Fig. 5

Late prophase I spermatocytes have reduced transcription and increased H3K9me2. Surface spreads of PFA fixed platypus total testis suspensions were hybridised with a Cot-1 RNA FISH probe and counterstained with DAPI or immunostained for H3K9me2 and SMC3. a Nuclei with a characteristic DAPI appearance with large DAPI void (arrowheads) have a marked reduction in Cot-1 RNA FISH signal while other cell types are positive for Cot-1 hybridisation signal. Scale bar = 20 μm. b Note two to three intense Cot-1 foci are consistently present in late prophase I nuclei. Scale bar = 10 μm. c H3K9me2 staining was low in zygotene and diplotene but increased through pachytene with reductions in late pachytene (H3K9me2 panel). Z = zygotene, VEP = very early pachytene, EP = early pachytene, LP = late pachytene and D = diplotene. Scale bar = 10 μm. PFA paraformaldehyde, FISH fluorescence in situ hybridisation, DAPI 4’6-diamidino-2-phenylindole