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  • 1
    Electronic Resource
    Electronic Resource
    Helper strains for shortening the dormancy in Phycomyces blakesleeanus (1985)
    Springer
    Current genetics 9 (1985), S. 369-372 
    Details
    ISSN: 1432-0983
    Keywords: Phycomyces ; Isogenic strains ; Quantitative complementation ; Dormancy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Phycomyces blakesleeanus wild-type NRRL-1555(−), the standard strain, when crossed with UBC21(+), another wild-type, gives zygospores that germinate in about 50 days; this is the shortest dormancy period found in Phycomyces. Analyses of crosses with these strains are difficult because of the irregularities occurring in the meiotic segregation of genotypes. Recently, a (+) strain, A56, which is almost isogenic with NRRL1555, has been isolated (Alvarez and Eslava 1983). Zygospores from the cross between the isogenic strains showed a regular pattern of meiotic segregation though dormancy increased almost two-fold. To combine the advantages of isogenicity with shortest dormancies, we have made crosses using heterokaryons carrying nuclei of UBC21 and A56 as (+) parent strains; the (−) parent was always NRRL1555. Under these conditions the zygospores showed early germination, and the number of germinated zygospores containing germspores whose nuclei only originate from meiosis of the diploid nucleus A56/NRRL1555, depended exclusively on the proportion of A56 nuclei present in the heterokaryotic (+) parental strain. With this method the possibilities of genetic analysis in Phycomyces are extended.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00421607
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  • 2
    Electronic Resource
    Electronic Resource
    Molecular characterization of a fungal secondary metabolism promoter: transcription of the Aspergillus nidulans isopenicillin N synthetase gene is modulated by upstream negative elements (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 9 (1993), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The Aspergillus nidulans IPNS gene, encoding isopenicillin N synthetase, is a secondary metabolism gene. It is contiguous to, but divergently transcribed from, the ACVS gene at the penicillin gene cluster. The untranslated region between both ORFs is 872bp long. Here we present the physical and functional characterization of the IPNS transcriptional unit. Transcriptional start point (tsp) mapping reveals heterogeneity at the 5′-end of the mRNA, with a major start at −106 relative to the initiation codon. This indicates that the actual length of the non-transcribed intergenic region is 525bp. Functional elements in the IPNS upstream region have been defined by assaying β-galactosidase activity in extracts from recombinant strains carrying deletion derivatives of the IPNS promoter fused to lacZ, integrated in single copy at the argB locus. Strains were grown in penicillin production broth under carbon catabolite repressing or derepressing conditions. The results of deletion analysis indicate that: (i) the IPNS promoter is mostly regulated by negative controls that act upon a high basal activity; (ii) sequential deletion of three of the negative cis-acting elements results in a mutated promoter that is 40 times (sucrose broth) or 12 times (lactose broth) more active than the wild type; (iii) one of these negative cis-acting elements is involved in sucrose repression. Strikingly, it is located outside the non-transcribed 525 bp intergenic region and maps to the coding region of the divergently transcribed ACVS gene; (iv) a 5′-del-etion up to −56 (relative to the major tsp) contains information to provide almost half of the maximal promoter activity and allows initiation of transcription at the correct site. By using total-protein extracts from mycelia grown under penicillin producing conditions we have detected a DNA-binding activity that specifically shifts a promoter fragment located between −654 and −455(relative to IPNS tsp). Deletions covering this region partially abolish IPNS promoter activity. The fragment in question overlaps the ACVS tsp.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1993.tb01746.x
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  • 3
    Electronic Resource
    Electronic Resource
    Carbon catabolite repression of the Aspergillus nidulans xlnA gene (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 31 (1999), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Expression of the Aspergillus nidulans 22 kDa endoxylanase gene, xlnA, is controlled by at least three mechanisms: specific induction by xylan or xylose; carbon catabolite repression (CCR); and regulation by ambient pH. Deletion analysis of xlnA upstream sequences has identified two positively acting regions: one that mediates specific induction by xylose; and another that mediates the influence of ambient pH and contains two PacC consensus binding sites. The extreme derepressed mutation creAd30 results in considerable, although not total, loss of xlnA glucose repressibility, indicating a major role for CreA in its CCR. Three consensus CreA binding sites are present upstream of the structural gene. Point mutational analysis using reporter constructs has identified a single site, xlnA.C1, that is responsible for direct CreA repression in vivo. Using the creAd30 derepressed mutant background, our results indicate the existence of indirect repression by CreA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01157.x
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  • 4
    Electronic Resource
    Electronic Resource
    Comparative studies of the quinic acid (qa) cluster in several Neurospora species with special emphasis on the qa-x-qa-2 intergenic region (1991)
    Springer
    Molecular genetics and genomics 230 (1991), S. 337-344 
    Details
    ISSN: 1617-4623
    Keywords: Neurospora crassa ; Neurospora africana ; Quinic acid (qa) cluster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The organization of the quinic acid (qa) genes in Neurospora crassa has been compared to that in several other Neurospora species. This gene cluster was found to be highly conserved in all species examined. However, there are numberous restriction fragment length polymorphisms that distinguish the heterothallic and homothallic species. Catabolic dehydroquinase assays indicated that qa-2 gene expression in the homothallic species is subject to induction by quinic acid, as is the case in N. crassa. The qa-x-qa-2 intergenic region of the homothallic species N. africana was cloned and sequenced. Conserved qa activator (qa-1F) binding sites have been identified in this region. When the qa-x-qa-2 intergenic region of N. crassa was replaced with its N. africana counterpart, qa-2 gene expression was reduced; however repression by glucose appeared normal. Furthermore, the N. africana start site for qa-2 transcription (which differs from the N. crassa start site) was utilized in the transformant. The overall evidence suggests that a weakening of the −120 activator binding site in the qa-x-qa-2 intergenic region may be responsible for these differences.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00280289
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  • 5
    Electronic Resource
    Electronic Resource
    A genetic map of Phycomyces blakesleeanus (1987)
    Springer
    Molecular genetics and genomics 210 (1987), S. 69-76 
    Details
    ISSN: 1617-4623
    Keywords: Phycomyces ; Genetic map ; Tetrad analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Complementation tests among Phycomyces auxotrophic strains revealed the existence of four genes with mutants requiring riboflavin, three genes with purine auxotrophs, two with nicotinic acid auxotrophs, and two with lysine auxotrophs. A total of 134 sexual crosses between strains carrying mutations affecting phototropism (madA-madE), carotenoid biosynthesis (carA), auxotrophy (ribA-ribD, purA-purC, lysA and lysB, nicA and nicB, and leuA) and resistance to 5-fluorouracil (furA and furB) were studied; mating type (sex) was also included as a marker. The results from random spore analysis, tetrad analysis, and gene-centromere distances shows that these markers are distributed into 11 linkage groups.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00337760
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