DSB-2 and SUN-1 S8P are coordinately regulated by common upstream regulator CHK-2.

Immunofluorescence images of gonads of indicated genotypes from the distal pre-meiotic region to end of pachytene, stained with DAPI and antibodies that recognize DSB-2 and SUN-1 S8P. Scale bar, 15 µm. (A) SUN-1 S8P is detected at the NE in meiotic prophase nuclei in the dsb-2 mutant germ line, indicating that although these features are coordinated during wild-type meiosis, acquisition of meiotic SUN-1 S8P does not depend on DSB-2. However, the SUN-1 S8P zone is extended in the dsb-2 mutant, indicating that the timing of its removal is affected. DSB-2 staining is absent from chromatin, indicating antibody specificity. (B) Main panel: Immunofluorescence images showing that localization of DSB-2 on chromatin and SUN-1 S8P staining at the NE are both severely reduced in the chk-2 mutant in the indicated meiotic region. Note: SUN-1 S8P signal remains present on some pre-meiotic nuclei and on late diakinesis oocytes in chk-2 mutants (data not shown; [23]). Inset: Western blot of whole-worm protein lysates from the indicated genotypes (60 worms per lane) stained with anti-DSB-2 antibodies. The arrow indicates the DSB-2 protein (32 kD), which is absent in the dsb-2 mutant but is still present in the chk-2 mutant; the asterisk indicates a non-specific band that serves as a loading control. (C) The presence of DSB-2 on chromatin and SUN-1 S8P at the NE are correlated in the him-19 mutant, in which only a small subset of nuclei are positive for these marks.