Conserved and different modules in metabolic network between chloroplasts and Synechococcus sp. WH8102 (syw). The modular structures of enzyme-centric networks for chloroplasts and syw are shown in (A) and (B) respectively. Each module is represented by a specific color. The five pairs of modules with same color are conserved modules between chloroplast and syw, among which the yellow, green and blue modules correspond to amino-acid metabolism, the light-orange and pink modules belong to carbohydrate metabolism and nucleotide metabolism respectively. The picture was drawn using the Pajek program.