Pathogenic mechanism and therapeutic intervention of impaired N7-methylguanosine (m7G) tRNA modification.

Mutations modification enzymes including the tRNA N7-methylguanosine (m7G) methyltransferase complex component WDR4 were frequently found in patients with neural disorders, while the pathogenic mechanism and therapeutic intervention strategies are poorly explored. In this study, we revealed that patient-derived WDR4 mutation leads to temporal and cell-type-specific neural degeneration, and directly causes neural developmental disorders in mice. Mechanistically, WDR4 point mutation disrupts the interaction between WDR4 and METTL1 and accelerates METTL1 protein degradation. We further uncovered that impaired tRNA m7G modification caused by Wdr4 mutation decreases the mRNA translation of genes involved in mTOR pathway, leading to elevated endoplasmic reticulum stress markers, and increases neural cell apoptosis. Importantly, treatment with stress-attenuating drug Tauroursodeoxycholate (TUDCA) significantly decreases neural cell death and improves neural functions of the Wdr4 mutated mice. Moreover, adeno-associated virus mediated transduction of wild-type WDR4 restores METTL1 protein level and tRNA m7G modification in the mouse brain, and achieves long-lasting therapeutic effect in Wdr4 mutated mice. Most importantly, we further demonstrated that both TUDCA treatment and WDR4 restoration significantly improve the survival and functions of human iPSCs-derived neuron stem cells that harbor the patient's WDR4 mutation. Overall, our study uncovers molecular insights underlying WDR4 mutation in the pathogenesis of neural diseases and develops two promising therapeutic strategies for treatment of neural diseases caused by impaired tRNA modifications.

[Systematic analysis on chemical constituents of Mori Cortex, mulberry root bark and its phellem layer based on HPLC-ESI-MS].

In this study, HPLC-ESI-MS and HPLC methods were established to explore the differences in the main chemical components and content of Mori Cortex with(mulberry root bark) and without(Mori Cortex) the phellem layer from both qualitative and quantitative aspects. The HPLC-ESI-MS method was used for quality analysis in positive and negative ion modes, and 33 compounds were identified in mulberry root bark, 22 compounds in Mori Cortex, and 26 compounds in phellem layer; mulberry root bark and Mori Cortex shared 22 components, and mulberry root bark has 11 unique compounds; Mori Cortex and its phellem layer shared 15 components, while Mori Cortex has 7 unique compounds. HPLC method was used to simultaneously determine 7 major constituents, including mulberroside A, chlorogenic acid, dihydromorin, oxyresveratrol, moracin O, kuwanon G, and kuwanon H, and the developed method showed good linearity(r>0.998 9) within the concentration range and the recoveries varied from 99.88% to 103.0%, and the RSD was 1.7%-2.9%. The HPLC results showed that the contents of the 7 compounds have great differences in 13 batches samples, compared with mulberry root bark, the contents of mulberroside A, chlorogenic acid, dihydromorin and moracin O of Mori Cortex were increased, while the contents of oxyresveratrol, kuwanon G and kuwanon H were decreased after peeling process. These results can provide a basis for the rationality and quality control of Mori Cortex required to remove the phellem layer.

The characteristics of pretreatment HIV-1 drug resistance in western Yunnan, China.

HIV-1 drug resistance can compromise the effectiveness of antiretroviral therapy (ART). A survey of pretreatment HIV-1 drug resistance (PDR) was conducted in Lincang Prefecture of Yunnan Province. From 372 people living with HIV/AIDS initiating ART for the first time during 2017-2018, 322 pol sequences were obtained, of which 11 HIV-1 strain types were detected. CRF08_BC (70.2%, 226/322) was the predominant strain, followed by URF strains (10.6%, 34/322). Drug resistance mutations (DRMs) were detected among 34.2% (110/322) of the participants. E138A/G/K/R (14.3%, 46/322) and V179E/D/T (13.7%, 47/322) were the predominant DRMs. Specifically, E138 mutations commonly occurred in CRF08_BC (19.9%, 45/226). Among the DRMs detected, some independently conferred resistance, such as K65R (1.6%, 5/322), Y188C/F/L (0.9%, 3/322), K103N (0.6%, 2/322) and G190A (0.3%, 1/322), which conferred high-level resistance. The prevalence of PDR was 7.5% (95% CI: 4.6-10.3%) and the prevalence of non-nucleotide reverse transcriptase inhibitor (NNRTI) resistance was 5.0% (95% CI: 2.6-7.4%), which is below the threshold (⩾10%) of initiating a public health response. In conclusion, HIV-1 genetic diversity and an overall moderate level of PDR prevalence were found in western Yunnan. PDR surveillance should be continually performed to decide whether a public health response to NNRTI resistance should be initiated.

Inhibition effect of polyvinyl chloride on ferrihydrite reduction and electrochemical activities of Geobacter metallireducens.

Geobacter metallireducens GS15, a model of dissimilatory iron-reducing bacteria, is the key regulator in biogeochemical iron cycling. How the emerging contaminant microplastics involved in the iron cycling are driven by microbes on the microscale remains unknown. Hence, the influences of two typical microplastics, polybutylene terephthalate-hexane acid (PBAT) and polyvinyl chloride (PVC), were explored on the activity of G. metallireducens GS15 with ferrihydrite or ferric citrate as the respective electron acceptors. The results showed that the iron (II) contents in PBAT- and PVC-treatment groups were 16.79 and 6.81 mM, respectively, at the end of the experiment. Compared with the PBAT-treatment group, scanning electron microscopy and energy dispersive spectrometery revealed that merely a small amount of iron-containing products covered the surface of PVC. Moreover, PBAT and PVC could both retard the electroactivity of G. metallireducens GS15 at the beginning of microbial fuel cell operation. On the basis of the results above, microplastic PVC might exhibit potential inhibition of the iron cycling process driven by G. metallireducens GS15 with ferrihydrite as the terminal electron acceptor. This study extended our understanding of the influence of the microplastics PBAT and PVC on microbially mediated biogeochemical iron cycling. The findings might have an important implication on the biogeochemical elements cycling in the ecosystem with the involvement of emerging contaminant microplastics.

Development of DNAzyme-based PCR signal cascade amplification for visual detection of Listeria monocytogenes in food.

Listeria monocytogenes is an important foodborne pathogen, and it can cause severe diseases. Rapid detection of L. monocytogenes is crucial to control this pathogen. A simple and robust strategy based on the cascade of PCR and G-quadruplex DNAzyme catalyzed reaction was used to detect L. monocytogenes. In the presence of hemin and the aptamer formed during PCR, the catalytic horseradish peroxidase-mimicking G-quadruplex DNAzymes allow the colorimetric responses of target DNA from L. monocytogenes. This assay can detect genomic DNA of L. monocytogenes specifically with as low as 50 pg/reaction with the naked eye. Through 20 pork samples assay, visual detection assay had the same results as conventional detection methods, and had a good performance. This is a powerful demonstration of the ability of G-quadruplex DNAzyme to be used for PCR-based assay with significant advantages of high sensitivity, low cost and simple manipulation over existing approaches and offers the opportunity for application in pathogen detection.

Development of a sensitive Luminex xMAP-based microsphere immunoassay for specific detection of Iris yellow spot virus.

BACKGROUND: Iris yellow spot virus (IYSV) is an Orthotospovirus that infects most Allium species. Very few approaches for specific detection of IYSV from infected plants are available to date. We report the development of a high-sensitive Luminex xMAP-based microsphere immunoassay (MIA) for specific detection of IYSV. RESULTS: The nucleocapsid (N) gene of IYSV was cloned and expressed in Escherichia coli to produce the His-tagged recombinant N protein. A panel of monoclonal antibodies (MAbs) against IYSV was generated by immunizing the mice with recombinant N protein. Five specific MAbs (16D9, 11C6, 7F4, 12C10, and 14H12) were identified and used for developing the Luminex xMAP-based MIA systems along with a polyclonal antibody against IYSV. Comparative analyses of their sensitivity and specificity in detecting IYSV from infected tobacco leaves identified 7F4 as the best-performed MAb in MIA. We then optimized the working conditions of Luminex xMAP-based MIA in specific detection of IYSV from infected tobacco leaves by using appropriate blocking buffer and proper concentration of biotin-labeled antibodies as well as the suitable ratio between the antibodies and the streptavidin R-phycoerythrin (SA-RPE). Under the optimized conditions the Luminex xMAP-based MIA was able to specifically detect IYSV with much higher sensitivity than conventional enzyme-linked immunosorbent assay (ELISA). Importantly, the Luminex xMAP-based MIA is time-saving and the whole procedure could be completed within 2.5 h. CONCLUSIONS: We generated five specific MAbs against IYSV and developed the Luminex xMAP-based MIA method for specific detection of IYSV in plants. This assay provides a sensitive, high-specific, easy to perform and likely cost-effective approach for IYSV detection from infected plants, implicating potential broad usefulness of MIA in plant virus diagnosis.

Inhibition of biofilm in Bacillus amyloliquefaciens Q-426 by diketopiperazines.

Biofilm formation can make significant effects on bacteria habits and biological functions. In this study, diketopiperazines (DKPs) produced by strain of Bacillus amyloliquefaciens Q-426 was found to inhibit biofilm formed in the gas-liquid interface. Four kinds of DKPs were extracted from B. amyloliquefaciens Q-426, and we found that 0.04 mg ml(-1) DKPs could obviously inhibit the biofilm formation of the strain. DKPs produced by B. amyloliquefaciens Q-426 made a reduction on extracellular polymeric substance (EPS) components, polysaccharides, proteins, DNAs, etc. Real-time PCR was performed to determine that whether DKPs could make an obvious effect on the expression level for genes related to biofilm formation in the strain. The relative expression level of genes tasA, epsH, epsG and remB which related to proteins, extracellular matrix, and polysaccharides, were downregulated with 0.04 mg ml(-1) DKPs, while the expression level of nuclease gene nuc was significantly upregulated. The quantitative results of the mRNA expression level for these genes concerted with the quantitative results on EPS levels. All of the experimental results ultimately indicated that DKPs could inhibit the biofilm formation of the strain B. amyloliquefaciens Q-426.

DNA-fueled molecular machine enables enzyme-free target recycling amplification for electronic detection of microRNA from cancer cells with highly minimized background noise.

The variations in microRNA (miRNA) expression levels can be useful biomarkers for the diagnosis of different cancers. In this work, on the basis of a new miRNA-triggered molecular machine for enzyme-free target recycling signal amplification, the development of a simple electronic sensor for highly sensitive detection of miRNA-21 from human breast cancer cells is described. The three-stand DNA duplex probes are self-assembled on the gold electrode surface to fabricate the sensor. The miRNA-21 target binds to the terminal toehold region of the probes, displaces one of the short strands through toehold-mediated strand displacement reactions, and exposes the secondary toehold region for subsequent hybridization with the methylene blue (MB)-modified DNA fuel strand, which further displaces both the miRNA-21 target and the other short strand to activate the operation of the molecular machine. As a result, the miRNA-21 target is cyclically reused, and many MB-DNA fuel strands are attached to the sensor surface, leading to a significantly amplified current response for sensitive detection of miRNA-21 down to 1.4 fM. The developed sensor also shows high sequence discrimination capability and can be used to monitor miRNA-21 expression levels in cancer cells. Moreover, this sensor avoids the involvement of any enzymes for target recycling amplification and features with highly minimized background noise for miRNA detection, which makes this method hold great potential for convenient monitoring of different miRNA biomarkers for early diagnosis of various cancers.

Aptamer pseudoknot-functionalized electronic sensor for reagentless and single-step detection of immunoglobulin E in human serum.

The development of electronic sensors with minimized usage of reagents and washing steps in the sensing protocols will significantly facilitate the detection of biomolecules. In this work, by using a new pseudoknot design of the aptamer probes, the construction of an electronic sensor for reagentless and single-step detection of immunoglobulin E (IgE) in human serum is described. The pseudoknot aptamer probes are self-assembled on the disposable electrode surface. The association of IgE with the aptamer probes leads to conformational changes of the pseudoknot aptamer structures and brings the redox-tags in close proximity to the electrode, resulting in amplified current response for monitoring IgE. The effects of the pseudoknot structure and the immobilization concentration of the aptamer probes on the sensor performance are evaluated. Under optimal conditions, the detection limit for IgE is estimated to be 60 pM. The sensor is also selective and can be employed to detect IgE in human serum samples. The developed sensor can achieve reagentless, washing-free and low-cost (with the disposable electrode) electrochemical detection of proteins, making this device a convenient sensing platform for the monitoring of different biomarkers when coupled with the appropriate aptamer probes.

Target-induced reconfiguration of DNA probes for recycling amplification and signal-on electrochemical detection of hereditary tyrosinemia type I gene.

By coupling target DNA-induced reconfiguration of the dsDNA probes with enzyme-assisted target recycling amplification, we describe the development of a signal-on electrochemical sensing approach for sensitive detection of hereditary tyrosinemia type I gene. The dsDNA probes are self-assembled on the sensing electrode, and the addition of the target DNA reconfigures and switches the dsDNA probes into active substrates for exonuclease III, which catalytically digests the probes and leads to cyclic reuse of the target DNA. The target DNA recycling and the removal of one of the ssDNA from the dsDNA probes by exonuclease III result in the formation of many hairpin structures on the sensor surface, which brings the electroactive methylene blue labels into proximity with the electrode and produces a significantly amplified current response for sensitive detection of the target gene down to 0.24 pM. This method is also selective to discriminate single-base mismatch and can be employed to detect the target gene in human serum samples. With the demonstration for the detection of the target gene, we expect the developed method to be a universal sensitive sensing platform for the detection of different nucleic acid sequences.

Multiplexed and amplified electronic sensor for the detection of microRNAs from cancer cells.

The detection of microRNA expression profiles plays an important role in early diagnosis of different cancers. On the basis of the employment of redox labels with distinct potential positions and duplex specific nuclease (DSN)-assisted target recycling signal amplifications, we have developed a multiplexed and convenient electronic sensor for highly sensitive detection of microRNA (miRNA)-141 and miRNA-21. The sensor is constructed by self-assembly of thiol-modified, redox species-labeled hairpin probes on the gold sensing electrode. The hybridizations between the target miRNAs and the surface-immobilized probes lead to the formation of RNA/DNA duplexes, and DSN subsequently cleaves the redox-labeled hairpin probes of the RNA/DNA duplexes to recycle the target miRNAs and to generate significantly amplified current suppression at different potentials for multiplexed detection of miRNA-141 and miRNA-21 down to 4.2 and 3.0 fM, respectively. The sensor is also highly selective toward the target miRNAs and can be employed to monitor miRNAs from human prostate carcinoma (22Rv1) and breast cancer (MCF-7) cell lysates simultaneously. The sensor reported here thus holds great potential for the development of multiplexed, sensitive, selective, and simple sensing platforms for simultaneous detection of a variety of miRNA biomarkers for clinic applications with careful selection of the labels.

Tissue ultrasound imaging based on wavelet correlation analysis and pulse-inversion technique.

BACKGROUND: Pulse-inversion-based tissue harmonic imaging has been utilized for many years because it can effectively eliminate the harmonic leakage and produce low side-lobe. However, the pulse inversion method is sensitive to imaging object movements, which may result in motion artifacts. Spatial resolution and contrast were limited. OBJECTIVE: To improve ultrasound image quality by a new pulse-inversion-based tissue harmonic imaging technique. METHODS: Continuous wavelet transform is applied to investigate the correlation between mother wavelet and the received echoes from two opposite pulses. To get a better correlation, a novel mother wavelet named 'tissue wavelet' is designed based on the Khokhlov-Zabolotskaya- Kuznetsov (KZK) wave equation. Radio frequency data were obtained from open Ultrasonix SonixTouch imaging system. Experiments were carried on ultrasonic tissue phantom, human carotid artery and human liver. RESULTS: The average improvement of lateral spatial resolution is 49.52% compared to pulse-inversion-based tissue second-harmonic Imaging (PIHI). Contrast ratio (CR) and contrast-to-noise ratio (CNR) increased by 5.55 dB and 1.40 dB over PIHI. Tissue wavelet performs better than Mexh and Morl wavelet in lateral spatial resolution, CR, and CNR. CONCLUSION: The proposed technique effectively improves the imaging quality in lateral spatial resolution, CR, and CNR.

Defective state regulation of Ru-doped Nb2O5 boosts fast lithium storage.

Breaking through the limitations of lithium-ion transmission is imperative for high-power rechargeable batteries. As a promising anode material for fast-charging lithium-ion batteries (LIBs), niobium pentoxide (Nb2O5) has garnered considerable research attention due to its exceptional rate performance, stable lithium storage performance and high safety attributes. Nevertheless, the limited intrinsic conductivity of Nb2O5, coupled with its structural degradation during the cycling process, imposes constraints on its viability as a commercially viable electrode material. Herein, a ruthenium (Ru) doping method is employed to regulate the oxygen defects and the interlayer spacing of the tetragonal Nb2O5 (M-Nb2O5), offering superior reaction kinetics, higher stability for lithium storage sites and more unobstructed lithium-ion transport channels. Ru-doped Nb2O5 (RNO) manifests excellent electrochemical properties, including remarkable rate capacity (166 mAh/g at 80C), reversible capacity (246.98 mAh/g at 0.5C), improved initial Coulombic efficiency (95.77 % compared to 81.44 % of the pure sample) and cycling stability (maintaining a capacity of 113.5 mAh/g at 10C for 2,000 cycles). The enhancement mechanism of Ru doping on the structural stability and ion transport kinetics in tetragonal Nb2O5 is comprehensively elucidated through diverse electrochemical analyses and in-situ techniques.

Plane-wave medical image reconstruction based on dynamic Criss-Cross attention and multi-scale convolution.

BACKGROUND: Plane-wave imaging is widely employed in medical imaging due to its ultra-fast imaging speed. However, the image quality is compromised. Existing techniques to enhance image quality tend to sacrifice the imaging frame rate. OBJECTIVE: The study aims to reconstruct high-quality plane-wave images while maintaining the imaging frame rate. METHODS: The proposed method utilizes a U-Net-based generator incorporating a multi-scale convolution module in the encoder to extract information at different levels. Additionally, a Dynamic Criss-Cross Attention (DCCA) mechanism is proposed in the decoder of the U-Net-based generator to extract both local and global features of plane-wave images while avoiding interference caused by irrelevant regions. RESULTS: In the reconstruction of point targets, the experimental images achieved a reduction in Full Width at Half Maximum (FWHM) of 0.0499 mm, compared to the Coherent Plane-Wave Compounding (CPWC) method using 75-beam plane waves. For the reconstruction of cyst targets, the simulated image achieved a 3.78% improvement in Contrast Ratio (CR) compared to CPWC. CONCLUSIONS: The proposed model effectively addresses the issue of unclear lesion sites in plane-wave images.

Intensive chemotherapy with dual induction and ALL-like consolidation for childhood acute myeloid leukemia: a respective report from multiple centers in China.

Background: Pediatric acute myeloid leukemia (AML) has poor prognosis and high rate of relapse and mortality, and exploration of new treatment options is still critically needed. Objectives: To summarize the outcome of our new treatment strategies for pediatric AML, which is characterized by dual induction and acute lymphoblastic leukemia (ALL) elements consolidation. Design: Retrospective, single-arm study. Methods: From July 2012 to December 2019, an intensive chemotherapy protocol was used for newly diagnosed children with AML, which contains dual induction, three courses of consolidations based on high-dose cytarabine, and two courses of consolidations composed of high-dose methotrexate, vincristine, asparaginase, and mercaptopurine (ALL-like elements). Blasts were monitored by bone marrow smears at intervals, and two lumbar punctures were performed during chemotherapy. We retrospectively analyzed the efficacy and safety of this study. The last follow-up was on 26 May 2023. Results: A total of 70 pediatric AMLs were included. The median age at diagnosis was 6.7 (0.5-16.0) years. The median initial WBC count was 23.74 × 109/L, 11 of whom ⩾100 × 109/L. After dual induction, there were 62 cases of complete remission (CR), 5 cases of partial remission, and 3 cases of nonremission. The CR rate was 88.57%. The median follow-up time was 5.8 (0.2-9.4) years, the 5-year overall survival was 78.2% ± 5%, the event-free survival (EFS) was 71.2% ± 5.6%, and the cumulative recurrence rate was 27.75%. The 5-year EFS of patients with initial WBC < 100 × 109/L (n = 59) and ⩾100 × 109/L (n = 11) were 76.4% ± 5.7% and 45.5% ± 15% (p = 0.013), respectively. A total of 650 hospital infections occurred. The main causes of infection were respiratory tract infection (26.92%), septicemia (18.46%), stomatitis (11.85%), and skin and soft-tissue infection (10.46%). Conclusion: This intensive treatment protocol with dual induction and ALL-like elements is effective and safe for childhood AML. Initial WBC ⩾ 100 × 109/L was the only independent risk factor in this cohort. Trial registration: It is a retrospective study, and no registration on ClinicalTrials.gov.

HIV-1 Molecular Networks and Pretreatment Drug Resistance at the Frontier of Yunnan Province, China.

The border areas of Yunnan Province in China are severely affected by human immunodeficiency virus (HIV). To investigate the risk of HIV transmission and assess the prevalence of pretreatment drug resistance (PDR) in the border area, blood samples were collected from individuals with newly reported HIV in 2021 in three border counties (Cangyuan, Gengma, and Zhenkang) in Yunnan Province. Among the 174 samples successfully genotyped, eight circulating recombinant forms (CRFs), two subtypes, and several unique recombinant forms (URFs) were identified. CRF08_BC (56.9%, 99/174), URFs (14.4%, 25/174), CRF01_AE (10.9%, 19/174), and CRF07_BC (8.0%, 14/174) were the main genotypes. CRF08_BC and URFs were detected more frequently in Chinese and Burmese individuals, respectively. CRF07_BC was found more frequently in men who have sex with men. The proportion of individuals detected in HIV-1 networks was only associated with case-reporting counties. When stratified by county, individuals aged ≤40 years in Cangyuan and ≥41 years in Gengma were more likely to be found in these networks. Furthermore, 93.8% (15/16) of the links in Cangyuan and 79.4% (50/63) of those in Gengma were located within their own counties. The prevalence of PDR to any antiretroviral drug, nucleoside reverse transcriptase inhibitors (NRTIs), and non-nucleoside reverse transcriptase inhibitors (NNRTIs) were 10% (17/170), 0.6% (1/170), and 9.4% (16/170), respectively. The most frequent resistance-associated mutations (RAMs) were V179D/VD/E/T (22.9%, 39/170) and E138A/G/K/R (13.5%, 23/170). In the molecular networks, six clusters shared common RAMs. HIV-1 genetics has become more diverse in border areas. HIV-1 molecular network analysis revealed the different characteristics of the HIV-1 epidemic in the border counties. The prevalence of PDR showed an upward trend, and the PDR to NNRTIs was close to the public response threshold. These findings provide information for the development of AIDS prevention and treatment strategies.

Effectiveness of Frequent Viral Load Testing Plus Additional Interventions to Prevent HIV Transmission in Heterosexual, Serodiscordant Couples - Yunnan Province, China, 2019-2021.

What is already known about this topic?: HIV transmission among serodiscordant couples remains a persistent issue in China. However, the practice of combining counseling with antiretroviral therapies (ART) to enhance ART adherence is not widely implemented or recommended in Chinese health guidelines. What is added by this report?: This randomized controlled trial suggests that increased follow-up, counseling, and awareness of HIV risk can enhance ART compliance, thereby maximizing treatment efficacy. What are the implications for public health practice?: Early testing and counseling of serodiscordant couples, following the identification of a human immunodeficiency virus (HIV) positive spouse, is crucial for initiating ART and reducing the risk of seroconversion in the uninfected partner. Implementing a combination of ART and adjunct counseling in China is advisable.

Revealing the Bacterial Quorum-Sensing Effect on the Biofilm Formation of Diatom Cylindrotheca sp. Using Multimodal Imaging.

Diatoms contribute to carbon fixation in the oceans by photosynthesis and always form biofouling organized by extracellular polymeric substances (EPS) in the marine environment. Bacteria-produced quorum-sensing signal molecules N-acyl homoserine lactones (AHLs) were found to play an important role in the development of Cylindrotheca sp. in previous studies, but the EPS composition change was unclear. This study used the technology of alcian blue staining and scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), and time-of-flight secondary ion mass spectrometry (ToF-SIMS) to directly observe the biofilm formation process. The results showed that AHLs promote the growth rates of diatoms and the EPS secretion of biofilm components. AHLs facilitated the diatom-biofilm formation by a forming process dependent on the length of carbon chains. AHLs increased the biofilm thickness and the fluorescence intensity and then altered the three-dimensional (3D) structures of the diatom-biofilm. In addition, the enhanced EPS content in the diatom-biofilm testified that AHLs aided biofilm formation. This study provides a collection of new experimental evidence of the interaction between bacteria and microalgae in fouling biofilms.

Molecular detection of per- and polyfluoroalkyl substances in water using time-of-flight secondary ion mass spectrometry.

Detection of per- and polyfluoroalkyl substances (PFASs) is crucial in environmental mitigation and remediation of these persistent pollutants. We demonstrate that time-of-flight secondary ion mass spectrometry (ToF-SIMS) is a viable technique to analyze and identify these substances at parts per trillion (ppt) level in real field samples without complicated sample preparation due to its superior surface sensitivity. Several representative PFAS compounds, such as perfluorooctanesulfonic acid (PFOS), perfluorobutanoic acid (PFBA), perfluoropentanoic acid (PFPeA), perfluoheptanoic acid (PFHpA), and perfluorononanoic acid (PFNA), and real-world groundwater samples collected from monitoring wells installed around at a municipal wastewater treatment plant located in Southern California were analyzed in this work. ToF-SIMS spectral comparison depicts sensitive identification of pseudo-molecular ions, characteristic of reference PFASs. Additionally, principal component analysis (PCA) shows clear discrimination among real samples and reference compounds. Our results show that characteristic molecular ion and fragments peaks can be used to identify PFASs. Furthermore, SIMS two-dimensional (2D) images directly exhibit the distribution of perfluorocarboxylic acid (PFCA) and PFOS in simulated mixtures and real wastewater samples. Such findings indicate that ToF-SIMS is useable to determine PFAS compounds in complex environmental water samples. In conclusion, ToF-SIMS provides simple sample preparation and high sensitivity in mass spectral imaging, offering an alternative solution for environmental forensic analysis of PFASs in wastewater in the future.

One-step detection of Bean pod mottle virus in soybean seeds by the reverse-transcription loop-mediated isothermal amplification.

BACKGROUND: Bean pod mottle virus (BPMV) is a wide-spread and destructive virus that causes huge economic losses in many countries every year. A sensitive, reliable and specific method for rapid surveillance is urgently needed to prevent further spread of BPMV. METHODS: A degenerate reverse-transcription loop-mediated isothermal amplification (RT-LAMP) primer set was designed on the conserved region of BPMV CP gene. The reaction conditions of RT-LAMP were optimized and the feasibility, specificity and sensitivity of this method to detect BPMV were evaluated using the crude RNA rapidly extracted from soybean seeds. RESULTS: The optimized RT-LAMP parameters including 6 mM MgCl2, 0.8 M betaine and temperature at 62.5-65°C could successfully amplify the ladder-like bands from BPMV infected soybean seeds. The amplification was very specific to BPMV that no cross-reaction was observed with other soybean viruses. Inclusion of a fluorescent dye makes it easily be detected in-tube by naked eye. The sensitivity of RT-LAMP assay is higher than the conventional RT-PCR under the conditions tested, and the conventional RT-PCR couldn't be used for detection of BPMV using crude RNA extract from soybean seeds. CONCLUSION: A highly efficient and practical method was developed for the detection of BPMV in soybean seeds by the combination of rapid RNA extraction and RT-LAMP. This RT-LAMP method has great potential for rapid BPMV surveillance and will assist in preventing further spread of this devastating virus.