Major Histocompatibility Complex (MHC)

photo: denaturing gradient gel electrophoresisThe MEGA group led by Dr. Kristi Miller has conducted research on salmonid MHC variation in wild populations for over 10 years. Their research has advanced considerably knowledge of MHC diversity and locus complexity, with manuscripts outlining MHC locus structure in both salmon and Atlantic cod. The large MHC databases developed for coho, sockeye and Chinook salmon have provided the backdrop for studies on molecular adaptation, demonstrating that selection overrides migration and drift in the generation and maintenance of variation at the MHC class II DAB locus in salmon. As well, their research has demonstrated MHC associations with susceptibility to the IHN virus in North American Aquaculture strains of Atlantic salmon, susceptibility to parasites in wild Quebec populations of Atlantic salmon, and bacterial complexity in lakes. Furthermore, MHC diversity, manifested through MHC-based odour recognition systems, is used by juvenile salmon in kin discrimination, resulting in a preferential attraction to kin as juveniles, and potentially to a mechanism used to assure outbreeding in adults. Overall, the research by the MEGA group on adaptive variation in MHC has validated the high functionality of the MHC in salmon that is not only important in our understanding of evolutionary ecology, but also points to possible mechanisms of differential susceptibilities to disease among wild salmon populations and aquaculture strains. Moreover, MHC is one of the most powerful genetic markers routinely applied in salmon management through the genetic stock ID program within the MGL.

  • Sockeye 375 populations, 43,000 individuals
  • Coho 380 populations, 40,000 individuals
  • Chinook 32 populations, 3800 individuals