scholarly journals A RECESSIVE CIRCADIAN CLOCK MUTATION AT THE frq LOCUS OF NEUROSPORA CRASSA

Genetics ◽  
1986 ◽  
Vol 114 (4) ◽  
pp. 1095-1110
Author(s):  
Jennifer J Loros ◽  
Adam Richman ◽  
Jerry F Feldman
Keyword(s):  
Circadian Clock ◽  
Neurospora Crassa ◽  
Temperature Compensation ◽  
Single Gene ◽  
Complete Loss ◽  
The Other ◽  
Compensation Mechanism ◽  
Wild Type ◽  
Structure Mapping ◽  
Clock Mutant

ABSTRACT A circadian clock mutant of Neurospora crassa, the most distinctive characteristic of which is the complete loss of temperature compensation of its period length, maps to the frq locus where seven other clock mutants have previously been mapped. This mutant, designated frq-9, is recessive to the wild-type allele and to each of the other frq mutants; thus, it differs from the other mutants, which show incomplete dominance to wild type and to each other. Complementation analysis suggests either that the frq locus is a single gene or that frq-9 is a deletion that overlaps adjacent genes. Preliminary efforts at fine structure mapping have indicated that recombination between certain pairs of frq mutations is less than 0.005%, a distance consistent with the locus being a single gene. The recessive nature of frq-9, coupled with complete loss of temperature compensation, suggests that this mutant may represent the null phenotype of the locus and that the frq gene is involved in the temperature compensation mechanism of the clock.—Genetic mapping studies have placed the frq locus on linkage group VIIR, midway between oli (oligomycin resistance) and for (formate auxotrophy), about 2 map units from each, and clearly indicate that frq and oli are separate genes.

scholarly journals GENETIC AND PHYSIOLOGICAL CHARACTERISTICS OF A SLOW-GROWING CIRCADIAN CLOCK MUTANT OF NEUROSPORA CRASSA

Genetics ◽  
1978 ◽  
Vol 88 (2) ◽  
pp. 255-265
Author(s):  
Jerry F Feldman ◽  
Cheryl A Atkinson
Keyword(s):  
Linkage Group ◽  
Circadian Clock ◽  
Neurospora Crassa ◽  
Double Mutant ◽  
Slow Growth ◽  
Period Length ◽  
The Other ◽  
Wild Type ◽  
Long Period ◽  
Clock Mutant

ABSTRACT A circadian clock mutant of Neurospora crassa with a period length of about 25.8 hours (4 hr longer than wild type) has been isolated after mutagenesis of the band strain. This mutant, called frq-5, segregates as a single nuclear gene, maps near the centromere on linkage group III, and is unlinked to four previously described clock mutants clustered on linkage group VII R (Feldman and Hoyle 1973, 1976). frq-5 differs from the other clock mutants in at least two other respects: (1) it is recessive in heterokaryons, and (2) it grows at about 60% the rate of the parent band strain on both minimal and complete media. Double mutants between frq-5 and each of the other clock mutants show additivity of period length-two long period mutants produce a double mutant whose period length is longer than either of the two single mutants, while a long and a short period double mutant has an intermediate period length. Although slow growth and long periodicity of frq-5 have segregated together among more than 300 progeny, slow growth per se is not responsible for the long period, since all the double mutants have the slow growth characteristic of frq-5, but have period lengths both shorter and longer than wild type.

scholarly journals THE frq LOCUS IN NEUROSPORA CRASSA: A KEY ELEMENT IN CIRCADIAN CLOCK ORGANIZATION

Genetics ◽  
1980 ◽  
Vol 96 (4) ◽  
pp. 877-886 ◽  
Author(s):  
George F Gardner ◽  
Jerry F Feldman
Keyword(s):  
Linkage Group ◽  
Circadian Clock ◽  
Neurospora Crassa ◽  
Single Gene ◽  
Gene Interaction ◽  
Period Length ◽  
Additive Effects ◽  
Wild Type ◽  
Incomplete Dominance ◽  
Significant Gene

ABSTRACT Four new circadian clock mutants of Neurospora crassa have been isolated that alter the period length of the circadian conidiation rhythm. Three of these are at the frq locus on linkage group VIIR, where four other clock mutants are located. In contrast to wild type, which has a period length of 21.6 hr, frq-6 has a period length of 19 hr, while frq-7 and frq-8 have period lengths of 29 hr and represent the largest effects of any single gene mutants on circadian periodicity. Thus, seven mutants have now been isolated that map to the frq locus, with period lengths ranging from 16.5 to 29 hr, and each mutant alters clock periodicity by an integral multiple of 2.5 hr. In addition, all frq mutants show incomplete dominance in heterokaryons. The large percentage of clock mutants that map to this locus, coupled with their unique properties, suggests that the frq locus plays an important role in clock organization.—The fourth mutant, designated chrono (chr), has a period length of 23.5 hr, shows incomplete dominance and is unlinked to either of the previously identified clock loci, frq or prd (formerly called frq-5). Double mutants between various combinations of clock mutants show additive effects and indicate no significant gene interaction among mutants at these three loci.

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.

scholarly journals DIRECT INDUCTION IN WILD-TYPE NEUROSPORA CRASSA OF MUTANTS (qa-1C) CONSTITUTIVE FOR THE CATABOLISM OF QUINATE AND SHIKIMATE

Genetics ◽  
1972 ◽  
Vol 72 (3) ◽  
pp. 411-417
Author(s):  
C W H Partridge ◽  
Mary E Case ◽  
Norman H Giles
Keyword(s):  
Neurospora Crassa ◽  
Single Gene ◽  
Ultra Violet ◽  
Wild Type ◽  
Color Test ◽  
Catabolic Enzymes ◽  
Direct Induction

ABSTRACT A color test has been developed for the selection and identification of mutants in Neurospora crassa, constitutive for the three normally inducible enzymes which convert quinate to protocatechuate. By this means seven such mutants have been recovered after ultra violet irradiation of wild type and have been shown to be allelic (or very closely linked) to the qa-1C mutants previously obtained by other means. Thus, the regulation of the synthesis of these three catabolic enzymes is indicated to be under the control of a single gene, qa-1+.

scholarly journals COMPLEMENTATION ANALYSIS OF LINKED CIRCADIAN CLOCK MUTANTS OF NEUROSPORA CRASSA

Genetics ◽  
1976 ◽  
Vol 82 (1) ◽  
pp. 9-17 ◽  
Author(s):  
Jerry F Feldman ◽  
Marian N Hoyle
Keyword(s):  
Linkage Group ◽  
Circadian Clock ◽  
Neurospora Crassa ◽  
Period Length ◽  
Complementation Analysis ◽  
Wild Type ◽  
The Right

ABSTRACT A fourth mutant of Neurospora crassa, designated frq-4, has been isolated in which the period length of the circadian conidiation rhythm is shortened to 19.3 ± 0.3 hours. This mutant is tightly linked to the three previously isolated frq mutants, and all four map to the right arm of linkage group VII about 10 map units from the centromere. Complementation tests suggest, but do not prove, that all four mutations are allelic, since each of the four mutants is co-dominant with the frq  + allele—i.e., heterokaryons have period lengths intermediate between the mutant and wild-type—and since heterokaryons between pairs of mutants also have period lengths intermediate between those of the two mutants.

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.

Isolation of telomere DNA from Neurospora crassa

1987 ◽  
Vol 7 (9) ◽  
pp. 3168-3177
Author(s):  
M G Schechtman
Keyword(s):  
Linkage Group ◽  
Neurospora Crassa ◽  
Genetic Background ◽  
Type Strain ◽  
Wild Type Strain ◽  
The Other ◽  
Wild Type ◽  
Oak Ridge ◽  
Entire Chromosome ◽  
Different Genetic Background

The most distal known gene on Neurospora crassa linkage group VR, his-6, was cloned. A genomic walk resulted in isolation of the telomere at VR. It was obtained from a library in which the endmost nucleotides of the chromosome had not been removed by nuclease treatment before being cloned, and mapping indicates that the entire chromosome end has probably been cloned. Sequences homologous to the terminal 2.5 kilobases of DNA from VR from these Oak Ridge N. crassa strains are found at other sites in the genome. To characterize these sites, I crossed an Oak Ridge-derived his-6 strain with a wild-type strain of different genetic background (Mauriceville) and characterized the hybridization patterns seen in the progeny. It appears that the sequences homologous to the VR terminus are found at genetically different sites in the two parental strains, and no hybridization to the VR telomere from Mauriceville was detected. The other genomic copies identified in the Oak Ridge parent were not telomeres. I suggest that any repeating sequence blocks found immediately adjacent to the VR terminus in Oak Ridge strains must be small and that the repeating element identified in that background may be an N. crassa transposable element integrated near the the chromosome end at VR.

scholarly journals Immunological identification of the alternative oxidase of Neurospora crassa mitochondria.

1989 ◽  
Vol 9 (3) ◽  
pp. 1362-1364 ◽  
Author(s):  
A M Lambowitz ◽  
J R Sabourin ◽  
H Bertrand ◽  
R Nickels ◽  
L McIntosh
Keyword(s):  
Neurospora Crassa ◽  
Oxidase Activity ◽  
Hydroxamic Acid ◽  
Alternative Oxidase ◽  
Fungal Species ◽  
The Other ◽  
Wild Type ◽  
Higher Plant ◽  
Sauromatum Guttatum ◽  
Immunological Identification

Neurospora crassa mitochondria use a branched electron transport system in which one branch is a conventional cytochrome system and the other is an alternative cyanide-resistant, hydroxamic acid-sensitive oxidase that is induced when the cytochrome system is impaired. We used a monoclonal antibody to the alternative oxidase of the higher plant Sauromatum guttatum to identify a similar set of related polypeptides (Mr, 36,500 and 37,000) that was associated with the alternative oxidase activity of N. crassa mitochondria. These polypeptides were not present constitutively in the mitochondria of a wild-type N. crassa strain, but were produced in high amounts under conditions that induced alternative oxidase activity. Under the same conditions, mutants in the aod-1 gene, with one exception, produced apparently inactive alternative oxidase polypeptides, whereas mutants in the aod-2 gene failed to produce these polypeptides. The latter findings support the hypothesis that aod-1 is a structural gene for the alternative oxidase and that the aod-2 gene encodes a component that is required for induction of alternative oxidase activity. Finally, our results indicate that the alternative oxidase is highly conserved, even between plant and fungal species.

scholarly journals Mutation of the cys-9 Gene, Which Encodes Thioredoxin Reductase, Affects the Circadian Conidiation Rhythm in Neurospora crassa

Genetics ◽  
1997 ◽  
Vol 146 (1) ◽  
pp. 101-110 ◽  
Author(s):  
Kiyoshi Onai ◽  
Hideaki Nakashima
Keyword(s):  
Neurospora Crassa ◽  
Type Strain ◽  
Temperature Compensation ◽  
Wild Type Strain ◽  
Thioredoxin Reductase ◽  
Period Length ◽  
Phase Shifting ◽  
Wild Type ◽  
Partial Loss ◽  
Continuous Darkness

Ten cysteine auxotrophs of Neurospora crassa were examined with regard to the period lengths of their circadian conidiation rhythms. One of the these cysteine auxotrophs, cys-9, showed dramatic changes in the circadian conidiation rhythm. At 10 μm methionine, the cys-9 mutant had a period length that was 5 hr shorter than that of the wild-type strain during the first 3 days after transfer to continuous darkness. At this concentration of methionine, the period length was unstable after the fourth day and varied widely from 11 to 31 hr. In contrast, other cysteine auxotrophs did not show such instability of the period length at any of the concentrations of methionine tested. Furthermore, only the cys-9 mutant exhibited partial loss of the capacity for temperature compensation of the period length. With regard to cold-induced phase-shifting of the circadian conidiation rhythm, the cys-9 mutant was more sensitive than the wild-type strain to low temperature. The cys-9  + gene was cloned and was found to encode NADPH-dependent thioredoxin reductase. These results indicate that mutation of the gene for thioredoxin reductase results in abnormal expression of the circadian conidiation rhythm in N. crassa.

Clockmutation facilitates accumulation of cholesterol in the liver of mice fed a cholesterol and/or cholic acid diet

2008 ◽  
Vol 294 (1) ◽  
pp. E120-E130 ◽  
Author(s):  
Takashi Kudo ◽  
Mihoko Kawashima ◽  
Toru Tamagawa ◽  
Shigenobu Shibata
Keyword(s):  
Gene Expression ◽  
Circadian Clock ◽  
Cholic Acid ◽  
Mouse Liver ◽  
Clock Genes ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Mutant Mice ◽  
Wild Type ◽  
Clock Mutant

Cholesterol (CH) homeostasis in the liver is regulated by enzymes of CH synthesis such as 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) and catabolic enzymes such as cytochrome P-450, family 7, subfamily A, and polypeptide 1 (CYP7A1). Since a circadian clock controls the gene expression of these enzymes, these genes exhibit circadian rhythm in the liver. In this study, we examined the relationship between a diet containing CH and/or cholic acid (CA) and the circadian regulation of Hmgcr, low-density lipoprotein receptor ( Ldlr), and Cyp7a1 gene expression in the mouse liver. A 4-wk CA diet lowered and eventually abolished the circadian expression of these genes. Not only clock genes such as period homolog 2 (Drosophila) ( Per2) and brain and muscle arnt-like protein-1 ( Bmal1) but also clock-controlled genes such as Hmgcr, Ldlr, and Cyp7a1 showed a reduced and arrhythmic expression pattern in the liver of Clock mutant mice. The reduced gene expression of Cyp7a1 in mice fed a diet containing CA or CH + CA was remarkable in the liver of Clock mutants compared with wild-type mice, and high liver CH accumulation was apparent in Clock mutant mice. In contrast, a CH diet without CA only elevated Cyp7a1 expression in both wild-type and Clock mutant mice. The present findings indicate that normal circadian clock function is important for the regulation of CH homeostasis in the mouse liver, especially in conjunction with a diet containing high CH and CA.

Sign in / Sign up

Export Citation Format

Share Document