Influence of fasting on muscle composition and antioxidant defenses of market-size Sparus macrocephalus

The study was conducted to investigate fasting effects on flesh composition and antioxidant defenses of market-size Sparus macrocephalus. Two hundred fish (main initial weight 580 g) were divided into two groups (control and fasted) and reared in 6 cages. After two weeks of adaptation, group I fasted for 28 d; group II was fed normally as a control. In 3, 7, 14, 21 and 28 d, 6 fish per group were sampled for proximate flesh composition, liver antioxidant enzyme activities and malondialdehyde flesh content analyses. In fasted fish, the reduction of lipid content in muscle occurred after day 3, and, compared to controls, the content of protein decreased from day 14, the activities of liver antioxidative enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPX) increased from day 3, and flesh malondialdehyde levels increased from day 21. Flesh fat reduction shows that fasting may be used as a technique to reduce flesh lipid content in Sparus macrocephalus. However, considering flesh protein loss and the subsequent oxidative stress, the fasting technique should be used with precautions.

Antioxidant responses to benzo[a]pyrene,tributyltin and their mixture in the spleen of Sebasticus marmoratus

It has been reported that there is an interaction between Benzo[a]pyrene （BaP）, a widespread carcinogenic polycyclic aromatic hydrocarbon, and tributyltin （TBT）, an organometal used as an antifouling biocide. This study was therefore designed to examine the potential in vivo influence of BaP, TBT and their mixture on splenic antioxidant defense systems of Sebastiscus marmoratus. The fish were exposed to water containing environmentally relevant concentrations of BaP, TBT and their mixture. Spleens were collected for biochemical analysis after exposure for 7, 25, 50 d and after recovery for 7, 20 d. Cotreatment with BaP and TBT for 7 d potentiated the induction of glutathione peroxidase （GPx） activity by BaP or TBT alone. The cotreatment for 25 and 50 d resulted in inhibition of GPx activity, which was similar to the effect of TBT. Splenic glutathione S-transferase （GST） activities were significantly elevated in S. marmoratus exposed to BaP starting from 7 d and remained high up to 25 d. However, no further activity change was found with prolonged exposure. Cotreatment of BaP and TBT primarily inhibited the GST activity, which was similar to the effect of TBT. Cotreatment with BaP and TBT for 25 or 50 d potentiated the depletion of GSH （glutathione） by BaP or TBT alone. MDA （malondialdehyde） contents in spleen of S. marmoratus were not significantly altered compared with the control during the test period. Spleen, as an immune organ, is sensitive to exposure of BaP or TBT. It should have an effective mechanism to counteract oxidative damage. Antioxidative defense systems in spleen of S. marmoratus should be considered as potential biomarkers. Short-term exposure of BaP or TBT could result in induction of antioxidant defense system. A significant decrease of these indices, such as GSH, GST, GPx might indicate more severe contamination.

Responses of the antioxidant system to fluroxypyr in foxtail millet (Setaria italica L.) at the seedling stage

Foxtail millet （Setaria italica L.） is an important food and fodder crop in semi-arid areas. However, there are few herbicides suitable for use on weed control in field-grown foxtail millet during the post-emergence herbicides stage. The present study was conducted using four concentrations （0.5, 1, 2, and 4 L ai ha-1） of foliar-applied fluroxypyr, and the effect of fluroxypyr on selected metabolic and stress-related parameters in foxtail millet were assessed after 15 days. In this study, increasing concentrations decreased plant height and accumulation of chlorophylls. Our results also showed that malondialdehyde （MDA） accumulated in response to fluroxypyr application, demonstrating increased lipid peroxidation due to excessive reactive oxygen species production. In response to this oxidative stress, the activities of antioxidant enzymes were generally enhanced. Non-enzymatic antioxidant defense systems, which function in concert with antioxidant enzymes, can also protect plant cells from oxidative damage by scavenging reactive oxygen species （ROS）. In conclusion, the hybrid variety （Zhangzagu） exhibited a greater tolerance to fluroxypyr than did the conventional variety Jingu 21, which might be associated with the antioxidant mechanisms of Zhangzagu hybrid millet.

Toxic effects of crude-oil-contaminated soil in aquatic environment on Carassius auratus and their hepatic antioxidant defense system

Under the indoor simulant conditions, toxic effects of crude-oil-contaminated soil which was put into aquatic environment on the young fishes Carassius auratus and their hepatic antioxidant system after a 20-d exposure were investigated. Results showed that the relationship between the mortality of C. auratus and the exposed doses could be divided into 3 phases： fishes exposed to the low dose groups （0.5-5.0 g/L） were dead due to the ingestion of crude-oil-contaminated soils in aquatic environment; at the medium dose groups （5.0-25.0 g/L） fishes were dead due to the penetration of toxic substances; at the high dose groups （25.0-50.0 g/L） fishes were dead due to environmental stress. The highest mortality and death speed were found in the 1.0 g/L dose group, and the death speed was sharply increased in the 50.0 g/L dose group in the late phase of exposure. The activities of superoxide dismutase （SOD）, catalase （CAT） and glutathione S-transferase （GST） and the content of malaondialdehyde （MDA） in the hepatic tissues of C. auratus were induced significantly. The activity of SOD was increased and then decreased. It was significantly inhibited in the 50.0 g/L dose group. The activity of CAT was highly induced, and restored to a level which is little more than the control when the exposed doses exceeded 10.0 g/L. The activity of GST was the most sensitive, it was significantly induced in all dose groups, and the highest elevation was up to 6 times in the 0.5 g/L dose group comparing with the control. The MDA content was significantly elevated in the 50.0 g/L dose group, and the changes of the MDA content were opposite with the changes of GST activity.

Response of enzymatic and non-enzymatic antioxidant defense systems of Polygonum hydropiper to Mn stress

The response of enzyme and non-enzymatic antioxidants of Mn hyperaccumuator, Polygonum hydropiper （P. hydropiper）, to Mn stress was studied using hydroponics culture experiments to explore the mechanism of Mn tolerance in this species. Results showed that both chlorophyll and carotenoid contents significantly （p〈0.05） decreased with increasing Mn treatment levels （0, 0.5, 1, 2, 4, and 8 mg/L） in hydroponics. The concentrations of malondialdehyde （MDA） and hydrogen peroxide （H202） in the root and shoot of P hydropiper were accumulated under Mn stress. Meanwhile, the anti-oxidative functions of several important enzymes, including superoxide dismutase （SOD）, catalase （CAT）, ascorbate peroxidase （APX） and peroxidase （POD） in plants were stimulated by Mn spike in leaves and roots, especially at low Mn stress; while sulfhydryl group （--SH） and glutathion （GSH） were likely involved in Mn detoxification ofP. hydropiper under high Mn stress.

Alu antisense RNA ameliorates methylglyoxal-induced human lens epithelial cell apoptosis by enhancing antioxidant defense

AIM:To determine whether an antisense RNA corresponding to the human Alu transposable element(Aluas RNA)can protect human lens epithelial cells(HLECs)from methylglyoxal-induced apoptosis.METHODS:Cell counting kit-8(CCK-8)and 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT)assays were used to assess HLEC viability.HLEC viability/death was detected using a Calcein-AM/PI double staining kit;the annexin V-FITC method was used to detect HLEC apoptosis.The cytosolic reactive oxygen species(ROS)levels in HLECs were determined using a reactive species assay kit.The levels of malondialdehyde(MDA)and the antioxidant activities of total-superoxide dismutase(T-SOD)and glutathione peroxidase(GSH-Px)were assessed in HLECs using their respective kits.RT-q PCR and Western blotting were used to measure m RNA and protein expression levels of the genes.RESULTS:Aluas RNA rescued methylglyoxal-induced apoptosis in HLECs and ameliorated both the methylglyoxalinduced decrease in Bcl-2 m RNA and the methylglyoxalinduced increase in Bax m RNA.In addition,Aluas RNA inhibited the methylglyoxal-induced increase in Alu sense RNA expression.Aluas RNA inhibited the production of ROS induced by methylglyoxal,restored T-SOD and GSHPx activity,and moderated the increase in MDA content after treatment with methylglyoxal.Aluas RNA significantly restored the methylglyoxal-induced down-regulation of Nrf2 gene and antioxidant defense genes,including glutathione peroxidase,heme oxygenase 1,γ-glutamylcysteine synthetase and quinone oxidoreductase 1.Aluas RNA ameliorated methylglyoxal-induced increases of the m RNA and protein expression of Keap1 that is the negative regulator of Nrf2.CONCLUSION:Aluas RNA reduces apoptosis induced by methylglyoxal by enhancing antioxidant defense.

Changes in Growth,Photosynthetic Pigments,Cell Viability,Lipid Peroxidation and Antioxidant Defense System in Two Varieties of Chickpea(Cicer arietinum L.)Subjected to Salinity Stress

Salinity is one of the most severe abiotic stresses for crop production.The present study investigates the salinityinduced modulation in growth indicators,morphology and movement of stomata,photosynthetic pigments,activity of carbonic anhydrase as well as nitrate reductase,and antioxidant systems in two varieties of chickpea(Pusa-BG5023,and Pusa-BGD72).On 20^(th) day of sowing,plants were treated with varying levels of NaCl(0,50,100,150 and 200 mM)followed by sampling on 45 days of sowing.Recorded observations on both the varieties reveal that salt stress leads to a significant decline in growth,dry biomass,leaf area,photosynthetic pigments,protein content,stomatal behavior,cell viability,activity of nitrate reductase and carbonic anhydrase with the rise in the concentration of salt.However,quantitatively these changes were less in Pusa-BG5023 as compared to Pusa-BGD72.Furthermore,salinity-induced oxidative stress enhanced malondialdehyde content,superoxide radicals,foliar proline content,and the enzymatic activities of superoxide dismutase,catalase,and peroxidase.The variety Pusa-BGD72 was found more sensitive than Pusa-BG5023 to salt stress.Out of different graded concentrations(50,100,150 and 200 mM)of sodium chloride,50 mM was least toxic,and 200 mM was most damaging.The differential behavior of these two varieties measured in terms of stomatal behavior,cell viability,photosynthetic pigments,and antioxidant defense system can be used as prospective indicators for selection of chickpea plants for salt tolerance and sensitivity.

Organic Amendments Improve Plant Morpho-Physiology and Antioxidant Metabolism in Mitigating Drought Stress in Bread Wheat(Triticum aestivum L.)

Due to the unpredictable climate change,drought stress is being considered as one of the major threats to crop production.Wheat(Triticum aestivum L.cv.BARI Gom-26)being a dry season crop frequently faces scarcity of water and results in a lower yield.Therefore,this experiment aims to explore the role of different organic amendments(OAs)in mitigating drought stress-induced damage.The pot experiment consisted of different organic amendments viz.compost,vermicompost and poultry manure@0.09 kg m^(−2)soil,biochar@2.5%w/w soil and chitosan@1%w/w soil which was imposed on the plants grown under both well-watered and drought conditions.Results showed that drought stress reduced plant height(15%),SPAD value(16%),relative water content(13%),number of spikelet spike^(−1)(17%),number of grains spike^(−1)(12%),and 100-grain weight(18%).Organic amendments act as a protectant and reduce drought stress-induced damages by enhancing the morpho-physiological and yield attributes.Vermicompost enhanced SPAD value by 18%,number of spikelets spike^(−1)by 20%,number of grains spike^(−1)by 17%,whereas poultry manure increased plant height by 16%under drought condition compared to control plant.Unlike other OAs applied,vermicompost was proved to be capable of reducing the higher lipid peroxidation and proline content raised by drought condition.Drought stress-induced increment of catalase,ascorbate peroxidase and glutathione reductase activities were also efficiently modulated by the organic amendment application.The present study concluded that OAs play significant roles in alleviating drought stressinduced damages by improving the morpho-physiological attributes and among the different types of OAs used vermicompost performed better which in addition ceased the production of reactive oxygen species.

Mycorrhiza improves cold tolerance of Satsuma orange by inducing antioxidant enzyme gene expression

A potted experiment was carried out to study the effect of an arbuscular mycorrhizal fungus(Diversispora versiformis)and arbuscular mycorrhizal like fungus(Piriformospora indica)on antioxidant enzyme defense system of Satsuma orange(Citrus sinensis cv.Oita 4)grafted on Poncirus trifoliata under favourable temperature(25°C)and cold temperature(0°C)for 12 h.Such short-term treatment of cold temperature did not cause any significant change in root fungal colonization and spore density in soil.Under cold stress,D.versiformis inoculation did not change the activity of superoxide dismutase(SOD),catalase(CAT),and peroxidase(POD)in leaves and roots,whereas P.indica inoculation significantly increased the activity of CAT in roots and POD in leaves only.In addition,inoculation of two mycorrhizal fungi under cold stress significantly increased the relative expression levels of PtPOD and PtF-SOD in leaves,P.indica up-regulated the expression levels of PtCu/Zn-SOD in leaves,and D.versiformis also induced the expression levels of PtMn-SOD and PtCAT1 in leaves.In addition,inoculated Oita 4 trees maintained significantly lower hydrogen peroxide levels and malondialdehyde contents in leaves and roots under cold temperature,suggesting lower oxidative damage.Therefore,we concluded that arbuscular mycorrhizal fungi(especially P.indica)mainly induced the expression of antioxidant enzyme genes,depending on the fungal species,and thus mitigated oxidative damage for higher cold resistance in inoculated plants.

Antioxidant defense mechanisms and fatty acid catabolism in Red-billed Leiothrix(Leiothrix lutea)exposed to high temperatures

Extreme hot weather is occurring more frequently due to global warming,posing a significant threat to species survival.Birds in particular are more likely to overheat in hot weather because they have a higher body temperature.This study used a heat stress model to investigate the antioxidant defense mechanisms and changes in fatty acid catabolism in Red-billed Leiothrix(Leiothrix lutea)to gain an understanding of how birds adapt to high temperatures.The birds were divided into five groups:a control group(30℃for 0 days),1 D group(40℃for 1 day),3 D group(40℃for 3 days),14 D group(40℃for 14 days)and recovery group(40℃for 14 days,then 30℃for 14 days).Our results indicated that when Red-billed Leiothrix are subjected to heat stress,malondialdehyde(MDA)content in the liver significantly increased,as did the enzyme activities of catalase(CAT),glutathione-SH-peroxidase(GSH-PX)and total antioxidant capacity(T-AOC)in the liver.Furthermore,there was a significant increase in heat shock protein 70(HSP70)expression in the liver,while avian uncoupling protein(avUCP)expression in muscle was significantly reduced.Additionally,there was a significant reduction in fatty acid catabolism enzyme activity such as 3-hydroxyacyl-CoAdehydrogenase(HOAD)activity in the heart,and carnitine palmitoyl transferase 1(CPT-1)and citrate synthase(CS)activity in the heart and liver.Furthermore,fatty acid translocase(FAT/CD36)in the heart,heart-type fatty acid binding protein(H-FABP)and fatty acid binding protein(FABP-pm)in the liver and heart were also significantly decreased.These changes reverted after treatment,but not to the same level as the control group.Our results indicated that when Red-billed Leiothrix are exposed to heat stress their internal antioxidant defense system is activated to counteract the damage caused by high temperatures.However,even with high antioxidant levels,prolonged high temperature exposure still caused some degree of oxidative damage possibly requiring a longer recovery time.Additionally,Red-billed Leiothrix may be able to resist heat stress by reducing fatty acid transport and catabolism.

Silicon and Nitric Oxide-Mediated Regulation of Growth Attributes, Metabolites and Antioxidant Defense System of Radish (Raphanus sativus L.) under Arsenic Stress

Arsenic(As)contaminated food chains have emerged as a serious public concern for humans and animals and are known to affect the cultivation of edible crops throughout the world.Therefore,the present study was designed to investigate the individual as well as the combined effects of exogenous silicon(Si)and sodium nitroprusside(SNP),a nitric oxide(NO)donor,on plant growth,metabolites,and antioxidant defense systems of radish(Raphanus sativus L.)plants under three different concentrations of As stress,i.e.,0.3,0.5,and 0.7 mM in a pot experiment.The results showed that As stress reduced the growth parameters of radish plants by increasing the level of oxidative stress markers,i.e.,malondialdehyde and hydrogen peroxide.However,foliar application of Si(2 mM)and pretreatment with SNP(100μM)alone as well as in combination with Si improved the plant growth parameters,i.e.,root length,fresh and dry weight of plants under As stress.Furthermore,As stress also reduced protein,and metabolites contents(flavonoids,phenolic and anthocyanin).Activities of antioxidative enzymes such as catalase(CAT),ascorbate peroxidase(APX),guaiacol peroxidase(POD),and polyphenol oxidase(PPO),as well as the content of non-enzymatic antioxidants(glutathione and ascorbic acid)decreased under As stress.In most of the parameters in radish,As III concentration showed maximum reduction,as compared to As I and II concentrations.However,the individual and combined application of Si and NO significantly alleviated the As-mediated oxidative stress in radish plants by increasing the protein,and metabolites content.Enhancement in the activities of CAT,APX,POD and PPO enzymes were recorded.Contents of glutathione and ascorbic acid were also enhanced in response to co-application of Si and NO under As stress.Results obtained were more pronounced when Si and NO were applied in combination under As stress,as compared to their individual application.In short,the current study highlights that Si and NO synergistically regulate plant growth through lowering the As-mediated oxidative stress by upregulating the metabolites content,activity of antioxidative enzymes and non-enzymatic antioxidants in radish plants.

Therapeutic implications of antioxidant defense in acute pancreatitis

Acute pancreatitis is an inflammation initially localized in the pancreas,which may be accompanied with severe complications such as multi-organ failure,gastrointestinal hemorrhage and malnutrition.One in ten severe cases of acute pancreatitis develops systemic inflammatory response syndrome.Despite treatment,acute pancreatitis can be a life-threatening disease as its mortality rate amounts to 5%-10%in general,and up to 35%in cases of severe course.[1]Over the years,the role of oxidative stress

Response of antioxidant defense system in copepod Calanus sinicus Brodsky exposed to CO_2-acidified seawater

Marine zooplankton responds sensitively to elevated seawater CO_2 concentration. However, the underlying physiological mechanisms have not been studied well. We therefore investigated the effects of elevated CO_2concentration（0.08%, 0.20%, 0.50% and 1.00%） on antioxidant defense components, as well as two detoxification enzymes of Calanus sinicus（copepod）. The results showed that glutathione peroxidase（GPx） activity exposed to CO_2-acidified seawater was significantly stimulated while other antioxidant components, including glutathione-Stransferase（GST） activity, superoxide dismutase（SOD） activity decreased significantly with reduced glutathione（GSH） level and GSH/oxidized glutathione（GSSG） value. CO_2-acidified seawater exhibited stimulatory effects on adenosine triphosphatase（ATPase） activity and acetylcholinesterase（Ach E） activity was inhibited. Moreover, the results of principal component analysis indicated that 75.93% of the overall variance was explained by the first two principal components. The elevated CO_2 concentration may affect the metabolism and survivals of copepods through impacts these enzymes activities. Further studies are needed to focus on the synergistic effects of elevated CO_2 concentration and other environmental factors on copepods.

Grain Yield,Biomass Accumulation,and Leaf Photosynthetic Characteristics of Rice under Combined Salinity-Drought Stress

Simultaneous stresses of salinity and drought often coincide during rice-growing seasons in saline lands,primarily due to insufficient water resources and inadequate irrigation facilities.Consequently,combined salinity-drought stress poses a major threat to rice production.In this study,two salinity levels(NS,non-salinity;HS,high salinity)along with three drought treatments(CC,control condition;DJ,drought stress imposed at jointing;DH,drought stress imposed at heading)were performed to investigate their combined influences on leaf photosynthetic characteristics,biomass accumulation,and rice yield formation.Salinity,drought,and their combination led to a shortened growth period from heading to maturity,resulting in a reduced overall growth duration.Grain yield was reduced under both salinity and drought stress,with a more substantial reduction under the combined salinity-drought stress.The combined stress imposed at heading caused greater yield losses in rice compared with the stress imposed at jointing.Additionally,the combined salinity-drought stress induced greater decreases in shoot biomass accumulation from heading to maturity,as well as in shoot biomass and nonstructural carbohydrate(NSC)content in the stem at heading and maturity.However,it increased the harvest index and NSC remobilization reserve.Salinity and drought reduced the leaf area index and SPAD value of flag leaves and weakened the leaf photosynthetic characteristics as indicated by lower photosynthetic rates,transpiration rates,and stomatal conductance.These reductions were more pronounced under the combined stress.Salinity,drought,and especially their combination,decreased the activities of ascorbate peroxidase,catalase,and superoxide dismutase,while increasing the contents of malondialdehyde,hydrogen peroxide,and superoxide radical.Our results indicated a more significant yield loss in rice when subjected to combined salinity-drought stress.The individual and combined stresses of salinity and drought diminished antioxidant enzyme activities,inhibited leaf photosynthetic functions,accelerated leaf senescence,and subsequently lowered assimilate accumulation and grain yield.

Oxidative stress indicators in human and bottlenose dolphin leukocytes in response to a pro-inflammatory challenge

Marine mammals undergo cycles of tissue ischemia and reperfusion during the dive response.Reperfusion injury can result in oxidative tissue damage and the activation of a pro-inflammatory immune response.The risk of oxidative damage is reduced by antioxidants.Our hypothesis is that the reported higher antioxidant defenses within marine mammal tissues provide additional protection in situations that produce oxidative stress,like inflammation,in comparison to terrestrial mammal tissues.Leukocytes were isolated from the whole blood of Pacific bottlenose dolphins(Tursiops truncatus gilli)and humans(Homo sapiens)and were exposed to lipopolysaccharides(LPS,10μg/mL)in vitro to simulate a pro-inflammatory challenge.Oxidative stress indicators,including superoxide radical(O_(2)^(•−))production,activities of superoxide dismutase(SOD),catalase(CAT),glutathione peroxidase(GPx),glutathione reductase(GR),and glutathione S-transferase(GST),as well as oxidative protein damage,were quantified by spectrophotometry.Following 48 h under experimental conditions,bottlenose dolphin leukocytes produced 1.9 times more O_(2)^(•−)but displayed 2.0 times lower protein carbonyl concentrations compared to human leukocytes.Following 48 h under experimental conditions,bottlenose dolphin leukocytes displayed 7.9,2.0,11.1,and 3.3 times more activities of CAT,GPx,GR,and GST,respectively,compared to human leukocytes.These results suggest that,under cell culture conditions,the antioxidant defenses in bottlenose dolphin leukocytes provide additional protection against pro-inflammatory challenges in comparison to human leukocytes,likely as an adaptive advantage.

Cross-talk between calcium-calmodulin and nitric oxide in abscisic acid signaling in leaves of maize plants

Using pharmacological and biochemical approaches, the signaling pathways between hydrogen peroxide （H2O2）, calcium （Ca^2＋）-calmodulin （CAM）, and nitric oxide （NO） in abscisic acid （ABA）-induced antioxidant defense were investigated in leaves of maize （Zea mays L.） plants. Treatments with ABA, H2O2, and CaCl2 induced increases in the generation of NO in maize mesophyll cells and the activity of nitric oxide synthase （NOS） in the cytosolic and microsomal fractions of maize leaves. However, such increases were blocked by the pretreatments with Ca^2＋ inhibitors and CaM antagonists. Meanwhile, pretreatments with two NOS inhibitors also suppressed the Ca^2＋-induced increase in the production of NO. On the other hand, treatments with ABA and the NO donor sodium nitroprusside （SNP） also led to increases in the concentration of cytosolic Ca^2＋ in protoplasts of mesophyll cells and in the expression of calmodulin 1 （CaM1） gene and the contents of CaM in leaves of maize plants, and the increases induced by ABA were reduced by the pretreatments with a NO scavenger and a NOS inhibitor. Moreover, SNP-induced increases in the expression of the antioxidant genes superoxide dismutase 4 （SOD4）, cytosolic ascorbate peroxidase （cAPX）, and glutathione reductase 1 （GR1） and the activities of the chloroplastic and cytosolic antioxidant enzymes were arrested by the pretreatments with Ca^2＋ inhibitors and CaM antagonists. Our results suggest that Ca^2＋-CaM functions both upstream and downstream of NO production, which is mainly from NOS, in ABA- and H2O2-induced antioxidant defense in leaves of maize plants.

Impact of ocean acidification on physiology and microbiota in hepatopancreas of Pacific oyster Crassostrea gigas

The hepatopancreas is an important tissue involved in various biological metabolism for mollusks,but its responses to ocean acidifi cation(OA)have not been well evaluated.In this study,the oysters were cultured in simulated conditions by continuously bubbling with ambient air(pH=8.10)or air-CO_(2)(pH=7.50)for up to two months,and the variations on the antioxidant capacity,digestive ability,and microbiota composition in hepatopancreas of Crassostrea gigas were analyzed.The results show that although superoxide dismutase and glutathione responded quickly to OA stress,the antioxidant capacity of the hepatopancreas was inhibited,as revealed by the decrease of the total antioxidant capacity,which led to an upward trend of the malondialdehyde,demonstrating that the oxidative damages were accumulated under the OA process.The determination of the digestive ability manifested as the decrease of pepsin activity and the recovery of lipase and amylase activity after long-term acidifi cation,which may be helpful to improve the adaptability of oysters.In addition,analysis on 16S rDNA amplicon revealed that the total species abundance and diversity of the hepatopancreas microbiota experienced a dynamic change,but fi nally it decreased greatly after long-term acidifi cation.The structure of the hepatopancreas microbiota was changed drastically with the change of the dominant species from aerobic to the anaerobic and facultative anaerobic bacteria,and the abnormal proliferation of some species,such as genus of Mycoplasma and order Clostridiales,which may aggravate the adverse eff ects of OA on the physiological functions of the hepatopancreas.As a result,our fi ndings enrich our understanding of the accumulated oxidative damage and adaptive digestive ability in oyster hepatopancreas caused by OA.For the fi rst time,the changes of the hepatopancreas microbiota under long-term acidifi cation conditions are described,proving a good reference for the study of the response and adaptation mechanisms of bivalve mollusks in a wide range of oceans OA.

Role of CaCl_2 in Cold Acclimation-Induced Freezing Resistance of Populus tomentosa Cuttings

To explore the antioxidant defense system of Populus tomentosa cuttings subjected to salt stress, the cuttings were treated with three different concentrations (85?mmol·L -1 , 170?mmol·L -1 , 260?mmol·L -1 ) of NaCl for 3\|54?h, and the changes in superoxide dismutase (SOD) and peroxidase (POD) activities, and malondialdehyde (MDA) content in the leaves of cuttings were investigated. The results showed that SOD and POD activities significantly decreased during 3?h at the beginning of all NaCl treatment, and then slightly decreased during a period of 9\|54?h, but a lower decrease in SOD activity than in POD activity was observed in all treated cuttings. MDA content distinctly increased and reached a maximum value during 15?h after the beginning of salt stress, and then decreased, but its level was higher than the control. The decreased SOD and POD activities and the increased MDA content affected by the treatment of 260?mmol·L -1 NaCl were more obvious than that affected by the treatment of 85?mmol·L -1 or 170?mmol·L -1 NaCl. It is possible that the decrease in SOD and POD activities under salt stress resulted in the enhancement of membrane lipid peroxidation, which seems to be the key factor that leads to the increase of MDA content and the occurrence of oxidative damage to cuttings.

Ameliorative Effects of Brassinosteroid on Excess Manganese-Induced Oxidative Stress in Zea mays L. Leaves

Manganese （Mn） is becoming an important factor limiting crop growth and yields especially on acid soils. The present study was designed to explore the hypothesis that brassinosteroid application can enhance the tolerance of maize （Zea mays L.） to Mn stress and if so, whether or not the mechanism underlying involves regulation of antioxidative metabolism in leaves. The effects of 24-epibrassinosteroid （EBR） on the growth, photosynthesis, water status, lipid peroxidation, accumulation of reactive oxygen species, and activities or contents of antioxidant defense system in maize plants under Mn stress were investigated by a pot experiment. At supplemented Mn concentrations of 150-750 mg kg^-1 soil, the growth of plants was inhibited in a concentration-dependent manner. The semi-lethal concentration was 550 mg Mn kgq soil. Foliage application with 0.1 mg L^-1 EBR significantly reduced the decrease in dry mass, chlorophyll content, photosynthetic rate, leaf water content, and water potential of plants grown in the soil spiked with 550 mg kg^-1 Mn. The oxidative stress caused by excess Mn, as reflected by the increase in malondialdehyde （MDA） content and lipoxygenase （LOX, EC 1.13.11.12） activity, accumulation of superoxide radical and H2O2, was greatly decreased by EBR treatment. Further investigations revealed that EBR application enhanced the activities of superoxide dismutase （SOD, EC 1.15.1.1）, peroxidase （POD, EC 1.11.1.7）, catalase （EC 1.11.1.6）, ascorbate peroxidase （APX, EC 1.11. 1.11）, dehydroascorbate reductase （DHAR, EC 1.8.5.1）, and glutathione reductase （GR, EC 1.6.4.2）, and the contents of reduced ascorbate and glutathione, compared with the plants without EBR treatment. It is concluded that the ameliorative effects of EBR on Mn toxicity are due to the upregulation of antioxidative capacity in maize under Mn stress.

Impact of nanomaterials on plants:What other implications do they have?

The use of nanomaterials has spread and has been applied in different industries,including agriculture.Here,the possibilities presented by NMs are very varied,from the biostimulation of favorable responses,or the control of pests and diseases,to the monitoring of characteristics of interest with the use of nanosensors.Particularly the biostimulation of agricultural crops with the use of nanomaterials is very relevant,since from this process stress tolerance,higher content of biocompounds,etc.,can be induced.Although the positive impacts on crops are clear,there is not enough information to determine the long-term impacts,both on ecosystems and on human health.