Tokyo stocks opened higher Wednesday, tracing overnight gains on Wall Street where the Dow Jones Industrial Average closed at a six-week high. At 9:15 a.m., the 225-issue Nikkei Stock Average gained 142.09 points, or 0.99 percent, from Tuesday at 14,453.76. The broader Topix index of all First Section issues on the Tokyo Stock Exchange was up 6.52 points, or 0.55 percent, at 1,188. 16.