Tex19.1 promotes Spo11-dependent meiotic recombination in mouse spermatocytes
Fig 6
Ubr2-/- Spermatocytes Phenocopy the Retrotransposon Derepression and Asynapsis Phenotypes Present in Tex19.1-/- Mutants. (A) In situ hybridisation for MMERVK10C retrotransposon RNA in Ubr2-/- testes. Specific signal (dark purple precipitate) is present in Ubr2-/- spermatocytes hybridised with an antisense MMERVK10C probe. Scale bar 100 μm. (B) qRT-PCR for MMERVK10C, IAP and LINE-1 retrotransposons in P16 Ubr2-/- testes. Mean abundance of retrotransposon RNAs relative to β-actin is shown for two Ubr2+/+ and three Ubr2-/- animals. ns indicates no significant difference, * indicates p<0.05 (Student's t-test). (C) Chromosome spreads from testes from three Ubr2+/+ and three Ubr2-/- animals were immunostained with antibodies to SYCP3 and SYCP1, and SYCP3-positive nuclei scored for meiotic substage (n = 398, 595). Ubr2-/- spreads contained a significant proportion of aberrant pachyene nuclei containing asynapsed chromosomes, but few diplotene or metaphase I nuclei compared to Ubr2+/+ controls. (D) Immunostaining of chromosome spreads from Ubr2+/+ and Ubr2-/- spermatocytes for SYCP3 (red) and SYCP1 (green). Asynapsed chromosomes assemble SYCP3 but not SYCP1, and examples involving non-homologous interactions (NH), incomplete synapsis between homologs (IS), and isolated chromosomes (IC) are labelled. Scale bar 10 μm. (E) Percentage of asynapsed pachytene Ubr2+/+ and Ubr2-/- spermatocytes exhibiting the indicated categories of asynapsed chromosomes (n = 17, 99 respectively from a total of three Ubr2+/+ and three Ubr2-/- mice). Each nucleus is typically represented in more than one category. Fully autosomally synapsed pachytene nuclei are not included in this analysis, and only asynapsed pachytene nuclei containing clearly distinguishable asynapsed chromosome configurations were scored.