Application of Automatic Nucleic Acid Extractor Combined with Vacuum Concentrator in Forensic Science / 法医学杂志

Objective To explore the application value of automatic nucleic acid extractor combined with vacuum concentrator in forensic DNA extraction. Methods Gradient samples of human peripheral venous blood were collected at 40, 80, 120, 160, 200, 240, 280 and 320 fold dilution. The samples of each gradient were treated with no inhibitor, black oil, rust, fruit acid, tin foil and indigo, respectively. The automatic nucleic acid extractor was used for DNA purification and extraction of the above samples. The extracted DNA eluent （6 μL） was taken for amplification directly, and the rest was concentrated by vacuum concentrator. DNA was amplified and examined using the Investigator 26plex QS kit before and after concentration. Results Only gradient samples treated with fruit acid obtained complete STR typing results at 40 fold dilution. The other 5 methods obtained complete STR typing results at 40-160 fold dilution. The results of STR typing after DNA concentration showed that the average peak height and detection rates of gene loci both increased to a certain extent, but the effect was not obvious. Conclusion The automatic nucleic acid extractor has an efficient inhibitor removal ability and high extracting efficiency of DNA. The vacuum concentrator can concentrate DNA samples to a certain extent. Combining the automatic nucleic acid extractor with the vacuum concentrator can improve the examination success rate of forensic materials.

DNA fingerprinting identification of bile power(bile)medicines / 中国中药杂志

The pig bile powder, bovine bile powder, snake bile, sheep bile, goose bile powder, and bear bile powder were contained by the Chinese Pharmacopoeia. The bile power medicine has a long history in traditional Chinese medicine and definite effect. However, the medicine of bile powder(bile) are similar in morphology. Besides, many medicine lack specific microscopic identification characteristics and chemical characteristics. There is a risk of adulteration, especially when the fake medicine were mixed in authentic medicine, it is difficult to detection. The key to control the quality and ensures the clinical efficacy is the good or bad, true or false of the bile power medicine. The STR typing technology is a method that according to differential typing of PCR amplified lengths to compare and identify individual organisms. Based on the principle of STR typing, the easily, rapid DNA fingerprinting method to identify the bile power and adulteration was established.The original animal or bile powder of pigs, cattle, sheep, chickens, ducks, geese, snakes, bears, fish were collected, the 12 S-L1091/12 S-H1478 and 16 S-L3428/16 S-H3667 was obtained by sifted, the DNA fingerprinting of the bile power and adulteration was obtained by STR typing. Every species has different STR fingerprints, so different species can be identified. Besides, the fingerprints have both the authentic and fake's information, the adulteration of authentic and fake can be identified. Therefore, the method to identify the bile power and adulteration was achieved through the combination of two primers. The DNA fingerprinting method established in this study can also be used for other animal medicine.

Effect of Benzidine Test on DNA Analysis of Bloodstain / 法医学杂志

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.

Study on the preparation method of capillary electrophoresis sieving medium based on domestic genetic analyzer / 中国法医学杂志

Objective To prepare a capillary electrophoresis sieving medium and apply it in GA118-16A genetic analyzer. Methods The white solid polyacrylamide (LPA) was prepared by polymerization and lyophilized. Through the swelling of the sol buffer, the sieving medium was obtained. The sieving medium was evaluated by 1) characterizing the parameters, including molecular weight, structure and viscosity, 2) applying in the GA118-16A genetic analyzer, including the spatial calibration, the spectral calibration and the STR analysis.. Results The prepared sieving medium Mw 1.8 x 105Da, Mn 1.2 x 105 Da, is of correct structure and high purity. The polydispersity was 1.5The spatial calibration and spectral calibration files can be established successfully in GA118-16A genetic analyzer, and the sieving medium can effectively separate the DNA fragments with 1bp difference. The STR profile is of sharp peaks, no impurity peaks, no tail, and no peak loss. Conclusion The sieving medium prepared by the method can be applied to domestic genetic analyzer such as GA118-16A.

The application of whole genome amplification in DNA typing of trace samples / 中国法医学杂志

Objective To explore the effectiveness of whole genome amplification technology in DNA typing of trace samples.Methods Simulated trace samples which contain 1～20 cells were prepared by micromanipulation.Whole genome amplification was added before conventional PCR-STR typing step,to compare the effectiveness of PEP and MDA in DNA typing of trace samples from four aspects i.e.allele imbalance,allele drop-out,locus drop-out and pseudo allele (which contains the stutter peak).Results Amplification efficiency of MDA was higher than PEP method,but allele drop-out and pseudo allele were more frequently detected.Correct DNA typing rate of PEP is higher than MDA method,however,advantaged amplification of small fiagments DNA is more obvious.Conclusion MDA method is not suitable for the current STR typing.When the absolute amount of trace samples is quite small,we couldconsider using the PEP method to enhancethe sample quantity to meet the requirement of repeat testing.At the same time it could encounterthe failure of the large DNA fragments.

Identification of 5 Novel Y Chromosome STR Loci and Haplotype Distribution in Chinese Han Population (Guangzhou) / 中山大学学报(医学科学版)

[Objective] To screen and identify the new Y-STR loci from the Y chromosome and examine the polymorphism of these Y-STR loci. [Method] To seek and locate the position of 5 Y-STR loci, including DYS709, DYS720, DYS721, DYS722, and DYS723, and perform sequencing of these 5 Y-STR loci. Then to investigate the polymorphism in unrelated Chinese Han males. [Results] Five Y-STR loci were identified from Y chromosome sequence. By scrutinizing the physical position on Y chromosome of previously reported Y-STRs, we found that three loci were novel and two loci overlapped with two loci published only online. All loci could be male-specifically amplified with a product size ranging from 185 bp to 278 bp. After 108 males of the Chinese Han Population (Guangzhou) were examined, we found 5 DYS709, 11 DYS720 alleles, 4 DYS721 alleles, 6 DYS722 alleles, and 6 DYS723 alleles. A total of 95 haplotypes were identified, 84 of which were unique, and with a haplotype diversity of 0.997 2±0.001 2(HD±SE). [Conclusion] This set of Y-STRs can be used as Y chromosome genetic makers in related fields.

Study on typing of DNA extracted from urine and urine stains / 中国法医学杂志

Objective To investigate the extraction of DNA from urine and urine stains and typing.Methods DNA was extracted from urine and urine stains with Chelex-100 extraction method and QIAamp Mini Kit.STR loci were typed after amplification by PCR procedures with Profiler Plus Kit.Results STR loci could be well typed in DNA extracted from the urine,which was fresh or preserved properly for less than 12 hours.Satisfactory DNA typing could be made in 50% of the urine preserved for two days.No typing results were obtained in the samples kept for seven days or much longer time,and typing was rarely available using urine stains.Conclusion DNA extracted from the fresh urine can be typed,which may be used in forensic identification.

Study on DNA extracted from cigarette butts / 中国法医学杂志

Objective To study the DNA extraction and its typing in cigarette butts. Method Chelex 100 extraction method was used to extract DNA of 170 cigarette butts, STR loci were typed after PCR amplification by Profiler Plus kit. Results 21 cigarette butts from one volunteer have no results, the others were all obtained typing results. The samples which were added a little tobacco have no results. Sometimes DNA in sponge contacted with mouth was typed. The small fragment loci were typed in cigarette butts which had been reserved for six months. Conclusion Cigarette butt can be typed by DNA analysis, which is useful in forensic identification.