ABSTRACT
ABSTRACT: Objective To evaluate the effects of DNA examination of trace bloodstain samples from the scene collected with Trace Biological Evidence Collection kit. Methods Venous blood was made into bloodstains on the ground. The trace bloodstain samples were collected with Trace Biological Evidence Collection kit and common methods, respectively. DNA examination of trace bloodstain samples ï¼50 from each groupï¼ was conducted on the constant temperature shaker for 2, 24, 48, 72, and 96 h, respectively, and the examination results of every group were compared. Results When the trace bloodstain samples were placed on the constant temperature shaker for 24, 48, 72, and 96 h, the DNA detection rates in the group which used Trace Biological Evidence Collection kit ï¼100.00%, 100.00%, 100.00%, 96.00%ï¼ were significantly higher than those in the group using common methods ï¼62.00%, 26.00%, 10.00%, 0ï¼, the differences had statistical significance ï¼P<0.05ï¼. When the trace bloodstain samples were placed on the constant temperature shaker for 2 h, the differences of DNA detection rates between the two groups had no statistical significance ï¼ P>0.05ï¼. Conclusion The Trace Biological Evidence Collection kit can effectively improve DNA detection rate and extend detection time limit for trace bloodstain samples from the scene that have been stored for a relatively long time.
Subject(s)
Blood Stains , DNA , Forensic Medicine , TemperatureABSTRACT
OBJECTIVES: 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 1 µL 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 AmpFâSTR™ Identifiler™ Plus PCR kits. The results of STR typing were compared between different groups. RESULTS: DNA were extracted immediately after benzidine test. Totally STR loci ï¼3.80±1.34ï¼ were detected by silica bead method, while no STR loci were obtained by Chelex-100 method. Thirteen samples ï¼21.7%ï¼ with whole STR typing results were obtained by drying after benzidine test, and the STR locus number ï¼12.90±1.49ï¼ which obtained by silica bead method was much higher than by Chelex-100 method ï¼4.70±1.96ï¼ ï¼P<0.05ï¼. When DNA was extracted immediately after the addition of glacial acetic acid, the STR locus number was ï¼9.40±2.09ï¼ 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. CONCLUSIONS: 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.
