The appropriate use of subpopulation corrections for differences in endogamous communities

The bioluminescence response of two genetically modified (lux-marked) bacteria to potentially toxic compounds (PTCs) in stomach contents was monitored using an in vitro assay. Cells of Escherichia coli HB101 and Salmonella typhimurium both carrying the lux light producing gene on a plasmid (pUDC607) were added to stomach contents containing various concentrations of organic and inorganic compounds. There was some variability in the response of the two biosensors, but both were sensitive to the herbicides glyphosate, 2,4-dichlorophenoxyacetic acid (2,4-D), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T); pentachlorophenol (PCP), and inorganic poisons arsenic and mercury at a concentration range likely to be found in stomach contents samples submitted for toxicological analysis. This study demonstrates that biosensor bioassays could be a useful preliminary screening tool in forensic toxicology and that such a toxicological screening should include more than one test organism to maximise the number of PTC's detected. The probability of false positive results from samples containing compounds that may interfere with the assay such as over-the-counter (OTC) drugs and caffeine in tea and coffee was also investigated. Of the substances tested only coffee has the potential to cause false positive results.     

A method to enable forensic genetic genealogy investigations from DNA mixtures

The presence of more than one DNA contributor in an evidentiary sample may preclude attempts to use forensic genetic genealogy to develop an investigative lead. To address this issue, we developed a workflow for deconvolution of SNP mixtures into single source profiles that are suitable for matching against a genealogical database. Using the method, two-contributor DNA mixtures assayed using a commercial SNP typing kit can produce informative match results for both major and minor contributors.     

中国法庭科学DNA数据库

本文综述了中国法庭科学DNA数据库的建立和发展过程、DNA数据库结构、内容、特点、作用以及存在的问题、发展方向、展望,目的是为如何进一步建设好具有中国特色的DNA数据库提供借鉴。     

法医DNA检验的现状及发展

DNA检验自被作为证据引入法庭诉讼以来 ,随着科技的发展 ,其检验手段和方法不断更新和完善 ,经历了一个从小到大、从复杂到简单、从手工操作到仪器自动化的发展过程。本文综述了利用DNA推断年龄及DNA提取、检测等方面的新进展。     

The restrictase analysis of human DNA as a method for determining genetic sex in forensic biological expertise]

In this article phenomena related to sex heteromorphism of restrictase hydrolysates of DNA, isolated from objects of expert analysis was recommended for use. The performed investigations allow one to work out the system of discriminating sex of biological objects, based on restrictase analysis of human DNA and on registration of sex-specific restrictase fragments. Possibilities of method and its value for gene-identification expertise were illustrated using certain cases from expert practice.     

中国法医学会物证专业委员会法医DNA分析的若干建议

中国法医学会法医物证学专业委员会与国际法医遗传学会中文专委会于2006年10月在成都召开学术会议。我们的讨论强调有必要将国际法医遗传学会的信息及时传递到中国。因此,按照国际法医遗传学会的指南,我们推荐混合斑分析,法医DNA数据库及新遗传标记选择标准供同行参考。     

性染色体及线粒体DNA遗传标记的法医学应用

对性染色体及线粒体DNA的结构特征、遗传特征等相关基础知识及其遗传标记在法医学领域应用的研究进展等进行了综述,分析了上述各类遗传标记在法医学领域应用的利弊,以促进非常染色体DNA遗传标记在法医学实践中的应用。     

The use of wildcards in forensic DNA database searches

Forensic genetic databases contain millions of DNA profiles worldwide. An allelic drop-out at a heterozygous locus (two different alleles) erroneously results in an observed homozygous profile. To guard against this, wildcards are induced for homozygous profiles. The wildcard represents any allele including the observed allele.In this paper, theoretical expressions for the number of matching loci are derived, results shown from a Danish dataset with more than 50,000 DNA profiles and simulations used to link homozygosity with the drop-out probability, which best mimics wildcard matching.     

Can dentists recognize their own work? The forensic implications

After 10 months, 71.4% of a group of dental students were able to recognize amalgam restorations that they had placed in the mouths of manikins. After 24 months, 57.1% of the group were able to recognize their work again. In contrast, only 5.5% of a second group of students, who did not have the interim viewing at 10 months, could recognize their work at 24 months. These results suggest that, with time, dental operators lose the ability to recognize their work but that this ability is prolonged by interim observations of the work. This study underscores the need for dentists to chart and record accurately any artifacts introduced into the patient's mouth, as well as any features that would make the patient unique upon forensic examination.     

The recovery of pollen evidence from documents and its forensic implications

Three experiments were undertaken to establish the potential for forensic palynological analysis in cases of suspected document fraud. The first study tested 6 different types of paper and 9 different types of ink (n = 54) and it was established that the best retainer of particulates (in this case a proxy was used in the form of UV powder) was medium biro ink and Wove and Connoisseur paper. It was found that for the different paper types 42–52% of the particulates collected were found in the ink and thus both the paper and the ink are potentially valuable sources of trace evidence in a forensic investigation. The second study sought to address the differences in the spatial distribution of particulates on documents when writing took place before or after the paper was treated with UV particulates. Ninety-six observations were made for each piece of paper tested and it was found that when the writing took place after the particulates were applied to the paper; more particulates were retained on the paper in contrast to when the writing took place before the particulate treatment. The spatial distribution of particulates was also affected, with particulates being retained in the folds of the paper when the writing took place before particulate treatment in contrast to a more erratic pattern that emerged due to the pressure of the hand of the writer when the writing took place after the particulate treatment. The third study utilised lily (Lilium) pollen grains and the findings broadly concurred with the second study. The main difference identified was when the writing took place before the particulates were applied; when UV powder was used the particulates were retained in the folds of the paper whereas this pattern was not seen to the same degree when pollen grains were used due to their ‘stickier’ nature. Envelopes and the pen nibs were also found to be rich sources of pollen grains after the experiments were undertaken.These studies have implications for the application of forensic palynology in cases of suspected document fraud. Pollen grains may well be present, and their analysis has the potential to reveal not only the timing of the generation of the document, but the spatial trends revealed indicate that it may well be possible to establish the sequence of significant events for forensic reconstruction. As such forensic palynology is demonstrated to have great potential in aiding forensic investigations, and is as yet an under-utilised form of trace evidence.     

DNA甲基化在法医DNA分析中的应用

表观遗传学在生命的发生、发展过程中起着十分重要的作用。DNA甲基化作为表观遗传的一个重要方面,不仅参与多种基因的表达调控,与机体的发育、肿瘤发生等密切相关,而且具有可遗传性、相对稳定性、亲缘特异性、基因组中含量丰富等特点,已证实适用于法医DNA分析。本文对近年来DNA甲基化在印迹基因、同卵双生子鉴定、年龄、性别推断方面的研究与应用进行回顾与综述,以期为在法医学及相关领域中应用提供参考。     

国产法医DNA检验试剂耗材检测DNA标准品的准确性研究

目的利用法医DNA标准品对自主研发的法医DNA检验试剂耗材进行电泳检测准确性的实验考查。方法实验平台分为2个：平台1全部由美国AppliedBiosystems公司进口的3130xl遗传分析仪、16道电泳毛细管与甲酰胺、电泳缓冲液、凝胶构成;平台2由AppliedBiosystems公司进口的3130xl遗传分析仪、16道电泳毛细管与本实验室研发的甲酰胺、电泳缓冲液、凝胶构成。在实验平台上对allelicladder、内标等标准品以及阳性对照9947a的STR复合扩增产物进行电泳检测,利用GeneMapper软件对电泳结果进行分析。结果自主研发的法医DNA检验试剂耗材可与国外进口的3130xl遗传分析仪配套使用,构建的实验平台对法医DNA标准品的检测结果准确无误。结论自主研发的甲酰胺、电泳缓冲液、凝胶等法医DNA检验试剂耗材检测准确性达到了国外同类产品水平。     

Analysis of genetic diversity of the mitochondrial DNA in the forensic medical expert identification of individuals

Spectra of haplotype frequencies were studied for locuses of hypervariable segments 1 and 2 (HVS1 and HVS2), separately for each, and for linked segment HVS1-HVS2. The obtained data were used to determine the values and to evaluate comparatively the discriminating characteristics of the corresponding individualizing systems based on the typing of mtDNA. The system of typing, based on HVS2 (mv = 0.098), was found to possess the least discriminating potential; while the highest information rate is ensured in the analysis of HVS1 (m omega = 0.02) and in the joint analysis of HVS1 and HVS2 (mw = 0.007). The frequency rates of the key haplogroups were estimated within a random sampling of Russian citizens. A random population sampling of Russian citizens was shown not to differ essentially from an ethnically homogeneous population sampling of Russians selected with regard for a genetic diversity and for a spectrum of mitochondrial lines. The results point at the most rational algorithm of examinations in a forensic expert's analysis of mtDNA. The studied sampling can trigger the development of a referential data base designed for conducting, in the Russian Federation, the forensic-medical expert's examinations based on the mtDNA typing.     

法医DNA实践中的伦理问题

法医DNA始终在国际法医物证检验领域中占据核心地位,技术应用早已广泛成熟。近年来,诸多学者开始关注法医DNA伦理学方面的研究,目前该研究还处于初步探索阶段。本文是在伦理学已有学术基础上,从DNA数据库建设和亲子鉴定两个方面对法医DNA伦理学思想应用现状进行了初步探讨,并且参考国内外文献资料对伦理学思想在法医DNA实践中的应用原则进行了阐述,目的在于衡量法医DNA工作是否达到伦理方面的要求,其实践意义将在DNA数据库建设和亲子鉴定中起到重要作用。     

法医DNA分析的其他应用

综述了法医DNA的多种用途,如人死后根据体内DNA变化情况推断死后时间间隔,利用线粒体DNA4977bp的缺失以及端粒的长度推断年龄;利用昆虫mtDNA的细胞色素氧化酶亚基I进行昆虫种属鉴定,以帮助确定人的腐尸死亡时间;利用一些食血昆虫体内的人DNA帮助了解与案件的关系;利用DNA标记进行动物如犬、牛、马及猪等个体识别与亲子鉴定,解决因动物引起的纠纷,或者利用DNA分析嫌疑人周围的动物毛发、植物及土壤微生物等,确定嫌疑人与案件的关系。