Tokyo stocks opened slightly higher Thursday as exporter issues were sought after the yen continued its slide against the U.S. dollar to a fresh 20-year low. In the first 15 minutes of trading, the 225-issue Nikkei Stock Average rose 53.82 points, or 0.19 percent, from Wednesday to 28,288.11. The broader Topix index was up 2.35 points, or 0.12 percent, at 1,972.33. On the top-tier Prime Market, gainers were led by mining, information and communication, and transportation equipment issues. At 9 a.m., the dollar fetched 134.45-46 yen compared with 134.24-34 yen in New York and 133.57-59 yen in T…