Characterization of a norflurazon-resistant mutant of Chlamydomonas reinhardtii

Weed Science ◽  
1997 ◽  
Vol 45 (3) ◽  
pp. 374-377 ◽  
Author(s):  
Varsha Vartak ◽  
Sujata Bhargava
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Mode Of Action ◽  
Resistant Mutant ◽  
Phytoene Desaturase ◽  
Wild Type ◽  
Cross Tolerance ◽  
In The Wild ◽  
Similar Mode ◽  
Target Enzyme

A norflurazon-resistant mutant has been isolated from Chlamydomonas reinhardtii that showed a three-fold factor of resistance over wild type cultures. In comparison to wild type cultures, the mutant showed better retention of chlorophylls and carotenoids when grown in light in the presence of norflurazon. When grown in the dark, chlorophyll losses were similar, while carotenoid losses were lower than in the wild type cultures. Higher levels of phytoene accumulated in the wild type cultures in the presence of norflurazon than in the resistant cultures. The resistant cultures also showed cross tolerance to EMD-IT 5914, a herbicide with a similar mode of action. Norflurazon resistance in this alga appears to arise from alterations in the target enzyme phytoene desaturase.

Characterization of Enterococcus faecium mutants resistant to mundticin KS, a class IIa bacteriocin

Microbiology ◽  
2003 ◽  
Vol 149 (10) ◽  
pp. 2901-2908 ◽  
Author(s):  
Youko Sakayori ◽  
Mizuho Muramatsu ◽  
Satoshi Hanada ◽  
Yoichi Kamagata ◽  
Shinichi Kawamoto ◽  
...  
Keyword(s):  
Enterococcus Faecium ◽  
Antimicrobial Agents ◽  
Wild Type Strain ◽  
Unsaturated Fatty Acids ◽  
Class I ◽  
Wild Type ◽  
Food Preservatives ◽  
In The Wild ◽  
Resistant Mutants

The emergence and spread of mutants resistant to bacteriocins would threaten the safety of using bacteriocins as food preservatives. To determine the physiological characteristics of resistant mutants, mutants of Enterococcus faecium resistant to mundticin KS, a class IIa bacteriocin, were isolated. Two types of mutant were found that had different sensitivities to other antimicrobial agents such as nisin (class I) and kanamycin. Both mutants were resistant to mundticin KS even in the absence of Mg2+ ions. The composition of unsaturated fatty acids in the resistant mutants was significantly increased in the presence of mundticin KS. The composition of the phospholipids in the two resistant mutants also differed from those in the wild-type strain. The putative zwitterionic amino-containing phospholipid in both mutants significantly increased, whereas amounts of phosphatidylglycerol and cardiolipin decreased. These changes in membrane structure may influence resistance of enterococci to class IIa and class I bacteriocins.

scholarly journals Isolation and Characterization of Mutations in theEscherichia coli Regulatory Protein XapR

1999 ◽  
Vol 181 (14) ◽  
pp. 4397-4403 ◽  
Author(s):  
Casper Jørgensen ◽  
Gert Dandanell
Keyword(s):  
Amino Acids ◽  
Purine Nucleoside Phosphorylase ◽  
Mutational Analysis ◽  
Regulatory Protein ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Wild Type ◽  
Isolation And Characterization ◽  
In The Wild

ABSTRACT In this work, the LysR-type protein XapR has been subjected to a mutational analysis. XapR regulates the expression of xanthosine phosphorylase (XapA), a purine nucleoside phosphorylase inEscherichia coli. In the wild type, full expression of XapA requires both a functional XapR protein and the inducer xanthosine. Here we show that deoxyinosine can also function as an inducer in the wild type, although not to the same extent as xanthosine. We have isolated and characterized in detail the mutants that can be induced by other nucleosides as well as xanthosine. Sequencing of the mutants has revealed that two regions in XapR are important for correct interactions between the inducer and XapR. One region is defined by amino acids 104 and 132, and the other region, containing most of the isolated mutations, is found between amino acids 203 and 210. These regions, when modelled into the three-dimensional structure of CysB from Klebsiella aerogenes, are placed close together and are most probably directly involved in binding the inducer xanthosine.

scholarly journals Characterization of gamma irradiation-induced mutations in Arabidopsis mutants deficient in non-homologous end joining

2020 ◽  
Vol 61 (5) ◽  
pp. 639-647
Author(s):  
Yan Du ◽  
Yoshihiro Hase ◽  
Katsuya Satoh ◽  
Naoya Shikazono
Keyword(s):  
Gamma Rays ◽  
Wild Type ◽  
End Joining ◽  
Complex Type ◽  
Single Base ◽  
In The Wild ◽  
Non Homologous End Joining ◽  
Dna Ends ◽  
Wild Type Control

Abstract To investigate the involvement of the non-homologous end joining (NHEJ) pathway in plant mutagenesis by ionizing radiation, we conducted a genome-wide characterization of the mutations induced by gamma rays in NHEJ-deficient Arabidopsis mutants (AtKu70−/− and AtLig4−/−). Although both mutants were more sensitive to gamma rays than the wild-type control, the AtKu70−/− mutant was slightly more sensitive than the AtLig4−/− mutant. Single-base substitutions (SBSs) were the predominant mutations in the wild-type control, whereas deletions (≥2 bp) and complex-type mutations [i.e. more than two SBSs or short insertion and deletions (InDels) separated by fewer than 10 bp] were frequently induced in the mutants. Single-base deletions were the most frequent deletions in the wild-type control, whereas the most common deletions in the mutants were 11–30 bp. The apparent microhomology at the rejoined sites of deletions peaked at 2 bp in the wild-type control, but was 3–4 bp in the mutants. This suggests the involvement of alternative end joining and single-strand annealing pathways involving increased microhomology for rejoining DNA ends. Complex-type mutations comprising short InDels were frequently detected in the mutants, but not in the wild-type control. Accordingly, NHEJ is more precise than the backup pathways, and is the main pathway for rejoining the broken DNA ends induced by ionizing radiation in plants.

Physiological and genetic characterization of the osmotic stress response in Bacillus subtilis

1994 ◽  
Vol 40 (2) ◽  
pp. 140-144 ◽  
Author(s):  
Sandra M. Ruzal ◽  
Carmen Sanchez-Rivas
Keyword(s):  
Bacillus Subtilis ◽  
Osmotic Stress ◽  
Stationary Phase ◽  
Resistant Mutant ◽  
Wild Type ◽  
Osmotic Stress Response ◽  
Mutant Phenotypes ◽  
Physiological Variations ◽  
Growth Adaptation

Bacillus subtilis cultures submitted to an osmotic upshock (1.5 M NaCl) lysed unless stationary phase had been reached. Several physiological variations were observed, such as delayed growth (adaptation), a filamentous bacterial appearance, RecA-dependent osmoresistance (SOS), and cross-induction by a previous stress (heat shock). Osmoresistance and sporulation seem to share pathways of regulation such as inhibition in the presence of glucose and glutamine and derepression in a catabolite-resistant mutant such as degUh. However, spores were not obtained on hypertonic media. Mutants of later sporulation stages (spoII, spoIII) presented a response similar to that of the wild-type parent, indicating that both processes probably shared early controls. Null mutations in any of the known key modulators of sporulation (spoOA or degU) resulted in similar levels of osmosensitivity. Sensor mutations in kinA and degS also led to strains with altered responses, the kinA mutant being even more osmosensitive than the degS mutant. Several spoOA mutant phenotypes are due to this gene's control of abrB, a regulator of stationary-phase events, and an abrB mutation relieved the osmosensitivity of the spoOA-containing mutant but had no effect on a wild-type strain.Key words: Bacillus subtilis, osmotic stress, sporulation.

scholarly journals Biochemical Characterization of Wild-Type and Mutant Isoamylases of Chlamydomonas reinhardtii Supports a Function of the Multimeric Enzyme Organization in Amylopectin Maturation

2001 ◽  
Vol 125 (4) ◽  
pp. 1723-1731 ◽  
Author(s):  
David Dauvillée ◽  
Christophe Colleoni ◽  
Gregory Mouille ◽  
Matthew K. Morell ◽  
Christophe d'Hulst ◽  
...  
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Biochemical Characterization ◽  
Wild Type ◽  
Enzyme Organization

scholarly journals Effects of Chloramphenicol on the Mitochondrial Respiratory Chain in the Wild Strain and in a Cytoplasmic Chloramphenicol-Resistant Mutant ofTetrahymena pyriformis

1982 ◽  
Vol 2 (6) ◽  
pp. 715-719 ◽  
Author(s):  
Roland Perasso ◽  
Jean-Jacques Curgy ◽  
Nicole Stelly ◽  
Jean Andre
Keyword(s):  
Oxygen Consumption ◽  
Cytochrome Oxidase ◽  
Oxidase Activity ◽  
Wild Strain ◽  
Resistant Mutant ◽  
Wild Type ◽  
Mitochondrial Translation ◽  
Cytochrome Oxidase Activity ◽  
In The Wild ◽  
Mitochondrial Respiratory

The effects of chloramphenicol (CAP) on mitochondrial respiratory activity in the wild strain (ST) and in a cytoplasmic CAP-resistant mutant (STR1) ofTetrahymena pyriformiswere studied by determining oxygen consumption, by spectrophotometry, and by cytochemistry. In the absence of CAP both strains had the same respiration capacity, and the low-temperature spectra of their isolated mitochondria were similar. Furthermore, the mitochondria of both strains showed a positive reaction with diaminobenzidine, denoting a similar cytochrome oxidase activity. However, when cells were grown in CAP for 24 or 48 h, the peaks of cytochrome oxidase and cytochromebwere almost absent in the wild type. In this type the oxygen consumption was greatly decreased, and the mitochondria were no longer stained by diaminobenzidine. In the mutant, the peaks of cytochrome oxidase and cytochromebwere decreased only; respiration was less affected than in the wild type, and cytochrome oxidase activity was still disclosed by the diaminobenzidine reaction. These results show that CAP inhibits the synthesis of two cytochromes (band oxidase) which are partially translated into the mitochrondria ofT. pyriformis.In the mutant, CAP reduces only the mitochondrial translation, resulting in reduced mitochondrial activity and reduced growth rate of the cell. These results are compared with the nucleo-mitochondrial regulation mechanisms discussed in our previous works.

scholarly journals Induction and Characterization of Tetraploids from Seeds of Bletilla striata (Thunb.) Reichb.f.

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Meiya Li ◽  
Bin Ding ◽  
Weipeng Huang ◽  
Jieli Pan ◽  
Zhishan Ding ◽  
...  
Keyword(s):  
Genetic Improvement ◽  
Herbal Remedy ◽  
Morphological Characteristics ◽  
Colchicine Treatment ◽  
Endangered Plants ◽  
Wild Type ◽  
Bletilla Striata ◽  
In The Wild

Bletilla striata (Thunb.), an ornamental and medicinal plant, is on the list of endangered plants in China. Its pseudobulb is abundant in polysaccharide and has been used for centuries as a herbal remedy. However, a recent rise in demand has placed it at risk of extinction, and therefore, research on its propagation and genetic improvement is essential. Since polyploids tend to possess advantageous qualities, we incubated B. striata seeds with colchicine with the aim of creating tetraploid plantlets. Aseptic seeds treated with 0.1% colchicine for 7 days showed the highest tetraploid induction rate of 40.67 ± 0.89%. Compared with the wild-type, the tetraploids could be identified by their morphological characteristics including larger stomata at a lower density, larger leaf blades, and a thicker petiole. Contents of polysaccharide and phenolic compounds were also determined in the tetraploid pseudobulbs, revealing significantly higher values than in the wild-type. In vitro colchicine treatment can therefore be used to successfully produce B. striata tetraploids with superior pseudobulbs.

Rapid Identification and Molecular Characterization of Phytoene Desaturase Mutations in Fluridone-Resistant Hydrilla (Hydrilla verticillata)

Weed Science ◽  
2013 ◽  
Vol 61 (1) ◽  
pp. 32-40 ◽  
Author(s):  
Lori K. Benoit ◽  
Donald H. Les
Keyword(s):  
Gene Mutations ◽  
Hydrilla Verticillata ◽  
Rapid Identification ◽  
Phytoene Desaturase ◽  
Wild Type ◽  
Herbicide Resistant ◽  
Rapid Pcr ◽  
Sequencing Method ◽  
The Us

Florida hydrilla populations have shown an alarming increase in resistance to fluridone, an herbicide used extensively for controlling invasive US hydrilla populations. A rapid PCR and sequencing method was developed to identify and screen hydrilla genomic DNA for three previously identified phytoene desaturase (pds) gene mutations that confer resistance to fluridone. Ninety hydrilla accessions were screened for fluridone resistant genotypes including 46 accessions from the US and 44 accessions from 15 other countries. In Florida, hydrilla from five of nine sites tested was heterozygous for wild-type and herbicide-resistant alleles. Additionally, a new resistant population was identified from Lake Seminole in Georgia, the first genetically confirmed strain of resistant hydrilla outside of Florida. All resistance-conferring mutations were located on the same homologous haplotype of US dioecious hydrilla. All other hydrilla samples tested possessed only wild type alleles, including monoecious strains that had been exposed to fluridone. Management implications are discussed.

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