Androgen receptor α peak expression in retina rather than gonad of Hainan medaka, Oryzias curvinotus

Abstract

Androgen is a member of the sex steroid hormones family which plays an important role in the development and maturation of the vertebrate reproductive system. The physiological function of androgens is mainly mediated by the androgen receptor (AR). Oryzias curvinotus is a small oviparous fish and a potential model like its sister specie, Oryzias latipes. In this study, two subtypes (α and β) of androgen receptors (ar) genes of O. curvinotus were successfully cloned. Phylogenetic analysis with amino acids showed that arα originates later and differentiates more than arβ. The result of RT-qPCR showed that there were significant differences in the different development stages and different tissues in the expression of two subtypes of ar. Arα remained highly expressed from the eyed stage to the hatching stage, while arβ was lowly expressed. Also, arα was highly expressed in the eyes, liver, and gonads of adults, while arβ remained highly expressed only in adult ovaries. And the result of in situ hybridization confirmed the high expression of arα on the inner nuclear layer of the retina of adult O. curvinotus. Conclusively, the expression and the localization of arα indicated that it plays an important role in both early embryonic development and the eyes of adult O. curvinotus. Further research to enhance the understanding of the new function and mechanism of androgen receptors in medaka is needed.