Tokyo stocks opened lower Monday as falling oil prices prompted selling of energy-related issues, while political uncertainty weighed ahead of Japan’s general election. In the first 15 minutes of trading, the 225-issue Nikkei Stock Average fell 134.87 points, or 0.35 percent, from Friday to 38,846.88. The broader Topix index was down 11.26 points, or 0.42 percent, at 2,677.72. On the top-tier Prime Market, decliners were led by electric power and gas, bank and insurance shares. At 9 a.m., the U.S. dollar fetched 149.61-62 yen compared with 149.48-58 yen in New York and 150.08-11 yen in Tokyo a…