Estimating Individual Contributions to Complex DNA SNP Mixtures.,

High‐throughput sequencing (HTS) of large panels of single nucleotide polymorphisms (SNPs) provides an alternative or complimentary approach to short tandem repeats (STRs) panels for the analysis of complex DNA mixture forensic samples. For STRs, methods to estimate individual contribution concentrations compare capillary electrophoresis peak heights, peak areas, or HTS allele read counts within a mixture. This article introduces three approaches (mean, median, and slope methods) for estimating individual DNA contributions to forensic mixtures for HTS/massively parallel sequencing (MPS) SNP panels. For SNPs, the major:minor allele ratios or counts, unique to each contributor, were compared to estimate contributor proportion within the mixture using the mean, median, and slope intercept for these alleles. The estimates for these three methods were typically within 5% of planned experimental contributions for defined mixtures.     

The CSI Effect and the impact of DNA evidence on mock jurors and jury deliberations

ABSTRACT

The present research examined the CSI Effect and the impact of DNA evidence on mock jurors and jury deliberations using a 3 (Crime Drama Viewing: low, moderate, high)?×?3 (Evidence: DNA innocent, DNA guilty, no DNA control) design. A sample of 178 jury-eligible college students read a case of breaking and entering. Pre-deliberation, some support for a CSI Effect was found with high viewers’ extent of guilt ratings significantly lower than moderate and low viewers’ in the no DNA control and the DNA innocent conditions. This effect was not present for verdicts. Contrary to a CSI Effect, crime drama viewing was not related to guilt judgments with incriminating DNA evidence. A content analysis of comments made during deliberations found little support for the CSI Effect entering the jury room. Specifically, CSI Effect predictions were not supported when examining the discussion of DNA evidence, expressing DNA opinions, or mentioning missing evidence. Overall, the limited CSI Effect found for individuals was attenuated during deliberation. The alarm raised over a possible CSI Effect influencing jury decision making may be unwarranted.     

基于分子克隆方法制备标准分子量片段混合物

目的制备标准分子量DNA片段混合物。方法选取pMD18-T载体部分序列作为插入片段,设计引物,制备包含不同大小的标准分子量片段的克隆。大量培养细菌提取质粒,用双酶切、连接荧光接头的方法制备不同大小的带有荧光的标准分子量片段,混合,纯化,最终获得标准分子量片段混合物(内标)。结果用分子克隆方法制备出具有实用性的标准分子量片段混合物,其单个标准分子量片段大小分别为80bp、124bp、194bp、224bp、254bp、304bp、349bp、399bp、424bp、454bp。并且这些标准分子量片段混合物可以准确地对DNATyper15试剂盒的扩增产物进行检测。结论应用该方法制备了能满足研究和实验室要求的标准分子量片段混合物,为DNA分子量标准物标准品的制作提供了一种新的方法。     

不同消毒方式对现场DNA检出影响研究

目的 探讨新型冠状病毒敏感的消毒方式对于常见现场生物物证如血、脱落细胞的检出影响,探索在疫情期间现场勘查、实验室检验及尸体解剖前后的合理消毒方式.方法 采用《消毒剂使用指南》推荐的几种不同浓度化学消毒剂和紫外线照射等方式,对常量的血、口腔拭子和稀释的血、唾液斑进行作用后的样本DNA检出情况进行对比.结果 常用消毒方式对...     

紫外光谱法测定尿液中安眠类药物的含量

本文应用紫外可见光谱法研究了苯并二氮　类、吩噻嗪类药物的测定方法,分析的药物在０μｇ·ｍｌ－１～２０μｇ·ｍｌ－１内有良好的线性关系。提出了利用固相萃取技术测定尿液中药物的简便、快速的方法,测定尿液中药物的检出限为１．０μｇ·ｍｌ－１,回收率为７７．５％－１０１．２％。     

DNA侦查技术的应用与前景

DNA侦查技术克服了以往遗传标记检测的种种缺陷以及指纹技术的一些局限 ,实现了物证检验从否定到认定的飞跃。目前DNA侦查技术正在走向更广阔、更深入的领域 ,出现了具有良好应用前景的一些新技术 ;许多国家均投资建立国家DNA犯罪数据库。我国的DNA犯罪数据库也在加紧建设中。从目前我国的有关情况看 ,建立DNA技术标准化和质量控制体系 ,已成为我国法庭科学亟待解决的问题。然而 ,DNA鉴定的不断完善 ,还有赖于人类基因组计划。     

新型手印提取器的研究

现场勘查中,技术人员对用粉末刷显的手印、灰尘加层手印拍照提取后,再用新型手印提取器提取效果更好。手印提取器使胶带与客体接触面积变小、压力均匀,从而避免在提取过程中产生气泡;同时,胶带具有粘性的一面与另一胶带紧密相粘,通过转动,能制成透明的手印检材,可直接通过印相放大、复印,或通过反差较大的衬底做背景进行比对鉴定。实践证明,运用手印提取器提取的手印具有高质量、手印特征反映好、保存时间长,而且在使用中方便简捷,提取速度快等优点。     

Cloud point extraction coupled with back extraction: a green methodology in analytical chemistry

Recently, cloud point extraction (CPE) coupled with back extraction (BE) has been suggested as a promising alternative to liquid-liquid extraction. In CPE, non-ionic surfactants in aqueous solutions form micelles and the solution becomes turbid when heated to the cloud point temperature. Microwave- or ultrasonic-assisted BE can be performed after CPE and before injection of the sample for instrumental analysis by ultraviolet-visible spectroscopy, high-performance liquid chromatography, gas chromatography, gas chromatography-mass spectrometry, or liquid chromatography-mass spectrometry. This article reviews selected published scientific research on the application of CPE-BE to the determination of alkaloids, drugs and organophosphorus compounds from several complex matrices. This method could be scaled-up for use in forensic science.     

Molecular Identification of Necrophagous Dermestes Species in South Korea Using Cytochrome c Oxidase Subunit I Nucleotide Sequences (Genus Dermestes)

Species identification of necrophagous insects found on a dead body is an essential key in applying medicolegal entomology to the estimation of postmortem interval (PMI). Due to limited morphological identification of insect evidence, several studies have identified species using molecular information such as DNA markers. While considerable cytochrome c oxidase subunit I (COI) gene sequence data of necrophagous fly species have been collected and annotated, those of necrophagous beetle species have not. Since necrophagous beetles such as Dermestes species have a larval period longer than that of flies, beetles are useful in even the late decomposition phase in estimating minimum PMI. To obtain the full-length COI gene sequences of six Dermestes species collected from South Korea, we designed primers for polymerase chain reaction amplification and sequencing. The obtained full COI nucleotide sequences were used for performing phylogenic analysis and comparison with previously reported sequences. The results demonstrated that the COI gene sequences could be used to identify forensically important Dermestes species in South Korea.     

Simplified Direct PCR Method for Reference Buccal Samples Using a Non-FTA Card by Omitting the Pretreatment Step

When using non-FTA cards in commercial multiplex STR kits for direct PCR, pretreatment steps with specific buffers are recommended. Here, we designed a rapid direct PCR method utilizing a non-FTA card, Oral Cell Sampling Kit, by omitting the pretreatment step involving Prep-n-Go™ Buffer, and it showed compatibility with the GlobalFiler™ Express PCR Amplification Kit, GlobalFiler™ PCR Amplification Kit, and PowerPlex^® Fusion system. To optimize the PCR conditions, we tested the method with different final PCR volumes and cycles. Finally, we conducted a performance test using 50 Korean buccal samples and confirmed the high performance of the method, detecting more than 90% of the samples with full profiles when using GlobalFiler™ PCR Amplification Kit and PowerPlex^® Fusion system at 29 cycles in a 10 μL final PCR volume. Thus, we report a simple direct PCR set-up to analyze reference samples collected using a non-FTA card manufactured in Korea.