Fig. 3.

Dominant negative effects of BRC_21–50 and BRC_60–89 on RAD-51 focus formation. BRC_21–50 blocks RAD51 focus formation, whereas BRC_60–89 results in persistent RAD-51 foci, after IR. N2(Wt) animals were microinjected with the indicated peptide (1 mg/ml), subjected to 75 Gy of γ-irradiation, and then assessed for RAD51 focus formation. (a) Representative images of fixed mitotic germ-line nuclei 2 h postinjection with 1 mg/ml peptide and a further 2 h untreated or subjected to γ-irradiation, and then immunostained with RAD-51 antibodies and counterstained with DAPI. Positive control was N2(Wt) worms microinjected with indicated peptide or injection buffer (–); negative controls were rad-51(lg08791) and brc-2(tm1086) worms. (b) Quantification of RAD-51 focus formation in a. The number of RAD-51 foci per nucleus was measured in 50 nuclei for each treatment/genotype. (c) Representative two-dimensional projections of RAD-51 foci on bivalent chromosomes in oocyte nuclei arrested at diakinesis of meiotic prophase I, 2 h postinjection with the indicated peptide and a further 5 h posttreatment with 75 Gy of γ-irradiation. (d) The percentage of −1, −2, and −3 (position in the germ line) oocyte nuclei positive for RAD-51 foci in animals of the indicated genotype subjected to the indicated treatment (as in c). Fifty nuclei were assessed for each treatment/genotype. (b and d) Error bars indicate SEM from three independent experiments.