The Japanese yen slipped to a new 20-year low in the 129 zone against the U.S. dollar Wednesday morning in Tokyo, coming under renewed pressure on the prospect of a further widening in the interest rate gap between the two countries. The yen bounced back to the upper 128 levels in late morning trading after briefly dropping to around 129.40. On the stock market, the 225-issue Nikkei Stock Average rose 154.90 points, or 0.57 percent, in the morning session from Tuesday to 27,139.99. The broader Topix index was up 14.20 points, or 0.75 percent, at 1,909.90. On the top-tier Prime Market, gainers …