Figure 3

Heat map visualizations of gender-selective genes in liver and kidney. The color scale indicates the ratio of expression in males relative to females in the visualizations created using default settings in TreeView [32]. Red indicates higher average expression in males, green indicates higher expression in females, black indicates no significant difference between males and females, and gray indicates that no data was available due to the smaller genome coverage by the RGU34A arrays used by institutions 1 and 3 (numbers above columns indicate the institution that contributed the data). All other institutions used RAE230A or RAE230 2.0 arrays. (A) The left panel shows liver selective genes with a ratio range of 200 to -190, the middle panel shows kidney selective genes with a ratio range of 113 to -89, and the right panel shows gender-predominant genes that have the same or opposite direction of expression in liver and kidney over a ratio range of 81 to -190. Only those genes that were altered in at least two-thirds of sites for kidney, at least half of the sites for liver, or three-quarters or more of the sites in cross-tissue comparisons are shown. (B) Verification of identified classes of gender-selective genes. Genes that exhibited significantly altered expression between males and females in liver or kidney were divided into 8 different groups based on expression behavior as indicated on the right side of the panel. Groups 1, 2, 7 and 8 exhibited gender-selective expression in both liver and kidney. Groups 3 and 4 exhibited gender-selective expression predominantly in liver and groups 5 and 6 exhibited gender-selective expression predominantly in kidney. The expression of four to five genes from each of the groups was examined by RT-PCR (column C) in liver and kidney from control male and female F344 rats from an independent study. The relative ratios span a range from 300 to -267.