Plasmid mobility

Studies by Levine et al. (1983) have addressed the issue of plasmid mobilizations, the movement of plasmids between different host cells. Human volunteers fed tetracycline along with E. coli HS-4 (typical of the normal intestinal flora of humans) bearing highly mobilized plasmids (e.g., pJBK5) that carried resistance to chloramphenicol and tetracycline became co-colonized with E. coli HS-4 bearing the antibiotic-resistant plasmid. However, the use of a poorly mobilizable plasmid (pBR325) did not result in plasmid transfer. 

Higher rates of horizontal gene exchange, based on the abundant presence of plasmid transfer (Tra), plasmid mobilization (Mob), transposons (Tn), insertion seqnences (IS), and similar fnnctions or elements, seem to be a rule in these variable gene pools. 

Henschke, R. B. Schmidt, R. J. (1990). Plasmid mobilization from genetically engineered bacteria to members of the indigenous soil microflora in situ. Current Microbiology, 20, 105-10. 

In addition, a leader peptide encoded by the opd gene functions to insert the processed parathion hydrolase protein in the membrane of the native Flavobacterium and Pseudomonas diminuta strains but causes the protein to be excreted by Streptomyces lividans (26,28). The ability of these regulatory elements to function across such a wide range of microorganisms is strongly suggestive of the important role that plasmid mobility and recombination have played in the dissemination of the opd gene. 

Plasmid mobilization and marker exchange. The respective deletion-containing sequence was substituted for the wild-type gene in each Pseudomonas strain by double reciprocal recombination to the unaltered flanking regions immediately adjacent to the deleted sequence. In this way we avoided the possibility of creating any... 

Over 4 decades, between 1960 and 2000, the development of new antibiotics used well characterized basic structures for partial synthetic modifications, primarily to overcome resistance by increasing the pharmacodynamic properties and, secondarily, to improve the pharmacokinetic profile of older compounds. However, bacteria rapidly responded by acquiring additional genetic alterations either as mutations or by accumulating resistance genes as part of mobile genetic elements ( integrons) on transferable resistance plasmids. 

Class C Serine p-lactamases AmpC enzymes of coti, Shigella spp., Enterobacterspp., C. freundii, M. morganii, Providencia spp. and Serratia spp. cephalos-porinases with wide spectrum of activity CMY, LAT, BIL, MOX, ACC, FOX and DHA types. All genes are ampC genes that have been mobilized by transfer to plasmid DNA. 

Mob, can be mobilized during conjugation with broad-host-range plasmids Xm, kanamycin resistance Km, kanamycin sensitivity Cm, chloramphenicol Sm, streptomycin 7c, tetracycline. 

Isolation and sequencing of the cellulose synthase gene(s) has not been accomplished yet however, DNA from Acetobacter xylinum containing this gene(s) was cloned into broad host-range plasmid vectors (82). These vectors were mobilized into Pel- mutants to test for complementation. To date, this approach has not produced a pellicle-forming transconjugant from a Pel- mutant of Acetobacter (82). The direct correlation between cellulose production and presence of plasmid DNA in Acetobacter has been reported... 

A number of characteristics of plasmids are significant in relation to the development of bacterial resistance. These include the encoding of resistance capability for as many as six unrelated antibiotics in the same DNA material, the capacity to transfer from one cell to another and thus disseminate the resistance, and the mobilization by which ordinarily nontransferable gene fragments can be transferred by the plasmid from one bacterial cell to others. Plasmids are of varying size and have been identified in most bacteria. Their majority carries resistance determinants for two or more antibiotics not of the same chemical class. It appears that two identical plasmids cannot coexist in one cell, but plasmids of different groups can occur, increasing even further the possibilities for resistance spread. The transfer or acquisition of other plasmid-mediated characteristics, such... 

The NAH and TOL plasmids which encode naphthalene and toluene degradation represent discrete, mobile genetic systems that are easily transferred and selected. This tendency to focus on systems according to the ease of genetic manipulation led... 

Studies designed to test the mobilization and persistence of recombinant catabolic plasmid pDlO. 

Hill, K. E.,Fry, J. C. Weightman, A. J. (1994). Gene transfer in the aquatic environment persistance and mobilization of the catabolic recombinant plasmid pDIO in the epilithon. Microbiology, 140, 1555-63-... 

What assumption is made about the relative electrophoretic mobility of bromophenol blue dye and plasmid DNA ... 

---