Biomedical subjects

P Durrens

Publications and source records attributed to P Durrens.

21 records · Page 2Linked to original sources

PubMed1986

Heterologous insertion of transforming DNA and generation of new deletions associated with transformation in Aspergillus nidulans.

The analysis of four transformants for the proline catabolism (prn) gene cluster of Aspergillus nidulans is reported. Using a combination of traditional genetic methodology and Southern hybridisation we have shown that in two cases multiple copies of the transforming plasmid have been integrated into linkage groups other than VII, which contains the prn cluster. In the other two cases integration of the plasmid has probably occurred homologously. The phenotype of these transformants is broadly consistent with increased copy number resulting in increased expression. Genetic manipulation of these transformants using the sexual or parasexual cycles has shown that recombination events during and possibly also subsequent to integration of the transforming DNA can generate new mutational lesions, in particular, deletions.

Aspergillus nidulans↗

PubMed1983

Podospora mutant defective in glucose-dependent growth control.

A mutation (modE), previously described as a membrane mutation, results in several modifications of the female developmental cycle: a high density of protoperithecia, the unscheduled development of protoperithecia into sterile perithecia on the homokaryons of each mating type, and the independence of ascospore outgrowth from the substances normally required for germination. Cultured in liquid medium, the modE strain showed two additional specific features: a higher growth yield than that of wild-type cultures (plus 10% of dry weight) and an extreme reduction of cell life span. Both mutant traits were specific to glucose limitation. Despite the large difference existing in the sensitivity of cells to glucose starvation, the glycogen and trehalose reserves of mutant and wild-type cells were nearly identical. Considered together, these results suggest that the primary effect of the mutation lies in the disruption of a glucose-dependent regulation controlling the transition of the metabolic pattern of cells from growth to quiescence.

Ascomycota↗

PubMed1979

Podospora anserina mutant defective in protoperithecium formation, ascospore germination, and cell regeneration.

A mutant (modx) was selected on the basis of the suppression of self-lysis due to a recessive mutation (modB). modx, a dominant mutation, reduced hyphal branching from nonapical cells, abolished protoperithecium formation, and induced the death of stationary cells only when these were isolated to obtain further development. Mutant ascospores, formed in the fruiting bodies which occasionally occur under specific conditions (32 degrees C on starved medium), showed a delay in the germination process (up to 3 months instead of about 5 h for wild-type ascospores) when submitted to incubation under standard conditions (26 degrees C on germination medium) and failed to germinate at 18 degrees C. Revertants from modx strains, selected on the basis of the suppression of the nonrenewal of growth from stationary cells, were wild type for all the other three defects. Indirect arguments suggested that the modx mutant strain might be defective in the control of a specific class of stable messenger ribonucleic acids which would be essential for the physiology of ascospores and stationary cells.

Alleles↗