The transcription factor PbrMYB24 regulates lignin and cellulose biosynthesis in stone cells of pear fruits.

Lignified stone cell content is a key factor used to evaluate fruit quality, influencing the economic value of pear (Pyrus pyrifolia) fruits. However, our understanding of the regulatory networks of stone cell formation is limited due to the complex secondary metabolic pathway. In this study, we used a combination of co-expression network analysis, gene expression profiles, and transcriptome analysis in different pear cultivars with varied stone cell content to identify a hub MYB gene, PbrMYB24. The relative expression of PbrMYB24 in fruit flesh was significantly correlated with the contents of stone cells, lignin, and cellulose. We then verified the function of PbrMYB24 in regulating lignin and cellulose formation via genetic transformation in homologous and heterologous systems. We constructed a high-efficiency verification system for lignin and cellulose biosynthesis genes in pear callus. PbrMYB24 transcriptionally activated multiple target genes involved in stone cell formation. On the one hand, PbrMYB24 activated the transcription of lignin and cellulose biosynthesis genes by binding to different cis-elements [AC-I (ACCTACC) element, AC-II (ACCAACC) element and MYB-binding sites (MBS)]. On the other hand, PbrMYB24 bound directly to the promoters of PbrMYB169 and NAC STONE CELL PROMOTING FACTOR (PbrNSC), activating the gene expression. Moreover, both PbrMYB169 and PbrNSC activated the promoter of PbrMYB24, enhancing gene expression. This study improves our understanding of lignin and cellulose synthesis regulation in pear fruits through identifying a regulator and establishing a regulatory network. This knowledge will be useful for reducing the stone cell content in pears via molecular breeding.

Importance of core microRNA pathway genes and microRNAs associated with the defense of Odontotermes formosanus (Shiraki) against Serratia marcescens infection.

MicroRNAs (miRNAs) are noncoding small regulatory RNAs involved in diverse biological processes. Odontotermes formosanus (Shiraki) is a polyphagous pest that causes economic damage to agroforestry. Serratia marcescens is a bacterium with great potential for controlling this insect. However, knowledge about the miRNA pathway and the role of miRNAs in O. formosanus defense against SM1 is limited. In this study, OfAgo1, OfDicer1 and OfDrosha were differentially expressed in different castes and tissues. SM1 infection affected the expression of all three genes in O. formosanus. Then, we used specific double-stranded RNAs to silence OfAgo1, OfDicer1 and OfDrosha. Knockdown of these genes enhanced the virulence of SM1 to O. formosanus, suggesting that miRNAs were critical in the defense of O. formosanus against SM1. Furthermore, we sequenced miRNAs from SM1-infected and uninfected O. formosanus. 33 differentially expressed (DE) miRNAs were identified, whereby 22 were upregulated and 11 were downregulated. Finally, the miRNA-mRNA networks were constructed, which further suggested the important role of miRNAs in the defense of O. formosanus against SM1. Totally, O. formosanus miRNA core genes defend against SM1 infection by regulating miRNA expression. This study elucidates the interactions between O. formosanus and SM1 and provides new theories for biological control.

ß-Cyclodextrin/Azobenzene Microspheres Loaded with Paraquat Are Safe and Effective.

Although paraquat is a widely used herbicide, it is toxic to humans if ingested or absorbed through an open wound. To improve the safety of paraquat, a new formulation of paraquat based on photoresponsive polymers was exploited. Photoresponsive ß-cyclodextrin polymer microspheres (AZO-CD) were synthesized via a host-guest interaction between ß-cyclodextrin and azobenzene. AZO-CD were characterized by Fourier transform infrared spectrometry, circular dichroism, ultraviolet (UV) spectrophotometry, and thermogravimetric analysis, and their photoresponsiveness was also evaluated. AZO-CD were used to load paraquat, which yielded photoresponsive paraquat-loaded microspheres. For the paraquat-loaded microspheres, irradiation with UV light or sunlight induced the isomerization of azobenzene into the cis form. Then, the cis-azobenzene was liberated from the cavities of the ß-cyclodextrin. The paraquat-loaded microspheres released paraquat continuously over time. Furthermore, under UV light, the herbicidal capacity of the paraquat-loaded microspheres against barnyard grass was comparable to that of free paraquat at the same dose. Our findings show that loading paraquat into AZO-CD provides a safe and environmentally friendly herbicide formulation.

Fabrication a controlled-release pesticide for improving UV-shielding properties and reducing toxicity via coating polydopamine.

Controlled-release formulations (CRFs) have potential applications in modern agriculture, for it can not only prolong the duration of agrochemicals but also alleviate the adverse effect on non-target organism. In this study, we constructed pyraclostrobin@SiO2@polydopamine microcapsule (Pyr@SiO2@PDA MC). The resulting microcapsule is a near-rod shape (about 1.15 µm), which has a drug-loading efficiency of 55%. Fourier transform infrared (FTIR) and thermogravimetric analysis (TG) revealed the successful entrapment of the pesticide. The coating of polydopamine (PDA) endowing the microcapsule with superior UV-shielding properties than pyraclostrobin@SiO2 microcapsule (Pyr@SiO2 MC). Compared with pyraclostrobin emulsifiable concentrate (EC), the Pyr@SiO2@PDA MC exhibited 9.07-, 5.50-, 4.93- and 4.16-fold higher fungicidal activity against Rice blast fungus (Pyricularia oryzae) at concentrations of 0.5, 1, 2 and 4 mg/L. Moreover, acute toxicity tests demonstrated that the sample on zebrafish with lower toxicity on the first day. These results showed that the obtained microcapsule may process broader application potential in agriculture.

Cytomegalovirus Shedding in Healthy Seropositive Female College Students: A 6-Month Longitudinal Study.

Background: Cytomegalovirus (CMV) establishes a lifelong latent infection after primary infection and may reactivate periodically, with the shedding of infectious virus in body fluids. To better understand the prevalence and shedding model of CMV in immunocompetent seropositive women of childbearing age, a 6-month longitudinal study was conducted in healthy female college students. Methods: A total of 102 nonpregnant female college students aged 18-30 years were enrolled and followed up every 2 weeks for 6 months. Saliva and urine samples were collected at each visit. Serum samples were collected at the first and last visits. Results: All participants were positive for anti-CMV immunoglobulin G (IgG) at entry. During the 6-month period, 29.4% of participants (30 of 102) shed CMV intermittently in saliva or urine. At each visit, the CMV shedding prevalence varied from 2.0% to 10.4% and presented only in 1 bodily fluid. The viral load was low and did not induce marked antibody increases. The baseline anti-CMV IgG level was not found to be associated with viral shedding. Conclusions: CMV shedding in saliva and urine is common and intermittent and does not stimulate an anamnestic antibody response in seropositive immunocompetent women of childbearing age with a low risk of exposure to exogenous infectious sources.

Compound pesticide controlled release system based on the mixture of poly(butylene succinate) and PLA.

Controlled release system has been widely developed and utilised in agriculture to optimise efficacy and minimise environmental pollution. Here, the azoxystrobin and difenoconazole compound pesticide microsphere was constructed by the solvent evaporation method. Blending poly (butylene succinate) (PBS) and poly (lactic acid) (PLA) as shells, in order to increase its entrapment efficiency and match the goal of complex synergism. The resulting microsphere processes high entrapment efficiency with a mean diameter of 7.2 µm. Acute toxicity suggested microsphere on zebrafish was moderate toxicity. Comparative studies revealed that the microsphere had a longer period of sustained release than difenoconazole-azoxystrobin (5:8) 32.5% w/v suspension concentrate (SC). In addition, the concentration ratio of active ingredients closed to the optimum compound stoichiometry, which can achieve the objective of improving the efficacy of the pesticides. These results demonstrated that such a compound pesticide microsphere delivery system may be a considerable potential for further exploration.

[Short-term curative effect of ribavirin combination therapy with pegylated interferon alfa-2a vs. interferon alfa-2a in patients with chronic hepatitis C].

OBJECTIVE: To perform a retrospective cohort study in order to determine the differences in short-term curative effect of ribavirin in combination with interferon alfa (IFNa)-2a vs. pegylated (Peg)-IFNa-2a in patients with chronic hepatitis C (CHC). METHODS: One-hundred-and-eighty-eight treatment of the CHC patients who were administered combination therapy of ribavirin with IFNa from 2010 to 2012. One-hundred-and-thirty-three of the patients received the therapy with IFNa-2a and the remaining 55 received Peg-IFNa-2a. Hepatitis C virus (HCV) load and levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured at treatment weeks 4, 12, 24, and 48. Adverse reactions were recorded. Differences between the groups were assessed by statistical analysis. RESULTS: The patients in the Peg-IFNa-2a group and the IFNa-2a group showed no significant difference in sex distribution, age, smoking habits, or drinking habits at baseline (all P more than 0.05). Both antiviral therapies significantly reduced the HCV load and levels of ALT and AST (baseline levels vs. all treatment weeks examined, P less than 0.05); however, the reduction in the HCV load at week 4 was significantly more robust with the Peg-IFNa-2a therapy (2.96 ± 0.66) log10 IU/ ml vs. (3.47 ± 1.42)1og10 IU/ml; F =4.14, P=0.04). The Peg-IFNa-2a group also showed a significant higher rate of rapid virological response (RVR) than the IFNa-2a group (72.72% vs .57.14%; x²=4.37, P=0.04), but there were no statistically significant differences found between the two groups for early virological response rate (EVR), endpoint antiviral treatment virologic response rate (ETR), biochemical response rate, or rate of adverse reactions (all P more than 0.05). CONCLUSION: Ribavirin in combination with Peg-IFNa-2a produces a better RVR than in combination with IFNa-2a .Yet, the EVR, ETR, biochemical response rate, and rate of adverse reactions is similar for the two forms of IFNa-2a. Further studies are required to determine the potential superiority of Peg-IFNa-2a for a long-term curative effect.

The Function of Termicin from Odontotermes formosanus (Shiraki) in the Defense against Bacillus thuringiensis (Bt) and Beauveria bassiana (Bb) Infection.

Odontotermes formosanus (Shiraki) is a subterranean termite species known for causing severe damage to trees and structures such as dams. During the synergistic evolution of O. formosanus with pathogenic bacteria, the termite has developed a robust innate immunity. Termicin is a crucial antimicrobial peptide in termites, significantly contributing to the defense against external infections. Building upon the successful construction and expression of the dsRNA-HT115 engineering strains of dsOftermicin1 and dsOftermicin2 in our laboratory, this work employs the ultrasonic breaking method to establish an inactivated dsOftermicins-HT115 technological system capable of producing a substantial quantity of dsRNA. This approach also addresses the limitation of transgenic strains which cannot be directly applied. Treatment of O. formosanus with dsOftermicins produced by this method could enhance the virulence of both Bt and Bb to the termites. This study laid the theoretical groundwork for the development of novel termite immunosuppressants and for the advancement and application of termite biological control strategies.

Effect of B. subtilis in simulated acid red soil on the corrosion behavior of X80 pipeline steel.

The eastern section of China's West-east gas transmission project is laid in acidic red soil. NRB are widespread in soils and play an important role in metal corrosion. In this article, the corrosion failure behavior and mechanism of X80 pipeline steel under the action of NRB in simulated acidic soil were studied. It was found that the biofilm of B. subtilis had significant inhibitory on the overall corrosion of X80 steel. Electrochemical results prove that the corrosion rate of the sterile group after 14 days of immersion was about 4.5 times that of the bacterial group. However, the biofilm promotes the formation of local corrosion pits. Confocal laser scanning microscopy images indicate that that the corrosion pit depth of the bacterial group (46.1 µm) was three times that of the bacterial-free group (15.7 µm) after 14 days. The pH of the acidic environment was slightly improved by B. subtilis. XPS results proved that B. subtilis complicates the corrosion products of X80 steel through its nitrate reduction ability and metabolism.

Extracellular electron transfer routes in microbiologically influenced corrosion of X80 steel by Bacillus licheniformis.

Bacillus licheniformis can take up electrons from X80 steel for nitrate reduction and accelerate corrosion. In this work, the routes B. licheniformis adopts for extracellular electron transfer (EET) were revealed using electrochemical tests, fluorescence staining, high performance liquid chromatography (HPLC) and weight loss tests, and their kinetics were also analyzed in detail. The results showed that B. licheniformis can take up electrons from steel surface via three routes: direct electron transfer by cytochromes, direct electron transfer by flavin-bound cytochromes and mediated electron transfer by diffusible flavin. B. licheniformis itself can only secrete traces of riboflavin which are mainly bound to the surface cytochromes assisting electron transfer. Adding flavins can increase the bound content, and with the binding sites of cytochrome becoming saturated the rest of flavins will mediate electron transfer through diffusion even more efficiently than the bound.

Direct microbial electron uptake as a mechanism for stainless steel corrosion in aerobic environments.

Shewanella oneidensis MR-1 is an attractive model microbe for elucidating the biofilm-metal interactions that contribute to the billions of dollars in corrosion damage to industrial applications each year. Multiple mechanisms for S. oneidensis-enhanced corrosion have been proposed, but none of these mechanisms have previously been rigorously investigated with methods that rule out alternative routes for electron transfer. We found that S. oneidensis grown under aerobic conditions formed thick biofilms (∼50 µm) on stainless steel coupons, accelerating corrosion over sterile controls. H2 and flavins were ruled out as intermediary electron carriers because stainless steel did not reduce riboflavin and previous studies have demonstrated stainless does not generate H2. Strain ∆mtrCBA, in which the genes for the most abundant porin-cytochrome conduit in S. oneidensis were deleted, corroded stainless steel substantially less than wild-type in aerobic cultures. Wild-type biofilms readily reduced nitrate with stainless steel as the sole electron donor under anaerobic conditions, but strain ∆mtrCBA did not. These results demonstrate that S. oneidensis can directly consume electrons from iron-containing metals and illustrate how direct metal-to-microbe electron transfer can be an important route for corrosion, even in aerobic environments.

Study of biofilm-influenced corrosion on X80 pipeline steel by a nitrate-reducing bacterium, Bacillus cereus, in artificial Beijing soil.

The biofilm of Bacillus cereus on the surface of X80 pipeline steel was investigated from forming to shedding. Based on the observed biofilm morphology and pit analysis, it was found that B. cereus biofilm could stimulate X80 pipeline steel pitting corrosion, which was attributed to the nitrate reduction of bacteria beneath the biofilm. Electrochemical measurements and general corrosion rate results showed that B. cereus biofilm can better accelerate X80 pipeline steel corrosion compared to sterile solutions. Interestingly, the results also showed that thick biofilms had a slight tendency to inhibit the general corrosion process compared with its formation and exfoliation, which was confirmed by scanning Kelvin probe. The corrosion rate of X80 pipeline steel in artificial Beijing soil is closely related to the state of the biofilm, and nitrate reducing bacteria accelerates the occurrence of pits. The corresponding corrosion mechanisms are proposed.

Effect of alternating current and Bacillus cereus on the stress corrosion behavior and mechanism of X80 steel in a Beijing soil solution.

The effects of alternating current (AC) and Bacillus cereus (B. cereus) on the stress corrosion behavior and mechanism of X80 pipeline steel were investigated in a Beijing soil solution in this study. Both AC and B. cereus can promote the generation of pits in X80 steel. B. cereus is a type of nitrate-reducing bacteria and hence nitrate reduction occurs at the bottom of the corrosion product film or the biofilm. Meanwhile, the anode accelerates the dissolution of X80 steel and generates some pits in the local working area. The synergistic effect of AC and nitrate- reducing bacteria (NRB) promotes X80 steel corrosion and increases its susceptibility to stress corrosion cracking (SCC).

Photostable pH-Sensitive Near-Infrared Aggregation-Induced Emission Luminogen for Long-Term Mitochondrial Tracking.

Mitochondria are crucial in the process of oxidative metabolism and apoptosis. Their morphology is greatly associated with the development of certain diseases. For specific and long-term imaging of mitochondrial morphology, we synthesized a new mitochondria-targeted near-infrared (NIR) fluorescent probe (TPE-Xan-In) by incorporating TPE with a NIR merocyanine skeleton (Xan-In). TPE-Xan-In displayed both absorption (660 nm) and emission peaks (743 nm) in the NIR region. Moreover, it showed aggregation-induced emission properties at neutral pH and specifically illuminated mitochondria with good biocompatibility, superior photostability, and high tolerance to mitochondrial membrane potential changes. With a pH-responsive unit, hydroxyl xanthene (Xan), the probe exhibited a pH-sensitive fluorescence emission in the range of pH 4.0-7.0, which indicated its potential in long-term tracking of pH and morphology changes of mitochondria in the biomedical research studies.

Facile loading of Ag nanoparticles onto magnetic microsphere by the aid of a tannic acid-Metal polymer layer to synthesize magnetic disinfectant with high antibacterial activity.

In this article, Ag nanoparticles (NPs) were easily loaded onto magnetic material through a tannic acid-metal polymer (PTA) intermedia layer to synthesize Fe3O4@PTA@Ag magnetic composite and the potential application as bactericidal agent for water disinfection was investigated. The as-obtained composite, with a Fe3O4 core of 150nm, has plenty of Ag NPs of 15nm adhered onto the PTA layer outside the core. The PTA layer, like the famous polydopamine complex, possesses excellent adhesive capacity to load more Ag NPs tightly and has specific antibacterial activity due to the numerous catechol groups. Therefore, remarkable bactericidal activity was achieved and 31.25mgL-1 of Fe3O4@PTA@Ag disinfectant could inactivate more than 99% of the tested strains within 60min. At the same time, the catechol groups also endow the PTA layer with reduction ability so that additional reductant is unnecessary during the formation of Ag NPs and the PTA complex can be fabricated much more rapidly. As a result, the magnetic composite can be synthesized simply with less cost. Moreover, the composite has a high magnetic saturation value of 55.47emug-1 owing to the Fe3O4 core and the magnetic separation ability can play an important role in the recovery of the disinfectant.

Corrosion effect of Bacillus cereus on X80 pipeline steel in a Beijing soil environment.

The corrosion of X80 pipeline steel in the presence of Bacillus cereus (B. cereus) was studied through electrochemical and surface analyses and live/dead staining. Scanning electron microscopy and live/dead straining results showed that a number of B. cereus adhered to the X80 steel. Electrochemical impedance spectroscopy showed that B. cereus could accelerate the corrosion of X80 steel. In addition, surface morphology observations indicated that B. cereus could accelerate pitting corrosion in X80 steel. The depth of the largest pits due to B. cereus was approximately 11.23µm. Many pits were found on the U-shaped bents and cracks formed under stress after 60days of immersion in the presence of B. cereus. These indicate that pitting corrosion can be accelerated by B. cereus. X-ray photoelectron spectroscopy results revealed that NH4+ existed on the surface of X80 steel. B. cereus is a type of nitrate-reducing bacteria and hence the corrosion mechanism of B. cereus may involve nitrate reduction on the X80 steel.

Enhanced silver loaded antibacterial titanium implant coating with novel hierarchical effect.

In this study, we present a novel strategy for hierarchical antibacterial implant coating by controlling structural and componential features as regulators of surface bactericidal property. Anodized titanium dioxide nanotubes and self-polymerized polydopamine were both used as preliminary antibacterial agents with a significant positive effect on surface bioactivity. At the same time, the storage capacity of nanotubes and the in situ reduction activity of polydopamine can introduce large amounts of strong attached silver nanoparticles for enhanced stable antibacterial performance. The surface morphology, chemical composition, and hydrophilicity had been thoroughly characterized. The sustained silver release performances were continuously monitored. The successively in vitro inhibition on Staphylococcus aureus growth of titanium dioxide nanotube, polydopamine layer and silver nanoparticles demonstrated the hierarchical antibacterial property of the final silver nanoparticles-incorporated polydopamine-modified titanium dioxide nanotube coating (silver/polydopamine/nanotube). Moreover, the bioactivity investigation indicated the vital role of polydopamine-modified titanium dioxide nanotube coating on preserving healthy osteoblast activity at the implant interface. The unique hierarchical coating for titanium implant may be a promising method to maximize antibacterial capacity and maintain good cellular activity at the same time.

Alkalescent nanotube films on a titanium-based implant: A novel approach to enhance biocompatibility.

The interfacial pH value has a marked effect on cell viability because the pro-mineralization activity of osteoblasts increases at alkaline extracellular pH, whereas the pro-resorptive activity of osteoclasts increases under more acidic conditions. To obtain the more favorable alkaline interface, we developed a novel nanotube layer that was incorporated with magnesium oxide on a titanium implant substrate (MgO/NT/Ti) via ethylenediamine tetraacetic acid (EDTA) chelation. This facile immersion-annealing process successfully created a homogeneous magnesium oxide layer with sustained release kinetics and superior hydrophilicity according to the surface characterization and microenvironment measurement. The titania nanotubes on the substrate with an anatase phase exhibited a lower passivation current and a more positive corrosion potential compared with pure titanium, which guaranteed a reasonable corrosion resistance, even when it was wrapped with a magnesium oxide layer. In vitro cell cultures showed that MgO/NT/Ti significantly increased cell proliferation and alkaline phosphatase (ALP) activity. The resulting alkalescent microenvironment created by the MgO layer encouraged the cells to spread into polygonal shapes, accelerated the differentiation stage to osteoblast and induced a higher expression of vinculin. In summary, the incorporated alkalescent microenvironment of MgO/NT/Ti provided a viable approach to stimulate cell proliferation, adhesion, and differentiation and to improve the implant osseointegration.

Accelerated corrosion of 2205 duplex stainless steel caused by marine aerobic Pseudomonas aeruginosa biofilm.

Microbiologically influenced corrosion (MIC) of 2205 duplex stainless steel (DSS) in the presence of Pseudomonas aeruginosa was investigated through electrochemical and surface analyses. The electrochemical results showed that P. aeruginosa significantly reduced the corrosion resistance of 2205 DSS. Confocal laser scanning microscopy (CLSM) images showed that the depths of the largest pits on 2205 DSS with and without P. aeruginosa were 14.0 and 4.9µm, respectively, indicating that the pitting corrosion was accelerated by P. aeruginosa. X-ray photoelectron spectroscopy (XPS) results revealed that CrO3 and CrN formed on the 2205 DSS surface in the presence of P. aeruginosa.

Microbiologically Influenced Corrosion of 2707 Hyper-Duplex Stainless Steel by Marine Pseudomonas aeruginosa Biofilm.

Microbiologically Influenced Corrosion (MIC) is a serious problem in many industries because it causes huge economic losses. Due to its excellent resistance to chemical corrosion, 2707 hyper duplex stainless steel (2707 HDSS) has been used in the marine environment. However, its resistance to MIC was not experimentally proven. In this study, the MIC behavior of 2707 HDSS caused by the marine aerobe Pseudomonas aeruginosa was investigated. Electrochemical analyses demonstrated a positive shift in the corrosion potential and an increase in the corrosion current density in the presence of the P. aeruginosa biofilm in the 2216E medium. X-ray photoelectron spectroscopy (XPS) analysis results showed a decrease in Cr content on the coupon surface beneath the biofilm. The pit imaging analysis showed that the P. aeruginosa biofilm caused a largest pit depth of 0.69 µm in 14 days of incubation. Although this was quite small, it indicated that 2707 HDSS was not completely immune to MIC by the P. aeruginosa biofilm.