growth of two microsporidian parasites. Infection-mediating effects of Mg2+ and EDTA have been confirmed in a previously-untested microsporidian species and novel pH treatments were successfully used to stimulate infection and development of Loma morhua in GML-5 cells.
The results of this research represent the foundations of an in vitro infection model for Loma morhua, and demonstrate shared responses to specific chemical conditions by microsporidian parasites with highly dissimilar host species.
MacLeod, Michael J., "In vitro Study of the Microsporidian Parasite Loma morhua, Using Cod-derived Cells and Novel Culture Techniques" (2012). Theses and Dissertations (Comprehensive). Paper 1127.