Single-nucleus transcriptomic mapping uncovers targets for traumatic brain injury.

The subventricular zone (SVZ) is a neurogenic niche that contributes to homeostasis and repair after brain injury. However, the effects of mild traumatic brain injury (mTBI) on the divergence of the regulatory DNA landscape within the SVZ and its link to functional alterations remain unexplored. In this study, we mapped the transcriptome atlas of murine SVZ and its responses to mTBI at the single-cell level. We observed cell-specific gene expression changes following mTBI and unveiled diverse cell-to-cell interaction networks that influence a wide array of cellular processes. Moreover, we report novel neurogenesis lineage trajectories and related key transcription factors, which we validate through loss-of-function experiments. Specifically, we validate the role of Tcf7l1, a cell cycle gene regulator, in promoting neural stem cell differentiation toward the neuronal lineage after mTBI, providing a potential target for regenerative medicine. Overall, our study profiles an SVZ transcriptome reference map, which underlies the differential cellular behavior in response to mTBI. The identified key genes and pathways that may ameliorate brain damage or facilitate neural repair serve as a comprehensive resource for drug discovery in the context of mTBI.

Improving DNA mixtures analysis using compound markers composed of InDels and SNPs screened from the whole genome with next-generation sequencing.

Next-generation sequencing (NGS) allows for better identification of insertion and deletion polymorphisms (InDels) and their combination with adjacent single nucleotide polymorphisms (SNPs) to form compound markers. These markers can improve the polymorphism of microhaplotypes (MHs) within the same length range, and thus, boost the efficiency of DNA mixture analysis. In this study, we screened InDels and SNPs across the whole genome and selected highly polymorphic markers composed of InDels and/or SNPs within 300 bp. Further, we successfully developed and evaluated an NGS-based panel comprising 55 loci, of which 24 were composed of both SNPs and InDels. Analysis of 124 unrelated Southern Han Chinese revealed an average effective number of alleles (Ae ) of 7.52 for this panel. The cumulative power of discrimination and cumulative probability of exclusion values of the 55 loci were 1-2.37 × 10-73 and 1-1.19 × 10-28 , respectively. Additionally, this panel exhibited high allele detection rates of over 97% in each of the 21 artificial mixtures involving from two to six contributors at different mixing ratios. We used EuroForMix to calculate the likelihood ratio (LR) and evaluate the evidence strength provided by this panel, and it could assess evidence strength with LR, distinguishing real and noncontributors. In conclusion, our panel holds great potential for detecting and analyzing DNA mixtures in forensic applications, with the capability to enhance routine mixture analysis.

From degraded to deciphered: ATAC-seq's application potential in forensic diagnosis.

In recent years, molecular biology-based diagnostic techniques have made remarkable strides and are now extensively utilized in clinical practice, providing invaluable insights for disease diagnosis and treatment. However, forensic medicine, especially forensic pathology, has witnessed relatively limited progress in the application of molecular biology technologies. A significant challenge in employing molecular techniques for forensic diagnoses lies in the quantitative and qualitative changes observed in diagnostic markers due to sample degradation-a recognized and formidable obstacle. Inspired by the success of DNA sequencing in forensic practices, which enables accurate individual identification even in cases involving degraded and deteriorated tissues and organs, we propose the application of the assay for transposase-accessible chromatin with sequencing (ATAC-seq) to identify targets at the transcriptional onset, exploring chromatin and DNA-level alterations for injury and disease inference in forensic samples. This study employs ATAC-seq to explore alterations in chromatin accessibility post-injury and their subsequent changes over a 2-h degradation period, employing traumatic brain injury (TBI) as a representative model. Our findings reveal high sensitivity of chromatin accessibility sites to injury, evidenced by shifts in thousands of peak positions post-TBI. Remarkably, these alterations remain largely unaffected by early degradation. Our results robustly endorse the notion that integrating and incorporating these specific loci for injury and disease diagnosis in forensic samples holds tremendous promise for practical application. We further validated the above results using human cortical tissue, which supported that early degradation did not significantly affect chromatin accessibility. This pioneering advancement in molecular diagnostic techniques may revolutionize the field of forensic science, especially forensic pathology.

Assessment of ForenSeq mtDNA Whole Genome Kit for forensic application.

Mitochondrial DNA (mtDNA) is an indispensable genetic marker in forensic genetics. The emergence and development of massively parallel sequencing (MPS) makes it possible to obtain complete mitochondrial genome sequences more quickly and accurately. The study evaluated the advantages and limitations of the ForenSeq mtDNA Whole Genome Kit in the practical application of forensic genetics by detecting human genomic DNA standards and thirty-three case samples. We used control DNA with different amount to determine sensitivity of the assay. Even when the input DNA is as low as 2.5 pg, most of the mitochondrial genome sequences could still be covered. For the detection of buccal swabs and aged case samples (bloodstains, bones, teeth), most samples could achieve complete coverage of mitochondrial genome. However, when ancient samples and hair samples without hair follicles were sequenced by the kit, it failed to obtain sequence information. In general, the ForenSeq mtDNA Whole Genome Kit has certain applicability to forensic low template and degradation samples, and these results provide the data basis for subsequent forensic applications of the assay. The overall detection process and subsequent analysis are easy to standardize, and it has certain application potential in forensic cases.

An overview of SNP-SNP microhaplotypes in the 26 populations of the 1000 Genomes Project.

Microhaplotypes (MHs) are a promising new type of forensic markers that are defined by the combinations of two- or more single-nucleotide polymorphisms (SNPs) within 200 bp. Their advantages, such as low mutation rates, lack of stutter artifacts, and short amplicons, have improved human identification, kinship analysis, ancestry prediction, and mixture deconvolution capabilities. Information on published MHs, e.g., allele frequencies, is available in widely used public databases, ALlele FREquency Database, and MicroHapDB. However, there are abundant non-published MHs spread over the whole genome, and those databases do not incorporate other databases (e.g., the SNP Database) to provide users with more integrated information. Therefore, it is essential to establish a robust, responsive, and comprehensive MHs database. In this study, we thoroughly screened for SNP-SNP MHs among 26 populations from the 1000 Genomes Project (Phase 3). All genotype data of SNPs in each MH were converted to PHASE input files, and allele frequencies were estimated using PHASE. We compiled a detailed summary of SNP-SNPs at the global, continental, and population levels focused on haplotypes and the Ae value and supplemented our database using dbSNP data (last updated in 2015). We have successfully established a dual-SNP MH database (D-SNPsDB) of MHs within 50 bp for 26 populations in the integration of basic data such as physical positions in the human genome, mapping of variant identifiers (rsIDs), allele frequencies, and basic variant information. For public database queries, the D-SNPsDB web app was developed with the R Shiny package to get integrated information.

Validation of the Microreader 40Y ID System: a Y-STR multiplex for casework and database samples.

Y-chromosome-specific short tandem repeat loci (Y-STRs) are commonly analysed in forensic science for paternity testing, familial searches, and, in sexual assault cases, to determine male DNA identity from mixed sources with high background female DNA content. The Microreader 40Y ID System is a six-dye multiplex amplification kit that contains 17 Y-STR loci from the Yfiler Plus PCR Amplification Kit and the powerplex Y23 system (DYS19, DYF385a/b, DYS389I/II, DYS390, DYS391, DYS392, DYS393, DYS437, DYS438, DYS439, DYS448, DYS456, DYS458, DYS549, DYS635(Y GATA C4), DYS643, Y GATA H4, DYS460, DYS481, DYS533, DYF387S1, DYS449, DYS518, DYS570, DYS576, and DYS627), plus six high polymorphic loci (DYS444, DYS447, DYS557, DYS596, DYS527 a/b) as well as 4 additional candidate Y-STR loci (DYS593, DYF404S1, DYS645) and a Y-Indel loci (Rs2032678), thereby providing greater efficiency, compatibility, and accuracy. The Microreader 40Y ID System can directly amplify markers from blood or saliva on filter paper or FTA cards, without template extraction or purification, and can also be used for extracted DNA templates. To verify the efficiency and accuracy of the kit, the Microreader 40Y ID System was validated by investigating sensitivity, amplification conditions, male-male and male-female mixtures, PCR inhibition, species specificity, reproducibility, and efficacy with degraded samples. The Y-STR loci were also tested using 437 male samples from Tibet, Han, and Yi. The Microreader 40Y ID System was able to compensate for some of the shortcomings of Y-STR markers in practical applications, such as cost and profile interpretation, and fully meets the domestic Y chromosome database construction specifications and requirements.

Feasibility of using probabilistic methods to analyse microRNA quantitative data in forensically relevant body fluids: a proof-of-principle study.

Several studies have confirmed that microRNAs (miRNAs) are promising markers for body fluid identification since they were introduced to this field. However, there is no consensus on the choice of reference genes and identification strategies. In this study, 13 potential candidate miRNAs were screened from three forensically relevant body fluid datasets, and the expression of 12 markers in five body fluids was determined using a real-time quantitative method. Two probabilistic approaches, Naive Bayes (NB) and partial least squares discriminant analysis (PLS-DA), were then applied to predict the origin of the samples to determine whether probabilistic methods are helpful in body fluid identification using miRNA quantitative data. Furthermore, 14 reference combinations were used to validate the influence of different reference choices on the predicted results simultaneously. Our results showed that in the NB model, leave-one-out cross-validation (LOOCV) achieved 100% accuracy and the prediction accuracy of the test set was 100% in most reference combinations. In the PLS-DA model, the first two components could interpret about 80% expression variance and LOOCV achieved 100% accuracy when miR-92a-3p was used as the reference. This study preliminarily proved that probabilistic approaches hold huge potential in miRNA-based body fluid identification, and the choice of references influences the prediction results to a certain extent.

A new approach to detect a set of SNP-SNP markers: Combining ARMS-PCR with SNaPshot technology.

Microhaplotypes are a new promising type of forensic genetic marker. Without the interference of stutter and high mutation rates as for STRs, and with short amplification lengths and a higher degree of polymorphism than single SNP, microhaplotypes composed of two SNPs, SNP-SNP, have a strong application potential. Currently, the most common method to detect microhaplotypes is massive parallel sequencing. However, the cost and extensive use of instruments limit its wide application in forensic laboratories. In this study, we screened 23 new SNP-SNP loci and established a new detection method by combining a multiplex amplification refractory mutation system-based PCR (ARMS-PCR) and SNaPshot technology based on CE. First, we introduced an additional deliberate mismatch at the antepenultimate base from the 3' end of primers when designing ARMS-PCR for SNP 1 (the first SNP of the SNP-SNP). Then, single base extension primers for SNaPshot assay were designed next to the position of SNP 2 (the second SNP). Finally, 15 loci were successfully built into four panels and these loci showed a relatively high level of polymorphism in the Southwest Chinese Han population. All the loci had an average probability of informative genotypes (I value) of 0.319 and a combined discrimination power of 0.999999999. Therefore, this new detection system will provide a valuable supplement to current methods.

Postmortem interval determination using mRNA markers and DNA normalization.

Postmortem interval (PMI) determination is an important part of criminal investigations, but it is still subject to uncertainty. Degradation of mRNA in PMI determination has been studied in decays; however, some studies have reported no correlation between PMI and RNA degradation. Thus, we aimed to determine whether RNA quantity was correlated with PMI. Heart and brain tissues were separated from a mouse model of a 0-48 h PMI with 29 time points. We then coextracted the DNA and RNA in one tube with Bioteke coextraction kits and selected some mRNA markers associated with cell oxygen deprivation and apoptosis as target genes, such as hypoxia-associated factor (HAF), apoptosis-inducing factor (AIF), hypoxia-inducible factor 2 alpha (HIF2a), and factor inhibiting HIF (FIH). We measured the quantity of these markers using real-time quantitative PCR (qPCR), and Caspase-3 DNA and 18S were each used for normalization. The results showed that in the heart tissue, the degradation of HIF2a, AIF, and FIH was correlated with PMI, as was the degradation of HIF2a, FIH, and AIF in brain tissue when normalized with Caspase-3 DNA. However, when normalized with 18S, only the degradation of HIF2a in brain tissue was correlated with PMI. Interestingly, the quantity of HAF in brain tissue was found to increase after death with either 18S or Caspase-3 DNA normalization, and it was significantly correlated with 0-48 h PMI. These results indicated that mRNA quantity can be used to determine PMI and that Caspase-3 DNA is feasible for PMI estimation. In summary, we established mathematical models for PMI determination using multiple mRNA markers and multiple tissues and further studies are needed to validate and investigate these markers and mathematical models in human tissues.Duo Peng and Meili Lv contributed equally to this work.

Developmental validation of the Microreader™ 20A ID system.

The Microreader™ 20A ID system is designed for forensic applications such as personal identification, parentage testing, and research. It includes 13 combined DNA index system (CODIS) short tandem repeat (STR) loci (CSF1PO, FGA, TH01, TPOX, vWA, D3S1358, D5S818, D7S820, D8S1179, D13S317, D16S539, D18S51, and D21S11), three expanded CODIS STR loci (D12S391, D19S433, and D2S1338), three non-CODIS STR loci (D6S1043, Penta D, and Penta E), and the amelogenin locus in one reaction with a six-dye fluorescent (FAM, HEX, TAMAR, ROX, PUR, and QD550) analysis system. In this study, the Microreader™ 20A ID system was validated according to the Scientific Working Group on DNA Analysis Methods validation guidelines for forensic DNA Analysis methods and Chinese national standard, including PCR-based studies, sensitivity study, precision, and accuracy evaluation, stutter calculation, inhibitor tests, species specificity, and DNA mixture studies. Our results suggest that the Microreader™ 20A ID system is a useful tool for personal identification and parentage testing.

Evaluation of the microhaplotype markers in kinship analysis.

Microhaplotype markers are emerging forensic genetic markers, which may supplement existing markers. Consisting of two to four SNPs with an extent of <200 bp, microhaplotype can be genotyped through massively parallel sequencing technology. Articles that have been published suggested that microhaplotype markers have good application prospect in forensics. Multiallelic haplotype loci are potentially important in certain forensic works, as the stutter and high mutation rate of short tandem repeats and the low polymorphism of single nucleotide polymorphisms may limit the power of these two kind of regular markers. In this study, we explored the potential of 11 new microhaplotype loci in kinship analysis. The results suggested that these loci have relatively high polymorphic information in different populations worldwide and relatively high system effectiveness in the kinship analysis. Microhaplotypes have potential for forensic kinshipg analysis.

Population genetic analysis of 30 insertion-deletion (INDEL) loci in a Qinghai Tibetan group using the Investigator DIPplex Kit.

The Qiagen Investigator® DIPplex Kit multiplexes 30 autosomal INDELs plus amelogenin for forensic use. The aim of this study was to estimate the diversity of 30 INDEL loci in a sample of 530 Tibetan individuals from Qinghai Province, China, and to evaluate the usefulness of these loci for forensic genetics. The observed heterozygosity ranged from 14.3 to 53.4%, and combined power of discrimination, matching probability, and cumulative probability of exclusion were 0.99999999999172, 8.27999 × 10-12, and 0.9897, respectively, in the Qinghai Tibetan group. The results of pairwise genetic distance, principal component analysis, a multi-dimensional scaling plot, and a neighbour-joining tree between the Qinghai Tibetan and 49 reference populations revealed significant genetic differences between continental populations and a close genetic relationship between the Qinghai Tibetan and East Asian populations. This study indicates that the Investigator® DIPplex Kit can serve as an effective supplementary tool for forensic genetic tasks.

Developmental validation of an mRNA kit: A 5-dye multiplex assay designed for body-fluid identification.

Identifying the sources of biosamples found at crime scenes is crucial for forensic investigations. Among the markers used for body fluid identification (BFI), mRNA has emerged as a well-studied marker because of its high specificity and remarkable stability. Despite this potential, commercially available mRNA kits specifically designed for BFI are lacking. Therefore, we developed an mRNA kit that includes 21 specific mRNA markers of body fluids, along with three housekeeping genes for BFI, to identify four forensic-relevant fluids (blood, semen, saliva, and vaginal fluids). In this study, we tested 451 single-body-fluid samples, validated the universality of the mRNA kit, and obtained a gene expression profile. We performed the validation studies in triplicates and determined the sensitivity, specificity, stability, precision, and repeatability of the mRNA kit. The sensitivity of the kit was found to be 0.1 ng. Our validation process involved the examination of 59 RNA mixtures, 60 body fluids mixtures, and 20 casework samples, which further established the reliability of the kit. Furthermore, we constructed five classifiers that can handle single-body fluids and mixtures using this kit. The classifiers output possibility values and identify the specific body fluids of interest. Our results showed the reliability and suitability of the BFI kit, and the Random Forest classifier performed the best, with 94% precision. In conclusion, we developed an mRNA kit for BFI which can be a promising tool for forensic practice.

Optimizing Analytical Thresholds for Low-Template DNA Analysis: Insights from Multi-Laboratory Negative Controls.

When analyzing challenging samples, such as low-template DNA, analysts aim to maximize information while minimizing noise, often by adjusting the analytical threshold (AT) for optimal results. A potential approach involves calculating the AT based on the baseline signal distribution in electrophoresis results. This study investigates the impact of reagent kits, testing quarters, environmental conditions, and amplification cycles on baseline signals using historical records and experimental data on low-template DNA. Variations in these aspects contribute to differences in baseline signal patterns. Analysts should remain vigilant regarding routine instrument maintenance and reagent replacement, as these may affect baseline signals. Prompt analysis of baseline status and tailored adjustments to ATs under specific laboratory conditions are advised. A comparative analysis of published methods for calculating the optimal AT from a negative signal distribution highlighted the efficiency of utilizing baseline signals to enhance forensic genetic analysis, with the exception of extremely low-template samples and high-amplification cycles. Moreover, a user-friendly program for real-time analysis was developed, enabling prompt adjustments to ATs based on negative control profiles. In conclusion, this study provides insights into baseline signals, aiming to enhance genetic analysis accuracy across diverse laboratories. Practical recommendations are offered for optimizing ATs in forensic DNA analysis.

Single-nucleus transcriptomic mapping of blast-induced traumatic brain injury in mice hippocampus.

As a significant type of traumatic brain injury (TBI), blast-induced traumatic brain injury (bTBI) frequently results in severe neurological and psychological impairments. Due to its unique mechanistic and clinical features, bTBI presents diagnostic and therapeutic challenges compared to other TBI forms. The hippocampus, an important site for secondary injury of bTBI, serves as a key niche for neural regeneration and repair post-injury, and is closely associated with the neurological outcomes of bTBI patients. Nonetheless, the pathophysiological alterations of hippocampus underpinning bTBI remain enigmatic, and a corresponding transcriptomic dataset for research reference is yet to be established. In this investigation, the single-nucleus RNA sequencing (snRNA-seq) technique was employed to sequence individual hippocampal nuclei of mice from bTBI and sham group. Upon stringent quality control, gene expression data from 17,278 nuclei were obtained, with the dataset's reliability substantiated through various analytical methods. This dataset holds considerable potential for exploring secondary hippocampal injury and neurogenesis mechanisms following bTBI, with important reference value for the identification of specific diagnostic and therapeutic targets for bTBI.

An MPS-Based 50plex Microhaplotype Assay for Forensic DNA Analysis.

Microhaplotypes (MHs) are widely accepted as powerful markers in forensic studies. They have the advantage of both short tandem repeats (STRs) and single nucleotide polymorphisms (SNPs), with no stutter and amplification bias, short fragments and amplicons, low mutation and recombination rates, and high polymorphisms. In this study, we constructed a panel of 50 MHs that are distributed on 21 chromosomes and analyzed them using the Multiseq multiple polymerase chain reaction (multi-PCR) targeted capture sequencing protocol based on the massively parallel sequencing (MPS) platform. The sizes of markers and amplicons ranged between 11-81 bp and 123-198 bp, respectively. The sensitivity was 0.25 ng, and the calling results were consistent with Sanger sequencing and the Integrative Genomics Viewer (IGV). It showed measurable polymorphism among sequenced 137 Southwest Chinese Han individuals. No significant deviations in the Hardy-Weinberg equilibrium (HWE) and linkage disequilibrium (LD) were found at all MHs after Bonferroni correction. Furthermore, the specificity was 1:40 for simulated two-person mixtures, and the detection rates of highly degraded single samples and mixtures were 100% and 93-100%, respectively. Moreover, animal DNA testing was incomplete and low depth. Overall, our MPS-based 50-plex MH panel is a powerful forensic tool that provides a strong supplement and enhancement for some existing panels.

Development of specific and rapid detection of human DNA by recombinase polymerase amplification assay for forensic analysis.

The determination of human-derived samples is very important in forensic investigations and case investigation in order to determine vital information on the suspect and the case. In this study, we established a recombinase polymerase amplification (RPA) assay for rapid identification of human-derived components. The sensitivity of the assay was 0.003125 ng, with excellent species specificity, and human-derived DNA could be detected in the presence of non-human-derived components at a ratio of 1:1000. Moreover, the RPA assay had a strong tolerance to inhibitors, in the presence of 800 ng/µL humic acid, 400 ng/µL tannic acid, and 8000 ng/µL collagen. In forensic investigation, common body fluids (blood, saliva, semen, vaginal secretions) are all applicable, and the presence of DNA can be detected from samples after simple alkaline lysis, which greatly shortens the detection time. Four simulation and case samples (aged bones, aged bloodstains, hair, touch DNA) were also successfully applied. The above research results show that the RPA assay constructed in this study can be fully applied to forensic medicine to provide high sensitivity and applicability detection methods.

Single-nucleus profiling of adult mice sub-ventricular zone after blast-related traumatic brain injury.

Explosive blast-related traumatic brain injuries (bTBI) are common in war zones and urban terrorist attacks. These bTBIs often result in complex neuropathologic damage and neurologic complications. However, there is still a lack of specific strategies for diagnosing and/or treating bTBIs. The sub-ventricular zone (SVZ), which undergoes adult neurogenesis, is critical for the neurological maintenance and repair after brain injury. However, the cellular responses and mechanisms that trigger and modulate these activities in the pathophysiological processes following bTBI remain poorly understood. Here we employ single-nucleus RNA-sequencing (snRNA-seq) of the SVZ from mice subjected to a bTBI. This data-set, including 15272 cells (7778 bTBI and 7494 control) representing all SVZ cell types and is ideally suited for exploring the mechanisms underlying the pathogenesis of bTBIs. Additionally, it can serve as a reference for future studies regarding the diagnosis and treatment of bTBIs.

Intermittent fasting ameliorates neuronal ferroptosis and cognitive impairment in mice after traumatic brain injury.

Ferroptosis, a newly characterized form of programmed cell death that results from lipid peroxidation and mitochondrial dysfunction, has been demonstrated to be involved in the pathogenesis of traumatic brain injury (TBI). Scientific evidence has shown that intermittent fasting (IF) reduces both the lipid peroxidation and the mitochondrial dysfunction, raising the question of whether IF affects the ferroptosis induced by TBI. Here, based on an established TBI animal model, we examine the effects of IF on the activation of ferroptosis pathway as well as related outcomes. We uncovered that a 1-mo IF elevated the protective Gpx4 and Hspb1 expression, and partly abolished the increase of Nfe2l2, Slc7a11, Alox8, Steap3, and Nox2 in the cortex, which were induced by TBI. Furthermore, the characteristic cellular damage induced by ferroptosis was alleviated by IF, as revealed by Perls' Prussian blue staining, Nissl staining, and transmission electron microscope examination. Consistently, we examined the outcomes of mice subjected to TBI and found an improved cognitive function of the IF mice. In sum, our study demonstrated, to our knowledge for the first time, that a 1-mo IF regimen partly ameliorates ferroptosis in the cortex of mice subjected to TBI, which potentially contributes to a lessening of cognitive impairment.

Corrigendum: A novel SNP-STR system based on a capillary electrophoresis platform.

[This corrects the article DOI: 10.3389/fgene.2021.636821.].