Estimation of Cellobiohydrolase I Activity by Numerical Differentiation of Dynamic Ultraviolet Spectroscopy

1,4-β-D-glucan cellobiohydrolase I (CBH I),p-nitrophenyl β-D-cellobioside,p-nitrophenol andcellobiose show distinct ultraviolet spectra,allowing the design of an assay to track the dynamic process ofp-nitrophenyl β-D-cellobioside hydrolysis by CBH I.Based on the linear relationship between p-nitrophenolformation in the hydrolysate and its first derivative absorption Curve of AUC340_400_(nm)(area under the curve),a new sensitive assay for the determination of CBH I activity was developed.The dynamic parameters ofcatalysis reaction,such as Vm and k_(cat),can all be derived from this result.The influence of β-glucosidase andendoglucanase in crude enzyme sample on the assay was discussed in detail.This approach is useful foraccurate determination of the activity of CBHs.     

氮沉降背景下土壤微生物对入侵植物乌桕叶绿素荧光特征的影响

植物入侵会造成入侵地生态系统功能和稳定性的破坏。与原产地种源相比,入侵种源植物在生理学特性方面有所不同,使其在资源利用和抵抗环境胁迫具有较强的竞争优势。叶绿素荧光特性与植物光合作用效率密切相关,对植物生长具有重要作用。氮沉降加剧是全球变化的一个重要因子,土壤微生物对植物吸收利用土壤养分至关重要。通过施用细菌抑制剂（链霉素）和真菌抑制剂（扑海因）选择性抑制的土壤微生物活性,开展乌桕盆栽实验,在模拟氮沉降背景下,研究不同微生物群落如何影响入侵乌桕叶绿素荧光特性,有助于理解入侵植物的进化特征和入侵机制,为有效防控入侵植物并降低其对生态系统危害提供理论依据。以原产地地和入侵地两个种源乌桕（Triadica sebifera）为研究对象,在氮沉降条件下,通过调控土壤细菌和真菌,探讨两个种源乌桕叶绿素荧光参数差异。结果显示：氮沉降显著增加乌桕相对叶绿素含量（SPAD）、光系统II的最大量子产率（F_v/F_m）、非光化学猝灭（NPQ）和半饱和光强（I_k）。入侵种源乌桕比原产地具有较低SPAD。氮沉降与细菌抑制剂共同作用显著增强了F_v/F_m、NPQ和I_k,显著减弱了光能利用率（α）和SPAD。细菌抑制剂减缓了本地种源乌桕α,真菌抑制剂促进本地种源乌桕I_k,抑制入侵种源乌桕I_k,细菌和真菌抑制剂可显著降低原产地乌桕α。氮沉降与生物抑制剂可显著作用于乌桕叶片SPAD。氮沉降、土壤微生物和不同乌桕种源可共同作用于光系统Ⅱ实际光合量子产率Y（Ⅱ）,α和潜在最大相对电子传递速率（ETR_max）。因此,氮沉降与生物抑制剂对乌桕叶绿素荧光特性具有协同作用,入侵种源乌桕对土壤微生物控制的响应不明显,在微生物控制条件下依然具有较强的适应能力,因而具有较强的入侵能力。     

新型声学造影剂在常规诊断超声频率下对在 体肾脏及离体培养细胞影响的研究

目的：评价新型超声造影剂在常规诊断超声频率下对组织细胞结构的影响。资料和方法：体外培养的人近曲小管上皮细胞分为造影剂无超声照射组,单纯超声照射组,MI 1．5,造影剂加超声照射组。MI 0．28,造影剂加超声照射组,MI 1．5。超声照射时间为10分钟。实验完后用2.5％的戊二醛固定4小时,送电镜室做扫描电镜。正常免肾经耳缘静脉按0．02ml／kg团注脂氟显（新桥医院超声科实验室自制）,用6MHz的超声频率照射,MI 0．28。照射10分钟。活体取肾皮质。放入3．0％的戊二醛溶液中固定,送电镜室做投射电镜。结果：离体培养的人近端小管上皮细胞单纯超声照射、单纯加造影剂、造影剂加超声照射MI 0．28和MI 1．5时扫描电镜观察细胞形态无改变,细胞表面未见异常。透射电镜观察免肾小囊腔和肾小管上皮细胞超微结构未见特异性政变。结论：新型脂质体声学造影剂在诊断剂量超声照射下不会对组织细胞结构产生影响。新型脂质体声学造影剂在诊断剂量下是安全的。     

Plasma Adiponectin Levels Correlate Positively with an Increasing Number of Components of Frailty in Male Elders

Objective

Frailty is an important geriatric syndrome. Adiponectin is an important adipokine that regulates energy homeostasis. The aim of this study is to investigate the relationship between plasma adiponectin levels and frailty in elders.

Methods

The demographic data, body weight, metabolic and inflammatory parameters, including plasma glucose, total cholesterol, triglyceride, tumor necrosis factor alpha (TNF-α), c-reactive protein (CRP) and adiponectin levels, were assessed. The frailty score was assessed using the Fried Frailty Index (FFI).

Results

The mean (SD) age of the 168 participants [83 (49.4%) men and 85 (50.6%) women] was 76.86 (6.10) years. Judged by the FFI score, 42 (25%) elders were robust, 92 (54.7%) were pre-frail, and 34 (20.3%) were frail. The mean body mass index was 25.19 (3.42) kg/m². The log-transformed mean (SD) plasma adiponectin (µg/mL) level was 1.00 (0.26). The log-transformed mean plasma adiponectin (µg/mL) levels were 0.93 (0.23) in the robust elders, 1.00 (0.27) in the pre-frail elders, and 1.10 (0.22) in the frail elders, and the differences between these values were statistically significant (p  = 0.012). Further analysis showed that plasma adiponectin levels rose progressively with an increasing number of components of frailty in all participants as a whole (p for trend  = 0.024) and males (p for trend  = 0.037), but not in females (p for trend  = 0.223).

Conclusion

Plasma adiponectin levels correlate positively with an increasing number of components of frailty in male elders. The difference between the sexes suggests that certain sex-specific mechanisms may exist to affect the association between adiponectin levels and frailty.     

神经系统中的一氧化氮

一氧化氮(NO)是一种广泛存在的独特的生物信使因子和效应因子.NO参与脑内许多生理功能和病理生理过程.NO调节神经递质释放和脑血流,参与神经发育和基因表达调控.NO可能作为一种逆行信使物质参与海马的长时程突触传递增强和小脑的长时程突触传递抑制.过多的NO则具有神经毒性并与许多神经系统疾病有关.     

剪切应力诱导血小板聚集

剪切应力诱导血小板聚集（shear-induced platelet aggregation, SIPA）是指在高剪切流场诱导下血小板表面的膜糖蛋白（GPⅠb/Ⅸ/Ⅴ和GPⅡb/Ⅲa）与血浆中的von Willebrand因子（vWF）相结合,介导血小板的活化、黏附和聚集,是动脉血栓的重要成因.SIPA还需要Ca2+,ADP/ATP等生化因素的参与,因而SIPA现象是生化因素和力学因素偶合作用的结果.细胞外Ca2+是高剪切应力诱导血小板发生聚集的必需条件,Ca2+的跨膜内流引起细胞骨架结构的改变和GPⅡb/Ⅲa的活化.近来对ADP/ATP位于血小板膜上的P2受体的研究表明,P2受体与细胞内Ca2+协同作用通过多种生化途径调控血小板的活化过程在SIPA的信号传导中起着关键的作用.从力学环境与生化反应的偶合关系入手研究SIPA现象的触发机制,深入研究SIPA现象中的信号转导通路是今后的研究热点之一.     

组蛋白磷酸化参与学习记忆调控的分子机制

组蛋白磷酸化是组蛋白翻译后修饰诸多方式中的一种,属于表观遗传学的范畴,在DNA损伤修复、细胞分裂等过程中发挥作用.近年来研究表明,组蛋白磷酸化在学习记忆等认知功能中也发挥重要的调节作用.本文主要就组蛋白磷酸化在学习记忆中的作用,及其上游信号通路、下游转录调控机制做一综述,旨在为认知功能障碍相关疾病提供新的理论基础和治疗靶点.     

增强UV-B辐照对小麦幼苗叶肉细胞内Ca2＋水平的研究

以小麦（Triticum aestivum）幼苗叶片为材料,利用提取原生质体方法在小麦幼苗叶肉细胞中成功地装载了钙离子荧光指示剂fluo-3/AM,采用激光共聚焦显微技术检测了增强UV-B辐射后小麦幼苗叶肉细胞内游离钙离子荧光强度的分布,并对[Ca2＋];进行了测定.结果显示,对照组细胞内钙离子荧光分布较均匀,主要分布于紧贴质膜处和核周围,UV-B辐射组钙离子荧光与对照组分布相似,但其原生质体表面不如对照组平滑;同时发现增强UV-B辐射组细胞内钙离子荧光强度值较对照组高,说明增强UV-B辐射组小麦幼苗叶肉细胞维持较高浓度的钙离子水平.这些变化表明Ca2＋信号有可能以一定的方式参与了小麦响应UV-B辐射胁迫的过程.     

Autoimmunity-related demyelination in infection by Japanese encephalitis virus

Japanese encephalitis (JE) virus is the most common cause of epidemic viral encephalitis in the world. The virus mainly infects neuronal cells and causes an inflammatory response after invasion of the parenchyma of the brain. The death of neurons is frequently observed, in which demyelinated axons are commonly seen. The mechanism that accounts for the occurrence of demyelination is ambiguous thus far. With a mouse model, the present study showed that myelin-specific antibodies appeared in sera, particularly in those mice with evident symptoms. Meanwhile, specific T cells proliferating in response to stimulation by myelin basic protein (MBP) was also shown in these mice. Taken together, our results suggest that autoimmunity may play an important role in the destruction of components, e.g., MBP, of axon-surrounding myelin, resulting in demyelination in the mouse brain after infection with the JE virus.     

应用体内诱导抗原技术筛选结核分枝杆菌体内表达基因

为寻找新型抗结核药物靶标 ,采用体内诱导抗原技术筛选结核分枝杆菌的体内诱导基因。首先构建了结核分枝杆菌基因组质粒表达文库 ,库容量为 1 0 2× 1 0 5CFU。再用经过结核分枝杆菌和大肠杆菌的裂解产物吸附过的结核病人血清 ,通过原位免疫印迹来筛选基因组表达文库 ,共获得 1 6个阳性克隆。对阳性克隆进行测序和生物信息学分析 ,发现该 1 6个阳性克隆可能包含 2 2个开放阅读框 (ORF)。按照功能将其分为 7类基因 :脂类代谢 2个、信号途径 5个、PE/PPE蛋白家族 2个、中间产物与能量代谢 6个、细胞壁与细胞处理 1个、假想蛋白 4个和与牛型分枝杆菌定向进化同源的 2个 ,其中部分基因可能与毒力相关 ,可以作为候选药物靶标