IDENTIFYING BIOCHEMICAL PATHWAYS USING GENETICALLY MODIFIED TROUT (UNIVERSITY OF CT)
Cool and Cold Water Aquaculture Research
2013 Annual Report
1a.Objectives (from AD-416):
1: Develop homozygous clonal lines of rainbow trout resistant to bacterial and viral pathogens from previously developed transgenic trout. Test disease resistance in outcrosses of different genetic background to evaluate protection.
•1.a. Develop homozygous clonal lines of disease resistant rainbow trout.
•1.b. Identify the expression profiles of genes related to innate immunity and adaptive immunity pathways in homozygous clonal lines of transgenic fish resistant to bacterial, parasitic, and viral infections.
2: Assess whether transgenic rainbow trout resistant to bacterial and viral pathogens are also resistant to infection by parasites (e.g., Ceratomyxa shasta and Myxbolus cerebralis).
3: Develop transgenic rainbow trout capable of accumulating astaxanthin in the flesh and identifying and characterizing factors affecting this trait.
1b.Approach (from AD-416):
With the rapid growth of the human population and the increasing consumption of seafood for health considerations, the world demand for seafood products is mounting rapidly. To this end many countries have turned their attention to various forms of intensive aquaculture production. However, intensive aquaculture has brought about several negative impacts such as increasing disease outbreak incidences and decreasing the quality and nutritional value of fish flesh, resulting in significant economic losses. The application of modern molecular biological technologies including genomics and proteomics will enhance efforts to resolve these problems. We have developed transgenic trout carrying disease resistance genes known as cecropins: these fish exhibit resistance to infection by pathogens affecting aquaculture production including Aeromonas salmonicida and infectious hepatic necrosis virus (IHNV). Using disease resistant transgenic fish and new strains capable of accumulating higher levels of astaxanthin in the flesh as experimental models, we propose to identify and characterize specific pathways and genes leading to increased disease resistance and improved flesh color and nutritional quality. Genes identified from these studies will be characterized for their potential in developing superior broodstock through selective breeding.
By DNA microarray and real-time RT-PCR analyses we have identified many genes in four immune related pathways are upregulated in cecropin transgenic fish. Through repeated sperm-mediated gene transfer trails we have succeeded in producing 8 individuals that crtW and crtZ double transgenes. These fish will reach reproductive maturation by fall 2013. We will establish transgenic founder families in fall 2013 for subsequent characterization. Through challenge studies we have found that progeny of three heterozygous cecropin transgenic families were resistant to infection by Ceratomyxa shasta.