Worm Breeder's Gazette 9(1): 51
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
We isolated and partially characterized a recessive cuticle mutation, sc109, that suppresses formation of blisters. While animals homozygous for sc109 have marked cuticle protein differences when compared to N2, mutants cannot be readily distinguished from wild-type when viewed with a dissecting microscope. The most straight-forward interpretation of our results is that the sc109 locus affects post- translational processing of cuticle proteins (as is probably also the case for at least some bli mutations). Other explanations cannot yet be ruled out however. The sc109 mutation was obtained in a strain carrying a bli-1 allele by selecting F2 wild-type revertants following EMS mutagenesis of bli-( sc73)II hermaphrodites. The sc109 locus is on LGV, but has not been mapped further. While sc109 hermaphrodites appear wild-type, males sometimes have small tail blisters which are a slight impediment to sinusoidal movement, but do not prevent mating. In addition to suppressing blister formation in bli-1(sc73) animals, sc109 suppresses blisters in bli-2(e768), 7) and bli-6(sc16) mutants. Alleles of bli-3 and bli-5 were not examined. Suppression is not always complete in hermaphrodites, as small blips can be found on occasional animals. In males, suppression is almost never complete and above their bursa small blisters appear that enlarge somewhat with age. However, newly molted males are fertile and mate well. Suppression may be specific for bli mutations since several dpy and col mutations were not affected by sc109; however, this question was not addressed systematically. Cuticles of sc109bli-1(sc73) double mutants differ from those of both the bli-1 parent and N2 when examined by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). In TEM s of bli-1 cuticles, a large space, presumably corresponding to the blister in live animals and containing much electron dense material is apparent between the cortical and basal layers. This space is gone in the sc109 containing revertant. In addition, the cuticle of the revertant is one-third to one-half as thick as that of N2 animals. We have not seen struts in revertant cuticles either by TEM or by phase contrast microscopy, examination by SEM revealed ill-formed alae appearing as three rows of small bumps running head to tail with various-sized spaces between the bumps of a single row. Cuticle proteins isolated from sc109 animals were separated by SDS- PAGE and stained. Animals carrying sc109, in the presence or absence of bli-1(sc73), had 25-33% as much soluble cuticle protein per animal as N2. While electrophoretic profiles of wild-type and bli-1 cuticle proteins were identical, sc109 cuticles had much less of a major protein band, cpD (MW~100,000) and no apparent cpF (MW~200,000) a minor band. Less pronounced quantitative differences were apparent for other cuticle proteins. When sc109 cuticle proteins were separated by 2D gel electrophoresis (IEF followed by SDS-PAGE) and visualized by Western blotting, we found identical spots with mutant and wild-type cuticle proteins, but quantitative differences were marked.