Patterns of peroxidative ethane emission from submerged rice seedlings indicate that damage from reactive oxygen species takes place during submergence and is not necessarily a post-anoxic phenomenon

Using ethane as a marker for peroxidative damage to membranes by reactive oxygen species (ROS) we examined the injury of rice seedlings during submergence in the dark. It is often expressed that membrane injury from ROS is a post-submergence phenomenon occurring when oxygen is re-introduced after submergence-induced anoxia. We found that ethane production, from rice seedlings submerged for 24–72 h, was stimulated to 4–37 nl gFW⁻¹, indicating underwater membrane peroxidation. When examined a week later the seedlings were damaged or had died. On de-submergence in air, ethane production rates rose sharply, but fell back to less than 0.1 nl gFW⁻¹ h⁻¹ after 2 h. We compared submergence-susceptible and submergence-tolerant cultivars, submergence starting in the morning (more damage) and in the afternoon (less damage) and investigated different submergence durations. The seedlings showed extensive fatality whenever total ethane emission exceeded about 15 nl gFW⁻¹. Smaller amounts of ethane emission were linked to less extensive injury to leaves. Partial oxygen shortage (O₂ levels <1%) imposed for 2 h in gas phase mixtures also stimulated ethane production. In contrast, seedlings under anaerobic gas phase conditions produced no ethane until re-aerated: then a small peak was observed followed by a low, steady ethane production. We conclude that damage during submergence is not associated with extensive anoxia. Instead, injury is linked to membrane peroxidation in seedlings that are partially oxygen deficient while submerged. On return to air, further peroxidation is suppressed within about 2 h indicating effective control of ROS production not evident during submergence itself.     

Microbial decolorization of spentwash: a review

Spentwash is one of the most complex and cumbersome wastewater with very high BOD, COD and other organic and inorganic toxic constituents. It is dark brown colored and difficult to treat by normal biological process such as activated sludge or anaerobic lagooning. The color is due to the presence of melanoidins, caramels and other polymers. These compounds have anti oxidant properties which render them toxic to microorganisms. Spentwash disposal into the environment is hazardous and has a considerable pollution potential. It affects the aesthetic merit. Its decolorization by physical or chemical methods have been investigated and were found unsuitable. In the recent past, increasing attention has been directed towards utilizing microbial activity for decolorization of spentwash. This review reveals various groups of microorganisms which have potential in spentwash decolorization. The role of enzymes in decolorization and the microbial degradation of individual compounds imparting color to spentwash are also discussed.     

木霉菌发酵羊胃容物产木聚糖酶的分离纯化及特性

目的:为城市屠宰场牛羊胃容物类的生物垃圾型可再生资源的潜在工业化开发应用(城市无害鲜生物垃圾变废为宝的低碳生物循环经济工程)提供了部分可靠科学依据.方法:M-112木霉菌固态发酵羊胃容物的粗酶提取液,经20～60%饱和度的硫酸铵粗分级分离、Sephadex G-25脱盐、Sephadex G-150到Sephadex G-100分子筛顺序纯化,通过蛋白质测定、酶活测定、SDS-PAGE和底物-PAGE电泳等.结果:制备到一种分子量约为64.7kDa的电泳纯木聚糖酶,其回收率为5.59%,纯化倍数10.43,比活力为253.36IU/mg.纯化出的木聚糖酶,经性质研究表明,其Km=11.20g/L,Vmax=0.70μmoL/min;最适温度为65℃,最适pH为6.0,该酶在中温条件下稳定性好,在酸性至弱碱性(pH 3.0～8.0)条件下稳定性好.结论:采用改良的凝胶色谱技术,首次纯化出木霉菌固态发酵羊胃容物所产的木聚糖酶.     

土壤-植物系统中稀土元素与氮磷养分的交互作用

土壤－植物系统中稀土元素与N,P养分交互作用属农田稀土安全性评价研究的前沿,土壤中稀土元素与N,P交互作用直接关系到稀土对农田土壤生产力的影响以及稀土对农作物的增产机理和生态环境安全性的评价,就土壤－植物系统中有关稀土元素与N,P交互作用的研究作简要综述,提出今后应加强作物根际,农田土壤表层以及植物体内稀土与N,P养分之间交互作用的研究。     

生态能质(eco-exergy)在水生生态系统建模和评价中的应用

生态能质(eco-exergy)是指系统从给定状态达到热力学平衡状态所做的功,可以度量生态系统的复杂生物化学组分及生态结构。系统具有的能质越大,有序化程度越高,稳定性也越强。生态能质和比生态能质(specific eco-exergy)指标能够评价水生生态系统健康状况,对水生生态系统演替阶段具有指示作用。本文阐述了生态能质的定义、生态学意义以及生态能质值和权重因子fi值的计算方法。对生态能质作为功能函数在水生生态系统结构动力学模型(structural dynamic models,SDMs)中以及作为生态指标在生态系统健康评价、生态恢复研究中的实际应用进行了总结。最后探讨了生态能质指标的局限性以及未来的发展。此外,文中建议将eco-exergy和specific eco-exergy统一翻译为生态能质和比生态能质。     

不同群落类型柔毛淫羊藿总黄酮和淫羊藿苷含量及其与土壤因子的关系

2009年8月,采用高效液相色谱法和紫外分光光度法测定了唐家河自然保护区次生落叶阔叶林红桦群落(群落Ⅰ)、常绿落叶阔叶混交林细叶青冈群落(群落Ⅱ)和常绿阔叶林油樟群落(群落Ⅲ)下生长的柔毛淫羊藿各器官的总黄酮和淫羊藿苷含量,分析其与土壤因子的关系结果表明：柔毛淫羊藿叶片中总黄酮和淫羊藿苷含量最高、茎中最低;群落Ⅰ的柔毛淫羊藿总黄酮和淫羊藿苷含量［(5.32±0.23)%和(0.47±0.05)%］均显著高于群落Ⅱ［(4.06±0.03)%和(0.32±0.01)%］和群落Ⅲ［(4.15±0.07)%和(0.28±0.09)%］;土壤氮含量和pH值对柔毛淫羊藿的总黄酮和淫羊藿苷含量影响较大,柔毛淫羊藿总黄酮和淫羊藿苷含量与土壤全氮和碱解氮呈显著负相关(P<0.05),与土壤pH值呈极显著正相关(P<0.01).土壤较低的氮供应水平和较高的土壤酸度可能使群落Ⅰ柔毛淫羊藿的总黄酮和淫羊藿苷含量增加.     

河南南湾水库浮游硅藻的种群结构与水质污染评价初步研究

通过对南湾水库6个采样点浮游硅藻分析,该水库硅藻61个种及种下分类单元。用多样性指数(H′)、均匀性指数(E)及硅藻优势种生态谱分析,对水质进行了初步评价。结果表明,南湾水库水质属清洁-轻污染等级。     

An Evaluation of the Impact of PD‐1 Pathway Blockade on Reproductive Safety of Therapeutic PD‐1 Inhibitors

This report discusses the principles of reproductive toxicity risk assessment for biopharmaceuticals blocking the PD‐1/programmed cell death ligand 1 (PD‐L1) pathway, which have been developed for the treatment of patients with advanced malignancies. The PD‐1/PD‐L1 pathway is a T‐cell co‐inhibitory pathway that normally maintains immune tolerance to self. Its role in pregnancy is to maintain immune tolerance to the fetal allograft. In cancer patients, this signaling pathway is hijacked by some neoplasms to avoid immune destruction. PD‐1/PD‐L1‐blocking agents enhance functional activity of the target lymphocytes to eventually cause immune rejection of the tumor. A therapeutic blockade of PD‐1/PD‐L1 pathway that occurs at full target engagement provides a unique challenge to address the risk to pregnancy because disruption of the same pathway may also reduce or abrogate maternal immune tolerance to the fetal alloantigens inherited through the father. Typically, nonclinical reproductive and developmental toxicity (DART) studies in animals (rats and rabbits) with clinical drug candidates are conducted to identify potential risk in humans and to determine exposure margin for the effects on reproduction as part of the risk assessment. However, for biopharmaceuticals for which the desired mechanism of action cannot be separated from potential deleterious effects to the fetus and when the only relevant toxicology species is nonhuman primate (NHP), the risk to reproduction can be predicted by a mechanism‐based assessment using data generated from murine surrogate models as supportive information without conducting DART in NHPs. Such an approach has been used in the evaluation of pregnancy risk of anti‐PD‐1 agent, pembrolizumab, and has been demonstrated as an important alternative to performing DART studies in NHPs     

Biodiesel production from waste cooking oil: 2. Economic assessment and sensitivity analysis

The economic feasibilities of four continuous processes to produce biodiesel, including both alkali- and acid-catalyzed processes, using waste cooking oil and the ‘standard’ process using virgin vegetable oil as the raw material, were assessed. Although the alkali-catalyzed process using virgin vegetable oil had the lowest fixed capital cost, the acid-catalyzed process using waste cooking oil was more economically feasible overall, providing a lower total manufacturing cost, a more attractive after-tax rate of return and a lower biodiesel break-even price. On the basis of these economic calculations, sensitivity analyses for these processes were carried out. Plant capacity and prices of feedstock oils and biodiesel were found to be the most significant factors affecting the economic viability of biodiesel manufacture.