Succinate Dehydrogenase Activity Research Articles

Antibacterial activity and mechanism of ginger extract against Ralstonia solanacearum.

The current study aimed to determine the chemical compositions of ginger extract (GE) and to assess the antibacterial activities of GE against the ginger bacterial wilt pathogen Ralstonia solanacearum and to screen their mechanisms of action. A total of 393 compounds were identified by using ultra-performance liquid chromatography and tandem-mass spectrometry. The antibacterial test indicated that GE had strong antibacterial activity against R. solanacearum and that the bactericidal effect exhibited a dose-dependent manner. The minimum inhibitory concentration and minimum bactericidal concentration of R. solanacearum were 3.91 and 125 mg/ml, respectively. The cell membrane permeability and integrity of R. solanacearum were destroyed by GE, resulting in cell content leakage, such as electrolytes, nucleic acids, proteins, extracellular adenosine triphosphate and exopoly saccharides. In addition, the activity of cellular succinate dehydrogenase and alkaline phosphatase of R. solanacearum decreased gradually with an increase in the GE concentration. Scanning electron microscopy analysis revealed that GE treatment changed the morphology of the R. solanacearum cells. Further experiments demonstrated that GE delayed or slowed the occurrence of bacterial wilt on ginger. GE has a significant antibacterial effect on R. solanacearum, and the antibacterial effect is concentration dependent. The GE treatments changed the morphology, destroyed membrane permeability and integrity, reduced key enzyme activity and inhibit the synthesis of the virulence factor EPS of R. solanacearum. GE significantly controlled the bacterial wilt of ginger during infection. This research provides insight into the antimicrobial mechanism of GE against R. solanacearum, which will open a new application field for GE.

Dietary thiamine modulates carbohydrate metabolism, antioxidant status, and alleviates hypoxia stress in oriental river prawn Macrobrachium nipponense (de Haan)

Hypoxia is one of the challenges in prawns aquaculture. However, the role of thiamine, which is a coenzyme in carbohydrate metabolism with antioxidant properties, in reducing hypoxia in prawns aquaculture is currently unknown. We investigated the effects of thiamine on antioxidant status, carbohydrate metabolism and acute hypoxia in oriental river prawn, Macrobrachium nipponense. One thousand eight hundred prawns (0.123 ± 0.003 g) were fed five diets (60 prawns each tank, six replicates per diet) supplemented with graded thiamine levels (5.69, 70.70, 133.67, 268.33 and 532.00 mg/kg dry mater) for eight weeks and then exposed to hypoxia stress for 12 h followed by reoxyegnation for 12 h. The results showed that, under normoxia, prawns fed the 133.67 or 268.33 mg/kg thiamine diet had significantly lower glucose 6-phosphatedehydrogenase, succinate dehydrogenase and phosphoenolpyruvate carboxykinase activities than those fed the other diets. Moreover, total antioxidant capacity (T-AOC) increased significantly when prawns were fed the 133.67 mg/kg thiamine diet. Superoxide dismutase (SOD) activity and malonaldehyde (MDA) content also increased significantly when prawns were fed the 268.33 or 532.00 mg/kg thiamine diet under hypoxia. And the significantly increased SOD activity and MDA level also observed in prawns fed 532.00 mg/kg thiamine under reoxygenation. Under normoxia, prawns fed the 70.70 or 133.67 mg/kg thiamine diet decreased the mRNA expressions of AMP-activated protein kinase-alpha (AMPK-α), pyruvate dehydrogenase-E1-α subunit (PDH-E1-α) and hypoxia-inducible factor-1s (HIF-1α, HIF-1β), but increased the mRNA expressions of phosphofructokinase (PFK) significantly. After 12 h of hypoxia, the energy metabolism related genes (AMPK-β, AMPK-γ, PFK, PDH-E1-α), hypoxia-inducible factor related genes (HIF-1α, HIF-1β) and thiamine transporter gene (SLC19A2) were up-regulated significantly in prawns fed the 133.67 or 268.33 mg/kg thiamine diets. After 12 h of reoxygenation, prawns fed the 133.67 or 268.33 mg/kg diet significantly decreased the SOD activity, MDA level and SLC19A2 mRNA expression compared with other diets. The optimum thiamine was 161.20 mg/kg for minimum MDA content and 143.17 mg/kg for maximum T-AOC activity based on cubic regression analysis. In summary, supplementing 143.17 to 161.20 mg/kg thiamine in the diets for M. nipponense improves the antioxidant capacity under normoxia and reduces the oxidative damage under hypoxia stress.

In vitro toxicological prospection of fungicides containing Difenoconazole or Tebuconazole as active ingredients

The active ingredients (AI) tebuconazole and difenoconazole (classified as toxic to living organisms and potentially mutagen, carcinogen, or teratogen) are part of the composition of widely used fungicides in crops. In 2016 they were found in irregular quantities by ANVISA in their latest report emitted by the Program of Analysis of Agrochemical Waste in Food. Two commercial fungicides containing the active ingredients tebuconazole and difenoconazole were evaluated in cytogenotoxic assays and on different biological molecules. Both active ingredients altered the clotting time of the plasma, and were procoagulants in the majority of the evaluated doses. The two AI acted on blood thrombi exerting thrombotic action and confirming the observed procoagulant potential. In the proteolysis assay, the AI did not alter the structure of fibrinogen under the conditions evaluated. Tebuconazole and Difenoconazole were also cytotoxic to human erythrocytes, as well as induced phospholipid breakdown, confirming their toxicity on membranes. However, under the conditions evaluated, the AI did not alter significantly the mitochondrial succinate dehydrogenase activity and did not induce DNA fragmentation. Assuming that changes in human cells and molecules have a cumulative effect, the toxic potential of fungicides might be greater when chronic exposure to their active principles occurs.

Effect of the combination of composite skin grafting and recombinant human basic fibroblast growth factor on plastic surgery for extensive sc ars after burns

Purpose: To investigate the effect of combined use of composite skin grafting and recombinant human basic fibroblast growth factor (rh-bFGF) on plastic surgery for extensive burn scars, and its influence on wound healing and inflammatory responses in patients.
 Methods: Hospital records of 120 patients who underwent extensive scar plastic surgery after burns in Hanchuan People’s Hospital from February 2019 to February 2020 were retrospectively analyzed. The patients were equally assigned to study group (STG) and control group (COG), based on the order of admission. All patients received composite skin grafting surgery and post-surgery topical silver sulphadiazine cream regularly, while those in study group (STG) received additional treatment with rh-bFGF spray on the wound surfaces. Scar scores, degree of wound healing, populations of fibrocytes and capillaries, levels of vascular endothelial growth factor (VEGF) and transforming growth factor-β1 (TGF-β1), and activities of lactate dehydrogenase (LDH) and succinate dehydrogenase (SDH) were evaluated.
 Results: Patients in STG had significantly better scar scores, shorter mean wound healing time, higher mean degree of wound healing, higher scores on inflammatory reactions near the wounds, and higher populations of fibrocytes and capillaries, when compared with patients in COG group (p < 0.001). After surgery, there were lower levels of VEGF and TGF-β1, and lower levels of activities of LDH and SDH in STG than in COG group (p < 0.001).
 Conclusion: Rh-bFGF accelerates the proliferation of wound tissue, improves local microcirculation, regulates inflammatory response, and enhances wound healing in burn scar patients when used in combination with composite skin grafting. Therefore, Rh-bFGF has a potential for enhanced management of burn scars.

Effects of 1-MCP Treatment on Physiology and Storage Quality of Root Mustard at Ambient Temperature.

Root mustard is plentiful in vitamins and minerals but shrivels and molds easily. In this study, freshly harvested root mustard was fumigated with various concentrations of 1-Methycyclopropene(1-MCP) (1 µL L−1, 1.5 µL L−1, and 2.0 µL L−1) for 24 h and stored at ambient temperature (17 ± 1 °C) for 35 d. Our data showed that 1-MCP fumigation had a striking preservation effect on maintaining weight loss, fruit firmness, lignin, Vc content, and moisture content, inhibiting respiratory intensity and ethylene release rate, as well as decreasing cell permeability and malondialdehyde (MDA) accumulation and maintaining cell membrane integrity of root mustard. In addition, lipoxygenase (LOX), pyruvate dehydrogenase (PDH), and polyphenol oxidase (PPO) activities were significantly reduced throughout the storage period. In contrast, the activities of succinate dehydrogenase (SDH), superoxide dismutase (SOD), ascorbate peroxidase (APX), phenylalanine deaminase (PAL), and peroxidase (POD) remained at high levels. Results showed that 1-MCP treatments were effective in maintaining the quality of root mustard, and the preservation effect of 1.0 μL·L−1 1-MCP was better than other concentrations of 1-MCP. This study could serve as a theoretical reference for root mustard preservation.

Pathological Features in Paediatric Patients with TK2 Deficiency.

Thymidine kinase (TK2) deficiency causes mitochondrial DNA depletion syndrome. We aimed to report the clinical, biochemical, genetic, histopathological, and ultrastructural features of a cohort of paediatric patients with TK2 deficiency. Mitochondrial DNA was isolated from muscle biopsies to assess depletions and deletions. The TK2 genes were sequenced using Sanger sequencing from genomic DNA. All muscle biopsies presented ragged red fibres (RRFs), and the prevalence was greater in younger ages, along with an increase in succinate dehydrogenase (SDH) activity and cytochrome c oxidase (COX)-negative fibres. An endomysial inflammatory infiltrate was observed in younger patients and was accompanied by an overexpression of major histocompatibility complex type I (MHC I). The immunofluorescence study for complex I and IV showed a greater number of fibres than those that were visualized by COX staining. In the ultrastructural analysis, we found three major types of mitochondrial alterations, consisting of concentrically arranged lamellar cristae, electrodense granules, and intramitochondrial vacuoles. The pathological features in the muscle showed substantial differences in the youngest patients when compared with those that had a later onset of the disease. Additional ultrastructural features are described in the muscle biopsy, such as sarcomeric de-structuration in the youngest patients with a more severe phenotype.

Modulation in carbohydrate and protein metabolism under sublethal concentration of carbosulfan intoxication in the freshwater fish, Cyprinus carpio (L.)

Carbosulfan, a carbamate pesticide extensively employed in rural communities, enters the aquatic environment by the proximity of agricultural lands to water bodies or through direct application in such environments. To know the long-term effect of carbosulfan on carbohydrate and protein metabolism, the fish Cyprinus carpio was exposed to 1/5th sublethal concentration (0.68 mg/L) of 96 h LC50 for 7, 14, and 21 days. Significant (P < 0.05) alterations in the glucose, glycogen, total protein, and free amino acid level, as well as in the activity of enzymes lactate dehydrogenase, succinate dehydrogenase, malate dehydrogenase, protease, aspartate aminotransferase, and alanine aminotransferase were observed in the tissues of C. carpio and the changes developed progressively with exposure time. The significant alternations in carbohydrate metabolic enzymes demonstrate that carbosulfan causes metabolic interference and shifts aerobic metabolism to anaerobiosis in C. carpio, while changes in protein metabolic enzymes explain that carbosulfan may interact with peptide sequences in C. carpio directly or indirectly. Changes in these characteristics may provide an early warning signal for determining carbosulfan toxicity and its impact on aquatic species. As a result, it is necessary to monitor the aquatic system and forecast the hazardous effect of carbosulfan on fish; precautions should be taken while using even low concentrations of carbosulfan, and prohibiting or restricting carbosulfan usage is preferable.

Exposure of zebrafish (Danio rerio) to trans-2-hexenal induces oxidative stress and protein degeneration of the gill

Trans-2-hexenal (T2H) has great commercial value for development as a biopesticide, but its toxicity risk to nontarget organisms is unknown. Here, the toxicity and underlying mechanism of T2H on zebrafish (Danio rerio) were investigated. The LC50 (48 h) of T2H on zebrafish is 4.316 μg/mL, and the aldehyde group is essential to its toxicity. In 14-day chronic toxicity tests, 0.432 μg/mL T2H resulted in a higher mortality of zebrafish than the control group. Furthermore, the sensitivity of zebrafish to different administration methods was gill administration>oral administration>transdermal administration>intravenous injection. T2H induced significant cell death and ROS generation in zebrafish gill cells in a concentration-dependent manner. After treatment with 4.316 μg/mL T2H, the expression of oxidative stress-related genes (nrf2, gstp1, keap1b, sod1 and sod2) and the content of malondialdehyde (MDA) were up-regulated. Incubation with T2H caused an immediate denaturation of gill protein, which was aggravated with increasing dose of T2H. We also found that T2H at 21.225 mg/mL significantly reduced the in vitro activity of succinate dehydrogenase (SDH). Among the three amino acids tested, T2H was only found to react with methionine and glycine to form adducts, which may be the basis of the protein denaturation. This study confirmed that T2H could induce oxidative stress and protein denaturation in zebrafish gills, providing important information for risk assessment of T2H exposure.

Oleamide Reduces Mitochondrial Dysfunction and Toxicity in Rat Cortical Slices Through the Combined Action of Cannabinoid Receptors Activation and Induction of Antioxidant Activity.

The potential treatment of neurodegenerative disorders requires the development of novel pharmacological strategies at the experimental level, such as the endocannabinoid-based therapies. The effects of oleamide (OEA), a fatty acid primary amide with activity on cannabinoid receptors, was tested against mitochondrial toxicity induced by the electron transport chain complex II inhibitor, 3-nitropropionic acid (3-NP), in rat cortical slices. OEA prevented the 3-NP-induced loss of mitochondrial function/cell viability at a concentration range of 5nM-25µM, and this protective effect was observed only when the amide was administered as pretreatment, but not as post-treatment. The preservation of mitochondrial function/cell viability induced by OEA in the toxic model induced by 3-NP was lost when the slices were pre-incubated with the cannabinoid receptor 1 (CB1R) selective inhibitor, AM281, or the cannabinoid receptor 2 (CB2R) selective inhibitor, JTE-907. The 3-NP-induced inhibition of succinate dehydrogenase (mitochondrial Complex II) activity was recovered by 25nM OEA. The amide also prevented the increased lipid peroxidation and the changes in reduced/oxidized glutathione (GSH/GSSG) ratio induced by 3-NP. The cell damage induced by 3-NP, assessed as incorporation of cellular propidium iodide, was mitigated by OEA. Our novel findings suggest that the neuroprotective properties displayed by OEA during the early stages of damage to cortical cells involve the converging activation of CB1R and CB2R and the increase in antioxidant activity, which combined may emerge from the preservation of the functional integrity of mitochondria.

The Impact of Training on the Loss of Cardiorespiratory Fitness in Aging Masters Endurance Athletes.

Elite masters endurance athletes are considered models of optimal healthy aging due to the maintenance of high cardiorespiratory fitness (CRF) until old age. Whereas a drop in VO2max in masters athletes has been broadly investigated, the modifying impact of training still remains a matter of debate. Longitudinal observations in masters endurance athletes demonstrated VO2max declines between −5% and −46% per decade that were closely related to changes in training volume. Here, using regression analyses, we show that 54% and 39% of the variance in observed VO2max decline in male and female athletes, respectively is explained by changes in training volume. An almost linear VO2max decrease was observed in studies on young and older athletes, as well as non-athletes, starting a few days after training cessation, with a decline of as much as −20% after 12 weeks. Besides a decline in stroke volume and cardiac output, training cessation was accompanied by considerable reductions in citrate synthase and succinate dehydrogenase activity (reduction in mitochondrial content and oxidative capacity). This reduction could largely be rescued within similar time periods of training (re)uptake. It is evident that training reduction or cessation leads to a considerably accelerated VO2max drop, as compared to the gradual aging-related VO2max decline, which can rapidly nullify many of the benefits of preceding long-term training efforts.

Effects of dietary yeast β-1.3/1.6-glucans on oxidative stress biomarkers in hearts and livers of rainbow trout (Oncorhynchus mykiss Walbaum), European whitefish (Coregonus lavaretus L.), and grayling (Thymallus thymallus L.)

Abstract The present study was performed to investigate the effects of dietary yeast β-1,3/1,6-D-glucans supplemented over a 14-day feeding period on liver and cardiac function and the oxidative mechanism underlying these effects. We assessed relevant lipid peroxidation and protein oxidation biomarkers, antioxidant defense indices [superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx), total antioxidant capacity (TAC)], and biochemical alterations [activities of aminotransferases (AT), lactate dehydrogenase (LDH), and succinate dehydrogenase (SDH), and levels of lactate (L) and pyruvate (P)] in rainbow trout, European whitefish, and grayling. The fish received a control diet and an experimental diet containing yeast β-1,3/1,6-D-glucans at a dose of 1% in the basal feed for 14 days. The results demonstrated enhancement in the phagocytic activity and phagocytic index in the groups fed β-glucans, compared to the control groups. In the groups fed β-glucans, the oxidative stress parameters such as lipid peroxidation, oxidatively modified proteins, and TAC did not vary significantly. The dietary β-glucans stimulated CAT and GPx activities in hepatic and cardiac tissues in comparison to the control group; however, a reverse trend was observed in the GR activity in these tissues.

Comprehensive study of pydiflumetofen in Danio rerio: Enantioselective insight into the toxic mechanism and fate

Pydiflumetofen (PYD) is primarily used to control fungal disease. The potential risks posed by PYD enantiomers to the aquatic ecosystem are currently unclear. In this study, the enantioselective toxicity and fate of PYD in Danio rerio were investigated, and the enantioselective toxic mechanism and metabolic pathway were explored. The acute toxicity of R-PYD was 10.7-14.7-fold than that of S-PYD against Danio rerio embryos, larvae, and adults. Meanwhile, R-PYD presented a stronger effect on embryo hatching and abnormalities, adult tissue damage and oxidative stress. R-PYD inhibited the succinate dehydrogenase (SDH) activity more than S-PYD because of its better interaction with SDH with a lower binding free energy (-59.35kcal/mol), explaining the mechanism of enantioselective toxicity. Remarkable enantioselectivity was observed in uptake, distribution, and elimination. R-PYD showed preferential uptake with the higher uptake rate constants and slow metabolism with a longer half-life, resulting in the bioaccumulation of R-PYD with higher BCFk (7.37 at 0.05mg/L and 14.69 at 0.2mg/L). Besides, muscle is an important tissue for PYD accumulation, existing potential food risk. Eleven PYD metabolites were qualitatively identified, and the metabolic pathway was proposed, including hydroxylation, N-demethylation, demethoxylation, hydrolysation (phase Ⅰ), and acetylation and glucuronidation (phase Ⅱ). The predicted toxicity of the metabolite indicated that several highly toxic metabolites need to be considered in the future. This study provides a new perspective for evaluating the ecological and human health risks of chiral pesticides.

Evaluation of Effects of Selenium Nanoparticles as an Occupational and Environmental Chemical Hazard on Cellular Bioenergetic Processes

Introduction: High-volume manufacturing of selenium and a widespread use of its compounds pose potential risks to human health. Certain copper production processes emit selenium-containing nanoparticles. Objective: To assess health effects of selenium oxide nanoparticles as an industrial and environmental toxicant. Materials and methods: Selenium oxide nanoparticles (SeO NPs) were obtained by laser ablation. Their toxicity was studied both in vitro on human lung-derived embryonic fibroblasts (FLEH-104 cell line) by assaying adenosine triphosphate (ATP) bioluminescence and the rate of oxygen consumption, and in vivo on outbred albino rats by analyzing ultrastructural changes in tissues using electron microscopy, measuring succinate dehydrogenase activity of blood lymphocytes, and conducting a blood-based metabolomic test. Results: The in vitro experiment showed a decrease in ATP bioluminescence by 75.9 % and in the oxygen consumption rate of cells by 79.8 % in the incubation medium with 100 μg/mL concentration of SeO NPs. In the in vivo experiment, succinate dehydrogenase activity of blood lymphocytes decreased inversely with the increasing dose by 10.12 %, 14.0 %, 15.9 % compared to the control animals in the SeO NPs 0.1, SeO NPs 0.5, and SeO NPs 1 exposure groups, respectively. The study of ultrastructural changes in liver tissue showed a smaller number of normal mitochondria (7.78 % less in the SeO NP 1 group) compared to the controls while the metabolomic test revealed decreased acylcarnitines and increased lysophosphatidylinositols following the exposure to SeO NPs (p &gt; 0.05). Conclusion: The results of our in vitro and in vivo studies showed adverse effects of SeO NPs on bioenergetics processes in cells involving at least two mechanisms: disruption of mitochondrial β-oxidation of fatty acid and inactivation of succinate dehydrogenase. The fundamental role of the latter in the mitochondrial electron transport chain makes its vitally important for most multicellular organisms. Our findings can serve as a rationale for assessing selenium-containing nanoparticles as a chemical hazard and searching for approaches to managing their health risks.

Physiological responses in Nile tilapia (Oreochromis niloticus) induced by combined stress of environmental salinity and triphenyltin

Triphenyltin (TPT) has attracted considerable attention owing to its vitality, bioaccumulation, and lurking damage. TPT widely exists in complex salinity areas such as estuaries and coastal regions. However, there are few studies on the toxicological behavior of TPT under different salinity. In the study, juvenile Nile tilapia (Oreochromis niloticus) were utilized as model animals to investigate the effects of environmental relevant TPT exposure on the osmoregulation and energy metabolism in gill under different salinity. The results showed that salinity and TPT single or combined exposure affected the morphology of the gill tissue. After TPT exposure, Na+-K+-ATPase (NKA) activity significantly decreased at 0 ppt, while NKA and Ca2+-Mg2+-ATPase (CMA) activities significantly increased at 15 ppt. In addition, significantly higher succinate dehydrogenase (SDH) and lactate dehydrogenase (LDH) activities were found in the control fish compared to the TPT-exposed ones at 15 ppt. Quantitative real-time PCR results showed that TPT exposure affected the expression of osmoregulation and energy metabolism-related genes under different salinity. Overall, TPT exposure interfered with osmoregulation and energy metabolism under different salinity. The study will provide reference data for assessing the toxicity of organotin compounds in complex-salinity areas.

One-time ozone treatment improves the postharvest quality and antioxidant activity of Actinidia arguta fruit

The major aim of this study was to check the effect of one-time ozonation on selected quality parameters and antioxidant status of Actinidia arguta fruit. For this purpose, A. arguta fruit was ozonated with gas at a concentration of 10 and 100 ppm, which was carried out successively for 5, 15 and 30 min. Next, the selected quality attributes, antioxidants level as well as NADPH and mitochondrial energy metabolism in mini-kiwi fruit after ozonation were analysed. Our research has shown that ozonation reduced the level of yeast and mould without affecting the content of soluble solids or acidity. In turn, ozonation clearly influenced the antioxidant activity and the redox status of the fruit. The ozonated fruit was characterised by a lower level of ROS due to the higher level of low molecular weight antioxidants, as well as the higher activity of superoxide dismutase and catalase. In addition, improved quality and antioxidant activity of the fruit were indirectly due to improved energy metabolism and NADPH level. The ozonated fruit showed a higher level of ATP, due to both higher activity of succinate dehydrogenase and higher availability of NADH. Moreover, the increased level of NAD+ and the activity of NAD+ kinase and glucose-6-phosphate dehydrogenase contributed to higher levels of NADPH in the fruit.

The isolated and combined impacts of ethanol and ethylene application on sugars and organic acids dynamics in ‘Elstar’ and ‘Nicoter’ apples

The aim was to evaluate the isolated or combined effects of ethanol vapor (500 ppm) and ethylene treatments (150 ppm), on the ethylene production, respiration, sugars and organic acids dynamics of ‘Elstar’ and ‘Nicoter’ apples after harvest, during 14 d at 20 °C. Another aim was to identify at which step of fruit metabolism ethanol vapor acts. Fruit were exposed to ethanol vapor and/or ethylene for 24 h. Metabolites were evaluated at 0, 7 and 14 d at 20 °C. Ethanol vapor treatment significantly inhibited the effect of ethylene on the ethylene production and respiration, but had no significant effect on the starch metabolization and sucrose dynamics. Its application also resulted in higher succinate, malate and total organic acids concentrations. Ethanol application reduced significantly the sucrose conversion to glucose and fructose, while the ethanol + ethylene treatment resulted in high total sugars, fructose and sorbitol concentration after 14 d at 20 °C. The ethanol application (500 ppm) also affected conversion of succinate to fumarate, suggesting the succinate dehydrogenase activity as one possible action point of ethanol on the apple fruit metabolism. According to the PCA analysis, the combination of ethanol + ethylene treatments had a different response as their isolated application, affecting sugars and organic acids metabolism differently. Additionally, it can be verified that the response to treatments of both apple cultivars is differently affected by the holding time, being the response latter for ‘Nicoter’ apples when compared to ‘Elstar’.

NTiO2 alleviates the toxic effects of TCPP on mussels by adjusting respiratory metabolism and gut microbiota

As a good carrier of contaminants, nanotitanium dioxide (nTiO2) can absorb organic pollutants, producing toxicological effects on organisms. However, the complex effects of nTiO2 with contaminants on marine mussels are still unclear. In this study, we exposed mussels to tris (2-chloropropyl) phosphate (TCPP) 100 μg/L (T1), 0.5 mg/L nTiO2 + 100 μg/L TCPP (T2), 1.0 mg/L nTiO2 + 100 μg/L TCPP (T3) and control (0 nTiO2 + 0 μg/L TCPP) treatments, and assessed the combined effects of TCPP with nTiO2 on the thick-shelled mussel Mytilus coruscus by detecting the activities of gill pyruvate kinase (PK), hexokinase (HK), lactate dehydrogenase (LDH) and succinate dehydrogenase (SDH), also gill acetylcholine (Ach) and muscle lactic acid (LD) contents and gut microbiota after 14-d exposure. Compared with the control group, PK activity was increased significantly, but SDH, LDH activities and LD content were decreased significantly in T1, with the addition of nTiO2, there were not significantly different in T3. However, Ach content in T3 was significantly higher than the control and T1. Moreover, KEGG of the gut microbiota via 16 s rRNA sequencing showed that most pathways returned to the control level in T3. The results showed that TCPP affected the respiratory metabolism of mussels, changed the community structure of intestinal microflora in mussels, and nTiO2 alleviated the toxicity of TCPP. Our study provides new insights for ecological risk assessment of TCPP in bivalves in the complex aquatic environment and the novel role of nTiO2 in regulating the toxicity of TCPP.

Exogenous Melatonin Alleviated Leaf Yellowing via Inhibiting Respiration and Ethylene Biosynthesis during Shelf Life in Pakchoi.

Postharvest yellowing of leafy plant is a manifestation of senescence, and melatonin (MT) is known to delay leaf senescence in some higher plants. Herein, we investigated the effect of exogenous MT treatment on postharvest pakchoi by monitoring the ethylene biosynthesis and respiratory metabolism. Results showed that exogenous MT effectively extended the shelf life, delayed leaf yellowing, minimized the alteration in Fv/Fm ratio and maintained higher integrity of chloroplast in pakchoi. There was a significant correlation between yellowing index, respiration rate and ethylene production. MT treatments greatly delayed the yellowing process of pakchoi that was associated with the reduced activity of glycolysis pathway and tricarboxylic acid cycle (TCA), increased proportion of pentose phosphate pathway (PPP) in respiratory metabolism, as manifested by the lower activity of phosphohexose isomerase (PHI), succinate dehydrogenase (SDH) and cytochrome C oxidase (COX), downregulated the expression of their corresponding genes, but enhanced the activity and expression level of 6 phosphogluconate dehydrogenase (6PGDH). MT also markedly maintain chlorophyll content by inhibiting ethylene production and action during shelf life, likely a consequence of reduced activities of 1-aminocyclopropane-1-carboxylate (ACC) synthase (ACS) and ACC oxidase (ACO), as well as the expression levels of their related genes. These results collectively indicate that melatonin alleviated leaf yellowing of postharvest pakchoi might be attributed to the suppression of the ethylene biosynthesis and respiratory metabolism, and our findings contribute to provide a good candidate measure for extending shelf life and reducing postharvest loss of pakchoi.

The mitochondrial enzyme FAHD1 regulates complex II activity in breast cancer cells and is indispensable for basal BT-20 cells in vitro.

The mitochondrial enzyme fumarylacetoacetate hydrolase domain-containing protein 1 (FAHD1) was identified to be upregulated in breast cancer tissues. Here, we show that FAHD1 is indispensable for the survival of BT-20 cells, representing the basal breast cancer cell type. A lentiviral knock-down of FAHD1 in the breast cancer cell lines MCF-7 and BT-20 results in lower succinate dehydrogenase (complex II) activity. In luminal MCF-7 cells, this leads to reduced proliferation when cultured in medium containing only glutamine as the carbon source. Of note, both cell lines show attenuated protein levels of the enzyme glutaminase (GLS) which activates programmed cell death in BT-20. These findings demonstrate that FAHD1 is crucial for the functionality of complex II in breast cancer cells and acts on glutaminolysis in the mitochondria.

Energy status regulated umami compound metabolism in harvested shiitake mushrooms (Lentinus edodes) with spores triggered to release

The molecular mechanisms of energy status related to the umami taste of postharvest shiitake mushrooms during spore release remain poorly understood. In this study, the variations of energy status and umami taste of mushrooms were measured at 25 °C. At 24 h storage, slight spore prints of mushrooms were first pictured, respiration peaked. Significant ATP decrease and ADP increase were also observed as the initiation of postharvest senescence (P < 0.05). Meanwhile, the activities of phosphohexose isomerase, succinate dehydrogenase, glucose-6-phosphate dehydrogenase and cytochrome c oxidase and the contents of umami nucleotides and amino acids were maintained at higher levels in mushrooms with spore release. Notably, the equivalent umami concentration (EUC) was strongly correlated with energy levels (R = 0.80). Fifteen related gene expression levels in the energy metabolism pathway were downregulated. LecpdP1 and LeAK were significantly expressed in the conversion of ATP into AMP and played key roles in connecting the energy state and umami level. These results provided valuable insights on the umami taste associated with energy metabolism mechanism during postharvest mushroom spore release.