TY - THES AU - Gilbert, Mary Margaret PY - 1997 TI - Characterization of a pair of interacting genes, unc-112 and dim-1, that affect sarcomere development and organization KW - Thesis/Dissertation LA - eng M3 - Text AB - This dissertation focuses on two genes, unc-112 and dim-1, that affect bodywall muscle differentiation in the nematode Caenorhabditis elegans. A characterization of these two genes and their gene products will contribute to answering a fundamental question: how does a nematode make a collection of muscle proteins organize into a structure capable of movement? The roles that the unc-112 and dim-1 gene products play in the assembly, organization and contraction of sarcomeres in the various subtypes of muscle were examined using genetic, cytological, and molecular techniques. Two phenotypic classes of unc-112 alleles are known (116,123 and P. Anderson, per. comm.). The viable class allele unc-112(r367) demonstrates the importance of this gene in larval development and maintenance of sarcomeres in the gonad arms and muscle cells. The lethal class allele unc-112(st562) demonstrates that unc-112 function in embryonic muscle cells is essential (123). In order to discover the function of UNC112 protein, I cloned and sequenced several cDNAs associated with polymorphisms in two unc-112 intragenic revertant strains. The cDNA pUNC112-1 is derived from the gene ZC376.2 and identifies a tandem cluster of five highly similar genes covering 19 kb of cosmids T02B5 and ZC376. The predicted proteins of the five gene family share considerable similarity with the cholinesterase subfamily of serine proteases. Maximum parsimony analysis of this gene family with other members of the cholinesterase subfamily from C. elegans and other species indicate an ancient origin and perhaps unique function for this gene cluster. Mutations in a new gene, dim-1, have been isolated as suppressors of unc-112 paralysis. The null mutation dim-1(ra102) completely suppresses unc-112(r367) single sarcomere muscle defects and partially suppresses bodywall muscle defects. This indicates that dim-1 interaction with unc-112 is indirect. In addition, the dim-1 alleles exhibit a unique muscle phenotype of nested chevrons in some muscle cells. The distribution of mutant versus wild type muscle components have been compared and show that dense body and M-line proteins assemble and remain intact in the mutant strains but are improperly distributed across the cell membrane. A model is proposed showing how unc-112 and dim-1 may function in a signaling pathway governing sarcomere patterning in muscle cell membranes. N2 - This dissertation focuses on two genes, unc-112 and dim-1, that affect bodywall muscle differentiation in the nematode Caenorhabditis elegans. A characterization of these two genes and their gene products will contribute to answering a fundamental question: how does a nematode make a collection of muscle proteins organize into a structure capable of movement? The roles that the unc-112 and dim-1 gene products play in the assembly, organization and contraction of sarcomeres in the various subtypes of muscle were examined using genetic, cytological, and molecular techniques. Two phenotypic classes of unc-112 alleles are known (116,123 and P. Anderson, per. comm.). The viable class allele unc-112(r367) demonstrates the importance of this gene in larval development and maintenance of sarcomeres in the gonad arms and muscle cells. The lethal class allele unc-112(st562) demonstrates that unc-112 function in embryonic muscle cells is essential (123). In order to discover the function of UNC112 protein, I cloned and sequenced several cDNAs associated with polymorphisms in two unc-112 intragenic revertant strains. The cDNA pUNC112-1 is derived from the gene ZC376.2 and identifies a tandem cluster of five highly similar genes covering 19 kb of cosmids T02B5 and ZC376. The predicted proteins of the five gene family share considerable similarity with the cholinesterase subfamily of serine proteases. Maximum parsimony analysis of this gene family with other members of the cholinesterase subfamily from C. elegans and other species indicate an ancient origin and perhaps unique function for this gene cluster. Mutations in a new gene, dim-1, have been isolated as suppressors of unc-112 paralysis. The null mutation dim-1(ra102) completely suppresses unc-112(r367) single sarcomere muscle defects and partially suppresses bodywall muscle defects. This indicates that dim-1 interaction with unc-112 is indirect. In addition, the dim-1 alleles exhibit a unique muscle phenotype of nested chevrons in some muscle cells. The distribution of mutant versus wild type muscle components have been compared and show that dense body and M-line proteins assemble and remain intact in the mutant strains but are improperly distributed across the cell membrane. A model is proposed showing how unc-112 and dim-1 may function in a signaling pathway governing sarcomere patterning in muscle cell membranes. UR - https://open.library.ubc.ca/collections/831/items/1.0087795 ER - End of Reference