Tokyo stocks opened slightly higher Friday as rising oil prices boosted energy-related issues, although advances were capped ahead of the release of U.S. employment data later in the day. In the first 15 minutes of trading, the 225-issue Nikkei Stock Average rose 78.45 points, or 0.20 percent, from Thursday to 38,630.51. The broader Topix index was up 7.49 points, or 0.28 percent, at 2,691.20. On the top-tier Prime Market, gainers were led by mining, oil and coal product, and precision instrument issues. At 9 a.m., the U.S. dollar fetched 146.86-87 yen compared with 146.92-147.02 yen in New Yo…