COLONY MUTANTS OF COMPATIBLE NOCARDIAE DISPLAYING VARIATIONS IN RECOMBINING CAPACITY

Genetics ◽  
1972 ◽  
Vol 70 (3) ◽  
pp. 341-351
Author(s):  
George H Brownell ◽  
Richard S Walsh
Keyword(s):  
Uv Irradiation ◽  
Mating Type ◽  
Genome Recombination ◽  
X Irradiation ◽  
Increased Sensitivity ◽  
Colonial Morphology ◽  
Rec Genes

ABSTRACT Colonial morphology mutants of Nocardia erythropolis were isolated following ultraviolet (UV) irradiation. The alleles rou-1/smo-1 were located by recombinant analysis and found to be linked to previously mapped characters. On the basis of recombinant class type patterns obtained from various selective characters it was postulated that the rou-1 allele may span a region of unique nucleotides in the Mat-Ce genome. Recombination frequencies of rou-1 and smo-2 bearing mutants of the Mat-Ce mating type were found to differ by over 1000 fold. Attempts to demonstrate that low recombination frequencies produced by the Smo mutants were due to Rec- genes were unsuccessful. No increased sensitivity to either UV or X irradiation was observed by the Smo mutants. Acriflavine treatment of either Rou or Smo colony mutants failed to accelerate reversion or to alter the recombining potentials of the mutants.

Cockayne Syndrome: A Cellular Sensitivity to Ultraviolet Light

PEDIATRICS ◽  
1977 ◽  
Vol 60 (2) ◽  
pp. 135-139
Author(s):  
R. D. Schmickel ◽  
E. H. Y. Chu ◽  
J. E. Trosko ◽  
C. C. Chang
Keyword(s):  
Ultraviolet Light ◽  
Uv Light ◽  
Cockayne Syndrome ◽  
Fibroblast Cultures ◽  
Cellular Sensitivity ◽  
X Irradiation ◽  
Increased Sensitivity ◽  
Cellular Dna ◽  
Thymidine Dimer ◽  
Enzymatic Defect

Two unrelated children, a boy 2½ years old and a girl 4 years old, were affected with the cachectic dwarfism of Cockayne syndrome. Fibroblast cultures derived from these patients exhibited increased sensitivity to ultraviolet (UV) light, but not to x-irradiation, as measured by colony-forming ability. In both Cockayne fibroblast cultures, the rate of removal of thymidine dimer from the irradiated cellular DNA was normal. This demonstration of a cellular defect in Cockayne cells suggests that there may be an enzymatic defect in the repair of UV light-induced damage.

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 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 Increased Sensitivity of DMD Lymphoblastoid Cell To Low Doses of X-Irradiation

1994 ◽  
Vol 12 (2) ◽  
pp. 99-107
Author(s):  
L. Melchiorri ◽  
S. Carturan ◽  
D. Ferrari ◽  
F. Di Virgilio ◽  
O. R. Baricordi
Keyword(s):  
Cellular Membrane ◽  
Peripheral Blood Lymphocytes ◽  
Lymphoid Cells ◽  
Cellular Phenotype ◽  
Ca Uptake ◽  
Small Doses ◽  
X Irradiation ◽  
Increased Sensitivity ◽  
Cell Cycle Length ◽  
Membrane Defect

Several cell membrane abnormalities affecting various cell populations have been reported in Duchenne muscular dystrophy (DMD) by different investigators. In peripheral blood lymphocytes intrinsic cellular membrane defect evidentiated by impairment of capping capacities has been repeatedly obtained, suggesting that DMD product could act in such cellular phenotype at the cytoskeletal compartment. It has been previously reported that lymphoid cells are characterized by high radiosensitivity. On the assumption that DMD phenotypes could increase this susceptibility, we have compared the radiosensitivity of normal and DMD lymphoblastoid cell lines (LCLs) to small doses (0-2Gy) of x-irradiation. The results obtained suggest an increased sensitivity of DMD cells without Ca++ uptake or apoptotic phenomena, associated with an effect upon cell cycle length.

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.

scholarly journals H-NS Regulates DNA Repair inShigella

1998 ◽  
Vol 180 (19) ◽  
pp. 5260-5262 ◽  
Author(s):  
Sunil Palchaudhuri ◽  
Brandon Tominna ◽  
Myron A. Leon
Keyword(s):  
Dna Repair ◽  
Uv Irradiation ◽  
Shigella Flexneri ◽  
Virulence Gene ◽  
High Rate ◽  
High Survival ◽  
Virulence Gene Expression ◽  
E Coli ◽  
X Irradiation ◽  
K 12

ABSTRACT We report a new role for H-NS in Shigella spp.: suppression of repair of DNA damage after UV irradiation. H-NS-mediated suppression of virulence gene expression is thermoregulated inShigella, being functional at 30°C and nonfunctional at 37 to 40°C. We find that H-NS-mediated suppression of DNA repair after UV irradiation is also thermoregulated. Thus, Shigella flexneri M90T, incubated at 37 or 40°C postirradiation, shows up to 30-fold higher survival than when incubated at 30°C postirradiation. The hns mutants BS189 and BS208, both of which lack functional H-NS, show a high rate of survival (no repression) whether incubated at 30 or 40°C postirradiation. Suppression of DNA repair by H-NS is not mediated through genes on the invasion plasmid of S. flexneri M90T, since BS176, cured of plasmid, behaves identically to the parental M90T. Thus, inShigella the nonfunctionality of H-NS permits enhanced DNA repair at temperatures encountered in the human host. However, pathogenic Escherichia coli strains (enteroinvasive and enterohemorrhagic E. coli) show low survival whether incubated at 30 or 40°C postirradiation. E. coli K-12 shows markedly different behavior; high survival postirradiation at both 30 and 40°C. These K-12 strains were originally selected fromE. coli organisms subjected to both UV and X irradiation. Therefore, our data suggest that repair processes, extensively described for laboratory strains of E. coli, require experimental verification in pathogenic strains which were not adapted to irradiation.

NULL MUTANTS OF THE A AND a MATING TYPE ALLELES OF NEUROSPORA CRASSA

1982 ◽  
Vol 24 (2) ◽  
pp. 167-176 ◽  
Author(s):  
A. J. F. Griffiths
Keyword(s):  
Linkage Group ◽  
Neurospora Crassa ◽  
Uv Irradiation ◽  
Mating Type ◽  
Opposite Mating Type ◽  
Extended Study ◽  
Fundamental Properties ◽  
Group I ◽  
Sexual Compatibility ◽  
Null Mutants

Thirty-five null mutants have now been obtained of the A mating type allele, which have simultaneously lost both known functions-heterokaryon incompatibility and sexual compatibility with strains of the opposite mating type, a. The mutants, designated Am, were obtained by selecting for heterokaryon compatibility following UV-irradiation of the normal A. Twenty-five of the mutations were viable as homokaryons. Both functions reverted together when two of these were irradiated. In most respects, Am mutations resemble the previously reported am mutations in their behavior. The Am mutations differ, however, in failing to produce illegitimate empty perithecia in crosses with testers of the same mating type from which they originated. — The previously obtained am mutants were characterized further. It was confirmed that these am mutants show abortive mating reactions, legitimate and illegitimate, with several tester strains, thus showing that such reactions are fundamental properties of the mutants themselves. In support of this, it was shown that the A-like behavior of am strains in the illegitimate reaction is not due to acquisition of determining elements through cytoplasmic contact with A in heterokaryons. It is possible that the sterile am mutants can be carried through a cross by a fertile heterokaryotic partner, but an extended study of meiotic products presumed to stem from this process confirmed that if such a process occurs it can involve no recombination on linkage group I. The single fertile am mutant was shown to have normal recombination on L.G.I. Escape from (A + a) incompatibility was shown to be possible in the identical heterokaryon used for am induction. Escape cannot be ruled out as a source of nonrecoverable am mutations.

Sympathetic Hyperfunction Causes Increased Sensitivity of the Autonomic Nervous System to Whole-Body X Irradiation

2005 ◽  
Vol 163 (2) ◽  
pp. 137-143 ◽  
Author(s):  
Mutsumi Matsuu ◽  
Kazuko Shichijo ◽  
Yuji Ikeda ◽  
Masahiro Ito ◽  
Shinji Naito ◽  
...  
Keyword(s):  
Nervous System ◽  
Autonomic Nervous System ◽  
Whole Body ◽  
Autonomic Nervous ◽  
X Irradiation ◽  
Increased Sensitivity
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