ABSTRACT
Objective To explore the effect of benzidine test and related reagents on DNA analysis of bloodstain. Methods A total of 970 bloodstain filter paper samples with 1μL venous blood were collected, and 10 of them acted as control samples. After benzidine test and related reagent processing, DNA of 960 samples was extracted by Chelex-100 and silica bead methods and then multiplex amplified by AmpF(e)STRTM IdentifilerTM Plus PCR kits. The results of STR typing were compared between different groups. Results DNA were extracted immediately after benzidine test. Totally STR loci (3.80±1.34) were detected by silica bead method, while no STR loci were obtained by Chelex-100 method. Thirteen sam-ples (21.7％) with whole STR typing results were obtained by drying after benzidine test, and the STR locus number (12.90±1.49) which obtained by silica bead method was much higher than by Chelex-100 method (4.70±1.96) (P<0.05). When DNA was extracted immediately after the addition of glacial acetic acid, the STR locus number was (9.40±2.09) by silica bead method, but no STR typing result was obtained by Chelex-100 method. All 15 STR loci could be obtained by only adding glacial acetic acid after drying and only adding tetramethylbenzidine alcoholization liquid or 3％ hydrogen peroxide liquid. Conclusion Benzidine test has significant influence on DNA analysis of bloodstain. The Chelex-100 method is not suitable for the DNA extraction of bloodstain after benzidine test. Drying after benzidine test and silica bead methods can effectively enhance the STR locus number of bloodstain.
ABSTRACT
Objective To discuss the effect of DNA extraction of bloodstain on the filter paper with four methods of solid phase absorption.Methods 180 bloodstain samples on the iflter paper, each one contains 1 microlitre anticoagulation peripheral venous blood, divided into 4 groups with 45 samples, respectively. All samples were treated with four methods of solid phase absorption, i.e. DNA IQ? System, D-shield sensitive DNA Extraction Kit, High efficiency Silica Bead DNA Extraction Kit and Conventional silica bead method. The concentration of DNA and the results of STR typing of four groups were compared each other.Results The concentration of DNA was 3.764±1.790μg/mL and 3.634±1.112μg/mL by using D-shield sensitive DNA Extraction Kit and High efifciency Silica Bead DNA Extraction Kit, respectively. However, the concentration of DNA by using Conventional silica bead method group (3.350±1.250) was not signiifcantly different from each other (P<0.05), while the concentration of DNA extracted with above three methods were higher than by using DNA IQ? System (1.864±1.207)(P<0.001); Signiifcant differences of peak height existed between DNA IQ? System and other three methods (P<0.001); As the same time, the peak height of samples by using High efficiency Silica Bead DNA Extraction Kit and Conventional silica bead method were signiifcantly different from D-shield sensitive DNA Extraction Kit (P<0.01).Conclusions The DNA extracted in bloodstain on the iflter paper by using D-shield sensitive DNA Extraction Kit, High efifciency Silica Bead DNA Extraction Kit and Conventional silica bead method was more than DNA IQ? System. Meanwhile, the quality of DNA using High efifciency Silica Bead DNA Extraction Kit and Conventional silica bead method may be higher.