Fig. 1: CifA attenuates the toxicity of CifB during spermatogenesis resulting in rescuable CI.

a Construct design of β2t-cifB and β2t-cifA. b Expression of cifB alone from either genomic insertion site (B1 or B2) impaired sperm production (indicated by the percentage of females inseminated in each cross) rendering males infertile, while expression of cifA from either genomic insertion site (A1 or A2) did not affect male fertility. Depending on the combination of genomic insertion sites, co-expression of cifA;cifB could rescue sperm production and induce sterility when crossed with wild-type (wt) females, which was rescued in crosses with wAlbB-carrying females. Lines denote median, error bars interquartile ranges, and numbers in parentheses the n. Letters indicate significant differences with an α = 0.05 calculated by a Kruskal–Wallis test: H = 261.7, P < 0.0001, d.f. = 19 followed by a two-stage linear step-up procedure of Benjamini, Krieger, and Yekutieli to correct for multiple comparisons, individual P-values are listed in the Source Data file. c The relative expression of either cifA or cifB relative to housekeeping gene rps17 in pooled adult testes (mean and s.d. are shown, n = 5 for each group). Letters indicate significant differences with an α = 0.05 calculated by a one-way ANOVA and Tukey’s post-hoc multiple pairwise comparisons test. d TUNEL staining on testes squashes from >5 day old males. DNA breaks labelled by TUNEL staining were not observed in i) wt or ii) β2t-cifA testes, whereas an abundance of DNA breaks was observed in iii) β2t-cifB and iv) wt testes treated with DNase I. DNA was labelled with DAPI stain. Scale bar, 50 µm. Source data are provided as a Source Data file.