Figure 3.

Animals expressing only MHC with alterations in the C-terminal rod show delayed onset of movement during embryogenesis. The black bars indicate the window of time in which videotaped embryos of each genotype first twitched. The time line, measured in minutes from first cleavage, represents data from Sulston et al. (1983). Our observations of each embryo began at the 1.5-fold stage, which was designated as 420 min (see MATERIALS AND METHODS). For the top four strains, which express MHC from genomic loci, N represents the number of individuals scored. The bottom nine strains express MHC only from extrachromosomal arrays. For rescuing arrays, N represents only animals that elongated successfully, thus excluding presumptive mosaic animals that had intermediate phenotypes. In cases where inviable transgenic double mutants segregate from a heterozygous strain, N represents the number of arrested individuals that expressed the coinjection marker and/or showed delayed movement throughout the length of the body, confirming the expression of the transgene in the arrested animal.