Sammendrag
In the last decade there has been a remarkable increase in genomic resources for teleosts, namely whole genome assemblies, expressed sequence tags (ESTs) and microsatellite markers. Nevertheless, the application of these molecular tools to aquaculture and fisheries research is still in its infancy, mostly because of a lack of fundamental knowledge. In particular, we know very little about the genetic networks that regulate muscle growth in fish. In the present study, we have prepared two libraries by suppression subtractive hybridization to compare gene expression profiles between Atlantic salmon (Salmo salar) smolts that showed mosaic hyperplasia and market size fish that were growing mainly by hypertrophy of the existing muscle fibres. We have analysed 3,551 and 4,032 random colonies from the forward and reverse libraries, respectively, which generated more than 3,400 ESTs. These ESTs were then grouped into clusters of putative genes. The 669 and 528 clusters from the forward and reverse libraries, respectively, comprised genes involved in transcription, signalling and cell cycle. We selected 25 genes from each of the libraries and went on to quantify their expression by real-time PCR in various ontogeny stages of Atlantic salmon. This screen identified several candidate genes that might be involved in muscle fibre recruitment, including novel genes of unknown function. In a complementary approach, we are using the 44K salmon microarray from Agilent to examine transcriptomic changes associated with muscle development and growth. The candidate genes discovered in these studies might prove to be useful molecular tools for marker-assisted selection programmes.
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