Using transcriptome analysis to investigate the induction of vitellogenesis in female Japanese eels (Anguilla japonica)

Abstract

Oogenesis, encompassing folliculogenesis, development, and maturation, is a complex physiological process that is not solely regulated by gonadotropins but is also actively influenced by multiple growth factors produced by the oocyte and its surrounding follicular cells. The Japanese eel (Anguilla japonica) has a complex life history, resulting in many uncertainties regarding its growth, development, and reproduction. Under artificial culture conditions, oocyte development in the Japanese eel is arrested and can only progress to the vitellogenic stage through artificial induction. In the present study, we observed that, despite receiving the same hormone treatment as normally developing individuals, a small proportion of female eels exhibited oocytes arrested at the perinucleolar stage. Transcriptome analysis revealed that differentially expressed genes are involved in multiple reproductive-related physiological processes and functional pathways, such as tachykinin system, MAPK signaling pathway, steroid-related pathways, oocyte meiosis, Wnt signaling pathway and GnRH signaling pathway. The abnormal expression of the two follicle-stimulating hormone (FSH) subunit genes may be a key factor contributing to this phenomenon. This study reveals the underlying causes of ovarian developmental arrest in hormonally induced female Japanese eels from the perspective of the brain–pituitary–gonad (BPG) axis, providing a research foundation for the artificial reproduction of Japanese eels.