Sex-biased gene expression precedes sexual dimorphism in the agonadal annelidPlatynereis dumerilii

Abstract

AbstractGametogenesis is the process by which germ cells differentiate into mature sperm and oocytes, cells essential for sexual reproduction. The sex-specific molecular programs that drive spermatogenesis and oogenesis can also serve as sex identification markers.Platynereis dumeriliiis a research organism that has been studied in many areas of developmental biology. However investigations often disregard sex, asP. dumeriliijuveniles lack sexual dimorphism. The molecular mechanisms of gametogenesis in the segmented wormP. dumeriliiare also largely unknown. In this study, we used RNA sequencing to investigate the transcriptomic profiles of gametogenesis inP. dumeriliijuveniles. Our analysis revealed that sex-biased gene expression becomes increasingly pronounced during the advanced developmental stages, particularly during the meiotic phases of gametogenesis. We identified conserved genes associated with spermatogenesis, such asdmrt1, and a novel genepsmt, that is associated with oogenesis. Additionally, putative long non-coding RNAs were upregulated in both male and female gametogenic programs. This study provides a foundational resource for germ cell research inP. dumerilii,markers for sex identification, and offers comparative data to enhance our understanding of the evolution of gametogenesis mechanisms across species.Summary statementThis study provides insights into the mechanisms of gametogenesis inPlatynereis dumeriliithrough comparative transcriptomics, unveiling sex-biased genes, including conserved and novel genes, governing this largely unexplored process.