From fears of evaluation to social anxiety: The longitudinal relationships and neural basis in healthy young adults

Background: Social anxiety disorder (SAD) is a common mental health problem, and its core cognitive manifestation is the persistent fear of being evaluated, including both negatively (FNE) and positively (FPE). This study aimed to examine the longitudinal relationships of FNE, FPE and SAD and explore their neural basis. Methods: Three samples were retrieved in this study. First, the data of 649 college students who completed a survey and fMRI scan were used to explore the neural basis of FNE, FPE, and SAD symptoms. Next, the data of 450 participants who completed the same survey twice were used to examine the longitudinal relationships of the variables. Finally, the overlapping of the two samples (N = 288) who completed two surveys and the fMRI scan were used to establish a brain-behavior model. Results: Both FNE and FPE predicted SAD, and SAD also predicted FPE. The neural signals of subregions in prefrontal cortex were correlated with the scores of FNE, FPE and SAD. Abnormal prefrontal signals influenced SAD symptoms via fears of evaluation. Conclusions: Our findings explain the behavioral and neural underpinnings of social anxiety from a fear of evaluation angle. This contributes to a better theorical understanding of SAD and clinical practice. (AU)

Exogenous abscisic acid prolongs the dormancy of recalcitrant seed of Panax notoginseng.

The seeds of Panax notoginseng (Burk.) F. H. Chen are typically characterized by their recalcitrance and after-ripening process and exhibit a high water content at harvest as well as a high susceptibility to dehydration. Storage difficulty and the low germination of recalcitrant seeds of P. notoginseng are known to cause an obstacle to agricultural production. In this study, the ratio of embryo to endosperm (Em/En) in abscisic acid (ABA) treatments (1 mg·l-1 and 10 mg·l-1, LA and HA) was 53.64% and 52.34%, respectively, which were lower than those in control check (CK) (61.98%) at 30 days of the after-ripening process (DAR). A total of 83.67% of seeds germinated in the CK, 49% of seeds germinated in the LA treatment, and 37.33% of seeds germinated in the HA treatment at 60 DAR. The ABA, gibberellin (GA), and auxin (IAA) levels were increased in the HA treatment at 0 DAR, while the jasmonic acid (JA) levels were decreased. ABA, IAA, and JA were increased, but GA was decreased with HA treatment at 30 DAR. A total of 4,742, 16,531, and 890 differentially expressed genes (DEGs) were identified between the HA-treated and CK groups, respectively, along with obvious enrichment in the ABA-regulated plant hormone pathway and the mitogen-activated protein kinase (MAPK) signaling pathway. The expression of pyracbactin resistance-like (PYL) and SNF1-related protein kinase subfamily 2 (SnRK2s) increased in the ABA-treated groups, whereas the expression of type 2C protein phosphatase (PP2C) decreased, both of which are related to the ABA signaling pathway. As a result of the changes in expression of these genes, increased ABA signaling and suppressed GA signaling could inhibit the growth of the embryo and the expansion of developmental space. Furthermore, our results demonstrated that MAPK signaling cascades might be involved in the amplification of hormone signaling. Meanwhile, our study uncovered that the exogenous hormone ABA could inhibit embryonic development, promote dormancy, and delay germination in recalcitrant seeds. These findings reveal the critical role of ABA in regulating the dormancy of recalcitrant seeds, and thereby provide a new insight into recalcitrant seeds in agricultural production and storage.

Genome-wide identification and characterization of members of the LEA gene family in Panax notoginseng and their transcriptional responses to dehydration of recalcitrant seeds.

BACKGROUND: Late embryogenesis abundant (LEA) proteins play an important role in dehydration process of seed maturation. The seeds of Panax notoginseng (Burkill) F. H. Chen are typically characterized with the recalcitrance and are highly sensitive to dehydration. However, it is not very well known about the role of LEA proteins in response to dehydration stress in P. notoginseng seeds. We will perform a genome-wide analysis of the LEA gene family and their transcriptional responses to dehydration stress in recalcitrant P. notoginseng seeds. RESULTS: In this study, 61 LEA genes were identified from the P. notoginseng genome, and they were renamed as PnoLEA. The PnoLEA genes were classified into seven subfamilies based on the phylogenetic relationships, gene structure and conserved domains. The PnoLEA genes family showed relatively few introns and was highly conserved. Unexpectedly, the LEA_6 subfamily was not found, and the LEA_2 subfamily contained 46 (75.4%) members. Within 19 pairs of fragment duplication events, among them 17 pairs were LEA_2 subfamily. In addition, the expression of the PnoLEA genes was obviously induced under dehydration stress, but the germination rate of P. notoginseng seeds decreased as the dehydration time prolonged. CONCLUSIONS: We found that the lack of the LEA_6 subfamily, the expansion of the LEA_2 subfamily and low transcriptional levels of most PnoLEA genes might be implicated in the recalcitrant formation of P. notoginseng seeds. LEA proteins are essential in the response to dehydration stress in recalcitrant seeds, but the protective effect of LEA protein is not efficient. These results could improve our understanding of the function of LEA proteins in the response of dehydration stress and their contributions to the formation of seed recalcitrance.

Gastrodin alleviates rat chondrocyte senescence and mitochondrial dysfunction through Sirt3.

Several researchers have focused on understanding the pathogenesis and treatment strategies for osteoarthritis (OA). Gastrodin (GAS) is a potential anti-inflammatory agent. In this study, we constructed an in vitro OA chondrocyte model by treating chondrocytes with IL-1ß. Next, we determined the expression of aging-related markers and mitochondrial functions in chondrocytes treated with GAS. Further, we constructed a "drug-component-target-pathway-disease" interactive network and determined the effect of GAS on the functions and pathways related to OA. Finally, we constructed the OA rat model by removing the medial meniscus of the right knee and transection of the anterior cruciate ligament. The results revealed that GAS reduced senescence and improved mitochondrial functions in OA chondrocytes. We used network pharmacology and bioinformatics to screen for key molecules Sirt3 and the PI3K-AKT pathway involved in regulating the effect of GAS on OA. Further studies showed an increase in SIRT3 expression and reduced chondrocyte aging, mitochondrial damage, and the phosphorylation of the PI3K-AKT pathway. The results showed that GAS ameliorates pathological changes related to aging, increases SIRT3 expression, and protects the ECM in the OA rat model. These results were consistent with our bioinformatics results and previous studies. In summary, GAS slows down the aging of chondrocytes and mitochondrial damage in OA by regulating the phosphorylation of the PI3K-AKT pathway via SIRT3.

High nitrogen inhibits biomass and saponins accumulation in a medicinal plant Panax notoginseng.

Nitrogen (N) is an important macronutrient and is comprehensively involved in the synthesis of secondary metabolites. However, the interaction between N supply and crop yield and the accumulation of effective constituents in an N-sensitive medicinal plant Panax notoginseng (Burkill) F. H. Chen is not completely known. Morphological traits, N use and allocation, photosynthetic capacity and saponins accumulation were evaluated in two- and three-year-old P. notoginseng grown under different N regimes. The number and length of fibrous root, total root length and root volume were reduced with the increase of N supply. The accumulation of leaf and stem biomass (above-ground) were enhanced with increasing N supply, and LN-grown plants had the lowest root biomass. Above-ground biomass was closely correlated with N content, and the relationship between root biomass and N content was negatives in P. notoginseng (r = -0.92). N use efficiency-related parameters, NUE (N use efficiency, etc.), NC (N content in carboxylation system component) and P n (the net photosynthetic rate) were reduced in HN-grown P. notoginseng. SLN (specific leaf N), Chl (chlorophyll), NL (N content in light capture component) increased with an increase in N application. Interestingly, root biomass was positively correlated with NUE, yield and P n. Above-ground biomass was close negatively correlated with photosynthetic N use efficiency (PNUE). Saponins content was positively correlated with NUE and P n. Additionally, HN improved the root yield of per plant compared with LN, but reduced the accumulation of saponins, and the lowest yield of saponins per unit area (35.71 kg·hm-2) was recorded in HN-grown plants. HN-grown medicinal plants could inhibit the accumulation of root biomass by reducing N use and photosynthetic capacity, and HN-induced decrease in the accumulation of saponins (C-containing metabolites) might be closely related to the decline in N efficiency and photosynthetic capacity. Overall, N excess reduces the yield of root and C-containing secondary metabolites (active ingredient) in N-sensitive medicinal species such as P. notoginseng.

Exogenous gibberellic acid shortening after-ripening process and promoting seed germination in a medicinal plant Panax notoginseng.

BACKGROUND: Panax notoginseng (Burk) F.H. Chen is an essential plant in the family of Araliaceae. Its seeds are classified as a type of morphophysiological dormancy (MPD), and are characterized by recalcitrance during the after-ripening process. However, it is not clear about the molecular mechanism on the after-ripening in recalcitrant seeds. RESULTS: In this study, exogenous supply of gibberellic acid (GA3) with different concentrations shortened after-ripening process and promoted the germination of P. notoginseng seeds. Among the identified plant hormone metabolites, exogenous GA3 results in an increased level of endogenous hormone GA3 through permeation. A total of 2971 and 9827 differentially expressed genes (DEGs) were identified in response to 50 mg L-1 GA3 (LG) and 500 mg L-1 GA3 (HG) treatment, respectively, and the plant hormone signal and related metabolic pathways regulated by GA3 was significantly enriched. Weighted gene co-expression network analysis (WGCNA) revealed that GA3 treatment enhances GA biosynthesis and accumulation, while inhibiting the gene expression related to ABA signal transduction. This effect was associated with higher expression of crucial seed embryo development and cell wall loosening genes, Leafy Contyledon1 (LEC1), Late Embryogenesis Abundant (LEA), expansins (EXP) and Pectinesterase (PME). CONCLUSIONS: Exogenous GA3 application promotes germination and shorts the after-ripening process of P. notoginseng seeds by increasing GA3 contents through permeation. Furthermore, the altered ratio of GA and ABA contributes to the development of the embryo, breaks the mechanical constraints of the seed coat and promotes the protrusion of the radicle in recalcitrant P. notoginseng seeds. These findings improve our knowledge of the contribution of GA to regulating the dormancy of MPD seeds during the after-ripening process, and provide new theoretical guidance for the application of recalcitrant seeds in agricultural production and storage.

Dam construction alters planktonic microbial predator‒prey communities in the urban reaches of the Yangtze River.

While dam construction supports social and economic development, changes in hydraulic conditions can also affect natural aquatic ecosystems, especially microbial ecosystems. The compositional and functional traits of multi-trophic microbiota can be altered by dam construction, which may result in changes in aquatic predator-prey interactions. To understand this process, we performed a large-scale sampling campaign in the urban reaches of the dam-impacted Yangtze River (1 995 km) and obtained 211 metagenomic datasets and water quality data. We first compared the compositional traits of planktonic microbial communities upstream, downstream, and in a dam reservoir. Results showed that Bacteroidetes (R-strategy) bacteria were more likely to survive upstream, whilst the reservoir and downstream regions were more conducive to the survival of K-strategy bacteria such as Actinobacteria. Eukaryotic predators tended to be enriched upstream, whilst phototrophs tended to be enriched in the reservoir and downstream regions. Based on bipartite networks, we inferred that the potential microbial predator-prey interactions gradually and significantly decreased from upstream to the downstream and dam regions, affecting 56% of keystone microbial species. Remarkably, functional analysis showed that the abundance of the photosynthetic gene psbO was higher in the reservoir and downstream regions, whilst the abundance of the KEGG carbohydrate metabolic pathway was higher upstream. These results indicate that dam construction in the Yangtze River induced planktonic microbial ecosystem transformation from detritus-based food webs to autotroph-based food webs.

An instant beverage rich in nutrients and secondary metabolites manufactured from stems and leaves of Panax notoginseng.

Introduction: Radix Notoginseng, one of the most famous Chinese traditional medicines, is the dried root of Panax notoginseng (Araliaceae). Stems and leaves of P. notoginseng (SLPN) are rich in secondary metabolites and nutrients, and authorized as a food resource, however, its utilization needs further research. Methods: A SLPN-instant beverage was manufactured from SLPN through optimization by response surface design with 21-fold of 48.50% ethanol for 39 h, and this extraction was repeated twice; the extraction solution was concentrated to 1/3 volume using a vacuum rotatory evaporator at 45°C, and then spray dried at 110°C. Nutritional components including 14 amino acids, ten mineral elements, 15 vitamins were detected in the SLPN-instant beverage; forty-three triterpenoid saponins, e.g., ginsenoside La, ginsenoside Rb3, notoginsenoside R1, and two flavonoid glycosides, as well as dencichine were identified by UPLC-MS. Results: The extraction rate of SLPN-instant beverage was 37.89 ± 0.02%. The majority nutrients were Gly (2.10 ± 0.63 mg/g), His (1.23 ± 0.07 mg/g), α-VE (18.89 ± 1.87 µg/g), ß-VE (17.53 ± 1.98 µg/g), potassium (49.26 ± 2.70 mg/g), calcium (6.73 ± 0.27 mg/g). The total saponin of the SLPN-instant beverage was 403.05 ± 34.98 mg/g, majority was notoginsenoside Fd and with contents of 227 ± 2.02 mg/g. In addition, catechin and γ-aminobutyric acid were detected with levels of 24.57 ± 0.21 mg/g and 7.50 ± 1.85 mg/g, respectively. The SLPN-instant beverage showed good antioxidant activities with half maximal inhibitory concentration (IC50) for scavenging hydroxyl (OH-) radicals, superoxide anion (O2-) radicals, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS+) radicals were 0.1954, 0.2314, 0.4083, and 0.3874 mg/mL, respectively. Conclusion: We optimized an analytical method for in depth analysis of the newly authorized food resource SLPN. Together, an instant beverage with antioxidant activity, rich in nutrients and secondary metabolites, was manufactured from SLPN, which may improve the utilization of SLPN.

A bibliometric analysis of the recent advances in diazepam from 2012 to 2021.

Background: Diazepam is a classic benzodiazepine drug that has been widely used for disorders such as anxiety, sleep disorders, and epilepsy, over the past 59 years. The study of diazepam has always been an important research topic. However, there are few bibliometric analyses or systematic studies in this field. This study undertook bibliometric and visual analysis to ascertain the current status of diazepam research, and to identify research hotspots and trends in the past 10 years, to better understand future developments in basic and clinical research. Methods: Articles and reviews of diazepam were retrieved from the Web of Science core collection. Using CiteSpace, VOSviewer, and Scimago Graphica software, countries, institutions, authors, journals, references, and keywords in the field were visually analyzed. Results: A total of 3,870 publications were included. Diazepam-related literature had high volumes of publications and citations. The majority of publications were from the USA and China. The highest number of publications and co-citations, among the authors, was by James M Cook. Epilepsia and the Latin American Journal of Pharmacy were the journals with the most publications on diazepam and Epilepsia was the most frequently cited journal. Through a comprehensive analysis of keywords and references, we found that current research on diazepam has focused on its mechanism of action, application in disease, pharmacokinetics, risk, assessment, and management of use, status epilepticus, gamma-aminobutyric acid receptors (GABAR), intranasal formulation, gephyrin, and that ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) is the current research hotspot. Conclusion: Research on diazepam is flourishing. We identified research hotspots and trends in diazepam research using bibliometric and visual analytic methods. The clinical applications, mechanisms of action, pharmacokinetics, and assessment and management of the use of diazepam are the focus of current research and the development trend of future research.

A predictable prospect of the South Asian summer monsoon.

Prediction of the South Asian summer monsoon (SASM) has remained a challenge for both scientific research and operational climate prediction for decades. By identifying two dominant modes of the SASM, here we show that the unsatisfactory prediction may be due to the fact that the existing SASM indices are mostly related to the less predictable second mode. The first mode, in fact, is highly predictable. It is physically linked to the variation of the Indian monsoon trough coupled with large rainfall anomalies over core monsoon zone and the northern Bay of Bengal. An index is constructed as a physical proxy of this first mode, which can be well predicted one season in advance, with an overall skill of 0.698 for 1979-2020. This result suggests a predictable prospect of the SASM, and we recommend the new index for real-time monitoring and prediction of the SASM.

Procyanidin B2 ameliorates the progression of osteoarthritis: An in vitro and in vivo study.

OBJECTIVE: Osteoarthritis (OA) is characterized by cartilage degeneration and inflammation. Procyanidin B2 (PCB2), a natural flavonoid compound, exhibits potential anti-inflammatory and anti-oxidative effects against several diseases. However, its curative effects on OA remain unclear. PURPOSE: Herein, we explored the anti-arthritic effects of PCB2 on OA onset and progress and its potential mechanism. METHODS: CCK-8 assays and EdU staining were used to assess the cytotoxic effects and cell proliferation activity of PCB2. Flow cytometry was used to detect apoptosis in chondrocytes. ELISA, qPCR, and western blotting, were applied to explore the expression of apoptosis and senescence-associated secretion phenotype (SASP) factors. The Nrf2/NF-κB signaling cascade was explored using immunofluorescence and western blotting. Additionally, we silenced the Nrf2 gene using siRNAs to verify its function in PCB2 regulation of senescence and apoptosis phenotypes. Safranin O-Fast Green (SO) and immunohistochemical staining were used to explore the effects of PCB2 on OA model rats. RESULTS: PCB2 dampened interleukin (IL)-1ß-triggered expression of SASP factors in vitro. Additionally, PCB2 diminished IL-1ß-triggered destruction of the extracellular matrix (ECM) via downregulating the expression of MMPs, while upregulating the expression of collagen II and aggrecan. In addition, PCB2 treatment reduced IL-1ß-induced apoptosis of chondrocytes. Mechanistically, PCB2 could attenuated chondrocyte senescence in vitro via the Nrf2/NF-κB pathway. Moreover, PCB2 exhibited anti-apoptotic properties via the Nrf2/BAX/Bcl-2 pathway. PCB2 alleviated knee cartilage degeneration in an OA rat model. CONCLUSIONS: Our results suggest that PCB2 may be used as a therapeutic agent for OA.

20S-ginsenoside Rg3 inhibits the biofilm formation and haemolytic activity of Staphylococcus aureus by inhibiting the SaeR/SaeS two-component system.

Introduction. Staphylococcus aureus is a major cause of chronic diseases and biofilm formation is a contributing factor. 20S-ginsenoside Rg3 (Rg3) is a natural product extracted from the traditional Chinese medicine red ginseng.Gap statement. The effects of Rg3 on biofilm formation and haemolytic activity as well as its antibacterial mechanism against S. aureus have not been reported.Aim. This study aimed to investigate the effects of Rg3 on biofilm formation and haemolytic activity as well as its antibacterial action against clinical S. aureus isolates.Methodology. The effect of Rg3 on biofilm formation of clinical S. aureus isolates was studied by crystal violet staining. Haemolytic activity analysis was carried out. Furthermore, the influence of Rg3 on the proteome profile of S. aureus was studied by quantitative proteomics to clarify the mechanism underlying its antibacterial action and further verified by reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR).Results. Rg3 significantly inhibited biofilm formation and haemolytic activity in clinical S. aureus isolates. A total of 63 with >1.5-fold changes in expression were identified, including 34 upregulated proteins and 29 downregulated proteins. Based on bioinformatics analysis, the expression of several virulence factors and biofilm-related proteins, containing CopZ, CspA, SasG, SaeR/SaeS two-component system and SaeR/SaeS-regulated proteins, including leukocidin-like protein 2, immunoglobulin-binding protein G (Sbi) and fibrinogen-binding protein, in the S. aureus of the Rg3-treated group was downregulated. RT-qPCR confirmed that Rg3 inhibited the regulation of SaeR/SaeS and decreased the transcriptional levels of the biofilm-related genes CopZ, CspA and SasG.Conclusions. Rg3 reduces the formation of biofilm by reducing cell adhesion and aggregation. Further, Rg3 can inhibit the SaeR/SaeS two-component system, which acts as a crucial signal transduction system for the anti-virulence activity of Rg3 against clinical S. aureus isolates.

Dissecting the effect of sphingolipid metabolism gene in progression and microenvironment of osteosarcoma to develop a prognostic signature.

Sphingolipid metabolism (SM) fuels tumorigenesis and the malignant progression of osteosarcoma (OS), which leads to an unfavorable prognosis. Elucidating the molecular mechanisms underlying SM in osteosarcoma and developing a SM-based prognostic signature could be beneficial in the clinical setting. This study included 88 frozen OS samples to recognize the vital SM-relevant genes in the development of OS utilizing univariate Cox regression. The Least Absolute Shrinkage and Selection Operator (LASSO) regression analysis was conducted on the SM- relevant genes to minimize the risk of overfitting. The prognostic signature was generate utilizing the multivariable Cox regression analysis and was verified in the validation cohort. Moreover, cellular and molecular mechanisms associated with SM have an unfavorable prognosis for OS patients and have been widely studied. Resultantly, an SM-based prognostic risk model was established according to critical prognostic genes (CBS, GLB1, and HACD1), which had an excellent ability to predict the prognosis of OS patients (AUC for the train cohort was 0.887 and AUC for validation cohort was 0.737). The high-risk OS patients identified based on this prognostic signature had significantly poor immune microenvironment, indicated by significantly low immune score (mean=216.290 ± 662.463), reduced infiltrations of 25 immune cells, including NK cells (LogFC= -0.3597), CD8+T cells ((LogFC=-0.2346), Cytolytic activity ((LogFC=-0.1998), etc. The immunosuppressive microenvironment could be due to dysregulated SM of glycolipids. Further, a nomogram was constructed by integrating the SM-based prognostic signature and clinical paraments to facilitate clinical application. The nomogram could accurately predict the prognosis of OS invalids. Collectively, this study clarified the function of SM in the development of OS and helped develop a tool for risk stratification based on SM-related genes with application in clinical settings. The results of our study will aid in identifying high-risk patients and provide individualized treatments.

Template-Guided Regioselective Encaging of Platinum Single Atoms into Y Zeolite: Enhanced Selectivity in Semihydrogenation and Resistance to Poisoning.

It is challenging to establish single metal atoms with a uniform coordination environment at targeted sites of a zeolite. In this study, single platinum atoms were selectively encaged in the six-membered rings of sodalite (SOD) cages within Y zeolite using a template-guiding strategy. During the in situ synthesis process, template molecules were designed to occupy supercages and thereby force coordinated platinum species into SOD cages. Subsequent control of the post-treatment conditions yielded the Y zeolite with selectively encaged single platinum atoms, denoted Pt@Y-SOD. The Pt@Y-SOD catalyst had good stability and excellent catalytic selectivity in the semihydrogenation reaction, and it exhibited interesting thiophene and carbon monoxide resistance in this transformation because interactions with these poisons are weakened by the configuration of the encaged single platinum atoms.

Low-dose IL-2 therapy limits the reduction in absolute numbers of peripheral lymphocytes in systemic lupus erythematosus patients with infection.

BACKGROUND: Systemic lupus erythematosus (SLE) is a heterogeneous autoimmune disorder characterized by disturbed cellular and humoral immune responses. Dysregulations of immune system and immunosuppressive medications predispose SLE patients to infection. This study aims to investigate the alterations and absolute concentrations of lymphocyte subpopulations in SLE patients with different infection and their responses of low-dose IL-2 therapy. METHODS: A total of 333 patients with SLE without recent infection, 162 patients suffering infection, and age and sex-matched 132 healthy controls (HCs) were recruited. Of them, 54 SLE patients (including 41 non-infected group and 13 infected group) received a 5-day course of low-dose IL-2 administration at a dose of 0.5 million IU per day. Lymphocyte subpopulations were analyzed by flow cytometry. RESULTS: Patients with SLE had lower levels of lymphocyte subpopulations in peripheral blood such as T, B, NK, CD4 + T, CD8+ T, Th1, Th2, Th17, and Treg cells, and the reduction in these cells was more obvious in patients with infection (p <.05 to p <.01). Low-dose IL-2 effectively expanded T (p <.001), B (p <.001), CD4 + T (p <.01), CD8 + T (p <.001), Th1 (p <.01), Th17 (p <.1), and Treg cells (p <.01) of SLE patients, these cells were comparable to that of HCs after the IL-2 treatment. CONCLUSIONS: Patients with SLE had insufficiency of circulating lymphocyte subsets. This phenomenon was more obverse in those accompanying infection, suggesting the low concentration of lymphocytes may be used as indicators of high infection risk in SLE patients. Low-dose IL-2 induced expansion of Treg cells and NK cells, which may contribute to the restoration of immune homeostasis in SLE patients.

A Comparison of Photoprotective Mechanism in Different Light-Demanding Plants Under Dynamic Light Conditions.

Light intensity is highly heterogeneous in nature, and plants have evolved a series of strategies to acclimate to dynamic light due to their immobile lifestyles. However, it is still unknown whether there are differences in photoprotective mechanisms among different light-demanding plants in response to dynamic light, and thus the role of non-photochemical quenching (NPQ), electron transport, and light energy allocation of photosystems in photoprotection needs to be further understood in different light-demanding plants. The activities of photosystem II (PSII) and photosystem I (PSI) in shade-tolerant species Panax notoginseng, intermediate species Polygonatum kingianum, and sun-demanding species Erigeron breviscapus were comparatively measured to elucidate photoprotection mechanisms in different light-demanding plants under dynamic light. The results showed that the NPQ and PSII maximum efficiency (F v'/F m') of E. breviscapus were higher than the other two species under dynamic high light. Meanwhile, cyclic electron flow (CEF) of sun plants is larger under transient high light conditions since the slope of post-illumination, P700 dark reduction rate, and plastoquinone (PQ) pool were greater. NPQ was more active and CEF was initiated more readily in shade plants than the two other species under transient light. Moreover, sun plants processed higher quantum yield of PSII photochemistry (ΦPSII), quantum yield of photochemical energy conversion [Y(I)], and quantum yield of non-photochemical energy dissipation due to acceptor side limitation (Y(NA), while the constitutive thermal dissipation and fluorescence (Φf,d) and quantum yield of non-photochemical energy dissipation due to donor side limitation [Y(ND)] of PSI were higher in shade plants. These results suggest that sun plants had higher NPQ and CEF for photoprotection under transient high light and mainly allocated light energy through ΦPSII and ΦNPQ, while shade plants had a higher Φf,d and a larger heat dissipation efficiency of PSI donor. Overall, it has been demonstrated that the photochemical efficiency and photoprotective capacity are greater in sun plants under transient dynamic light, while shade plants are more sensitive to transient dynamic light.

Clemastine Inhibits the Biofilm and Hemolytic of Staphylococcus aureus through the GdpP Protein.

Staphylococcus aureus poses a significant threat to human health due to its virulence and multidrug resistance. In addition, recalcitrant biofilm formation of S. aureus often results in chronic infection and the treatment tolerance toward the traditional antibiotics. Thus, the development of novel antimicrobial agents capable to inhibit or eradicate S. aureus biofilm formation does matter. Here, we demonstrated that clemastine showed slight bacteriostatic activity and enhanced the antibacterial activity of oxacillin against S. aureus. Moreover, the dramatic inhibition of biofilm formation was found in clinical S. aureus strains by clemastine. Clemastine inhibited the release of eDNA during the biofilm formation and decreased the S. aureus hemolytic activity. Moreover, the S. aureus SA113 treated with clemastine displayed the decreased transcriptional level of the biofilm formation relevant genes (fnbB, icaA, and icaB), virulence genes (hlg, hld, lukde, lukpvl, beta-PSM, delta-PSM, and cap5A), and the regulatory genes agrA. The proteomics analysis of SA113 treated with clemastine demonstrated the significant changes in levels of biofilm-related proteins (stress response regulators ClpB and GroS, ATP-binding proteins, and urease metabolism), virulence-related proteins (SspA, superantigen, and VWbp), and methicillin resistance-related proteins (glutamine metabolism). The genetic mutations on gdpP (cyclic di-AMP phosphodiesterase) were found in the clemastine-induced tolerant derivative isolate by whole-genome sequencing. Furthermore, the interaction between clemastine and GdpP protein was demonstrated by the molecular docking, gdpP overexpression experiment, and thermal stability assay. Conclusively, clemastine might exert its inhibitory effects against the biofilm formation and hemolysis in S. aureus through targeting GdpP protein. IMPORTANCE The biofilm formation, which protects bacteria from stresses, including antibiotics and host immune responses, can be commonly found in clinical S. aureus isolates worldwide. Treatment failure of traditional antibiotics in biofilm-associated S. aureus infections remains a serious challenge. The novel anti-biofilm drug is urgently needed to address the looming crisis. In this study, clemastine, which is a histamine receptor H1 (HRH1) antagonist, was found to have a novel role of the significant inhibition against the biofilm formation and hemolytic activity of S. aureus and enhanced antibacterial activity against S. aureus when used in combination with oxacillin by targeting the GdpP protein. The discovery of this study identified novel use and mechanism of action of clemastine as a potential anti-biofilm drug for clinical application for S. aureus infectious.

Lapatinib Acts against Biofilm Formation and the Hemolytic Activity of Staphylococcus aureus.

Biofilm formation and hemolytic activity are closely related to the pathogenesis of Staphylococcus aureus infections. Herein, we show that lapatinib (12.5 µM) significantly inhibits biofilm formation and hemolytic activity of both methicillin-sensitive S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) isolates. Using quantitative reverse transcription PCR, we found that the RNA levels of transcriptional regulatory genes (RNAIII, agrA, agrC, saeR, and saeS), biofilm-formation-related genes (atl, cidA, clfA, clfB, and icaA), and virulence-related genes (cap5A, hla, hld, hlg, lukDE, lukpvl-S, staphopain B, alpha-3 PSM, beta PSM, and delta PSM) of S. aureus decreased after 6 h treatment with lapatinib. Wild-type S. aureus isolates were continuously cultured in vitro in the presence of increasing concentrations of lapatinib for about 140 days. Subsequently, S. aureus isolates with reduced susceptibility to lapatinib (the inhibitory effect of lapatinib on the biofilm formation of these S. aureus isolates was significantly weakened) were selected. Mutations in the genomes of S. aureus isolates with reduced susceptibility to lapatinib were detected by whole-genome sequencing. We identified four genes with mutations: three genes with known functions (membrane protein, pyrrolidone-carboxylate peptidase, and sensor histidine kinase LytS, respectively) and one gene with unknown function (hypothetical protein). In conclusion, this study indicates that lapatinib significantly inhibits biofilm formation and the hemolytic activity of S. aureus.

Responses of Linear and Cyclic Electron Flow to Nitrogen Stress in an N-Sensitive Species Panax notoginseng.

Nitrogen (N) is a primary factor limiting leaf photosynthesis. However, the mechanism of N-stress-driven photoinhibition of the photosystem I (PSI) and photosystem II (PSII) is still unclear in the N-sensitive species such as Panax notoginseng, and thus the role of electron transport in PSII and PSI photoinhibition needs to be further understood. We comparatively analyzed photosystem activity, photosynthetic rate, excitation energy distribution, electron transport, OJIP kinetic curve, P700 dark reduction, and antioxidant enzyme activities in low N (LN), moderate N (MN), and high N (HN) leaves treated with linear electron flow (LEF) inhibitor [3-(3,4-dichlorophenyl)-1,1-dimethyl urea (DCMU)] and cyclic electron flow (CEF) inhibitor (methyl viologen, MV). The results showed that the increased application of N fertilizer significantly enhance leaf N contents and specific leaf N (SLN). Net photosynthetic rate (P n) was lower in HN and LN plants than in MN ones. Maximum photochemistry efficiency of PSII (F v/F m), maximum photo-oxidation P700+ (P m), electron transport rate of PSI (ETRI), electron transport rate of PSII (ETRII), and plastoquinone (PQ) pool size were lower in the LN plants. More importantly, K phase and CEF were higher in the LN plants. Additionally, there was not a significant difference in the activity of antioxidant enzyme between the MV- and H2O-treated plants. The results obtained suggest that the lower LEF leads to the hindrance of the formation of ΔpH and ATP in LN plants, thereby damaging the donor side of the PSII oxygen-evolving complex (OEC). The over-reduction of PSI acceptor side is the main cause of PSI photoinhibition under LN condition. Higher CEF and antioxidant enzyme activity not only protected PSI from photodamage but also slowed down the damage rate of PSII in P. notoginseng grown under LN.