Trans-omics analyses revealed differences in hormonal and nutritional status between wild and cultured female Japanese eel (Anguilla japonica)

Abstract

AbstractLong-term stock decline in the Japanese eel (Anguilla japonica) is a serious issue. To reduce natural resource utilization in Japan, artificial hormonal induction of maturation and fertilization in the Japanese eel has been intensively studied. Recent experiment on feminized (by feeding a commercial diet containing estradiol-17β for first half year) cultured eels have shown ovulation problem, which is seldom observed in captured wild eels. In this study, we tried to investigate causes of ovulation problem frequently seen in cultured eels by comparative trans-omics analyses.The omics data showed low growth hormone and luteinizing hormone transcription levels in the brain and low sex hormone–binding globulin transcription levels in the liver of the cultured eels. In addition, we found high accumulation of glucose-6-phosphate and, maltose in the cultured eel liver. We also found that docosahexaenoic (DHA) acid, eicosapentaenoic acid (EPA) and arachidonic acid (ARA) ratios in cultured eels were quite different from wild eels.The data suggested that ovulation problem is due to prolonged intake of a high-carbohydrate diet and/or unbalanced DHA/EPA/ARA ratios in diet.