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 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 Characterization of mutations that suppress the temperature-sensitive growth of the hpr1 delta mutant of Saccharomyces cerevisiae.

Genetics ◽  
1994 ◽  
Vol 137 (4) ◽  
pp. 945-956 ◽  
Author(s):  
H Y Fan ◽  
H L Klein
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Synthetic Lethality ◽  
Direct Repeat ◽  
Fold Increase ◽  
Temperature Sensitive ◽  
Rad Genes ◽  
Complementation Groups ◽  
Rad Mutants ◽  
Extragenic Suppressors

Abstract The hpr1 delta 3 mutant of Saccharomyces cerevisiae is temperature-sensitive for growth at 37 degrees and has a 1000-fold increase in deletion of tandem direct repeats. The hyperrecombination phenotype, measured by deletion of a leu2 direct repeat, is partially dependent on the RAD1 and RAD52 gene products, but mutations in these RAD genes do not suppress the temperature-sensitive growth phenotype. Extragenic suppressors of the temperature-sensitive growth have been isolated and characterized. The 14 soh (suppressor of hpr1) mutants recovered represent eight complementation groups, with both dominant and recessive soh alleles. Some of the soh mutants suppress hpr1 hyperrecombination and are distinct from the rad mutants that suppress hpr1 hyperrecombination. Comparisons between the SOH genes and the RAD genes are presented as well as the requirement of RAD genes for the Soh phenotypes. Double soh mutants have been analyzed and reveal three classes of interactions: epistatic suppression of hpr1 hyperrecombination, synergistic suppression of hpr1 hyperrecombination and synthetic lethality. The SOH1 gene has been cloned and sequenced. The null allele is 10-fold increased for recombination as measured by deletion of a leu2 direct repeat.

scholarly journals PTA1, an essential gene of Saccharomyces cerevisiae affecting pre-tRNA processing.

1992 ◽  
Vol 12 (9) ◽  
pp. 3843-3856 ◽  
Author(s):  
J P O'Connor ◽  
C L Peebles
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Gene Product ◽  
Genomic Library ◽  
Essential Gene ◽  
Growth Defect ◽  
Temperature Sensitive ◽  
Putative Open Reading Frame ◽  
Reading Frame ◽  
Trna Processing ◽  
Chromosome I

We have identified an essential Saccharomyces cerevisiae gene, PTA1, that affects pre-tRNA processing. PTA1 was initially defined by a UV-induced mutation, pta1-1, that causes the accumulation of all 10 end-trimmed, intron-containing pre-tRNAs and temperature-sensitive but osmotic-remedial growth. pta1-1 does not appear to be an allele of any other known gene affecting pre-tRNA processing. Extracts prepared from pta1-1 strains had normal pre-tRNA splicing endonuclease activity. pta1-1 was suppressed by the ochre suppressor tRNA gene SUP11, indicating that the pta1-1 mutation creates a termination codon within a protein reading frame. The PTA1 gene was isolated from a genomic library by complementation of the pta1-1 growth defect. Episome-borne PTA1 directs recombination to the pta1-1 locus. PTA1 has been mapped to the left arm of chromosome I near CDC24; the gene was sequenced and could encode a protein of 785 amino acids with a molecular weight of 88,417. No other protein sequences similar to that of the predicted PTA1 gene product have been identified within the EMBL or GenBank data base. Disruption of PTA1 near the carboxy terminus of the putative open reading frame was lethal. Possible functions of the PTA1 gene product are discussed.

scholarly journals Toward a Comprehensive Temperature-Sensitive Mutant Repository of the Essential Genes of Saccharomyces cerevisiae

2008 ◽  
Vol 30 (2) ◽  
pp. 248-258 ◽  
Author(s):  
Shay Ben-Aroya ◽  
Candice Coombes ◽  
Teresa Kwok ◽  
Kathryn A. O'Donnell ◽  
Jef D. Boeke ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Essential Genes ◽  
Temperature Sensitive ◽  
Sensitive Mutant ◽  
Temperature Sensitive Mutant

scholarly journals Temperature-Sensitive Lethal Pseudorevertants of ste Mutations in Saccharomyces cerevisiae

Genetics ◽  
1987 ◽  
Vol 115 (4) ◽  
pp. 627-636
Author(s):  
Margaret E Katz ◽  
Jill Ferguson ◽  
Steven I Reed
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Complementation Group ◽  
Temperature Sensitive ◽  
G1 Arrest ◽  
Pheromone Response ◽  
Cycle Arrest ◽  
Homogeneous Cell ◽  
Complementation Groups ◽  
Mutant Cells

ABSTRACT A procedure was devised to isolate mutations that could restore conjugational competence to temperature sensitive ste mutants and simultaneously confer temperature-sensitive lethal growth phenotypes. Three such mutations, falling into two complementation groups, were identified on the basis of suppression of ste5 alleles. These same mutations were later shown to be capable of suppressing ste4 and ste7 alleles. Five mutations in a single complementation group were isolated as suppressors of ste2 alleles. None of the mutations described in this study conferred a homogeneous cell cycle arrest phenotype, and all were shown to define complementation groups distinct from those previously identified in studies of cell division cycle (cdc) mutations. In no instance did pseudoreversion appear to be achieved by mutational G1 arrest of ste mutant cells. Instead, it is proposed that the mutations restore conjugation by reestablishing the normal pheromone response.

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 Molecular analysis of Saccharomyces cerevisiae chromosome I: identification of additional transcribed regions and demonstration that some encode essential functions.

Genetics ◽  
1991 ◽  
Vol 127 (2) ◽  
pp. 287-298 ◽  
Author(s):  
B E Diehl ◽  
J R Pringle
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Molecular Analysis ◽  
Unknown Function ◽  
Genetic Studies ◽  
Classical Genetic ◽  
Lethal Mutations ◽  
Integrative Transformation ◽  
Transformation Methods ◽  
Chromosome I ◽  
Detailed Molecular Analysis

Abstract Saccharomyces cerevisiae chromosome I has provided a vivid example of the "gene-number paradox." Although molecular studies have suggested that there are greater than 100 transcribed regions on the chromosome, classical genetic studies have identified only about 15 genes, including just 6 identified in intensive studies using Ts- lethal mutations. To help elucidate the reasons for this disparity, we have undertaken a detailed molecular analysis of a 34-kb segment of the left arm of the chromosome. This segment contains the four known genes CDC24, WHI1, CYC3 and PYK1 plus at least seven transcribed regions of unknown function. The 11 identified transcripts have a total length of approximately 25.9 kb, suggesting that greater than or equal to 75% of the DNA in this region is transcribed. Of the transcribed regions of unknown function, three are essential for viability on rich medium and three appear to be nonessential, as judged by the lethality or nonlethality of deletions constructed using integrative transformation methods. No obvious phenotypes were associated with the deletions in the apparently nonessential genes. However, two of these genes may have homologs elsewhere in the genome, as judged from the appearance of additional bands when DNA-DNA blot hybridizations were performed at reduced stringency. Taken together, the results provide further evidence that the limitations of classical genetic studies of chromosome I cannot be explained solely by a lack of genes, or even a lack of essential genes, on the chromosome.

scholarly journals Potential RNA Binding Proteins in Saccharomyces cerevisiae Identified as Suppressors of Temperature-Sensitive Mutations in NPL3

Genetics ◽  
1996 ◽  
Vol 142 (1) ◽  
pp. 103-115 ◽  
Author(s):  
Michael Henry ◽  
Christina Z Borland ◽  
Mark Bossie ◽  
Pamela A Silver
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Import ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Temperature Sensitive ◽  
Yeast Saccharomyces Cerevisiae ◽  
Heterogeneous Nuclear Ribonucleoproteins ◽  
Rna Export ◽  
Complementation Groups ◽  
Export Protein

The NPL3 gene of the yeast Saccharomyces cerevisiae encodes a protein with similarity to heterogeneous nuclear ribonucleoproteins (hnRNPs). Npl3p has been implicated in many nuclear-related events including RNA export, protein import, and rRNA processing. Several temperature-sensitive alleles of NPL3 have been isolated. We now report the sequence of these alleles. For one allele, npl3-1, four complementation groups of suppressors have been isolated. The cognate genes for the two recessive mutants were cloned. One of these is the previously known RNA15, which, like NPL3, also encodes a protein with similarity to the vertebrate hnRNP A/B protein family. The other suppressor corresponds to a newly defined gene we term HRP1, which also encodes a protein with similarity to the hnRNP A/B proteins of vertebrates. Mutations in HRP1 suppress all npl3 temperature-sensitive alleles but do not bypass an npl3 null allele. We show that HRP1 is essential for cell growth and that the corresponding protein is located in the nucleus. The discovery of two hnRNP homologues that can partially suppress the function of Npl3p, also an RNA binding protein, will be discussed in terms of the possible roles for Npl3p in RNA metabolism.

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.

scholarly journals Cycloheximide-resistant temperature-sensitive lethal mutations of Saccharomyces cerevisiae.

Genetics ◽  
1988 ◽  
Vol 119 (2) ◽  
pp. 303-315
Author(s):  
J H McCusker ◽  
J E Haber
Keyword(s):  
Inhibitory Concentration ◽  
Temperature Sensitive ◽  
Nonpermissive Temperature ◽  
Wild Type ◽  
Lethal Mutations ◽  
New Methods ◽  
Similar Temperature ◽  
Complementation Groups ◽  
Wild Type Yeast

Abstract We describe the isolation and preliminary characterization of a set of pleiotropic mutations resistant to the minimum inhibitory concentration of cycloheximide and screened for ts (temperature-sensitive) growth. These mutations fall into 22 complementation groups of cycloheximide resistant ts lethal mutations (crl). None of the crl mutations appears to be allelic with previously isolated mutations. Fifteen of the CRL loci have been mapped. At the nonpermissive temperature (37 degrees), these mutants arrest late in the cell cycle after several cell divisions. Half of these mutants are also unable to grow at very low temperatures (5 degrees). Although mutants from all of the 22 complementation groups exhibit similar temperature-sensitive phenotypes, an extragenic suppressor of the ts lethality of crl3 does not relieve the ts lethality of most other crl mutants. A second suppressor mutation allows crl10, crl12, and crl14 to grow at 37 degrees but does not suppress the ts lethality of the remaining crl mutants. We also describe two new methods for the enrichment of auxotrophic mutations from a wild-type yeast strain.

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