Fig. 1. HR6B is not required for histone ubiquitylation in spermatocytes. (A) Basic nuclear proteins were isolated from purified spermatocytes, and analyzed on western blots using anti-H2B antibody. The antibody recognizes unmodified H2B and H2B_K120ub1 (as indicated by arrows). In the control lane (Ctr), the first antibody was omitted from the incubation mixture. The boxed area is presented for each immunostaining in B. (B) Histone ubiquitylation was analyzed in spermatocytes (spc) and spermatids (spt) isolated from wild-type (+/+) and Hr6b-knockout (–/–) mice. From top to bottom, antibodies were targeting ubiquitin, H2A_K119ub1 and H2B as indicated on the right of the blots, and the modified histones are indicated by arrows. Representative results are shown; each experiment was repeated at least twice with germ cell preparations isolated from a different pool of mice. Equal amounts of protein were present in each lane, as verified by Ponceau S staining of the blot (not shown).