Examination of growth mode dependent replication dynamics and expression levels for Vibrio parahaemolyticus RIMD2210633.

Replication of bacterial chromosomes increases the copy numbers of genes located near the origin of replication relative to genes located near the terminus. Such differential gene dosage is variable and depends on several factors including replication rate, generation time and chromosome size. For vibrios, a diverse family of fast growing marine living gammaproteobacteria, gene dosage effects may be particularly important as they harbour their genome within two differently sized chromosomes. In this series of experiments, gene dosage at the genomic level and its influence on the expression level has been examined in V. parahaemolyticus. For the genomic analyses, gene copy numbers for bacteria in mid-logarithmic phase grown in rich media (Luria-Bertani containing 3% (w/v) NaCl) at two temperatures (37°C or 20°C) or in minimal media (M9 containing 3% (w/v) NaCl and 0.4% (w/v) glucose) were compared against gene copy numbers for non-replicating cells. For expression analyses, cDNA derived from bacteria in mid-logarithmic phase grown in rich broth at two temperatures (37°C or 20°C) or in minimal media were compared against gDNA from non-replicating cells. Also, cDNA derived from early (OD600=0.2) or mid-logarithmic phase bacteria (OD600=0.5) in rich broth at 37°C, were compared against cDNA derived from mid-logarithmic cells in minimal media (OD600=0.5) or cDNA from early stationary phase rich broth cells (OD600=3.0). Keywords: Comparative genomic and/or cDNA hybridization Samples of genomic DNA and/or cDNA were labeled with Cy3 and Cy5 and cohybridized on six single arrays.