Differential gene expression in Daphnia magna suggests distinct modes of action and bioavailability for ZnO nanoparticles and Zn ions

Zinc oxide nanoparticles (ZnO NPs) are being rapidly developed for use in consumer products, wastewater treatment, and chemotherapy providing several possible routes for ZnO NP exposure to humans and aquatic organisms. Recent studies have shown that ZnO NPs undergo rapid dissolution to Zn(2+), but the relative contribution of Zn(2+) to ZnO NP bioavailability and toxicity is not clear. We show that a fraction of the ZnO NPs in suspension dissolves, and this fraction cannot account for the toxicity of the ZnO NP suspensions to Daphnia magna. Gene expression profiling of D. magna exposed to ZnO NPs or ZnSO(4) at sublethal concentrations revealed distinct modes of toxicity. There was also little overlap in gene expression between ZnO NPs and SiO(x) NPs, suggesting specificity for the ZnO NP expression profile. ZnO NPs effected expression of genes involved in cytoskeletal transport, cellular respiration, and reproduction. A specific pattern of differential expression of three biomarker genes including a multicystatin, ferritin, and C1q containing gene were confirmed for ZnO NP exposure and provide a suite of biomarkers for identifying environmental exposure to ZnO NPs and differentiating between NP and ionic exposure.     

肺炎克雷伯菌对H2O2氧化胁迫的响应机制研究

目的:研究宿主肠道氧化条件对肺炎克雷伯菌的影响及该菌响应氧化胁迫的机制。方法:通过体外模拟肠道氧化条件,将肺炎克雷伯菌接种在含不同浓度梯度H₂O₂的液体培养基中进行氧化胁迫处理;测定细菌的生长曲线、检测细菌的关键毒力因子-荚膜与生物膜的生成量。并进一步地利用qRT-PCR荧光定量分析荚膜与生物膜表型相关基因的表达差异。结果:在氧化因子胁迫下,当处于较低浓度范围(<1.56 mmol/L)时,肺炎克雷伯菌早期生长受到抑制作用,中后期逐渐适应胁迫、其生长未受明显影响。此外,肺炎克雷伯菌在氧化胁迫条件下荚膜生成量明显降低,呈剂量依赖效应;但在一定浓度范围氧化因子作用下,其生物膜的形成量增加。分子检测表明荚膜结构基因magA表达量明显下调,生物膜相关基因YbaJ出现显著的上调表达。结论:肺炎克雷伯菌通过上调YbaJ基因的表达促进毒力因子生物膜形成以此响应氧化因子胁迫,本研究可为食源性肺炎克雷伯菌与宿主肠道因子互作及致病机制研究提供新思路。

     

Toxicogenomic responses of nanotoxicity in Daphnia magna exposed to silver nitrate and coated silver nanoparticles

Applications for silver nanomaterials in consumer products are rapidly expanding, creating an urgent need for toxicological examination of the exposure potential and ecological effects of silver nanoparticles (AgNPs). The integration of genomic techniques into environmental toxicology has presented new avenues to develop exposure biomarkers and investigate the mode of toxicity of novel chemicals. In the present study we used a 15k oligonucleotide microarray for Daphnia magna, a freshwater crustacean and common indicator species for toxicity, to differentiate between particle specific and ionic silver toxicity and to develop exposure biomarkers for citrate-coated and PVP-coated AgNPs. Gene expression profiles revealed that AgNO(3) and AgNPs have distinct expression profiles suggesting different modes of toxicity. Major biological processes disrupted by the AgNPs include protein metabolism and signal transduction. In contrast, AgNO(3) caused a downregulation of developmental processes, particularly in sensory development. Metal responsive and DNA damage repair genes were induced by the PVP AgNPs, but not the other treatments. In addition, two specific biomarkers were developed for the environmental detection of PVP AgNPs; although further verification under different environmental conditions is needed.     

甜菜碱保护细胞免受AAPH损伤的研究

为了评价甜菜碱的抗氧化活性,本文研究了甜菜碱对受AAPH诱导产生的自由基损伤的红细胞和肝细胞的影响。结果显示当甜菜碱的浓度达到200 mmol/L时,AAPH诱导的红细胞氧化溶血率降低了54.19%,MDA降低了4.32 nmol/mg;电镜下阳性损伤组红细胞胞膜皱缩明显、棘突较多、呈星状改变,而保护组胞膜只是略有皱缩,恢复至阴性组正常细胞形态;同时经甜菜碱处理,阳性损伤组红细胞胞内ROS含量降低了57.16 IU/mg,SOD、CAT、GPx酶活分别降低了9.84 m U/mg、13.91 m U/mg和43.59 m U/mg,并与阴性对照组无显著性差异;在正常肝细胞中,50 mmol/L甜菜碱使AAPH损伤的细胞内MDA下降了0.21 nmol/mg,SOD、CAT酶活则分别下降了173.21 U/mg和53.9U/mg,与阴性组正常组肝细胞无显著性差异。综上分析,甜菜碱能很好的保护细胞免受AAPH产生的自由基的损伤,说明甜菜碱具有良好的抗氧化作用。     

Oxidative stability of tuna fat spreads (O/W/O emulsions) using conventional lipid oxidation methods, SPME-GC/MS and sensory analysis

Oxidative analysis of omega-3-enriched fat spreads (oil-in-water-in-oil, O/W/O emulsions) was carried out using conventional lipid oxidation methods (lipid hydroperoxide and p-Anisidine values) and compared with volatile compound analysis using SPME-GC/MS and sensory evaluation. Fat spreads were produced using novel double-emulsion technology. More volatile compounds were detected in tuna oil-enriched spreads (Ross and Smith in Compr Rev Food Sci Food Saf 5:18–25, 2006) than control (no tuna oil) (Lund and Hølmer in Eur Food Res Technol 212:636–642, 2001). As storage time of spreads increased, volatile concentration increased. Conventional lipid oxidation results correlated well with the GC/MS results, as the tuna spread had consistently higher values than the control spread. Lipid hydroperoxides and GC/MS volatile compounds increased with storage time, whereas p-Anisidine values remained level. The control spread achieved the highest score from the sensory panel for odour and flavour acceptability. Flavour of all tuna spreads became unacceptable after 8 weeks. To the authors’ knowledge, this is the first study-detecting volatiles using SPME-GC/MS, in omega-3-enriched double-emulsion fat spreads.     

Behavioral and physiological changes in Daphnia magna when exposed to nanoparticle suspensions (titanium dioxide, nano-C60, and C60HxC70Hx)

Little is known aboutthe impact manufactured nanoparticles will have on aquatic organisms. Previously, we demonstrated that toxicity differs with nanoparticle type and preparation and observed behavioral changes upon exposure to the more lethal nanoparticle suspensions. In this experiment, we quantified these behavioral and physiological responses of Daphnia magna at sublethal nanoparticle concentrations. Titanium dioxide (TiO2) and fullerenes (nano-C60) were chosen for their potential use in technology. Other studies suggest that addition of functional groups to particles can affect their toxicity to cell cultures, but it is unknown if the same is true at the whole organism level. Therefore, a fullerene derivative, C60HxC70Hx, was also used to examine how functional groups affect Daphnia response. Using a high-speed camera, we quantified several behavior and physiological parameters including hopping frequency, feeding appendage and postabdominal curling movement, and heart rate. Nano-C60 was the only suspension to cause a significant change in heart rate. Exposure to both nano-C60 and C60HxC70Hx suspensions caused hopping frequency and appendage movement to increase. These results are associated with increased risk of predation and reproductive decline. They indicate that certain nanoparticle types may have impacts on population and food web dynamics in aquatic systems.     

血管紧张素转移酶2(ACE2)在糖尿病致大鼠肝脏氧化应激损伤中的作用及机制分析

目的：探讨血管紧张素转移酶2(ACE2)在糖尿病致大鼠肝脏氧化应激损伤中的作用和可能机制。方法：24只健康雄性SD大鼠,随机选取8只作为正常对照组,剩余16只按60mg/kg(以体质量计)一次性腹腔注射STZ溶液制备糖尿病肝脏氧化应激损伤模型,成模后大鼠随机分为2组：糖尿病组和胰岛素治疗组(优泌林 3.7×10-8mol/d),30d后宰杀,取血液和肝脏组织等进行各指标测定：1)测定血清中AGEs含量;2)测定肝脏组织中过氧化氢(H2O2)、丙二醛(MDA)的含量及过氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)的活力;3) 肝脏组织中血管紧张素Ⅱ(AngⅡ)、血管紧张素1-7(Ang1-7)的含量,ACE和ACE2酶活力的测定。结果：1)正常对照组大鼠空腹血糖均值为(5.39±0.30)mmol/L,糖尿病组大鼠空腹血糖均值持续维持在(28.24±2.51)mmol/L(远高于高水平高血糖状态指标值16.6mmol/L),胰岛素治疗后大鼠空腹血糖水平明显下降至(11.18±1.26)mmol/L,显著高于正常对照组(P＜0.05),但同时显著低于糖尿病组(P＜0.05),且治疗后期已经低于10.0mmol/L并逐渐接近正常对照组。糖尿病组大鼠血清中的AGEs的含量显著高于正常对照组和胰岛素治疗组(P＜0.05)。2) 与正常对照组和胰岛素治疗组相比,糖尿病组大鼠肝脏组织中的MDA和H2O2极显著增多(P＜0.01),SOD和GSH-Px的活力极显著降低(P＜0.01); AngⅡ的含量显著增多(P＜0.01),Ang1-7含量显著降低(P＜0.01),ACE的酶活力显著升高(P＜0.01),而ACE2的酶活力显著降低(P＜0.01)。 结论： 糖尿病时大鼠肝脏组织局部AngⅡ显著升高,ACE2活力下降,肝脏组织处于氧化应激状态。胰岛素治疗后,ACE2活力增高,致AngⅡ降解,AngⅡ含量显著降低,肝脏的氧化应激减缓,提示ACE2对糖尿病大鼠肝脏氧化应激损伤有一定的保护作用,其机理可能与对AngⅡ降解作用增强有关。     

纳豆抗氧化肽对H2O2诱导HEK293细胞氧化应激损伤的保护作用

目的 评价纳豆肽的抗氧化能力以及对氧化应激HEK293细胞的保护效果。方法 首先以DPPH、ABTS+、·OH和O2-清除能力以及总还原能力为指标,测定酶解得到纳豆肽粗品的抗氧化能力。利用超滤技术对纳豆肽进行分离,测定分离后各组分在不同浓度下对DPPH及ABTS+清除活性。将活性最强的两个组分作为纳豆抗氧化肽,测定它们对H2O2诱导氧化损伤HEK293细胞抗氧化酶含量的影响,评价其对氧化损伤HEK293细胞的保护效果。结果 纳豆肽粗品在8 mg/mL时具有良好的DPPH、ABTS+、·OH和O2-清除能力以及总还原能力,初步证实了其抗氧化潜力。超滤后得到了相对分子质量分别大于30 kDa、10~30 kDa、3~10 kDa、小于3 kDa的四个纳豆肽组分,其对DPPH及ABTS+清除活性均随着浓度的增加呈现上升趋势,特别是在8 mg/mL时,相对分子质量为3~10 kDa和小于3 kDa组分表现出最强的抗氧化活性,将这两个组分作为纳豆抗氧化肽继续研究。后续的细胞试验表明,这两个组分能够显著提高氧化应激下HEK293细胞的存活率。在50~300μg/mL的剂量范围内,小于3 kDa组分的纳豆抗氧化肽可使细胞存活率恢复至未损伤时的水平,而3~10 kDa组分也使损伤细胞的存活率提高了40.8%。同时,纳豆抗氧化肽均能提高氧化损伤HEK293细胞中的SOD、GPX和CAT等抗氧化酶的含量,小于3 kDa组分和3~10 kDa组分的纳豆抗氧化肽分别使SOD含量提高了49.52%和50.80%,GPX含量提高了49.52%和50.81%,CAT含量提高了93.64%和91.97%。结论 纳豆抗氧化肽可以有效地缓解H2O2诱导的HEK293细胞的氧化应激损伤,为纳豆抗氧化肽的应用提供理论依据。     

松多酚激活Nrf2/ARE通路对H_2O_2致牛肺动脉内皮细胞氧化应激损伤的保护作用

本文研究了松多酚对H_2O_2致牛肺动脉内皮细胞(BPAECs)氧化应激损伤的保护作用及其相关机制。以H_2O_2100μM诱导牛肺动脉内皮细胞(BPAECs)建立氧化损伤模型,实验设对照组、模型组、松多酚高、中、低(0.5、0.1、0.05 mg/m L)剂量组,免疫荧光检测转录因子NF-E 2相关因子2(Nrf2)核转位变化;RT-PCR检测Nrf2 m RNA的表达;Western blot检测Nrf2蛋白的表达;以及应用抑制剂筛选其发挥抗氧化损伤保护作用的信号通路。松多酚可以促进H_2O_2所致氧化损伤的牛肺动脉内皮细胞中的Nrf2从细胞质向细胞核内的转移,相对于模型组,松多酚提取物可以增加Nrf2 m RNA和蛋白质水平的表达量(*p0.05,**p0.01),且呈剂量-效应关系(**p0.01)。松多酚对H_2O_2诱导氧化损伤的BPAECs具有保护作用,激活Nrf2/ARE机制可能与COX-2、p38、PI3K/AKT信号通路有关,而与PKC信号通路无关。     

Influence of polyethyleneimine graftings of multi-walled carbon nanotubes on their accumulation and elimination by and toxicity to Daphnia magna

Modifications of carbon nanotubes (CNTs) for different applications may change their physicochemical properties such as surface charge. Assessments of the extent to which such modifications influence CNT ecotoxicity, accumulation, and elimination behaviors are needed to understand potential environmental risks these variously modified nanoparticles may pose. We have modified carbon-14 labeled multi-walled carbon nanotubes (MWNTs) with polyethyleneimine (PEI) surface coatings to increase their aqueous stability and to give them positive, negative, or neutral surface charges. Uptake and elimination behaviors of Daphnia magna exposed to PEI-coated and acid-modified MWNTs at concentrations of approximately 25 and 250 μg/L were quantified. PEI surface coatings did not appear to substantially impact nanotube accumulation or elimination rates. Although the PEI-modified nanotubes exhibited enhanced stability in aqueous solutions, they appeared to aggregate in the guts of D. magna in a manner similar to acid-treated nanotubes. The MWNTs were almost entirely eliminated by Daphnia fed algae during a 48 h elimination experiment, whereas elimination without feeding was typically minimal. Finally, PEI coatings increased MWNT toxicities, though this trend corresponded to the size of the PEI coatings, not their surface charges.     

Differential Effects of Betacyanin and Betaxanthin Pigments on Oxidative Stress and Inflammatory Response in Murine Macrophages

Scope: Betalain pigments are increasingly highlighted for their bioactive and anti-inflammatory properties, although research is lacking to demonstrate contributions of individual betalains. The work herein aimed to compare effects of four main betalains on inflammatory and cell-protective markers and to highlight potential structure-related relationships of the two main subgroups: betacyanins vs betaxanthins. Methods and results: Murine RAW 264.7 macrophages were stimulated with bacterial lipopolysaccharide following incubation with betacyanins (betanin, neobetanin) and betaxanthins (indicaxanthin, vulgaxanthin I) in concentrations from 1 to 100 µM. All betalains suppressed expression of pro-inflammatory markers IL-6, IL-1β, iNOS, and COX-2 with tendency for stronger effects of betacyanins compared to betaxanthins. In contrast, HO-1 and gGCS showed mixed and only moderate induction, while more emphasized effects were observed for betacyanins. While all betalains suppressed mRNA levels of NADPH oxidase 2 (NOX-2), a superoxide generating enzyme, only betacyanins were able to counteract hydrogen peroxide induced reactive oxygen species (ROS) generation, in alignment with their radical scavenging potential. Furthermore, betaxanthins exerted pro-oxidant properties, elevating ROS production beyond hydrogen peroxide stimulation. Conclusion: In summary, all betalains display anti-inflammatory properties, although only betacyanins demonstrate radical scavenging capacities, indicating potential differing responses under oxidative stress conditions, which requires further research.     

Determining genetic variability in the distribution of sensitivities to toxic stress among and within field populations of Daphnia magna

To extrapolate credibly from individuals in the laboratory to field populations, it is essential to account for genetic differences in susceptibility to toxic stress and thus incorporate genetic variability into ecological risk estimates. In this study, the distribution of sensitivities across two toxic chemicals among and within field populations of Daphnia magna were used to quantify genetic variability. The study employed 30 D. magna clones from three geographically separate European populations. The sensitivity of each population studied and its constituent clones was estimated in terms of the concentrations of lambda-cyhalothrin and cadmium impairing individual fitness by 10 and 50% (EC10-50). Results revealed that differences in tolerance among clones within populations were large when compared with differences between populations and that the genetic range of sensitivities to toxic stress within populations was log-normally distributed. Furthermore, reported variation in sensitivity values to toxic stress among different laboratory species, populations, and clones was similar to that observed among and within field populations of Daphnia. These results suggest that it is possible to estimate genetic variability by estimating the tolerance distribution of laboratory populations and clones and that extrapolation approaches currently used in ecological risk assessment should explicitly incorporate genetic variability in tolerance into risk estimates.     

小米抗氧化肽的纯化及其抑制H2O2诱导损伤的胰岛素瘤细胞氧化应激作用

本研究利用Sephadex G-25和DEAE-32对小米抗氧化肽进行纯化,利用醋酸纤维素薄膜电泳法测定小米抗氧化肽的纯度,以1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl,DPPH）自由基、超氧阴离子自由基、羟自由基清除实验考察纯化的小米抗氧化肽对自由基的清除能力。在细胞水平研究小米抗氧化肽对胰岛细胞的保护作用,利用H2O2进行大鼠胰岛素瘤细胞（INS-1）氧化应激造模,采用2’,7’-二氯二氢荧光素二乙酸酯荧光探针法检测细胞内活性氧（reactive oxygenspecies,ROS）水平,3-（4,5-二甲基噻唑-2）-2,5-二苯基四氮唑溴盐法检测细胞活力,采用流式细胞技术检测细胞凋亡率,采用实时荧光定量聚合酶链式反应检测抗氧化酶的表达水平。结果表明：经过Sephadex G-25和DEAE-32两次层析,小米抗氧化肽达到了电泳纯;50 μg/mL小米抗氧化肽对超氧阴离子自由基、羟自由基和DPPH自由基的清除率分别为（62.71±3.86）%、（73.56±4.51）%和（82.62±5.25）%;小米抗氧化肽能显著提升H2O2损伤后细胞活力,降低细胞内ROS水平,抑制H2O2诱导损伤的INS-1细胞的凋亡（P＜0.05）,其可能的机制与超氧化物歧化酶1、过氧化氢酶、谷胱甘肽巯基转移酶、醌氧化还原酶1等抗氧化酶系的表达上调有关。结论：小米抗氧化肽对H2O2诱导损伤的INS-1细胞氧化应激具有一定的保护作用。     

蓝莓酵素的体外抗氧化及对秀丽隐杆线虫的氧化应激保护作用

以大兴安岭野生蓝莓为原料,发酵制备蓝莓酵素,研究其发酵过程中总花青素、总酚和总黄酮含量变化,以及体外抗氧化能力变化情况,并以秀丽隐杆线虫为模型,初步探究其抗氧化的相关机制。结果表明:在发酵过程中,总花青素含量呈先上升后下降的变化趋势,于发酵第50 d时,达到了0.52 mg/mL,总酚和总黄酮含量总体呈现上升趋势,均于第300 d时达到最大值2.81、3.17 mg/mL;1, 1-二苯基-2-苦苯肼（1, 1-diphenyl-2-picrylhydrazyl,DPPH）自由基清除能力、还原力、氧自由基吸收能力（oxygen-radical absorbance capacity,ORAC）均呈现先快速增长后趋于平缓的变化趋势。蓝莓酵素能够延长秀丽隐杆线虫寿命,增强其在双氧水刺激下的氧化应激能力,提高超氧化物歧化酶（superoxide dismutase,SOD）、过氧化氢酶（catalase,CAT）和谷胱甘肽过氧化物酶（glutathione peroxidase,GSH-Px）等抗氧化酶的活力,并且降低线虫体内活性氧和丙二醛含量,该结果表明蓝莓酵素可能是通过提高抗氧化酶活力来减缓秀丽隐杆线虫的氧化损伤。     

Concurrent Separation of CO(2) and H(2)O from Air by a Temperature-Vacuum Swing Adsorption/Desorption Cycle

A temperature-vacuum swing (TVS) cyclic process is applied to an amine-functionalized nanofibrilated cellulose sorbent to concurrently extract CO(2) and water vapor from ambient air. The promoting effect of the relative humidity on the CO(2) capture capacity and on the amount of coadsorbed water is quantified. The measured specific CO(2) capacities range from 0.32 to 0.65 mmol/g, and the corresponding specific H(2)O capacities range from 0.87 to 4.76 mmol/g for adsorption temperatures varying between 10 and 30 °C and relative humidities varying between 20 and 80%. Desorption of CO(2) is achieved at 95 °C and 50 mbar(abs) without dilution by a purge gas, yielding a purity exceeding 94.4%. Sorbent stability and a closed mass balance for both H(2)O and CO(2) are demonstrated for ten consecutive adsorption-desorption cycles. The specific energy requirements of the TVS process based on the measured H(2)O and CO(2) capacities are estimated to be 12.5 kJ/mol(CO2) of mechanical (pumping) work and between 493 and 640 kJ/mol(CO2) of heat at below 100 °C, depending on the air relative humidity. For a targeted CO(2) capacity of 2 mmol/g, the heat requirement would be reduced to between 272 and 530 kJ/mol(CO2), depending strongly on the amount of coadsorbed water.     

Pu(V)O2+ adsorption and reduction by synthetic magnetite (Fe3O4)

Changes in aqueous- and solid-phase Pu oxidation state were monitored over time in magnetite (Fe3O4) suspensions containing 239Pu(V)-amended 0.01 M NaCl. Oxidation state distribution was determined by leaching of Pu into an aqueous phase followed by an ultrafiltration/solvent extraction technique. The capability of the technique to measure Pu oxidation state distribution was verified using 230Th(IV), 237Np(V), and 233U(VI) as oxidation state analogues. Reduction of Pu(V) was observed at all pH values (pH 3 to 8) and magnetite concentrations (10 to 100 m2 L(-1)). In the pH range 5 to 8, adsorption was a rate-limiting step, and reduction was mediated by the solid phase; at pH 3 reduction occurred in the aqueous phase. The overall reaction (describing both adsorption and reduction of Pu(V)) was found to be approximately first order with respect to the magnetite concentration and of order -0.34+/-0.02 with respect to the hydrogen ion concentration. Assuming first order dependence with respect to Pu, the overall reaction rate constant was calculated as k(rxn) = 4.79+/-0.62 x 10(-8) (m(-2) L)0.99(mol(-1) L)-0.34(s(-1)). The Pu(IV) solid-phase species became more stable over time.