Tdrd15 is dispensable for male fertility and spermatogenesis in the golden hamster.

Tudor domain-containing proteins (TDRDs) constitute an evolutionarily conserved protein family and are critical for germline development and piRNA pathway regulation, with established roles in male fertility. While multiple TDRD family members have been functionally linked to spermatogenic impairment, the precise biological role of TDRD15 remains to be elucidated. We used CRISPR/Cas9-mediated gene editing to generate Tdrd15 knockout (KO) golden hamsters (Mesocricetus auratus), a model necessitated by the absence of a functional Tdrd15 ortholog in the mouse genome, to investigate its function in male reproduction. Phylogenetic analysis demonstrated that TDRD15 is strongly conserved among eutherian mammals, with testis-restricted expression patterns in hamsters. Despite the successful induction of frameshift mutations and significant transcriptional knockdown, Tdrd15 KO males maintained normal fertility parameters, including unaltered testicular architecture, spermatogenic progression (confirmed by periodic acidic-Schiff (PAS) staining and immunohistochemistry), and sperm quality metrics determined using a computer-assisted analysis. Quantitative polymerase chain reaction (qPCR) revealed compensatory overexpression of paralogous Tdrd genes in KO testes, implying functional redundancy within this protein family. This study provides the first experimental evidence that TDRD15 is dispensable for male fertility in golden hamsters under physiological conditions, thereby challenging the prevailing assumptions of its obligatory function in spermiogenesis. Altogether, these findings support a more targeted allocation of research efforts within the field of male reproductive biology.