Mobilization of the Proteus morganii Chromosome by R Plasmids

Abstract

R plasmids R702., R711b, R1, D, Rip69, R447b, R471 andiR394, belonging to different incompatibility groups, mobilized the Proteus rnorganii 28 15 chromosome. Matings employing plasmids K711 b or R702 as sex factors with doubly auxotrophic recipients produced recombinants characterized by the obligatory inheritance of ser-I+, irrespective of the selected marker. I N T R O D U C T I O NProteus rnorganii occupies a unique position in the Proteus group. It differs in biochemical aspects as well as in its G + C mole percentage (see Coetzee, 1972). The chromosome of P. rnirabilis is mobilized by various R plasmids (Coetzee, 1978a(Coetzee, , b, 1979a) and a map of the chromosome is available (Coetzee, 1979 b). This paper reports attempts to mobilize the P. morganii chromosome with R plasmids. METHODSBacteria undplasmids. These are listed in Table 1. Media. Nutrient broth and agar were as described by Coetzee ( 1 9 7 8~) .MacConkey agar was from Difco. Minimal medium (MM) was that of Grabow & Smit (1967) containing methionine (4.0 pg ml-l) and calcium pantothenate (5 pg ml-l) and was supplemented with amino acids (40 pg ml-l) when necessary. Incubation temperature was 37 "C.Antibacterial drugs. Ampicillin, chloramphenicol, tetracycline and kanamycin (each 30 pg ml-l), nalidixic acid (75 ,ug ml-l) and streptomycin ( 1 mg ml-l) were added to MM or MacConkey agar when required.Plate matings. These were done by the method of Coetzee ( 1 9 7 8~) . Briefly, equal volumes (0.4 ml) of the partners were mixed and filtered through Millipore membranes which were then placed on nutrient agar and incubated overnight. Growth was harvested and washed with saline and suitable dilutions were plated on selective media and incubated for 4 d. Recombinants were tested for expression of plasmid antibiotic resistance markers by the method of Coetzee (1978a, 19796).Umelected marker analysis. Recombinants (50 to 500) selected for the transfer of a single marker on appropriately supplemented MM were replicated to MM to score prototrophs. R E S U L T S A N D D I S C U S S I O NPlasmids R702, R711b, R1, D, Rip69, R447b, R471 and R394 were stably maintained in P. morganii 28115, had intra-strain transfer frequencies of per donor (not shown) and mobilized the P. morganii chromosome. Plasmids Rip69, R447b, R471 or

Plasmid R394 is a Cointegrate

“…This phage is a derivative of high frequency transducing phage 5006M and originated from transduction of R394 to P. mirabilis strain PM5006 (Coetzee, 1974). The kanamycin resistance marker on the phage 5006M HFT k genome may be located on the hairpin loop structure (Pretorius & Coetzee, 1980) and the present observation is consistent with this. A similar structure was not evident on R394b, supporting the observation than the ampicillin resistance marker on the genome of phage 5006M HFT ak is not located in a hairpin loop structure (Pretorius & Coetzee, 1980).…”

“…The hairpin loop structure observed on R394a was first detected (Pretorius & Coetzee, 1980) on the genome of P. mirabilis phage 5006M HFT k (Coetzee, 1974). This phage is a derivative of high frequency transducing phage 5006M and originated from transduction of R394 to P. mirabilis strain PM5006 (Coetzee, 1974).…”

Optimum frequency band for radio polarization observations

“…An example for the spiral galaxy NGC 6946 is shown in Fig. 5. The spectrum of integrated polarized flux densities is fitted by an IFD model () with σ RM ≃ 34 rad m −2 , in excellent agreement with the analysis of the depolarization map by Beck (2007), or by an EFD model () with σ RM ≃ 20 rad m −2 from the Galactic foreground. With only one more observation at a frequency band below 1.4 GHz, IFD and EFD can be distinguished.…”

“… References: (1) Fletcher et al (2004); (2) Beck (2007); (3) Fletcher et al (2011); (4) Hummel, Beck & Dahlem (1991); (5) Heesen et al (2009); (6) Kim et al (1990); (7) Murgia et al (2004); (8) Vogt & Enßlin (2005); (9) van Weeren et al (2010); (10) Xu et al (2006); (11) Sun & Reich (2009); (12) Laing et al (2008); (13) Feain et al (2009). …”

“… Spectrum of integrated polarized flux densities of the spiral galaxy NGC 6946 and fits with IFD and EFD. The data are computed from the maps by Beck (2007) with the same resolution of 15 arcsec, except for the map centred at 2.675 GHz with 4.4‐arcmin resolution which yields a lower limit. …”