Tokyo stocks opened lower Tuesday as investors locked in gains after sharp rises the previous day, with many awaiting the outcome later in the day of the Bank of Japan’s policy meeting. In the first 15 minutes of trading, the 225-issue Nikkei Stock Average fell 237.52 points, or 0.60 percent, from Monday to 39,502.92. The broader Topix index was down 2.77 points, or 0.10 percent, at 2,719.22. On the top-tier Prime Market, decliners were led by precision instrument, pharmaceutical and marine transportation issues. At 9 a.m., the U.S. dollar fetched 149.14-15 yen compared with 149.09-19 yen in N…