Effects of disruption or overexpression of SylmG1 in Synechococcus elongatus. (A) Gene disruption of SylmG1. Genotypic character of the wild type (WT) and kanamycin-resistant mutants (lines #1-5) which were subjected to PCR analysis using primer 1 (5'-TGACGGACTTCTTCGACCAGATG-3') and primer 2 (5'-ATTGAACCGCGTTGGGACAAGG-3'). A 0.9-kb nptII gene was inserted into SylmG1 locus by homologous recombination. The insertion of the nptII gene was confirmed by PCR using the primer set indicated in the diagram. (B) Overexpression of SylmG1. Total RNA (3 μg) from exponential cells (OD730 = 0.4) of the wild type or spectinomycin-resistant mutants (OX) was subjected to RNA-blot analysis with the SylmG1 specific probe. (C) Phenotype of the SylmG1 disruptant. Nucleoids of the wild type (WT) and the SylmG1 disruptant (ΔSylmG1) were stained with DAPI. Cells in the exponential phase were stained with DAPI and the images were obtained with the same exposure time. The blue is DAPI fluorescence showing the localization of DNA, and the autofluorescence of chlorophyll is red. Bars = 5 μm. (D) Nucleoids of the SylmG1 overexpresser (OX-SylmG1). The image was obtained by the same procedure as (c). The distribution patterns of the cell length of the wild type (WT) and the SylmG1 overexpresser, measured in the exponential phase, are shown in the histograms. The average of the cell length is shown in each graph along with the standard deviation. n = 50. Bar = 5 μm. (E) Relationship between the distribution of nucleoids and the localization of FtsZ in the wild type and the SylmG1 overexpresser. Localization of FtsZ was examined by immunofluorescence microscopy. The green fluorescence shows the localization of FtsZ. The blue is DAPI fluorescence which shows the localization of DNA, and the autofluorescence of chlorophyll is red. Merged images are also shown at the bottom. Bars = 5 μm.