Structural determinants of multimerization and dissociation in 2-Cys peroxiredoxin chaperone function

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Drought,high temperature,and their combination affect ultrastructure of chloroplasts and mitochondria in wheat (Triticum aestivum L.) leaves

Plants experience a number of limiting factors, as drought and heat, which are often coinciding stress factors in natural environment. This study evaluated the changes in mesophyll cell ultrastructure in the leaves of two varieties of winter wheat (Triticum aestivum L.), differing in their drought tolerance, under individual or combined drought and heat treatment. Although the individual stress factors affected leaf ultrastructure, the damaging effect of the combined drought and heat was more pronounced and manifested certain differences between genotypes. Chloroplasts and mitochondria were affected in a variety-specific manner under all adverse treatments. The organelles of the drought-tolerant Katya were better preserved than those in the sensitive variety Sadovo. Leaf ultrastructure can be considered as one of the important characteristics in the evaluation of the drought susceptibility of different wheat varieties.     

我国三大城市群地区城市和农业用地地表热环境效应对比研究

以大中小城市协同发展为特征的城市群已成为我国城市化发展的主要形式，城市化和农业作为城市群地区最主要的土地利用活动，其气候效应是国际研究的热点。然而过去研究多关注大城市的热岛效应，对更为普遍的农业活动以及中小城市城市化的气候效应认识十分薄弱。基于MODIS地表温度数据，以自然林地为参照，提出了一种可逐像元估算土地利用地表热环境效应的新方法，进而对比分析了我国三大城市群地区（京津冀、长三角和珠三角）城市和农业用地地表热环境效应及其驱动因子差异。结果表明各城市群白天城市热岛效应明显，地级以上城市年平均热岛强度达3.2℃以上，但最强热岛均未发生在核心城市。夜晚热岛效应明显减弱，京津冀和长三角部分城市甚至出现冷岛效应。农业用地在白天亦表现出明显的增温效应，特别是在京津冀地区，而在夜晚除珠三角城市群外，降温效应明显，京津冀和长三角地区平均降温2.3℃和0.7℃。虽然城市用地平均增温强度大于农业用地，但农业用地因面积优势对区域温度变化起控制作用。白天城市和农业用地整体导致各城市群温度明显增加，京津冀增温最高（4.0℃），夜晚二者导致长三角和京津冀地区平均温度降低。研究还发现各城市群城市和农业用地地表热环境效应时空异质性极大，主要受植被、地表反照率、气候背景和人口密度控制。本文对制定缓解气候变化的土地利用策略具有重要的指导意义。     

A study on thermal damage during hyperthermia treatment based on DPL model for multilayer tissues using finite element Legendre wavelet Galerkin approach

Hyperthermia is a process that uses heat from the spatial heat source to kill cancerous cells without damaging the surrounding healthy tissues. Efficacy of hyperthermia technique is related to achieve temperature at the infected cells during the treatment process. A mathematical model on heat transfer in multilayer tissues in finite domain is proposed to predict the control temperature profile at hyperthermia position. The treatment technique uses dual-phase-lag model of heat transfer in multilayer tissues with modified Gaussian distribution heat source subjected to the most generalized boundary condition and interface at the adjacent layers. The complete dual-phase-lag model of bioheat transfer is solved using finite element Legendre wavelet Galerkin approach. The present solution has been verified with exact solution in a specific case and provides a good accuracy. The effect of the variability of different parameters such as lagging times, external heat source, metabolic heat source and the most generalized boundary condition on temperature profile in multilayer tissues is analyzed and also discussed the effective approach of hyperthermia treatment. Furthermore, we studied the modified thermal damage model with regeneration of healthy tissues as well. For viewpoint of thermal damage, the least thermal damage has been observed in boundary condition of second kind. The article concludes with a discussion of better opportunities for future clinical application of hyperthermia treatment.     

Data acquisition in thermal physiology: Measurements of shivering

1. 1.|Simple electronics for measurement of shivering, which include direct and mean rectified EMG (U_mrv), are suggested.

2. 2.|A software system (LabGraph) for measurement and analysis is described.

3. 3.|Three different electrode designs were tested with the system by recording electromyography (EMG) from m. iliotibialis with subdermal, intramuscular and safety pin electrodes in bantam hens exposed to cold eggs. The signal characteristics of EMG are discussed in relation to electrode design and signal processing.

4. 4.|A method for normalizing EMG activity within an experiment to units of heat production is presented and was tested successfully in bantam hens.

Potential Interaction of Plasmodium falciparum Hsp60 and Calpain

After invasion of red blood cells, malaria matures within the cell by degrading hemoglobin avidly. For enormous protein breakdown in trophozoite stage, many efficient and ordered proteolysis networks have been postulated and exploited. In this study, a potential interaction of a 60-kDa Plasmodium falciparum (Pf)-heat shock protein (Hsp60) and Pf-calpain, a cysteine protease, was explored. Pf-infected RBC was isolated and the endogenous Pf-Hsp60 and Pf-calpain were determined by western blot analysis and similar antigenicity of GroEL and Pf-Hsp60 was determined with anti-Pf-Hsp60. Potential interaction of Pf-calpain and Pf-Hsp60 was determined by immunoprecipitation and immunofluorescence assay. Mizoribine, a well-known inhibitor of Hsp60, attenuated both Pf-calpain enzyme activity as well as P. falciparum growth. The presented data suggest that the Pf-Hsp60 may function on Pf-calpain in a part of networks during malaria growth.     

Heat shock temperature acclimation of normal secretory protein synthesis in barley aleurone cells

Exposure of barley (Hordeum vulgare L. cv. Himalaya) aleurone layers to 40°C for a period of 3 h results in the selective suppression of the synthesis and secretion of hydrolytic enzymes; other normal cellular protein synthesis continues during heat shock. This suppression is correlated with secretory protein mRNA destabilization and the dissociation of stacked ER lamellae during heat shock (Belanger et al. 1986, Proceedings of the National Academy of Sciences USA 83, pp. 1354–1358). In this report we examined the effect of exposure to extended periods of heat shock. If exposure to 40°C was continued for a period of 18 h, the synthesis of α-amylase, the predominant secreted hydrolase, resumed. This was accompanied by increased α-amylase mRNA levels and the reformation of ER lamellae. Though initial exposure (3 h) to 40°C reduced protein secretion to ～10% of that observed in aleurone cells maintained at 25°C, exposure for prolonged periods (16–20 h) permitted the resumption of protein secretion to ～66% of non-heat-shocked control levels. The resumption of normal secretory protein synthesis during prolonged exposure to 40°C was correlated with an increase in the incorporation of [¹⁴C]glycerol into phosphatidylcholine and an increase in the ratio of saturated to unsaturated fatty acids in lipids isolated from ER membrane preparations. Increased fatty acid saturation has been demonstrated to enhance thermostability in biological membranes, and such changes in membrane composition may be important to the recovery of secretory protein synthesis at the ER.     

四川省不同天然种群珙桐叶片解剖结构与其耐热性的关系

以四川省15个珙桐种群为试材,采用石蜡切片法、NaClO法观察叶片16项解剖结构,应用变异系数、聚类分析、相关性分析对叶片解剖结构进行筛选,利用隶属函数法对不同种群的耐热性进行综合评价,以期了解珙桐应对热胁迫的生理变化机制,为野生珙桐资源的保护及园林应用提供参考。结果表明：珙桐叶片为异面叶,气孔主要分布于下表皮。16项解剖结构指标在不同种群间达到极显著差异水平;栅海比、栅栏组织厚度、气孔密度、下表皮角质厚度、主脉凸起度、上表皮角质层厚度、下表皮细胞厚度是影响珙桐耐热性的主要解剖结构指标,叶厚度、海绵组织厚度、主脉厚度、上表皮细胞厚度、主脉维管束厚度、气孔长度、气孔宽度、叶片结构紧密度、叶片结构疏松度与耐热性关系不大;15个珙桐种群耐热性存在一定差异,其强弱顺序为：汉源 > 筠连 > 雷波 > 沐川 > 屏山 > 荥经 > 天全 > 美姑 > 平武 > 碧峰峡 > 北川 > 洪雅 > 宝兴 > 大邑 > 邛崃;15个种群耐热性大致分为4类：汉源种群为耐热型,筠连、雷波、沐川等3个种群为中度耐热型,屏山、荥经、天全、美姑、平武、碧峰峡、北川为低耐热型,洪雅、宝兴、雷波、邛崃等4个种群为不耐热型。