Heterozygtes are WT. Hets segregate WT, UncBli and DpyLet. ct42 homozygotes are inviable at all temperatures (recessive non-conditional larval lethal). ct42 is dominant temperature sensitive maternal effect lethal. ct42 hets give more inviable progeny at 25C than at 15C. dch-1 was previously called let-354(ct42).