title: Evidence for an active role of donor cells in natural transformation of Pseudomonas stutzeri.
abstract: The transfer of chromosomal genes in a cell mat of Pseudomonas stutzeri was ca. 10(3) times more efficient per microgram of DNA if DNA was added as a constituent of intact donor cells rather than as a solution. Such intact cell-mediated transfer appears to depend on cell contact. It is independent of the presence of plasmids in donor strains and is DNase I sensitive, thus fitting the usual definition of transformation. It is bidirectional: cells of either strain in a transformation mixture served as the donor and recipients. The donor function in cell contact transformation was inhibited by nalidixic acid but was unaffected by rifampin and streptomycin at growth-inhibiting concentrations. Concentrations of nalidixic acid sufficient to inhibit donor function completely had no effect on the ability of nalidixic acid-resistant recipients to take up DNA from solution. These experiments suggest that certain cells donate DNA to others in the cell mat: they argue against the hypothesis that the function of donor cells is merely cell lysis.
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis; D003227:Conjugation, Genetic; D004269:DNA, Bacterial / Q000096:biosynthesis; D005798:Genes, Bacterial; D009268:Nalidixic Acid / Q000494:pharmacology; D011549:Pseudomonas / Q000235:genetics* / Q000502:physiology; D012329:RNA, Bacterial / Q000096:biosynthesis; D014169:Transformation, Bacterial
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D012329:RNA, Bacterial; D009268:Nalidixic Acid