罪犯DNA数据库计算机检索系统

目的开发供输入、输出和检索罪犯ＤＮＡ遗传特征的计算机软件包。方法用中文ＶｉｓｕａｌＦｏｘｐｒｏ３０数据库开发软件编程,在建立罪犯ＤＮＡ数据库的基础上,根据ＳＴＲ基因型的类型,设计成显示、增加、编辑、查询、打印和退出等程序模块,并由主程序调用。结果提供一套在中文Ｗｉｎｄｏｗｓ９８环境支持下的、全屏幕菜单提示和操作的罪犯ＤＮＡ数据库计算机检索系统,它能有效地用于罪犯身份的识别     

An investigation of two methods of DNA recovery from fired and unfired 9 mm ammunition

Cartridge cases are often recovered from crime scenes involving firearms and, in the United Kingdom (where gun possession is strictly controlled), these are commonly from 9 mm calibre ammunition. The ability to obtain informative DNA profiles from touch DNA on recovered cartridges could have a significant impact on the investigation of that type of offence. However, this avenue may not be routinely considered as investigators in the UK have historically had a low expectation of obtaining useful DNA profiles. This stance may not be unreasonable given that (a) only trace amounts of DNA are likely to have been transferred onto the cartridge cases through handling; and (b) when the cartridge is spent, the potential deterioration of that DNA caused by the act of discharging the weapon.We introduce a novel semi-automatable method using direct lysis for the recovery of DNA from ammunition and compare it with a traditional double-swabbing method (using wet and dry swabs). DNA profiling of the DNA recovered using both methods was carried out using the ESI17 FAST STR system (Promega). This demonstrated a significant increase in DNA recovery using the direct lysis approach, and correspondingly improved STR results.We also investigated the effect on the recovery and profiling of DNA from fired, and unfired, 9 mm cartridges using the direct lysis technique. These results demonstrate that DNA suitable for STR analysis can still be recovered from fired ammunition with only slightly reduced yields compared to unfired ammunition. In these experiments, the handler of the ammunition was most commonly either the sole contributor or the major contributor to the recovered DNA profile.     

DNA isolation success rates from dried and fresh wood samples of selected 20 tropical wood tree species for possible consideration in forensic forestry

The successful isolation of DNA (Deoxyribonucleic Acid) is essential for the investigation process of forestry molecular genetics. Samples used are usually retrieved either from soft or juvenile plant organs because of their excellent DNA source. However, in certain cases, aforesaid samples are hard to obtain, as for forensic purposes. Alternatively, woods possess potential as alternative source of DNA whose extraction method has been developed with varying degrees of success. However, to date, effectiveness on tropical wood grown in Indonesia has not been widely reported. Therefore, objective of this study was to compare the results of DNA isolation of various dried and fresh wood samples by using two isolation methods: Cetyl Trimethyl Ammonium Bromide (CTAB) and Qiagen DNeasy Plant Mini Kit (QDPMK). Extraction results were visualized in agarose gels and quantified using Nanophotometer NP80 Implen which were then amplified using two universal primers: ITS and rbcL for detecting DNA signals. Extraction results from dried wood indicated no visualization in the gel, while fresh wood samples showed thick smeared bands on both extraction methods. Quantity test results denoted higher concentration in CTAB-extracted samples compared to samples extracted using QDPMK, in both types of samples, even though both resulted in optical density ratios outside the range of purity (λ260/280: 1,8–2,0 and λ260/230: 2,0, respectively). Success rates of ITS and rbcL primary amplification in dried wood samples were quite low yet outputs from the two methods did not differ significantly. Meanwhile, outcome of ITS and rbcL amplification on fresh wood samples had a fairly high success.     

Application of fragment analysis based on methylation status mobility difference to identify vaginal secretions

Identifying vaginal secretions attaching or adhering to a suspect’s belongings would be beneficial for reconstructing the events that have taken place during a sexual assault. The present study describes a novel approach to identify vaginal secretions by fragment analysis using capillary electrophoresis, based on the mobility differences of PCR amplicons from bisulfite-treated DNA depending on methylation status. We targeted three genome regions including each of three vaginal secretion-specific methylated CpG sites reported previously: cg25416153, cg09765089, and cg14991487. In all three genome regions, the amplicon peaks for methylated genomic DNA (gDNA) sequences were only detected in vaginal samples, whereas samples of other body fluids (blood, saliva, semen, and deposit on skin surface) only showed amplicon peaks for unmethylated gDNA sequences. In vaginal secretions, the methylation ratio of each of the three targeted regions between samples was variable, while the ratios at the three regions in each sample were similar. Furthermore, commercial vaginal epithelial cells were completely methylated at the three regions. Therefore, vaginal secretion-specific methylation may derive from vaginal epithelial cells present in the sample.In forensic cases with a limited amount of DNA, the reproducibility of a detected peak using the present method is not high due to degradation of DNA by bisulfite treatment and subsequent stochastic PCR bias. However, it was possible to detect peaks from methylated DNA sequences by performing PCR and capillary electrophoresis in triplicate after bisulfite treatment, even when bisulfite treatment was performed using 0.5 ng of gDNA from vaginal secretions. In addition, the level of methylation at each targeted region was found to be stable in vaginal secretions stored for 1 year at room temperature. Therefore, we conclude that detection of the visual peak from vaginal secretion-specific methylated DNA sequence is useful to prove the presence of vaginal secretions. This approach has the potential to analyze multiple marker regions simultaneously, and may provide a new multiplex assay to identify various body fluids.     

Forensic human identification: Investigation into tooth morphotype and DNA extraction methods from teeth

When a body is decomposed, hard tissues such as teeth may provide the only DNA source for human identification. There is currently no consensus as to the best DNA extraction method, and there is a lack of empirical data regarding tooth morphotype and condition that may impact DNA recovery. Therefore, this study sought to investigate which variables significantly improved DNA concentration, integrity and profiling success. A total of 52 human teeth were assessed, representing all tooth morphotypes from three deceased individuals. DNA was extracted using both the QIAamp® DNA Investigator Kit and the phenol-chloroform method. DNA concentration and degradation index were assessed using real time PCR, prior to conventional DNA profiling. Contrary to international guidelines promoting the use of molars, DNA profiling from molars was the least successful, with premolars, followed by canines, performing the best. The presence of fillings reduced the DNA quantity and quality obtained and may explain the poor performance of molars. DNA from the maxillae were significantly less degraded when the QIAamp® was used, although this did not influence DNA profiling success. A significant increase in DNA concentration, integrity and profiling success was observed in diseased teeth (periodontitis) compared to those without disease. This may be due to increased white blood cell presence at the site. There was no significant difference in DNA profiling success between the two DNA extraction methods. However, different teeth yielded failed DNA profiles for each extraction method, suggesting that repeated attempts, using alternative DNA extraction methods, is recommended. The recovery of additional DNA profiling information from degraded samples may help to ultimately reduce the burden of unidentified human remains.     

Collecting touch DNA from glass surfaces using different sampling solutions and volumes: Immediate and storage effects on genetic STR analysis

Touch DNA has become increasingly important evidence in todays' forensic casework. However, due to its invisible nature and typically minute amounts of DNA, the collection of biological material from touched objects remains a particular challenge that underscores the importance of the best collection methods for maximum recovery efficiency. So far, swabs moistened with water are often utilized in forensic crime scene investigations for touch DNA sampling, even though an aqueous solution provokes osmosis, endangering the cell's integrity. The aim of the research presented here was to systematically determine whether DNA recovery from touched glass items can be significantly increased by varying swabbing solutions and volumes compared with water-moistened swabs and dry swabbing. A second objective was to investigate the possible effects of storage of swab solutions prior to genetic analysis on DNA yield and profile quality when stored for 3 and 12 months, as is often the case with crime scene samples. Overall, the results indicate that adapting volumes of the sampling solutions had no significant effect on DNA yield, while the detergent-based solutions performed better than water and dry removal, with the SDS reagent yielding statistically significant results. Further, stored samples showed an increase in degradation indices for all solutions tested, but no deterioration in DNA content and profile quality, allowing for unrestricted processing of touch DNA samples stored for at least 12 months. One further finding was a strong intraindividual change in DNA amounts observed over the 23 deposition days which may be related to the donor's menstrual cycle.     

The effectiveness of various strategies to improve DNA analysis of formaldehyde-damaged tissues from embalmed cadavers for human identification purposes

Formalin-fixed tissues provide the medical and forensic communities with alternative and often last resort sources of DNA for identification or diagnostic purposes. The DNA in these samples can be highly degraded and chemically damaged, making downstream genotyping using short tandem repeats (STRs) challenging. Therefore, the use of alternative genetic markers, methods that pre-amplify the low amount of good quality DNA present, or methods that repair the damaged DNA template may provide more probative genetic information. This study investigated whether whole genome amplification (WGA) and DNA repair could improve STR typing of formaldehyde-damaged (FD) tissues from embalmed cadavers. Additionally, comparative genotyping success using bi-allelic markers, including INDELs and SNPs, was explored. Calculated random match probabilities (RMPs) using traditional STRs, INDEL markers, and two next generation sequencing (NGS) panels were compared across all samples. Overall, results showed that neither WGA nor DNA repair substantially improved STR success rates from formalin-fixed tissue samples. However, when DNA from FD samples was genotyped using INDEL and SNP-based panels, the RMP of each sample was markedly lower than the RMPs calculated from partial STR profiles. Therefore, the results of this study suggest that rather than attempting to improve the quantity and quality of severely damaged and degraded DNA prior to STR typing, a more productive approach may be to target smaller amplicons to provide more discriminatory DNA identifications. Furthermore, an NGS panel with less loci may yield better results when examining FD samples, due to more optimized chemistries that result in greater allelic balance and amplicon coverage.     

Investigating DNA barcodes of plants growing in some areas of Iran with high crime rate: Quercus brantii,Curpressus arizonica,Crataegus pentagyna,Ziziphus Spina-chtista,and Buxus hyrcana

According to criminal botany, the offender unknowingly carries plant samples from the crime scene. Therefore, studying the genetic data of plants native to the crime scene can solve many ambiguities in the criminal files. In this regard, the aim of this study was to investigate the genome of 5 endemic plants in some areas of Iran with high crime rate. Quercus brantii, Curpressus arizonica, Crataegus pentagyna, Ziziphus Spina-chtista, and Buxus hyrcana were assessed using 1 genetic fragment on plastid regions (trnH-psbA) as well as 1 gene on nuclear chromosome called ITS. The alignment of DNA sequences of trnH-psbA and ITS genes was done using BioEdit, Clustal X, and Muscle v4.0 software programs. The phylogenetic analysis was performed on aligned data using Maximum Parsimony (MP) and the Bayesian methods. The Splits Tree v.4.14.4 software program was used for phylogenetic network analysis. Finally, the data combinability test was conducted using the Incongruence Length Difference (ILD) test by PAUP* software program. All data from nrDNA ITS and trnH-psbA sequences were consistent with Information Compatibility Test (ICT) results. Moreover, the nrDNA ITS indicated more resolved relationship than trnH-psbA. The results from MP and Bayesian analyses did not differ significantly between singular and combined forms, except for a slight variance in confidence interval of branches. As the phylogenetic trees provide more thorough and deeper conception of species relations, it is hoped that they would be useful to illuminate some forensic gaps in regions with high crime rates enriched by these plants, not only in Iran, but also in all areas over the world with this vegetation.     

Sequence polymorphism in the coding region of mitochondrial genome encompassing position 8389–8865

Analysis of the polymorphic sequences in mitochondrial DNA (mtDNA) has been widely applied to forensic tests and anthropology studies. However, these polymorphic data in human have thus far been derived from the displacement-loop and intergenic regions only. Here, we report the identification of clustered polymorphic sites in the mitochondria coding region encompassing position 8389–8865. The DNA sequences of 119 unrelated Chinese were determined by PCR amplification and direct sequencing. The results showed that heteroplasmy was found in five individuals, 39 sites were noted in this 477 bp region, and 41 haplotypes were identified. The probability of identity and allelic diversity were estimated as 0.1265 and 0.8809, respectively. The results suggest that sequence polymorphism from position 8389–8865 in human mtDNA can be used as a marker for identity investigation.     

线粒体DNA分型技术

综述了线粒体DNA的遗传特性,线粒体DNA分型技术发展历程以及线粒体DNA分型技术相关质量控制、命名原则、异质型影响、结论诠释、数据统计,并展望了线粒体DNA分型技术的未来发展.