Normal spermatogenesis and fertility in Ddi1 (DNA damage inducible 1) mutant mice.

The ubiquitin proteins play important role in proteasomal degradation and their balanced action is essential for the crucial process of spermatogenesis. The disruption of various ubiquitinating proteins in mice revealed defective spermatogenesis, thus inferring their important function in spermatogenesis. However, the role of some testis-specific ubiquitinating proteins still needs to be discovered. This study was planned to study the in vivo function of testis-specific and evolutionarily conserved ubiquitin shuttle gene, Ddi1 (DNA damage inducible 1). Ddi1 knockout mice were generated by CRISPR/Cas9 technology and we found that Ddi1 knockout mice were fertile without obvious alterations in reproductive parameters, such as sperm number and morphology. Histological examination of testicular tissues manifested compact seminiferous tubule structure along with all type of germ cells in the knockout mice. Moreover, cytological studies of spermatocytes did not exhibit any noteworthy difference in the progression of prophase I which endorse the fact that Ddi1 has not any vital function during meiosis. Overall, these findings suggested that Ddi1 is not critical for mouse fertility under normal laboratory conditions. The outcome of this study will help researchers to avoid overlap that will not only save their resources but also concentrate their focus on indispensable genes in spermatogenesis and fertility.