Identification of heterochronic mutants in Caenorhabditis elegans. Temporal misexpression of a collagen::green fluorescent protein fusion gene.
The heterochronic genes lin-4, lin-14, lin-28, and lin-29 specify the timing of lateral hypodermal seam cell terminal differentiation in Caenorhabditis elegans. We devised a screen to identify additional genes involved in this developmental timing mechanism based on identification of mutants that exhibit temporal misexpression from the col-19 promoter, a downstream target of the heterochronic gene pathway. We fused the col-19 promoter to the green fluorescent protein gene (gfp) and demonstrated that hypodermal expression of the fusion gene is adult-specific in wild-type animals and temporally regulated by the heterochronic gene pathway. We generated a transgenic strain in which the col-19::gfp fusion construct is not expressed because of mutation of lin-4, which prevents seam cell terminal differentiation. We have identified and characterized 26 mutations that restore col-19::gfp expression in the lin-4 mutant background. Most of the mutations also restore other aspects of the seam cell terminal differentiation program that are defective in lin-4 mutant animals. Twelve mutations are alleles of three previously identified genes known to be required for proper timing of hypodermal terminal differentiation. Among these are four new alleles of lin-42, a heterochronic gene for which a single allele had been described previously. Two mutations define a new gene, lin-58. When separated from lin-4, the lin-58 mutations cause precocious seam cell terminal differentiation and thus define a new member of the heterochronic gene pathway.
Abrahante
J E
JE
Department of Genetics and Cell Biology, University of Minnesota, St. Paul, Minnesota 55108, USA.
Miller
E A
EA
Rougvie
A E
AE
D000818:Animals; D030801:Animals, Genetically Modified; D017173:Caenorhabditis elegans / Q000166:cytology / Q000235:genetics* / Q000502:physiology; D003094:Collagen / Q000096:biosynthesis*; D003433:Crosses, Genetic; D005020:Ethyl Methanesulfonate; D005720:Gamma Rays; D015321:Gene Rearrangement; D017238:Genes, Helminth; D005816:Genetic Complementation Test; D008040:Genetic Linkage; D049452:Green Fluorescent Proteins; D007700:Kinetics; D008164:Luminescent Proteins / Q000096:biosynthesis*; D016296:Mutagenesis; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D013997:Time Factors
D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D003094:Collagen; D005020:Ethyl Methanesulfonate