Potassium transport in Chlamydomonas reinhardtii: isolation and characterization of transport-deficient mutant strains

Planta ◽  
1985 ◽  
Vol 163 (2) ◽  
pp. 208-213 ◽  
Author(s):  
L. D. Polley ◽  
D. D. Doctor
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Potassium Transport ◽  
Deficient Mutant ◽  
Isolation And Characterization ◽  
Mutant Strains

scholarly journals Isolation and characterization of the SPT2 gene, a negative regulator of Ty-controlled yeast gene expression.

1985 ◽  
Vol 5 (7) ◽  
pp. 1543-1553 ◽  
Author(s):  
G S Roeder ◽  
C Beard ◽  
M Smith ◽  
S Keranen
Keyword(s):  
Gene Product ◽  
Regulatory Region ◽  
Negative Regulator ◽  
Transcriptional Level ◽  
Wild Type ◽  
Isolation And Characterization ◽  
Mutant Strains ◽  
Insertion Mutations ◽  
His4 Gene

The his4-917 mutation of Saccharomyces cerevisiae results from the insertion of the Ty element Ty917 into the regulatory region of the HIS4 gene and renders the cell His-. The hist4-912 delta mutant, which carries a solo delta in the 5'-noncoding region of HIS4, is His+ at 37 degrees C but His- at 23 degrees C. Both these mutations interfere with HIS4 expression at the transcriptional level. The His- phenotype of both insertion mutations is suppressed by mutations at the SPT2 locus. The product of the wild-type SPT2 gene apparently represses HIS4 transcription in these mutant strains; this repression is relieved when the SPT2 gene is destroyed by mutation. The repression of transcription by SPT2 presumably results from an interaction between the SPT2+ gene product and Ty or delta sequences. In this paper, we report the cloning and DNA sequence analysis of the wild-type SPT2 gene and show that the gene is capable of encoding a protein of 333 amino acids in length. In addition, we show that a dominant mutation of the SPT2 gene results from the generation of an ochre codon which is presumed to lead to a shortened SPT2 gene product.

scholarly journals Isolation and Characterization of NaCl-Sensitive Mutants of Caulobacter crescentus

2003 ◽  
Vol 69 (6) ◽  
pp. 3029-3035 ◽  
Author(s):  
Luiz Fernando G. Zuleta ◽  
Val�ria C. S. Italiani ◽  
Marilis V. Marques
Keyword(s):  
Caulobacter Crescentus ◽  
Osmotic Shock ◽  
Promoter Regions ◽  
Isolation And Characterization ◽  
Lipopolysaccharide Biosynthesis ◽  
Severe Reduction ◽  
Mutant Strains ◽  
High Concentrations ◽  
Severe Growth

ABSTRACT An attempt to characterize Caulobacter crescentus genes important for the response to high concentrations of NaCl was initiated by the isolation of mutants defective in survival in the presence of 85 mM NaCl. A transposon Tn5 library was screened, and five strains which contained different genes disrupted by the transposon were isolated. Three of the mutants had the Tn5 in genes involved in lipopolysaccharide biosynthesis, one had the Tn5 in the nhaA gene, which encodes a Na+/H+ antiporter, and one had the Tn5 in the ppiD gene, which encodes a peptidyl-prolyl cis-trans isomerase. All the mutant strains showed severe growth arrest in the presence of 85 mM NaCl, but only the nhaA mutant showed decreased viability under these conditions. All the mutants except the nhaA mutant showed a slightly reduced viability in the presence of 40 mM KCl, but all the strains showed a more severe reduction in viability in the presence of 150 mM sucrose, suggesting that they are defective in responding to osmotic shock. The promoter regions of each disrupted gene were cloned in lacZ reporter vectors, and the pattern of expression in response to NaCl and sucrose was determined; this showed that both agents induced ppiD and nhaA gene expression but did not induce the other genes. Furthermore, the ppiD gene was not induced by heat shock, indicating that it does not belong to the σ32 regulon, as opposed to what was observed for its Escherichia coli homolog.

scholarly journals In Vitro Isolation and Characterization of Oxazolidinone-Resistant Mycobacterium tuberculosis

2017 ◽  
Vol 61 (10) ◽  
Author(s):  
Matthew B. McNeil ◽  
Devon D. Dennison ◽  
Catherine D. Shelton ◽  
Tanya Parish
Keyword(s):  
Mycobacterium Tuberculosis ◽  
23S Rrna ◽  
Clinical Settings ◽  
Content Type ◽  
Isolation And Characterization ◽  
Mutant Strains ◽  
Ribosomal Protein L3 ◽  
Resistant Strains

ABSTRACT Oxazolidinones are promising candidates for the treatment of Mycobacterium tuberculosis infections. We isolated linezolid-resistant strains from H37Rv (Euro-American) and HN878 (East-Asian) strains; resistance frequencies were similar in the two strains. Mutations were identified in ribosomal protein L3 (RplC) and the 23S rRNA (rrl). All mutant strains were cross resistant to sutezolid; a subset was cross resistant to chloramphenicol. Mutations in rrl led to growth impairment and decreased fitness that may limit spread in clinical settings.

scholarly journals Isolation and characterization of a restriction and modification deficient mutant ofBrevibacterium lactofermentum

1990 ◽  
Vol 72 (1-2) ◽  
pp. 143-146 ◽  
Author(s):  
Sylvie Bonnassie ◽  
Jacqueline Oreglia ◽  
Annie Trautwetter ◽  
Armand Michel Sicard
Keyword(s):  
Deficient Mutant ◽  
Isolation And Characterization
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