Fig. 4. Overexpression of DNA-binding domain mutations of hlh-8 causes phenotypes in the C. elegans postembryonic mesoderm. Transgenic lines were made by injecting various hlh-8 expression constructs in addition to the dominant marker, rol-6 listed in A into animals that already contained the hlh-8::gfp integrated reporter construct. Stable lines were established before the phenotype of each hlh-8 expression construct was assayed. Transgenic animals from the number of independent lines indicated were observed at either the L3 larval stage (when wild-type animals have two SMs) or the L4 stage (when wild-type animals have 16 SM descendants). We scored animals as mutant at the L3 stage if they had greater than two SMs and at the L4 stage if they had undivided SMs, underdivided SMs or greater than 16 SM descendants. Examples of phenotypes seen in L4 animals are shown in B-I. (B,C) Animals with no additional CeTwist expression. (D,E) Animals expressing wild-type CeTwist. (F-I) Animals expressing the analogous human Q119P mutation in CeTwist. (B,D,F,H) Nomarski and GFP merged images (not from identical focal planes). (C,E,G,I) GFP only images. (H,I) GFP images are merged from two different focal planes with yellow SM descendants and a green undivided SM. (B-G) Ventral views. (H,I) Lateral views with dorsal upwards. In all images anterior is towards the left. The white arrowhead indicates developing vulval opening. The white arrows indicate the position of undivided SMs. All other gfp-expressing cells that are green or yellow are SM descendants.