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 (dmrt3) plays pivotal roles in testis development. However, the precise molecular mechanisms of dmrt3 remain unclear. In this study, we investigated the role of dmrt3 (dmrt3a) in testis development using the model organism medaka (Oryzias latipes). SqRT-PCR and ISH analyses revealed that dmrt3a is predominantly expressed in the testis, especially in the spermatid and spermatozoon. Using CRISPR/Cas9, we generated two dmrt3a 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 dmrt3a mutants, manifesting as the symptoms of asthenozoospermia and oligozoospermia. Interestingly, RNA-Seq analysis showed that the deficiency of dmrt3a could lead to a significant downregulation of numerous genes related to gonadal development and severe disruptions in mitochondrial function. These results suggested that dmrt3a 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.