Hydroxyethyl starch conjugates co-assembled nanoparticles promote photodynamic therapy and antitumor immunity by inhibiting antioxidant systems

Photodynamic therapy(PDT)can produce high levels of reactive oxygen species(ROS)to kill tumor cells and induce antitumor immunity.However,intracellular antioxidant systems,including glutathione(GSH)system and thioredoxin(Trx)system,limit the accumulation of ROS,resulting in compromised PDT and insufficient immune stimulation.Herein,we designed a nanomedicine PtHPs co-loading photosensitizer pyropheophorbide a(PPa)and cisplatin prodrug Pt-COOH(Ⅳ)(Pt(Ⅳ))based on hydroxyethyl starch(HES)to inhibit both GSH and Trx antioxidant systems and achieve potent PDT as well as antitumor immune responses.Specifically,HES-PPa and HES-Pt were obtained by coupling HES with PPa and Pt(Ⅳ),and assembled into nanoparticle PtHPs by emulsification method to achieve the purpose of co-delivery of PPa and Pt(Ⅳ).PtHPs improved PPa photostability while retaining PPa photodynamic properties.In vitro experiments showed that PtHPs reduced GSH,inhibited Trx system and had better cell-killing effect and ROS generation ability.Subcutaneous tumormodels showed that PtHPs had good safety and tumor inhibition effect.Bilateral tumor models suggested that PtHPs promoted the release of damage-associated molecular patterns and the maturation of dendritic cells,induced T cell-mediated immune responses,and thus suppressed the growth of both primary and distal tumors.This study reports a novel platinum-based nanomedicine and provides a newstrategy for boosting PDT therapy-mediated antitumor immunity by overcoming intrinsic antioxidant systems.

The Relative Contribution of Non-Foliar Organs of Cotton to Yield and Related Physiological Characteristics Under Water Defi cit

Water deficit is one of the most important causes of decreased yield in cultivated plants. Non-foliar green organs in cotton play an important role in yield formation at the late growth stage. Although better photosynthetic performance was observed in a non-foliar organ （bract） compared with leaves under water deficit. However, the physiological response of each organ in cotton to water deficit has not been comprehensively studied in relation to the water status and photosynthesis characteristics. We studied the maintenance of water status of each organ in cotton by measuring their relative water content, proline content and stomatal characteristics. Water deficit significantly decreased the surface area of each organ, but to a lesser extent in non-foliar organs. Our results showed that the relative contribution of biomass accumulation of non-foliar organs increased under water deficit. Non-foliar organs （bracts and capsule wall） showed less ontogenetic decrease in O2 evolution capacity and in RuBPC activity （per dry weight） as well as better antioxidant systems than leaves at various days after anthesis. We conclude that the photosynthesis from non-foliar organs is important for increasing cotton yield especially under water deficit conditions.

Rejuvenating soybean(Glycine max L.)growth and development through slight shading stress

The impact of increased shading stress on agronomic traits,photosynthetic performance and antioxidants activities in leaves of two soybeans cultivars(D16 and E93)was studied.Soybean seedlings were grown in pots and exposed to no shade(S0),slight shade(S1),moderate shade(S2),and heavy shade(S3).Our findings showed that under the S3 in both cultivars,leaf fresh weight(LFW),specific leaf area(SLA)and leaf thickness decreased signifiantly,accompanied by a reduction in photochemical parameters including the maximum quantum yield(Fv/Fm)and electron transport rate(ETR).Furthermore,compared to SO,S1 significantly increased the ETR,sucrose content and the activity of catalase(CAT)in both D16 and E93 cultivars while S2 and S3 decreased the activity.However,under all treatments of shading stress,the antioxidant activities of superoxide dismutase(SOD)and peroxidase(POD)were lowered in both cultivars.Such morphological and physiological plasticity to adapt S1 compensates for the decrease in biomass and leads to seed weight compared to that obtained with an amount of normal light.Through configuring the space in the intercropping systems,S1 could be helpful for optimum growth and yield.Redesigning photosynthesis through S1 for the intercropping systems could be a smart approach.

Comprehensive comparison of water quality risk and microbial ecology between new and old cast iron pipe distribution systems

The effects of cast iron pipe corrosion onwater quality risk and microbial ecology in drinking water distribution systems(DWDSs)were investigated.It was found that trihalomethane(THMs)concentration and antibiotic resistance genes(ARGs)increased sharply in the old DWDSs.Under the same residual chlorine concentration conditions,the adenosine triphos-phate concentration in the effluent of old DWDSs(Eff-old)was significantly higher than that in the effluent of newDWDSs.Moreover,stronger bioflocculation ability andweaker hy-drophobicity coexisted in the extracellular polymeric substances of Eff-old,meanwhile,iron particles could be well inserted into the structure of the biofilms to enhance the mechanical strength and stability of the biofilms,hence enhancing the formation of THMs.Old DWDSs significantly influenced the microbial community of bulk water and triggered stronger mi-crobial antioxidant systems response,resulting in higher ARGs abundance.Corroded cast iron pipes induced a unique interaction system of biofilms,chlorine,and corrosion prod-ucts.Therefore,as the age of cast iron pipes increases,the fluctuation of water quality and microbial ecology should be paid more attention to maintain the safety of tap water.

UV-B Radiation Suppresses the Growth and Antioxidant Systems of Two Marine Microalgae, Platymonas subcordiformis （Wille） Hazen and Nitzschia closterium （Ehrenb.） W. Sm

Abstract: This study investigated whether increased solar UV-B radiation (280–315 nm) could suppress the growth of marine microalgae through effects on their antioxidant systems. Two marine microalgae species, Platymonas subcordiformis (Wille) Hazen and Nitzschia closterium(Ehrenb.) W. Sm, were exposed to a range of UV-B radiation and both showed reductions in their growth rates, and the chlorophyll a (Chl a) and carotenoid (Car) contents when UV-B radiation dose increased. Superoxide anion radical (O2-.) production and the concentration of hydrogen peroxide (H2O2) and malodiadehyde (MDA) also increased with the increasing of UV-B radiation. Antioxidant systems, non-enzymic components (Car and glutathione content) and enzymic components (superoxide dismutase (SOD) and catalase (CAT) activity), decreased as a result of enhanced UV-B radiation. When the exogenous glutathione (GSH) was added, the effects of UV-B radiation on the growth of the two species were alleviated. These results suggest that enhanced UV-B radiation suppressed the antioxidant systems and caused some active oxygen species to accumulate, which in turns retarded the development of the marine microalgae.