Galectin-7

Galectins are a family of animal lectins with an affinity for β-galactosides. They are differentially expressed by various tissues and appear to be functionally multivalent, exerting a wide range of biological activities both during development and in adult tissue. Galectin-7, a member of this family, contributes to different events associated with the differentiation and development of pluristratified epithelia. It is also associated with epithelial cell migration, which plays a crucial role in the re-epithelialization process of corneal or epidermal wounds. In addition, recent evidence indicates that galectin-7, designated as the product of the p53-induced gene 1 (PIG1), is a regulator of apoptosis through JNK activation and mitochondrial cytochrome c release. Defects in apoptosis constitute one of the major hallmarks of human cancers, and galectin-7 can act as either a positive or a negative regulatory factor in tumour development, depending on the histological type of the tumour. Received 30 October 2005; received after revision 15 November 2005; accepted 25 November 2005     

二氧化碳气体水合物生成特性的实验研究

在小型高压水合物反应装置上研究了二氧化碳水合物的生成特性.实验结果表明,静态系统下,二氧化碳气体在纯水体系中的生成速率非常缓慢,只在气-液界面处有一薄层浆状水合物生成.通过添加适当的表面活性剂可以有效改善气-水体系的传质阻力,增加气-水接触面,显著提高水合物的生成速率.     

标度

本书是剑桥大学出版社出版的《应用数学》丛书中的一本，详细论述了怎样建立和理解各种时问和空间尺度中物理问题的自相似解。     

Agonist-induced internalization and desensitization of the human nociceptin receptor expressed in CHO cells

In this study, we examined agonist-induced internalization, recycling and signalling (measure of cAMP levels) of the cloned human nociceptin receptor (hNOP) expressed in CHO-K1 cells. Internalization was proven by a receptor-binding assay on viable cells. The agonist nociceptin/orphanin FQ (NC) promoted rapid internalization of the hNOP receptor (approximately 78% of cell surface receptors were lost after 2 min exposure to 1 microM NC) in a clathrin- and ATP-dependent manner. Internalization was more rapid and marked in CHO-K1 cells than, as we previously reported, in SK-N-BE cells. This difference may be related to higher levels of beta-arrestin isoforms detected in CHO-K1 than in SK-N-BE cells. hNOP receptor internalization was partially reversible and recycling occurred in the presence of the agonist; receptor recycling was dependent on okadaic acid-sensitive phosphatases and was blocked by monensin. Confocal microscopy analysis confirmed the internalization and the recycling back to the plasma membrane of an epitope-tagged hNOP receptor expressed in CHO-K1 cells. These receptors underwent rapid desensitization upon agonist challenge: NC efficacy in inhibiting forskolin-stimulated cAMP production was significantly reduced 10 min after exposure and correlated with the rate of receptor internalization. Moreover, we observed that blockade of hNOP receptor recycling by monensin would cause a more prolonged and relevant desensitization of this receptor. Thus, the dynamic cycle between hNOP receptor activation, internalization and recycling determines the activity of this receptor on the cell surface.     

Phyllosilicates on Mars and implications for early martian climate

The recent identification of large deposits of sulphates by remote sensing and in situ observations has been considered evidence of the past presence of liquid water on Mars. Here we report the unambiguous detection of diverse phyllosilicates, a family of aqueous alteration products, on the basis of observations by the OMEGA imaging spectrometer on board the Mars Express spacecraft. These minerals are mainly associated with Noachian outcrops, which is consistent with an early active hydrological system, sustaining the long-term contact of igneous minerals with liquid water. We infer that the two main families of hydrated alteration products detected-phyllosilicates and sulphates--result from different formation processes. These occurred during two distinct climatic episodes: an early Noachian Mars, resulting in the formation of hydrated silicates, followed by a more acidic environment, in which sulphates formed.     

MATLAB入门：第二版适用于初高级用户

本书简明扼要地介绍了MATLAB7．0系统。主要内容包括MATLAB命令；MATLAB程序设计；图形、图表、图像模板；方程求解函数和丰富多彩的快捷界面。这些命令对低版本和高版本的MATLAB同样适用。数学计算与文本、图形相结合，形成新颖完整的交互式文件是MAT—LAB7．0的新特点。书中介绍的内容既兼顾了初学者，又顾及了熟悉MATLAB早期版本的用户。     

Casein kinase 1 gamma couples Wnt receptor activation to cytoplasmic signal transduction

Signalling by Wnt proteins (Wingless in Drosophila) has diverse roles during embryonic development and in adults, and is implicated in human diseases, including cancer. LDL-receptor-related proteins 5 and 6 (LRP5 and LRP6; Arrow in Drosophila) are key receptors required for transmission of Wnt/beta-catenin signalling in metazoa. Although the role of these receptors in Wnt signalling is well established, their coupling with the cytoplasmic signalling apparatus remains poorly defined. Using a protein modification screen for regulators of LRP6, we describe the identification of Xenopus Casein kinase 1 gamma (CK1gamma), a membrane-bound member of the CK1 family. Gain-of-function and loss-of-function experiments show that CK1gamma is both necessary and sufficient to transduce LRP6 signalling in vertebrates and Drosophila cells. In Xenopus embryos, CK1gamma is required during anterio-posterior patterning to promote posteriorizing Wnt/beta-catenin signalling. CK1gamma is associated with LRP6, which has multiple, modular CK1 phosphorylation sites. Wnt treatment induces the rapid CK1gamma-mediated phosphorylation of these sites within LRP6, which, in turn, promotes the recruitment of the scaffold protein Axin. Our results reveal an evolutionarily conserved mechanism that couples Wnt receptor activation to the cytoplasmic signal transduction apparatus.     

研究前沿:干细胞研究逐渐步入再生医学

再生医学作为相对较新的学科之所以被寄予厚望,在很大程度上是基于干细胞的研究进展。之所以说"新",举个例子,Regenerative Medicine创刊于2006年1月;而"很大程度"则是要强调再生医学的多学科性,比如它还需要生物工程技术。从某种程度上讲,"干细胞研究"和"再生医学"这两个词没有差别。上个月,威康信托和英国医学研究理事会宣布要在剑桥斥资1200万美元设立一个干细胞所,新的实验室计划占地约8000平方米,     

等离子体物理学与核聚变能

在过去的十余年里，随着石油价格的一路飚升，以及过渡使用化石燃料对环境造成的污染和破坏，人们越来越意识到，寻找干净、环保并且可以满足人类未来发展需求的替代能源已经刻不容缓。在世界范围内有越来越多的人已经明白这样一个现实：只有受控核聚变才能真正满足人类社会未来对能源和环境的需求。