Molecular cloning and tissue expression of the fatty acid-binding protein (Es-FABP9) gene in the reproduction seasons of Chinese mitten crab, Eriocheir sinensis

Fatty acid-binding proteins (FABPs), small cytosolic proteins that function in the uptake and utilization of fatty acids, have been extensively studied in higher vertebrates while invertebrates have received little attention despite similar nutritional requirements during periods of reproductive activity. Therefore, a cDNA encoding Eriocheir sinensis FABP (Es-FABP9) was cloned based upon EST analysis of a testis cDNA library. The full length cDNA was 898 bp and encoded a 136 aa polypeptide that was highly homologous to related genes reported in shrimp. Gene expression analysis, as determined by RT-PCR, revealed the presence of Es-FABP9 transcripts was widely distributed with high and detectable expression levels observed in intestine, ovary, testis and heart, while expression were comparable among hepatopancreas, hemolymphe, gills, muscle, stomach and brain. Real-time quantitative RT-PCR analysis revealed that Es-FABP9 expression in testis, hemolymphe, hepatopancreas and ovarian was dependent on the status of testis development. Evidence provided in the present report supports a role of Es-FABP9 in lipid transport during the period of rapid testis growth in E. sinensis, and indirectly confirms the participation of the hepatopancreas, testis, hemolymphe and ovarian in lipid nutrient absorption and utilization processes.