Mutations in genes encoding extracellular matrix proteins suppress the emb-5 gastrulation defect in Caenorhabditis elegans |
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Authors: | K Nishiwaki and J Miwa |
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Institution: | (1) Fundamental Research Laboratories, NEC Corporation, Miyukigaoka, Tsukuba 305, Japan Tel.: +81-298-56-6106; Fax: +81-298-56-6142, JP;(2) Research & Development Group, NEC Corporation, Miyukigaoka, Tsukuba 305, Japan, JP |
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Abstract: | The second division of the gut precursor E cells is lethally accelerated during Caenorhabditis elegans gastrulation by mutations in the emb-5 gene, which encodes a presumed nuclear protein. We have isolated suppressor mutations of the temperature-sensitive allele
emb-5(hc61), screened for them among dpy and other mutations routinely used as genetic markers, and identified eight emb-5 suppressor genes. Of these eight suppressor genes, at least four encode extracellular matrix proteins, i.e., three collagens
and one proteoglycan. The suppression of the emb-5 gastrulation defect seemed to require the maternal expression of the suppressors. Phenotypically, the suppressors by themselves
slowed down early embryonic cell divisions and corrected the abnormal cell-division sequence of emb-5 mutant embryos. We propose an indirect stress-response mechanism to be the main cause of the suppression because: (1) none
of these suppressors is specific, either to particular temperature-sensitive emb-5 alleles or to the emb-5 gene; (2) suppressible alleles of genes, reported here or elsewhere, are temperature sensitive or weak; (3) the suppression
is not strong but marginal; (4) the suppression itself shows some degree of temperature dependency; and (5) none of the extracellular
matrix proteins identified here is known to be expressed in oocytes or early embryos, despite the present observation that
the suppression is maternal.
Received: 19 August 1997 / Accepted: 11 December 1997 |
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Keywords: | Caenorhabditis elegans Gastrulation mutant Suppressor mutation Extracellular matrix Cell division |
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