甲醛诱导Tau蛋白形成“孔道样”聚集结构

尽管Lin等(University of California, Santa Barbara)就蛋白构象病中细胞死亡的机制提出了“非特异性淀粉样离子通道”(aspecific amyloid ion channels)学说,但到目前为止,尚未发现神经Tau蛋白能形成“孔道样”聚集结构,也未寻找到可以导致蛋白质形成“孔道样”聚集结构的诱导剂．依据本实验室提出的“散发性老年痴呆发生发展中的内源性甲醛慢性损伤”假说,采用一定浓度的甲醛与Tau蛋白进行温育,观察到甲醛可以明显诱导Tau蛋白分子聚集并形成淀粉样沉积物,同时也观察到了Tau蛋白“孔道样”聚集结构．上述结果为探索甲醛诱导Tau蛋白错误折叠形成的产物导致细胞代谢障碍和死亡的机制提供了新的研究思路．     

甲醛导致细胞周期异常的浓度选择性

一定浓度的甲醛可以引起蛋白质的异常修饰、功能丧失、细胞死亡。虽然甲醛的细胞毒性已见报道,但甲醛影响神经细胞周期及其分子机制等尚不明确．本文采用不同浓度甲醛与神经母细胞瘤细胞系SH-SY5Y共孵育,观察到甲醛对细胞周期的影响取决于甲醛的浓度．当甲醛浓度([FA])≤0.1 mmol/L(细胞培养48 h),细胞周期与对照相比,无显著性差异．当甲醛浓度增加(0.1 mmol/L <[FA]≤0.2 mmol/L),S期和G2/M期细胞比例显著增加;当[FA] = 0.3 mmol/L时,细胞增殖被显著抑制,大量细胞滞留在S期(46.28%),G2/M期细胞仅占16.05%．将细胞同步到G2/M期,用0.1～0.3 mmol/L甲醛孵育,尽管G2/M期细胞都有一定程度的减少,但S期细胞显著增加;将细胞同步化到S期,与0.1 mmol/L甲醛孵育,则G2/M期细胞有一定程度的减少;与0.3 mmol/L甲醛孵育,表现为G2/M细胞显著减少,S期细胞极度增加．在相同条件下,Sprague-Dawley (SD)大鼠原代皮层神经元,也表现出G2/M期细胞比例随甲醛浓度升高而降低,S期细胞比例随之增加的现象．当0.1 mmol/L≤[FA]≤0.2 mmol/L时,细胞出现明显的早期或晚期凋亡;当[FA]≥0.3 mmol/L时,DNA损伤明显,细胞出现凋亡和部分坏死．以上结果提示,低浓度甲醛(0.1 mmol/L≤[FA]≤0.2 mmol/L)主要通过引起DNA超甲基化而抑制S期DNA的合成,高浓度甲醛([FA]≥0.3 mmol/L)则造成DNA的损伤,从而影响细胞周期的进程．     

内源性甲醛与心血管疾病

内源性甲醛是甲胺由氨基脲敏感性胺氧化酶催化而生成,广泛存在于动物体内多种组织细胞。已经证实,内源性甲醛参与了神经变性病、免疫性疾病以及肿瘤等疾病的发病过程。脂肪细胞、血管内皮细胞和平滑肌细胞富含甲醛生成酶氨基脲敏感性胺氧化酶(semicarbazide-sensitive a-mine oxidase,SSAO)。甲醛具有细胞毒性,易损伤血管内皮并介导多种致病因素诱导的血管损伤过程,在动脉粥样硬化和糖尿病及其并发症的发病中都具有重要作用。     

活性氧参与一氧化氮诱导的神经细胞凋亡

采用激光共聚焦成像技术，用氧化还原敏感的特异性荧光探针(DCFH-DA和DHR123)直接研究了一氧化氮供体S-亚硝基-N-乙酰基青霉胺(SNAP)诱导未成熟大鼠小脑颗粒神经元凋亡过程中的细胞胞浆、线粒体中活性氧水平的变化，发现神经细胞经0.5 mmol/L SNAP处理1 h后，细胞胞浆及线粒体中活性氧水平大大增加.一氧化氮清除剂血红蛋白能够有效抑制细胞胞浆、线粒体中活性氧的产生，防止细胞凋亡.外源性谷胱甘肽对细胞也具有良好的保护作用，而当细胞中谷胱甘肽的合成被抑制后，一氧化氮的神经毒性大大增强.实验结果表明一氧化氮通过促进神经细胞产生内源性活性氧而启动细胞凋亡程序，而谷胱甘肽可能是重要的防止一氧化氮引发神经损伤的内源性抗氧化剂.     

甲醛对DNA损伤的彗星实验研究

甲醛是一种遗传毒性物质。国内外学者的大量研究证实,甲醛可以引起DNA-DNA、DNA-蛋白质分子交联,但对于甲醛是否能够引起DNA分子的断裂,学界却存在分歧。本实验以颊黏膜细胞作为实验材料,通过彗星实验对甲醛的遗传毒性——尤其是DNA分子断裂作用进行了系统的研究。结果显示甲醛在较低浓度(5μmol／L,7,5μmol／L,10μmol／L)时具有断裂作用,在较高浓度(15μmol／L,30μmol／L,50μmol／L)时则具有交联作用。根据本实验的结果,本文还首次论证了甲醛断裂作用的断裂峰值(7．5μmol／L)。     

Paraoxonase-1介导硫化氢的抗甲醛神经毒性作用

我们以往的研究工作证实了硫化氢(hydrogen sulfide,H2S)对甲醛神经毒性和氧化应激具有拮抗作用.Paraoxonase-1(PON-1)是机体重要的内源性抗氧化剂.本研究的目的是探讨PON-1是否可介导H2S的抗甲醛神经毒性作用.采用甲醛损伤PC12细胞为甲醛神经毒性的细胞模型.硫氢化钠(NaHS,一种H2S的供体)不仅可以上调PC12细胞PON-1的活力,还可恢复甲醛对PC12细胞PON-1表达与活力的抑制作用.2-hydroxyquinoline(2-HQ)是一种选择性PON-1抑制剂,它可显著降低H2S对甲醛细胞毒性、凋亡和活性氧(reactive oxygen species,ROS)累积的抑制作用.而且,2-HQ可阻止H2S逆转甲醛激活PC12细胞caspase-3和下调PC12细胞bcl-2表达.结果提示H2S依赖PON-1去保护PC12细胞对抗甲醛的神经毒性.我们的这一发现表明PON-1有希望成为防治甲醛神经损伤的新靶点.     

甲醛对DNA损伤的彗星实验研究

甲醛是一种遗传毒性物质。国内外学者的大量研究证实,甲醛可以引起DNA-DNA、DNA-蛋白质分子交联,但对于甲醛是否能够引起DNA 分子的断裂,学界却存在分歧。本实验以颊黏膜细胞作为实验材料,通过彗星实验对甲醛的遗传毒性——尤其是DNA 分子断裂作用进行了系统的研究。结果显示甲醛在较低浓度(5μmol/L,7.5μmol/L,10μmol/L)时具有断裂作用,在较高浓度(15μmol/L,30μmol/L,50μmol/L)时则具有交联作用。根据本实验的结果,本文还首次论证了甲醛断裂作用的断裂峰值(7.5μmol/L)。     

内源性甲醛异常蓄积与记忆衰退

近期,本实验室报道了内源性甲醛浓度与认知功能损伤程度之间的关系(Neurobiol Aging,2011,32(1):31-41).观察到转基因痴呆小鼠(APP、APP/PS1)及衰老加速型(SAMP8)小鼠脑内甲醛浓度较对照组显著升高.参照痴呆鼠脑内甲醛浓度,实验人员对正常成年小鼠进行注射,导致其视觉空间记忆能力减退.注射甲醛消除剂可以降低老龄大鼠体内甲醛浓度、减少APP痴呆模型小鼠脑内的老年斑,且能观察到记忆功能的改善.临床观察显示,老年痴呆患者尿甲醛浓度与认知功能损伤程度之间呈正相关.甲醛的过量蓄积造成脑慢性损伤,可能是散发性老年记忆衰退的机制之一.     

活性氧参与-氧化氮诱导的神经细胞凋亡

采用激光共聚焦成像技术,用氧化还原敏感的特异性荧光探针(DCFH-DA和DHR123)直接研究了一氧 化氮供体S-亚硝基-N-乙酰基青霉胺(SNAP)诱导未成熟大鼠小脑颗粒神经元凋亡过程中的细胞胞浆、线粒体 中活性氧水平的变化,发现神经细胞经0.5mmol/LSNAP处理1h后,细胞胞浆及线粒体中活性氧水平大大增 加.一氧化氮清除剂血红蛋白能够有效抑制细胞胞浆、线粒体中活性氧的产生,防止细胞凋亡.外源性谷胱甘 肽对细胞也具有良好的保护作用,而当细胞中谷胱甘肽的合成被抑制后,一氧化氮的神经毒性大大增强.实验 结果表明一氧化氮通过促进神经细胞产生内源性活性氧而启动细胞凋亡程序,而谷胱甘肽可能是重要的防止一 氧化氮引发神经损伤的内源性抗氧化剂     

病理浓度甲醛的累积导致小鼠神经母瘤细胞活力及黏附能力下降（英文）

衰老相关的认知损伤,如阿尔茨海默病(AD),是一种缓慢、渐进、不可逆的神经退行性疾病.内源(尿)甲醛浓度与AD病人的认知损害程度呈正相关.但是,在以前研究中所采用的甲醛浓度,通常高于AD患者和老年人的病理和生理浓度.因此,研究长时程低浓度(病理浓度)甲醛对神经类细胞的影响,对于揭示甲醛在AD发生发展过程的作用是非常必要的.本文参照AD患者尿甲醛浓度,采用每隔24 h连续传代接种加甲醛(10μmol/L)的方式,模拟AD病人尿甲醛浓度,观察长时程甲醛的累积对小鼠神经母瘤细胞(N2a)和原代海马神经元的影响.通过高效液相色谱、细胞活力和乳酸脱氢酶释放检测显示,随着孵育时间的延长,培养基内甲醛浓度积累升高,N2a细胞生长受到抑制,在甲醛孵育的后期,细胞死亡显著增加.全息成像显示,长时程病理浓度甲醛的积累,使细胞厚度增加、面积减小、神经突受损、显著削弱细胞的黏附能力.同样条件下,小鼠原代海马神经元的一级神经突的数目显著降低,表明病理浓度甲醛的积累能够削弱神经元之间的连接.免疫印迹和免疫荧光染色显示,甲醛的累积可以使N2a细胞内Tau蛋白的181位苏氨酸(T181)和396位丝氨酸(S396)磷酸化水平显著上升,可能是甲醛累积导致的神经突减少和形态改变的因素之一.以上结果证明,病理浓度甲醛在细胞生存环境中的累积,可以导致神经细胞损伤,尤其是神经突的异常改变.本文为探索甲醛代谢失调与老年认知损害之间关系和机制提供了新的启示.     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.