Molecular basis of stress and immune responses in teleost fish

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Different fish species have characteristic responses to pathogens. For example, Atlantic salmon are susceptible to the viral pathogen causing Infectious Salmon Anaemia (ISA), while other salmonids such as rainbow trout, brown trout, and Arctic char, are resistant to ISA. It is also known that different fish species may respond differently to environmental stress such as increased ambient temperature. The genes and biochemical pathways involved in species-specific differences in fish immune and stress responses are poorly understood. My research program will use the power of genomics to reveal the key genes involved in fish defense against pathogens and environmental stress. This work uses genomic tools such as DNA microarrays (gene chips), which allow the researcher to study the expression of thousands of known genes simultaneously. In addition, because currently available fish microarrays are missing many genes, I will create new genomic resources (subtracted cDNA libraries) for identifying unknown defense response genes. My approach is novel in that it uses parallel exposures of three evolutionarily divergent groups of fish (salmonids, Atlantic cod, and zebrafish) to immunogenic stimuli or environmental stress, followed by gene expression studies with DNA microarrays, subtracted libraries, and other genomic techniques. In addition, the impact of thermal stress during embryonic development will be analyzed for these fish groups. Bioinformatic methods will be used to compare different species' global gene expression responses to a particular stressor, and to identify the molecular pathways represented by immune- or stress-responsive genes. Cross-species comparisons of global gene expression results will identify some genes that are part of all fish defense systems, and other genes that act in lineage-specific defense responses. This research will significantly improve our understanding of how fish protect themselves against pathogens and environmental stress, and will be valuable to several research areas including comparative immunology, evolutionary biology, and aquaculture.