水杉的未尽事宜

主要阐述与水杉有关的三个问题：首先是水杉研究的教训,特别是从编辑、作者和学者的角度;其次讨论水杉研究的不明之处,包括王战的标本是如何到达吴仲伦之手而转送给郑万钧的,薛纪如和华敬灿谁先打听到小河的原产地,三木茂的论文是如何到达中国而胡先辅又是如何得到的;并讨论了水杉的栽培及栽培品种的注册以及水杉原产地的资源保护、旅游开发及宣传;最后建议成立水杉博物馆,编写中国植物采集史,编写东亚植物分类学文献目录新续编。     

When a motor goes bad: a kinesin regulates neuronal survival

In this issue of Cell, Midorikawa et al. (2006) demonstrate that the kinesin superfamily member KIF4, a microtubule-based molecular motor, regulates the survival of electrically active neurons in the developing brain by modulating the function of poly(ADP-ribose) polymerase-1 in an unexpected way.     

诺卡氏菌形放线菌β-甘露聚糖酶的水解特性

诺卡氏菌形放线菌（Nocardioform actinomycetes）NA3-540产生的β-甘露聚糖酶（ManNA）能不同程度地水解槐豆胶、瓜胶、田菁胶和魔芋胶等甘露多聚糖为组分的植物胶,生成系列甘露寡糖;该酶只轻微地水解香豆胶,不能水解β-甘露聚糖、黄原胶、海藻胶;ManNA对槐豆胶、瓜胶和魔芋胶多糖的Km值和Vmax分别为1．75、6．13、3．9mg／mL和2485、1303、853μmol／（min／mg）,表明槐豆胶是该酶的理想水解底物。ManNA水解几种植物胶的明显差异,表明甘露聚糖的糖链组成和空间结构明显地影响着β-甘露聚糖酶的水解活性。     

Thermodynamic analysis of catalysis by the dihydroorotases from hamster and Bacillus caldolyticus, as compared with the uncatalyzed reaction

Dihydroorotase (DHOase, EC 3.5.2.3) from the extreme thermophile Bacillus caldolyticus has been subcloned, sequenced, expressed, and purified as a monomer. The catalytic properties of this thermophilic DHOase have been compared with another type I enzyme, the DHOase domain from hamster, to investigate how the thermophilic enzyme is adapted to higher temperatures. B. caldolyticus DHOase has higher Vmax and Ks values than hamster DHOase at the same temperature. The thermodynamic parameters for the binding of L-dihydroorotate were determined at 25 degrees C for hamster DHOase (deltaG = -6.9 kcal/mol, deltaH = -11.5 kcal/mol, TdeltaS = -4.6 kcal/mol) and B. caldolyticus DHOase (deltaG = -5.6 kcal/mol, deltaH = -4.2 kcal/mol, TdeltaS = +1.4 kcal/mol). The smaller enthalpy release and positive entropy for thermophilic DHOase are indicative of a weakly interacting Michaelis complex. Hamster DHOase has an enthalpy of activation of 12.3 kcal/mol, similar to the release of enthalpy upon substrate binding, rendering the kcat/Ks value almost temperature independent. B. caldolyticus DHOase shows a decrease in the enthalpy of activation from 12.2 kcal/mol at temperatures from 30 to 50 degrees C to 5.3 kcal/mol for temperatures of 50-70 degrees C. Vibrational energy at higher temperatures may facilitate the transition ES --> ES(double dagger), making kcat/Ks almost temperature independent. The pseudo-first-order rate constant for water attack on L-dihydroorotate, based on experiments at elevated temperature, is 3.2 x 10(-11) s(-1) at 25 degrees C, with deltaH(double dagger) = 24.7 kcal/mol and TdeltaS(double dagger) = -6.9 kcal/mol. Thus, hamster DHOase enhances the rate of substrate hydrolysis by a factor of 1.6 x 10(14), achieving this rate enhancement almost entirely by lowering the enthalpy of activation (delta deltaH(double dagger) = -19.5 kcal/mol). Both the rate enhancement and transition state affinity of hamster DHOase increase steeply with decreasing temperature, consistent with the development of H-bonds and electrostatic interactions in the transition state that were not present in the enzyme-substrate complex in the ground state.     

Type 2 diabetes-an introduction to the development and use of animal models

Although the epidemiology of type 2 diabetes (T2D) has been well described, there is much about the disease that remains unclear. For example, lifestyle factors-including increased body weight with visceral fat deposition and insufficient physical activity-are thought to be primary contributors to the adverse changes in the metabolism of muscle and fat cells that comprise the first stage of the disease. However, the precise mechanisms underlying these initial alterations are incompletely understood. Other, less obvious questions relate to the presence of sex differences in the development and health consequences of T2D, the etiological role of the central nervous system ("stress"), and the potential evolutionary origins of T2D susceptibility. Some of these issues can be resolved by further study of human populations. However, many questions can be answered only through the kinds of controlled prospective studies that are conducted with appropriate animal models. The use of such models can be an invaluable part of an overall strategy designed to elucidate the mechanisms underlying the development of T2D, understand the natural history of the disease, identify targets for therapy, and evaluate interventions. Current evidence indicates that no single animal model replicates the development of human T2D in all of its details. Nonetheless, the existing models (e.g., naturally occurring and genetically modified rodents, cats, pigs, and nonhuman primates) offer researchers a rich array of opportunities to investigate the myriad complexities of T2D. The individual contributions comprising this issue of ILAR Journal review the research that has been conducted on many of these animals.     

Medical therapy for benign prostatic hyperplasia: new terminology, new concepts, better choices

This article discusses 3 areas of medical therapy for benign prostatic hyperplasia (BPH) that are undergoing extensive research and evaluation: 1) the use of muscarinic receptor antagonists to treat lower urinary tract symptoms (LUTS) in men with BPH; 2) the definition of an "enlarged prostate"; and 3) sexual function and LUTS. Fears of worsening obstructive symptoms or causing acute urinary retention often keep practitioners from prescribing muscarinic receptor antagonists to men who might have concomitant bladder outlet obstruction; a multicenter, multinational, double-blind study showed that tolterodine is safe for men with low postvoid residual volumes. Most urologists accept that a prostate volume of more than 40 mL is consistent with an enlarged prostate; there is more debate regarding prostate volumes of 30 to 40 mL. Recently presented data suggest that combination medical therapy might be effective for men having prostates with volumes of more than 25 mL. The association between voiding and sexual function has been increasingly recognized and investigated, and there seem to be common pathophysiologic mechanisms governing both conditions. Targeted treatment algorithms addressing both conditions seem warranted.     

东亚飞蝗羧酸酯酶基因的克隆和原核表达

羧酸酯酶是昆虫体内重要的代谢解毒酶系,其主要功能是水解和结合内源性和外源性含有酯键的有毒物质,减缓其到达靶标部位的时间。东亚飞蝗Locusta migratoria manilensis(Meyen)是我国重要的农业害虫,对其羧酸酯酶基因克隆和表达有助于深入探索杀虫剂代谢毒理机制。本研究首先对羧酸酯酶基因(CarE4)进行了克隆,并将其插入到pCold TF DNA Vector中,在大肠杆菌中进行了原核表达,最后用疏水层析和离子交换层析方法对目的蛋白进行了纯化。本文成功建立了羧酸酯酶蛋白原核表达和纯化技术体系,为进一步研究东亚飞蝗羧酸酯酶的生理功能、结构特点和作用原理提供了基础资料。     

Recent progress in research on insect histone deacetylases (HDACs)

组蛋白乙酰化修饰是一种重要的蛋白质翻译后修饰方式,由组蛋白乙酰基转移酶HATs和组蛋白去乙酰化酶HDACs共同调节.昆虫HDACs蛋白家族根据其同源性和结构的不同共分为4类,各昆虫物种之间既具有较高的保守同源性,同时也表现出一定的物种特异性.HDACs主要参与昆虫的胚胎发育、体节形成、寿命和神经行为等方面的调节.本文从HDACs蛋白的种类、系统发育、生理功能等方面展开,介绍了近年来国内外昆虫HDACs领域的最新研究进展,以期对研究昆虫表型可塑性调节机制以及探索新的害虫防治方法提供借鉴.     

A method for reducing error in estimating the effective accumulated temperature of the Helicoverpa armigera eclosion peak

为减小年际间气温变化对昆虫有效积温预测误差的影响,以新疆石河子垦区121团棉铃虫Helicoverpaarmigera(Hübner)羽化高峰期为例,利用single sine模型分别计算12年2种有效积温范围(10～30℃和10～35℃)的累计有效积温值,并获得其多年平均值,依此进行棉铃虫羽化高峰期预测;通过当年与12年(有效积温＞0日期至羽化高峰日期)平均气温之差,对预测误差进行校正.结果表明:当年平均气温与12年平均值差值越大,预测误差也越大;各代直线回归校正模型均达到显著水平(P＜0.05);2种有效积温范围下,校正后各代平均预测误差天数均有所减少,对越冬代误差校正效果最优,校正后各代历史符合率分别为83.33％、100％、100％和100％、100％、93.33％.该校正方法能够显著提高预测准确度,尤其适用于年际间棉铃虫发育期间平均气温变化较大的代别和地区,同时可为多种害虫预测误差校正提供了依据.