A quasi-elastic light scattering and cinematographical comparison of three strains of motileChlamydomonas reinhardtii: a wild type strain, a colchicine resistant mutant and a backward swimming mutant

1983 ◽  
Vol 4 (3) ◽  
pp. 333-351 ◽  
Author(s):  
T. J. Racey ◽  
F. R. Hallett
Keyword(s):  
Light Scattering ◽  
Type Strain ◽  
Wild Type Strain ◽  
Resistant Mutant ◽  
Wild Type ◽  
Elastic Light Scattering

Sulphide Resistance in the Cyanobacterium Microcystis aeruginosa: a Comparative Study of Morphology and Photosynthetic Performance Between the Sulphide-Resistant Mutant and the Wild-Type Strain

2015 ◽  
Vol 71 (4) ◽  
pp. 860-872 ◽  
Author(s):  
Elena Bañares-España ◽  
María del Mar Fernández-Arjona ◽  
María Jesús García-Sánchez ◽  
Miguel Hernández-López ◽  
Andreas Reul ◽  
...  
Keyword(s):  
Comparative Study ◽  
Microcystis Aeruginosa ◽  
Type Strain ◽  
Wild Type Strain ◽  
Resistant Mutant ◽  
Photosynthetic Performance ◽  
Wild Type

scholarly journals A heat shock-resistant mutant of Saccharomyces cerevisiae shows constitutive synthesis of two heat shock proteins and altered growth.

1984 ◽  
Vol 99 (4) ◽  
pp. 1441-1450 ◽  
Author(s):  
H Iida ◽  
I Yahara
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Heat Shock ◽  
Type Strain ◽  
Wild Type Strain ◽  
Growth Control ◽  
Protein S ◽  
Resistant Mutant ◽  
Wild Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
Sulfur Starvation

A heat shock-resistant mutant of the budding yeast Saccharomyces cerevisiae was isolated at the mutation frequency of 10(-7) from a culture treated with ethyl methane sulfonate. Cells of the mutant are approximately 1,000-fold more resistant to lethal heat shock than those of the parental strain. Tetrad analysis indicates that phenotypes revealed by this mutant segregated together in the ratio 2+:2- from heterozygotes constructed with the wild-type strain of the opposite mating type, and are, therefore, attributed to a single nuclear mutation. The mutated gene in the mutant was herein designated hsr1 (heat shock response). The hsr1 allele is recessive to the HSR1+ allele of the wild-type strain. Exponentially growing cells of hsr1 mutant were found to constitutively synthesize six proteins that are not synthesized or are synthesized at reduced rates in HSR1+ cells unless appropriately induced. These proteins include one hsp/G0-protein (hsp48A), one hsp (hsp48B), and two G0-proteins (p73, p56). Heterozygous diploid (hsr1/HSR1+) cells do not synthesize the proteins constitutively induced in hsr1 cells, which suggests that the product of the HSR1 gene might negatively regulate the synthesis of these proteins. The hsr1 mutation also led to altered growth of the mutant cells. The mutation elongated the duration of G1 period in the cell cycle and affected both growth arrest by sulfur starvation and growth recovery from it. We discuss the problem of which protein(s) among those constitutively expressed in growing cells of the hsr1 mutant is responsible for heat shock resistance and alterations in the growth control.

scholarly journals Effect of Trehalose and Trehalose Transport on the Tolerance ofClostridium perfringensto Environmental Stress in a Wild Type Strain and Its Fluoroquinolone-Resistant Mutant

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Miseon Park ◽  
Wilfrid J. Mitchell ◽  
Fatemeh Rafii
Keyword(s):  
Environmental Stress ◽  
Type Strain ◽  
Wild Type Strain ◽  
Resistant Mutant ◽  
Defined Medium ◽  
Low Ph ◽  
Bacterial Cells ◽  
Chemically Defined Medium ◽  
Wild Type ◽  
Qrt Pcr

Trehalose has been shown to protect bacterial cells from environmental stress. Its uptake and osmoprotective effect inClostridium perfringenswere investigated by comparing wild typeC. perfringensATCC 13124 with a fluoroquinolone- (gatifloxacin-) resistant mutant. In a chemically defined medium, trehalose and sucrose supported the growth of the wild type but not that of the mutant. Microarray data and qRT-PCR showed that putative genes for the phosphorylation and transport of sucrose and trehalose (via phosphoenolpyruvate-dependent phosphotransferase systems, PTS) and some regulatory genes were downregulated in the mutant. The wild type had greater tolerance than the mutant to salts and low pH; trehalose and sucrose further enhanced the osmotolerance of the wild type to NaCl. Expression of the trehalose-specific PTS was lower in the fluoroquinolone-resistant mutant. Protection ofC. perfringensfrom environmental stress could therefore be correlated with the ability to take up trehalose.

scholarly journals Controlling the hypermutation: Exploitation of the MutS protein in Pseudomonas aeruginosa

2020 ◽  
Vol 2 (7A) ◽  
Author(s):  
Yue Yuan On ◽  
Martin Welch
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Type Strain ◽  
Wild Type Strain ◽  
Resistant Mutant ◽  
Inducible Promoter ◽  
Wild Type ◽  
Cdna Analysis ◽  
In The Wild ◽  
Mismatch Recognition ◽  
Muts Gene

Pseudomonas aeruginosa infections commonly develop in individuals with cystic fibrosis (CF), and its adaptation in such an unfavourable condition is always found to be related to hypermutation. In fact, most of the hypermutation is due to the defects in mutS gene which involves in the mismatch repair mechanism, causing the acceleration of mutation rate and adaptive evolution. In order to rheostatically express the MutS protein and achieve “hypomutation” (in which the rate of mutation is lower than that of wild type strain), an exogenous mutS gene with rhamnose-inducible promoter was cloned into MPAO1 mutS::Tn mutant strain. Present findings demonstrate that this system is tightly-controlled and stable, with less rifampicin-resistant mutant frequency and more fluorescence intensity from a GFP-tagged MutS expressing cells were observed when the concentration of the inducer increases. Interestingly, the results from Western blot analysis show that less MutS protein is required to suppress hypermutation in the wild type strain, as compared to our construct that behaves similar to the wild type but obviously needs more MutS expression to achieve such state. This indicates that the exogenous MutS might be lacking of other important protein to work efficiently in mismatch recognition. Therefore, based on our cDNA analysis, we found that fdxA gene next to the mutS gene is in the same operon, which could suggest that they might be functionally related in the DNA repair machinery.

scholarly journals Effects of Mutations of RAD50, RAD51, RAD52, and Related Genes on Illegitimate Recombination in Saccharomyces cerevisiae

Genetics ◽  
1996 ◽  
Vol 142 (2) ◽  
pp. 383-391 ◽  
Author(s):  
Yasumasa Tsukamoto ◽  
Jun-ichi Kato ◽  
Hideo Ikeda
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Quantitative Analysis ◽  
Structural Analysis ◽  
Recombination Rate ◽  
Type Strain ◽  
Negative Selection ◽  
Wild Type Strain ◽  
Illegitimate Recombination ◽  
Wild Type ◽  
In The Wild

Abstract To examine the mechanism of illegitimate recombination in Saccharomyces cerevisiae, we have developed a plasmid system for quantitative analysis of deletion formation. A can1 cyh2 cell carrying two negative selection markers, the CAN1 and CYH2 genes, on a YCp plasmid is sensitive to canavanine and cycloheximide, but the cell becomes resistant to both drugs when the plasmid has a deletion over the CAN1 and CYH2 genes. Structural analysis of the recombinant plasmids obtained from the resistant cells showed that the plasmids had deletions at various sites of the CAN1-CYH2 region and there were only short regions of homology (1-5 bp) at the recombination junctions. The results indicated that the deletion detected in this system were formed by illegitimate recombination. Study on the effect of several rad mutations showed that the recombination rate was reduced by 30-, 10-, 10-, and 10-fold in the rad52, rad50, mre11, and xrs2 mutants, respectively, while in the rud51, 54, 55, and 57 mutants, the rate was comparable to that in the wild-type strain. The rad52 mutation did not affect length of homology at junction sites of illegitimate recombination.

Sign in / Sign up

Export Citation Format

Share Document