Fig. 1. Phenotypic analysis of mat-1 mutant and cdc-27 RNAi embryos. Micrographs show tubulin (A-D) and DAPI (A'-D') staining of individual metaphase I embryos of wild type (N2) (A,A'), mat-1(ax144) at 25°C (B,B'), mat-1(ax212) at 25.5°C (C,C') and cdc-27 RNAi (late) (D,D'). White arrows indicates oocyte chromosomes. Only wild-type embryos progress to anaphase I and exit meiosis. (E-H) Micrographs of H2B::GFP embryos within the uteri of wild type (E), cdc-27 RNAi (F,G) and mat-1(ax144) at 25°C (H). Non-viable multicellular embryos produced after 20-24 hours in cdc-27 RNAi feeding experiments [(cdc-27 RNAi (early); white arrowhead] and meiotic one-cell arrested embryos produced after 24 hours in RNAi feeding experiments [cdc-27 RNAi (late)]. (I-L) DIC micrographs of embryos in the uteri of hermaphrodites incubated at 20°C. Wild type, mat-1(ax212) [permissive; 98.3% hatch], mat-1(ax161) [semi-permissive; 16.3% hatch] and mat-1(ax520) [restrictive; 0.7% hatch]. Meiotic one-cell embryos (asterisks) accumulate at all temperature regimes for all of the mat-1 alleles (Table 1) but at permissive (J) and semi-permissive temperatures (K), the mutant embryos are able to exit meiosis and divide mitotically. At semi-permissive temperatures, the vast majority of the multicellular embryos (K) produced by mat-1 hermaphrodites die prior to morphogenesis. The average embryo is 50 µm in length.