Lethal mutations defining 112 complementation groups in a 4.5 Mb sequenced region of Caenorhabditis elegans chromosome III

Abstract The organization of essential genes in the unc-22 region, defined by the deficiency sDf2 on linkage group IV, has been studied. Using the balancer nT1 (IV;V), which suppresses recombination over 49 map units, 294 lethal mutations on LGIV(right) and LGV(left) were recovered using EMS mutagenesis. Twenty-six of these mutations fell into the unc-22 region. Together with previously isolated lethal mutations, there is now a total of 63 lethal mutations which fall into 31 complementation groups. Mutations were positioned on the map using eight overlapping deficiencies in addition to sDf2. The lethal alleles and deficiencies in the unc-22 region were characterized with respect to their terminal phenotypes. Mapping of these lethal mutations shows that sDf2 deletes a minimum of 1.8 map units and a maximum of 2.5 map units. A minimum estimate of essential gene number for the region using a truncated Poisson calculation is 48. The data indicate a minimum estimate of approximately 3500 essential genes in the Caenorhabditis elegans genome.

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Essential genes in the hDf6 region of chromosome I in Caenorhabditis elegans.

Genetics ◽

10.1093/genetics/126.3.583 ◽

1990 ◽

Vol 126 (3) ◽

pp. 583-592

Author(s):

A M Howell ◽

A M Rose

Keyword(s):

Caenorhabditis Elegans ◽

Mutation Rate ◽

Lower Proportion ◽

Essential Genes ◽

Ethyl Methanesulfonate ◽

Lethal Mutations ◽

Large Numbers ◽

Complementation Groups ◽

Minimum Estimate ◽

Chromosome I

Abstract In this paper we describe the analysis of essential genes in the hDf6 region of chromosome I of Caenorhabditis elegans. Nineteen complementation groups have been identified which are required for the growth, survival or fertility of the organism (essential genes). Since ten of these genes were represented by more than one allele, a Poisson calculation predicts a minimum estimate of 25 essential genes in hDf6. The most mutable gene in this region was let-354 with seventeen alleles. An average mutation rate of 5 x 10(-5) mutations/gene/chromosome screened was calculated for an ethyl methanesulfonate dose of 15 mM. Mutations were recovered by screening for lethal mutations using the duplication sDp2 for recovery. Our analysis shows that duplications are very effective for maintenance and mapping of large numbers of lethal mutations. Approximately 600 lethal mutations were mapped in order to identify the 54 that are in the deficiency hDf6. The hDf6 region appears to have a lower proportion of early arresting mutations than other comparably sized regions of the genome.

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Genomic organization in Caenorhabditis elegans: deficiency mapping on linkage group V(left)

Genetics Research ◽

10.1017/s0016672300027476 ◽

1988 ◽

Vol 52 (2) ◽

pp. 105-118 ◽

Cited By ~ 17

Author(s):

Raja E. Rosenbluth ◽

Teresa M. Rogalski ◽

Robert C. Johnsen ◽

Linda M. Addison ◽

David L. Baillie

Keyword(s):

Caenorhabditis Elegans ◽

Linkage Group ◽

Mutant Allele ◽

Genomic Organization ◽

Group V ◽

Recessive Lethal ◽

C Elegans ◽

Lethal Mutations ◽

Autosomal Region ◽

Complementation Groups

SummaryIn this study we genetically analyse a large autosomal region (23 map units) in Caenorhabditis elegans. The region comprises the left half of linkage group V [LGV(left)] and is recombinationally balanced by the translocation eT1(III; V). We have used rearrangement breakpoints to subdivide the region from the left end of LGV to daf-11 into a set of 23 major zones. Twenty of these zones are balanced by eT1. To establish the zones we examined a total of 110 recessive lethal mutations derived from a variety of screening protocols. The mutations identified 12 deficiencies, 1 duplication, as well as 98 mutations that fell into 59 complementation groups, significantly increasing the number of available genetic sites on LGV. Twenty-six of the latter had more than 1 mutant allele. Significant differences were observed among the alleles of only 6 genes, 3 of which have at least one ‘visible’ allele. Several deficiencies and 3 alleles of let-336 were demonstrated to affect recombination. The duplication identified in this study is sDp30(V;X). Lethal mutations covered by sDp30 were not suppressed uniformly in hermaphrodites. The basis for this non-uniformity may be related to the mechanism of X chromosome dosage compensation in C. elegans.

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Genetic analysis of a large autosomal region in Caenorhabditis elegans by the use of a free duplication

Genetics Research ◽

10.1017/s0016672300027099 ◽

1987 ◽

Vol 49 (3) ◽

pp. 207-213 ◽

Cited By ~ 16

Author(s):

A. M. Howell ◽

S. G. Gilmour ◽

R. A. Mancebo ◽

A. M. Rose

Keyword(s):

Caenorhabditis Elegans ◽

Gamma Radiation ◽

Essential Gene ◽

Single Gene ◽

Gene Mutations ◽

Essential Genes ◽

Induced Mutations ◽

Lethal Mutations ◽

Autosomal Region ◽

Complementation Groups

SummaryIn this paper we describe the use of a free duplication, sDp2 (I;f), for the recovery, maintenance, and analysis of mutations defining essential genes in the left third of Linkage Group I of Caenorhabditis elegans. The lethals were induced in a strain of genotype (sDp2) + /dpy-5 + unc-13/ dpy-5 unc-15 +, using either 12 mM ethylmethane sulphonate or 1500 r of gamma radiation. Lethal mutations linked to the dpy-5 unc-13 chromosome were recognized by the absence of Dpy-5 Unc-13 individuals amongst the self progeny and were maintained by isolating Unc-13 hermaphrodites. These strains – which have two mutant alleles of the essential gene and a wild-type allele on the duplication – are balanced, since crossing-over does not occur between sDp2 and the normal homologues. Using this sytem we have recovered 58 EMS-induced mutations. These have been characterized with regard to map position and complementation. Twenty-nine of the EMS-induced mutations lie to the left of dpy-5 and define 20 complementation groups; 3 were inseparable from dpy-5 and define 3 complementation groups; 21 were to the right and define 17 complementation groups. Among a set of 29 gamma radiation-induced lethal mutations, 17 appear to be single gene mutations or are very small deletions. We estimate that we have identified from one-sixth to one-half of the essential genes in the sDp2 region.

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Maternal-effect lethal mutations on linkage group II of Caenorhabditis elegans.

Genetics ◽

10.1093/genetics/120.4.977 ◽

1988 ◽

Vol 120 (4) ◽

pp. 977-986

Author(s):

K J Kemphues ◽

M Kusch ◽

N Wolf

Keyword(s):

Caenorhabditis Elegans ◽

Linkage Group ◽

Maternal Effect ◽

Essential Genes ◽

The Other ◽

C Elegans ◽

Lethal Mutations ◽

Embryonic Lethal ◽

Embryonic Lethal Mutations ◽

F1 Progeny

Abstract We have analyzed a set of linkage group (LG) II maternal-effect lethal mutations in Caenorhabditis elegans isolated by a new screening procedure. Screens of 12,455 F1 progeny from mutagenized adults resulted in the recovery of 54 maternal-effect lethal mutations identifying 29 genes. Of the 54 mutations, 39 are strict maternal-effect mutations defining 17 genes. These 17 genes fall into two classes distinguished by frequency of mutation to strict maternal-effect lethality. The smaller class, comprised of four genes, mutated to strict maternal-effect lethality at a frequency close to 5 X 10(-4), a rate typical of essential genes in C. elegans. Two of these genes are expressed during oogenesis and required exclusively for embryogenesis (pure maternal genes), one appears to be required specifically for meiosis, and the fourth has a more complex pattern of expression. The other 13 genes were represented by only one or two strict maternal alleles each. Two of these are identical genes previously identified by nonmaternal embryonic lethal mutations. We interpret our results to mean that although many C. elegans genes can mutate to strict maternal-effect lethality, most genes mutate to that phenotype rarely. Pure maternal genes, however, are among a smaller class of genes that mutate to maternal-effect lethality at typical rates. If our interpretation is correct, we are near saturation for pure maternal genes in the region of LG II balanced by mnC1. We conclude that the number of pure maternal genes in C. elegans is small, being probably not much higher than 12.

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MUTATIONAL ANALYSIS OF THE REGION SURROUNDING THE 93D HEAT SHOCK LOCUS OF DROSOPHILA MELANOGASTER

Genetics ◽

10.1093/genetics/106.2.249 ◽

1984 ◽

Vol 106 (2) ◽

pp. 249-265

Author(s):

Jym Mohler ◽

Mary Lou Pardue

Keyword(s):

Drosophila Melanogaster ◽

Heat Shock ◽

Mutational Analysis ◽

Point Mutations ◽

Γ Irradiation ◽

Lethal Mutations ◽

Complementation Groups ◽

In Trans ◽

Shock Locus ◽

Shock Proteins

ABSTRACT The region containing subdivisions 93C, 93D and 93E on chromosome 3 of Drosophila melanogaster has been screened for visible and lethal mutations. Treatment with three mutagens, γ irradiation, ethyl methanesulfonate and diepoxybutane, has produced mutations that fall into 20 complementation groups, including the previously identified ebony locus. No point mutations affecting the heat shock locus in 93D were detected; however, a pair of deficiencies that overlap in the region of this locus was isolated. Flies heterozygous in trans for this pair of deficiencies are capable of producing all of the major heat shock puffs (except 93D) and the major heat shock proteins. In addition, these flies show recovery of normal protein synthesis following a heat shock.

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Fine-structure genetics of ama-1, an essential gene encoding the amanitin-binding subunit of RNA polymerase II in Caenorhabditis elegans.

Genetics ◽

10.1093/genetics/120.2.423 ◽

1988 ◽

Vol 120 (2) ◽

pp. 423-434

Author(s):

A M Bullerjahn ◽

D L Riddle

Keyword(s):

Fine Structure ◽

Caenorhabditis Elegans ◽

Rna Polymerase ◽

Rna Polymerase Ii ◽

Essential Gene ◽

Resistance Mutation ◽

Lethal Mutation ◽

Intragenic Recombination ◽

Lethal Mutations ◽

Binding Subunit

Abstract A fine-structure genetic map has been constructed for ama-1 IV, an essential gene in Caenorhabditis elegans encoding the amanitin-binding subunit of RNA polymerase II. Sixteen EMS-induced recessive-lethal mutations have been positioned in the gene by determining their intragenic recombination frequencies with m118, a mutation that confers dominant resistance to alpha-amanitin. The 16 mutants, all isolated in the ama-1(m118) background, include 13 that are early larval lethals, and three that are mid-larval lethals, at 25 degrees. Six of the mutants exhibit temperature-dependence in the severity of their phenotype. Intragenic recombination between the lethal site and the parental resistance mutation was detected by means of resistance to amanitin. Recombinants were detected at frequencies as low as 2 X 10(-6). The segregation of the closely linked flanking markers, unc-17 and unc-5, revealed whether the lethal mutation was to the left or the right of m118. By adding the distances between the extreme left and right mutations, the ama-1 gene is estimated to be 0.011 map unit long, with m118 positioned 0.004 map unit from the left-most lethal mutation. To order the lethal mutations with respect to each other, viable heteroallelic strains were constructed using the free duplication, mDp1[unc-17(e113) dpy-13(+) ama-1(+)]. The heteroallelic strains were sensitive to amanitin, and recombination events between the lethal mutations were specifically selected by means of the dominant amanitin resistance encoded on the recombinant chromosome. The segregation of outside markers revealed the left-right order of the lethal mutations. The position of mutations within the gene is nonrandom. Functional domains of the ama-1 gene indicated by the various lethal phenotypes are discussed.

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Analysis of lethal mutations induced in a mutator strain that activates transposable elements in Caenorhabditis elegans

Genome ◽

10.1139/g90-017 ◽

1990 ◽

Vol 33 (1) ◽

pp. 109-114 ◽

Cited By ~ 7

Author(s):

Denise V. Clark ◽

Robert C. Johnsen ◽

Kim S. McKim ◽

David L. Baillie

Keyword(s):

Caenorhabditis Elegans ◽

Linkage Group ◽

Gamma Ray ◽

Hot Spot ◽

Single Gene ◽

Gene Mutations ◽

Group Iv ◽

Group V ◽

Mutator Strain ◽

Lethal Mutations

A screen was conducted for lethal mutations in the nematode Caenorhabditis elegans in a strain containing the mutator mut-4(st700)I to examine the nature of mutator-induced lethal mutations within two large chromosomal regions comprising a total of 49 map units (linkage group IV (right) and linkage group V (left)). The genetic analysis of 28 lethal mutations has revealed that the mutator locus mut-4(st700)I causes both putative single-gene mutations and deficiencies. We have identified lethal mutations in three different genes, in addition to seven deficiencies. There is a mutational hot spot on linkage group V (left) around the lin-40 locus. Six mutations appear to be alleles of lin-40. In addition, 5 of 7 deficiencies have breakpoints at or very near lin-40. All seven deficiencies delete the left-most known gene on linkage group V (left) and thus appear to delete the tip of the chromosome. This is in contrast to gamma ray and formaldehyde induced deficiencies, which infrequently delete the closest known gene to the tip of a chromosome.Key words: Caenorhabditis elegans, mutator, deficiencies, lethal mutations.

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Isolation and genetic analysis of Saccharomyces cerevisiae mutants supersensitive to G1 arrest by a factor and alpha factor pheromones.

Molecular and Cellular Biology ◽

10.1128/mcb.2.1.11 ◽

1982 ◽

Vol 2 (1) ◽

pp. 11-20 ◽

Cited By ~ 208

Author(s):

R K Chan ◽

C A Otte

Keyword(s):

Saccharomyces Cerevisiae ◽

Mating Type ◽

Solid Medium ◽

G1 Arrest ◽

Alpha Cells ◽

Opposite Mating Type ◽

Alpha Factor ◽

Complementation Groups ◽

Chromosome Iii ◽

The Right

Eight independently isolated mutants which are supersensitive (Sst-) to the G1 arrest induced by the tridecapeptide pheromone alpha factor were identified by screening mutagenized Saccharomyces cerevisiae MATa cells on solid medium for increased growth inhibition by alpha factor. These mutants carried lesions in two complementation groups, sst1 and sst2. Mutations at the sst1 locus were mating type specific: MATa sst1 cells were supersensitive to alpha factor, but MAT alpha sst1 cells were not supersensitive to a factor. In contrast, mutations at the sst2 locus conferred supersensitivity to the pheromones of the opposite mating type on both MATa and MAT alpha cells. Even in the absence of added alpha pheromone, about 10% of the cells in exponentially growing cultures of MATa strains carrying any of three different alleles of sst2 (including the ochre mutation sst2-4) had the aberrant morphology ("shmoo" shape) that normally develops only after MATa cells are exposed to alpha factor. This "self-shmooing" phenotype was genetically linked to the sst2 mutations, although the leakiest allele isolated (sst2-3) did not display this characteristic. Normal MATa/MAT alpha diploids do not respond to pheromones; diploids homozygous for an sst2 mutation (MATa/MAT alpha sst2-1/sst2-1) were still insensitive to alpha factor. The sst1 gene was mapped to within 6.9 centimorgans of his6 on chromosome IX. The sst2 gene was unlinked to sst1, was not centromere linked, and was shown to be neither linked to nor centromere distal to MAT on the right arm of chromosome III.

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Genetic and molecular analysis of new female-specific lethal mutations at the gene Sxl of Drosophila melanogaster.

Genetics ◽

10.1093/genetics/129.2.371 ◽

1991 ◽

Vol 129 (2) ◽

pp. 371-383 ◽

Cited By ~ 1

Author(s):

B Granadino ◽

M Torres ◽

D Bachiller ◽

E Torroja ◽

J L Barbero ◽

...

Keyword(s):

Drosophila Melanogaster ◽

Point Mutation ◽

Dosage Compensation ◽

The Other ◽

Initial Activity ◽

Lethal Mutations ◽

Dna Insertion ◽

Complementation Groups ◽

Activity State ◽

Female Specific

Abstract We have isolated three female-specific lethal mutations at the gene Sex-lethal (Sxl): Sxlfb, Sxlfc and Sxlfd. We have carried out the complementation analysis between these mutations and other previously reported Sxlf mutations. It is possible to classify the alleles tested in this report into two complementation groups: the bc group defined by Sxlfb, and Sxlfc, and the LS group defined by SxlfLS. The other alleles tested affect both complementation groups albeit with different degrees. Contrary to what happens with mutations at the LS group, mutations at the bc group do not affect sex determination, nor late dosage compensation nor oogenesis. Both Sxlfb and Sxlfc present a DNA insertion of at least 5 kb between position -10 and -11 on the molecular map, within the fourth intron. On the contrary, Sxlfd, a strong mutation affecting all Sxl functions, is not associated to any detectable DNA alteration in Southern blots, so that it seems to be a "point" mutation. In agreement with their phenotypes, both Sxlfc/SxlfLS and Sxlfc homozygous female larvae express only the late Sxl transcripts characteristic of females, while females homozygous for SxlfLS express only the late Sxl transcripts characteristic of males. Moreover, Sxlfc presents a lethal synergistic interaction with mutations at either da or the X:A ratio, two signals that define the initial activity state of Sxl, while SxlfLS do not. These data suggest that the two complementation groups are related to the two sets of early and late Sxl transcripts, which are responsible for the early and late Sxl functions, respectively: Sxlfb and Sxlfc would affect the early functions and SxlfLS would affect the late Sxl functions.

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