Fig. 1

Expression of Ck137956 and fertility of Ck137956 knockout mice. A Ck137956 mRNA expression was detected in various tissues from adult mice by RT-PCR with 18S as a loading control. NC, negative control. B qRT-PCR analysis of Ck137956 expression in postnatal mouse testes. n = 3. Data were presented as the mean ± SD. C The presence of Ck137956 mRNA was evaluated in different types of spermatogenic cells with 18S as a loading control. Spg, spermatogonia; Spc, pachytene spermatocytes; RS, round spermatids; ES, elongated spermatids. D Structure of mouse Ck137956 protein predicted by AlphaFold. E Phylogenetic tree showing the evolutionary distance of Ck137956 among different animals with branch lengths in units representing the number of amino acids substituted per site. The numbers exhibit bootstrap values. F Schematic diagram of knockout strategy by CRISPR/Cas9. Yellow and green: the single guide RNA (sgRNA) targeting sites. G Sanger sequencing showing eight bases deletion of the Ck137956 gene. H Expression of Ck137956 protein in Ck137956^+/- and Ck137956^−/− testis with Actin as a loading control. I Litter size of Ck137956^+/- and Ck137956^−/− male mice mated with wildtype female mice. n = 6. Data were presented as the mean ± SEM. ***p < 0.001. J Morphology of adult Ck137956^+/- and Ck137956^−/− testes and statistics of testis/body weight ratio. Scale bar: 3 mm. n = 6. Data were presented as the mean ± SEM. ***p < 0.001