Tokyo stocks opened lower Wednesday, weighed down by overnight falls on Wall Street and concern over growing instability in the Middle East. In the first 15 minutes of trading, the 225-issue Nikkei Stock Average fell 487.27 points, or 1.26 percent, from Tuesday to 38,164.70. The broader Topix index was down 14.55 points, or 0.54 percent, at 2,676.23. On the top-tier Prime Market, decliners were led by electric appliance, chemical, and information and communication issues. At 9 a.m., the U.S. dollar fetched 143.72-74 yen compared with 143.52-62 yen in New York and 144.16-19 yen in Tokyo at 5 p….