A strategy for high cell density culture of heterotrophic microalgae with inhibitory substrates

Substrate inhibition is one of the major problems preventing high cell densities of microalgae in heterotrophic culture, so the possibility of overcoming the problem by various culture techniques was examined. It was found that perfusion culture may be the most appropriate technique for high cell densities in heterotrophic culture using inhibitory substrates. An experimental example in which a hollow fibre cell recycle system (HFCRS) was employed to achieve high cell densities of Chlamydomonas reinhardtii on acetate under heterotrophic conditions of growth was demonstrated. The cell density in the HFCRS was much higher than that reported in the literature for this species.     

The Neural Basis of Responsibility Attribution in Decision-Making

Social responsibility links personal behavior with societal expectations and plays a key role in affecting an agent’s emotional state following a decision. However, the neural basis of responsibility attribution remains unclear. In two previous event-related brain potential (ERP) studies we found that personal responsibility modulated outcome evaluation in gambling tasks. Here we conducted a functional magnetic resonance imaging (fMRI) study to identify particular brain regions that mediate responsibility attribution. In a context involving team cooperation, participants completed a task with their teammates and on each trial received feedback about team success and individual success sequentially. We found that brain activity differed between conditions involving team success vs. team failure. Further, different brain regions were associated with reinforcement of behavior by social praise vs. monetary reward. Specifically, right temporoparietal junction (RTPJ) was associated with social pride whereas dorsal striatum and dorsal anterior cingulate cortex (ACC) were related to reinforcement of behaviors leading to personal gain. The present study provides evidence that the RTPJ is an important region for determining whether self-generated behaviors are deserving of praise in a social context.     

侗族九个红细胞血型系统和ABH分泌型的分布

报道了广西侗族的ABO、MNSs、Rhesus、Duffy、Kidd、P、Diego、Lewis和Xg等九种红细胞血型系统和ABH唾液分泌型的分布。共调查了201名父母均系侗族而彼此无血缘的学生,其中男116名,女85名。结果表明,广西侗族中ABO系统的r基因(0.6286)、MN系统的m基因(0.6294)、Duffy系统的Fy~a基因(0.9651)、Kidd系统的JK~a基因(0.4628)和Rhesus系统的CDe染色体(0.7532)等频率都很高,ABO系统的q基因(0.1672)、P系统的P_1基因(0.1333)和Lewis系统的Le~a基因(0.3232)等频率较低。MNSs系统的S基因(0.0124)频率很低,而MS染色体连锁率却为零。Xg系统的Xg~a基因频率(0.3746)与汉族和维吾尔族一样,处于低水平。Lewis系统的Le(a )表型者中发现八例是ABH唾液分泌型,但分泌的物质不是A便是B,而分泌H物质的唾液分泌型者全部都是Le(a-)型。六个民族间遗传距离分析表明,侗族与壮族在血缘上最近,其次是与朝鲜族、蒙古族、汉族相近,而与维吾尔族最远。     

DNA-dependent RNA polymerases from Schneider 2-L cells of Drosophila. I. Preliminary characterization

The DNA-dependent RNA polymerases of Schneider 2-L cells of Drosophila melanogaster are described. These cells contain five readily detectable forms of this enzyme, polymerases I_a, I_b, III_a, II, and III_b, which elute from DEAE-Sephadex at 0.08, 0.12, 0.15, 0.20, and 0.22 m ammonium sulfate, respectively. RNA polymerases III_a and III_b, which each constitute about 5–10% of the total RNA polymerase activity in Drosophila embryos, are found to constitute 30 and 10%, respectively, of the total polymerase activity in cultured cells. The two form III polymerases are further characterized by in vitro response to divalent cations and ionic strength, template utilization, and sensitivity to -amanitin. Verification of the class III designation of these two polymerases is provided by their sensitivity to only very high levels of -amanitin (50% inhibition at approximately 800 µg/ml), their 10-fold greater activity on poly[d(A–T)], and their elution from DEAE-cellulose at lower ionic strengths than from DEAE-Sephadex.This work was supported by the Natural Sciences and Engineering Research Council.     

植物蛋白质S-亚硝基化修饰的检测与分析

S-亚硝基化是一种重要的蛋白质翻译后修饰方式, 是指一氧化氮(NO)基团共价连接至靶蛋白特定半胱氨酸残基的自由巯基, 从而形成S-亚硝基硫醇(SNO)的过程。S-亚硝基化修饰广泛存在于各有机体中, 通过改变蛋白质生化活性、稳定性、亚细胞定位以及蛋白质-蛋白质相互作用等机制而调控不同的生物学过程或信号通路。在蛋白质S-亚硝基化检测分析方法中, 最为广泛使用的是生物素转化法(biotin switch assay), 其基本原理是首先封闭未被修饰的自由巯基, 进而将被修饰的SNO基团特异地还原为自由巯基并使用生物素将其特异标记。被生物素标记的半胱氨酸残基(即被修饰位点)可进一步通过蛋白质免疫印迹和/或质谱等方法进行检测分析。该文详细描述了植物蛋白质样品的体内和体外生物素转化法的实验流程, 并对实验过程中的注意事项进行了讨论。     

机械损伤对9种水生植物叶片的影响

水生植物叶片的功能性状特征与陆生植物有所不同,同时叶脉类型也显著影响叶片的功能性状。本研究选取9种具有不同叶脉类型的水生植物,通过对叶脉进行直接损伤,分析叶片性状（形态、色素含量和叶绿素荧光指标）在叶脉受损后的变化程度与叶脉类型的关系。结果显示：具有平行脉的3种水生植物对叶脉损伤具有较强的耐受性;具羽状脉的4种植物主脉受损后显著抑制叶片生长,而侧脉受损的影响在不同物种间有所不同,具有物种特异性。本研究可为大型湖泊水生植物修复的水生物种筛选提供参考。