Growth and macromolecular synthesis phenotypes of a heat-sensitive mutant strain, rip-1, of Neurospora crassa

1985 ◽  
Vol 200 (2) ◽  
pp. 247-251 ◽  
Author(s):  
Peter J. Russell ◽  
Melanie W. Loo ◽  
Nancy S. Schricker
Keyword(s):  
Neurospora Crassa ◽  
Mutant Strain ◽  
Macromolecular Synthesis ◽  
Sensitive Mutant

scholarly journals Heat-sensitive mutant strain of Neurospora crassa, 4M(t), conditionally defective in 25S ribosomal ribonucleic acid production.

1981 ◽  
Vol 1 (3) ◽  
pp. 199-207 ◽  
Author(s):  
M W Loo ◽  
N S Schricker ◽  
P J Russell
Keyword(s):  
Neurospora Crassa ◽  
Mutant Strain ◽  
Ribosomal Rna ◽  
Ribonucleic Acid ◽  
Ribosomal Subunit ◽  
Macromolecular Synthesis ◽  
Sensitive Mutant ◽  
Ribosomal Subunits ◽  
Sequence Of Events ◽  
Ribosomal Rna Processing

A heat-sensitive mutant strain of Neurospora crassa, 4M(t), was studied in an attempt to define its molecular lesion. The mutant strain is inhibited in conidial germination and mycelial extension at the nonpermissive temperature (37 degrees C). Macromolecular synthesis studies showed that both ribonucleic acid (RNA) and protein syntheses are inhibited when 4-h cultures are shifted from 20 to 37 degrees C. Density gradient analysis of ribosomal subunits made at 37 degrees C indicated that strain 4M(t) is deficient in the accumulation of 60S ribosomal subunits in that the ratio of 60S/37S subunits was 0.29:1 compared with 1.6:1 for the parental strain. This phenotype was shown to be the result of a slow rate of processing of, and a deficiency in the amount of, the immediate precursor to 25S ribosomal RNA (the large RNA of the 60S subunit) in the sequence of events constituting the production of mature ribosomal RNAs from the primary transcript of the ribosomal deoxyribonucleic acid, the precursor ribosomal RNA molecule. Analysis of polysomes suggested that the heat-sensitive gene product might function in both the assembly and the function of the 60S ribosomal subunit, since there was a smaller proportion of newly made 60S subunits synthesized at 37 degrees C in the polysome region of the gradients than in the monosome-plus-subunit region. The ribosomal RNA processing defect is apparently responsible for the observed defects in germination and macromolecular synthesis at 37 degrees C, but the precise molecular lesion is not known. On the basis of these results, the heat-sensitive mutant allele in the 4M(t) strain is considered to define the rip1 (ribosome production) gene locus.

Heat-sensitive mutant strain of Neurospora crassa, 4M(t), conditionally defective in 25S ribosomal ribonucleic acid production

1981 ◽  
Vol 1 (3) ◽  
pp. 199-207
Author(s):  
M W Loo ◽  
N S Schricker ◽  
P J Russell
Keyword(s):  
Neurospora Crassa ◽  
Mutant Strain ◽  
Ribosomal Rna ◽  
Ribonucleic Acid ◽  
Ribosomal Subunit ◽  
Macromolecular Synthesis ◽  
Sensitive Mutant ◽  
Ribosomal Subunits ◽  
Sequence Of Events ◽  
Ribosomal Rna Processing

A heat-sensitive mutant strain of Neurospora crassa, 4M(t), was studied in an attempt to define its molecular lesion. The mutant strain is inhibited in conidial germination and mycelial extension at the nonpermissive temperature (37 degrees C). Macromolecular synthesis studies showed that both ribonucleic acid (RNA) and protein syntheses are inhibited when 4-h cultures are shifted from 20 to 37 degrees C. Density gradient analysis of ribosomal subunits made at 37 degrees C indicated that strain 4M(t) is deficient in the accumulation of 60S ribosomal subunits in that the ratio of 60S/37S subunits was 0.29:1 compared with 1.6:1 for the parental strain. This phenotype was shown to be the result of a slow rate of processing of, and a deficiency in the amount of, the immediate precursor to 25S ribosomal RNA (the large RNA of the 60S subunit) in the sequence of events constituting the production of mature ribosomal RNAs from the primary transcript of the ribosomal deoxyribonucleic acid, the precursor ribosomal RNA molecule. Analysis of polysomes suggested that the heat-sensitive gene product might function in both the assembly and the function of the 60S ribosomal subunit, since there was a smaller proportion of newly made 60S subunits synthesized at 37 degrees C in the polysome region of the gradients than in the monosome-plus-subunit region. The ribosomal RNA processing defect is apparently responsible for the observed defects in germination and macromolecular synthesis at 37 degrees C, but the precise molecular lesion is not known. On the basis of these results, the heat-sensitive mutant allele in the 4M(t) strain is considered to define the rip1 (ribosome production) gene locus.

scholarly journals Epistatic and Synergistic Interactions Between Circadian Clock Mutations in Neurospora crassa

Genetics ◽  
2001 ◽  
Vol 159 (2) ◽  
pp. 537-543
Author(s):  
Louis W Morgan ◽  
Jerry F Feldman
Keyword(s):  
Circadian Clock ◽  
Neurospora Crassa ◽  
Mutant Strain ◽  
Temperature Compensation ◽  
Double Mutant ◽  
Synergistic Interactions ◽  
Long Period ◽  
Double Mutant Strain ◽  
Short Period ◽  
Compensation Mechanisms

Abstract We identified a series of epistatic and synergistic interactions among the circadian clock mutations of Neurospora crassa that indicate possible physical interactions among the various clock components encoded by these genes. The period-6 (prd-6) mutation, a short-period temperature-sensitive clock mutation, is epistatic to both the prd-2 and prd-3 mutations. The prd-2 and prd-3 long-period mutations show a synergistic interaction in that the period length of the double mutant strain is considerably longer than predicted. In addition, the prd-2 prd-3 double mutant strain also exhibits overcompensation to changes in ambient temperature, suggesting a role in the temperature compensation machinery of the clock. The prd-2, prd-3, and prd-6 mutations also show significant interactions with the frq7 long-period mutation. These results suggest that the gene products of prd-2, prd-3, and prd-6 play an important role in both the timing and temperature compensation mechanisms of the circadian clock and may interact with the FRQ protein.

scholarly journals One-carbon metabolism in Neurospora crassa wild-type and in mutants partially deficient in serine hydroxymethyltransferase

1976 ◽  
Vol 160 (2) ◽  
pp. 305-314 ◽  
Author(s):  
E A Cossins ◽  
P Y Chan ◽  
G Combepine
Keyword(s):  
Neurospora Crassa ◽  
Mutant Strain ◽  
Methylenetetrahydrofolate Reductase ◽  
Serine Hydroxymethyltransferase ◽  
Growth Media ◽  
Wild Type ◽  
Feeding Experiments ◽  
Methylenetetrahydrofolate Dehydrogenase ◽  
In The Wild ◽  
One Carbon Metabolism

1. The concentrations of folate-dependent enzymes in Neurospora crassa Lindegren A wild type (FGSC no. 853), Ser-l mutant, strain H605a (FGSC no. 118), and for mutant, strain C-24 (FGSC no. 9), were compared during exponential growth on defined minimal media. Both mutants were partially lacking in serine hydroxymethyltransferase, but contained higher concentrations of 10-formyltetrahydrofolate synthetase than did the wild type. Mycelia of the mutants contained higher concentrations of these enzymes when growth media were supplemented with 1mM-glycine. In the wild-type, this glycine supplement also increased the specific activities of 5,10-methylenetetrahydrofolate dehydrogenase and 5,10-methylenetetrahydrofolate reductase. 5. During growth, total folate and polyglutamyl folate concentrations were greatest in the wild-type. Methylfolates were not detected in mutant Ser-l, and were only present in the for mutant after growth in glycine-supplemented media. Exogenous glycine increased folate concentration threefold in the wild type, mainly owing to increases in unsubstituted polyglutamyl derivatives. 3. Feeding experiments using 14C-labelled substrates showed that C1 units were generated from formate, glycine and serine in the wild type. Greater incorporation of 14C occurred when mycelia were cultured in glycine-supplemented media. Formate and serine were precursors of C1 units in the mutants, but the ability to cleave glycine was slight or lacking.

Phytoene photoinduction in a carotenoid mutant of Neurospora crassa

1976 ◽  
Vol 54 (21) ◽  
pp. 2445-2448 ◽  
Author(s):  
J. C. Lansbergen ◽  
R. L. Renaud ◽  
R. E. Subden
Keyword(s):  
Neurospora Crassa ◽  
Mutant Strain ◽  
Biosynthetic Pathway ◽  
Dry Weight ◽  
Carotenoid Content ◽  
Second Step ◽  
Light Induction ◽  
Wild Type

The dynamics of carotenoid photoinduction in N. crassa have been studied by comparing a wild type and a mutant strain lacking the second step (phytoene dehydrogenation) in the carotene biosynthetic pathway. The data indicate that dark-grown cultures contain 113 to 150 μg carotenoid per gram dry weight and that light induction can double the carotenoid content. Phytoene synthesis and phytoene dehydrogenations are photoregulated independently.

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