Medaka (Oryzias latipes) Dmrt3a Is Involved in Male Fertility

Research across various species has demonstrated that the doublesex and mab-3-related transcription factor 3 (<i>dmrt3</i>) plays pivotal roles in testis development. However, the precise molecular mechanisms of <i>dmrt3</i> remain unclear. In this study, we investigated the role of <i>dmrt3</i> (<i>dmrt3a</i>) in testis development using the model organism medaka (<i>Oryzias latipes</i>). SqRT-PCR and ISH analyses revealed that <i>dmrt3a</i> is predominantly expressed in the testis, especially in the spermatid and spermatozoon. Using CRISPR/Cas9, we generated two <i>dmrt3a</i> homozygous mutants (-8 bp and -11 bp), which exhibited significantly reduced fertilization rates and embryo production. Additionally, the number of germ cells and sperm motility were markedly decreased in the <i>dmrt3a</i> mutants, manifesting as the symptoms of asthenozoospermia and oligozoospermia. Interestingly, RNA-Seq analysis showed that the deficiency of <i>dmrt3a</i> could lead to a significant downregulation of numerous genes related to gonadal development and severe disruptions in mitochondrial function. These results suggested that <i>dmrt3a</i> is essential for spermatogenesis and spermatozoa energy production. This paper provides new insights and perspectives for further exploring the molecular mechanisms underlying spermatogenesis and addressing male reproductive issues.