Fig. 1.

HIM-17 regulates AIR-2 and H3pT3 localization on the short arm of the bivalents. High-magnification images of -1 oocytes at diakinesis in wild type and him-17 mutant are pictured. (A) Schematic representation of an adult C. elegans hermaphrodite gonad arm indicating nuclei in different stages of meiotic progression. The most proximal oocyte next to the spermatheca (Sp) is referred to as the -1 oocyte. (B) Costaining with anti–AIR-2 (magenta), anti–HTP-3 (green), and DAPI (blue) indicates that AIR-2 is not restricted to the short arm of the bivalents in him-17 mutants compared to wild type. Dashed boxes indicate the bivalents for which AIR-2 and HTP-3 localization are shown at higher magnification. (Middle) The chromosome configuration observed at this stage showing distinct short (S) and long (L) arms, and the localization of AIR-2 (magenta) and HTP-3 (green) for each genotype. (Right) Histogram indicates the percentage of bivalents at diakinesis with AIR-2 restricted to the short arm, mislocalized to both long and short arm, faint but in both long and short arms, or missing. A total of 102 and 97 bivalents were analyzed from the gonad arms of 18 and 112 animals for wild type and him-17, respectively, from three biological replicates. (C) Costaining with anti–LAB-1 (magenta), anti–HTP-3 (green), and DAPI (blue) indicates that a large number of bivalents in him-17 mutants exhibit LAB-1 localization restricted to the long arm as observed in wild type. (Right) Histogram indicates the percentage of bivalents at diakinesis with LAB-1 restricted to the long arm, long and short arm, faint but in both long and short arms, or missing on the chromosomes. A total of 90 and 96 bivalents from the gonad arms of 15 and 103 animals were analyzed for wild type and him-17, respectively, from three biological replicates. (D) Costaining with anti-H3pT3 (magenta), anti–HTP-3 (green), and DAPI (blue) indicates that H3pT3 signal is frequently observed on both long and short arms of the bivalents in him-17 mutants in contrast to the restricted localization only to the short arms observed in wild type. (Right) Histogram indicates the percentage of bivalents at diakinesis with H3pT3 localization restricted to the short arm, mislocalized to both long and short arms, faint but on both long and short arms, or missing on the chromosomes. A total of 99 and 72 bivalents from the gonad arms of 17 and 69 animals were analyzed for wild type and him-17, respectively, from three biological replicates. ****P < 0.0001, **P < 0.005 by the two-tailed Fisher’s exact test. (Scale bars, 2 μm.) For complete/additional statistical analysis, see Dataset S1.