[摘要]：Tissue specific genes that contain high GC segments are difficult to amplify by standard PCR. We report an improved method for successful amplification of gene segment that has > 70% GC base pairs. This new method of touch down PCR differed by having an initial annealing temperature (Ta) 1.5 degrees C below the primers melting temperature that descended 0.2 degrees C per cycle for 20 cycles and continued thereafter at fixed Ta for next 15 cycles. Different co-solvents were tested with this method to improve the result and betaine proved better than the other co-solvents. This new method is economical, fast and specific in amplifying GC rich region of other genes also. (C) 2012 Elsevier B.V. All rights reserved.
