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"Chen, Hongjun"
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A genome-wide CRISPR screen identifies host factors that regulate SARS-CoV-2 entry
The global spread of SARS-CoV-2 is posing major public health challenges. One feature of SARS-CoV-2 spike protein is the insertion of multi-basic residues at the S1/S2 subunit cleavage site. Here, we find that the virus with intact spike (Sfull) preferentially enters cells via fusion at the plasma membrane, whereas a clone (Sdel) with deletion disrupting the multi-basic S1/S2 site utilizes an endosomal entry pathway. Using Sdel as model, we perform a genome-wide CRISPR screen and identify several endosomal entry-specific regulators. Experimental validation of hits from the CRISPR screen shows that host factors regulating the surface expression of angiotensin-converting enzyme 2 (ACE2) affect entry of Sfull virus. Animal-to-animal transmission with the Sdel virus is reduced compared to Sfull in the hamster model. These findings highlight the critical role of the S1/S2 boundary of SARS-CoV-2 spike protein in modulating virus entry and transmission and provide insights into entry of coronaviruses.
The SARS-CoV-2 spike protein contains a multi-basic cleavage site. Here, the authors show how this multi-basic cleavage site affects entry of SARS-CoV-2 into cells and transmission in the hamster model and identify host factors affecting entry of SARS-CoV-2 in a genome-wide CRISPR screen.
Journal Article
Switched photocurrent direction in Au/TiO2 bilayer thin films
2015
Switched photocurrent direction in photoelectrodes is a very interesting phenomenon and has demonstrated their potentials in important applications including photodiodes, phototransistors, light-driven sensors and biosensors. However, the design and mechanism understanding of such photoelectrodes remain challenging to date. Here we report a new phenomenon of sequence-driven the photocurrent direction on a simple bilayer structure of 5 nm thick Au and 10 nm TiO
2
under visible-light irradiation. It is found that when Au layer are deposited as the outer layer on TiO
2
coated fluorine doped tin oxide (FTO) substrate (designated as FTO/TiO
2
/Au), anodic photocurrent is obtained due to the band bending formed at the electrode-electrolyte interface. Interestingly, simply swapping the deposition sequence of Au and TiO
2
leads to cathodic photocurrent on FTO/Au/TiO
2
electrode. Characterization and calculations on the photoelectrode reveals that the photogenerated electrons can be easily trapped in the energy well formed between the band bending and the Schottky contact, which allows electronic tunnelling through the 1.6 nm thick space charge layer, resulting in a unique anodic to cathodic photocurrent conversion. The understanding of this new phenomenon can be important for designing new generation optoelectronic converting devices in a low-cost and facile manner.
Journal Article
Food safety governance in China: From supervision to coregulation
by
Liu, Zhe
,
Chen, Hongjun
,
Mutukumira, Anthony N.
in
Abuse
,
Agricultural production
,
Consumer protection
2019
The food control and regulatory system in China is beset by several challenges. While firms have to reduce their costs in pursuit of benefits, customers are increasingly focusing on safety and quality of food products. Although the Chinese government has developed more stringent regulatory measures, food safety incidents still occur, including abuse of food additives, adulterated products as well as contamination by pathogenic microorganisms, pesticides, veterinary drug residues, and heavy metals, and use of substandard materials. A national food safety strategy has been proposed to assure food safety from “farm to table.” This paper begins with the analysis of current food regulatory systems and then discusses cogovernance of food safety management in China. We explore the practice in the city of Shenzhen where government intervention has strengthened food control, thereby creating an opportunity to form a coregulatory system. The review highlights that the current food safety regulatory system of multi‐agency structure can inevitably lead to insufficient incentives for business entities. Due to asymmetric information, lack of regulatory resources, and consumer advocacy, coregulation has been developed and is increasingly being promoted as an important instrument of food regulation. In this manuscript, we divide the development of Chinese food safety regulation into five stages, including centralized management (1949–1979), multisector management (1979–1995), matrix management (1995–2009), process management (2009–2015), and integrated management (2015 to date), and show that there are still many challenges from stakeholders, technology, and resources. Due to asymmetric information, lack of regulatory resources, and consumer advocacy, coregulation has been developed and is increasingly being promoted as an important instrument of regulation. The paper presents a conceptual framework of enforcement of food safety regulation for use in shifting toward coregulation from traditional approaches, based on the case study of Shenzhen.
Journal Article
The effect of physical interventions on pain control after orthodontic treatment: A systematic review and network meta-analysis
2024
Pain is a frequent adverse reaction during orthodontic treatment, which can significantly reduce treatment compliance and compromise the expected treatment effect. Physical interventions have been used to alleviate pain after orthodontic treatment, but their effectiveness is controversial. This study used a network meta-analysis to assess the efficacy of various physical interventions typically used in managing pain after orthodontic treatment, with a view to provide evidence-based recommendations for representative interventions for orthodontic pain relief during peak pain intensity.
A systematic search of six electronic databases, from their respective inception dates, was conducted to identify relevant literature on the efficacy of various typical physical interventions for managing pain after orthodontic treatment. Literature screening was performed according to the Cochrane System Evaluator's Manual. Stata 16.0 was used to assess heterogeneity, inconsistency, publication bias, and sensitivity to generate an evidence network diagram and conduct a network meta-analysis.
In total, 771 articles were reviewed to collect literature on interventions, including low-level laser therapy (LLLT), vibration, acupuncture, and chewing. Of these, 28 studies using a visual analog scale (VAS) as an outcome indicator were included. The results showed that LLLT, vibration, acupuncture, and chewing effectively relieved the pain symptoms in patients after orthodontic treatment. At 24 h post-treatment, LLLT (surface under the cumulative ranking curve [SUCRA] = 80.8) and vibration (SUCRA = 71.1) were the most effective interventions. After 48 h of treatment, acupuncture (SUCRA = 89.6) showed a definite advantage as the best intervention.
LLLT, vibration, acupuncture, and chewing can alleviate pain associated with orthodontic treatment. Among these interventions, acupuncture was found to be the most effective at 48 h after orthodontic treatment. In addition, acupuncture demonstrated long-lasting and stable pain-relieving effects. However, further studies are needed to determine the most suitable equipment-specific parameters for acupuncture in relieving pain associated with orthodontic treatment.
Journal Article
Herbicidal safening activity of Loropetalum chinense extract in alleviating pretilachlor-induced phytotoxicity in rice
by
Tang, Xing
,
Jin, Chenzhong
,
Chen, Hongjun
in
alleviating phytotoxicity
,
herbicidal safener
,
Loropetalum chinense extract
2026
In this study, the crude extract of natural Loropetalum chinense (LoE) was prepared using a simple ethanol leaching approach. Preliminary evaluations of the safening effect of LoE in both agar and soil media demonstrated its ability to protect rice seedlings from damage induced by the herbicide pretilachlor (Pre). Specifically, treatment with LoE at 50 mg/L resulted in a 40.35% increase in root length and a 25.11% increase in plant height. In contrast, treatment at 100 mg/L led to a 36.85% increase in fresh weight, demonstrating effectiveness comparable to that of the commercial safener fenclorim (Fen). Moreover, compared to rice seedlings treated with Pre alone, LoE significantly increased the levels of glutathione (GSH) and enhanced the activities of several important enzymes: glutathione S-transferase (GST), superoxide dismutase (SOD), and catalase (CAT). The mechanism of action for LoE appears to involve enhancing GST activity to accelerate the metabolism of Pre and improving herbicide tolerance by activating antioxidant enzymes. Overall, LoE shows promise as a potential eco-friendly, plant-derived herbicide safener candidate for pretilachlor. For practical commercial application, further efforts should focus on (i) clarifying the phytochemical profile of LoE extracts, and (ii) conducting in-depth assessments of LoE’s mechanisms of action, including studies on degradation kinetics and metabolite formation.
Journal Article
Recent Advances in Dielectric Properties-Based Soil Water Content Measurements
2024
Dielectric properties are crucial in understanding the behavior of water within soil, particularly the soil water content (SWC), as they measure a material’s ability to store an electric charge and are influenced by water and other minerals in the soil. However, a comprehensive review paper is needed that synthesizes the latest developments in this field, identifies the key challenges and limitations, and outlines future research directions. In addition, various factors, such as soil salinity, temperature, texture, probing space, installation gap, density, clay content, sampling volume, and environmental factors, influence the measurement of the dielectric permittivity of the soil. Therefore, this review aims to address the research gap by critically analyzing the current state-of-the-art dielectric properties-based methods for SWC measurements. The motivation for this review is the increasing importance of precise SWC data for various applications such as agriculture, environmental monitoring, and hydrological studies. We examine time domain reflectometry (TDR), frequency domain reflectometry (FDR), ground-penetrating radar (GPR), remote sensing (RS), and capacitance, which are accurate and cost-effective, enabling real-time water resource management and soil health understanding through measuring the travel time of electromagnetic waves in soil and the reflection coefficient of these waves. SWC can be estimated using various approaches, such as TDR, FDR, GPR, and microwave-based techniques. These methods are made possible by increasing the dielectric permittivity and loss factor with SWC. The available dielectric properties are further synthesized on the basis of mathematical models relating apparent permittivity to water content, providing an updated understanding of their development, applications, and monitoring. It also analyzes recent mathematical calibration models, applications, algorithms, challenges, and trends in dielectric permittivity methods for estimating SWC. By consolidating recent advances and highlighting the remaining challenges, this review article aims to guide researchers and practitioners toward more effective strategies for SWC measurements.
Journal Article
Lilium regale Wilson WRKY3 modulates an antimicrobial peptide gene, LrDef1, during response to Fusarium oxysporum
2022
Background
WRKY transcription factors (TFs) play vital roles in plant growth and development, secondary metabolite synthesis, and response to biotic and abiotic stresses. In a previous transcriptome sequencing analysis of
Lilium regale
Wilson, we identified multiple WRKY TFs that respond to exogenous methyl jasmonate treatment and lily Fusarium wilt (
Fusarium oxysporum
).
Results
In the present study, the WRKY TF
LrWRKY3
was further analyzed to reveal its function in defense response to
F. oxysporum
. The LrWRKY3 protein was localized in the plant cell nucleus, and
LrWRKY3
transgenic tobacco lines showed higher resistance to
F. oxysporum
compared with wild-type (WT) tobacco. In addition, some genes related to jasmonic acid (JA) biosynthesis, salicylic acid (SA) signal transduction, and disease resistance had higher transcriptional levels in the
LrWRKY3
transgenic tobacco lines than in the WT. On the contrary,
L. regale
scales transiently expressing
LrWRKY3
RNA interference fragments showed higher sensitivity to
F. oxysporum
infection. Moreover, a
F. oxysporum
-induced defensin gene,
Def1
, was isolated from
L. regale
, and the recombinant protein LrDef1 isolated and purified from
Escherichia coli
possessed antifungal activity to several phytopathogens, including
F. oxysporum
. Furthermore, co-expression of
LrWRKY3
and the
LrDef1
promoter in tobacco enhanced the LrDef1 promoter-driven expression activity.
Conclusions
These results clearly indicate that
LrWRKY3
is an important positive regulator in response to
F. oxysporum
infection, and one of its targets is the antimicrobial peptide gene
LrDef1
.
Journal Article
A Fenclorim Molecularly Imprinted Electrochemical Sensor Based on a Polycatechol/Ti3C2Tx Composite
2025
Given the significance of safeners and their potential to emit harmful substances into the environment, it is essential to develop suitable analytical methods for detecting these compounds. This study presents a molecularly imprinted electrochemical sensor designed for the sensitive and rapid detection of fenclorim (FM), a type of safener. Titanium carbide nanomaterials (Ti3C2Tx) were electrochemically deposited onto the glassy carbon electrode (GCE) to enhance electron transfer. Subsequently, molecularly imprinted polymers were fabricated through the electropolymerization of catechol in the presence of FM. The electrochemical behavior of each modified electrode was investigated using differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Under optimized experimental conditions, the MIP/Ti3C2Tx/GCE sensor demonstrated a linear relationship with FM concentration ranging from 5 to 300 nM, with a limit of detection (LOD) of 1.56 nM (S/N = 3). Additionally, the sensor demonstrated excellent selectivity, stability, and reproducibility for FM detection and was successfully utilized for quantifying FM in real water samples.
Journal Article
Tobacco control law enforcement in Hangzhou, China: a qualitative study
2025
BackgroundThe updated version of the Regulation on Smoking Control in Public Places in Hangzhou commenced on 1 January 2019.ObjectiveThis study aims to summarise Hangzhou’s municipal-level law enforcement experience and to analyse facilitators and impediments to the implementation of the Regulation.DesignQualitative methods are used in this study.SettingThe participants were invited to participate in online interviews.ParticipantsA total of 10 individuals from Hangzhou’s municipal, district and county levels, involved in tobacco control, participated in semistructured interviews employing the grounded theory.ResultsThe primary coding themes of concern to the interviewees were the ‘law enforcement programme’, the ‘law enforcement agencies’ and the ‘law enforcement monitoring’. The secondary coding themes of interest were the ‘role and division of labour’, the ‘inspection procedure’ and the ‘frequency of law enforcement’. The study found that facilitators to the implementation of the tobacco control law in Hangzhou include the incremental enhancement of the coordination mechanism and workflow of joint law enforcement agencies; the balanced administrative enforcement of tobacco control under the guidance of the flexible law enforcement strategy and the institution of law enforcement monitoring based on the Healthy Hangzhou Assessment. Impediments identified include inadequate interfacing and integration of data and platforms related to tobacco control law enforcement; differences in the law enforcement processes among different agencies; understaffing in tobacco control law enforcement agencies represented by non-health departments; and the absence of systematic performance evaluation and incentive mechanisms for routine tobacco control law enforcement.ConclusionFurther improvement in the implementation of the tobacco control law is needed in Hangzhou in the future.
Journal Article
Adaptive Impedance Control of a Human–Robotic System Based on Motion Intention Estimation and Output Constraints
2025
The rehabilitation exoskeleton represents a typical human–robot system featuring complex nonlinear dynamics. This paper is devoted to proposing an adaptive impedance control strategy for a rehabilitation exoskelton. The patient’s motion intention is estimated online by the neural network (NN) to cope with the intervention of the patient’s subjective motor awareness in the late stage of rehabilitation training. Due to the differences in impedance parameters for training tasks in individual patients and periods, the least square method was used to learn the impedance parameters of the patient. Considering the uncertainties of the exoskeleton and the safety of rehabilitation training, an adaptive neural network impedance controller with output constraints was designed. The NN was applied to approximate the unknown dynamics and the barrier Lyapunov function was applied to prevent the system from violating the output rules. The feasibility and effectiveness of the proposed strategy were verified by simulation.
Journal Article