Effect of temperature and temperature shifts on growth and branching of a wild type and a temperature sensitive colonial mutant (Cot 1) of Neurospora crassa

1977 ◽  
Vol 113 (1-2) ◽  
pp. 43-48 ◽  
Author(s):  
Graham C. Steele ◽  
Anthony P. J. Trinci
Keyword(s):  
Neurospora Crassa ◽  
Effect Of Temperature ◽  
Temperature Sensitive ◽  
Wild Type

scholarly journals Amino acid substitutions in mutant forms of histidinol dehydrogenase from Neurospora crassa

1967 ◽  
Vol 105 (1) ◽  
pp. 39-44 ◽  
Author(s):  
D J Bennett ◽  
E H Creaser
Keyword(s):  
Amino Acid ◽  
Neurospora Crassa ◽  
Temperature Sensitive ◽  
Amino Acid Substitutions ◽  
Wild Type ◽  
Temperature Sensitive Mutants ◽  
Nad Oxidoreductase ◽  
Histidinol Dehydrogenase ◽  
Mutant Forms ◽  
Two Temperature

Amino acid changes in the enzyme l-histidinol dehydrogenase (l-histidinol–NAD oxidoreductase, EC 1.1.1.23) have been determined between the wild-type Neurospora crassa and two temperature-sensitive mutants. Comparison was made between amino acid analyses of peptides of differing electrophoretic and chromatographic mobilities resulting from tryptic and chymotryptic digestion of protein from wild-type and mutant K26, and wild-type and mutant K445 strains, respectively. The analyses demonstrate the substitution of aspartic acid for alanine in mutant K26, and leucine for histidine in mutant K445. The effects of the resulting changes in polarity and charge are discussed in relation to the catalytic functioning of the proteins.

scholarly journals Structural gene for ornithine decarboxylase in Neurospora crassa

1985 ◽  
Vol 5 (6) ◽  
pp. 1301-1306
Author(s):  
P Eversole ◽  
J J DiGangi ◽  
T Menees ◽  
R H Davis
Keyword(s):  
Linkage Group ◽  
Neurospora Crassa ◽  
Ornithine Decarboxylase ◽  
Structural Gene ◽  
Minimal Medium ◽  
Temperature Sensitive ◽  
Wild Type ◽  
Wild Type Enzyme ◽  
Group V

To define the structural gene for ornithine decarboxylase (ODC) in Neurospora crassa, we sought mutants with kinetically altered enzyme. Four mutants, PE4, PE7, PE69, and PE85, were isolated. They were able to grow slowly at 25 degrees C on minimal medium but required putrescine or spermidine supplementation for growth at 35 degrees C. The mutants did not complement with one another or with ODC-less spe-1 mutants isolated in earlier studies. In all of the mutants isolated to date, the mutations map at the spe-1 locus on linkage group V. Strains carrying mutations PE4, PE7, and PE85 displayed a small amount of residual ODC activity in extracts. None of them had a temperature-sensitive enzyme. The enzyme of the PE85 mutant had a 25-fold higher Km for ornithine (5mM) than did the enzyme of wild-type or the PE4 mutant (ca. 0.2 mM). The enzyme of this mutant was more stable to heat than was the wild-type enzyme. These characteristics were normal in the mutant carrying allele PE4. The mutant carrying PE85 was able to grow well at 25 degrees C and weakly at 35 degrees C with ornithine supplementation. This mutant and three ODC-less mutants isolated previously displayed a polypeptide corresponding to ODC in Western immunoblots with antibody raised to purified wild-type ODC. We conclude that spe-1 is the structural gene for the ODC.

scholarly journals TEMPERATURE-SENSITIVE PLEIOTROPIC REVERTANTS FROM A MUTANT IN THE AROM GENE CLUSTER OF NEUROSPORA CRASSA

Genetics ◽  
1974 ◽  
Vol 76 (4) ◽  
pp. 715-721
Author(s):  
Mary E Case ◽  
Norman H Giles
Keyword(s):  
Molecular Weight ◽  
Neurospora Crassa ◽  
Gene Cluster ◽  
Reductase Activity ◽  
Temperature Sensitive ◽  
Missense Mutations ◽  
Wild Type ◽  
Nonsense Mutations ◽  
Biochemical Studies

ABSTRACT Genetical and biochemical studies have been performed with revertants induced in a polyaromatic mutant (No. 58) in the arom gene cluster of Neurospora crassa. In addition to complete and partial revertants able to grow on minimal at both 25° and 35°, temperature-sensitive revertants capable of growth on minimal at 25° but not at 35° have been recovered. One of these revertants has been shown to lack biosynthetic dehydroquinase activity at both temperatures (utilizing the inducible catabolic isozyme for growth at 25°), to have dehydroshikimate reductase activity only at 25°, and to form an arom aggregate having a molecular weight approximately one-half that of wild type. These results are interpreted as indicating that pleiotropic mutants in the arom gene cluster can result from missense mutations, as well as from nonsense mutations as indicated in previous studies.

scholarly journals Isolation and Characterization of a Temperature-Sensitive Circadian Clock Mutant of Neurospora crassa

Genetics ◽  
1997 ◽  
Vol 146 (2) ◽  
pp. 525-530 ◽  
Author(s):  
Louis W Morgan ◽  
Jerry F Feldman
Keyword(s):  
Circadian Clock ◽  
Neurospora Crassa ◽  
Mutant Strain ◽  
Double Mutant ◽  
Period Length ◽  
Temperature Sensitive ◽  
Wild Type ◽  
Isolation And Characterization ◽  
Double Mutant Strain ◽  
Clock Mutant

A new circadian clock mutant has been isolated in Neurospora crassa. This new mutation, called period-6 (pd-6), has two features novel to known clock mutations. First, the mutation is temperature sensitive. At restrictive temperatures (above 21°) the mutation shortens circadian period length from a wild-type value of 21.5 hr to 18 hr. At permissive temperatures (below 21°) the mutant has a 20.5-hr period length close to that of the wild-type strain. Second, the prd-6 mutation is epistatic to the previously isolated clock mutation period-2 (prd-2). This epistasis is unusual in that the prd-2 prd-6 double mutant strain has an 18-hr period length at both the restrictive and permissive temperatures. That is, the temperature-sensitive aspect of the phenotype of the prd-6 strain is lost in the prd-2 prd-6 double mutant strain. This suggests that the gene products of the prd-2 and prd-6 loci may interact physically and that the presence of a normal prd-2+ protein is required for low temperature to “rescue” the prd-6 mutant phenotype. These results, combined with our recent finding that prd-2 and some alleles of the frq gene show genetic synergy, suggest that it may be possible to establish a more comprehensive model of the Neurospora circadian clock.

STUDIES ON BIOSYNTHETIC ENZYMES: I. MUTANT FORMS OF HISTIDINOL DEHYDROGENASE FROM NEUROSPORA CRASSA

1965 ◽  
Vol 43 (7) ◽  
pp. 993-1000 ◽  
Author(s):  
E. H. Creaser ◽  
D. J. Bennett ◽  
R. B. Drysdale
Keyword(s):  
Activation Energy ◽  
Neurospora Crassa ◽  
Kinetic Properties ◽  
Temperature Sensitive ◽  
Wild Type ◽  
Temperature Sensitive Mutants ◽  
Michaelis Constants ◽  
Histidinol Dehydrogenase ◽  
Mutant Forms ◽  
Two Temperature

Data are presented on the kinetic properties of the enzyme histidinol dehydrogenase obtained from the wild type Neurospora crassa and from 15 mutants. Differences were observed in pH curves and in Michaelis constants, both for histidinol and NAD. Ten mutants had modified affinity for NAD and three for histidinol, and one was modified in both these parameters. Two temperature-sensitive mutants were found to have an enzyme with a different activation energy from the normal. The data are discussed in relation to theories about whether histidinol dehydrogenase is a multifunctional enzyme in this organism or is part of an operon system.

scholarly journals Structural gene for ornithine decarboxylase in Neurospora crassa.

1985 ◽  
Vol 5 (6) ◽  
pp. 1301-1306 ◽  
Author(s):  
P Eversole ◽  
J J DiGangi ◽  
T Menees ◽  
R H Davis
Keyword(s):  
Linkage Group ◽  
Neurospora Crassa ◽  
Ornithine Decarboxylase ◽  
Structural Gene ◽  
Minimal Medium ◽  
Temperature Sensitive ◽  
Wild Type ◽  
Wild Type Enzyme ◽  
Group V

To define the structural gene for ornithine decarboxylase (ODC) in Neurospora crassa, we sought mutants with kinetically altered enzyme. Four mutants, PE4, PE7, PE69, and PE85, were isolated. They were able to grow slowly at 25 degrees C on minimal medium but required putrescine or spermidine supplementation for growth at 35 degrees C. The mutants did not complement with one another or with ODC-less spe-1 mutants isolated in earlier studies. In all of the mutants isolated to date, the mutations map at the spe-1 locus on linkage group V. Strains carrying mutations PE4, PE7, and PE85 displayed a small amount of residual ODC activity in extracts. None of them had a temperature-sensitive enzyme. The enzyme of the PE85 mutant had a 25-fold higher Km for ornithine (5mM) than did the enzyme of wild-type or the PE4 mutant (ca. 0.2 mM). The enzyme of this mutant was more stable to heat than was the wild-type enzyme. These characteristics were normal in the mutant carrying allele PE4. The mutant carrying PE85 was able to grow well at 25 degrees C and weakly at 35 degrees C with ornithine supplementation. This mutant and three ODC-less mutants isolated previously displayed a polypeptide corresponding to ODC in Western immunoblots with antibody raised to purified wild-type ODC. We conclude that spe-1 is the structural gene for the ODC.

Ultrastructure and Morphology of the Neurospora Crassa Cell Wall Mutants, Slime And Slime X, Using Tem and Sem

1976 ◽  
Vol 34 ◽  
pp. 54-55
Author(s):  
Karen S. Howard ◽  
H. D. Braymer ◽  
M. D. Socolofsky ◽  
S. A. Milligan
Keyword(s):  
Cell Wall ◽  
Neurospora Crassa ◽  
Wild Type ◽  
Morphological Comparison ◽  
Small Areas ◽  
Solid Media ◽  
Thin Sectioning ◽  
X Cells ◽  
Mutant Cells ◽  
Isolated Cell

The recently isolated cell wall mutant slime X of Neurospora crassa was prepared for ultrastructural and morphological comparison with the cell wall mutant slime. The purpose of this article is to discuss the methods of preparation for TEM and SEM observations, as well as to make a preliminary comparison of the two mutants.TEM: Cells of the slime mutant were prepared for thin sectioning by the method of Bigger, et al. Slime X cells were prepared in the same manner with the following two exceptions: the cells were embedded in 3% agar prior to fixation and the buffered solutions contained 5% sucrose throughout the procedure.SEM: Two methods were used to prepare mutant and wild type Neurospora for the SEM. First, single colonies of mutant cells and small areas of wild type hyphae were cut from solid media and fixed with OSO4 vapors similar to the procedure used by Harris, et al. with one alteration. The cell-containing agar blocks were dehydrated by immersion in 2,2-dimethoxypropane (DMP).

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