INCREASED FREQUENCY OF AUXOTROPHIC MUTANTS OF USTILAGO HORDEI AFTER COMBINED UV IRRADIATION AND INOSITOL STARVATION

1972 ◽  
Vol 14 (4) ◽  
pp. 785-788 ◽  
Author(s):  
P. L. Thomas
Keyword(s):  
Uv Irradiation ◽  
Wild Type ◽  
Auxotrophic Mutants ◽  
Ustilago Hordei

Auxotrophic mutants of Ustilago hordei were recovered after UV irradiation of a wild-type culture, inositol starvation of an inositol-requiring culture and a combination of the two methods. 1.9% of the survivors of UV irradiation followed by inositol starvation were found to carry a requirement additional to inositol. Inositol starvation by itself gave only 0.27% recovery while UV irradiation alone was even less efficient.

scholarly journals Survival and mutant production induced by mutagenic agents in Metarhizium anisopliae

1995 ◽  
Vol 52 (3) ◽  
pp. 548-554 ◽  
Author(s):  
V. Kava - Cordeiro ◽  
E.A. Luna - Alves - Lima ◽  
J.L. Azevedo
Keyword(s):  
Gamma Radiation ◽  
Ultraviolet Light ◽  
Metarhizium Anisopliae ◽  
Entomopathogenic Fungus ◽  
Nitrous Acid ◽  
Wild Strain ◽  
Wild Type ◽  
Survival Curves ◽  
Auxotrophic Mutants ◽  
Morphological Mutants

A wild strain of Metarhizium anisopliae, an entomopathogenic fungus, was submitted to three mutagenic agents: gamma radiation, ultraviolet light and nitrous acid. Survival curves were obtained and mutants were selected using different mutagenic doses which gave 1 to 5% survival. Morphological and auxotrophic mutants were isolated. Morphological mutants were grouped in a class with yellow conidia and other with pale vinaceous conidia as opposed to the green wild type conidia. Auxotrophic mutants had requirements for vitamin and aminoacid biosynthesis. More than 58% of the total auxotrophk mutants required proline/aipnine. Gamma radiation showed to be the most efficient mutagenic agent giving 0.2% of auxotrophk mutants followed by ultraviolet light (0.12%) and nitrous acid (0.06%).The conidial colour and auxotrophk mutants isolated until now from M. anisopliae were reviewed.

Involvement of the cgtA gene function in stimulation of DNA repair in Escherichia coli and Vibrio harveyi

Microbiology ◽  
2003 ◽  
Vol 149 (7) ◽  
pp. 1763-1770 ◽  
Author(s):  
Ryszard Zielke ◽  
Aleksandra Sikora ◽  
Rafał Dutkiewicz ◽  
Grzegorz Wegrzyn ◽  
Agata Czyż
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Dna Repair ◽  
Gene Product ◽  
Uv Irradiation ◽  
Vibrio Harveyi ◽  
Bacterial Species ◽  
Wild Type ◽  
E Coli ◽  
Stimulation Of

CgtA is a member of the Obg/Gtp1 subfamily of small GTP-binding proteins. CgtA homologues have been found in various prokaryotic and eukaryotic organisms, ranging from bacteria to humans. Nevertheless, despite the fact that cgtA is an essential gene in most bacterial species, its function in the regulation of cellular processes is largely unknown. Here it has been demonstrated that in two bacterial species, Escherichia coli and Vibrio harveyi, the cgtA gene product enhances survival of cells after UV irradiation. Expression of the cgtA gene was found to be enhanced after UV irradiation of both E. coli and V. harveyi. Moderate overexpression of cgtA resulted in higher UV resistance of E. coli wild-type and dnaQ strains, but not in uvrA, uvrB, umuC and recA mutant hosts. Overexpression of the E. coli recA gene in the V. harveyi cgtA mutant, which is very sensitive to UV light, restored the level of survival of UV-irradiated cells to the levels observed for wild-type bacteria. Moreover, the basal level of the RecA protein was lower in a temperature-sensitive cgtA mutant of E. coli than in the cgtA + strain, and contrary to wild-type bacteria, no significant increase in recA gene expression was observed after UV irradiation of this cgtA mutant. Finally, stimulation of uvrB gene transcription under these conditions was impaired in the V. harveyi cgtA mutant. All these results strongly suggest that the cgtA gene product is involved in DNA repair processes, most probably by stimulation of recA gene expression and resultant activation of RecA-dependent DNA repair pathways.

scholarly journals Construction of wild-type Yarrowia lipolytica IMUFRJ 50682 auxotrophic mutants using dual CRISPR/Cas9 strategy for novel biotechnological approaches

2020 ◽  
Vol 140 ◽  
pp. 109621
Author(s):  
Camilla Pires de Souza ◽  
Bernardo Dias Ribeiro ◽  
Maria Alice Zarur Coelho ◽  
Rodrigo Volcan Almeida ◽  
Jean-Marc Nicaud
Keyword(s):  
Yarrowia Lipolytica ◽  
Wild Type ◽  
Auxotrophic Mutants

Color mutants in Cochliobolus carbonum

1972 ◽  
Vol 50 (6) ◽  
pp. 1283-1285 ◽  
Author(s):  
K. J. Leonard
Keyword(s):  
Uv Irradiation ◽  
Mating Type ◽  
Wild Type ◽  
Cochliobolus Carbonum ◽  
Independent Origin ◽  
Induced Mutant

One spontaneous and 31 ultraviolet-induced albino mutants of apparently independent origin of Cochliobolus carbonum Nelson were shown to be alleles or, at least, very closely linked. One spontaneous and one ultraviolet-induced mutant at a second locus conditioned the production of brown rather than black conidia. A third type of mutant induced by ultraviolet (uv.) irradiation produced visible quantities of a diffusible, lavender pigment. The lavender locus appeared to be loosely linked to the albino (40 crossover units) and the brown conidia (38 crossover units) loci. The mating type alleles segregated independently of the three loci affecting color.Albino mutants produced fewer and less well-developed perithecia in matings than did the wild-type isolates from which they were derived. Perithecia of the brown conidia mutants could not be distinguished from wild-type perithecia.

scholarly journals Episomic suppression of phenotype in Salmonella

1964 ◽  
Vol 5 (2) ◽  
pp. 269-281 ◽  
Author(s):  
P. F. Smith-Keary ◽  
G. W. P. Dawson
Keyword(s):  
Gene Expression ◽  
Salmonella Typhimurium ◽  
Uv Irradiation ◽  
Complementation Group ◽  
Wild Type ◽  
Complementation Groups

1. An auxotroph of Salmonella typhimurium, pro-401, was isolated in a strain that was unstable at the su-leuA locus. The auxotrophy of pro-401 is probably due to the attachment of a controlling episome to the proline region of the genome where it suppresses gene expression.2. The controlling episome frequently transposes over short distances so that all clones consist of cells, mixed for the site at which the controlling episome is attached; homologous transductions yield prototrophs.3. The controlling episome can transpose to a different complementation group; homologous transductions yield abortive transductants; syntrophism occurs between cells that are ‘mutant’ in different complementation groups to give reversions consisting entirely of auxotrophic cells which are called auxotrophic reversions.4. The controlling episome transposes over very short distances and never to beyond the limits of this proline region of the genome; no wild-type reversions were found.5. The controlling episome can be located at relatively distant proline sites in different clones; prototrophs from transductions between clones that are separated by many subculturings can be 100 times more frequent than from homologous transductions.6. The controlling episome has its frequency of transposition to different complementation groups increased by UV; irradiation increases the frequency of auxotrophic reversions.7. The controlling episome continues to transpose in stored cells.8. The pattern of reversions of pro-401 is different in these studies from its pattern two years previously. This is discussed.

scholarly journals TolC-Dependent Exclusion of Porphyrins in Escherichia coli

2008 ◽  
Vol 190 (18) ◽  
pp. 6228-6233 ◽  
Author(s):  
Ryoko Tatsumi ◽  
Masaaki Wachi
Keyword(s):  
Escherichia Coli ◽  
Uv Irradiation ◽  
High Performance ◽  
Aminolevulinic Acid ◽  
Wild Type ◽  
E Coli ◽  
Chromatography Analysis ◽  
Increased Sensitivity ◽  
Mutant Cells ◽  
Reddish Brown Color

ABSTRACT We found that Escherichia coli tolC mutants showed increased sensitivity to 5-aminolevulinic acid (ALA), a precursor of porphyrins. The tolC mutant cells grown in the presence of ALA showed a reddish brown color under visible light and a strong red fluorescence under near-UV irradiation. Fluorescence spectrometry and high-performance liquid chromatography analysis showed that the tolC mutant cells grown in the presence of ALA accumulated a large amount of coproporphyrin(ogen) intracellularly. In contrast, the wild-type cells produced coproporphyrin extracellularly. The tolC mutant cells grown in the presence of ALA, which were capable of surviving in the dark, were killed by near-UV irradiation, suggesting that the intracellular coproporphyrin(ogen) renders these cells photosensitive. These results suggest that the TolC-dependent efflux system is involved in the exclusion of porphyrin(ogen)s in E. coli.

scholarly journals LINKAGE OF MUTATIONS AFFECTING MINUS FLAGELLAR MEMBRANE AGGLUTINABILITY TO THE mt  - MATING-TYPE LOCUS OF CHLAMYDOMONAS

Genetics ◽  
1981 ◽  
Vol 99 (1) ◽  
pp. 41-47 ◽  
Author(s):  
Carol J Hwang ◽  
Brian C Monk ◽  
Ursula W Goodenough
Keyword(s):  
Uv Irradiation ◽  
Mating Type ◽  
Zygote Formation ◽  
Wild Type ◽  
Tetrad Analysis ◽  
Type Locus ◽  
Mating Type Locus ◽  
Flagellar Membrane ◽  
Mutant Strains

ABSTRACT Two independently isolated mutant strains, imp-10 and imp-12, were obtained by UV irradiation of wild-type mating-type minus (wt-). Each fails to agglutinate sexually with gametes of either mating type, but mating and zygote formation can be elicited by agglutinating either strain to wt+ gametes by means of anti-flagellar antiserum. Tetrad analysis of the resultant zygotes shows that both imp-10 and imp-12 are very closely linked to mt  -, with no recombinants observed. Diploid strains constructed between imp-10 or imp-12 and wt+ gametes are wt-, that is, they agglutinate and fuse like normal minus cells. Tetrad analysis of triploids from imp-10 diploid x wt+ haploid crosses shows that only imp-10 and wt+ products are recovered. A model is proposed to account for these results.

Inaktivierende und mutagene Wirkung salpetriger Säure auf Zellen von Escherichia coli

1959 ◽  
Vol 14 (8-9) ◽  
pp. 528-537 ◽  
Author(s):  
F. Kaudewitz
Keyword(s):  
Escherichia Coli ◽  
Nitrous Acid ◽  
Single Cells ◽  
Wild Type ◽  
Inactivation Curve ◽  
E Coli ◽  
Auxotrophic Mutants ◽  
Induced Mutants ◽  
Mutagene Wirkung ◽  
Cellular Dna

Cells of E. coli B incubated with NaNO2 undergo inactivation. In non-metabolizing cells the inactivation follows a two hit curve. In metabolizing cells the rate of inactivation is increased and the inactivation curve does not show two-hit kinetics. The rate of inactivation decreases with rising pH and decreasing NaNO2-concentration. Therefore nitrous acid appears to be the active substance.Nitrous acid proved to be a potent mutagen as shown by isolation of auxotrophic mutants. With an inactivation rate of 10-4 about 1.4 per cent of the surviving cells were auxotrophs. The probability that this increase in mutants may be due to selection during inactivation of auxotrophs present before exposure was excluded experimentally. In none of 559 auxotrophic colonies grown from single cells which had survived contact with nitrous acid wild-type sectors were found. For metabolizing and nonmetabolizing cells the increase of the percentage of auxotrophic mutants with increasing time of exposure to HNO2 followed a two-hit curve. In these experiments the percentage of induced mutants was independent of the different rate of inactivation caused by different states of metabolism and dependent only on the time of incubation with nitrous acid. The results are discussed as being in agreement with the assumption that in non-metabolizing cells nitrous acid acts directly on the cellular DNA leading to inactivation and mutation.

scholarly journals Calcium and S100B Regulation of p53-Dependent Cell Growth Arrest and Apoptosis

1998 ◽  
Vol 18 (7) ◽  
pp. 4272-4281 ◽  
Author(s):  
Christian Scotto ◽  
Jean Christophe Deloulme ◽  
Denis Rousseau ◽  
Edmond Chambaz ◽  
Jacques Baudier
Keyword(s):  
Cell Growth ◽  
Uv Irradiation ◽  
Growth Arrest ◽  
Nuclear Accumulation ◽  
Permissive Temperature ◽  
Wild Type ◽  
Cell Growth Arrest ◽  
Calcium Dependent ◽  
Inhibition Of Growth ◽  
Dependent Cell

ABSTRACT In glial C6 cells constitutively expressing wild-type p53, synthesis of the calcium-binding protein S100B is associated with cell density-dependent inhibition of growth and apoptosis in response to UV irradiation. A functional interaction between S100B and p53 was first demonstrated in p53-negative mouse embryo fibroblasts (MEF cells) by sequential transfection with the S100B and the temperature-sensitive p53Val135 genes. We show that in MEF cells expressing a low level of p53Val135, S100B cooperates with p53Val135 in triggering calcium-dependent cell growth arrest and cell death in response to UV irradiation at the nonpermissive temperature (37.5°C). Calcium-dependent growth arrest of MEF cells expressing S100B correlates with specific nuclear accumulation of the wild-type p53Val135 conformational species. S100B modulation of wild-type p53Val135 nuclear translocation and functions was confirmed with the rat embryo fibroblast (REF) cell line clone 6, which is transformed by oncogenic Ha-ras and overexpression of p53Val135. Ectopic expression of S100B in clone 6 cells restores contact inhibition of growth at 37.5°C, which also correlates with nuclear accumulation of the wild-type p53Val135 conformational species. Moreover, a calcium ionophore mediates a reversible G1 arrest in S100B-expressing REF (S100B-REF) cells at 37.5°C that is phenotypically indistinguishable from p53-mediated G1arrest at the permissive temperature (32°C). S100B-REF cells proceeding from G1 underwent apoptosis in response to UV irradiation. Our data support a model in which calcium signaling and S100B cooperate with the p53 pathways of cell growth inhibition and apoptosis.

scholarly journals Aspects of glycine and serine biosynthesis during growth of Pseudomonas AM1 on C1 compounds

1971 ◽  
Vol 121 (5) ◽  
pp. 763-769 ◽  
Author(s):  
W. Harder ◽  
J. R. Quayle
Keyword(s):  
Serine Hydroxymethyltransferase ◽  
Aminotransferase Activity ◽  
Wild Type ◽  
Amino Groups ◽  
Auxotrophic Mutants ◽  
Wild Type Phenotype ◽  
Glyoxylate Aminotransferase ◽  
Serine Biosynthesis

1. Methanol or formate can replace serine or glycine as supplements for growth on succinate of the auxotrophic mutants 20S and 82G of Pseudomonas AM1, showing that the organism can synthesize glycine and serine in net fashion from C1 units. 2. Double mutants of Pseudomonas 20S and 82G have been prepared (20ST-1 and 82GT-1) that are unable to grow on succinate+1mm-glyoxylate, succinate+2mm-methanol or methanol alone. 3. Mutants 20ST-1 and 82GT-1 lacked serine–glyoxylate aminotransferase activity, and revertants to the phenotype of 20S and 82G regained serine–glyoxylate aminotransferase activity. A total revertant of 82GT-1 to wild-type phenotype regained activities of serine hydroxymethyltransferase and serine–glyoxylate aminotransferase. 4. The activity of serine–glyoxylate aminotransferase in methanol-grown Pseudomonas AM1 is eightfold higher than in the succinate-grown organism. 5. The combined results show that in Pseudomonas AM1 serine–glyoxylate aminotransferase is necessary for growth on C1 compounds and is involved in the conversion of methanol into glycine via glyoxylate. 6. It is suggested that the phosphorylated pathway of serine biosynthesis from phosphoglycerate replenishes the supply of α-amino groups necessary for the flow of glyoxylate through the main assimilatory pathway during growth on C1 compounds.

Sign in / Sign up

Export Citation Format

Share Document