Synergistic response to oncogenic mutations defines gene class critical to cancer phenotype

Understanding the molecular underpinnings of cancer is of critical importance to the development of targeted intervention strategies. Identification of such targets, however, is notoriously difficult and unpredictable. Malignant cell transformation requires the cooperation of a few oncogenic mutations that cause substantial reorganization of many cell features and induce complex changes in gene expression patterns. Genes critical to this multifaceted cellular phenotype have therefore only been identified after signalling pathway analysis or on an ad hoc basis. Our observations that cell transformation by cooperating oncogenic lesions depends on synergistic modulation of downstream signalling circuitry suggest that malignant transformation is a highly cooperative process, involving synergy at multiple levels of regulation, including gene expression. Here we show that a large proportion of genes controlled synergistically by loss-of-function p53 and Ras activation are critical to the malignant state of murine and human colon cells. Notably, 14 out of 24 'cooperation response genes' were found to contribute to tumour formation in gene perturbation experiments. In contrast, only 1 in 14 perturbations of the genes responding in a non-synergistic manner had a similar effect. Synergistic control of gene expression by oncogenic mutations thus emerges as an underlying key to malignancy, and provides an attractive rationale for identifying intervention targets in gene networks downstream of oncogenic gain- and loss-of-function mutations.     

基于GIS的重庆市洪灾综合风险评估研究

洪涝灾害作为自然灾害的重要险种之一,严重影响了人类的生产生活.根据自然灾害风险评估理论,以重庆市为研究对象,从洪灾危险性、敏感性和易损性3个角度出发,选取降水、地形、植被指数、单位面积GDP等8个评价要素指标,以县级行政区划作为评估单元,利用GIS空间分析功能对重庆洪灾进行综合风险评估,结果表明,洪灾危险性、敏感性和易损性均表现出较为明显的空间地域特征,危险性呈由西向东逐级递增的特点,峰值集中在渝东南和渝东北的两翼地区;受地形、河网密度和植被指数综合影响,洪灾敏感性指标分布与长江干流流向体现出了高度的空间相关性,峰值集中在长江干流沿岸的永川、江津、江北、涪陵、垫江等区县;而易损性指标则基本上与重庆市社会经济发展空间分布相吻合.综合来看,研究区洪灾风险等级整体呈现出由西向东减小的趋势,经济较发达的主城、渝西地区风险等级较高,经济欠发达的渝东南、渝东北地区风险等级较小.     

Realization of the Cirac-Zoller controlled-NOT quantum gate

Quantum computers have the potential to perform certain computational tasks more efficiently than their classical counterparts. The Cirac-Zoller proposal for a scalable quantum computer is based on a string of trapped ions whose electronic states represent the quantum bits of information (or qubits). In this scheme, quantum logical gates involving any subset of ions are realized by coupling the ions through their collective quantized motion. The main experimental step towards realizing the scheme is to implement the controlled-NOT (CNOT) gate operation between two individual ions. The CNOT quantum logical gate corresponds to the XOR gate operation of classical logic that flips the state of a target bit conditioned on the state of a control bit. Here we implement a CNOT quantum gate according to the Cirac-Zoller proposal. In our experiment, two 40Ca+ ions are held in a linear Paul trap and are individually addressed using focused laser beams; the qubits are represented by superpositions of two long-lived electronic states. Our work relies on recently developed precise control of atomic phases and the application of composite pulse sequences adapted from nuclear magnetic resonance techniques.     

The genome of a motile marine Synechococcus

Marine unicellular cyanobacteria are responsible for an estimated 20-40% of chlorophyll biomass and carbon fixation in the oceans. Here we have sequenced and analysed the 2.4-megabase genome of Synechococcus sp. strain WH8102, revealing some of the ways that these organisms have adapted to their largely oligotrophic environment. WH8102 uses organic nitrogen and phosphorus sources and more sodium-dependent transporters than a model freshwater cyanobacterium. Furthermore, it seems to have adopted strategies for conserving limited iron stores by using nickel and cobalt in some enzymes, has reduced its regulatory machinery (consistent with the fact that the open ocean constitutes a far more constant and buffered environment than fresh water), and has evolved a unique type of swimming motility. The genome of WH8102 seems to have been greatly influenced by horizontal gene transfer, partially through phages. The genetic material contributed by horizontal gene transfer includes genes involved in the modification of the cell surface and in swimming motility. On the basis of its genome, WH8102 is more of a generalist than two related marine cyanobacteria.     

重庆市土地利用结构与产业结构耦合协调发展评价

基于耦合协调发展度和相对发展度模型,以重庆市为研究对象,运用变异系数法对重庆市1997-2012年土地利用结构与产业结构的耦合协调发展进行了测算分析.研究结果表明:1重庆市土地利用结构综合指数和产业结构综合指数呈现波动上升趋势;2重庆市土地利用结构与产业结构的耦合协调发展度在不断上升,处于一般协调耦合阶段.表明土地利用结构与产业结构相互促进、配合得当,整体协调向前发展;3土地利用结构与产业结构的相对发展度变化较小,表明土地利用结构与产业结构在对应时期的发展速度和方向日趋一致.     

西南山区生态敏感区生态服务价值对土地利用变化的响应——以重庆市万州区为例

生态系统服务价值评估是当前土地科学研究的热点问题之一.本文以重庆市万州区为研究区,依据2000—2008年土地变更调查资料,采用Costanza生态系统服务价值计算公式,运用生态经济学方法,分析了研究区生态系统服务功能对土地利用变化的响应.研究结果表明:研究区在2000—2008年间,农田、园地、湿地、未利用地均减少,林地、草地、水域、城镇用地、道路用地均增加.研究期内生态系统服务价值总体有所上升,从355.19×107元上升到418.2×107元,增加了63.01×107元.农田、林地、水域是生态系统服务价值构成中贡献最大的土地利用类型,占到生态系统服务价值的95%以上,对整个区域生态服务价值的变化起着决定作用.研究区生态建设与经济发展已处于低度协调的边缘,区域未来的发展必须重视对生态环境的治理和保护.     

新型农村社区农户生态满意度影响因素分析——以整村推进示范区“大柱新村”为例

基于结构方程模型构建农户生态满意度模型,定量分析各变量对农户生态满意度的影响程度.结果表明:各外生潜变量对农户生态满意度的影响差异明显,其中农户对住宅特性的认知影响最大,农户自身特性及农户对公共空间特性、社区周边环境特性、政府行为的认知影响次之;农户自身特性对其余4个外生潜变量影响显著;外生观测变量中行道树功能、清洁能源使用情况、住宅内部空间布局对农户生态满意度的影响非常明显.农户生态满意度模型对于测度农户主观感知具有较强的适用性,其结果既诠释了农户"自下而上"需求,也为政府及规划者突显农户主体地位的"自上而下"规划提供了理论指导.     

Monoamine oxidases in development

Monoamine oxidases (MAOs) are flavoproteins of the outer mitochondrial membrane that catalyze the oxidative deamination of biogenic and xenobiotic amines. In mammals there are two isoforms (MAO-A and MAO-B) that can be distinguished on the basis of their substrate specificity and their sensitivity towards specific inhibitors. Both isoforms are expressed in most tissues, but their expression in the central nervous system and their ability to metabolize monoaminergic neurotransmitters have focused MAO research on the functionality of the mature brain. MAO activities have been related to neurodegenerative diseases as well as to neurological and psychiatric disorders. More recently evidence has been accumulating indicating that MAO isoforms are expressed not only in adult mammals, but also before birth, and that defective MAO expression induces developmental abnormalities in particular of the brain. This review is aimed at summarizing and critically evaluating the new findings on the developmental functions of MAO isoforms during embryogenesis.