par Gratia, Jean-Pierre 
Référence Annals of microbiology, 64, 4, page (1789-1796)
Publication Publié, 2014-11
Référence Annals of microbiology, 64, 4, page (1789-1796)
Publication Publié, 2014-11
Article révisé par les pairs
| Résumé : | Spontaneous zygogenesis (or Z-mating), unlike F-mediated conjugation, promotes the formation of complete zygotes. It is interpreted as a phage-induced process of cell fusion. Most Z-mating products have proven phenotypically unstable, losing part of the phenotype for which they were selected. Persistent Z-mating products in our study were stable genetic recombinants or were noncomplementing diploids, consisting of either parental types, or one of them plus a recombinant type. We investigated their fate in crosses between Escherichia coli K12 strains carrying chromosomally-inserted aminoglycoside resistance cassettes. The use of such strains, in addition to mutants carrying recessive mutations of resistance to various drugs, provided new means to follow the evolution of noncomplementing diploids exhibiting one parental or recombinant type and allowed us to visualize their switching to the other phenotype. Switching between noncomplementing forms has been found to require a phase of complementation. Two events can be distinguished by the response to environmental stresses, one consisting of a final switching, apparently not influenced by incubation conditions, and the other revealed as a transient transfer of phenotypic expression from one genome to the other and found to be caused by heat shock or starvation. |
