Differential tissue-regulation of myostatin genes in the teleost fish Lates calcarifer in response to fasting. Evidence for functional differentiation.

Gene or genome duplication is a fundamental evolutionary mechanism leading towards the origin of new genes, or gene functions. Myostatin (MSTN) is a negative regulator of muscle growth that in teleost fish, as a result of genome duplication, is present in double copy. This study provides evidence of differentiation of MSTN paralogs in fish by comparatively exploring their tissue-regulation in the Asian sea bass (Lates calcarifer) when subjected to fasting stress. Results showed differential regulation as well as specific tissue-responses in the muscle, liver, gill and brain of L. calcarifer after nutritional deprivation. In particular, the LcMstn-1 expression increased in liver (∼4 fold) and muscle (∼3 fold) and diminished in brain (∼0.5 fold) and gill (∼0.5 fold) while that of LcMstn-2 remained stable in brain and muscle and was up regulated in gill (∼2.5 fold) and liver (∼2 fold). Differential regulation of Mstn paralogs was supported by in silico analyses of regulatory motifs that revealed, at least in the immediate region upstream the genes, a differentiation between Mstn-1 and Mstn-2. The Mstn-1 in particular showed a significantly higher conservation of regulatory sites among teleost species compared to its paralog indicating that this gene might have a highly conserved function in the taxon.