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  • 1
    ISSN: 1432-0983
    Keywords: Linear plasmids ; Phylogenetic trees
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Relative phylogenetic distances were estimated for those linear plasmids for which sequencing data were available by comparing the amino-acid sequences of the putative DNA- and RNA-polymerases, and phylogenetic trees were calculated. The relationships obtained accord well with those indicated by other structural characteristics of these genetic elements. It is obvious that linear plasmids constitute a separate group of genetic traits when compared with those of the adenoviruses. However, an overall relationship to these viruses is evident. Among the linear plasmids at least two main groups can be recognized, namely the cytoplasmically and the mitochondrially localized elements.
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  • 2
    ISSN: 1432-0983
    Keywords: Key words DMAT-S ; Hydrophobins ; Stress protein ; Ergot alkaloids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In order to identify genes which are expressed during alkaloid synthesis in an axenic culture of Claviceps sp. (strain ATCC 26245), a cDNA library from a producing culture was differentially screened with cDNA from producing (cDNA+) and non-producing (cDNA–) cultures, respectively. Altogether, ten cDNA clones were obtained, the alkaloid-synthesis-correlated expression of which was confirmed by Northern analyses. Evaluation of their nucleotide and derived amino-acid sequences identified one gene unequivocally, coding for dimethylallyltryptophan-synthase (DMAT-S), the initial enzyme of the specific alkaloid pathway. For two other genes significant homologies to known fungal genes were detected: one clone showed homology to the Neurospora crassa ccg1 gene, coding for a clock-regulated putative general stress protein; seven cDNA clones, derived from the same gene, which is highly expressed under these conditions, contained typical hydrophobin domains and long stretches of asparagine/glycine repeats (like QID3 from Trichoderma harzianum), thus probably representing a cell-wall constituent. These data show that this is not only a successful approach to clone genes specific for the alkaloid-pathway of C. purpurea, but also of genes which might be involved in the differentiation of sclerotial hyphae, the prerequisite for alkaloid synthesis.
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  • 3
    ISSN: 1432-0983
    Keywords: Transformation ; Senescence ; Podospora anserina
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In the ascomycete Podospora anserina senescence through strain aging is under nucleo-cytoplasmic control and inducible in juvenile mycelia by an ‘infective principle’ transferred after cytoplasmic contact via anastomoses. A specific DNA called plasmid-like (pl) DNA, present exclusively in aging mycelia, was found to be identical with this ‘infective principle’, since it was possible to transform juvenile protoplasts to senescence by using purified p1DNA. Therefore a specific function may be attributed to this ccc DNA. Its direct involvement in a genetically programed senescence is confirmed and its development as a vector for transfer of genetic information in eukaryotes can be undertaken.
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  • 4
    ISSN: 1432-0983
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 53 (1978), S. 145-149 
    ISSN: 1432-2242
    Keywords: Claviceps life cycle ; Alkaloid production ; Mycelial morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The morphological and physiological evaluation of single ascorspore lines (F1) obtained from 4 production strains of Claviceps purpurea and the subsequent production and evaluation of an F2 from two of these strains has shown: 1. The breeding system responsible for the sexual cycle of C. purpurea is characterized by monoecism and self-compatibility. 2. Heterokaryosis is neither required for the completion of the life cycle nor for alkaloid synthesis. 3. The huge variability in both mycelial morphology and alkaloid spectra makes it evident that all production strains are highly heterogeneous. 4. A correlation between morphology and an alkaloid pattern was not found. 5. Alkaloid production is, however, correlated with distinct genotypes. 6. In some cases an increase in the total alkaloid content and in the formation of specific alkaloids was also found, showing that the genetic control of these metabolites may be accessible. Taken together these results open up the way to concerted breeding with Claviceps purpurea with the object of improving alkaloid production.
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  • 6
    ISSN: 1432-2242
    Keywords: Secale ; mt DNA ; cpDNA ; CMS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Molecular characterization of mitochondrial (mt) DNA of rye (Secale cereale L.), free of significant amounts of contaminating chloroplast (cp) DNA, was initiated using the open-pollinated cultivar ‘Halo’ as a source of mtDNA. Based on the compilation of data from restriction patterns, the molecular size of the mtDNA was estimated to be 410 Kb and its buoyant density was determined as 1.705 g/ml. Southern hybridization, using labelled cp genes (P700 and ribulosebiphosphate-carboxylase large subunit), indicated the presence of cpDNA-homologous regions on putative mtDNA fragments. Mt DNAs of inbred lines with fertile and cytoplasmic male sterile (CMS) ‘Pampa’ cytoplasm were also analysed. Whereas the restriction patterns of mtDNAs of ‘Halors and the fertile line turned out to be identical, ‘Pampa’ mtDNA showed a unique restriction pattern, indicating (as in most other CMS systems) the involvement of mtDNA rearrangements in the expression of male sterility in rye. All 3 mtDNAs investigated contain regions homologous to the plasmid S1 of the CMS-S cytoplasm of Maize (Zea mays), as indicated by hybridization experiments. In ‘Pampa’ cytoplasm the S-homologous sequence is located within a rearranged region of mtDNA.
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  • 7
    ISSN: 1432-2242
    Keywords: CMS-Secale ; RFLP ; Differential transcription ; cob ; atpA ; atp9
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mitochondrial (mt) genomes of rye (Secale cereale L.) lines with “normal” and cytoplasmic male sterility (CMS) inducing “Pampa” cytoplasm were compared by detailed restriction fragment length polymorphism (RFLP) and Northern analyses. RFLP analyses using several heterologous mt genes as probes revealed considerable differences in the overall structure of the two mt genomes. With cob and atpA, the data indicate intragenic recombination and/or different copy numbers of these genes in the two cytoplasms. In spite of this heterogeneity at DNA level, the transcriptional patterns of nine out of ten mitochondrial genes analysed are unaffected. The exception is in the “Pampa” cytoplasm which contains an additional cob-homologous transcript. Since this transcript is strongly reduced in the presence of restorer genes, it might causally be correlated to the CMS phenotype.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 61 (1982), S. 97-100 
    ISSN: 1432-2242
    Keywords: Claviceps purpurea ; Mutants ; Recombination ; Alkaloid production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary With the purpose of improving alkaloid production in Claviceps purpurea, concerted breeding studies were conducted in order to investigate the exchange of genetic material by meiotic recombination. 1) From two homokaryotic strains differing in the amount of ergocristin produced, 52 biochemical variants were obtained including both auxotrophs and fungicide resistants, 38 of which showed virulence. 2) After host passage, sclerotia formation and ascospore production, 9 stable mutants were obtained (1 auxotrophic and 8 resistant). 3) Several cross infections between the mutant auxotrophic for lysine and different resistant mutants were established and the offspring of one cross was evaluated in detail for both segregation of the marker genes and quantitation of alkaloid production. 4) The marker genes segregated in a Mendelian pattern, as was expected for a two factor cross: 50% parental types and 50% recombination types. This shows that both marker genes are unlinked. 5) Independent of the segregation pattern of the marker genes a “segregation” of quantitative alkaloid production was found. All recombinant strains did not only exceed the level of the low producing parent but some of them showed a higher alkaloid yield than the parent with the higher production rate. The general implication of these data is twofold: under controlled conditions it is possible to perform meiotic recombination with a self-fertile parasitic fungus and it is possible to use this technique for strain improvement.
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  • 9
    ISSN: 1432-2242
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 10
    ISSN: 1617-4623
    Keywords: Key words Peptide alkaloids ; D-lysergyl-peptide synthetase ; Dimethylallyltryptophan synthase ; FAD oxidoreductase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A gene (cpd1) coding for the dimethylallyltryptophan synthase (DMATS) that catalyzes the first specific step in the biosynthesis of ergot alkaloids, was cloned from a strain of Claviceps purpurea that produces alkaloids in axenic culture. The derived gene product (CPD1) shows only 70% similarity to the corresponding gene previously isolated from Claviceps strain ATCC 26245, which is likely to be an isolate of C. fusiformis. Therefore, the related cpd1 most probably represents the first C. purpurea gene coding for an enzymatic step of the alkaloid biosynthetic pathway to be cloned. Analysis of the 3′-flanking region of cpd1 revealed a second, closely linked ergot alkaloid biosynthetic gene named cpps1, which codes for a 356-kDa polypeptide showing significant similiarity to fungal modular peptide synthetases. The protein contains three amino acid-activating modules, and in the second module a sequence is found which matches that of an internal peptide (17 amino acids in length) obtained from a tryptic digest of lysergyl peptide synthetase 1 (LPS1) of C. purpurea, thus confirming that cpps1 encodes LPS1. LPS1 activates the three amino acids of the peptide portion of ergot peptide alkaloids during D-lysergyl peptide assembly. Chromosome walking revealed the presence of additional genes upstream of cpd1 which are probably also involved in ergot alkaloid biosynthesis: cpox1 probably codes for an FAD-dependent oxidoreductase (which could represent the chanoclavine cyclase), and a second putative oxido-reductase gene, cpox2, is closely linked to it in inverse orientation. RT-PCR experiments confirm that all four genes are expressed under conditions of peptide alkaloid biosynthesis. These results strongly suggest that at least some genes of ergot alkaloid biosynthesis in C. purpurea are clustered, opening the way for a detailed molecular genetic analysis of the pathway.
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