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.     

法医学难检样品的处理及检测方法研究

在法医物证检验中常常会遇到一些量微而保存条件差的检材,这类检材的成功分析对案件的调查和侦破常起着至关重要的作用,其关键在于能否正确提取和处理检材、并采用适当的分析方法进行检测.笔者结合多年的物证检验经验和研究,综述了常见的牙齿、烟头、毛发、微量血痕等检材的有效处理方法.     

大鼠肾细胞DNA含量与死亡时间关系的图像分析

运用计算机图像分析技术,对大鼠死后肾细胞DNA的变化进行观测,以寻找一种客观、量化的推断早期死亡时间的标准.实验选择15只大鼠,处死后,在24小时内每隔1小时取肾组织进行细胞学涂片,福尔马林液固定,Feulgen染色,自动图象分析仪测量,所得数据进行统计学分析处理.实验结果证明大鼠的早期死亡时间与肾细胞核DNA降解速率呈线性关系,其中积分光密度、平均灰度、异形指数提示此方法有可能作为辅助手段,使死亡时间推断更为精确.     

一种改良的骨组织DNA提取方法

骨组织耐腐败,当其他软组织已完全腐败后,只能用骨组织进行种属鉴定,性别鉴定和个人识别.骨组织DNA提取是骨组织DNA分析的关键.作者曾用多种方法提取过骨组织DNA,本文报道一种改良的骨组织DNA提取方法.     

大鼠脑细胞DNA含量与死亡时间关系的图像分析

运用计算机图像分析技术 ,对大鼠死后脑细胞DNA的变化进行观测 ,以寻找一种客观、量化的推断早期死亡时间的标准。实验选择 1 5只大鼠。处死后 ,在 2 4h内每隔 1h分别取脑细胞进行细胞学涂片、福尔马林液固定、Feulgen染色、自动图象分析仪测量、统计学处理。结果显示 :大鼠的早期死亡时间与其脑细胞DNA降解速率呈线性关系 ,其中积分光密度 (IOD)、平均灰度 (AG)、异形指数 (ID)提示本法有可能作为精确推断死亡时间 (PMI)的辅助手段。     

Quantifiler observations of relevance to forensic casework

The Quantifiler (QF) kit is regularly used by forensic scientists for DNA quantitation. We performed in-house validation studies which revealed some interesting observations. The QF standard displayed a two-fold difference between two different lot numbers which suggests that every standard should be tested prior to use. The Promega K562 DNA standard works well with the QF kit. c. 41% of samples that inhibited the internal PCR control (IPC) system within the QF kit still produced good Profiler Plus reactions. QIAquick was effective at removing inhibitors. The presence of dyes within casework samples were observed not to inhibit QF amplifications. Template DNA greater than 100 ng/muL appeared to inhibit the IPC. Close to identical concentration results were obtained when alternative analysis settings were used. These validation findings will assist DNA processes involved in forensic casework.     

Direct STR amplification from whole blood and blood- or saliva-spotted FTA without DNA purification

The DNA purification step has been thought to be essential for typing of STR DNA. However, this process is time-consuming, and there is a risk of unexpected cross-contamination during purification. We report a new method for direct short tandem repeat (STR) amplification using a newly developed direct PCR buffer, AnyDirect, which can amplify STR loci from whole blood and blood- or saliva-spotted FTA cards without DNA purification. The autosomal and Y chromosomal STR loci were analyzed for whole blood and blood or saliva spots of random individuals, followed by comparison of the results with those of corresponding purified DNA. The results from whole blood and blood spots showed perfect concordance with those from purified DNA without allele or locus drop-out. However, in the case of saliva spots, no amplification or locus drop-out was observed in some of the samples, which offers a topic for further study. Additionally, some commercial hot-start DNA polymerases other than AmpliTaq Gold DNA polymerase were also found to be compatible with this buffer system. Therefore, this direct PCR buffer was demonstrated to be useful for fast forensic DNA analysis or criminal DNA databases for which there is no need to store DNA samples.     

The ultrastructure of tissue attached to telogen hair roots

Most tissues encountered in forensic biology laboratories have been previously characterized with electron microscopy due to their medical importance. Anagen hair root cells, epithelial cells, erythrocytes, neutrophils, osteocytes, and spermatozoa have received considerable research attention at the ultrastructural level. There is no literature indicating that cells attached to removed telogen hair roots have been characterized with transmission electron microscopy. Nonetheless, telogen hairs are a frequent submission item to forensic laboratories for DNA typing. The amount of tissue attached to a telogen hair root usually determines whether that hair is suitable for nuclear DNA typing methods or mitochondrial DNA typing methods. This study used transmission and scanning electron microscopy to characterize the tissues found in three commonly occurring telogen hair root forms. The tissues were found to consist of keratinized remnant follicle, nonnucleated epithelial cells, nucleated epithelial cells, and trichilemmal keratin. These findings were consistent with the known principles of hair follicle regression. The recognition of the root structures that contain these specific tissue types may assist in the DNA typing of telogen hairs inasmuch as the quality of tissue present may be more important than the amounts of tissue present.