scholarly journals Characterization of the new osmotic mutants (os) which originated during genetic transformation inNeurospora crassa

1977 ◽  
Vol 29 (1) ◽  
pp. 9-19 ◽  
Author(s):  
N. C. Mishra
Keyword(s):  
Linkage Group ◽  
Genetic Transformation ◽  
Neurospora Crassa ◽  
Wild Type ◽  
Induced Mutation ◽  
Group I ◽  
Intragenic Complementation ◽  
Inneurospora Crassa ◽  
New Alleles

SUMMARYInositol independent (inl+) strains were obtained either as transformants following treatment of the inositol requiring (inl) strains ofNeurospora crassawith the wild-type DNA or as revertants without any DNA treatment. A significant number of the inositol-independent transformants were also found to have acquired additional mutations called osmotics (os) which made them unable to grow on 1 m-NaCl medium. None of the inositol-independent revertants were found to possess such osmotic mutations and their growth remained unaffected by the presence of NaCl. Many of the osmotic mutants described here were found to be new alleles of the previously knownos–1mutation on the linkage group I ofNeurospora crassa. The remainder were found to map at two new genetic loci designated asos-6andos-7; these loci were found to be closely linked toos–1. Among the new osmotic mutants onlyos-1andos-6mutants showed intragenic complementation. The mechanism of DNA-induced mutation during transformation is discussed.

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 Characterization of Neurospora crassa cyclic AMP phosphodiesterase activated by calmodulin

1985 ◽  
Vol 232 (2) ◽  
pp. 425-430 ◽  
Author(s):  
M T Téllez-Iñón ◽  
R M Ulloa ◽  
G C Glikin ◽  
H N Torres
Keyword(s):  
Cyclic Amp ◽  
Neurospora Crassa ◽  
Cyclic Nucleotide ◽  
Neuroleptic Drugs ◽  
Wild Type ◽  
Cyclic Amp Phosphodiesterase ◽  
Aerial Hyphae

Activation of cyclic AMP phosphodiesterase I by brain or Neurospora calmodulin was studied. The stimulation required micromolar concentrations of Ca2+, and it was observed at cyclic AMP concentrations between 0.1 and 500 microM. Activation was blocked by EDTA and some neuroleptic drugs such as chlorpromazine and fluphenazine. These drugs inhibit the elongation of N. crassa wild-type aerial hyphae. These results reinforce the evidence towards the recognition of Ca2+-calmodulin as one of the systems controlling cyclic nucleotide concentrations in Neurospora.

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.

DOMINANT-AND-RECESSIVE EPISTASIS IN A HOMEOTIC MOSQUITO MUTANT

1976 ◽  
Vol 18 (4) ◽  
pp. 593-600
Author(s):  
Satish C. Bhalla
Keyword(s):  
Linkage Group ◽  
Wild Type ◽  
Pure Strain ◽  
Group Iii ◽  
Homeotic Mutant ◽  
Culex Pipiens Fatigans ◽  
Group I ◽  
Ratio Data ◽  
Independent Segregation ◽  
Selection For

Folowing selection for 15 generations a pure strain of a homeotic mutant spur was isolated from a Brazilian population of the mosquito Culex pipiens fatigans. Monohybrid crosses showed a 13:3 segregation indicating dominant-and-recessive epistasis for wild-type vs. spur. This implies that a dominant allele at one locus and a recessive at the other interact to produce the mutant phenotype. Dihybrid crosses with linkage group II markers yellow and ruby gave 39:13:9:3 ratios indicating independent segregation. However, the dihybrid cross with linkage group I marker maroon showed a highly significant departure from 39:13:9:3 ratio. Data available indicate that the phenotype spur is controlled by a dominant epistat in linkage group III and a recessive epistat (approximately 31.9 crossover units from maroon) in linkage group I.

scholarly journals REGULATION OF PHOSPHATE METABOLISM IN NEUROSPORA CRASSA. CHARACTERIZATION OF REGULATORY MUTANTS

Genetics ◽  
1973 ◽  
Vol 75 (1) ◽  
pp. 61-73
Author(s):  
John F Lehman ◽  
Mary K Gleason ◽  
Sandra K Ahlgren ◽  
Robert L Metzenberg
Keyword(s):  
Alkaline Phosphatase ◽  
Neurospora Crassa ◽  
Control Systems ◽  
Double Mutant ◽  
Phosphorus Metabolism ◽  
Phosphate Metabolism ◽  
Wild Type Allele ◽  
Wild Type ◽  
High Affinity

ABSTRACT A mutant of Neurospora crassa, called UW-6, differs from wild type in being partially constitutive for synthesis of a species of alkaline phosphatase, and also for a species of phosphate permease that has a high affinity for phosphate at high pH. UW-6 is possibly allelic with a mutant called nuc-2 that was previously isolated by Ishikawa. nuc-2 has the converse phenotype, in that it cannot be derepressed for either of these two activities. UW-6 is co-dominant with its wild-type allele in heterokaryons and in partial diploids. An unlinked mutant, nuc-1, is like nuc-2 in that it fails to make the alkaline phosphatase or the permease referred to above. nuc-1 is epistatic to UW-6 in the double mutant. The control of phosphorus metabolism is discussed, and is compared with some other control systems in filamentous fungi.

scholarly journals NEUROSPORA TREHALASE AND ITS STRUCTURAL GENE

Genetics ◽  
1985 ◽  
Vol 110 (2) ◽  
pp. 217-227
Author(s):  
Christopher White ◽  
Deborah B Lee ◽  
Stephen J Free
Keyword(s):  
Molecular Weight ◽  
Linkage Group ◽  
Structural Gene ◽  
Gene Mutations ◽  
Free Medium ◽  
Wild Type ◽  
Group I ◽  
Normal Wild Type

ABSTRACT We have isolated Neurospora trehalaseless mutants and mapped the trehalase structural gene to linkage group I. The structural gene mutations not only affect thermostability and other characteristics of the enzyme but also affect the production of an inhibitor of the wild-type trehalase. The inhibitor appears to be the mutant trehalase. We suggest that the mutant subunits act as inhibitors by entering into the multimeric forms of the enzyme and altering the ability of the normal wild-type subunits to catalyze the cleavage of trehalose.—Wild type trehalase has been purified to near homogeneity, and its characteristics have been studied. It was purified as a tetramer, with each subunit having a molecular weight of 88,000.—We have studied the regulation of trehalase and found the production of trehalase to be glucose repressible. Cells begin to produce trehalase 60 min after being transferred to glucose-free medium.

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.

Cloning, sequence, and photoregulation of al-1, a carotenoid biosynthetic gene of Neurospora crassa

1990 ◽  
Vol 10 (10) ◽  
pp. 5064-5070
Author(s):  
T J Schmidhauser ◽  
F R Lauter ◽  
V E Russo ◽  
C Yanofsky
Keyword(s):  
Linkage Group ◽  
Neurospora Crassa ◽  
Carotenoid Biosynthesis ◽  
Mrna Levels ◽  
Biosynthetic Gene ◽  
Biosynthetic Enzyme ◽  
Group I ◽  
Phytoene Dehydrogenase ◽  
Initiation Of Transcription ◽  
Residue Polypeptide

Carotenoid biosynthesis is regulated by blue light during growth of Neurospora crassa mycelia. We have cloned the al-1 gene of N. crassa encoding the carotenoid-biosynthetic enzyme phytoene dehydrogenase and present an analysis of its structure and regulation. The gene encodes a 595-residue polypeptide that shows homology to two procaryotic carotenoid dehydrogenases. RNA measurements showed that the level of al-1 mRNA increased over 70-fold in photoinduced mycelia. Transcription run-on studies indicated that the al-1 gene was regulated at the level of initiation of transcription in response to photoinduction. The photoinduced increase of al-1 mRNA levels was not observed in two Neurospora mutants defective in all physiological photoresponses. Analysis of cosmid containing al-1 and of a translocation strain with a breakpoint within al-1 indicated that al-1 transcription proceeds towards the centromere of linkage group I of N. crassa.

scholarly journals Type IV Pili Are Required for Virulence, Twitching Motility, and Biofilm Formation of Acidovorax avenae subsp. citrulli

2009 ◽  
Vol 22 (8) ◽  
pp. 909-920 ◽  
Author(s):  
Ofir Bahar ◽  
Tal Goffer ◽  
Saul Burdman
Keyword(s):  
Biofilm Formation ◽  
Host Plants ◽  
Seed Transmission ◽  
Type Iv Pili ◽  
Twitching Motility ◽  
Wild Type ◽  
Type Iv ◽  
Group I ◽  
Tn5 Mutant

Acidovorax avenae subsp. citrulli is the causal agent of bacterial fruit blotch (BFB), a threatening disease of watermelon, melon, and other cucurbits. Despite the economic importance of BFB, relatively little is known about basic aspects of the pathogen's biology and the molecular basis of its interaction with host plants. To identify A. avenae subsp. citrulli genes associated with pathogenicity, we generated a transposon (Tn5) mutant library on the background of strain M6, a group I strain of A. avenae subsp. citrulli, and screened it for reduced virulence by seed-transmission assays with melon. Here, we report the identification of a Tn5 mutant with reduced virulence that is impaired in pilM, which encodes a protein involved in assembly of type IV pili (TFP). Further characterization of this mutant revealed that A. avenae subsp. citrulli requires TFP for twitching motility and wild-type levels of biofilm formation. Significant reductions in virulence and biofilm formation as well as abolishment of twitching were also observed in insertional mutants affected in other TFP genes. We also provide the first evidence that group I strains of A. avenae subsp. citrulli can colonize and move through host xylem vessels.

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