Tokyo stocks opened lower Friday, weighed down by technology issues tracking declines of their U.S. counterparts overnight, but losses were limited by buybacks after the Nikkei index logged its steepest point drop in eight years. In the first 15 minutes of trading, the 225-issue Nikkei Stock Average fell 39.08 points, or 0.10 percent, from Thursday to 37,830.43. The broader Topix index was down 2.24 points, or 0.08 percent, at 2,707.62. On the top-tier Prime Market, decliners were led by insurance, and electric power and gas issues. At 9 a.m., the U.S. dollar fetched 153.68-69 yen compared wit…