Search

Nowadays, kinship testing is very common in forensic caseworks, but the power of autosomal short tandem repeats (A-STRs) may be limited in complex cases. X-Chromosome short tandem repeats (X-STRs), having a unique heritage mode, should be of special use in some deficient cases. To evaluate and compare the potential of A-STR and X-STR as supplement genetic markers in deficient kinship testing, we simulated 10,000 duos for each of 18 kinds of relationships involving full sibling, half-sibling, grandparent-grandchild, and uncle/aunt-nephew/niece. Loci from STRTyper10, PowerPlex 16, and Investigator Argus X-12 were studied in Southern Han Chinese and the distribution of likelihood ratio (LR) values was analysed. With the addition of the X-12 system, the distribution of LR values for the full sisters, paternal half-sisters, paternal grandmother-granddaughters, maternal aunt-nieces, and maternal aunt-nephews separated much more obviously from those of unrelated duos, and the effectiveness was 1.0000, 0.99865, 0.9991, 0.8996 and 0.9634, respectively, which was more efficient than A-STRs. For the individual duos with other relationships, the effects of adding X-STRs and A-STRs were similar. Therefore, for the Southern Han Chinese, X-STRs can be very useful in kinship testing involving full sisters, paternal half-sisters, paternal grandmother-granddaughters, and maternal aunt-nieces/nephews.

Aims Decomposition, a complicated process, depends on several factors, including carrion insects, bacteria and the environment. However, the composition of and variation in oral bacteria over long periods of decomposition remain unclear. The current study aims to illustrate the composition of oral bacteria and construct an informative model for estimating the post-mortem interval (PMI) during decomposition. Methods and Results Samples were collected from rats' oral cavities for 59 days, and 12 time points in the PMI were selected to detect bacterial community structure by sequencing the V3–V4 region of the bacterial 16S ribosomal RNA (16S rRNA) gene on the Ion S5 XL platform. The results indicated that microorganisms in the oral cavity underwent great changes during decomposition, with a tendency for variation to first decrease and then increase at day 24. Additionally, to predict the PMI, an informative model was established using the random forest algorithm. Three genera of bacteria (Atopostipes, Facklamia and Cerasibacillus) were linearly correlated at all 12 time points in the 59-day period. Planococcaceae was selected as the best feature for the last 6 time points. The R2 of the model reached 93.94%, which suggested high predictive accuracy. Furthermore, to predict the functions of the oral microbiota, PICRUSt results showed that energy metabolism was increased on day 3 post-mortem and carbohydrate metabolism surged significantly on days 3 and 24 post-mortem. Conclusions Overall, our results suggested that post-mortem oral microbial community data can serve as a forensic resource to estimate the PMI over long time periods. Significance and Impact of the Study The results of the present study are beneficial for estimating the PMI. Identifying changes in the bacterial community is of great significance for further understanding the applicability of oral flora in forensic medicine.

At present, the orderly assembly of bio-cellulose nanofibers (CNFs) with excellent mechanical properties in a simple and continuous manner still remains a challenge. Here, we propose a strategy of combining a wet spinning process with a self-made grading-stretching device to realize the continuous preparation of high-performance bacterial cellulose (BC) macrofibers. The macrofiber obtained by one-stage stretching at the optimum stretching ratio of 40% achieves the Young's modulus of 19.8 GPa and tensile strength of 544.5 MPa. Under two-stage stretching, wide-angle X-ray (WXRD) diffraction analysis revealed that the second orientation of nanofibers shows a higher degree of orientation than that under one-stage stretching. The maximum Young's modulus and tensile strength of the macrofiber can reach 33.2 GPa and 659.8 MPa, respectively, which are higher than most CNFs macrofibers obtained by spinning and post-stretching. This research is expected to provide a significant reference for the industrial spinning of nanocellulose.

Short tandem repeats (STRs) are the most widely used genetic markers in forensic application, but they are not ideal genetic markers for the analysis of forensic challenging samples such as highly degraded or unbalanced mixed samples because of their relatively large amplicons and stutter peaks. In this study, we developed a set of short microhaplotypes based on non-binary SNPs with molecular extent sizes no longer than 60 bases and genotyped 100 unrelated individuals from northern Han groups. Our results showed this panel has similar discrimination power to STR kits, as the combined random match probability (CMP) reached 1.396 × 10−22 and mean effective number of alleles (Ae) was 3.59. The cumulative probability of exclusion for duos (CPE-duos) was 0.999919 and the cumulative probability of exclusion for trios (CPE-trios) was 0.9999999987, suggesting this panel could be applied for forensic personal identification and parentage testing independently. Population differentiation in 26 populations from the 1000 Genomes Project indicated this panel could distinguish populations from Africa, East Asia, South Asia, America, and Europe. These microhaplotypes based on non-binary SNPs have short amplicons, good discrimination power, no stutter artifacts, and have great potential in detection of highly degraded and unbalanced mixtures for personal identification, paternity testing, and ancestry inference.

With a unique inheritance pattern compared to autosomal short tandem repeats (A-STRs), X chromosomal STRs (X-STRs) have special usage in forensic relationship testing. In this study, we designed a multiplex amplification system (named TYPER-X19 multiplex assay) consisting of 18 STR loci spreading from 7.837 to 149.460 Mb on the X chromosomes (DXS9895, DXS8378, DXS9902, DXS6810, DXS7132, DXS10079, DXS6789, DXS7424, DXS101, DXS6797, DXS7133, DXS6804, GATA165B12, DXS10103, HPRTB, GATA31E08, DXS8377, and DXS7423), and the amelogenin. PCR primers were marked with four kinds of fluorophores including FAM, HEX, TAMRA, and ROX. The multiplex system was optimized and tested for precision, concordance, reproducibility, sensitivity, stability, DNA mixture, and species specificity according to the conventional validation guidelines. The results indicated that the system was accurate, reliable, and sensitive enough, and was suitable for common forensic case-type samples. In the population genetic study, a total of 148 alleles were detected at the 18 X-STR loci in 398 Southern Han Chinese. Relatively high combined power of discrimination in male (PDm ), power of discrimination in female (PDf ), mean paternity exclusion chance in trios (MECtrio ), and mean paternity exclusion chance in duos (MECDuo ) by Desmarais were detected, and HPRTB-DXS10103 was in linkage disequilibrium. The results suggested that the TYPER-X19 multiplex assay was suitable for forensic applications.

The ABO blood group is considered to be one of the most important markers in forensic testing. Additionally, autosomal short tandem repeat (STR) genotyping continues to be recognized as the dominan...

Ili is located in northernmost Xinjiang, China. The Uyghur population only accounts for 15.90% of the total population in the nation. There is currently no large population data-based data set in Ili Uyghur. In this study, we investigated the genetic diversities of 18 autosomal short tandem repeat (STR) loci in 1129 Uyghur individuals living in Ili. The values of combined power of discrimination (CPD) and combined probability of exclusion (CPE) were 0.99999999999999999999990244 and 0.99999995645, respectively. Furthermore, we explored the genetic relationships between the Ili Uyghur population and 32 previously published populations. The results indicated that the Ili Uyghur population was more closely related to the Xinjiang Kazakh population. In addition, It was worth noting that significant differences were observed between Ili the Uyghur population and the Uyghur1 and Uyghur2 populations at the shared 15 loci, with significant differences at 7 and 11 loci after Bonferroni adjustment (p = 0.05/495 ≈ 0.00010).

Next-generation sequencing (NGS) has been used to genotype forensic short tandem repeat (STR) markers for individual identification and kinship analysis. STR data from several NGS platforms have been published, but forensic application trials using the Ion S5™ XL system have not been reported. In this work, we report sensitivity, reproducibility, mixture, simulated degradation, and casework sample data on the Ion Chef™ and S5™ XL systems using an early access 25-plex panel. Sensitivity experiments showed that over 97% of the alleles were detectable with down to 62 pg input of genomic DNA. In mixture studies, alleles from minor contributors were correctly assigned at 1:9 and 9:1 ratios. NGS successfully gave 12 full genotype results from 13 challenging casework samples, compared with five full results using the CE platform. In conclusion, the Ion Chef™ and the Ion S5™ XL systems provided an alternative and promising approach for forensic STR genotyping.

Short tandem repeat (STR) genotyping methods are widely used for human identity testing applications, including forensic DNA analysis. Samples of DNA containing the length-variant STR alleles are typically separated and genotyped by comparison to an allelic ladder. Here, we describe a newly devised library of cloned STR alleles. The library covers alleles X and Y for the sex-determining locus Amelogenin and 259 other alleles for 22 autosomal STR loci (TPOX, D3S1358, FGA, D5S818, CSF1PO, D7S820, D8S1179, TH01, vWA, D13S317, D16S539, D18S51, D21S11, D2S1338, D6S1043, D12S391, Penta E, D19S433, D11S4463, D17S974, D3S4529 and D12ATA63). New primers were designed for all these loci to construct recombinant plasmids so that the library retains core repeat elements of STR as well as 5'- and 3'-flanking sequences of ∼500 base pairs. Since amplicons of commercial STR genotyping kits and systems developed in laboratories are usually distributed from 50 to

Search for traces: Aptamer-bound Au nanoparticles (Au NPs) were used to provide high-resolution dark-field microscopy images of latent fingerprints (LFPs) with level 2 and level 3 details. Furthermore, the cocaine-induced aggregation of Au NPs results in a true green-to-red color change of the scattered light, providing a quasi-quantative method to identify cocaine loadings in LFPs.

Mixed semen stains from multiple contributors are challenging samples in sexual assault casework, and it is crucial to obtain the DNA profiles of different donors to allow the evidence to play an important role in investigations and judicial proceedings. Current standard procedures, including preferential lysis, are incapable of separating single-source sperm from multiple male donors. Mixed profiles are often obtained and may not directly exclude or identify suspects. In this case, computational methods for mixture interpretation are often used, which rely on different types of calculation models. Here, we explored a new strategy for sperm cell isolation and detection from mixtures. It is a direct way to obtain genotypes of different sperm donors compared to computation-based mixture interpretation. Laser capture microdissection (LCM) and low volume-PCR (LV-PCR) were used for single sperm isolation and detection. The platform was sensitive; profiling of a single sperm cell generated a minimum of 13-16 loci in 73.1% of Y short tandem repeat (Y-STR) assays. A new Y-STR and autosomal STR multiplex system (YA-STR) were optimized by the combination of the Y-STR locus and 10 autosomal STR (auto STR) loci. The Y-STR locus acted as a tag to discriminate profile groups from different donors. Subsequently, consensus auto STR profiles of various persons could be received. The accuracy and availability of this method were evaluated on a three-donor semen mixture and found to be effective for the resolution of a multi-donor sperm mixture.

A novel fluorescent single nucleotide polymorphism (SNP) assay was developed by using Graphene Oxide (GO), which provides a fast, sensitive and simple method for SNP detection. The strategy was based on the single base extension reaction and different absorption capacity of fluorescein labeled dGTP (dGTP-Fl) and double-stranded DNA (dsDNA) to GO. dGTP-Fl is incorporated into the probe by extension reaction for the mutant target but not for the wild target, which leads to recovered fluorescence for the mutant target because of weak interaction between dsDNA and GO and weak fluorescence for the wild target because of the quenched fluorescence of dGTP-Fl by GO. The method shows a linear range for the mutant-type target from 3 nM to 50 nM and 3 nM is the detection limit. It was noted that as low as 10% mutant-type target could be detected in the presence of the wild-type target, in which the concentration is 9 times higher than that of the mutant-type target.

We herein report a power-free microfluidic chip for fluorescent DNA detection with high single-nucleotide polymorphism discrimination, using a DNA intercalator and graphene oxide.

Here, we have demonstrated an ultra-high sensitive detection platform with the detection limit of 5 pM for an environmental toxin-Pb2+. We designed a Pb2+ triggered exonuclease aided DNA recycling system to improve the detection sensitivity. In our system, a Pb2+ dependent 8-17 DNAzyme and its substrate were used to form hybridization duplex. In the presence of Pb2+, the substrate was cleaved and disassociated from the duplex. Then, the released 8-17 DNAzyme was used as a target of the exonuclease aided DNA recycling system which can amplify the fluorescence signal by recycling the 8-17 DNAzyme continuously. Then, the sensitive Pb2+ detection are accomplished and the detection limit of Pb2+ was down to 5 pM which is about 1000 times lower than the traditional detection method based on the 8-17 DNAzyme. (C) 2013 Elsevier B.V. All rights reserved.

Vaginal swabs taken in rape cases usually contain epithelial cells from the victim and sperm from the assailant and forensic DNA analysis requires separation of sperm from these cell mixtures. PH-20, which is a glycosylphosphatidylinositol-anchored hyaluronidase located on the head of sperm, has important functions in fertilization. Here we describe a newly developed method for sperm isolation using anti-PH-20 antibody-coupled immunomagnetic beads (anti-PH-20 IMBs). Optical microscopy and scanning electron microscopy showed the IMBs recognized the head of sperm specifically and exhibited a great capacity to capture sperm cells. However, we found it necessary to incubate the IMB-sperm complex with DNase I before sperm lysis in order to remove any female DNA completely. We compared the sensitivity of anti-PH-20 IMBs in sperm and epithelial cell discrimination to those coated with a different anti-sperm antibody (anti-SP-10, anti-ADAM2 or anti-JLP). Only the anti-PH-20 IMBs succeeded in isolating sperm from cell mixtures at a sperm/epithelial cell ratio of 103:105. Further, our method exhibited greater power and better stability for sperm isolation compared to the traditional differential lysis strategy. Taken together, the anti-PH-20 IMB method described here could be effective for the isolation of sperm needed to obtain a single-sourced DNA profile as an aid to identifying the perpetrator in sexual assault cases.

It has been a challenge to extract DNA from bones previously soaked in water, burned, or buried for a long time, due to the reduced quality and quantity of DNA in the bone samples. The dramatic degradation of the DNA and the presence of PCR inhibitors in the collagen significantly complicate the process of DNA identification in dated and charred bones. In this article, we present a novel strategy to obtain DNA from bones based on the use of cetyltrimethylammonium bromide (CTAB) lysis buffer and isoamyl alcohol-chloroform extraction with subsequent DNA purification using the DNA IQ System, or alternatively the QIAquick system. When applied to bones soaked, burned or buried for up to nine years, this method increases the purity and yield of DNA with respect to the traditional phenol-chloroform method and significantly improves multiplex STR genotyping using fluorescence-based methods. The results of this research will assist forensic scientists in the identification of DNA from victims whose bodies underwent significant trauma or burning, precluding the utilization of traditional forensic DNA identification techniques.