人类溶酶体与溶酶体疾病

溶酶体是动物细胞的一种重要的细胞器,对体内多种生物大分子有消化作用,并参与细胞代谢、免疫以及激素分泌调节等活动。如果因某些原因溶酶体膜受损,溶酶体内的各种水解酶便会进入胞质并使细胞解体而产生矽肺、痛风等疾病。先天遗传因素造成的溶酶体功能缺陷会导致多种溶酶体贮积性疾病,这类疾病是新生儿出现的常见遗传病,对机体危害很大。溶酶体还与癌症、细胞老化及心脏、肝脏的某些疾病有密切关系。本文对近年来溶酶体及其相关疾病研究进展作一综述。     

溶酶体与细胞内吞作用

溶酶体是一种细胞器,最初由德杜弗(de Duve)等于1955年用分级分离技术从鼠肝细胞分离出来的。这是一种含有多种水解酶、对蛋白质、核酸和多糖等起溶解与消化作用的小体,故名为溶酶体。一、溶酶体的结构与发生溶酶体外面包有单层膜,形状和大小有一定的可变性,且与其消化活动的不同阶段有关。一般呈圆形小泡,直径约0.25～0.5     

真核细胞内蛋白质的降解途径

真核细胞内有数万种行使各种功能的蛋白质，在正常代谢条件下，蛋白质的合成和降解有精确的调节而处于动态平衡。内源性的蛋白质都有一定寿命，或长或短，最终命运是被降解。如果蛋白质的降解速率和位点出现异常，就会影响细胞的多种功能，如细胞分裂、信号传递等。目前发现真核细胞内有多条蛋白质降解途径，主要包括溶酶体途径、泛素一蛋白水解酶复合体通路、以及胱天蛋白酶(easpase)水解途径等。现简要介绍这几条途径。     

细胞的“净化系统”——溶酶体

本文介绍了溶酶体的结构和功能以及其参与的生物学过程。溶酶体是广泛分布于动物细胞中的一种囊状单层膜结构的细胞器,是细胞内的“消化车间”,能分解衰老、损伤的细胞器,吞噬并杀死入侵细胞的病毒或细菌,以维持细胞内部环境的稳定。在特殊情况下溶酶体可以将酶释放到细胞外进行胞外消化,多项研究证实人类的许多疾病发生可能与溶酶体有关。     

辨析“溶酶体”和“溶菌酶”

在高中生物学教学中,学生往往将溶酶体和溶菌酶混淆。实际上溶酶体是一种具有消化作用的细胞器,而溶菌酶是一种免疫活性物质。1认识溶酶体溶酶体是单层生物膜围成,内含60多种酸性水解酶类的囊泡状的一种异质性细胞器。1955年,科学家首次用电子显微镜看到了这种结构,并命名为"溶酶体",含义是溶解或消化小体。几乎所有的动物细胞中都存在溶酶体,例如巨噬细胞中含有数百个溶酶体。植物细胞内有与溶酶体功能类似的细胞器如圆球体、糊粉粒和中央液泡。但在细菌中没有发现溶酶体。根据其完成生理过程的不同阶段,可分为初级溶酶体、次级溶酶体和残余体[1]。     

说说溶酶体“那些事”

溶酶体是细胞中的"消化车间"。本文结合高考试题、细胞生物学知识和最新研究成果,综述溶酶体的发现、分布、结构、来源和在细胞生命活动中的重要作用。     

辨析内质网的结构和功能

细胞内膜系统是指在结构、功能乃至发生上相联系、由膜包被的细胞器或细胞结构,主要包括内质网、高尔基体、溶酶体、胞内体和分泌泡等。内质网的结构与功能在高中生物中多有应用：但许多同学对此并不是很了解,本文将对此进行总结和阐述,希望对大家的学校有所帮助。     

肿瘤发生过程中自噬与凋亡关系的研究

自噬是一种在进化上保守的真核细胞内的转运泡的运输机制,它可将细胞本身的亚细胞成分如蛋白、胞质或细胞器,通过溶酶体中的水解酶进行消化降解和循环。近期研究发现,自噬与凋亡相互作用可以从多种途径参与和调控肿瘤的发生及发展。本文对肿瘤发生过程中自噬与凋亡的关系作一综述。     

细胞自噬及相关试题分析

阐述细胞自噬的概念、方式和过程,及其与溶酶体的联系。简单比较了细胞自噬与异噬、细胞自噬与细胞凋亡和细胞坏死的区别,并结合相关试题进行分析说明。     

细胞自噬的作用机制及功能

细胞自噬是当今细胞生物学领域的热点问题之一,它是依赖溶酶体对胞质蛋白和细胞器进行降解的一种途径。近年来的研究表明,细胞自噬不仅仅是生物体在饥饿状态下获取能量的一种方式,而且与细胞内稳态的维持、个体发育、衰老,以及人类许多疾病的发生密切相关。     

What to Do About Zero Frequency Cells When Estimating Polychoric Correlations

Categorical structural equation modeling (SEM) methods that fit the model to estimated polychoric correlations have become popular in the social sciences. When population thresholds are high in absolute value, contingency tables in small samples are likely to contain zero frequency cells. Such cells make the estimation of the polychoric correlations more difficult. Some SEM programs use solutions such as adding .5 to the zero frequency cells. However, the adequacy of this solution has never been systematically explored in the literature. In this article, the frequency with which contingency tables with zero cells occur in small samples is explored. Second, it is explored whether or not adding .5 is in any way preferable to leaving the cell value as zero. Binary and 3-category data and a variety of threshold values and correlation values are considered. The findings suggest that the two methods of dealing with zero frequency cells have quite different properties. With binary data, the method of adding .5 is recommended, unless thresholds are opposite-signed and the underlying correlation is suspected to be large. No adjustment is recommended for greater numbers of categories.     

Roles of flotillins in tumors

The identification and use of molecular biomarkers have greatly improved the diagnosis and treatment of malignant tumors. However, a much deeper understanding of oncogenic proteins is needed for the benefit to cancer patients. The lipid raft marker proteins, flotillin-1 and flotillin-2, were first found in goldfish retinal ganglion cells during axon regeneration. They have since been found in a variety of cells, mainly on the inner surface of cell membranes, and not only act as a skeleton to provide a platform for protein–protein interactions, but also are involved in signal transduction, nerve regeneration, endocytosis, and lymphocyte activation. Previous studies have shown that flotillins are closely associated with tumor development, invasion, and metastasis. In this article, we review the functions of flotillins in relevant cell processes, their underlying mechanisms of action in a variety of tumors, and their potential applications to tumor molecular diagnosis and targeted therapy.     

A Talk on Language Characteristics of Advertising English

This article gives a lenthy and analytical account of the language characteristics of advertising English in terms of its semantic, syntactic and lexical features. As a variety of English, advertising English has gained more and more attention and been systematically studied.     

英语的中国本土化倾向研究

英语在世界范围内已经出现了诸多变体,但其在中国的变体最近20几年才逐步得到学术界认可。在目前阶段,学术界对于中国英语作为"英语本土化产物的语言变体"并未完全达成一致,实证研究尚未形成体系,但是中国英语所特有的表现力以及融入中国文化的英语表达方式必然会更加广泛地为人们所接受。     

巴斯德毕赤酵母表达系统研究进展

巴斯德毕赤酵母表达系统是应用较为成功的外源蛋白表达系统之一,它具有真核生物表达系统的特点,能够对目的蛋白进行类似高等真核生物的信号肽剪切、二硫键形成、糖基化等过程的翻译后蛋白加工,至今已有多种外源蛋白在该表达系统中成功表达.本文综述了毕赤酵母表达系统的一些特点和优势、毕赤酵母表达载体组成和外源蛋白在毕赤酵母中表达的过程.     

新型组合结构节点研究进展

随着组合结构在工程中的应用越来越普遍,组合结构梁柱节点的设计与研究成了研究工作的重点内容之一.目前,已有多种组合节点被应用于实际结构中,取得了较好的效果.试对RCS组合节点、端板螺栓连接节点、CSRC组合节点的特点和研究中存在的问题进行了分析.     

Prospects for the Development of Private Higher Education in Poland

The development of private (non-state) higher education institutions in Poland has been a phenomenon of increasing importance since 1990. It is a paradox of their existence, particularly in small towns with no previous tradition of higher education, that they have been more successful than the state higher education institutions in educating young people of working-class and peasant background, even though they charge tuition fees. In many ways, the private higher education institutions are more responsive to the demands of an economy in transition than are the state institutions, and they tend to operate more efficiently. Also, they have been rapid to adopt the "Mode 2" variety of knowledge generation. The creation of private higher education institutions has been a stimulus to regional development in Poland.     

回环的构建及现代运用特征

作为汉语中一种古老的、具有独特魅力的修辞方式，回环在现代语言交际中仍被广泛使用，并且呈现出范围更广、用法更活、更注重语义内涵等多种特点。其中，加大信息负载量是当今回环运用内容上最突出的特征，在齐整中追求变化是其形式上最显著的特色。     

在专业课程框架下培养高职生的关键能力研究——基于国际商务专业的统计分析

关键能力是个人职业生涯中除岗位专业能力之外的基本能力,它适用于各种职业,适应岗位的不断变换,是伴随其终生的可持续发展能力。具备关键能力成为众多企业对人才的迫切需求,因此,高职院校越来越重视对学生关键能力的培养。调研显示,国际商务专业在专业课程中的外语学习、信息处理以及与人交流能力培养等方面效果都较好,教学方法多样有效,而解决问题、与人合作能力则需要进行更多的探索。     

Hypermedia in education

Conclusion Hypermedia programs come in a wide variety of forms for virtually all of the Apple computers being used in schools. Never before has such powerful computing been so easy and accessible. With existing programs being constantly improved and upgraded and new programs appearing on the market more and more frequently, it might not be long before the term“hyper-student” takes on a new and more positive meaning.