Tokyo stocks opened lower Thursday, weighed down by moves to lock in gains from a sharp rise the day before, with sentiment dampened by declines on Wall Street overnight. In the first 15 minutes of trading, the 225-issue Nikkei Stock Average fell 356.48 points, or 1.07 percent, from Wednesday to 33,089.42. The broader Topix index was down 19.54 points, or 0.82 percent, at 2,367.66. On the top-tier Prime Market, decliners were led by mining, marine transportation, and oil and coal product issues. At 9 a.m., the U.S. dollar fetched 147.17-18 yen compared with 147.25-35 yen in New York and 146.96…