New optimized DNA extraction protocol for fingerprints deposited on a special self-adhesive security seal and other latent samples used for human identification

Abstract: Obtaining complete short tandem repeat (STR) profiles from fingerprints containing minimal amounts of DNA, using standard extraction techniques, can be difficult. The aim of this study was to evaluate a new kit, Fingerprint DNA Finder (FDF Kit), recently launched for the extraction of DNA and STR profiling from fingerprints placed on a special device known as Self‐Adhesive Security Seal Sticker^® and other latent fingerprints on forensic evidentiary material like metallic guns. The DNA extraction system is based on a reversal of the silica principle, and all the potential inhibiting substances are retained on the surface of a special adsorbent, while nucleic acids are not bound and remain in solution dramatically improving DNA recovery. DNA yield was quite variable among the samples tested, rendering in most of the cases (>90%) complete STR profiles, free of PCR inhibitors, and devoid of artifacts. Even samples with DNA amount below 100 pg could be successfully analyzed.     

Detection of genotype recycling fraud in U.S. immigrants

Abstract: Relationship testing laboratories provide genetic evidence to support or refute claims of kinship between U.S. citizen petitioners and potential immigrant beneficiaries. One female beneficiary presented a male amelogenin type and alleles at 15 autosomal loci that were identical to an alleged brother’s. Laboratory records showed that her alleged father had petitioned to have 15 children emigrate from Ghana. The petitioner’s 15 paternity indices exceeded 10⁵, but the children shared only four short tandem repeat (STR) profiles, suggesting fraudulent reuse of genotypes in this alleged pedigree (AP). To determine the extent of this “genotype recycling,” I examined the laboratory’s 555 APs from Ghana and 532 control APs from Nigeria. Seventeen Ghanaian APs (3.1%) but no Nigerian APs showed genotype recycling. Of 90 tested people in the 17 APs, 56 shared identical STR profiles with others in their AP. Of these 56 people, 10 were petitioners with unexpectedly high parentage indices. Seven of 56 had amelogenin types that disagreed with their declared genders. Database searches for identical multilocus genotypes in allegedly different people would best detect this fraud.     

Development of a DNA-based macroarray for the detection and identification of Amanita species

A DNA-based macroarray was designed to quickly and accurately identify certain Amanita mushroom specimens at the species level. The macroarray included probes for Amanita phalloides and Amanita ocreata, toxic species responsible for most mushroom poisonings, and Amanita lanei and Amanita velosa, edible species sometimes confused with toxic species, based on sequences of the highly variable internal transcribed spacer (ITS) region of rDNA. A cryptic species related to A. ocreata and one related to A. lanei, identifiable by ITS sequences, were also included. Specific multiple oligonucleotide probes were spotted onto nylon membranes and the optimal hybridization temperatures were determined. The Amanita DNA array was highly specific, sensitive (0.5 ng DNA/μL and higher were detected), and reproducible. In two case studies, the method proved useful when only small amounts of mushroom tissue remained after a suspected poisoning. An identification could be completed in 12 h.     

激光显微捕获技术用于尿液脱落细胞DNA检测

目的采用激光显微捕获技术（LCM）捕获尿液脱落细胞,并进行STR分型。方法收集10份健康成人尿液样本,根据储存时间分组,其中新鲜尿液组（≤24h）分别采用Chelex-100及LCM联合DNA IQTM提取法提取DNA,储存尿液组（〉24h）再分为4℃组和室温组,分别在4～30d内不同时间点采用LCM联合DNA IQTM提取法提取DNA;各组提取的模板DNA进行扩增及SRT分型检验。结果新鲜尿液组采用LCM联合DNA IQTM提取法提取DNA,所有样本均可检出全部基因座（16个）,采用Chelex-100法则在部分基因座上出现等位基因丢失、非特异性扩增、峰值低等现象;4℃储存10d和室温储存4d以内的尿液经检验可明确判读12个以上基因座,4℃20～30d及室温7d,可检出7个以上基因座。结论 LCM技术可用于尿液检材的DNA分型检验,且检材应尽可能4℃保存并尽快检验。     

中国DNA数据库建设应用技术现状及发展趋势

中国的法庭科学DNA数据库建设历经10年,在应用中取得了显著成果.随着DNA分析技术的进步,DNA数据库更加完善,DNA信息作用更加突显.本文综述了中国DNA数据库的规划与建设,DNA数据库建设中的应用技术,以及DNA数据库建设应用技术发展趋势,为完善DNA数据库建设提供借鉴.     

生物检材DNA碱性裂解提取法的优化与改良

目的通过对DNA碱性裂解提取法进行优化和改进,建立一种操作更简便、检验快速、结果更可靠的生物检材DNA提取方法。方法以抗凝血作为检验样本,通过改变提取试剂的浓度、pH值、保存时间及孵化样本的温度、时间等条件,观测对检验结果峰值的影响,以确定提取试剂最佳条件,DNA提取物最佳保存条件。通过用改良后的碱性裂解法及Chelex100法同时提取不同量的抗凝血样本、各类法医生物检材,用不同厂家的DNA试剂盒扩增,对碱性裂解法的灵敏度、适应性和适用性进行评估。结果改良后的碱性裂解法只需将生物检材用NaOH（0.25mol/L）99℃孵化8min,振荡后加入TrisHCl（0.05mol/L,pH=6.5）中和液,离心后直接扩增检测。DNA提取物于-20℃冰箱可长期保存。对于毛发及精斑类检材优于Chelex100法。DNA提取物适用于现有各种DNA试剂盒扩增检测,其灵敏度与Chelex100法相似。结论改良后的碱性裂解法,操作简便、检验快速、结果可靠,可适合于法庭科学的检案与建库。     

The CSI effect and the Canadian and the Australian Jury

Television shows, such as CBS's CSI and its spin-offs CSI: Miami; CSI: Las Vegas; and CSI: New York, have sparked the imagination of thousands of viewers who want to become forensic scientists. The shows' fictional portrayals of crime scene investigations have prompted fears that jurors will demand DNA and other forensic evidence before they will convict, and have unrealistic expectations of that evidence. This has been dubbed the "CSI effect." This phenomenon was explored using results from a Canadian study based on 605 surveys of Canadian college students who would be considered jury-eligible and Australian quantitative and qualitative findings from a study that surveyed and interviewed real posttrial jurors. Information about the way jurors deal with forensic evidence in the context of other evidence and feedback about the way in which understanding such evidence could be increased were gained from both these studies. The comparison provides insights into the knowledge base of jurors, permitting adaptation of methods of presenting forensic information by lawyers and experts in court, based on evidence rather than folklore. While the Canadian juror data showed statistically significant findings that jurors are clearly influenced in their treatment of some forensic evidence by their television-viewing habits, reassuringly, no support was found in either study for the operation of a detrimental CSI effect as defined above. In the Australian study, in fact, support was found for the proposition that jurors assess forensic evidence in a balanced and thoughtful manner.     

Y-chromosome STR haplotypes in a sample from São Paulo State, southeastern Brazil

Population: Unrelated males from the S?o Paulo State, Brazil (n=617).     

Population data for a novel, highly discriminating tetra-local Y-chromosome short tandem repeat: DYS503

Population: Population samples for gene diversity studies were obtained from the Virginia Division of Forensic Science (bloodstains), Richmond, VA. Ninety-eight Caucasian and 100 African American samples were included in this study.