Tokyo stocks opened higher Monday, boosted by Wall Street gains late last week and a weak yen that lifted Japanese export-related issues. In the first 15 minutes of trading, the 225-issue Nikkei Stock Average rose 324.34 points, or 0.84 percent, from Friday to 38,972.09. The broader Topix index was up 9.94 points, or 0.37 percent, at 2,722.57. On the top-tier Prime Market, gainers were led by transportation equipment, nonferrous metal, and metal product issues. At 9 a.m., the U.S. dollar fetched 146.40-42 yen compared with 146.15-25 yen in New York and 144.93-94 yen in Tokyo at 5 p.m. Friday. …