法医遗传学研究和鉴定中的伦理问题

法医遗传学主要以人体生物检材为对象,通过检测遗传信息解决与法律相关的生物检材鉴识问题,为侦查提供线索,为审判提供证据,往往涉及到众多伦理问题。本文提出伦理学在法医遗传学研究和鉴定中的应用基本原则,并对检材/样本收集、法医DNA表型分析、法医遗传系谱学分析、法医DNA数据库建设和应用、亲子鉴定和亲缘鉴定、法医遗传学科研数据交流和共享等方面涉及的伦理问题进行了分析,提示法医遗传学从业人员在研究和鉴定中要充分考虑伦理问题,建议有关部门制定法医遗传学具体的伦理要求,建立伦理审查制度,加强从业人员伦理学培训。     

案例教学法在法医病理学国家精品课程教学中的应用

精品课程是国家教育部关于高等学校教学质量和教学改革工程的重要内容,是衡量高等学校教学质量和人才培养质量的标杆之一,精品课程建设在高等医学教学工作中具有重要的地位。法医病理学是一门应用学科,是法医学专业的主干课程,法医病理学教材中部分内容单调、枯燥,在教学中紧靠教材上知识,很难调动起学生的热情。传统教学方法虽然可以系统讲解基本理论知识,但属灌输式教学,不利于发挥学生的主观能动性和培养学生的思维。采用案例教学法,以学生为中心,理论联系实践,提高学生分析问题和解决问题的能力,有组于学生实践能力的培养,提高了法医病理学教学质量,值得推广及应用。     

全基因组扩增技术及其在法医个体识别中的应用

全基因组扩增(Whole genome amplification,WGA)技术是一种对全部基因组序列进行非选择性扩增的技术。近几年来,对WGA技术扩增痕量DNA检材的研究日渐深入,这些研究可望用于刑案现场采集到的痕量DNA样品的扩增,为法医个体识别提供足量的DNA模板。然而,对实际案件中复杂检材的扩增偏差问题一直困扰着法医工作者,寻求一个低扩增偏差、高扩增产率的WGA技术是法医工作者的主要目标。文章综述了WGA技术在法医个体识别中的研究进展及应用前景,为法医解决扩增偏差问题提供参考。     

滚环扩增技术的原理及其应用的研究

滚环扩增是近年来发展起来的一种恒温核酸扩增方法。这种方法不仅可以直接扩增DNA和RNA,还可以实现对靶核酸的信号放大,灵敏度达到一个拷贝的核酸分子,因此,RCA技术在全基因组扩增、单核苷酸多态性、DNA芯片、蛋白质芯片等方面检测中具有很大的应用价值和潜力。     

DNA分型技术在法医物证学中的技术应用

本文主要就DNA检验中的STR分型技术的法医物证学技术应用做一分析和探讨。     

脑血管畸形致猝死的法医病理研究

目的:分析脑血管畸形致猝死的法医病理理论。方法:选择法医学工作中31例脑血管畸形致猝死病例作为研究对象,分析病例的猝死原因以及病理类型等情况。结果:31例中有25例有明显的外伤史,其中大部分为斗殴造成的外伤,脑血管破裂出血之后导致死亡。脑动脉或静脉畸形是最为常见的脑血管畸形病理类型,28例患者为此类病理类型,畸形的主要发生部位有脑底部、脑室、蛛网膜下腔和脑干;最为常见的出血类型是蛛网膜下腔出血,占14例。结论:就法医病理学研究而言,脑血管畸形致猝死的鉴定具有一定的难度,再结合法医病理学特点的同时可以联合脑血管造影、磁共振检查等措施,确保得到科学、准确的结论。     

粪便RNA的检测在大肠癌早期诊断中的应用

大肠癌是胃肠道恶性肿瘤之一,在我国大肠癌的发病率和死亡率呈上升趋势。由于死亡率与大肠癌的诊断时间密切相关,因此早期诊断大肠癌尤为重要。但是目前临床常规诊断方法存在一定的局限性,难以实现大肠癌的早期诊断。粪便RNA检测技术是近年来发展的基于分子水平的早期无创检测大肠癌的技术,与常规检测技术包括结肠镜检测、大便隐血检测和粪便DNA突变检测相比,粪便RNA检测具有成本低和灵敏度高等优点,并可同时分析多种基因表达量和动态监测肿瘤进展。文章介绍了粪便RNA检测的可行性,系统阐述了用于粪便RNA检测的特异性基因、粪便RNA的提取方法和粪便RNA的检测技术,并对粪便RNA检测技术在大肠癌早期诊断中的进一步应用进行了展望。     

定量PCR和逆转录PCR在病毒学的应用

<正>在过去几年内,分子杂交法由于其技术多样性和高度特异性已被广泛用于基础和应用病毒学中。采用这些技术,可以在分子水平上直接进行临床样品的DNA和RNA病毒的检测、病毒基因体外-体内特异性转录活性的分析、以及病毒-宿主相互关系的研究。然而,尽管这些方法对多种检测是很有效的,但只有PCR扩增技术的发展和最佳化才明显提     

基因芯片技术在检测肠道致病菌方面的应用

基因芯片技术具有高通量、自动化、快速检测等特点,因此被广泛地应用于各种研究领域,如细菌分子流行病学、细菌基因鉴定、致病分子机理、基因突变及多态性分析、表达谱分析、DNA测序和药物筛选等。现介绍基因芯片检测肠道致病菌方面的国外研究进展,基因芯片应用于检测肠道致病菌的3个方面:结合多重PCR对致病菌的毒力因子或者特异性基因进行鉴定;直接检测细菌的DNA或者RNA;以致病细菌核糖体RNA作为检测的靶基因同时检测多种肠道致病菌。由于其检测的高效率,该技术要优于其他分子生物学检测方法。基因芯片技术在肠道致病菌检测中有着巨大的应用价值,具有广阔的应用前景。     

转录介导的扩增技术及其在诊断中的应用

转录介导的扩增技术可以RNA或DNA为模板,利用RNA聚合酶和逆转录酶在约42°C等温反应条件下进行扩增,产物为RNA。该技术在每一循环可产生模板的100～1000个拷贝转录本,15～30 min可将模板扩增约1010倍,在人类白细胞抗原等位基因分型、细菌和病毒的快速检测中发挥了重要作用。     

An mRNA and DNA co-isolation method for forensic casework samples

RNA analysis is expected to play an increasingly important role in the area of biomolecular forensic analysis. For example, mRNA expression analysis performed on a total RNA sample isolated from a biological stain may be used to identify the nature of the tissue(s) comprising the stain. Many of the physiological stains encountered at crime scenes involve heterogeneous mixtures of different body fluids (e.g., semen and saliva, semen and vaginal secretions). Separate sampling of these mixed stains from different "geographical" locations of the stains to isolate DNA and RNA could result in a misleading estimate of the ratio of the body fluids present and, in extreme cases, even fail to detect one of the contributors. Thus, a prerequisite for the use of mRNA expression profiling in routine forensic analysis is the ability to co-extract DNA and RNA from the same stain. This article describes an optimized method that was specifically developed to co-extract mRNA and DNA from the same physiological stain and that appears to be sufficiently sensitive and robust for routine forensic use.     

Vitreous humour as a potential DNA source for postmortem human identification

PURPOSE: The aim of this study was the assessment of vitreous humor as a potential DNA for forensic human postmortem identification. MATERIAL AND METHODS: Vitreous humor samples were collected using two alternative approaches from 25 corpses of either sex during autopsies. DNA was extracted by standard organic method. Recovered DNA was quantitiated fluorometrically. AmpFlSTR SGM Plus kit and ABI 310 Genetic Analyzer (Applera) were used to obtain genetic profiles. RESULTS: Different DNA yields were quantitated in vitreous body depending on cause of death and sampling approach. CONCLUSION: Vitreous humor is a potential DNA for forensic human postmortem identification depending on a sampling method used.     

Microbial traces and their role in forensic science

Forensic microbiology, also known as the microbiology of death, is an emerging branch of science that is still underused in criminal investigations. Some of the cases might be difficult to solve with commonly used forensic methods, and then they become an operational field for microbiological and mycological analyses. The aim of our review is to present significant achievements of selected studies on the thanatomicrobiome (micro-organisms found in the body, organs and fluids after death) and epinecrotic community (micro-organisms found on decaying corpses) that can be used in forensic sciences. Research carried out as a part of the forensic microbiology deals with the thanatomicrobiome and the necrobiome—communities of micro-organisms that live inside and outside of a putrefying corpse. Change of species composition observed in each community is a valuable feature that gives a lot of information related to the crime. It is mainly used in the estimation of post-mortem interval (PMI). In some criminal investigations, such noticeable changes in the microbiome and mycobiome can determine the cause or the actual place of death. The microbial traces found at the crime scene can also provide clear evidence of guilt. Nowadays, identification of micro-organisms isolated from the body or environment is based on metagenome analysis and 16S rRNA gene amplicon-based sequencing for bacteria and ITS rRNA gene amplicon-based sequencing for fungi. Cultivation methods are still in use and seem to be more accurate; however, they require much more time to achieve a final result, which is an unwanted feature in any criminal investigation.     

Role of short tandem repeat DNA in forensic casework in the UK--past, present, and future perspectives

The analysis of short tandem repeat (STR) DNA sequences is of fundamental importance to forensic science because they have become the recognized standard in constructing national public databases. Consequently, considerable effort has been expended in developing multiplexed (one tube) reactions that analyze several loci in combination. The implementation of STRs in casework cannot take place without a full understanding of the systems used. The purpose of validation is to characterize multiplexes when one is challenged with forensic samples. For example, mixtures are often encountered that may be particularly difficult to interpret against a background of allelic artifacts. By increasing the number of PCR amplification cycles, it is possible to dramatically boost the sensitivity of the system so that just a handful of cells may be successfully analyzed. However, interpretation is much more complex because the origin of DNA profiles may be less certain and complicated by issues such as contamination, the potential for innocent transfer and a predominance of mixtures. This review provides a brief historical background of the development of STRs in forensic casework that culminated in the creation of national DNA databases. The development of guidelines to interpret complex DNA profiles, such as mixtures, is outlined. Finally, the recent innovation of low copy number DNA profiling is explained along with the special considerations needed to report in court.     

哺乳动物单细胞研究技术的现状与未来

近年来,生命科学和医学的基础研究已深入到单细胞阶段。单细胞研究为揭示生命活动的基本规律、探索细胞异质性、提高对疾病发病机制的认识等提供了重要的线索和依据,同时,单细胞技术已被应用于日常实践中,如法医学和临床生殖医学。单细胞研究中使用的技术也在不断变化,并越来越复杂。文中主要介绍单细胞分离技术,包括手工挑取、激光捕获显微切割和微流控技术,以及单细胞中DNA、RNA和蛋白质分析方法的各种技术。此外,文中总结了近年来生命科学和医学领域的主要单细胞研究成果,讨论了单细胞相关技术和研究的不足,并介绍了其未来的发展方向。     

Paper-based archiving of mammalian and plant samples for RNA analysis

The ability to archive biological samples for subsequent nucleic acid analysis is essential for tissue specimens and forensic samples. FTA Card is a chemically treated filter paper designed for the collection and room temperature storage of biological samples for subsequent DNA analysis. Its usefulness for the preservation of biological samples for subsequent RNA analysis was tested. Here, we demonstrate that RNA in biological samples stored on FTA Cards is stable and can be used successfully for RT-PCR and northern blot analysis. RNA stability depends on the storage temperature and the type of biological specimen. RNA in mammalian cells stored on FTA Cards is stable for over one year at temperatures at or below -20 degrees C and for two to three months in samples stored at room temperature. For plant leaf, longer storage times (> 5 days) require temperatures at or below -70 degrees C following sample application. FTA Cards may constitute a method not only for convenient collection and storage of biological samples but also for rapid RT-PCR analysis of tissue and cell samples.     

Microbial Degradation of Forensic Samples of Biological Origin: Potential Threat to Human DNA Typing

Forensic biology is a sub-discipline of biological science with an amalgam of other branches of science used in the criminal justice system. Any nucleated cell/tissue harbouring DNA, either live or dead, can be used as forensic exhibits, a source of investigation through DNA typing. These biological materials of human origin are rich source of proteins, carbohydrates, lipids, trace elements as well as water and, thus, provide a virtuous milieu for the growth of microbes. The obstinate microbial growth augments the degradation process and is amplified with the passage of time and improper storage of the biological materials. Degradation of these biological materials carriages a huge challenge in the downstream processes of forensic DNA typing technique, such as short tandem repeats (STR) DNA typing. Microbial degradation yields improper or no PCR amplification, heterozygous peak imbalance, DNA contamination from non-human sources, degradation of DNA by microbial by-products, etc. Consequently, the most precise STR DNA typing technique is nullified and definite opinion can be hardly given with degraded forensic exhibits. Thus, suitable precautionary measures should be taken for proper storage and processing of the biological exhibits to minimize their decaying process by micro-organisms.     

Random Whole Metagenomic Sequencing for Forensic Discrimination of Soils

Here we assess the ability of random whole metagenomic sequencing approaches to discriminate between similar soils from two geographically distinct urban sites for application in forensic science. Repeat samples from two parklands in residential areas separated by approximately 3 km were collected and the DNA was extracted. Shotgun, whole genome amplification (WGA) and single arbitrarily primed DNA amplification (AP-PCR) based sequencing techniques were then used to generate soil metagenomic profiles. Full and subsampled metagenomic datasets were then annotated against M5NR/M5RNA (taxonomic classification) and SEED Subsystems (metabolic classification) databases. Further comparative analyses were performed using a number of statistical tools including: hierarchical agglomerative clustering (CLUSTER); similarity profile analysis (SIMPROF); non-metric multidimensional scaling (NMDS); and canonical analysis of principal coordinates (CAP) at all major levels of taxonomic and metabolic classification. Our data showed that shotgun and WGA-based approaches generated highly similar metagenomic profiles for the soil samples such that the soil samples could not be distinguished accurately. An AP-PCR based approach was shown to be successful at obtaining reproducible site-specific metagenomic DNA profiles, which in turn were employed for successful discrimination of visually similar soil samples collected from two different locations.     

Forensic implication of cadaveric behaviors of the Japanese pavement ant (Tetramorium tsushimae Emery) attending to rabbit cadavers

It is noticed by some researchers that ants may cause some forensic confusion in understanding death scenes. In the aspect of relationship between the ant‐animal decomposition, we observed the behavior of ants congregating on dead animals. Amongst various species of ants visiting dead rabbits, Tetramorium tsushimae Emery was noticeable in producing scratched scars, mounds, and nests around dead rabbits and covering them with soils. The behaviors are likely to interfere or to disturb the usual process of decomposition succession lead by maggots. We discussed that a series of cadaveric behaviors of T. tsushimae may be used as a potential forensic hint not to misunderstand death scenes disturbed by the species.