Stress physiology and immune responses of Atlantic cod (Gadus Morhua) subjected to various challenges

Hori, Tiago S. (2012) Stress physiology and immune responses of Atlantic cod (Gadus Morhua) subjected to various challenges. Doctoral (PhD) thesis, Memorial University of Newfoundland.

[English] PDF (Migrated (PDF/A Conversion) from original format: (application/pdf)) - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (117MB) [English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. (Original Version)

Abstract

The Atlantic cod is an economically important species in Canada, as well as in several European countries including Norway, Iceland and Scotland. However, collapse of Atlantic cod stocks has threatened the global Atlantic cod fishing industry. The aquaculture of Atlantic cod could be an alternative source of fish for these markets, but its establishment has been slow, due to the lack of knowledge with regards to certain aspects of this species' biology (e.g health/disease, optimal diet formulation and early maturation). Therefore, the objectives of this thesis were to develop tools to study the stress physiology and immune function of cod, and to apply these to aquaculture relevant questions. In Chapter 2, I: 1) demonstrated that cortisol responsiveness was negatively correlated with growth parameters; and 2) identified differences in the magnitude of the cortisol stress response to handling and potential quantitative trait loci (QTL) associated with this phenotype. In Chapter 3, I investigated the molecular mechanisms that mediate differences in cortisol responsiveness by measuring the mRNA expression of genes involved in cortisol synthesis and tissue responsiveness in Atlantic cod with different magnitudes of cortisol response. In Chapter 4, I report on a stress relevant gene discovery effort conducted as part of the Atlantic C[barbelow]od G[barbelow]enomics and Broodstock Development P[barbelow]roject (CGP), that involved the sequencing and characterization of over 5000 ESTs. Several of the genes identified in this work were validated using quantitative real-time reverse transcription-polymerase chain reaction (QPCR) as heat shock responsive genes, and were subsequently incorporated into the CGP 20K Atlantic cod microarray. Finally, in Chapter 5, I used this microarray platform to study the effect of a gradual temperature increase (from 10 to 16°C over several weeks) on immune-relevant gene transcription, and demonstrated that these increases in temperature dysregulated the anti-viral transcriptomic response of Atlantic cod; fish held at 16°C responding earlier than Atlantic cod held at 10°C. This research has contributed significantly to the resources available for investigating aquaculture relevant questions in Atlantic cod, and generated novel information that can be used to develop molecular markers for use in Atlantic cod broodstock selection programs.

Actions (login required)

View Item