Plant & Animal Genomes XVI Conference

January 12-16, 2008
Town & Country Convention Center
San Diego, CA

Heat Shock-Responsive Genes Identified And Validated In Atlantic Cod (Gadus morhua) Using Genomic Techniques.

Tiago S. Hori¹ , Jennifer Kimball² , Stewart C. Johnson² , Luis O. Afonso² , Sharen Bowman³ , Sophie Hubert³ , A. Kurt Gamperl¹ , Matthew L. Rise¹

¹  Ocean Sciences Center, Memorial University of Newfoundland, St John’s, NL, A1C 5S7, Canada

²  Institute for Marine Biosciences, National Research Council of Canada, 1141 Oxford Street, Halifax, NS, B3H 3Z1, Canada

³  The Atlantic Genome Centre, Halifax, NS, B3H 3Z1 Canada

To identify genes and molecular pathways involved in cod responses to acute heat stress, we built and characterized three sets of reciprocal Suppressive Subtractive Hybridization (SSH) cDNA libraries enriched for heat shock-responsive genes. Samples of liver, head kidney, and skeletal muscle from fish submitted to heat shock (HS: transfer from 10ºC to 18ºC for 3 hours) were subtracted against those from control fish (transferred to a tank at 10°C). Plasma cortisol levels increased in both groups after transfer, with levels in heat-shocked fish approximately twice as high as those in control fish. We generated a total of 3677 ESTs from the three forward SSH libraries (enriched for genes up-regulated by heat shock), and 1262 ESTs from the liver reverse SSH library (enriched for genes down-regulated by heat shock). EST contiguous sequences from these libraries had functional annotations including: RNA and protein metabolism, amino acid and carbohydrate metabolism and transport, lipid metabolism, protein folding, and signal transduction pathways. Quantitative reverse transcription – polymerase chain reaction (QPCR) results showed that some chaperone genes were up-regulated by heat shock, including GRP78, Gp96, HSP47, HSP71 and HSP90α. This contradicts reports that suggest that cod do not express HSP71 in response to heat stress. Thus, chaperones and other genes identified to be responsive to heat stress may be candidates for marker-assisted selection (MAS) of heat stress-resistant cod. Stocks of cod resistant to heat stress would be of great value to the aquaculture industry as temperatures within sea cages do approach their thermal maximum.