Fig. 6

Classification and up- and down-regulated ratios of candidate genes related to transmembrane transport of substances. Up- or down-regulation of candidate genes in the blue-shelled groups was defined relative to the expression levels in the white-shelled groups. The red areas represent the ratios of upregulated genes, and the green for the downregulated ratios. The numbers of up- and downregulated genes are showed in the pie graphs. Letters from A to E near the pie graphs represent different hierarchies of transport-related functions; Letter “A” represents the most general classification, and “E” represents the most specific classification. Brief descriptions for each classification were given in the figure. Detailed GO annotations and lists of candidate genes were summarized in Additional file 5. Asterisk (*) in the upper right of C1 indicated that the GO category was significantly (P < 0.05) overrepresented