scholarly journals ISOLATION AND CHARACTERIZATION OF CONDITIONAL ALLELES OF BACTERIOPHAGE T4 GENES uvsX AND uvsY

Genetics ◽  
1984 ◽  
Vol 107 (4) ◽  
pp. 505-523
Author(s):  
Mark A Conkling ◽  
John W Drake
Keyword(s):  
Bacteriophage T4 ◽  
Null Alleles ◽  
Chain Elongation ◽  
Complementation Test ◽  
Temperature Sensitive ◽  
Isolation And Characterization ◽  
Defect Sensitivity ◽  
Dna Chain ◽  
Ionizing Radiations

ABSTRACT The bacteriophage T4 uvsW, uvsX and uvsY gene functions are required for wild-type levels of recombination and for normal survival and mutagenesis after treatments with ultraviolet (UV) and ionizing radiations. The ability of uvsX and uvsY mutations to suppress the lethality of gene 49 mutations was used to select temperature-sensitive and amber alleles of these two genes. (uvsW mutations do not suppress gene 49 mutations.) A simple and powerful complementation test was developed to assist in assigning uvs mutations to genes. The amber alleles of uvsX and uvsY behave as simple null alleles, fully suppressing a gene 49 defect, enhancing UV killing and abolishing UV mutagenesis. However, the properties of the ts alleles of uvsX and uvsY demonstrated that suppression of a gene 49 defect, sensitivity to UV-induced inactivation and UV mutability can be partially uncoupled. These results prompt the hypothesis that radiation mutagenesis occurs during DNA chain elongation past template damage within a recombinational intermediate rather than within a conventional replication fork.

scholarly journals Isolation and characterization of extragenic suppressors of mutations in the SSA hsp70 genes of Saccharomyces cerevisiae.

Genetics ◽  
1992 ◽  
Vol 131 (2) ◽  
pp. 277-285 ◽  
Author(s):  
R J Nelson ◽  
M F Heschl ◽  
E A Craig
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Stress Response ◽  
Regulatory Protein ◽  
Null Alleles ◽  
Temperature Sensitive ◽  
Gene Encoding ◽  
Isolation And Characterization ◽  
Transcriptional Regulatory ◽  
Extragenic Suppressors

Abstract Saccharomyces cerevisiae strains that contain null alleles of two hsp70 genes, SSA1 and SSA2, are temperature sensitive for growth. In this study, extragenic suppressors of ssa1 ssa2 have been isolated. Suppression is due to mutations at nuclear loci designated EXA1, EXA2 and EXA3 for EXtragenic suppressor hsp70 subfamily A. Two of the four EXA1 alleles are dominant as is EXA3-1. The other two EXA1 alleles as well as the sole EXA2 allele are recessive. EXA1 mutations lead to accumulation of a previously uncharacterized form of hsp70. EXA2 and EXA3 mutations affect the regulation of the stress response. In exa2-1 ssa1 ssa2 strains the gene products of the remaining SSA hsp70 genes, SSA3 and SSA4 (Ssa3/4p), accumulate to higher levels. The EXA3-1 mutation results in increased accumulation of both Ssa3/4p and the hsp70s encoded by the SSB1 and SSB2 genes (Ssb1/2p), suggesting that the EXA3 gene product plays a central role in the yeast stress response. Consistent with this hypothesis, EXA3-1 is tightly linked to HSF1, the gene encoding the transcriptional regulatory protein known as "heat shock factor." All of the genes identified in this study seem to be involved in regulating the expression of SSA3 and SSA4 or the activity of their protein products.

Isolation and characterization of a variant myoblast cell line that is temperature sensitive for differentiation

1988 ◽  
Vol 8 (6) ◽  
pp. 2335-2341
Author(s):  
R J Akhurst ◽  
N B Flavin ◽  
J Worden
Keyword(s):  
Cell Line ◽  
Progenitor Cell ◽  
Temperature Shift ◽  
Temperature Sensitive ◽  
Isolation And Characterization ◽  
New Variant ◽  
Myoblast Cell Line ◽  
Myoblast Cell ◽  
Progenitor Cell Line

A new variant rat myogenic cell line, ts485, was isolated by subcloning the cell line ts3b2 (H. T. Nguyen, R. M. Medford, and B. Nadal-Ginard, Cell 34:281-293, 1983). Unlike the progenitor cell line, ts485 was thermosensitive for differentiation. Experiments with conditioned medium suggested that diffusible extracellular factors were not involved in dictating the differential phenotypes of ts485 cells cultured at the permissive and nonpermissive temperatures. Temperature shift experiments performed on cultures of ts485 cells indicated that the temperature-sensitive lesion was in a factor active during the growth phase and required to trigger a cascade of events leading to terminal differentiation.

scholarly journals Isolation and characterization of a molecular chaperone, gp57A, of bacteriophage T4.

1997 ◽  
Vol 179 (6) ◽  
pp. 1846-1851 ◽  
Author(s):  
T Matsui ◽  
B Griniuviené ◽  
E Goldberg ◽  
A Tsugita ◽  
N Tanaka ◽  
...  
Keyword(s):  
Molecular Chaperone ◽  
Bacteriophage T4 ◽  
Isolation And Characterization
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