Cancer-Thylakoid Hybrid Membrane Camouflaged Thulium Oxide Nanoparticles with Oxygen Self-Supply Capability for Tumor-Homing Phototherapy.

Nanomaterials that generate reactive oxygen species (ROS) upon light irradiation have significant applications in various fields, including photodynamic therapy (PDT) that is widely recognized as a highly momentous strategy for the eradication of cancer cells. However, the ROS production rate of photosensitizers, as well as the tumor hypoxia environment, are two major challenges that restrict the widespread application of PDT. In this study, a cancer-thylakoid hybrid membrane-camouflaged thulium oxide nanoparticles (Tm2O3) for tumor-homing phototherapy through dual-stage-light-guided ROS generation and oxygen self-supply is developed. Tm2O3 as a type II photosensitizer are viable for NIR-stimulated ROS generation due to the unique energy levels, large absorption cross section, and long lifetime of the 3H4 state of Tm ions. The thylakoid membrane (TK) plays a catalase-like role in converting hydrogen peroxide into oxygen and also acts as a natural photosensitizer that can generate lethal ROS through electron transfer when exposed to light. In addition, fluorescence dye DiR is embedded in the hybrid membrane for in vivo tracing as well as photothermal therapy. Results show that tumors in Tm2O3@TK-M/DiR group are effectively ablated following dual-stage-light irradiation, highlighting the promising potential of rare-earth element-based type II photosensitizers in various applications.

Resilient and sustainable production of peanut (Arachis hypogaea) in phosphorus-limited environment by using exogenous gamma-aminobutyric acid to sustain photosynthesis.

Globally, many low to medium yielding peanut fields have the potential for further yield improvement. Low phosphorus (P) limitation is one of the significant factors curtailing Arachis hypogaea productivity in many regions. In order to demonstrate the effects of gamma-aminobutyric acid (GABA) on peanuts growing under P deficiency, we used a pot-based experiment to examine the effects of exogenous GABA on alleviating P deficiency-induced physiological changes and growth inhibition in peanuts. The key physiological parameters examined were foliar gas exchange, photochemical efficiency, proton motive force, reactive oxygen species (ROS), and adenosine triphosphate (ATP) synthase activity of peanuts under cultivation with low P (LP, 0.5 mM P) and control conditions. During low P, the cyclic electron flow (CEF) maintained the high proton gradient (∆pH) induced by low ATP synthetic activity. Applying GABA during low P conditions stimulated CEF and reduced the concomitant ROS generation and thereby protecting the foliar photosystem II (PSII) from photoinhibition. Specifically, GABA enhanced the rate of electronic transmission of PSII (ETRII) by pausing the photoprotection mechanisms including non-photochemical quenching (NPQ) and ∆pH regulation. Thus, GABA was shown to be effective in restoring peanut growth when encountering P deficiency. Exogenous GABA alleviated two symptoms (increased root-shoot ratio and photoinhibition) of P-deficient peanuts. This is possibly the first report of using exogenous GABA to restore photosynthesis and growth under low P availability. Therefore, foliar applications of GABA could be a simple, safe and effective approach to overcome low yield imposed by limited P resources (low P in soils or P-fertilizers are unavailable) for sustainable peanut cultivation and especially in low to medium yielding fields.

High-Light-Induced Degradation of Photosystem II Subunits' Involvement in the Albino Phenotype in Tea Plants.

The light-sensitive (LS) albino tea plant grows albinic shoots lacking chlorophylls (Chls) under high-light (HL) conditions, and the albinic shoots re-green under low light (LL) conditions. The albinic shoots contain a high level of amino acids and are preferential materials for processing quality green tea. The young plants of the albino tea cultivars are difficult to be cultivated owing to lacking Chls. The mechanisms of the tea leaf bleaching and re-greening are unknown. We detected the activity and composition of photosystem II (PSII) subunits in LS albino tea cultivar "Huangjinya" (HJY), with a normal green-leaf cultivar "Jinxuan" (JX) as control so as to find the relationship of PSII impairment to the albino phenotype in tea. The PSII of HJY is more vulnerable to HL-stress than JX. HL-induced degradation of PSII subunits CP43, CP47, PsbP, PsbR. and light-harvest chlorophyll-protein complexes led to the exposure and degradation of D1 and D2, in which partial fragments of the degraded subunits were crosslinked to form larger aggregates. Two copies of subunits PsbO, psbN, and Lhcb1 were expressed in response to HL stress. The cDNA sequencing of CP43 shows that there is no difference in sequences of PsbC cDNA and putative amino acids of CP43 between HJY and JX. The de novo synthesis and/or repair of PSII subunits is considered to be involved in the impairment of PSII complexes, and the latter played a predominant role in the albino phenotype in the LS albino tea plant.

Iron Supplement-Enhanced Growth and Development of Hydrangea macrophylla In Vitro under Normal and High pH.

Hydrangea macrophylla is a popular perennial ornamental shrub commercially grown as potted plants, landscape plants, and cut flowers. In the process of reproduction and production of ornamental plants, the absorption of nutrients directly determines the value of the ornamental plants. Hydrangea macrophylla is very sensitive to the content and absorption of the micronutrient iron (Fe) that affects growth of its shoots. However, the physiological activity of Fe as affected by deficiency or supplementation is unknown. This work aimed at preliminary exploring the relationship between Fe and photosynthesis, and also to find the most favorable iron source and level of pH for the growth of H. macrophylla. Two Fe sources, non-chelated iron sulfate (FeSO4) and iron ethylenediaminetetraacetic acid (Fe-EDTA), were supplemented to the multipurpose medium with a final Fe concentration of 2.78 mg·L-1. The medium without any Fe supplementation was used as the control. The pH of the agar-solidified medium was adjusted to either 4.70, 5.70, or 6.70, before autoclaving. The experiment was conducted in a culture room for 60 days with 25/18 °C day and night temperatures, and a 16-hour photoperiod provided at a light intensity of 50 mmol·m-2·s-1 photosynthetic photon flux density (PPFD) from white light-emitting diodes. Supplementary Fe increased the tissue Fe content, and leaves were greener with the medium pH of 4.70, regardless of the Fe source. Compared to the control, the number of leaves for plantlets treated with FeSO4 and Fe-EDTA were 2.0 and 1.5 times greater, respectively. The chlorophyll, macronutrient, and micronutrient contents were the greatest with Fe-EDTA at pH 4.70. Furthermore, the Fe in the leaf affected the photosynthesis by regulating stomata development, pigment content, and antioxidant system, and also by adjusting the expression of genes related to Fe absorption, transport, and redistribution. Supplementation of Fe in a form chelated with EDTA along with a medium pH of 4.70 was found to be the best for the growth and development of H. macrophylla plantlets cultured in vitro.

Changes of body composition and circulating neopterin, omentin-1, and chemerin in response to thylakoid-rich spinach extract with a hypocaloric diet in obese women with polycystic ovary syndrome: A randomized controlled trial.

This trial evaluated the effects of thylakoid-rich spinach extract supplementation combined with a hypocaloric diet on body composition and serum levels of neopterin, chemerin, and omentin-1 in obese women with polycystic ovary syndrome (PCOS). In this randomized controlled trial, 48 obese women with PCOS, aged 20-45 years old, were recruited and randomly divided into thylakoid (n = 24) and placebo (n = 24) groups. They received a low-calorie diet with 5 g/day thylakoid-rich spinach extract or a low-calorie diet with 5 g/day placebo for 12 weeks. The mean age of the participants of the thylakoid group was 31.86 years, and the placebo group was 32.04 years. Thylakoid-rich spinach extract supplementation with a low-calorie diet increased serum levels of omentin-1 (10.90 vs. 3.87 ng/L; p < .001) and decreased fat mass (-5.19 vs. -1.35 kg; p < .001) and serum levels of neopterin (-0.66 vs. -0.38 nmol/L; p = .003) and chemerin (-41.24 vs. -11.26 ng/L; p < .001) in the thylakoid group compared to the placebo group. A significant improvement in omentin-1, chemerin, and neopterin by thylakoid-rich spinach extract supplementation was under the influence of weight change and insulin resistance status throughout the study. A significant decrease in the other anthropometric indices and insulin resistance was also observed in the thylakoid group, compared to the placebo group (p < .001, for all parameters). Thylakoid-rich spinach extract combined with a low-calorie diet increased circulating omentin-1 and decreased fat mass, abdominal obesity, as well as circulating chemerin, neopterin, and insulin in obese women with PCOS.

The effects of spinach-derived thylakoid supplementation in combination with calorie restriction on anthropometric parameters and metabolic profiles in obese women with polycystic ovary syndrome: a randomized, double-blind, placebo-controlled clinical trial.

BACKGROUND: There is a promising outlook regarding the potential effect of spinach-derived thylakoids in the management of obesity and its associated metabolic disturbances. This research aimed to evaluate the effects of spinach-derived thylakoids supplementation combined with a calorie-restricted diet on anthropometric and metabolic profiles in obese women with the polycystic ovary syndrome (PCOS). METHODS: In a 12-week double-blind placebo-controlled randomized clinical trial, 48 females with obesity and PCOS were randomly allocated into either intervention (5 g/day thylakoid) or placebo (5 g/day cornstarch) groups along with calorie-restricted diets. Anthropometric measures, physical activity levels, dietary intakes, insulin resistance markers, as well as serum levels of insulin, fasting blood glucose (FBG), non-esterified fatty acids (NEFA), and sex hormones including dehydroepiandrosterone sulfate (DHEAS), follicle-stimulating hormone (FSH), luteinizing hormone (LH), sex hormone-binding globulin (SHBG), and free androgen index (FAI) were evaluated pre-and post-intervention. RESULTS: After the 12-week intervention, there were significant decreases in weight (- 6.97 ± 0.52 vs. -3.19 ± 0.72 kg; P < 0.001), waist circumference (- 7.78 ± 2.50 vs. -3.73 ± 1.40 cm; P < 0.001), fat mass (- 5.19 ± 0.53 vs. -1.36 ± 0.39 kg; P < 0.001), and insulin levels (- 5.40 ± 1.86 vs. -1.19 ± 0.85 µU/mL; P < 0.001) in the spinach-derived thylakoid group compared to the placebo group. Furthermore, insulin resistance markers and serum levels of testosterone decreased significantly in the thylakoid group compared to the placebo group (P < 0.05). The changes in other parameters did not show significant differences between the two groups. CONCLUSIONS: Spinach-derived thylakoid supplementation resulted in more favorable improvements in anthropometric indices and insulin sensitivity compared to the calorie restriction alone. TRIAL REGISTRATION: The study was approved by the Ethics Committee of Research Vice-chancellor of Tabriz University of Medical Sciences, Tabriz, Iran, and was registered in the Iranian Registry of Clinical Trials (registration ID: IRCT20140907019082N9 ).

The effects of hydroalcoholic extract of spinach on prevention and treatment of some metabolic and histologic features in a rat model of nonalcoholic fatty liver disease.

BACKGROUND: This study evaluated the effects of hydroalcoholic extract of spinach (HES) on nonalcoholic fatty liver disease (NAFLD). In the prevention phase, 18 Sprague-Dawley rats were fed a high-fat diet, a high-fat diet plus 400 mg kg-1 HES, or a chow diet for 7 weeks. For the treatment phase, after the induction of NAFLD, they were fed a high-fat diet, a high-fat diet plus 400 mg kg-1 HES, a chow diet, or chow diet plus 400 mg kg-1 HES for 4 weeks (n = 6). RESULTS: Weight gain (P = 0.01), food intake (P < 0.01), serum glucose (P = 0.01), triglyceride (TG) (P = 0.02), low-density lipoprotein cholesterol (LDL-c) (P = 0.01), aspartate aminotransferase (AST) (P = 0.02), liver steatosis, and the nonalcoholic fatty liver disease (NAFLD) activity score (NAS) (P < 0.01) in the high-fat group were statistically higher than in the other groups at the end of the prevention phase. Feeding spinach extract to rats on a high-fat diet decreased serum glucose (P = 0.01), total cholesterol (TCh) (P < 0.01), AST (P = 0.01), alkaline phosphatase (ALP) (P < 0.01), and liver steatosis (P < 0.01) in the treatment phase. CONCLUSION: Overall, spinach extract showed beneficial effects in the prevention and treatment of NAFLD. © 2019 Society of Chemical Industry.

Chloroplast ultrastructure in plants.

The chloroplast organelle in mesophyll cells of higher plants represents a sunlight-driven metabolic factory that eventually fuels life on our planet. Knowledge of the ultrastructure and the dynamics of this unique organelle is essential to understanding its function in an ever-changing and challenging environment. Recent technological developments promise unprecedented insights into chloroplast architecture and its functionality. The review highlights these new methodical approaches and provides structural models based on recent findings about the plasticity of the thylakoid membrane system in response to different light regimes. Furthermore, the potential role of the lipid droplets plastoglobuli is discussed. It is emphasized that detailed structural insights are necessary on different levels ranging from molecules to entire membrane systems for a holistic understanding of chloroplast function.

Effects of Thylakoid-Rich Spinach Extract on the Pharmacokinetics of Drugs in Rats.

Thylakoid-rich spinach extract is being used as dietary weight-loss supplements in Japan. A recent rat study has suggested that intake of thylakoid-rich spinach extract with dietary oil inhibits dietary fat absorption via binding to bile acids, which promotes excretion of bile acids in feces. While, we confirmed that a serving size of thylakoid-rich spinach extract contains a large amount of calcium (130 mg/5 g). Therefore, using rats, we evaluated whether one-time ingestion of thylakoid-rich spinach extract affects the gastrointestinal absorption of water-insoluble drugs, such as griseofulvin (GF) and indomethacin (IM), or ciprofloxacin (CPFX) that chelate with polyvalent metal cations. Pretreatment of the rats with thylakoid-rich spinach extract (100 or 300 mg/kg) for 15 min prior to oral administration of GF (50 mg/kg) or IM (10 mg/kg) did not significantly alter the pharmacokinetic properties of either drug. Meanwhile, co-administration of thylakoid-rich spinach extract (500 mg/kg) and CPFX (20 mg/kg) significantly reduced the peak plasma concentration and the area under the plasma concentration-time curve of CPFX to 25 and 40%, respectively in rats. In vitro studies demonstrated that when a mixture of thylakoid-rich spinach extract and CPFX was centrifuged, there was a significant reduction in the supernatant concentration of CPFX relative to the control. When the experiment was repeated in the presence of ethylenediaminetetraacetic acid, the concentration of CPFX was unchanged. These results suggest that the intake of thylakoid-rich spinach extract may reduce the absorption of drugs that form a chelate with polyvalent metal cations, such as CPFX.

Thylakoid proteome modulation in pea plants grown at different irradiances: quantitative proteomic profiling in a non-model organism aided by transcriptomic data integration.

Plant thylakoid membranes contain hundreds of proteins that closely interact to cope with ever-changing environmental conditions. We investigated how Pisum sativum L. (pea) grown at different irradiances optimizes light-use efficiency through the differential accumulation of thylakoid proteins. Thylakoid membranes from plants grown under low (LL), moderate (ML) and high (HL) light intensity were characterized by combining chlorophyll fluorescence measurements with quantitative label-free proteomic analysis. Protein sequences retrieved from available transcriptomic data considerably improved thylakoid proteome profiling, increasing the quantifiable proteins from 63 to 194. The experimental approach used also demonstrates that this integrative omics strategy is powerful for unravelling protein isoforms and functions that are still unknown in non-model organisms. We found that the different growth irradiances affect the electron transport kinetics but not the relative abundance of photosystems (PS) I and II. Two acclimation strategies were evident. The behaviour of plants acclimated to LL was compared at higher irradiances: (i) in ML, plants turn on photoprotective responses mostly modulating the PSII light-harvesting capacity, either accumulating Lhcb4.3 or favouring the xanthophyll cycle; (ii) in HL, plants reduce the pool of light-harvesting complex II and enhance the PSII repair cycle. When growing at ML and HL, plants accumulate ATP synthase, boosting both cyclic and linear electron transport by finely tuning the ΔpH across the membrane and optimizing protein trafficking by adjusting the thylakoid architecture. Our results provide a quantitative snapshot of how plants coordinate light harvesting, electron transport and protein synthesis by adjusting the thylakoid membrane proteome in a light-dependent manner.

Normalizing Tumor Microenvironment Based on Photosynthetic Abiotic/Biotic Nanoparticles.

Tumor hypoxia has attained the status of a core hallmark of cancer that globally affects the entire tumor phenotype. Reversing tumor hypoxia might offer alternative therapeutic opportunities for current anticancer therapies. In this research, a photosynthetic leaf-inspired abiotic/biotic nano-thylakoid (PLANT) system was designed by fusing the thylakoid membrane with synthetic nanoparticles for efficient O2 generation in vivo. Under 660 nm laser irradiation, the PLANT system exhibited intracellular O2 generation and the anaerobic respiration of the multicellular tumor spheroid was suppressed by PLANT as well. In vivo, it was found that PLANT could not only normalize the entire metabolic network but also adjust the abnormal structure and function of the tumor vasculature. It was demonstrated that PLANT could significantly enhance the efficacy of phototherapy or antiangiogenesis therapy. This facile approach for normalizing the tumor microenvironment will find great potential in tumor therapy.

Dynamic remobilization of leaf nitrogen components in relation to photosynthetic rate during grain filling in maize.

Remobilization of leaf nitrogen (N) contributes greatly to grain N in maize, but leads to low photosynthetic rate (Pn). Pn is determined by various N components involving in light harvest and CO2 reduction. However, it is less clear which N component is the major contributor for the reduction of photosynthesis in modern stay-green maize hybrids. In this study, we analyzed the relationship between remobilization of different N components and Pn during grain filling stage under low N (no N application) and high N (180 kg N ha-1) in a field experiment. The remobilization efficiency of photosynthetic enzymes (PEPc, PPDK and Rubisco) in the leaf was much higher than that of thylakoid N and other N components. Low N supply increased the remobilization efficiency of all the leaf N components. During grain filling stage, the amount of all the N components decreased together with Pn. The ratio of Pn to the N in the PEPc, PPDK and Rubisco kept increase in the whole grain filling stage, while the ratio of Pn to chlorophyll and thylakoid-N decreased. Correlation analysis indicated that Pn was more related to the content of photosynthetic enzymes than to chlorophyll and thylakoid N. It is concluded that photosynthetic enzymes serve as an N storage reservoir at early grain filling stage and their degradation is critical in the reduction of Pn during later grain filling stage. Future breeding targets may be focused on enhancing the efficiency of photosynthetic enzymes during late grain filling stage.

An optimized protocol for the preparation of oxygen-evolving thylakoid membranes from Cyclotella meneghiniana provides a tool for the investigation of diatom plastidic electron transport.

BACKGROUND: The preparation of functional thylakoid membranes from diatoms with a silica cell wall is still a largely unsolved challenge. Therefore, an optimized protocol for the isolation of oxygen evolving thylakoid membranes of the centric diatom Cyclotella meneghiniana has been developed. The buffer used for the disruption of the cells was supplemented with polyethylene glycol based on its stabilizing effect on plastidic membranes. Disruption of the silica cell walls was performed in a French Pressure cell and subsequent linear sorbitol density gradient centrifugation was used to isolate the thylakoid membrane fraction. RESULTS: Spectroscopic characterization of the thylakoids by absorption and 77 K fluorescence spectroscopy showed that the photosynthetic pigment protein complexes in the isolated thylakoid membranes were intact. This was supported by oxygen evolution measurements which demonstrated high electron transport rates in the presence of the artificial electron acceptor DCQB. High photosynthetic activity of photosystem II was corroborated by the results of fast fluorescence induction measurements. In addition to PSII and linear electron transport, indications for a chlororespiratory electron transport were observed in the isolated thylakoid membranes. Photosynthetic electron transport also resulted in the establishment of a proton gradient as evidenced by the quenching of 9-amino-acridine fluorescence. Because of their ability to build-up a light-driven proton gradient, de-epoxidation of diadinoxanthin to diatoxanthin and diatoxanthin-dependent non-photochemical quenching of chlorophyll fluorescence could be observed for the first time in isolated thylakoid membranes of diatoms. However, the ∆pH, diadinoxanthin de-epoxidation and diatoxanthin-dependent NPQ were weak compared to intact diatom cells or isolated thylakoids of higher plants. CONCLUSIONS: The present protocol resulted in thylakoids with a high electron transport capacity. These thylakoids can thus be used for experiments addressing various aspects of the photosynthetic electron transport by, e.g., employing artificial electron donors and acceptors which do not penetrate the diatom cell wall. In addition, the present isolation protocol yields diatom thylakoids with the potential for xanthophyll cycle and non-photochemical quenching measurements. However, the preparation has to be further refined before these important topics can be addressed systematically.