Fig 1: alh‐6 mutation accelerates male reproductive senescence. (a) The ability for sperm to activate upon Pronase treatment declines with age. alh‐6 mutant sperm shows premature decline compared with WT and alh‐6;prdh‐1. Statistical comparisons between strains at each age show a significant decrease in ability to activate of alh‐6 mutant spermatid compared with WT, which is restored in alh‐6;prdh‐1. (b) The ability for male sperm to compete against hermaphrodite self‐sperm also declines with age, with alh‐6 mutants showing premature decline compared to WT and alh‐6;prdh‐1 mutant males. (c, d) RT‐PCR shows unchanged expression of Prodh between young and old mice testes (c), while Aldh4a1 expression is decreased in old mice testes compared with young mice (d). (e) PRODH protein expression is consistent between young and old mice testes, but ALDH4A1 protein expression is reduced in testes of aged mice. Statistical comparisons of sperm activation and competition assay done using Fisher's exact test with p‐value adjusted for multiple comparisons between the groups. *, p < 0.05; **, p < 0.01; ***, p < 0.001; ****, p < 0.0001. All studies performed in minimum of three biological replicates; refer to Table S1 for n for each comparison