Optimization of the biological microchip for genotyping of the AB0 locus: correction of DNA probes

The objective of the present work was to search for methodological options facilitating the improvement and optimization of the biological microchip designed for genotyping of the AB0 locus. Testing a prototype biological microchip for genotyping of the AB0 locus using a reference set of preparations with the known group specificity has demonstrated that the choice of DNA probes by theoretical calculation of their thermodynamic parameters does not necessarily yields the desired practical result. Suffice it to say that under certain conditions some cells of the biochip appear to generate artifact hybridization signals that tend to make the results of genotyping either incorrect or difficult to interpret. This problem required the adjustment of the molecular structure of DNA probes for the optimization of their hybridization properties. As a result new DNA probes have been developed and synthesized and new variants of the prototype biochip constructed to be subjected to experimental verification.     

寡核苷酸芯片技术在HLA-A抗原基因分型中的应用研究

目的建立一种HLA-A位点的基因芯片分型方法,为HLA-A位点的基因分型提供一个较新的思路。方法利用基因芯片技术,根据HLA-A位点不同基因亚型的独特序列设计探针,制成分型芯片;待检测样品经PCR反应标记上荧光之后,与芯片进行杂交,根据杂交产生的荧光信号值分析确定样品HLA-A位点的基因亚型。将这一方法应用于100份标准DNA和200份无关个体的HLA-A位点基因分型并将部分样品进行测序。结果检测结果表明HLA-A基因分型芯片可准确分辨出A位点等位基因20大类,耗时2.5h。结论寡核苷酸芯片技术用于HLA-A基因分型,分辨率高、特异性强、重复性好、操作简便、结果直观,适合于法医学实践和临床应用。     

A novel method for ABO genotyping using a DNA chip

ABO genotyping is often performed to identify the blood type of decomposed samples, which is difficult to be determined by a serological test. In this study, we developed a simple method for ABO genotyping using a DNA chip. In this method, polymerase chain reaction-amplified and fluorescent-labeled fragments in the ABO gene and primate-specific D17Z1 were hybridized with DNA probes on a chip designed to detect single nucleotide polymorphisms (SNPs) in the ABO gene and part of the D17Z1 sequence. Using blood samples from 42 volunteers and 10 animal species, we investigated whether the chip could be used to detect SNPs in the ABO gene and the D17Z1 sequence. This method was then applied to various forensic samples, and it was confirmed that this method was suitable for the simultaneous analyses of ABO genotyping and species identification. This method fulfills the recent need for the development of rapid and convenient methods for criminal investigations.     

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.     

Typing of ABO locus with biological microchip as a new level in solution of problems in forensic-medical biological expertise of material evidences

There are cases in practice when during expertise of material evidences, discrepancies between results of typing of ABO antigens and molecular-genetic typing of DNA occur. In this work, as a radical approach to objective solution of similar conflict situations, for some contradictory case of expertise, all examinations were performed on the unified methodological base--DNA level. Instead of biological (isoserological) typing of ABO antigen, molecular-genetic typing of ABO locus with biological microchip was performed. In all cases the results, received with the use of biological microchip, do not contradict but completely conform to the results of others molecular-genetic examinations performed in the case. Given results indicate irrationality of further use of traditional methods of isoserological typing of ABO antigen for primary differentiation of biological material. These analyses, if necessary, have to be performed on DNA level with molecular-genetic expertise.     

单管实时PCR快速检验ABO基因型

目的建立快捷特异的ABO基因分型检测方法。方法根据ABO基因结构特点,设计特异性引物和四色双链探针,采用单管实时PCR方法检测ABO基因,结果与传统免疫学方法相对比。结果该方法可检出常见的3个等位基因,区分常见的6种基因型,全部检测过程可在100min内完成。110例中国人的随机个体定型结果与传统免疫学方法一致。结论实时PCR法进行ABO基因分型,简便快捷,灵敏度高,可以有效地为侦查破案服务。     

New York State TrueAllele® Casework Validation Study

DNA evidence can pose interpretation challenges, particularly with low‐level or mixed samples. It would be desirable to make full use of the quantitative data, consider every genotype possibility, and objectively produce accurate and reproducible DNA match results. Probabilistic genotype computing is designed to achieve these goals. This validation study assessed TrueAllele^® probabilistic computer interpretation on 368 evidence items in 41 test cases and compared the results with human review of the same data. Whenever there was a human result, the computer's genotype was concordant. Further, the computer produced a match statistic on 81 mixture items (for 87 inferred matching genotypes) in the test cases, while human review reported a statistic on 25 of these items (30.9%). Using match statistics to quantify information, probabilistic genotyping was shown to be sensitive, specific, and reproducible. These results demonstrate that objective probabilistic genotyping of biological evidence can reliably preserve DNA identification information.     

An STR Melt Curve Genotyping Assay for Forensic Analysis Employing an Intercalating Dye Probe FRET*

Abstract: The most common markers used in forensic genetics are short tandem repeats (STRs), the alleles of which are separated and analyzed by length using capillary electrophoresis (CE). In this work, proof of concept of a unique STR genotyping approach has been demonstrated using asymmetric PCR and a fluorescence resonance energy transfer (FRET)‐based hybridization analysis that combines fluorophore‐labeled allele‐specific probes and a DNA intercalating dye (dpFRET) in a melt match/mismatch analysis format. The system was successfully tested against both a simple (TPOX) and a complex (D3S1358) loci, demonstrated a preliminary detection limit of <10 genomic equivalents with no allelic dropout and mixture identification in both laboratory‐generated and clinical samples. With additional development, this approach has the potential to contribute to advancing the use of STR loci for forensic applications and related fields.     

不同方式标记非放射性探针原位杂交效果评价

目的比较不同方式标记非放射性探针的原位杂交效果。方法通过两种方法标记地高辛随机引物DNA探针和反意RNA探针,在大鼠损伤模型的皮肤组织上进行原位杂交。结果两种探针均可满足要求,以反意RNA探针在阳性染色深度和背景方面效果更佳。结论RNA探针在杂交效果方面优于DNA探针。     

Development and application of hydrogel oligonucleotide microchips for forensic-medical personal identification as illustrated by ABO locus

The article describes the method defining 5 alleles of ABO blood group typing system by molecular hybridization in hydrogel oligonucleotide microchip. The testing points were SNP variants in positions 261 and 297of exon 6 and in positions 646 and 657 of exon 7. Therefore, 5 ABO blood groups can be easily revealed: A, B, 0(1), 0(1v), 0(2). The method was tested on 10 DNA samples isolated from blood and saliva of unrelated individuals. The results were confirmed by sequencing of the identified allelic fragments. Estimation sensitivity was 25 pg of total DNA input. This technique is cost-effective and easy for use and, therefore, promising for forensic-medical personal identification.     

微滴式数字PCR技术用于生物样品种属鉴定和绝对定量

目的 运用微滴式数字PCR技术进行生物样品的种属鉴定和绝对定量.方法 选择人mtDNA两个编码基因ND4和16S rRNA,设计特异性引物与探针,用人来源及常见动物样本验证种属特异性,再用重组质粒和2组共16份人来源生物检材,倍比稀释.使用微滴式数字PCR技术进行种属检验和绝对定量,验证其灵敏度和稳定性.结果 人重组质粒FAM （ND4）可进行人来源样品的检测,其检测结果与各级稀释梯度基本吻合,微滴式数字PCR技术可以检测出反应体系中低至单拷贝的DNA.结论 微滴式数字PCR技术可以进行生物样品的种属鉴定和绝对定量,并具有很高的灵敏度和特异性,可应用于日常法医物证检验.     

The Optimization of Electrophoresis on a Glass Microfluidic Chip and its Application in Forensic Science

Microfluidic chips offer significant speed, cost, and sensitivity advantages, but numerous parameters must be optimized to provide microchip electrophoresis detection. Experiments were conducted to study the factors, including sieving matrices (the concentration and type), surface modification, analysis temperature, and electric field strengths, which all impact the effectiveness of microchip electrophoresis detection of DNA samples. Our results showed that the best resolution for ssDNA was observed using 4.5% w/v (7 M urea) lab‐fabricated LPA gel, dynamic wall coating of the microchannel, electrophoresis temperatures between 55 and 60°C, and electrical fields between 350 and 450 V/cm on the microchip‐based capillary electrophoresis (μCE) system. One base‐pair resolution could be achieved in the 19‐cm‐length microchannel. Furthermore, both 9947A standard genomic DNA and DNA extracted from blood spots were demonstrated to be successfully separated with well‐resolved DNA peaks in 8 min. Therefore, the microchip electrophoresis system demonstrated good potential for rapid forensic DNA analysis.     

ABO基因分型与多重STR联合检测在法医学中的应用

目的建立ABO基因型和Goldeneye16A试剂盒联合检测的方法,并评价其在法医学实践中的应用价值。方法将6种ABO基因型(A/A,A/O,B/B,B/O,A/B,O/O)的序列特异性引物(PCR-SSP)检测方法与Goldeneye16A试剂盒相整合进行同步分型。通过对460份男性个体血痕样本、9947A DNA及90份案件样本进行检测,考察方法的一致性、灵敏度及对法庭科学检材的适用性。结果应用本文方法可同时检出6种ABO基因型和15个常染色体STR基因座及性别决定基因座,检测灵敏度为125pg,其中ABO基因检测灵敏度达63pg。460份男性血痕和90份案件检材证实该联合分型方法用于各类检材结果准确、稳定。结论本文ABO基因分型与多重STR联合检测方法,适用于各类含有核细胞的生物检材,在法庭科学DNA鉴定中有较好的应用前景。     

Enhanced conditions for DNA fingerprinting with biotinylated M13 bacteriophage

Deoxyribonucleic acid (DNA) fingerprints are Southern blots which have a pattern resembling bar codes. The pattern is created by DNA probes that bind to variable-length repeated sequences of human genomic DNA digested with restriction endonucleases. To improve DNA fingerprints obtained with biotin-labeled M13mp8 replicative form (RF) bacteriophage as the gene probe, the conditions for hybridization and the subsequent washing steps of the filter were refined. Experiments were conducted varying the electrophoresis time, blotting membranes, hybridization solution, and posthybridization washes. The simplicity, sensitivity, and reliability of this nonistopic technique make possible its application for identification of individuals within a species, for parentage testing, and for monitoring bone marrow transplantation.     

Identification in blood stains through DNA typing with C4 and HLA-DR probes

A restriction fragment length polymorphism analysis using double digestion of DNA preparations with XbaI and BglII restriction enzymes and hybridization with C4 and HLA-DR probes is described. The typing conditions selected reveal extensive individual variation in both C4 and DR gene regions. In our panel of 46 unrelated individuals, 37 different phenotypic patterns were recognized when both probes were used, and preliminary discriminative power values of 0.865 and 0.914 were calculated for C4 and DR beta, respectively. The probability of a chance match using both systems is probably about 1.5.10(-2). The potential of this method for individual identification of blood stains was demonstrated on DNA prepared from 6-month-old dried blood stains from seven panel individuals. The seven individuals were all identified when comparing stain DNA patterns with panel control patterns. No RFLP pattern changes were observed following storage of blood stains. Based on these experiments with C4 and DR beta DNA typing under laboratory conditions, it is concluded that DNA typing with such probes may become a powerful tool in future stain identification analyses.     

微腔型PCR芯片用于法医DNA分析的初步研究

目的为了克服传统PCR热循环仪体积大,运行电压高,耗时长,只能在实验室中应用的缺点,研究了一种微腔型PCR芯片,以期实现现场对STR片段的复合扩增。方法采用在PCR反应缓冲液中加入不同浓度的BSA溶液对芯片进行表面优化处理的方法及不同酶量优化实现对STR片段的有效扩增。结果使用浓度为0．5mg／mL的BSA可得到清晰完整的STR分型结果;加大酶量有益于扩增效率的提高。结论该种微腔型PCR芯片经初步优化后可有效地对STR片段进行复合扩增,经进一步优化可真正实现法医DNA分析的更加微量化和快速化。     

DNA纹印技术的初步研究——用PYNH24探针分析MspI的RFLP

应用 Southern 印迹杂交技术,分析了人体基因组 DNA MspI 酶解物与特异探针 PYNH24杂交的限制酶切片段长度多态性,获得清晰易读的杂交图谱。50个不相关个体血样中未发现相同图谱,显示了个体特异性,为法医生物物证检验工作提供了新的分析手段。     

Validation of a microchip electrophoresis system as a DNA amplification control

As part of the normal procedure in a forensic DNA laboratory, a quality control step of the amplified DNA is often implemented to ensure the correct amplification of the sample before it is analysed in downstream applications. A validation study was undertaken to investigate a new microchip electrophoresis system (MultiNa, Shimadzu Corporation) claiming high resolution and sensitivity compared to routine polyacrylamide gel electrophoresis (PAGE). An array of STR multiplexes (AmpFISTR™ SGM+, GenePrint^® FFFL, PowerPlex™ 16, PowerPlex™ Y, an in-house Y-STR multiplex and AmpFISTR™ Profiler) was tested under both standard and low copy number PCR parameters to evaluate the accuracy, reproducibility and sensitivity of this technique. These tests showed that the microchip system did not have improved sensitivity compared to PAGE though had increased resolution and high reproducibility between samples.     

A quantitative PCR assay for the assessment of DNA degradation in forensic samples

A multiplex quantitative PCR assay has been designed to amplify target sequences of different length, which allows for the assessment of DNA degradation in samples of forensic interest. The targets were chosen to provide quantification and fragment length information relevant to the STR amplification targets commonly used for forensic genotyping. The longer target (nuTH01, 170-190 bp) spans the TH01 STR locus. Although not one of the longest loci used for STR genotyping, it was chosen as a good compromise given the target length limitations on qPCR efficiency with TaqMan detection. The shorter target (nuCSF, 67 bp) was designed in the upstream flanking region of the CSF1PO STR locus. In addition to these human nuclear targets, the assay includes an internal PCR control target sequence to allow for an assessment of PCR inhibition. The assay was rigorously tested on samples with varying amounts of degradation, and the ratio of nuCSF:nuTH01 quantifications was shown to provide a good estimation of the degree of degradation present in a sample. This estimate, along with the internal control for PCR inhibition, provides a valuable tool for post-extraction sample assessment.     

吸附性载体上微量血痕的DNA分型

目的研究吸附性载体上微量血痕的DNA提取及其检验。方法用Chelex-100法、QIAamp MiniKit、及QIAamp Mini Kit改良法提取吸附性载体上微量血痕中的DNA,进行PCR扩增及STR检验。结果采用Chelex-100法及QIAamp Mini Kit的分型成功率很低;采用QIAamp Mini Kit的改良法能较好的得到分型图谱。结论采用QIAamp Mini Kit的改良法能较好的提取吸附性载体上微量血痕的模板DNA。