Genome-wide identification and divergent transcriptional expression of StAR-related lipid transfer (START) genes in teleosts

Abstract

The lipid transfer reactions and the steroidogenic acute regulatory protein (StAR)-related lipid transfer (START) genes have a major role in lipid metabolism. However, START genes and their physiological functions in teleost fishes are relatively unknown. Through genome-wide screening, we identified and annotated 91 START genes in 5 teleost species. Although START domain-containing proteins are augmented in teleost genomes relative to tetrapod genomes, a similar number of genes are shared between them. Asymmetry of paralogous gene loss within the teleost START family and an extra copy of some START genes in teleosts resulting from fish-specific genome duplication have been demonstrated. A distinct transcriptional expression pattern within members of some START groups under different developmental stages suggests divergent functions within the same group in the developmental process. In addition, an asymmetric molecular evolution rate deviating from the neutral expectation has been observed in 7 of 14 teleost fish extra-duplicated pairs. The present study provides valuable information for increasing our understanding of the evolution and gene expression divergence under developmental stages of the START gene family in teleost fishes.