Impact of photoperiod and sexual maturation on growth performance of Atlantic cod - a genomic perspective

-

Production of cod in aquaculture has seen a notable increase since 2000 and it is poised to expand, as wild cod stocks are at record low levels. Norway is the main cod producer worldwide but profitability of the industry is restricted by the reduction in growth associated with premature sexual maturation. This adds to production time, resulting in significant economic losses. In order to address this serious bottleneck we need to understand the molecular basis of muscle growth in cod but at the moment our knowledge in this area is very limited. We propose to identify the networks of genes that regulate growth in cod and to investigate how they are influenced by light and sexual maturation. The first step is to obtain the tools required for this study. In addition to a microarray chip, we will clone the cod key genes involved in muscle growth, development and biological rhythms. This molecular toolbox will then be used to examine the expression of over 5000 genes in response to light manipulation, to help us understand how it can have a direct influence on growth. We will also investigate expression changes during a whole maturation cycle, in order to identify genes involved in the growth impairment associated with maturation. Data from these large-scale g ene expression studies will be integrated with muscle growth patterns at a cellular level. The most promising candidate genes identified above will be further characterized. In particular, we will look at their expression in response to sex steroids, whic h are known to be present at high levels during maturation. Finally, we will examine the potential use of different light sources to control maturation in aquaculture conditions and their effect on expression of selected genes and muscle growth. This proj ect has potential applications in cod farming, since it may identify growth markers for selective breeding programmes and new targets to minimise the negative impact of maturation on growth performance.