Intergeneric Bacterial Matings

Baron, L. S.; Gemski, P.; Johnson, E. M.; Wohlhieter, J. A.

doi:10.1128/mmbr.32.4_pt_1.362-369.1968

Cited by 50 publications

(33 citation statements)

References 18 publications

(15 reference statements)

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“…From the results of this study, it is evident that a substantial amount of E. coli DNA can be conserved as a single, continuous, genetically complete segment in S. typhosa Hfr WR4000. The existence of continuous E. coli genetic segments of comparable lengths in some hybrids of S. typhosa WR4200 was inferred previously from segregation patterns (1)(2)(3), and from the results of DNA hybridization studies (9), but it has not been demonstrable. The demonstration of the presence of such diploid segments in S. typhosa Hfr WR4000 favors the notion that continuous E. coli DNA segments of this length can be maintained in S. typhosa WR4200.…”

Section: Discussionmentioning

confidence: 88%

“…An insertion of this type could place the origin of the diploid segment in the same chromo-somal position relative to F that it occupied in the parental Hfr. The idea of a chromosomal insertion of the diploid E. coli gene segment has been considered previously as a possible mechanism for diploidy in both the S. typhosa and P. mirabilis intergeneric mating systems (1). At present, however, the manner in which diploid segments are conserved is unknown, either in intergeneric mating systems, in which diploidy occurs commonly, or in E. coli K-12 where, except in recombination-deficient strains (15), the occurrence of this phenomenon is rare.…”

Section: Discussionmentioning

confidence: 99%

“…In previous studies on the genetic hybridization of Salmonella typhosa strains with Escherichia coli Hfr donors, we observed the formation of heterozygous, partial diploid S. typhosa hybrids (1)(2)(3)(4)13). In these hybrids, the transferred E. coli genes usually persist without replacing the homologous S. typhosa alleles on the host chromosome.…”

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confidence: 94%

“…Because only a part of the chromosomal material of the E. coli parent is conserved, the S. typhosa hybrid is diploid with regard to those of its genes which are matched by the inherited E. coil alleles, and haploid with respect to the remainder of its genome. This condition of the Salmonella hybrid is often an unstable one, and segregants which appear to have lost part or all of the E. coli deoxyribonucleic acid (DNA) may be obtained (1,3). The formation of partial diploid hybrids seems to be a common feature of intergeneric matings, having been observed also in crosses between E. coli and Shigella flexneri (10) and in matings between E. coli and Proteus mirabilis (11).…”

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Conservation and Transfer of Escherichia coli Genetic Segments by Partial Diploid Hfr Strains of Salmonella typhosa

1970

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Heterozygous, partial diploid hybrids were obtained in a Salmonella typhosa Hfr strain by using it as the recipient in a mating with the Escherichia coli Hfr donor WR2004 (O... proA ... leu ). Three of these S. typhosa Hfr hybrids were observed to mobilize and transfer the diploid E. coli genes, at high frequencies, to an E. coli recipient. The gradient of transfer frequencies of E. coli markers from these S. typhosa Hfr hybrids was similar to that observed with E. coli Hfr WR2004, from which they were derived. Interrupted matings with one of these S. typhosa Hfr hybrids, designated WR4272, showed the entry times for the pro A, thr − leu , and argB E. coli diploid markers to be identical to the times obtained for these markers with E. coli Hfr WR2004. Also, the pattern of unselected inheritance of the diploid E. coli markers of S. typhosa Hfr hybrid WR4272 was similar to that observed with the chromosomal markers of E. coli Hfr WR2004. It was concluded that S. typhosa Hfr hybrid WR4272 contains, in addition to its Salmonella genome, a physically continuous E. coli chromosomal segment which is genetically complete from proA to at least the strA locus. The two other S. typhosa Hfr hybrids, on the basis of transmission frequency gradients, appeared to contain a continuous E. coli diploid segment complete from proA through the fuc locus. Other classes of S. typhosa Hfr hybrids, derived from mating with E. coli Hfr WR2010 (O... tna ... xyl ), were also observed to transfer E. coli genes at high frequency.

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Section: Discussionmentioning

confidence: 88%

Section: Discussionmentioning

confidence: 99%

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confidence: 94%

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confidence: 99%

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Conservation and Transfer of Escherichia coli Genetic Segments by Partial Diploid Hfr Strains of Salmonella typhosa

1970

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“…(1) Integration of genes into the genome of recipient bacteria is known to be dependent on sequence homology between the captured DNA and that of the recipient bacteria, and it seems that the degree of heterology between these sequences is the main factor determining the barrier to the stable introduction of diverged DNA in bacteria [143–148]. Indeed, Vulic et al [148]observed exponentially decreasing recombination frequencies in enterobacteria with increasing sequence divergence of the introduced DNA.…”

Section: Possible Barriers To Horizontal Gene Transfer In Bacteriamentioning

confidence: 99%

Horizontal gene transfer from transgenic plants to terrestrial bacteria – a rare event?

Nielsen

Bones

Smalla³

et al. 1998

FEMS Microbiol Rev

179

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Today, 12 years after the first field release of a genetically modified plant (GMP), over 15,000 field trials at different locations have been performed. As new and unique characteristics are frequently introduced into GMPs, risk assessment has to be performed to assess their ecological impact. The possibilities of horizontal gene transfer (HGT; no parent-to-offspring transfer of genes) from plants to microorganisms are frequently evaluated in such risk assessments of GMPs before release into the field. In this review we indicate why putative HGT from plants to terrestrial (soil and plant associated) bacteria has raised concern in biosafety evaluations. Further, we discuss possible pathways of HGT from plants to bacteria, outline the barriers to HGT in bacteria, describe the strategies used to investigate HGT from plants to bacteria and summarize the results obtained. Only a few cases of HGT from eukaryotes such as plants to bacteria have been reported to date. These cases have been ascertained after comparison of DNA sequences between plants and bacteria. Although experimental approaches in both field and laboratory studies have not been able to confirm the occurrence of such HGT to naturally occurring bacteria, recently two studies have shown transfer of marker genes from plants to bacteria based on homologous recombination. The few examples of HGT indicated by DNA sequence comparisons suggest that the frequencies of evolutionarily successful HGT from plants to bacteria may be extremely low. However, this inference is based on a small number of experimental studies and indications found in the literature. Transfer frequencies should not be confounded with the likelihood of environmental implications, since the frequency of HGT is probably only marginally important compared with the selective force acting on the outcome. Attention should therefore be focused on enhancing the understanding of selection processes in natural environments. Only an accurate understanding of these selective events will allow the prediction of possible consequences of novel genes following their introduction into open environments.

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Übertragung von F′‐Plasmiden aus Escherichia coli in Proteus mirabilis

Fleischhacker¹,

Böhme²

1979

J of Basic Microbiology

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( E i n g e g a y e n am 28.12.1977)The t'mk of this work was the est'ablishment of an effect,ive t'ransfer system for F'-plasniids from Esc1,eticlkin coli to Pr0teu.s mircrbilis. It. is shown t,liat cellfi of PG VI act as recipients in crosses wit,li E. coli F' st'rains but wit'h a low transfer rate of the plasmid. The presumption that a rest'riction -modification system in P. inirabilis was the only reason for t h e low transfer could not be confirmed.An indirect selection method was developed to isolate P. m.irabili.9 rells which are better recipients. Conjugation experiments showed that the isolated niuta~nt~s had a bett,er recipient' rapacity (increase of about 100). This is true riot only for t,he t,raiisfer of a F'-plasmid but also for a Rplasmid. The stability of t'hese plasmids in the mut,ant cells, however, was much lower than in the wild type.

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Intergeneric Bacterial Matings

Cited by 50 publications

References 18 publications

Conservation and Transfer of Escherichia coli Genetic Segments by Partial Diploid Hfr Strains of Salmonella typhosa

Conservation and Transfer of Escherichia coli Genetic Segments by Partial Diploid Hfr Strains of Salmonella typhosa

Horizontal gene transfer from transgenic plants to terrestrial bacteria – a rare event?

Übertragung von F′‐Plasmiden aus Escherichia coli in Proteus mirabilis

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