自噬抑制剂3-MA上调H2O2损伤的PC12细胞氧化应激水平

为探究自噬抑制剂6-氨基-3-甲基腺嘌呤（3-methyladenine,3-MA）对损伤细胞氧化应激水平的影响,将3-MA作用于H2O2诱导的PC12细胞损伤模型,以自噬增强剂雷帕霉素（rapamycin,Rap）作为对照,探讨自噬与氧化应激的关系。测定线粒体的膜电位和细胞内的活性氧（reactive oxygen species, ROS）与丙二醛(malondialdehyde, MDA)含量,以及超氧化物歧化酶(superoxide dismutase,SOD)和过氧化氢酶(catalase,CAT)活性,评价损伤细胞的氧化应激状态。单丹(磺)酰戊二胺（monodansylcadaverine,MDC）染色,观察损伤细胞的自噬情况。蛋白质印迹分析损伤细胞中的自噬相关蛋白质LC3-II/LC3-I比值变化。实验结果显示：与正常组相比,H2O2损伤细胞的ROS水平上升到正常组的141%,MDA含量增加(P<0.001);CAT与SOD酶活力显著降低(P<0.001),差异均有统计学意义,证明损伤细胞氧化应激水平增加;MDC染色结果表明,H2O2组自噬明显增加。Western印迹结果表明,LC3-II/LC3-I值显著升高（P<0.05）;与损伤组相比,3-MA组MDC染色结果表明,自噬水平降低。Western印迹结果表明,LC3-II/LC3-I值下降;细胞内ROS水平升高,增加到正常组的208%。MDA含量增加(P<0.001),CAT、SOD酶活力降低(P<0.001)。综上结果表明,自噬抑制剂可增加H2O2诱导的PC12细胞损伤模型的氧化应激水平,增加细胞凋亡。     

Antioxidant and anti‐inflammatory effects of the monocarbonyl curcumin analogs B2BRBC and C66 in monocrotaline‐induced right ventricular hypertrophy

For 22 days after monocrotaline injection two groups of rats received either of the monocarbonyl curcumin analogs (2E,6E)‐2,6‐bis(2‐bromobenzylidene)cycloxehanone (B2BrBC) and (2E,6E)‐2,6‐bis([2‐tri?uoromethyl]benzylidene)cyclohexanone (C66), and their right ventricle parameters were compared to those from the control and the monocrotaline injected animals. B2BrBC and C66 treatments did not prevent the monocrotaline‐induced right ventricular hypertrophy but attenuated the changes in antioxidant enzyme activities and reduced inflammation. The level of thiol‐based nonenzymatic antioxidants did not change in the function of monocrotaline or curcumin analogs treatment. However, due to its stronger antioxidant properties, only B2BrBC treatment was effective in the reduction of monocrotaline‐associated lipid peroxidation. The obtained results suggest that increasing the levels of antioxidant enzymes may not be sufficient to reduce oxidative stress and chronic inflammation optimally and our current study supports the potential of compounds with more than one beneficial biological activity as a promising treatment against the progression of cardiac hypertrophy.     

Ready-to-use thermally stable mastermix pills for molecular biology applications

Rolling circle amplification (RCA), polymerase chain reaction (PCR), and loop-mediated isothermal amplification (LAMP), are powerful tools that can be used for gene manipulation, pathogen detection, and infectious disease diagnostics. However, these techniques require trained personnel, as the pipetting steps involved can lead to contamination and, consequently, erroneous results. Furthermore, many of the reagents used in molecular biology are thermally labile and must be kept within a cold-chain. In this article, we present a simple and cost-effective method that allows molecular biology reagents to be thermally stabilized into ready-to-use mastermixes via drying in pullulan and trehalose films. Our experimental results demonstrate that this method is capable of preserving the activity of RCA, PCR, LAMP, ligase, polynucleotide kinase, and Klenow fragment mastermixes for at least 3 months at ambient conditions. Thus, stabilizing reagents via drying in pullulan and trehalose film may allow for a drastic reduction in the number of pipetting steps and the elimination of the need for a cold chain. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2764, 2019.     

Exogenous Glycine Betaine Reduces Drought Damage by Mediating Osmotic Adjustment and Enhancing Antioxidant Defense in <i>Phoebe hunanensis</i>

Drought stress negatively impacts growth and physiological processes in plants. The foliar application of glycine betaine (GB) is an effective and low-cost approach to improve the drought tolerance of trees. This study examined the effect of exogenously applied GB on the cell membrane permeability, osmotic adjustment, and antioxidant enzyme activities of Phoebe hunanensis Hand.-Mazz under drought stress. Two levels (0 and 800 mL) of water irrigation were tested under different applied GB concentrations (0, 50, 100, and 200 mM). Drought stress decreased the relative water content by 58.5% while increased the electric conductivity, malondialdehyde, proline, soluble proteins, soluble sugars, and antioxidant enzyme activities (superoxide dismutase, catalase, peroxidase) by up to 62.9%, 42.4%, 87.0%, 19.1%, 60.5%, 68.3%, 71.7%, and 83.8%, respectively, on the 25^th day. The foliar application of GB, especially at 100 mM, increased the relative water content of P. hunanensis leaves under drought stress. The concentration of GB from 50 to 100 mM effectively alleviated the improvement of cell membrane permeability and inhibited the accumulation of membrane lipid peroxidation products. Under drought stress, the concentrations of proline, soluble proteins, and soluble sugars in the leaves of P. hunanensis increased as the applied GB concentration was increased and the water stress time was prolonged. Exogenously applied GB decreased oxidative stress and improved antioxidant enzyme activities as compared with treatments without GB application. Furthermore, the physiological and biochemical indexes of P. hunanensis showed a certain dose effect on exogenous GB concentration. These results suggest that GB helps maintain the drought tolerance of P. hunanensis.     

Effects of High-Temperature Stress on Photosynthetic Characteristics and Antioxidant Enzyme System of <i>Paeonia ostii</i>

Paeonia ostii is an economically important oil crop, which has been widely cultivated in the middle and lower reaches of the Yangtze River in China in recent years. Although P. ostii is highly adaptable to the environment, the prolonged high summer temperature in this region severely inhibits its growth, which adversely affects seed yield and quality. In this study, P. ostii plants were subjected to 20°C/15°C (day/night) and 40°C/35°C (day/night) temperatures for 15 days. The changes in physiological and biochemical indicators of P. ostii under high-temperature stress were initially investigated. The results showed that with the deepening of leaf etiolation, chlorophyll a and chlorophyll b concentration, carotenoid concentration, Soil Plant Analysis Development (SPAD) values and leaf relative water content decreased significantly, while both relative electrical conductivity (REC) and free proline concentration showed an upward trend. Meanwhile, the continuous accumulation of reactive oxygen species (ROS) in P. ostii plants, led to an increased activity of antioxidant enzymes including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX). Moreover, with the extension of the high-temperature treatment, the anatomical structures of P. ostii were destroyed, resulting in a decreased photochemical efficiency of the photosystem II (PSII) reaction center and photosynthesis was inhibited. Taken together, these results provide reference values for understanding the physiological response of P. ostii to high-temperature stress and establish a foundation for further research on the relevant underlying molecular mechanisms.

     

Biological Control of Root-Knot Nematode <i>Meloidogyne incognita</i> in <i>Psoralea corylifolia</i> Plant by Enhancing the Biocontrol Efficacy of <i>Trichoderma harzianum</i> Using Press Mud

Meloidogyne incognita is a plant pathogen causing root-knot disease and loss of crop yield. The present study aimed to use Trichoderma harzianum as a biocontrol agent against plant-parasitic nematodes and used press mud, which is a solid waste by-product of sugarcane, as a biocontrol agent and biofertilizer. Therefore, the combined application of T. harzianum and press mud may enhance nematode control and plant growth. Elemental analysis of press mud using scanning electron microscopy (SEM) integrated with an Energy Dispersive X-ray (EDX) analyzer revealed the presence of different elements such as C, O, Mg, Si, P, K, Ca, Cu and Zn. In addition, a greenhouse study was conducted to investigate the combined effects of press mud and T. harzianum on M. incognita reproduction and growth and the biochemical features of Psoralea corylifolia. The results showed that plant length, dry biomass, leaf area, the number of seeds per plant, chlorophyll a, chl b, carotenoid content, nitrate reductase, carbonic anhydrase, and nitrogen content were significantly increased (P ≤ 0.05) in the T2 plants (plants were treated with 100 g of press mud + 50 mL T. harzianum before one week of M. incognita inoculation), over inoculated plants (IC). Antioxidant enzyme activity of ascorbate peroxidase (APX), catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) in the foliage of P. corylifolia was significantly increased when plants were treated with press mud + T. harzianum. A significant reduction in the number of egg masses, nematode population, and root-knot index (RKI) was found in plants with T2 plants. These results suggest that the combined application of T. harzianum and press mud has the potential to control the M. incognita infection and can be used as an environmentally safe alternative to chemical nematicides and also help in the removal of sugarcane waste that causes environmental pollution.     

细菌降解双酚类化合物的分子机制研究进展

双酚类化合物(bisphenols,BPs)作为工业原料及药物和个人护理品的重要成分之一,在自然界中广泛分布。BPs作为类雌性激素造成的生态风险已成为全球备受关注的环境问题之一。研究人员使用不同方式分离得到菌株或菌群,尝试对BPs进行无害化降解,目前已取得了一些重要的研究进展。本文对近年来细菌降解BPs的相关研究进行了系统梳理,重点关注以双酚A(bisphenol A,BPA)为典型BPs的细菌降解,总结不同路径中的关键作用基因,讨论相同路径中酶的差异及作用方式,并分析其对BPA的降解效果。本文也简要总结了双酚S(bisphenolS,BPS)和其他BPs的细菌降解研究情况。通过总结讨论现有成果,分析细菌降解BPs中尚需深入研究的内容,探寻未来BPs细菌降解机理及应用的研究方向。