Worm Breeder's Gazette 11(2): 65
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.
Mutations in the muscle-affecting gene unc-87 cause a disorganized body wall myofilament lattice (1). Electron microscopy reveals irregular groupings of abnormally arranged thick and thin filaments. Homozygous unc-87 animals are slow or paralyzed as larvae; adults move better, but not as well as wild type. As one step in understanding the role of the unc-87 gene product in muscle assembly and function, we are cloning the gene. st1005 is a spontaneous unstable allele of unc-87 isolated in a BO mut-6 background (2). All mutator-induced alleles previously identified in this background have been due to Tc1 insertions. However, attempts to detect a polymorphism associated with the unc-87 phenotype, using Tc1 as a probe, have failed (3). It is possible that insertion of Tc1 is not responsible for the mutation; other transposable elements could be tested. Another possibility is that other Tc1s in this strain made the putative polymorphism difficult to discern. Backcrossing the mutator-induced allele to decrease copy number might allow visualization of the polymorphism, but also might make it impossible to obtain coisogenic revertants of the allele. Alternatively, the physical map might be used to obtain cloned DNA from the region which would detect a polymorphism associated with the unc-87 phenotype directly in the mutator background. unc-87 is 0.05 mu to the left of dpy-14,(4) equivalent to approximately 50 kb in this region (5). Several cosmids to the left of dpy-14 were selected for hybridization to a Southern blot of BglII/SalI-digested genomic DNA prepared from the original mutant and three coisogenic revertants. Cosmid K01B11 (kindly provided by A. Coulson and J. Sulston) detected an 8.4 kb band in the mutant and a 5.9 kb band in each of the three coisogenic revertants tested. All other bands detected are identical in the mutant and the revertants. These results are consistent with an insertion of 2.5 kb in the wild type gene causing the unc-87 phenotype. BglII/SalI digestion of the cosmid also gives a 5.9 kb band. When this band is gel purified and labelled, it recognizes the polymorphism. This band is being subcloned; further characterization will include mapping the putative insertion site and obtaining a cDNA.