Psb30 contributes to structurally stabilise the Photosystem II complex in the thermophilic cyanobacterium Thermosynechococcus elongatus

A deletion mutant that lacks the Psb30 protein, one of the small subunits of Photosystem II, was constructed in a Thermosynechococcus elongatus strain in which the D1 protein is expressed from the psbA₃ gene (WT*). The ΔPsb30 mutant appears more susceptible to photodamage, has a cytochrome b₅₅₉ that is converted into the low potential form, and probably also lacks the PsbY subunit. In the presence of an inhibitor of protein synthesis, the ?Psb30 lost more rapidly the water oxidation function than the WT* under the high light conditions. These results suggest that Psb30 contributes to structurally and functionally stabilise the Photosystem II complex in preventing the conversion of cytochrome b₅₅₉ into the low potential form. Structural reasons for such effects are discussed.     

滋补肾阴方与温补肾阳方对卵巢切除所致骨质疏松大鼠治疗作用的对比研究

目的　对比观察滋补肾阴方与温补肾阳方对卵巢切除所致骨质疏松大鼠的治疗作用 ,以探讨它们之间的疗效是否存在差异。方法　将雌性Wistar大鼠 4 9只随机分为正常对照组、假手术组、卵巢切除组、滋阴组 (灌服生药含量为 1 0 5g ml的滋补肾阴方 ,按每 10 0g体重 0 7ml剂量 )、补阳组 (灌服生药含量为 0 78g ml的温补肾阳方 ,按每 10 0g体重 0 7ml剂量 )。于造模 3个月后开始给药 ,1次 日 ,连续 6d ,休息一天后 ,再连续灌服 6d。给药 2个月后 ,将大鼠处死 ,取胫骨行不脱钙骨切片 ,甲苯胺蓝染色 ,对其进行骨组织形态计量。结果　切除卵巢 5个月后 ,大鼠胫骨TBV %显著降低 ,TRS %以及TFS %、AFS %、MAR、BFR、OSW和mAR皆显著增高 ,给大鼠灌服滋阴补肾方和温补肾阳方 2个月后 ,均能使上述指标发生逆转 ,但程度有所不同 ,温补肾阳方的效果要明显优于滋补肾阴方。结论　滋补肾阴方与温补肾阳方对卵巢切除所致的骨质疏松均有明显的治疗作用 ,但温补肾阳方的疗效要优于滋阴补肾方。     

A divergent synthesis of [1-14C]-mono-E isomers of fatty acids

A convenient synthesis of [1-14C]-mono-trans fatty acid using olefin inversion as a key-step is described. This methodology allows for a facile synthesis of [1-14C]-labelled mono-trans analogues of oleic, linoleic and linolenic acids. As an example, only eleven steps were necessary to obtain the [1-14C]-mono-E isomers of linolenic acid from its commercial all-Z form. In the first step, Barton's decarboxylation procedure yielded a bromo intermediate. Epoxidation of this compound resulted in the formation of three monoepoxides, which could be separated by HPLC. After identification by 1H NMR and MS, the pure monoepoxides were then subjected to inversion consisting of a stereospecific deoxygenation followed by a beta-elimination step. Finally, the labelling was introduced by substitution of the bromine by a [14C]-cyano group followed by hydrolysis.     

Electrotonic and action potentials in the Venus flytrap

The electrical phenomena and morphing structures in the Venus flytrap have attracted researchers since the nineteenth century. We have observed that mechanical stimulation of trigger hairs on the lobes of the Venus flytrap induces electrotonic potentials in the lower leaf. Electrostimulation of electrical circuits in the Venus flytrap can induce electrotonic potentials propagating along the upper and lower leaves. The instantaneous increase or decrease in voltage of stimulating potential generates a nonlinear electrical response in plant tissues. Any electrostimulation that is not instantaneous, such as sinusoidal or triangular functions, results in linear responses in the form of small electrotonic potentials. The amplitude and sign of electrotonic potentials depend on the polarity and the amplitude of the applied voltage. Electrical stimulation of the lower leaf induces electrical signals, which resemble action potentials, in the trap between the lobes and the midrib. The trap closes if the stimulating voltage is above the threshold level of 4.4 V. Electrical responses in the Venus flytrap were analyzed and reproduced in the discrete electrical circuit. The information gained from this study can be used to elucidate the coupling of intracellular and intercellular communications in the form of electrical signals within plants.     

基于传统生态智慧的江南水网空间韧性机制及实践启示

传统江南水网空间是一种典型的社会—生态系统,人文社会系统和自然生态系统之间的良性互动对于其韧性构建有着重要的积极作用。基于柯林斯等人提出的压力—冲击动态（PPD）模型,以平江府为典型代表,研究传统江南水网空间如何通过生态系统服务的桥梁搭建水网物质空间与人类社区发展之间的联系,从而厘清社会—生态系统在此过程中如何培育、优化和提升江南水网空间韧性。在此基础上,创新性地从生态系统服务供需关系的角度提出社会—生态韧性构建的生态智慧,并倡导以恢复力、适应力与变革力韧性机制培育为导向的、江南地区构建现代社区实践的若干启示,旨在引导江南水网空间实现具有韧性的社会—生态系统转型发展。     

脑部磁刺激场的理论模型

作为脑部磁刺激研究的一项基础工作,建立了刺激磁场中的球形头模型、对方形线圈在其内产生的时变磁场和感应电场进行了理论研究.导出(?).(?).(?)的解析表达式,分析了场的特性和刺激强度的分布规律.为进一步探索时变磁场对人脑的最佳刺激方式和作用机理提供了初步的理论基础.     

鳙团移核鱼的形态性状与个体生长

本文报道了鳙国移核鱼的形态性状及其个体生长等特性,为研究核质关系和细胞质遗传提供了一些有价值的结果．鳙团移核鱼的形态性状有些与供核体鳙鱼相似,有的与受核体团头纺相似,还有的出现中间型性状。二龄移核鱼的生长都明显比团头纺快,但都慢于鳙鱼．     

Liposome-mediated labeling of adrenocorticotropin fragments parallels their biological activity

To test our hypothesis that specific interactions of ACTH peptides with model lipid membranes reflect the biological importance of similar interactions on target cells, we investigated the liposome-mediated labeling of ACTH fragments with the extremely hydrophobic photolabel, 3-trifluoromethyl-3-(m-[125I]iodophenyl)diazirine. Correlations were found between the labeling rates and the agonistic and antagonistic potencies of the peptides for in vitro steroidogenesis and inhibition of a synaptosomal protein kinase. A model for the cross-reactivity between ACTH and opioid peptides is discussed.