Fig. 5: Nuclear compaction is normal in gdrd mutant testis, but sperm bundles are potentially targeted for degradation post-coiling.

a Wild-type testis (prot:GFP/Y; +/+) and b gdrd mutant testis (prot:GFP/Y;gdrd¹/gdrd¹) labeled with phalloidin (red) to mark actin-rich individualization complexes (ICs). Prot:GFP (green) labels protaminated nuclear bundles undergoing DNA compaction. a', b' Protamination of nuclei at the basal end of gdrd mutant testis is unaffected. At the very basal end of nuclei, compact protamine-positive structures associated with coiled sperm (arrows) are present in wild-type (a') testes but are mostly absent in gdrd mutant testes (b'). In gdrd mutant testis (b'), protamine-positive remnants are present indicating that the bundled sperm may have undergone degradation. c Total number of protamine-positive nuclear bundles is unaffected in gdrd mutants indicating that nuclear compaction is unaltered in gdrd mutants. The average number of protamine-positive nuclear bundles was 24 ± 0.80 (±s.e.) and 24.9 ± 0.93 (±s.e.) in WT and gdrd day 1 testes, respectively (single replicate; n = 15; P value = 0.815). d Association between protamine-positive nuclear bundles and individualization complexes is decreased in gdrd mutant testis. The average number of protamine-positive nuclear bundles associated with actin was 17.7 ± 0.45 ( ±s.e.) and 8.5 ± 0.70 ( ±s.e.) in WT and gdrd day 1 testes, respectively (single replicate; n = 15; P value = 1.53E-6). e The number of coiled sperm bundles is decreased in gdrd mutant testis, indicating that these structures are targeted for degradation. The n value for each sample was 15. The average number of post-coiling protamine-positive structures was 17.5 ± 0.80 (±s.e.) and 7.2 ± 0.76 (±s.e.) in WT and gdrd day 1 testes, respectively (single replicate; n = 15; P value = 1.60E-6). Statistical analysis: Mann–Whitney U test (one-sided), ****P < 0.0001. Source data are provided as a Source Data file.