The Potential Role of Nodal in Zebrafish Testis

Abstract

The TGF-β superfamily regulates a range of physiological processes, including development, cell differentiation, and reproduction. While several TGF-β members are well characterized in adult gonadal function, the role of Nodal, a key regulator of early embryogenesis, remains poorly understood in reproduction. This project investigated the potential involvement of Nodal in zebrafish testis physiology. Analysis of offspring from heterozygous ndr1 mutant crosses revealed no significant changes in sex ratio compared to wild-type fish. Gene expression profiling indicated that ndr1 is highly expressed in 9-month-old testis. Ex vivo testis culture with recombinant human Nodal induced time-dependent upregulation of the Nodal inhibitor lft1. RNA-seq analysis of Nodal-treated testis identified modest but coordinated changes in pathways associated with reproductive processes, sperm–egg interactions, cellular organization, and immune response. These findings provide new insight into Nodal pathway activity in the zebrafish testis and lay groundwork for future studies on its role in vertebrate reproductive biology.