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  • 1
    Electronic Resource
    Electronic Resource
    A new senescence-inducing mitochondrial linear plasmid in field-isolated Neurospora crassa strains from India (1991)
    Springer
    Current genetics 19 (1991), S. 129-137 
    Details
    ISSN: 1432-0983
    Keywords: Senescence ; Plasmid ; Neurospora ; Mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Several field-collected strains of Neurospora crassa from the vicinity or Aarey, Bombay, India, are prone to precocious senescence and death. Analysis of one strain, Aarely-1e, demonstrated that the genetic determinants for the predisposition to senescence are maternally inherited. The senescence-prone strains contain a 7-kb, linear, mitochondrial DNA plasmid, maranhar, which is not present in long-lived isolates from the same geographical location. The maranhar plasmid has inverted terminal repeats with protein covalently bound at the 5′ termini. Molecular hybridization experiments have demonstrated no substantial DNA sequence homology between the plasmid and the normal mitochondrial (mtDNA) and nuclear genomes of long-lived strains of N. crassa. Integrated maranhar sequences were detected in the mtDNAs of two cultures derived from Aarey-1e, and mtDNAs with the insertion sequences accumulated during subculturing. Nucleotide sequence analysis of cloned fragments of the two insertion sequences demonstrates that that they are flanked by long inverted repeats of mtDNA. The senescence syndrome of the maranhar strains, and the mode of integration of the plasmid, are reminiscent of those seen in the kalilo strains of N. intermedia. Nonetheless, there is no detectable nucleotide sequence homology between the maranhar and kalilo plasmids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00326294
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  • 2
    Electronic Resource
    Electronic Resource
    Cold-sensitive mutation in Neurospora crassa affecting the production of 17S ribosomal RNA from ribosomal precursor RNA (1981)
    Springer
    Current genetics 4 (1981), S. 1-5 
    Details
    ISSN: 1432-0983
    Keywords: Neurospora crassa ; Ribosomal RNA processing ; Cold sensitive ; Ribosome ; Biosynthesis mutant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The cold-sensitive mutant strain of Neurospora crassa, crib-1 (PJ30201) has a conditional defect in ribosome biosynthesis. At 10 °C this mutant underproduces the small (37S) ribosomal subunit. Experiments were done to study rRNA synthesis in crib-1 after a shift from the permissive (25 °C) to the nonpermissive temperature and vice versa. The results showed that the primary cold-sensitive defect in crib-1 is in the function, rather than the synthesis, of a molecule needed for the production of the 17S rRNA component of the 37S subunit. Pulse-labeling experiments showed that at 10 °C crib-1 synthesizes the 2.4-Mdal pre-rRNA molecule which contains the sequences for the 17S, 5.8S and 25S rRNA species, but that processing of this molecule is defective such that relatively few stable 17S rRNA molecules accumulate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00376778
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  • 3
    Electronic Resource
    Electronic Resource
    Magnification of rRNA gene number in a Neurospora crassa strain with a partial deletion of the nucleolus organizer (1986)
    Springer
    Chromosoma 93 (1986), S. 337-340 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Some progeny from crosses between the Neurospora crassa translocation strain T(IL→ VL)OY321 and normal sequence N. crassa strains are duplication strains with a partial deletion of the nucleolus organizer. Despite the deletion, these progeny are viable and produce a functional nucleolus. Quantification of rRNA gene number in these deletion progeny demonstrated a significant loss of rRNA genes, down to 60% of the parental wild-type level. Initially, all of these reduced nucleolus organizer (RNO) strains demonstrated a reduction in the rate of mycelial elongation in growth tubes. After several vegetative growth cycles some progeny reverted to the normal growth phenotype, and also showed an increase in the number of rRNA genes to approximately that of the wild type.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00327592
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  • 4
    Electronic Resource
    Electronic Resource
    Segregation of heterogeneous rDNA segments during demagnification of a Neurospora crassa strain possessing a double nucleolar organizer (1983)
    Springer
    Current genetics 7 (1983), S. 379-384 
    Details
    ISSN: 1432-0983
    Keywords: rDNA ; Neurospora ; Cistron number regulation ; Demagnification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have produced a duplication strain of Neurospora crassa, DpAR33-PR-6, which contains two cytologically visible nucleoli (a DNO or double nucleolar organizer strain). When freshly generated, this strain has approximately twice the number of rRNA cistrons found in the parental (single nucleolar organizer) strains. After several serial propagations, there is a marked reduction in rRNA cistron number, approximating that of the SNO parental strains. This reduction in rRNA cistrons (“demagnification”) was not achieved by breakdown of the VL→IVL translocation used to generate the duplication, as rDNA from the two parents can be distinguished by the size of the non-transcribed spacer region in the rDNA repeat unit of each strain. rDNA characteristic of both parents is present even after demagnification, in approximately equal amounts, suggesting the rRNA cistrons are lost randomly and non-preferentially from each homologous chromatid. In addition, the steady-state growth rate appears to be affected by rRNA cistron number, decreasing in freshly generated DNO strains relative to the parental strains, and returning to parental levels after demagnification.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00445878
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  • 5
    Electronic Resource
    Electronic Resource
    Organization of the ribosomal ribonucleic acid genes in various wild-type strains and wild-collected strains of Neurospora (1984)
    Springer
    Molecular genetics and genomics 196 (1984), S. 275-282 
    Details
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The organization of the ribosomal DNA (rDNA) repcat unit in the standard wild-type strain of Neurospora crassa, 74-OR23-1A, and in 30 other wild-type strains and wild-collected strains of N. crassa, N. tetrasperma, N. sitophila, N. intermedia, and N. discreta isolated from nature, was investigated by restriction enzyme digestion of genomic DNA, and probing of the Southern-blotted DNA fragments with specific cloned pieces of the rDNA unit from 74-OR23-1A. The size of the rDNA unit in 74-OR23-1A was shown to be 9.20 kilobase pairs (kb) from blotting data, and the average for all strains was 9.11+0.21 kb; standard error=0.038; coefficient of variation (C.V.)=2.34%. These data indicate that the rDNA repeat unit size has been highly conserved among the Neurospora strains investigated. However, while all strains have a conserved HindIII site near the 5′ end of the 25 S rDNA coding sequence, a polymorphism in the number and/or position of HindIII sites in the nontranscribed spacer region was found between strains. The 74-OR23-1A strain has two HindIII sites in the spacer, while others have from 0 to at least 3. This restriction site polymorphism is strain-specific and not species-specific. It was confirmed for some strains by restriction analysis of clones containing most of the rDNA repeat unit. The current restriction map of the 74-OR23-1A rDNA repeat unit is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00328060
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  • 6
    Electronic Resource
    Electronic Resource
    A study of L-glutamine: D-fructose 6-phosphate amidotransferase in certain developmental mutants of Neurospora crassa (1974)
    Springer
    Molecular genetics and genomics 129 (1974), S. 77-86 
    Details
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Wild type and 22 mutant strains of Neurospora crassa were compared for L-glutamine: D-fructose 6-phosphate amidotransferase (GFAT: EC 2.6.1.16) specific activity. The mutant genes map at eleven functionally nonallelic loci, mutations at which result in altered mycelial and ascus morphologies. The enzyme GFAT, which is involved in the synthesis of the important mycelial wall constituent chitin, was investigated as a possible causal factor in determining the altered morphologies. When compared with the wild-type (control) activity, a statistically increased GFAT activity was detected in crude extracts of six mutant strains. Two of these strains carry mutant alleles mapping at the peak locus (peak-2 and clock) and the remaining four carry mutant genes mapping at four other loci. GFAT activity was not significantly different from that of wild type in crude extracts prepared from nine other strains carrying mutant alleles that map at the peak locus, or from seven strains carrying the remaining mutant alleles mapping at other loci. In the two cases tested, including that of peak-2, the activity increase segregated with the mutant morphological phenotype when cultures derived from ascospores of tetrads isolated from crosses of the mutants with wild type were assayed. Further studies with crude extracts showed that, compared with wild type, GFAT activity of peak-2 is higher at all growth times between 12 and 72 hours, and the enzyme is more thermolabile at 35°C. The higher GFAT activity of peak-2 was shown probably not to be due to differential feedback inhibition. The peak locus is almost certainly not a structural gene for the enzyme GFAT, since only two out of the eleven strains carrying mutant alleles at the peak locus that were assayed for GFAT activity showed increased activity compared with that of wild type. For the four nonallelic mutants showing higher GFAT activities than wild type, evidence is still insufficient to determine whether or not the appropriate loci are structural genes for GFAT. The increased GFAT activity where found is consistent with, and possibly contributory to, the altered morphologies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00269267
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  • 7
    Electronic Resource
    Electronic Resource
    Ribosomal genes of Neurospora crassa: Constancy of gene number in the conidial and mycelial phases, and homogeneity in length and restriction enzyme cleavage sites within strains (1983)
    Springer
    Molecular genetics and genomics 192 (1983), S. 285-287 
    Details
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We report the results of experiments which, while not specifically designed to study the possibility of rDNA amplification during different developmental stages in the N. crassa life cycle, clearly indicate a relative constancy in the rDNA content of conidia (asexual spores) and mycelial cells. We also report the results of restriction enzyme studies which indicate that the Neurospora rDNA repeat units are homogenous in length and restriction site pattern within any given Neurospora strain. These results directly contradict the recent report of Dutta et al. (1983), in which the authors concluded that the rDNA of germinating conidia is amplified, relative to mycelia, and that up to 10% of the rDNA units are heterogeneous.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00327680
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  • 8
    Electronic Resource
    Electronic Resource
    Ribosomal DNA inheritance and recombination in Neurospora crassa (1988)
    Springer
    Molecular genetics and genomics 211 (1988), S. 541-544 
    Details
    ISSN: 1617-4623
    Keywords: Neurospora crassa ; Ribosomal DNA ; Meiotic segregation ; Recombination ; Crossing over ; Meiotic recombination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The genetic segregation of ribosomal DNA (rDNA) in Neurospora crassa was analyzed by exploiting restriction fragment length polymorphisms in the nontranscribed spacer (NTS) sequences of nine laboratory wild-type strains and wild-collected strains. In an analysis of random spore progeny from seven crosses, and of ordered tetrads from two of those crosses the rDNA was shown to be inherited in a simple, stable Mendelian fashion, exhibiting an approximately 1:1 ratio of the two parental rDNA types. No meiotic recombinants were detected among the progeny, indicating that non-sister-chromatid crossing over is highly suppressed in the rDNA region. The basis for this suppression of meiotic recombination is not known.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425714
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  • 9
    Electronic Resource
    Electronic Resource
    Growth and macromolecular synthesis phenotypes of a heat-sensitive mutant strain, rip-1, of Neurospora crassa (1985)
    Springer
    Molecular genetics and genomics 200 (1985), S. 247-251 
    Details
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A heat-sensitive mutant of Neurospora crassa, strain 4M(t), was isolated using ultraviolet-light mutagenesis followed by the inositol-less death enrichment technique. The heat-sensitivity is the result of a single gene mutation which maps to the distal end of the right arm of linkage group II. The mutation defines the rip-1 gene locus. Both conidial germination and mycelial extension are inhibited in the mutant at 35°C and above (the nonpermissive temperature) but prolonged incubation at that temperature is not lethal to either cell type. Analysis of the lateral mycelial growth rates of wild type and of the rip-1 mutant at a variety of temperatures between 10 and 40°C indicated that the maximal growth rate occurs at 35°C in the wild type, and at 25°C in the rip-1 strain. The rip-1 mutant grows 239-times slower at 35°C than at 25°C, whereas the wild type grows 1.4-times faster. Temperature shift-up experiments showed that even 3 h at 20°C is not sufficient to allow germination at 37°C, thereby showing that the mutant cannot accumulate enough heat-sensitive product at the permissive temperature to contribute to germination at 37°C. The reciprocal temperature shift-down experiments showed that the molecular events at 37°C may be qualitatively useful for germination after shifting to 20°C. Studies of macromolecular synthesis showed that the biochemical defect in the heat-sensitive strain appears to affect RNA synthesis before protein synthesis, although there were differences in the relative effects depending on the age of the germinating conidia and the inhibition of the two processes was never complete. Messenger RNA synthesis is normal in the mutant at 37°C. Previous work has shown that the rip-1 mutant strain has a conditional defect in the accumulation of 25S rRNA and, hence, in 60S ribosomal subunit production (Loo et al. 1981). There are also indications from those studies that the 60S ribosomal subunit may be functionally impaired at the higher temperature. Thus, the growth and macromolecular synthesis phenotypes may result as a consequence of a conditional, ribosome function defect and leads to the hypothesis that the mutation in the rip-1 strain may be in a gene for a 60S ribosomal subunit component, perhaps a ribosomal protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425431
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  • 10
    Electronic Resource
    Electronic Resource
    Cloning, Sequencing and Expression of a Full-Length cDNA Copy of the M1 Double-Stranded RNA Virus from the Yeast, Saccharomyces cerevisiae (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 13 (1997), S. 829-836 
    Details
    ISSN: 0749-503X
    Keywords: Saccharomyces cerevisiae ; killer yeast ; killer virus ; M1 dsRNA virus ; M1 cDNA clone ; DNA sequence ; killer gene expression ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Strains of the budding yeast, Saccharomyces cerevisiae, may contain one or more cytoplasmic viruses with double-stranded RNA (dsRNA) genomes. The killer phenomenon in yeast, in which one cell secretes a killer toxin that is lethal to another cell, is dependent upon the presence of the L-A and M1 dsRNA viruses. The L-A viral genome encodes proteins for the viral capsid, and for synthesis and encapsidation of single-stranded RNA replication cycle intermediates. The M1 virus depends upon the L-A-encoded proteins for its capsid and for the replication of its killer-toxin-encoding genome. A full-length cDNA clone of an M1 genome has been made from a single dsRNA molecule and shown to encode functional killer and killer-immunity functions. The sequence of the clone indicates minor differences from previously published sequences of parts of the M1 genome and of the complete genome of S14 (an internal deletion derivative of M1) but no unreported amino acid variants and no changes in putative secondary structures of the single-stranded RNA. A 118-nucleotide contiguous segment of the M1 genome has not previously been reported; 92 of those nucleotides comprise a segment of A nucleotides in the AU-rich bubble that follows the toxin-encoding reading frame. The GenBank Accession Number for the sequence is U78817; the locus is SCU78817. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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