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Fig. 2 | BMC Biology

Fig. 2

From: Lack of sex chromosome specific meiotic silencing in platypus reveals origin of MSCI in therian mammals

Fig. 2

Nucleolar activity and sex chromosome proximity in SYCP1 positive nuclei. Surface spreads of PFA fixed total testis suspensions were immunostained for SYCP1 or SYCP1 and fibrillarin prior to DNA FISH (SYCP1 slides only). a large DAPI void predicted to be the nucleolus was present in all nuclei with advanced stages of synapsis (pachynema) shown by SYCP1 staining. We identify this structure as the nucleolar like body (NLB). b DNA FISH signal positions were measured in late prophase I spermatocytes based on proximity to the NLB. An ordered hierarchy of proximity was observed with Y5 having consistent close association and the X1 end of the chain displaying more variable positions. The number of nuclei for each sex chromosome element analysed was as follows: X1q 19, X1Y1 (PAR1) 29, Y2 28, X3Y3 (PAR5) 27, Y4X5 (PAR8) 34, X5 37 and Y5 29. Graph was generated using Prism version 6. Error bars indicate mean +/− standard deviation. Right panel in C shows Y5 DNA FISH signal positioned against the NLB. c Surface spreads were immunostained for the nucleolar marker fibrillarin and SYCP1 to assess rRNA biogenesis activity at late prophase I. Fibrillarin staining is absent in late prophase I nuclei staged using SYCP1. Scale bars = 10 μm. PFA paraformaldehyde, FISH fluorescence in situ hybridisation, DAPI 4’6-diamidino-2-phenylindole

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