Relationship between negative air ion and PM2.5 in Quercus variabilis under natural conditions.

In recent years, PM2.5 pollution has become a most important source of air pollution. Prolonged exposure to high PM2.5 concentrations can give rise to severe health issues. Negative air ion (NAI) is an important indicator for measuring air quality, which is collectively known as the 'air vitamin'. However, the intricate and fluctuating meteorological conditions and vegetation types result in numerous uncertainties in the correlation between PM2.5 and NAI. In this study, we collected data on NAI, PM2.5, and meteorological elements through positioning observation during the period of June to September in 2019 and 2020 under the condition of relatively constant leaf area in Quercus variabilis forest, a typical forest in warm temperate zones. We investigated the spatiotemporal variation of PM2.5 and NAI under consistent meteorological conditions, established the correlation between PM2.5 and NAI, and explicated the impact mechanism of PM2.5 on NAI in natural conditions. The results showed that NAI decreased exponentially with the increases in natural PM2.5, with a significant negative correlation (y=1148.79x-0.123). The decrease rates of NAI in PM2.5 concentrations of 0-20, 20-40, 40-80, 80-100 and 100-120 µg·m-3 were 40.1%, 36.2%, 9.4%, 2.4%, 5.1% and 6.8%, respectively. Results of the sensitivity analysis showed that the PM2.5 concentration range of 0-40 µg·m-3 was the sensitive range that affected NAI. Our findings could provide a scientific basis for better understanding the response mechanisms of NAI to environmental factors.

Effect of light intensity on negative air ion under phytotron control.

Negative air ion (NAI) is an important index for measuring air quality and has been widely recognized to be influenced by photosynthesis processes. However, vegetation type and light intensity are also known to impact NAI, contributing to significant uncertainties in the relationship between light and NAI. In this paper, we selected Pinus bungeana, Platycladus orientalis and Buxus sinica as research subjects and obtained their NAI, light intensity, and meteorological data through synchronous observation under the relatively stable condition of the phytotron. We analyzed the change characteristics of NAI and the difference of NAI production ability in needle and broadleaf vegetation under different light intensities. Finally, we determined the relationship and underlying mechanism governing light intensity and NAI using diverse tree species. The results showed that the influence of light on NAI was significant. In the environment without vegetation, the influence of different light intensities on NAI was not significant, and the mean NAI concentration was 310 ions·cm-3. Conversely, in the presence of vegetation, NAI showed a "single-peak" trend with increasing light intensity. The NAI concentration of the three tree species was significantly higher than under different light intensities when vegetation was not present. The NAI promoting ability of P. bungeana was the highest (675 ions·cm-3), followed by P. orientalis (478 ions·cm-3) and B. sinica (430 ions·cm-3), which increased by 117.5%, 53.9% and 38.6% compared to the environment without vegetation. The NAI growth rate was significantly different between needle and broadleaf vegetation based on the specific tridimensional green biomass. Additionally, the NAI growth rates of P. bungeana and P. orientalis were 647 and 295 ions·cm-3·m-3, respectively, which were 3.06 and 1.39 times that of B. sinica (211 ions·cm-3·m-3). The piecewise equation fitting effect of NAI and light intensity was better for different tree species, the determination coefficients (R2) of P. bungeana, P. orientalis and B. sinica were 0.926, 0.916 and 0.880, and the root mean square errors (RMSE) were 7.157, 6.008 and 5.389 ion·cm-3, respectively. Altogether, our study provides a theoretical basis as well as technical support for the construction of healthy vegetation stands, the selection of preferred tree species, and the optimization of vegetation models, and promotes air quality and the provision of ecosystem functions and services.

[Variation characteristics of plant electrical signal and their relationship with negative air ion under different light intensities.] / ä¸åŒå ‰ç §å¼ºåº¦ä¸‹æ¤ç‰©ç”µä¿¡å·å˜åŒ–ç‰¹å¾åŠå ¶ä¸Žç©ºæ°”è´Ÿç¦»å­çš„å ³ç³».

Negative air ion (NAI) is an essential indicator for measuring air cleanliness of a given area, with vital role in regulating psychological and physiological functions of human body. The photoelectric effect is an important source and influencing factor for the generation of NAI during photosynthesis, but the photoelectric effect is extremely weak and difficult to monitor. Plant electrical signal is an important indicator that indirectly reflects photoelectric effect. Previous studies mostly focused on the spatiotemporal variation of NAI in different forest communities and its relationship with meteorological factors. At present, there is little research on NAI and plant electrical signal. In this study, we explored the effect of different light intensities (0, 150, 300, 500, 700, 800, 1000 and 1200 µmol·m-2·s-1) on characteristics of the plant electrical signal and its relationship with negative air ion, with Pinus bungeana as the research object. The results showed that the intensity of plant electrical signal increased significantly with the increases of light intensity in the illumination range of 0-700 µmol·m-2·s-1. When light intensity reached 700 µmol·m-2·s-1, plant electrical signal activity reached the highest level, and plant was inhibited by light when light intensity increased further, with plant electrical signal activity decreased. The frequency-domain parameters (edge frequency, gravity frequency, power spectrum entropy and power spectrum peak) of plant electrical signals were significantly correlated with NAI. The correlation coefficient between edge frequency (E) and NAI was the highest, the relationship between them was NAI=30.981E+168.814 (R2=0.54), and the mean square error was 52.203. There was a significant correlation between plant electrical signals and NAI, which could characterize the change rule of NAI, and provide scientific evidence for further understanding the contribution potential and production mechanism of forest to NAI.

Glucose-6-phosphate dehydrogenase is required for extracellular polysaccharide production, cell motility and the full virulence of Xanthomonas oryzae pv. oryzicola.

Glucose-6-phosphate dehydrogenase (Zwf) catalyzes conversion of glucose 6-phosphate into gluconate 6-phosphate for Entner-Doudoroff (ED) and pentose phosphate pathways in living organisms. However, it is unclear whether the Zwf-coding gene is involved in pathogenesis of phytopathogenic bacterium. In this report, we found that deletion mutation in zwf of Xanthomonas oryzae pv. oryzicola (Xoc), led the pathogen unable to effectively utilize glucose, sucrose, fructose, mannose and galactose for growth. The transcript level of zwf was strongly induced by glucose, sucrose, fructose, mannose and galactose than that by the NY medium (non sugar). The deletion mutagenesis in zwf also altered the transcript level of key genes, such as rpfF, rpfG and clp, in diffusible signal factor (DSF)-signaling network. In addition, the deletion mutation in zwf impaired bacterial virulence and growth capability in rice leaves, reduced bacterial cell motility and extracellular polysaccharide (EPS) production. The lost properties mentioned above in the zwf deletion mutant were completely restored to the wild-type level by the presence of zwf in trans. All these results suggest that zwf is required for the full virulence of Xoc in rice leaves by involving carbohydrate metabolisms that impact bacterial DSF-signaling network.

HrcT is a key component of the type III secretion system in Xanthomonas spp. and also regulates the expression of the key hrp transcriptional activator HrpX.

The type III secretion system (T3SS), encoded by hrp (hypersensitive response and pathogenicity) genes in Gram-negative phytopathogenic bacteria, delivers repertoires of T3SS effectors (T3SEs) into plant cells to trigger the hypersensitive response (HR) in nonhost or resistant-host plants and promote pathogenicity in susceptible plants. The expression of hrp genes in Xanthomonas is regulated by two key regulatory proteins, HrpG and HrpX. However, the interactions between hrp gene products in directing T3SE secretion are largely unknown. Here we demonstrated that HrcT of X. oryzae pv. oryzicola functions as a T3SS component and positively regulates the expression of hrpX. Transcription of hrcT occurs via two distinct promoters; one (T1) is with the hrpB operon and the second (T3) within hrpB7 Via either promoter T1 or T3, the defect in Hrp phenotype by hrcT deletion was corrected in the presence of hrcT only from Xanthomonas species but not from other phytopathogenic bacteria. An N-terminally truncated HrcT was able to bind the hrpX promoter and activate the expression of hrpX, supporting that HrcT is a positive regulator of hrpX. A revised model showing the regulatory interactions between HrcT, HrpX, and HrpG is proposed.

Preparation of the thienopyridine derivatives loaded liposomes and study on the effect of compound-lipid interaction on release behavior.

The article describes characterization of two liposome formulations containing thienopyridine derivatives, namely TP-58 and TP-67. By preparing the liposomes, the concentration of the two compounds in ultrapure water was increased up to three orders of magnitude. After i.v. administration of the liposomes in rats, the initial compound plasma concentrations were enhanced more than fifty times relative to that after i.g. administration of the compound suspensions. It was found out that the release rate of TP-67 from the liposome both in vitro and in vivo was not significantly different from that of TP-58. TP-58 was more lipophilic than TP-67 according to partition coefficiency, and TP-67 had greater polarity than TP-58 based on polar surface area (PSA). With DSC, it was found out that the interaction magnitude between TP-67 and the lipid bilayer was not significantly different from that between TP-58 and the lipid bilayer, which accounted for the similarity of the two compounds in release rate both in vitro and in vivo. It indicated liposome can be used as a potential carrier for broading the application of TP-58 and TP-67. Interaction between the thienopyridine derivatives and the lipid bilayer is probably the decisive factor for compound release from the liposomes.

A systemic administration of liposomal curcumin inhibits radiation pneumonitis and sensitizes lung carcinoma to radiation.

Radiation pneumonitis (RP) is an important dose-limiting toxicity during thoracic radiotherapy. Previous investigations have shown that curcumin is used for the treatment of inflammatory conditions and cancer, suggesting that curcumin may prevent RP and sensitize cancer cells to irradiation. However, the clinical advancement of curcumin is limited by its poor water solubility and low bioavailability after oral administration. Here, a water-soluble liposomal curcumin system was developed to investigate its prevention and sensitizing effects by an intravenous administration manner in mice models. The results showed that liposomal curcumin inhibited nuclear factor-κB pathway and downregulated inflammatory factors including tumor necrosis factor-α, interleukin (IL)-6, IL-8, and transforming growth factor-ß induced by thoracic irradiation. Furthermore, the combined treatment with liposomal curcumin and radiotherapy increased intratumoral apoptosis and microvessel responses to irradiation in vivo. The significantly enhanced inhibition of tumor growth also was observed in a murine lung carcinoma (LL/2) model. There were no obvious toxicities observed in mice. The current results indicate that liposomal curcumin can effectively mitigate RP, reduce the fibrosis of lung, and sensitize LL/2 cells to irradiation. This study also suggests that the systemic administration of liposomal curcumin is safe and deserves to be investigated for further clinical application.

Ketoglutarate transport protein KgtP is secreted through the type III secretion system and contributes to virulence in Xanthomonas oryzae pv. oryzae.

The phytopathogenic prokaryote Xanthomonas oryzae pv. oryzae is the causal agent of bacterial leaf blight (BB) of rice and utilizes a type III secretion system (T3SS) to deliver T3SS effectors into rice cells. In this report, we show that the ketoglutarate transport protein (KgtP) is secreted in an HpaB-independent manner through the T3SS of X. oryzae pv. oryzae PXO99(A) and localizes to the host cell membrane for α-ketoglutaric acid export. kgtP contained an imperfect PIP box (plant-inducible promoter) in the promoter region and was positively regulated by HrpX and HrpG. A kgtP deletion mutant was impaired in bacterial virulence and growth in planta; furthermore, the mutant showed reduced growth in minimal media containing α-ketoglutaric acid or sodium succinate as the sole carbon source. The reduced virulence and the deficiency in α-ketoglutaric acid utilization by the kgtP mutant were restored to wild-type levels by the presence of kgtP in trans. The expression of OsIDH, which is responsible for the synthesis of α-ketoglutaric acid in rice, was enhanced when KgtP was present in the pathogen. To our knowledge, this is the first report demonstrating that KgtP, which is regulated by HrpG and HrpX and secreted by the T3SS in Xanthomonas oryzae pv. oryzae, transports α-ketoglutaric acid when the pathogen infects rice.

Fructose-bisphophate aldolase exhibits functional roles between carbon metabolism and the hrp system in rice pathogen Xanthomonas oryzae pv. oryzicola.

Fructose-bisphophate aldolase (FbaB), is an enzyme in glycolysis and gluconeogenesis in living organisms. The mutagenesis in a unique fbaB gene of Xanthomonas oryzae pv. oryzicola, the causal agent of rice bacterial leaf streak, led the pathogen not only unable to use pyruvate and malate for growth and delayed its growth when fructose was used as the sole carbon source, but also reduced extracellular polysaccharide (EPS) production and impaired bacterial virulence and growth in rice. Intriguingly, the fbaB promoter contains an imperfect PIP-box (plant-inducible promoter) (TTCGT-N(9)-TTCGT). The expression of fbaB was negatively regulated by a key hrp regulatory HrpG and HrpX cascade. Base substitution in the PIP-box altered the regulation of fbaB with the cascade. Furthermore, the expression of fbaB in X. oryzae pv. oryzicola RS105 strain was inducible in planta rather than in a nutrient-rich medium. Except other hrp-hrc-hpa genes, the expression of hrpG and hrpX was repressed and the transcripts of hrcC, hrpE and hpa3 were enhanced when fbaB was deleted. The mutation in hrcC, hrpE or hpa3 reduced the ability of the pathogen to acquire pyruvate and malate. In addition, bacterial virulence and growth in planta and EPS production in RΔfbaB mutant were completely restored to the wild-type level by the presence of fbaB in trans. This is the first report to demonstrate that carbohydrates, assimilated by X. oryzae pv. oryzicola, play critical roles in coordinating hrp gene expression through a yet unknown regulator.

Improved solubility and pharmacokinetics of PEGylated liposomal honokiol and human plasma protein binding ability of honokiol.

PEGylated liposomal honokiol had been developed with the purpose of improving the solubility and pharmacokinetics compared with free honokiol. Human plasma protein binding ability of honokiol was also investigated. PEGylated liposomal honokiol was prepared by thin film evaporation-sonication method. Its mean particle size was 98.68 nm, mean zeta potential was -20.6 mV and encapsulation efficiency were 87.68±1.56%. The pharmacokinetics of PEGylated liposomal honokiol was studied after intravenous administration in Balb/c mice. There were significant differences of parameters T(1/2ß) and AUC(0→∞) between them and liposome lengthened T(1/2ß) and AUC(0→∞) values. The mean T(1/2ß) value of PEGylated liposomal honokiol and free honokiol were 26.09 min and 13.46 min, respectively. The AUC(0→∞) ratio of PEGylated liposomal honokiol to free honokiol was about 1.85-fold (219.24 µg/mL min/118.68 µg/mL min) (P=0.000). Examination of protein binding ability showed that honokiol with 0.5, 8.0 and 20 µg/mL concentrations in human plasma achieved the percent of bound between 60% and 65%. The results suggested that PEGylated liposomal honokiol improved the solubility, increased the drug concentration in plasma, and withstanded the clearance. Besides, the percent of protein bound of honokiol in human plasma was between 60% and 65%.

Synthesis, structural and in vitro studies of well-dispersed monomethoxy-poly(ethylene glycol)-honokiol conjugate micelles.

Honokiol, an active principle extracted from Magnolia officinalis, has great potential as a cancer treatment. However, its poor water solubility greatly hampers its delivery to the tumor sites at an effective concentration. In this study, an amphiphilic polymer-drug conjugate was successfully prepared by condensation of low molecular weight monomethoxy-poly(ethylene glycol) (MPEG)-2000 with honokiol (HK) through an ester linkage to increase the hydrophilicity of honokiol. The MPEG-honokiol (MPEG-HK) conjugate prepared formed nano-sized micelles, with a mean particle size of less than 20 nm (MPEG-HK, 360 µg ml(-1)) in water, which could be well dispersed in water. The nanoparticles obtained were characterized by particle size distribution, morphology and zeta potential. The stability and hydrolysis profile of the polymeric pro-drug in phosphate-buffered saline (PBS) and plasma were also studied and the results showed that only 20% of the conjugated honokiol was released in 2.0 h in beagle dog plasma, while in PBS the time required to reach 20% of honokiol release was >200 h. Meanwhile, the inhibitory activity of the honokiol conjugate was found to be retained in vitro against LL/2 cell lines with an IC50 value of 10.7 µg ml(-1). These results suggest that the polymer-drug conjugate provides a potential new approach to hydrophobic drugs, such as honokiol, in formulation design.

Schistosoma japonicum: efficient and rapid purification of the tetraspanin extracellular loop 2, a potential protective antigen against schistosomiasis in mammalian.

The extracellular loop 2 of a tetraspanin from Schistosoma japonicum (Sj-TSP-2) is homologous to Schistosoma mansoni TSP-2. In our initial study, Sj-TSP-2 is an identical antigen against schistosomiasis caused by S. japonicum. Through the pET32 vector system and nickel (Ni)-absorbed chelating Sepharose, Sj-TSP-2 was expressed and purified as a soluble fusion constructed with an N-terminal thioredoxin-His(6)-EK protease site tag (Trx-TSP-2). In phosphate buffer (PB) with a low concentration of imidazole, the Trx-TSP-2 fusion protein was efficiently cleaved by enterokinase (EK). Sj-TSP-2 was isolated and enriched using cobalt (Co)-absorbed chelating Sepharose and HiTrap SP column. Character of the protein was analyzed via animal experiments and then clinical trials. The purification approach yielded pure Sj-TSP-2, which will provide feasible advices for discovering vaccines against schistosomiasis.

[SKLB-102 inhibits acute hepatitis induced by concanavalin A in mice].

OBJECTIVE: To test the effect of 5-(4-methoxybenzylidene)-2-thioxo-dihydropyrimidine-4, 6 (1H, 5H)-dione (SKLB-102) on acute hepatic inflammatory induced by concanavalin A (ConA) in mice. METHODS: The inhibitive effect of SKLB-102 on RAW264.7 cell migration induced by recombinant rat monocyte chemotactic protein-1 (MCP-1) was tested. The serum from the ConA-treated mice was collected after intragastric administration of SKLB-102 at the dose of 50 mg/kg bodyweight. The serum AST and ALT were determined by an automatic analyzer, and the serum TNF-alpha was determined with enzyme-linked immunosorbent assay (ELISA) kits. The liver samples were fixed in 10% formalin, embedded in paraffin, sectioned and then stained with hematoxylin and eosin for histological examinations. RESULTS: SKLB-102 markedly reduced cell migrations, successfully reduced serum AST, ALT and down-regulated TNF-alpha. CONCLUSION: SKLB-102 is likely to suppress the occurrence of Con A-induced hepatitis by suppressing macrophages migration and TNF-alpha releases.