When C. briggsae females are mated to C. nigoni males fertile F1 females are obtained. However, all of the F1 males arrest during embryogenesis. In the reciprocal cross of C. nigoni females mated to C. briggsae males, fertile F1 females and some sterile F1 male adult hybrids are obtained. The goal of this study was to determine the terminal phenotypes of the arrested embryos in these crosses. From these terminal phenotypes, tissue-specific defects in the development of hybrid embryos were inferred. Hybrid crosses were set and allowed to mated overnight. The following day gravid females were dissected to release hybrid embryos. These embryos were allowed to incubate overnight so that any viable nematodes would hatch. The arrested embryos were scored for terminal phenotypes by microscopic observation at a magnification of 1,000x. From C. briggsae mothers, 19 of 40 hybrid embryos failed to hatch. Of the 19 arrested embryos, 18 of these failed to gastrulate and 1 arrested at the comma stage. Failure to gastrulate is associated with defects in intestinal cell development while the arrested comma stage is associated with defects in actin cytoskeleton development. From C. nigoni mothers, 6 of 10 hybrid embryos failed to hatch. Of the 10 arrested embryos, 6 of these failed to gastrulate. This failure to gastrulate is once again associated with defects in intestinal cell development.
Wade, A. (2018). Terminal Phenotypes Observed in Caenorhabditis Hybrids. Wright State University, Dayton, Ohio.