A mutant affecting the heavy chain of myosin in Caenorhabditis elegans

Epstein, Henry F.; Waterston, Robert H.; Brenner, Sydney

doi:10.1016/0022-2836(74)90374-x

Cited by 211 publications

(89 citation statements)

References 26 publications

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“…Second, ultrastructural and protein analyses of the homozygous-viable mutants in dicate that each of the mutations reduces MHC accu mulation and affects the accumulation and morphology of muscle thick filaments. The ultrastructural phenotypes are consistent with those of hypomorphic MHC mutants described previously in Caenorhabditis elegans (Epstein et al 1974;Waterston et al 1980) andD. melanogaster (O'Donnell andBernstein 1988).…”

Section: Genes and Developmentsupporting

confidence: 88%

“…This phenotype is consistent with that seen in the muscles of Mhc^l + heterozygotes (O'Donnell and Bemstein 1988), where a reduced number of thick filaments and abnormally large-diam eter thick filaments exist. This phenotype is also similar to that found in the body wall muscle of hypomorphic MHC mutants in C. elegans (Epstein et al 1974;Waterston et al 1980). In this muscle, two genes [MHC A and MHC B (or the unc-54 locus)], produce individual MHC isoforms that, together, assemble to form thick fila ments (Garcea et al 1978;Miller et al 1983).…”

Section: Mhc Isofoim Diversity and Differential Localizationsupporting

confidence: 80%

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Ultrastructural and molecular analyses of homozygous-viable Drosophila melanogaster muscle mutants indicate there is a complex pattern of myosin heavy-chain isoform distribution.

O'Donnell¹,

Collier²,

Mogami³

et al. 1989

Genes Dev.

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We describe the ultrastructural and initial molecular characterization of four homozygous-viable, dominantflightless mutants of Drosophila melanogaster. Genetic mapping indicates that these mutations are inseparable from the known muscle myosin heavy-chain (MHC) allele Mhc^, and each mutation results in a muscle-specific reduction in MHC protein accumulation. The indirect flight muscles (IFMs) of each of these homozygous mutants fail to accumulate MHC, lack thick filaments, and do not display normal cylindrical myofibrils. As opposed to the null phenotype observed in the IFM, normal amounts of MHC accumulate in the leg muscles of three of these mutants, whereas the fourth mutant shows a 45% reduction in leg muscle MHC. The ultrastructure of the tergal depressor of the trochanter muscle (TDT, or jump muscle] is normal in one mutant, completely lacks thick filaments in a second mutant, and displays a reduction of thick filaments in two mutants. The thick filament reduction in this latter class of mutants is limited to the four smaller anterior cells of the TDT, indicating that the TDT is a mixed fiber-type muscle. Because all isoforms of muscle MHC are encoded by alternative splicing of transcripts from a single gene, our results suggest that there is a complex pattern of MHC isoform accumulation in Drosophila, The phenotypes of the homozygous-viable mutants provide evidence for the differential localization of MHC isoforms in different muscles, within the same muscle, and even within a single muscle cell. The mutant characteristics also suggest that the use of some alternative exons is shared among the IFM, TDT, and additional muscles whereas the use of others is unique to the IFM.[Key Words: Drosophila-, muscle mutants; myosin heavy chain; alternative RNA splicing]

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Section: Genes and Developmentsupporting

confidence: 88%

Section: Mhc Isofoim Diversity and Differential Localizationsupporting

confidence: 80%

Ultrastructural and molecular analyses of homozygous-viable Drosophila melanogaster muscle mutants indicate there is a complex pattern of myosin heavy-chain isoform distribution.

O'Donnell¹,

Collier²,

Mogami³

et al. 1989

Genes Dev.

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“…Thus, antisense RNA against the glh genes can reduce the level of multiple P-granule components below detectability and prevent normal germ-line development. As a control, worms were injected with a 1.0-kb antisense RNA to the unc-54 gene, which encodes myosin heavy chain (47,48). The injected worms produced some uncoordinated but all fertile offspring (31 Unc and no sterile worms out of 371 total progeny) whose germ lines stained positively for GLH protein (data not shown).…”

Section: Resultsmentioning

confidence: 94%

Multiple potential germ-line helicases are components of the germ-line-specific P granules of Caenorhabditis elegans

Gruidl

Smith

Kuznicki

et al. 1996

Proc. Natl. Acad. Sci. U.S.A.

234

211

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Two components of the germ-line-specific P granules of the nematode Caenorhabditis elegans have been identified using polyclonal antibodies specific for each. Both components are putative germ-line RNA helicases (GLHs) that contain CCHC zinc fingers of the type found in the RNA-binding nucleocapsid proteins of retroviruses. The predicted GLH-1 protein has four CCHC fingers; GLH-2 has six. Both GLH proteins localize in the P granules at all stages of germ-line development. However, the two glh genes display different patterns of RNA and protein accumulation in the germ lines of hermaphrodites and males. Injection of antisense glh-1 or glh-2 RNA into wild-type worms causes some offspring to develop into sterile adults, suggesting that either or both genes are required for normal germ-line development. As these very similar glh genes physically map within several hundred kilobases of one another, it seems likely that they represent a fairly recent gene duplication event.Embryos of the free-living soil nematode Caenorhabditis elegans generate distinct founder cells via a series of asymmetric cell divisions. At each division, the germ-line daughter cell inherits distinctive non-membrane-bound particles, called P granules (1-3). P granules are partitioned to the primordial germ cell P 4 of the 16-to 24-cell embryo and become perinuclear. P granules persist around the nuclei of all germ cells, until gametogenesis, at which point they are excluded from mature sperm and become dispersed within the cytoplasm of mature oocytes in preparation for cytoplasmic localization in the embryo. Although the distribution pattern of nematode P granules has been well-studied, the identity and function of P-granule components have yet to be determined.Germ granules are found in many species (4, 5). The germ-line-specific polar granules of Drosophila melanogaster have been well-studied, with a number of different genes identified that are required for polar granule assembly and germ-cell formation, including vasa, staufen, valois, oskar, tudor, mago nashi, and germ-cell-less (6-15). With the exception of vasa, these genes encode novel proteins. Vasa, however, is a member of a family of proteins with recognizable motifs and predictable function. Vasa is an RNA helicase of the DEAD-box family (8, 9) whose ATP-dependent RNA helicase activity has been demonstrated in vitro (16). As polar granules contain RNA as well as protein (11,12,15,17), a germ-linespecific RNA helicase may function to bind and unwind RNAs necessary for germ-line development. Several potential vasa homologues have been cloned, including glh-1 (germ-line helicase 1) from Caenorhabditis, Xvh (Xenopus vasa homologue), mvh (mouse vasa homologue), and rvh (rat vasa homologue) (18)(19)(20)(21). glh-1 in C. elegans is unique among RNA helicase genes reported, including vasa, in that its predicted product contains four retroviral-like zinc fingers (18). We have identified a second C. elegans germ-line RNA helicase gene, glh-2, that also encodes zinc fingers. Immunolocali...

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“…Epstein et al (10) have recently described a mutant nematode which exhibits a shortened myosin peptide, apparently as a result of a structural gene mutation in the gene for myosin. They have interpreted their result in terms of peptide chain termination.…”

Section: Methodsmentioning

confidence: 99%

Possible peptide chain termination mutants in thymide kinase gene of a mammalian virus, herpes simplex virus.

Summers¹,

Wagner²,

Summers³

1975

Proc. Natl. Acad. Sci. U.S.A.

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Mutations in the viral gene coding for the thymidine kinase (ATP:thymidine 5'-phosphotransferase, EC 2.7.1.75) induced by herpes simplex virus have been obtained by selection of virus resistant to bromoodeoxyuridine when grown in thymidine-kinase-deficient LMTK-mouse cells. Proteins labeled after infection of Vero (monkey) cells with herpes simplex virus were analyzed by gel electrophoresis and one protein of about 40,000 daltons was consistently altered in a number of thymidine-kinase-deficient mutants. Many viral mutants lacked this peptide and one class of these mutants induced the synthesis of new shorter peptides. Revertant virus could be selected which simultaneously regained the ability to induce thymidine kinase activity, regained the intact thymidine kinase peptide, and lost the ability to synthesize the shorter peptide fragment. These mutants comprise a class of animal virus mutants which have the properties expected of peptide chain termination mutants.The use of mutants which are sensitive to translational suppression has greatly advanced the study of bacteria and bacterial viruses (1). With the exception of fungi (2, 3), such mutations have not been demonstrated in eukaryotic systems. Two approaches to obtain such mutants are immediately apparent. First is to obtain a cell which has a suppressor gene and then to select mutants which are suppressible. Second, one can obtain potentially suppressible mutations and then use these to search for suppressor mutations. It is this latter course which we have taken, and we report here on the first part of the problem, namely the isolation and characterization of mutants which have the properties expected of peptide chain termination, potentially suppressible mutations.We have studied mutants in the thymidine kinase (ATP: thymidine 5'-phosphotransferase, EC 2.7.1.75) (TK) gene of herpes simplex virus (HSV). This system was chosen for several reasons. The enzyme thymidine kinase is not a required viral function, so defective mutants can be grown even in the absence of suppressor activity. TK-deficient mutants can be selected on the basis of their resistance to the lethal effects of 5-bromo-deoxyuridine (BrdUrd) (4). In addition, a sensitive and simple enzyme assay is available (5). The recent identification of the TK polypeptide by gel electrophoresis of immunoprecipitated, labeled infected cell proteins was also highly encouraging (6). The results of our studies show that a single viral-induced polypeptide is affected by mutation to BrdUrd resistance with simultaneous loss of TK activity, that revertants to BrdUrd sensitivity regain the affected polypeptide and TK activity, and that, in some cases, a shorter peptide is observed which appears in the mutants and is absent in the revertants. The simplest interpretation of these results is in terms of classical peptide chain termination mutants. Selection of Revertants. In order to select revertants of HSV-TK which had regained the ability to induce TK, certain of the virus mutants were grown in LMTK-cells...

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A mutant affecting the heavy chain of myosin in Caenorhabditis elegans

Cited by 211 publications

References 26 publications

Ultrastructural and molecular analyses of homozygous-viable Drosophila melanogaster muscle mutants indicate there is a complex pattern of myosin heavy-chain isoform distribution.

Ultrastructural and molecular analyses of homozygous-viable Drosophila melanogaster muscle mutants indicate there is a complex pattern of myosin heavy-chain isoform distribution.

Multiple potential germ-line helicases are components of the germ-line-specific P granules of Caenorhabditis elegans

Possible peptide chain termination mutants in thymide kinase gene of a mammalian virus, herpes simplex virus.

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