Simultaneous Identification of Four “Legal High” Plant Species in a Multiplex PCR High‐Resolution Melt Assay,

The international prevalence of “legal high” drugs necessitates the development of a method for their detection and identification. Herein, we describe the development and validation of a tetraplex multiplex real‐time polymerase chain reaction (PCR) assay used to simultaneously identify morning glory, jimson weed, Hawaiian woodrose, and marijuana detected by high‐resolution melt using LCGreen Plus^®. The PCR assay was evaluated based on the following: (i) specificity and selectivity—primers were tested on DNA extracted from 30 species and simulated forensic samples, (ii) sensitivity—serial dilutions of the target DNA were prepared, and (iii) reproducibility and reliability—sample replicates were tested and remelted on different days. The assay is ideal for cases in which inexpensive assays are needed to quickly detect and identify trace biological material present on drug paraphernalia that is too compromised for botanical microscopic identification and for which analysts are unfamiliar with the morphology of the emerging “legal high” species.     

Development of a PCR High‐Resolution Melt Assay for Artemisia absinthium (Wormwood) and a Triplex Assay with Two Additional “Unregulated Legal High” Species Datura stramonium (Jimson Weed) and Merremia tuberosa (Hawaiian Woodrose),

Artemisia absinthium (wormwood), a common ingredient in absinthe, contains the compound thujone, which is unregulated by the U.S. Drug Enforcement Agency. Thujone can cause an “unregulated legal high” in higher concentrations. The European Union limits thujone from Artemisia species to 35 mg/kg while the U.S. Food and Drug Administration requires less than 10 ppm to be “thujone‐free.” However, individuals can smoke or ingest A. absinthium in different forms. This study developed a polymerase chain reaction (PCR) high‐resolution melt (HRM) assay to detect and identify A. absinthium based on primer specificity, sensitivity, repeatability, and robustness. A triplex assay was performed with three “unregulated legal high” species: Datura stramonium, Merremia tuberosa, and A. absinthium; the PCR HRM assay detected and identified each plant at melt temperatures 77.42 ± 0.20°C, 83.88 ± 0.22°C, and 87.77 ± 0.15°C, respectively. The primer set developed distinguished A. absinthium from a variety of plant species and was successfully triplexed.     

温州汉族人群D7S2846、D19S400和D18S535基因座的遗传多态性研究

目的研究D7S2846、D19S400和D18S535位点在温州汉族人群的遗传多态性。方法EDTA抗凝血样采自194名无血缘关系温州地区汉族个体,用chelex-100法提取DNA,PCR扩增,聚丙烯酰胺凝胶电泳,银染显色分析。结果D7S2846观察到6个等位基因及15种基因型;D19S400观察到10个等位基因及36种基因型;D18S535观察到8个等位基因及26种基因型。各基因座的杂合度(H)分别为:0.644、0.724、0.772;个人识别能力(Dp):0.854、0.940、0.938。结论三个STR基因座具有较高杂合度,等位基因分布符合Hardy-Weinberg平衡,在法医学应用和群体遗传学研究中有较高的价值。     

超生反应阶段骨骼肌机械性损伤的形态学研究

对20例1．25～8．30hpm具有超生反应能力的尸检骨骼肌和17例10～24hpm和48～60hpm不具超生反应能力的尸检骨骼肌进行机械性损伤刺激的形态学系列对比研究。结果表明，经机械打击刺激后，具超生兴奋性的肌肉，受打击部位的肌纤维出现类似典型生前伤征象的形态学改变，而不具超生兴奋性的肌纤维仅出现被动的肌纤维断裂等非活性肌纤维改变。通过对超生形态学反应的形成机理进行探讨，为进一步研究超生形态学的作用提示了前景。     

浅谈公安院校课堂教学的现状及对策

本文是根据自己多年的公安教学实践写成的。在课堂教学中,深切体会到目前公安院校课堂教学的诸多弊端:教学方法单一;部分教师的教学囿于教材面上的内容;在传授知识的过程中,忽视学生能力的培养等等。针对上述问题,提出应全面提高公安院校师资队伍素质;改革教学方法和手段;改革教学内容和课程体系等对策。     

北京汉族群体9个STR位点的频率分布及法医学应用

提供北京汉族群体9个STR基因座的频率分布资料，了解其在法医学中的应用价值。应用PCR技术对9个STR基因座分3组进行复合扩增，经PAG电泳分离、银染，扫描仪扫描，计算机判读并保存结果，对北京地区汉族无关个体9个基因座的基因频率分布进行调查。结果显示，上述9个基因座的杂合度为0．6419～0．8092，多态性信息总量为0．9999，鉴别机率为0．9999，匹配机率为2．0×10-9和非父排除率为0．9985。STR3组9个基因座的综合检验可应用于法医学个体识别和亲子鉴定，并达到同一认定的标准。     

Use of a commercially available hydrogel as a novel DNA surface sampling tool

A common requirement in the military, law enforcement, and forensic mission space is the need to collect trace samples from surfaces using a method that not only readily captures the sample but also retains its integrity for downstream identification and characterization. Additionally, collecting samples from three-dimensional objects (e.g., shell casings) is a challenge for which there is currently no validated standardized approach. Recently, hydrogels have been shown to have the potential for surface collection of trace bacterial spores, amino acids, and DNA. To test whether these hydrogels can serve as a viable collection medium for sampling DNA from surfaces, we carried out a series of preliminary tests examining collection efficiency and suitability of hydrogel material to recover samples of diluted, dried human DNA on a smooth polycarbonate surface. The recovery of surface DNA using a commercially available hydrogel was examined, and the efficiency compared to samples collected using a standard foam collection swab. DNA collected using the hydrogel and swab methods was then examined using quantitative polymerase chain reaction (qPCR) and short tandem repeat (STR) analysis to determine whether the collection material was compatible with these downstream processes. The hydrogel material used for this study collected the experimental DNA with comparable efficiency to standard collection swabs. In addition, qPCR and STR analyses demonstrated compatibility with the hydrogel collection and extraction process. These data suggest that hydrogels have the potential to be used as sample collection materials and deserve further characterization to elucidate their utility in collection from irregularly shaped, three-dimensional surfaces/materials.     

A systematic approach to improve downstream single-cell analysis for the DEPArray™ technology

Most commercially available STR amplification kits have never been fully validated for low template DNA analysis, highlighting the need for testing different PCR kits and conditions for improving single-cell profiling. Here, current strategies rely mainly on adjusting PCR cycle number and analytical threshold settings, with a strong preference for using 30 amplification cycles and thresholds at 30–150 RFU for allele detection. This study aimed to (1) determine appropriate conditions for obtaining informative profiles utilizing a dilution series, and (2) test the outcome on single cells using the DEPArray™ technology. Four routinely applied forensic STR kits were compared by using three different amplification volumes and DNA dilutions down to 3.0 pg, while two well-performing kits were used for single/pooled leucocyte and sperm cell genotyping. Besides reduced costs, the results demonstrate that a 50%–75% PCR volume reduction was beneficial for peak height evaluation. However, this was counteracted by an increased artifact generation in diluted DNA volumes. Regarding profile completeness, the advantage of volume reduction was only prominent in samples processed with Fusion 6C. For single and pooled cells, ESIFast and NGMDetect provided a solid basis for consensus profiling regarding locus failure, although locus dropouts were generally observed as stochastic events. Amplification volume of 12.5 μL was confirmed as appropriate in terms of peak heights and stutter frequencies, with increased stutter peaks being the main artifact in single-cell profiles. Limitations associated with these analyses are discussed, providing a solid foundation for further studies on low template DNA.     

早期死亡时间推断研究进展

死亡时间推断在判断案件的性质、划定侦查范围及锁定嫌疑人等方面至关重要,一直是法医病理学工作的重点和难点。早期死亡时间,即指死后24 h以内,由于距离案发时间更短,对其准确推断能促进案件的成功侦破,具有重要的法医学意义。近年来,国内外法医学者运用一系列新方法和新技术对早期死亡时间推断进行了大量研究。本文对体液生物化学、超生反应、代谢组学、影像学、遗传物质降解规律等方面的研究进展进行综述,以期为早期死亡时间推断的研究和应用提供新的思路。     

15重快速STR复合扩增体系的构建

目的建立一套15重快速STR复合扩增体系。方法选择14个常染色体基因座以及1个性别基因座,采用Fast Start Taq DNA聚合酶系统,以DNA标准品9947A为模板,通过筛选扩增条件、选择热启动酶用量、调整引物平衡、优化快速扩增程序、筛选反应缓冲液、选择反应体系以及筛选添加剂等一系列复合扩增实验,比较各条件下等位基因丢失和非特异性扩增情况。结果在以1 ng DNA为模板、0.4μL聚合酶及10×Fast Start高保真反应缓冲液构成10μL快速体系的条件下,32 min即可获得标准DNA全部15个STR基因座的完整分型,无等位基因丢失和非特异性扩增现象,等位基因均衡性良好。同时,5%甘油、0.01%明胶、0.05%明胶和5 mmol/L硫酸铵可作为PCR扩增过程中拟加入的反应添加剂。结论本研究建立的15重快速STR复合扩增体系可以明显缩短反应时间,提高样品检测效率。