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

Genetics ◽  
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.

scholarly journals The unc-22(IV) region of Caenorhabditis elegans: genetic analysis of lethal mutations.

Genetics ◽  
1988 ◽  
Vol 119 (2) ◽  
pp. 345-353
Author(s):  
D V Clark ◽  
T M Rogalski ◽  
L M Donati ◽  
D L Baillie
Keyword(s):  
Caenorhabditis Elegans ◽  
Linkage Group ◽  
Essential Gene ◽  
Group Iv ◽  
Essential Genes ◽  
Ems Mutagenesis ◽  
Lethal Mutations ◽  
Complementation Groups ◽  
Minimum Estimate ◽  
Caenorhabditis Elegans Genome

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.

scholarly journals Genetic analysis of Saccharomyces cerevisiae chromosome I: on the role of mutagen specificity in delimiting the set of genes identifiable using temperature-sensitive-lethal mutations.

Genetics ◽  
1991 ◽  
Vol 127 (2) ◽  
pp. 279-285 ◽  
Author(s):  
S D Harris ◽  
J R Pringle
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Essential Genes ◽  
Previous Attempt ◽  
Temperature Sensitive ◽  
Molecular Analyses ◽  
Cellular Processes ◽  
Lethal Mutations ◽  
Mutagen Specificity ◽  
Complementation Groups ◽  
Chromosome I

Abstract In a previous attempt to identify as many as possible of the essential genes on Saccharomyces cerevisiae chromosome I, temperature-sensitive (Ts-) lethal mutations that had been induced by ethyl methane-sulfonate or nitrosoguanidine were analyzed. Thirty-two independently isolated mutations that mapped to chromosome I identified only three complementation groups, all of which had been known previously. In contrast, molecular analyses of segments of the chromosome have suggested the presence of numerous additional essential genes. In order to assess the degree to which problems of mutagen specificity had limited the set of genes detected using Ts- lethal mutations, we isolated a new set of such mutations after mutagenesis with UV or nitrogen mustard. Surprisingly, of 21 independently isolated mutations that mapped to chromosome I, 17 were again in the same three complementation groups as identified previously, and two of the remaining four mutations were apparently in a known gene involved in cysteine biosynthesis. Of the remaining two mutations, one was in one of the essential genes identified in the molecular analyses, and the other was too leaky to be mapped. These results suggest that only a minority of the essential genes in yeast can be identified using Ts- lethal mutations, regardless of the mutagen used, and thus emphasize the need to use multiple genetic strategies in the investigation of cellular processes.

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

1987 ◽  
Vol 49 (3) ◽  
pp. 207-213 ◽  
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.

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

Genetics ◽  
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.

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

1998 ◽  
Vol 260 (2-3) ◽  
pp. 280-288 ◽  
Author(s):  
H. I. Stewart ◽  
N. J. O'Neil ◽  
D. L. Janke ◽  
N. W. Franz ◽  
H. M. Chamberlin ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Lethal Mutations ◽  
Complementation Groups ◽  
Chromosome Iii

scholarly journals Genetic organization of the unc-60 region in Caenorhabditis elegans.

Genetics ◽  
1988 ◽  
Vol 118 (1) ◽  
pp. 49-59
Author(s):  
K S McKim ◽  
M F Heschl ◽  
R E Rosenbluth ◽  
D L Baillie
Keyword(s):  
Caenorhabditis Elegans ◽  
Linkage Group ◽  
Gene Order ◽  
Chromosomal Region ◽  
Essential Genes ◽  
Ethyl Methanesulfonate ◽  
Induced Mutations ◽  
Nematode Caenorhabditis Elegans ◽  
Genetic Organization ◽  
Muscle Structure

Abstract We have investigated the chromosomal region around unc-60 V, a gene affecting muscle structure, in the nematode Caenorhabditis elegans. The region studied covers 3 map units and lies at the left end of linkage group (LG) V. Compared to the region around dpy-11 (at the center of LGV), the unc-60 region has relatively few visible genes per map unit. We found the same to be true for essential genes. By screening simultaneously for recessive lethals closely linked to either dpy-11 or unc-60, we recovered ethyl methanesulfonate-induced mutations in 10 essential genes near dpy-11 but in only two genes near unc-60. Four deficiency breakpoints were mapped to the unc-60 region. Using recombination and deficiency mapping we established the following gene order: let-336, unc-34, let-326, unc-60, emb-29, let-426. Regarding unc-60 itself, we compared the effect of ten alleles (including five isolated during this study) on hermaphrodite mobility and fecundity. We used intragenic mapping to position eight of these alleles. The results show that these alleles are not distributed uniformly within the gene, but map to two groups approximately 0.012 map unit apart.

scholarly journals HYPOMORPHIC LETHAL MUTATIONS AND THEIR IMPLICATIONS FOR THE INTERPRETATION OF LETHAL COMPLEMENTATION STUDIES IN DROSOPHILA

Genetics ◽  
1983 ◽  
Vol 105 (4) ◽  
pp. 957-968
Author(s):  
David Nash ◽  
Frank C Janca
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Small Region ◽  
Essential Genes ◽  
Activity Levels ◽  
Lethal Mutations ◽  
Homozygous Mutant ◽  
Complementation Groups ◽  
Interallelic Complementation ◽  
Hypomorphic Alleles

ABSTRACT In a small region of the X chromosome of Drosophila melanogaster, we have found that a third of the mutations that appear to act as lethals in segmental haploids are viable in homozygous mutant individuals. These viable mutations fall into four complementation groups. The most reasonable explanation of these mutations is that they are a subset of functionally hypomorphic alleles of essential genes: hypomorphic mutations with activity levels above a threshold required for survival, but below twice that level, should behave in this manner. We refer to these mutations as "haplo-specific lethal mutations." In studies of autosomal lethals, haplo-specific lethal mutations can be included in lethal complementation tests without being identified as such. Accidental inclusion of disguised haplo-specific lethals in autosomal complementation tests will generate spurious examples of interallelic complementation.

TEMPERATURE-SENSITIVE LETHAL MUTATIONS ON YEAST CHROMOSOME I APPEAR TO DEFINE ONLY A SMALL NUMBER OF GENES

Genetics ◽  
1984 ◽  
Vol 108 (1) ◽  
pp. 67-90
Author(s):  
David B Kaback ◽  
Paul W Oeller ◽  
H Yde Steensma ◽  
Janet Hirschman ◽  
Diane Ruezinsky ◽  
...  
Keyword(s):  
Chromosome Loss ◽  
Temperature Sensitive ◽  
Yeast Saccharomyces Cerevisiae ◽  
Recessive Mutations ◽  
Large Numbers ◽  
Complementation Groups ◽  
Lethal Allele ◽  
Available Information ◽  
Chromosome I ◽  
Ts Mutations

ABSTRACT A method was developed for isolating large numbers of mutations on chromosome I of the yeast Saccharomyces cerevisiae. A strain monosomic for chromosome I (i.e., haploid for chromosome I and diploid for all other chromosomes) was mutagenized with either ethyl methanesulfonate or N-methyl-N'-nitro-N -nitrosoguanidine and screened for temperature-sensitive (Ts-) mutants capable of growth on rich, glucose-containing medium at 25° but not at 37°. Recessive mutations induced on chromosome I are expressed, whereas those on the diploid chromosomes are usually not expressed because of the presence of wild-type alleles on the homologous chromosomes. Dominant ts mutations on all chromosomes should also be expressed, but these appeared rarely. — Of the 41 ts mutations analyzed, 32 mapped on chromosome I. These 32 mutations fell into only three complementation groups, which proved to be the previously described genes CDC15, CDC24 and PYK1 (or CDC19). We recovered 16 or 17 independent mutations in CDC15, 12 independent mutations in CDC24 and three independent mutations in PYK1. A fourth gene on chromosome I, MAK16, is known to be capable of giving rise to a ts-lethal allele, but we recovered no mutations in this gene. The remaining nine mutations isolated using the monosomic strain appeared not to map on chromosome I and were apparently expressed in the original mutants because they had become homozygous or hemizygous by mitotic recombination or chromosome loss. — The available information about the size of chromosome I suggests that it should contain approximately 60-100 genes. However, our isolation in the monosomic strain of multiple, independent alleles of just three genes suggests that only a small proportion of the genes on chromosome I is easily mutable to give a Ts--lethal phenotype. — During these studies, we located CDC24 on chromosome I and determined that it is centromere distal to PYK1 on the left arm of the chromosome.

scholarly journals Combined flow cytometry and high throughput image analysis for the study of essential genes in Caenorhabditis elegans

2017 ◽  
Author(s):  
Blanca Hernando-Rodríguez ◽  
Annmary Paul Erinjeri ◽  
María Jesús Rodríguez-Palero ◽  
Val Millar ◽  
Sara González-Hernández ◽  
...  
Keyword(s):  
Image Analysis ◽  
Caenorhabditis Elegans ◽  
High Throughput ◽  
Rnai Screen ◽  
Essential Genes ◽  
Genetic Interactions ◽  
Automated Image Analysis ◽  
C Elegans ◽  
Larval Stages ◽  
Lethal Mutations

ABSTRACTBackgroundThe advancement in automated image based microscopy platforms coupled with high throughput liquid workflows has facilitated the design of large scale screens utilizing multicellular model organisms such as Caenorhabditis elegans to identify genetic interactions, therapeutic drugs or disease modifiers. However, the analysis of essential genes has lagged behind because lethal or sterile mutations pose a bottleneck for high throughput approaches.ResultsIn C. elegans, non-conditional lethal mutations can be maintained in heterozygosis using chromosome balancers, commonly labelled with GFP in the pharynx. Moreover gene-expression is typically monitored by the use of fluorescent reporters marked with the same fluorophore. Therefore, the separation of the different populations of animals at early larval stages represents a challenge. Here, we develop a sorting strategy capable of selecting homozygous mutants carrying a GFP stress reporter from GFP-balanced animals at early larval stages. Because sorting is not completely error-free, we develop an automated high-throughput image-analysis protocol that identifies and discards animals carrying the chromosome balancer. We demonstrate the experimental usefulness of combining sorting of homozygous lethal mutants and automated image-analysis in a functional genomic RNAi screen for genes that genetically interact with mitochondrial prohibitin (PHB). Lack of PHB results in embryonic lethality, while, homozygous PHB deletion mutants develop into sterile adults due to maternal contribution and strongly induce the mitochondrial unfolded protein response (UPRmt). In a chromosome-wide RNAi screen for C. elegans genes having human orthologues, we uncover both, known and new PHB genetic interactors affecting the UPRmt and growth.ConclusionsA systematic way to analyse genetic interactions of essential genes in multicellular organisms is lacking. The method presented here allows the study of balanced lethal mutations in a high-throughput manner and can be easily adapted depending on the user’s requirements. Therefore, it will serve as a useful resource for the C. elegans community for probing new biological aspects of essential nematode genes as well as the generation of more comprehensive genetic networks.

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