ABSTRACT
Objective To establish a method of sperm DNA extraction in mixed stain by using DNase-Ⅰ purificationcombined with alkaline lysis method in forensic science.Methods 79 mixed stain samples of criminal cases were collected.Sperm DNA was extracted using the purification of DNase-Ⅰ binding alkaline lysis method.16 STR loci were genotyped with fluorescent multiplex amplification system.The typing results were compared with that of extracted using two-step differential extraction procedure.Results Of all 79 mixed stain samples,64 samples were genotyped successfully by using DNase-Ⅰ purification combined with alkaline lysis method while 57 samples were genotyped successfully with two-step differential extraction procedure.There was significant difference between two methods(P=0.039).The purification of DNase-Ⅰ binding alkaline lysis method had a higher success rate and lower cost than that of two-step differential extraction procedure.Conclusion Purification of DNase-Ⅰ binding alkaline lysis method can increase the typing success rate of the mixed stain samples.The method is simple,rapid and easy to be automated,and suitable for forensic identification test.
ABSTRACT
1.8.PCR was performed using the human Gpx-1 gene,and we obtained the needed target gene fragments.Conclusion The alkaline lysis extraction method is reliable for obtaining high quantities of DNA from blood clot suited for PCR amplification.