Suppression of him-14(it44ts) by a transgene insertion expressing GFP::COSA-1

Figure 1. Suppression of the him-14(it44ts) crossover deficit at semi-permissive temperature by the GFP::COSA-1-expressing transgene insertion meIs8. A) Example oocyte karyotypes (modified from Zalevsky et al. 1999) illustrating a normal wild-type karyotype (top) with all 6 pairs of homologous chromosomes connected by chiasmata (6 bivalents), and a karyotype from a recombination-deficient mutant (bottom) with 12 achiasmate chromosomes (12 univalents). B and C) Graphs quantifying numbers of resolvable DAPI-stained bodies in diakinesis oocyte nuclei; each diamond represents a nucleus, and mean and standard deviation are indicated. him-14(it44ts) is a temperature-sensitive mutation affecting the HIM-14/MSH-4 subunit of the MutSγ complex; meIs8 is a transgene insertion expressing a GFP::COSA-1 fusion protein. Fixation and DAPI staining were conducted as in Bessler et al. 2007, and numbers of DAPI bodies were counted in oocyte nuclei in the -1 to -3 positions. For the 20°C data, worms raised at the semi-permissive temperature of 20°C were fixed at 24 h post L4; for the 24° and 25°C data, worms were raised at 20°C until the L4 stage, then were shifted to 24° or 25°C for 24 h before fixation. (Note that this assay tends to underrepresent the actual numbers of DAPI bodies present, as some chromosomes may be too close together to be…