g., Selleckchem TPX-0005 Pseudomonas putida as recipient almost exclusively in stationary phase cultures with frequencies of self-transfer ≈ 10-2 per donor. Self-transfer rates are highest in stationary phase cells grown with 3-chlorobenzoate and lower with fructose [27]. In line with this, expression of the promoter for the integrase is highest after growth on 3-chlorobenzoate, lower on fructose and essentially absent on glucose [26]. Because of the conservation of the ICEclc core region among different GEIs we were interested to study its transcriptional organization, as a further step towards the

understanding of the life-style program of this class of mobile elements. Figure 1 Global gene organization of ICE clc and strategy for

analysis of the core region transcriptional units. A) Approximate locations of the ICEclc variable and core regions, with indication of gene functions known so far. Open reading frames are indicated by open (plus strand) or grey boxes (minus strand). Small numbered black stripes above point to the location of the probes used for macroblot hybridizations. B) Detailed gene structure of the core region with positions and results of RT-PCR analysis, and placement of transcript lengths (dashed lines) revealed by Northern analysis using the probes indicated as black numbered bars OSI-744 below the scale bar. RT-PCR indications are the following: stippled line indicates reverse transcribed regions. Solid line with two upright ends indicates the amplified region. A ‘minus’ within a circle indicates that no amplicon was obtained for that region. ORF numbering for ICEclc as in Genbank AJ617740. In order to resolve the global transcription network of ICEclc in P. knackmussii B13, we carried out a combined approach of Northern hybridizations, reverse-transcriptase polymerase chain reaction (RT-PCR), semi-tiling array hybridization and Rapid Amplification of cDNA Ends (5′-RACE). We detected Paclitaxel fifteen transcripts, some of which were expressed to high levels in stationary phase cultures, but — interestingly,

not with all carbon sources. Results Transcriptional organization of the ICEclc core region In order to analyze the transcriptional organization aminophylline of the core region of ICEclc, we used a combination of conventional molecular techniques and semi-tiling micro-array analyses. The ICEclc core spans the region between nucleotide 50,000 until the left end of the element (position 102,843; ICEclc numbering, GenBank Accession Number AJ617740), and comprises the most conserved stretch among a number of closely related GEI [24, 26]. Furthermore, it includes the integrase gene at the other side of ICEclc (Figure 1A). Figure 1 schematically presents the analysis of intergenic regions in the ICEclc core region, whilst combined RT-PCR results are shown in Figure 2. RT-PCR provided a first view of potentially linked polycistronic mRNAs.