Recent advances and application of whole genome amplification in molecular diagnosis and medicine

A safety and absolute activity measurement method for Phi29 DNA polymerase based on chemiluminescent detection of dATP consumption

BACKGROUND

Phi29 DNA polymerase serves as a cornerstone enzyme in molecular biology, enabling critical applications such as rolling-circle amplification, multiple strand-displacement amplification, and single-molecule real-time sequencing. Despite its widespread use, traditional methods for assessing its activity-including radioactive labeling and fluorescence-based quantification-suffer from limitations such as operational complexity, low precision, and safety risks. These challenges have hindered standardized quality control in both academic and industrial settings.

RESULTS

To address these limitations, we developed a chemiluminescence-based absolute quantitation method that directly measures dATP consumption during polymerization. This method streamlines operational workflows by eliminating the need for multi-step purification procedures or specialized equipment, enabling the quantification of Phi29 DNA polymerase activity within 2 h. It demonstrates robust linearity and sensitivity across a broad dynamic range (25-200 μg/mL), while employing chemiluminescence-based detection of dATP to replace 3H-labeled dTTP, thereby eliminating biohazard risks associated with radioactive materials and enhancing feasibility for routine laboratory implementation.

SIGNIFICANCE

This method introduces a novel approach for determining DNA polymerase activity by pioneering the correlation between dATP stoichiometry and enzymatic activity. It expands the applicability of activity assays to routine molecular biology laboratories, enabling rapid inter-batch consistency testing in commercial enzyme production. This advancement establishes a new benchmark for polymerase quality control.

Microbiome and Microbial Profiling of Arctic Snow Using Whole Genome Sequencing, Psychrophilic Culturing, and Novel Sampling Techniques

Recent advances in massively parallel DNA sequencing have enabled researchers to study new areas of extreme environments. Of particular interest to many researchers are areas of the Arctic that have yet to be comprehensively examined using DNA techniques. These modern approaches to microbial profiling provide new critical data on systems biology not yet seen before from Arctic samples. The discovery of new microbes, microbial biochemical pathways, and biosynthetic gene clusters are critically important when characterizing the Arctic snow microbiome and can provide insights to discovering valuable biosynthetic gene clusters. In this study, 2 L of snow was collected from 15 sites 12 km east outside of Ilulissat, Greenland, using DNA-free sterile techniques. Snow was allowed to melt and immediately concentrated using the InnovaPrep CP sample concentrator. Whole genome DNA sequencing was performed on extracts using both Illumina and Nanopore sequencing as well as psychrophilic culturing. Individual cultures were also sequenced to determine whole genome content and species identity. The results showed a wide-ranging microbiome across the snow fields, including bacteria, yeast, and fungi, with Granulicella, Methylobabcterium, Nostoc, Sphingomonas, and Streptomyces being consistently detected at higher levels across the majority of sites and sequencing platforms, while Belnapia, Chlorogloea, Hymenobacter, Mesorhizobium, Narcardioides, Pseudomonas, Pseudonocardia, Roseomonas, and Solirubrobacter at comparatively lower abundances. The results of culture data for snow sites reveal Pseudomanas sp., Pseudomonas fluorescens Group, unknown Microbacteriaceae sp., Variovorax sp., Robbsia andropogonis, and low concentrations of Aureobasidium sp., Stylodothis sp., Sphingomonas sp., Hymenobacter sp., Caballeronia sordidicola, and two unknown species of yeast and one unknown species of bacteria.

Comprehensive comparison of the third-generation sequencing tools for bacterial 6mA profiling

DNA N6-methyladenine (6mA) serves as an intrinsic and principal epigenetic marker in prokaryotes, impacting various biological processes. To date, limited advanced sequencing technologies and analyzing tools are available for bacterial DNA 6mA. Here, we evaluate eight tools designed for the 6mA identification or de novo methylation detection. This assessment includes Nanopore (R9 and R10), Single-Molecule Real-Time (SMRT) Sequencing, and cross-reference with 6mA-IP-seq and DR-6mA-seq. Our multi-dimensional evaluation report encompasses motif discovery, site-level accuracy, single-molecule accuracy, and outlier detection across six bacteria strains. While most tools correctly identify motifs, their performance varies at single-base resolution, with SMRT and Dorado consistently delivering strong performance. Our study indicates that existing tools cannot accurately detect low-abundance methylation sites. Additionally, we introduce an optimized method for advancing 6mA prediction, which substantially improves the detection performance of Dorado. Overall, our study provides a robust and detailed examination of computational tools for bacterial 6mA profiling, highlighting insights for further tool enhancement and epigenetic research.

Whole-genome amplification as a tool to improve bacterial detection by PCR in microbiological samples after endodontic treatment

Introduction

Microorganisms have an important role in the pathogenesis of endodontic disease. Significant advances have been made to increase the sensitivity of microbial detection, identification and enumeration in endodontic samples. The aim of the present study is to compare culture and whole-genome amplification (WGA) followed by PCR assays in the detection of bacteria before and after chemical mechanical preparation (CMP) of root canals.

Methods

Ten uniradicular teeth with primary endodontic infections were analyzed. Microbiological samples were collected before and after CMP using paper points, which were separated into two groups: (i) culture assay samples were plated onto Brucella agar with 5% defibrinated sheep's blood, menadione and hemin and incubated anaerobically for 14 days at 36°C; (ii) DNA was extracted from molecular assay samples and subject to WGA by isothermal strand displacement with Phi29 DNA polymerase followed by PCR to determine the presence of bacteria.

Results

In both assays, samples before CMP showed the presence of bacteria in all 10 teeth. After CMP, however, bacterial detection differed in the assays performed (p = 0.0198). The presence of bacteria was detected in 70% (7 of 10) of the samples by WGA followed by PCR, where only 10% (1 of 10) had demonstrated bacterial growth in the culture method.

Conclusion

The combination of WGA followed by PCR increased the detection of microorganisms from root canal samples after endodontic treatment using NaOCl as a CMP irrigant. So this combination of techniques can represent an important tool to improve the detection of microorganisms in endodontic research.

From Conventional Detection to Point-of-care Tests (POCT) Method for Pediatric Respiratory Infections Diagnosis: A Systematic Review

Bacterial respiratory infections pose significant health risks to children, particularly infants susceptible to upper respiratory tract infections (URTIs). The COVID-19 pandemic has further exacerbated the prevalence of these infections, with pathogens such as Mycoplasma pneumoniae, Streptococcus pneumoniae, Legionella pneumophila, Staphylococcus aureus, Haemophilus influenzae, and Klebsiella species commonly implicated in pediatric cases. The critical need for accurate and timely detection of these bacterial agents has highlighted the importance of advanced diagnostic techniques, including multiplex real-time PCR, in clinical practice. Multiplex real-time polymerase chain reaction (PCR) offers several advantages, including rapid results, high sensitivity, and specificity. By accelerating the diagnostic process, this approach enables early intervention and targeted treatment, ultimately improving patient outcomes. In addition to PCR technologies, rapid and point-of-care testing (POCT) play a crucial role in the prompt diagnosis of bacterial respiratory infections. These tests are designed to be user-friendly, sensitive, and deliver quick results, making them particularly valuable in urgent clinical settings. POCT tests are often categorized into two main groups: those aimed at determining the cause of infection and those focused on confirming the presence of specific pathogens. By utilizing POCT, healthcare providers can make rapid and informed treatment decisions, leading to more effective management of bacterial respiratory infections in children. As the medical community continues to explore innovative diagnostic approaches, the integration of molecular and rapid testing methods offers significant promise in the realm of bacterial respiratory infections. By adopting these cutting-edge technologies, healthcare professionals can enhance their ability to accurately diagnose these infections, tailor treatment strategies, and ultimately improve patient care.

Preimplantation genetic testing for four families with severe combined immunodeficiency: Three unaffected livebirths

PURPOSE

Severe combined immunodeficiency (SCID) is a set of rare monogenic inherited diseases that together represent the most severe form of the primary immunodeficiency disease phenotype. Preimplantation genetic testing for monogenic defects (PGT-M) is an effective reproductive technology strategy to prevent disease-causing gene mutations from being transmitted to offspring. The aim of this study was to report the use of PGT-M strategy based on karyomapping in four families to avoid the birth of SCID children.

METHODS

Four couples underwent the PGT-M strategy due to SCID. The strategy of PGT-M started with a biopsy of the trophectoderm cells of embryos, and the whole genome was amplified by multiple replacement amplification (MDA). Then, the single nucleotide polymorphisms (SNPs) in the region upstream and downstream of the mutation site were subsequently identified via karyomapping, and the results were analyzed via SNPs linkage analysis. The aneuploids of the embryos were identified simultaneously. Finally, prenatal amniocentesis was used to verify the validity of the PGT-M results.

RESULTS

We identified three novel variants (case1: IL2RG c.720_726delGAGCCAC; case 3: RAG2 c.770 C > T; and case 4: LIG4 c.1347 A > T). All four couples with SCID pathogenic gene mutations were subjected to karyomapping linkage analysis, and embryos with the pathogenic gene mutation were successfully identified. Euploid blastocysts without pathogenic alleles were transplanted, and healthy offspring were ultimately born. Prenatal diagnosis also confirmed the validity of our results.

CONCLUSION

This study revealed that karyomapping is an efficient approach for identifying SCID. Through PGT-M with karyomapping linkage analysis, healthy babies were born to families carrying mutations in the SCID pathogenic gene.

Combining single-cell analysis and molecular docking techniques to construct a prognostic model for colon adenocarcinoma and uncovering inhibin subunit βb as a novel therapeutic target

Background

Colon adenocarcinoma (COAD) is a malignancy with a high mortality rate and complex biological characteristics and heterogeneity, which poses challenges for clinical treatment. Anoikis is a type of programmed cell death that occurs when cells lose their attachment to the extracellular matrix (ECM), and it plays a crucial role in tumor metastasis. However, the specific biological link between anoikis and COAD, as well as its mechanisms in tumor progression, remains unclear, making it a potential new direction for therapeutic strategy research.

Methods

We employed transcriptomic data and clinical information from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) to pinpoint differentially expressed anoikis-related genes (ARGs) in COAD. Using Cox proportional hazards models and Lasso regression analysis, we developed a prognostic signature derived from these ARGs. We also investigated the roles and interactions of these genes in the tumor microenvironment by analyzing single-cell RNA sequencing data. Additionally, we employed molecular docking techniques to evaluate the potential of inhibin subunit beta B (INHBB) as therapeutic targets and to assess the binding affinity of candidate drugs. Finally, we used gene knockout techniques to silence the key gene INHBB and explored its biological functions in vitro.

Results

In our study, by analyzing the expression differences of ARGs, we successfully classified patients with COAD. Kaplan-Meier survival analysis demonstrated that patients with elevated risk scores experienced poorer prognosis, a finding that was confirmed in both the training and validation cohorts. Additionally, immune infiltration analysis revealed a notable increase in immune cell presence within the tumor microenvironment of high-risk patients. Molecular docking identified potential drug candidates with high binding affinity to INHBB, including risperidone. Furthermore, in vitro experiments with INHBB showed that downregulation of its expression in COAD cell lines significantly reduced cellular viability and migration capacity.

Conclusion

In summary, our research, based on the expression characteristics of ARGs, provides new insights into the precise classification, prognosis assessment, and identification of potential therapeutic targets in COAD. It also validates the key role of INHBB in the progression of COAD, establishing the foundation for future personalized treatment strategies.

Isothermal Detection Methods for Fungal Pathogens in Closed Environment Agriculture

Closed environment agriculture (CEA) is rapidly gaining traction as a sustainable option to meet global food demands while mitigating the impacts of climate change. Fungal pathogens represent a significant threat to crop productivity in CEA, where the controlled conditions can inadvertently foster their growth. Historically, the detection of pathogens has largely relied on the manual observation of signs and symptoms of disease in the crops. These approaches are challenging at large scale, time consuming, and often too late to limit crop loss. The emergence of fungicide resistance further complicates management strategies, necessitating the development of more effective diagnostic tools. Recent advancements in technology, particularly in molecular and isothermal diagnostics, offer promising tools for the early detection and management of fungal pathogens. Innovative detection methods have the potential to provide real-time results and enhance pathogen management in CEA systems. This review explores isothermal amplification and other new technologies in detection of fungal pathogens that occur in CEA.

Multiple Displacement Amplification Facilitates SMRT Sequencing of Microscopic Animals and the Genome of the Gastrotrich Lepidodermella squamata (Dujardin 1841)

Obtaining adequate DNA for long-read genome sequencing remains a roadblock to producing contiguous genomes from small-bodied organisms, hindering understanding of phylogenetic relationships and genome evolution. Multiple displacement amplification leverages Phi29 DNA polymerase to produce micrograms of DNA from picograms of input. However, multiple displacement amplification's inherent biases in amplification related to guanine and cytosine (GC) content, repeat content and chimera production are a problem for long-read genome assembly, which has been little investigated. We explored the utility of multiple displacement amplification for generating template DNA for High Fidelity (HiFi) sequencing directly from living cells of Caenorhabditis elegans (Nematoda) and Lepidodermella squamata (Gastrotricha) containing one order of magnitude less DNA than required for the PacBio Ultra-Low DNA Input Workflow. High Fidelity sequencing of libraries prepared from multiple displacement amplification products resulted in highly contiguous and complete genomes for both C. elegans (102 Mbp assembly; 336 contigs; N50 = 868 kbp; L50 = 39; BUSCO_nematoda_nucleotide: S:96.1%, D:2.8%) and L. squamata (122 Mbp assembly; 157 contigs; N50 = 3.9 Mbp; L50 = 13; BUSCO_metazoa_nucleotide: S:80.8%, D:2.8%). Coverage uniformity for reads from multiple displacement amplification DNA (Gini Index: 0.14, normalized mean across all 100 kbp blocks: 0.49) and reads from pooled nematode DNA (Gini Index: 0.16, normalized mean across all 100 kbp blocks: 0.49) proved similar. Using this approach, we sequenced the genome of the microscopic invertebrate L. squamata (Gastrotricha), the first of its phylum. Using the newly sequenced genome, we infer Gastrotricha's long-debated phylogenetic position as the sister taxon of Platyhelminthes and conduct a comparative analysis of the Hox cluster.

From Cell to Gene: Deciphering the Mechanism of Heart Failure With Single-Cell Sequencing

Heart failure (HF) is a prevalent cardiovascular disease with significant morbidity and mortality rates worldwide. Due to the intricate structure of the heart, diverse cell types, and the complex pathogenesis of HF, further in-depth investigation into the underlying mechanisms  is required. The elucidation of the heterogeneity of cardiomyocytes and the intercellular communication network is particularly important. Traditional high-throughput sequencing methods provide an average measure of gene expression, failing to capture the "heterogeneity" between cells and impacting the accuracy of gene function knowledge. In contrast, single-cell sequencing techniques allow for the amplification of the entire genome or transcriptome at the individual cell level, facilitating the examination of gene structure and expression with unparalleled precision. This approach offers valuable insights into disease mechanisms, enabling the identification of changes in cellular components and gene expressions during hypertrophy associated with HF. Moreover, it reveals distinct cell populations and their unique roles in the HF microenvironment, providing a comprehensive understanding of the cellular landscape that underpins HF pathogenesis. This review focuses on the insights provided by single-cell sequencing techniques into the mechanisms underlying HF and discusses the challenges encountered in current cardiovascular research.

GoEnrich: creating high quality genomic DNA resources from limited voucher specimen tissues or museum specimens of at-risk species for conservation-friendly use in the validation of environmental DNA assays

OBJECTIVE

Environmental DNA (eDNA) methods are crucial for monitoring populations, particularly rare and cryptic species. For confident eDNA application, rigorous assay validation is required including specificity testing with genomic DNA (gDNA). However, this critical step is often difficult to achieve as obtaining fresh tissue samples from at-risk species can be difficult, highly limited, or impossible. Natural history museum collections could serve as a valuable and ethical voucher specimen resource for eDNA assay validation. The present study demonstrates the effectiveness of whole genome amplification (WGA) in providing enough gDNA to assemble high quality mitogenomes from which robust targeted eDNA assays can be designed.

RESULTS

Using fresh and historical museum tissue samples from six species spanning fish, birds, and mammals, we successfully developed a WGA method with an average yield of 380 to 1,268 ng gDNA per 20 µL reaction. This gDNA was used for whole genome shotgun sequencing and subsequent assembly of high quality mitogenomes using mtGrasp. These mitogenomes were then used to develop six new robust, targeted quantitative real time polymerase chain reaction-based eDNA assays and 200 ng WGA-enriched yielded satisfactory Cq values and near 100% detection frequencies for all assays tested. This approach offers a cost-effective and non-invasive alternative, streamlining eDNA research processes and aiding in conservation efforts.

Endonuclease Q as a robust enhancer for nucleic acid amplification

Isothermal nucleic acid amplification techniques are attracting increasing attention in molecular diagnosis and biotechnology. However, most existing techniques are complicated by the need for intricate primer design and numerous enzymes and primers. Here, we have developed a simple method, termed NAQ, that employs adding both endonuclease Q (EndoQ) and dUTP/dITP to conventional rolling circle amplification reactions to increase DNA amplification. NAQ does not require intricate primer design or DNA sequence-specific enzymes, and existing isothermal amplification techniques could be readily adapted to include both EndoQ and dUTP/dITP.

Advancements in magnetic nanoparticle-based biosensors for point-of-care testing

The significance of point-of-care testing (POCT) in early clinical diagnosis and personalized patient care is increasingly recognized as a crucial tool in reducing disease outbreaks and improving patient survival rates. Within the realm of POCT, biosensors utilizing magnetic nanoparticles (MNPs) have emerged as a subject of substantial interest. This review aims to provide a comprehensive evaluation of the current landscape of POCT, emphasizing its growing significance within clinical practice. Subsequently, the current status of the combination of MNPs in the Biological detection has been presented. Furthermore, it delves into the specific domain of MNP-based biosensors, assessing their potential impact on POCT. By combining existing research and spotlighting pivotal discoveries, this review enhances our comprehension of the advancements and promising prospects offered by MNP-based biosensors in the context of POCT. It seeks to facilitate informed decision-making among healthcare professionals and researchers while also promoting further exploration in this promising field of study.

On the origin of bird's nest fungi: Phylogenomic analyses of fungi in the Nidulariaceae (Agaricales, Basidiomycota)

Nidulariaceae, also known as bird's nest fungi, is an understudied group of mushroom-forming fungi. The common name is derived from their nest-like morphology. Bird's nest fungi are ubiquitous wood decomposers or saprobes on dung. Recent studies showed that species in the Nidulariaceae form a monophyletic group with five sub-clades. However, phylogenetic relationships among genera and placement of Nidulariaceae are still unclear. We present phylogenomic analyses of bird's nest fungi and related Agaricales fungi to gain insight into the evolution of Nidulariaceae. A species tree with 17 newly generated genomes of bird's nest fungi and representatives from all major clades of Agaricales was constructed using 1044 single-copy genes to explore the intergeneric relationships and pinpoint the placement of Nidulariaceae within Agaricales. We corroborated the hypothesis that bird's nest fungi are sister to Squamanitaceae, which includes mushroom-shaped fungi with a stipe and pileus that are saprobes and mycoparasites. Lastly, stochastic character mapping of discrete traits on phylogenies (SIMMAP) suggests that the ancestor of bird's nest fungi likely possessed an evanescent, globose peridium without strings attaching to the spore packets (funiculi). This analysis suggests that the funiculus was gained twice and that the persistent, cupulate peridium form was gained at least four times and lost once. However, alternative coding schemes and datasets with a wider array of Agaricales produced conflicting results during ancestral state reconstruction, indicating that there is some uncertainty in the number of peridium transitions and that taxon sampling may significantly alter ancestral state reconstructions. Overall, our results suggest that several key morphological characters of Nidulariaceae have been subject to homoplasy.

CyanoStrainChip: A Novel DNA Microarray Tool for High-Throughput Detection of Environmental Cyanobacteria at the Strain Level

Detecting cyanobacteria in environments is an important concern due to their crucial roles in ecosystems, and they can form blooms with the potential to harm humans and nonhuman entities. However, the most widely used methods for high-throughput detection of environmental cyanobacteria, such as 16S rRNA sequencing, typically provide above-species-level resolution, thereby disregarding intraspecific variation. To address this, we developed a novel DNA microarray tool, termed the CyanoStrainChip, that enables strain-level comprehensive profiling of environmental cyanobacteria. The CyanoStrainChip was designed to target 1277 strains; nearly all major groups of cyanobacteria are included by implementing 43,666 genome-wide, strain-specific probes. It demonstrated strong specificity by in vitro mock community experiments. The high correlation (Pearson's R > 0.97) between probe fluorescence intensities and the corresponding DNA amounts (ranging from 1-100 ng) indicated excellent quantitative capability. Consistent cyanobacterial profiles of field samples were observed by both the CyanoStrainChip and next-generation sequencing methods. Furthermore, CyanoStrainChip analysis of surface water samples in Lake Chaohu uncovered a high intraspecific variation of abundance change within the genus Microcystis between different severity levels of cyanobacterial blooms, highlighting two toxic Microcystis strains that are of critical concern for Lake Chaohu harmful blooms suppression. Overall, these results suggest a potential for CyanoStrainChip as a valuable tool for cyanobacterial ecological research and harmful bloom monitoring to supplement existing techniques.

Liquid biopsy for precision diagnostics and therapeutics

Liquid biopsy (LB) has emerged as a highly promising and non-invasive diagnostic approach, particularly in the field of oncology, and has garnered interest in various medical disciplines. This technique involves the examination of biomolecules released into physiological fluids, such as urine samples, blood, and cerebrospinal fluid (CSF). The analysed biomolecules included circulating tumour DNA (ctDNA), circulating tumour cells (CTCs), cell-free DNA (cfDNA), exosomes, and other cell-free components. In contrast to conventional tissue biopsies, LB provides minimally invasive diagnostics, offering invaluable insights into tumor characteristics, treatment response, and early disease detection. This Review explores the contemporary landscape of technologies and clinical applications in the realm of LB, with a particular emphasis on the isolation and analysis of ctDNA and/or cfDNA. Various methodologies have been employed, including droplet digital polymerase chain reaction (DDP), BEAMing (beads, emulsion, amplification, and magnetics), TAm-Seq (tagged-amplicon deep sequencing), CAPP-Seq (cancer personalized profiling by deep sequencing), WGBS-Seq (whole genome bisulfite sequencing), WES (whole exome sequencing), and WGS (whole-genome sequencing). Additionally, CTCs have been successfully isolated through biomarker-based cell capture, employing both positive and negative enrichment strategies based on diverse biophysical and other inherent properties. This approach also addresses challenges and limitations associated with liquid biopsy techniques, such as sensitivity, specificity, standardization and interpretability of findings. This review seeks to identify the current technologies used in liquid biopsy samples, emphasizing their significance in identifying tumor markers for cancer detection, prognosis, and treatment outcome monitoring.

Genomic characterization of three bacterial isolates antagonistic to the pea root rot pathogen Aphanomyces euteiches

Microorganisms living in soil and rhizosphere or inside plants can promote plant growth and health. Genomic characterization of beneficial microbes could shed light on their special features. Through extensive field survey across Saskatchewan, Canada, followed by in vitro and greenhouse characterization, we identified several bacterial isolates antagonistic to pea root rot pathogen Aphanomyces euteiches. In this study, the genomes of three isolates-Pseudomonas sp. rhizo 66 (PD-S66), Pseudomonas synxantha rhizo 25 (Ps-S25), and Serratia sp. root 2 (TS-R2)-were sequenced, assembled, and annotated. Genome size of PD-S66 was 6 279 416 bp with 65 contigs, 59.32% GC content, and 5653 predicted coding sequences (CDS). Genome size of Ps-S25 was 6 058 437 bp with 66 contigs, a GC content of 60.08%, and 5575 predicted CDS. The genome size of TS-R2 was 5 282 152 bp, containing 26 contigs, a GC content of 56.17%, and 4956 predicted CDS. For the identification of the isolates, digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values were determined, which confirmed PD-S66 and TS-R2 as potential new species, belonging to Pseudomonas and Serratia genera, respectively, while Ps-S25 belongs to species Pseudomonas synxantha. Biosynthetic gene clusters were predicted using antiSMASH. The genomic data provided insight into the genetics and biochemical pathways supporting the antagonistic activity against A. euteiches of these isolates.

Genetic Analysis of Vanishing Twin Syndrome Using Next-Generation Sequencing and Short Tandem Repeat Analysis: A Case Report and Literature Review

Vanishing twin syndrome (VTS) refers to the spontaneous reduction of a fetus during multiple pregnancies, resulting in its invisibility during gestation. Vanishing twin syndrome is commonly identified through ultrasonographic examination in early pregnancy; nonetheless, the genetic causes of VTS are rarely detected. This report aimed to investigate the feasibility of genetic testing for VTS using low-coverage whole-genome sequencing and short tandem repeat (STR) analysis. We report a 39-year-old woman who underwent in vitro fertilization and conceived dichorionic diamniotic twins. The heartbeat of 1 fetus ceased at 11 weeks, leading to a diagnosis of VTS, whereas the surviving fetus developed normally and was delivered at full term. Placental examination revealed a rudimentary gestational sac adjacent to the placenta that correlated with the vanished fetus. Chorionic tissues were collected from the placenta of the live-born infant and the rudimentary gestational sac that was considered to have originated from the vanished fetus. Genetic testing of chorionic tissues from the gestational sac and placenta showed that both fetuses were monozygotic twins with a normal 46, XY male karyotype. However, a triallelic pattern at the Penta E locus was identified in the vanished fetus on STR analysis, which was a unique genetic characteristic. This report highlights the feasibility of genetic testing for VTS, despite the unclear relationship between the identified genetic pattern and the vanished fetus.

Comprehensive application of multiple molecular diagnostic techniques in pre-implantation genetic testing for monogenic

BACKGROUND

Pre-implantation genetic testing for monogenic disorders (PGT-M) is an effective approach to reducing the incidence of birth defects by preventing the transmission of inherited diseases to offspring. However, there are still controversies regarding the detection methods and transplantation of embryos. This paper aims to evaluate the effectiveness of different detection technologies applied to PGT-M through a retrospective analysis of clinical detection data.

METHODS

The carrier status of pathogenic mutations and chromosomal copy number variants (CNVs) in 892 embryos was characterized using next-generation sequencing (NGS), single-nucleotide polymorphism (SNP) array, and PCR-based detection technologies. Clinical data from PGT-M cases were retrospectively analyzed to assess the effectiveness of these detection methods in identifying genetic abnormalities in embryos.

RESULTS

A total of 829 embryos were analyzed, with 63 being unsuccessful. Our study revealed that the success rate of detecting deletional mutations using Gap-PCR 84.9%, which is lower than that of SNP array (98.7%) and NGS (92.5%). However, no significant difference was observed when detecting point mutations using any of the methods. These findings suggest that, when detecting deletional mutations, SNP array and NGS are more suitable choices compared to Gap-PCR. While SNP array may have a lower resolution and success rate (80.5%) in analyzing CNVs compared to NGS (95.5%), it may still be useful for revealing certain abnormal types.

CONCLUSION

In conclusion, this study found that SNP analysis is advantageous for identifying polygenic and deletional mutations, whereas NGS is more cost-efficient for detecting common monogenic diseases. Additionally, SNP-based haplotyping and PCR-based direct detection of mutations can be used together to enhance the accuracy and success rates of PGT-M. Our findings offer valuable insights for PGT technicians in choosing suitable detection methods for patients.

Recombinase Polymerase Amplification-Based Biosensors for Rapid Zoonoses Screening

Recent, outbreaks of new emergency zoonotic diseases have prompted an urgent need to develop fast, accurate, and portable screening assays for pathogen infections. Recombinase polymerase amplification (RPA) is sensitive and specific and can be conducted at a constant low temperature with a short response time, making it especially suitable for on-site screening and making it a powerful tool for preventing or controlling the spread of zoonoses. This review summarizes the design principles of RPA-based biosensors as well as various signal output or readout technologies involved in fluorescence detection, lateral flow assays, enzymatic catalytic reactions, spectroscopic techniques, electrochemical techniques, chemiluminescence, nanopore sequencing technologies, microfluidic digital RPA, and clustered regularly interspaced short palindromic repeats/CRISPR-associated systems. The current status and prospects of the application of RPA-based biosensors in zoonoses screening are highlighted. RPA-based biosensors demonstrate the advantages of rapid response, easy-to-read result output, and easy implementation for on-site detection, enabling development toward greater portability, automation, and miniaturization. Although there are still problems such as high cost with unstable signal output, RPA-based biosensors are increasingly becoming one of the most important means of on-site pathogen screening in complex samples involving environmental, water, food, animal, and human samples for controlling the spread of zoonotic diseases.

Advances in novel strategies for isolation, characterization, and analysis of CTCs and ctDNA

Over the past decade, the detection and analysis of liquid biopsy biomarkers such as circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA) have advanced significantly. They have received recognition for their clinical usefulness in detecting cancer at an early stage, monitoring disease, and evaluating treatment response. The emergence of liquid biopsy has been a helpful development, as it offers a minimally invasive, rapid, real-time monitoring, and possible alternative to traditional tissue biopsies. In resource-limited settings, the ideal platform for liquid biopsy should not only extract more CTCs or ctDNA from a minimal sample volume but also accurately represent the molecular heterogeneity of the patient's disease. This review covers novel strategies and advancements in CTC and ctDNA-based liquid biopsy platforms, including microfluidic applications and comprehensive analysis of molecular complexity. We discuss these systems' operational principles and performance efficiencies, as well as future opportunities and challenges for their implementation in clinical settings. In addition, we emphasize the importance of integrated platforms that incorporate machine learning and artificial intelligence in accurate liquid biopsy detection systems, which can greatly improve cancer management and enable precision diagnostics.

Improved single-cell genome amplification by a high-efficiency phi29 DNA polymerase

Single-cell genomic whole genome amplification (WGA) is a crucial step in single-cell sequencing, yet its low amplification efficiency, incomplete and uneven genome amplification still hinder the throughput and efficiency of single-cell sequencing workflows. Here we introduce a process called Improved Single-cell Genome Amplification (iSGA), in which the whole single-cell sequencing cycle is completed in a high-efficient and high-coverage manner, through phi29 DNA polymerase engineering and process engineering. By establishing a disulfide bond of F137C-A377C, the amplification ability of the enzyme was improved to that of single-cell. By further protein engineering and process engineering, a supreme enzyme named HotJa Phi29 DNA Polymerase was developed and showed significantly better coverage (99.75%) at a higher temperature (40°C). High single-cell genome amplification ability and high coverage (93.59%) were also achieved for commercial probiotic samples. iSGA is more efficient and robust than the wild-type phi29 DNA polymerase, and it is 2.03-fold more efficient and 10.89-fold cheaper than the commercial Thermo Scientific EquiPhi29 DNA Polymerase. These advantages promise its broad applications in large-scale single-cell sequencing.

DNA Polymerases for Whole Genome Amplification: Considerations and Future Directions

In the same way that specialized DNA polymerases (DNAPs) replicate cellular and viral genomes, only a handful of dedicated proteins from various natural origins as well as engineered versions are appropriate for competent exponential amplification of whole genomes and metagenomes (WGA). Different applications have led to the development of diverse protocols, based on various DNAPs. Isothermal WGA is currently widely used due to the high performance of Φ29 DNA polymerase, but PCR-based methods are also available and can provide competent amplification of certain samples. Replication fidelity and processivity must be considered when selecting a suitable enzyme for WGA. However, other properties, such as thermostability, capacity to couple replication, and double helix unwinding, or the ability to maintain DNA replication opposite to damaged bases, are also very relevant for some applications. In this review, we provide an overview of the different properties of DNAPs widely used in WGA and discuss their limitations and future research directions.

Spatiotemporal dissection of tumor microenvironment via in situ sensing and monitoring in tumor-on-a-chip

Real-time monitoring in the tumor microenvironment provides critical insights of cancer progression and mechanistic understanding of responses to cancer treatments. However, clinical challenges and significant questions remain regarding assessment of limited clinical tissue samples, establishment of validated, controllable pre-clinical cancer models, monitoring of static versus dynamic markers, and the translation of insights gained from in vitro tumor microenvironments to systematic investigation and understanding in clinical practice. State-of-art tumor-on-a-chip strategies will be reviewed herein, and emerging real-time sensing and monitoring platforms for on-chip analysis of tumor microenvironment will also be examined. The integration of the sensors with tumor-on-a-chip platforms to provide spatiotemporal information of the tumor microenvironment and the associated challenges will be further evaluated. Though optimal integrated systems for in situ monitoring are still in evolution, great promises lie ahead that will open new paradigm for rapid, comprehensive analysis of cancer development and assist clinicians with powerful tools to guide the diagnosis, prognosis and treatment course in cancer.

The Single-Cell Landscape of Intratumoral Heterogeneity and The Immunosuppressive Microenvironment in Liver and Brain Metastases of Breast Cancer

Distant metastasis remains the major cause of morbidity for breast cancer. Individuals with liver or brain metastasis have an extremely poor prognosis and low response rates to anti-PD-1/L1 immune checkpoint therapy compared to those with metastasis at other sites. Therefore, it is urgent to investigate the underlying mechanism of anti-PD-1/L1 resistance and develop more effective immunotherapy strategies for these patients. Using single-cell RNA sequencing, a high-resolution map of the entire tumor ecosystem based on 44 473 cells from breast cancer liver and brain metastases is depicted. Identified by canonical markers and confirmed by multiplex immunofluorescent staining, the metastatic ecosystem features remarkable reprogramming of immunosuppressive cells such as FOXP3+ regulatory T cells, LAMP3+ tolerogenic dendritic cells, CCL18+ M2-like macrophages, RGS5+ cancer-associated fibroblasts, and LGALS1+ microglial cells. In addition, PD-1 and PD-L1/2 are barely expressed in CD8+ T cells and cancer/immune/stromal cells, respectively. Interactions of the immune checkpoint molecules LAG3-LGALS3 and TIGIT-NECTIN2 between CD8+ T cells and cancer/immune/stromal cells are found to play dominant roles in the immune escape. In summary, this study dissects the intratumoral heterogeneity and immunosuppressive microenvironment in liver and brain metastases of breast cancer for the first time, providing insights into the most appropriate immunotherapy strategies for these patients.