Abstract: Objective To establish a method of preparing and analyzing DNA of sperm cells from sample mixtures.Methods Sperm cells were captured by micromanipulation method,DNA template was prepared from these sperm cells,and then amplified by multiple displacement amplification(MDA).Results High-yield of highly integrated DNA was produced by MDA from very small amount of DNA template of 20 sperm cells.The DNA could be amplified at least 30 000-fold,and the length of most the DNA segments were greater than 15kb,providing sufficient amount of short tandem repeat(STR) products for DNA genotyping.Conclusion The micromanipulation method is efficient to isolate sperm cells from sample mixtures and multiple displacement amplification can provide sufficient amount of DNA products for STR genotyping.The method seems to be feasible in detecting DNA from rape cases.

Key words: forensic physical evidence, micromanipulation method, sample mixtures, sperm cells, multiple displacement amplification, genome amplification, STR