The ncl-1 gene and genetic mosaics of Caenorhabditis elegans.
A ncl-1 mutation results in enlarged nucleoli, which can be detected in nearly all cells of living animals by Nomarski microscopy. Spontaneous mitotic loss of a ncl-1(+)-containing free duplication in an otherwise homozygous ncl-1 mutant animal results in mosaicism for ncl-1 expression, and the patterns of mosaicism lead us to conclude that ncl-1 acts cell autonomously. The probability of mitotic loss of the duplication sDp3 is approximately constant over many cell divisions. About 60% of the losses of sDp3 at the first embryonic cell division involve nondisjunction. Frequencies of mitotic loss of different ncl-1(+)-bearing free duplications varied over a 200-fold range. The frequencies of mitotic loss were enhanced by a chromosomal him-10 mutation. We have used ncl-1 as a cell autonomous marker in the mosaic analysis of dpy-1 and lin-37. The focus of action of dpy-1 is in hypodermis. A mutation in lin-37 combined with a mutation in another gene results in a synthetic multivulva phenotype. We show that lin-37 acts cell nonautonomously and propose that it plays a role, along with the previously studied gene lin-15, in the generation of an intercellular signal by hyp7 that represses vulval development.
Hedgecock
E M
EM
Department of Biology, Johns Hopkins University, Baltimore, Maryland 21218, USA.
Herman
R K
RK
D000483:Alleles; D000818:Animals; D015415:Biomarkers; D017173:Caenorhabditis elegans / Q000166:cytology / Q000235:genetics* / Q000254:growth & development; D029742:Caenorhabditis elegans Proteins; D019070:Cell Lineage; D002466:Cell Nucleolus / Q000648:ultrastructure*; D005260:Female; D018507:Gene Expression Regulation, Developmental; D017238:Genes, Helminth; D005808:Genes, Recessive; D015801:Helminth Proteins / Q000032:analysis / Q000235:genetics* / Q000502:physiology; D008858:Microscopy, Phase-Contrast; D008938:Mitosis; D009030:Mosaicism / Q000235:genetics*; D009630:Nondisjunction, Genetic; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology; D014844:Vulva / Q000166:cytology / Q000254:growth & development
D015415:Biomarkers; D029742:Caenorhabditis elegans Proteins; D015801:Helminth Proteins; D014157:Transcription Factors; C088818:lin-15A protein, C elegans; C088819:lin-15B protein, C elegans