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 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 Unbiased second-division segregation in Neurospora

1967 ◽  
Vol 10 (3) ◽  
pp. 289-294 ◽  
Author(s):  
Adrian M. Srb ◽  
Howard Jarolmen
Keyword(s):  
Mating Type ◽  
Wild Type ◽  
Different Origin

Results of crosses of a large number of Neurosporas of different origin, including several distinct strains of N. sitophila, were utilized to re-examine the question of whether certain wild-type Neurosporas other than N. crassa show biases in the two types of second-division segregation. Segregations for alleles of the mating type and peak loci on a wide variety of genetic backgrounds gave little evidence for excess either of symmetrical or asymmetrical ‘post-reduction’ asci.

ESCAPE FROM MATING-TYPE INCOMPATIBILITY IN BISEXUAL (A + a) NEUROSPORA HETEROKARYONS

1975 ◽  
Vol 17 (3) ◽  
pp. 441-449 ◽  
Author(s):  
A. M. DeLange ◽  
A. J. F. Griffiths
Keyword(s):  
Mating Type ◽  
Loss Of Function ◽  
Wild Type ◽  
Opposite Mating Type ◽  
Type Locus ◽  
Heterokaryon Incompatibility ◽  
Recessive Mutant ◽  
Type Rate ◽  
Wild Type Rate ◽  
Incompatibility Locus

In Neurospora crassa, strains of opposite mating type generally do not form stable heterokaryons because the mating type locus acts as a heterokaryon incompatibility locus. However, when one A and one a strain, having complementing auxotrophic mutants, are placed together on minimal medium, growth may occur, although the growth is generally slow. In this study, escape from such slow growth to that at a wild type or near-wild type rate was observed. The escaped cultures are stable heterokaryons, mostly having lost the mating type allele function from one component nucleus, so that the nuclear types are heterokaryon compatible. Either A or a mating type can be lost. This loss of function has been attributed to deletion since only one nuclear type could be recovered in all heterokaryons except one, but deletion spanning adjacent loci has been directly demonstrated in a minority of cases. Alternatively when one component strain is tol and the other tol+ (tol being a recessive mutant suppressing the heterokaryon incompatibility associated with mating type), escape may occur by the deletion or mutation of tol+, also resulting in heterokaryon compatibility. An induction mechanism for escape is speculated upon.

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.

Mating-type genes control sexual reproduction, conidial germination and virulence in Cochliobolus lunatus

2021 ◽  
Author(s):  
Kexin Liu ◽  
Jiaqi Jia ◽  
Nan Chen ◽  
Dandan Fu ◽  
Jiaying Sun ◽  
...  
Keyword(s):  
Mating Type ◽  
Pathogenic Fungus ◽  
Germination Rate ◽  
Dry Weight ◽  
Single Copy ◽  
Conidial Germination ◽  
Curvularia Lunata ◽  
Wild Type ◽  
Cochliobolus Lunatus ◽  
Mat Genes

Cochliobolus lunatus (anamorph: Curvularia lunata) is a major pathogenic fungus that causes the Curvularia leaf spot of maize. ClMAT1-1-1 and ClMAT1-2-1, the C. lunatus orthologs of Cochliobolus heterostrophus ChMAT1-1-1 and ChMAT1-2-1, were investigated in the present study to uncover their functions in C. lunatus. Southern blot analysis showed that these mating-type MAT genes exist in the C. lunatus genome as a single copy. ClMAT1-1-1 and ClMAT1-2-1 were knocked out and complemented to generate ΔClmat1-1-1 and ΔClmat1-2-1, ΔClmat1-1-1-C and ΔClmat1-2-1-C, respectively. The mutant strains had defective sexual development and failed to produce pseudothecia. There were no significant differences in growth rate or conidia production between the mutant and wild-type strains. However, the aerial mycelia and mycelial dry weight of ΔClmat1-1-1 and ΔClmat1-2-1 were lower than that of wild type, suggesting that MAT genes affect asexual development. ClMAT genes were involved in the responses to cell wall integrity and osmotic adaptation. ΔClmat1-2-1 had a lower conidial germination rate than the wild-type strain CX-3. The virulence of ΔClmat1-2-1 and ΔClmat1-1-1 was also reduced compared to the wild type. Complementary strains could restore all the phenotypes.

Sporulation mutants in Cochliobolus carbonum

1973 ◽  
Vol 51 (1) ◽  
pp. 207-209 ◽  
Author(s):  
K. J. Leonard
Keyword(s):  
Ultraviolet Irradiation ◽  
Segregation Ratio ◽  
Wild Type ◽  
Cochliobolus Carbonum ◽  
The Third ◽  
Germ Tubes

Three types of mutants were induced in cultures of Cochliobolus carbonum by ultraviolet irradiation. The mutant C1 abc formed abnormally shaped conidia which proliferated in chains rather than being arranged in a spiral on the conidiophore as in wild-type isolates; a second mutant, C2 pcg, produced conidia which germinated precociously while still attached to the conidiophore and which formed secondary conidia at the ends of short germ tubes; and the third, C1 nc1, formed no conidia. A fourth mutant, C1 nc2, which also failed to form conidia was isolated from a culture grown on a medium containing acriflavin. A 1: 1 segregation ratio was obtained in crosses of C1 abc × wild type, but in crossesC2 pcg × wild type and C1 nc1 × wild type nearly all of the progeny were wild type. The mutants C2 pcg and C1 nc1 failed to form perithecia but could serve as male parents; C1 nc2 was completely infertile. Preliminary attempts to determine whether the pcg and nc mutants were controlled cytoplasmically were inconclusive.

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.

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 Developmental mutants in a homothallic strain of Physarum polycephalum

1973 ◽  
Vol 21 (1) ◽  
pp. 79-86 ◽  
Author(s):  
A. E. Wheals
Keyword(s):  
Synergistic Effect ◽  
Ultraviolet Light ◽  
Mating Type ◽  
Physarum Polycephalum ◽  
High Efficiency ◽  
Type A ◽  
Wild Type ◽  
Developmental Transition ◽  
Developmental Mutants

SUMMARYA derivative line of the homothallic Colonia strain of Physarum polycephalum has been isolated which produces plasmodia with high efficiency within clones of amoebae. Using the synergistic effect of ultraviolet light and caffeine, mutants of this line have been isolated which fail to undergo the developmental transition between haploid amoebae and diploid plasmodia (apt mutants). They are isolated by selecting for amoebae which fail to produce plasmodia within clones. Complementation tests of four mutants have shown that they are mutants of four different loci and they are recessive to wild-type. A further analysis of one mutant reveals that the apt-1 locus is unlinked to three other known markers. Crosses of this mutant with heterothallic strains yield progeny which are homothallic indicating that the lesion is not a revertant from a homothallic to a heterothallic mating-type. The use of this system in isolating developmental mutants is discussed.

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.

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