The evolutionarily conserved genes: Tex37, Ccdc73, Prss55 and Nxt2 are dispensable for fertility in mice.

There are more than 2300 genes that are predominantly expressed in mouse testes. The role of hundreds of these genes has been studied in mouse spermatogenesis but still there are many genes whose function is unknown. Gene knockout (KO) strategy in mice is widely used for in vivo study of gene function. The present study was designed to explore the function of the four genes: Tex37, Ccdc73, Prss55 and Nxt2, which were evolutionarily conserved in eutherians. We found that these genes had a testis-enriched expression pattern in mice except Nxt2. We knocked out these genes by CRISPR/Cas9 individually and found that all the KO mice had normal fertility with no detectable difference in testis/body weight ratios, epididymal sperm counts, as well as testicular and epididymal histology from wild type mice. Although these genes are evolutionarily conserved in eutherians including human and mouse, they are not individually essential for spermatogenesis, testis development and male fertility in mice in laboratory conditions. Our report of these fertile KO data could avoid the repetition and duplication of efforts which will help in prioritizing efforts to focus on genes that are indispensable for male reproduction.