核仁和核仁蛋白

核仁是位于细胞核内的非膜结构。电子显微镜下的核仁从形态上可以分为三层结构包括纤维中心区(FC)、高密度纤维区(DFC)和颗粒区(GC)。核仁内的蛋白有核糖体蛋白和非核糖体蛋白两种。利用蛋白质组学方法已经鉴定了350多种核仁蛋白,其中包括80多种核糖体蛋白。核仁是核糖体合成的场所,核仁中的非核糖体蛋白对核糖体的生物合成起关键调控作用。核仁不仅是细胞内通讯和核糖体：RNA加工的中心,而且在细胞周期、细胞增殖和衰老中起重要调控作用;核仁也是tRNA、mRNA和其它类型小分子RNA加工的场所。因此核仁是一个多功能的细胞生命活动中心。     

八肋游仆虫酸性核糖体蛋白基因克隆与特征分析

原核和真核生物的核糖体大亚基上都存在着一类酸性核糖体蛋白,在大肠杆菌中,分别为L10和L7/L12蛋白,而在真核生物中是P0、P1和P2(简称P蛋白)。这些酸性核糖体蛋白共同组成五聚体复合物P0-(P1/P2)2,在大亚基上形成一个向外侧凸出的柄状结构(Ribosomalstalk)。酸性核糖体蛋白位于核糖体的活性部位,一方面     

循环包装回收技术在筛选肝癌细胞相关耐药基因中的应用

肝癌先天性多表达多药耐药基因,严重影响肝癌的化疗效果,筛选肝癌细胞中的耐药基因,研究其耐药机制有助于提高肝癌化疗效果,提高肝癌的治愈率。首先构建肝癌细胞逆转录病毒的cDNA文库,感染成纤维细胞,使得逆转录病毒基因整合进细胞,加药筛选,存活细胞中的基因再次包装成病毒,用于下一轮筛选。采用循环包装回收(Cyclical packaging rescue,CPR)技术进行肝癌细胞耐药基因的筛选即是通过病毒包装将基因从细胞中钓取出来,相比于常规筛选方法,仅通过一轮筛选可能会出现很多假阳性基因,采用CPR技术则是通过多轮筛选,很大程度减少了假阳性细胞的出现。通过该方法经过四轮筛选获得核糖体蛋白S11(RPS11)、核糖体蛋白L6(RPL6)、核糖体蛋白L11(RPL11)、核糖体蛋白L24(RPL24)等几种基因,经初步检测,增加了细胞的耐药性。     

核糖体失活蛋白的结构功能与分布

核糖体失活蛋白是一类在植物中较广泛存在的毒蛋白。植物核糖体失活蛋白具有RNAN-糖苷酶活力,可作用于核糖体RNA,使核糖体失去蛋白质合成的功能。根据一级结构,核糖体失活蛋白可分为两种类型。Ⅰ型核糖体失活蛋白由一条链组成,分子量在25—30 kDa之间。Ⅱ型核糖体失活蛋白由两条以二硫键相连的链(A、B链)组成,分子量在60 kDa左右。B链可以与细胞表面含半乳糖的受体结合,有助于A链进入细胞,作用于核糖体。目前至少已从9个科31种植物中分离纯化了Ⅰ型RIP。Ⅱ型RIP较少,仅在6科8种植物中发现。除了具有RNA N-糖苷酶活性,还发现一些核糖体失活蛋白可以切割超螺旋双链DNA,产生缺口环状和线状DNA。此外,一种Ⅰ型RIP,克木毒蛋白还具有超氧化物歧化酶活性。     

泛肽、核糖体蛋白及泛肽-核糖体蛋白S27a与肿瘤的关系

泛肽-核糖体蛋白S27a(Ubiquitin-ribosomal protein S27a,UBRS27a)是泛肽和核糖体蛋白的融合蛋白,N端为泛肽,C端由含C2-C2型锌指结构域的高度保守核糖体蛋白S27a构成。在真核细胞中表达时,被酶解成泛肽和核糖体蛋白。该多功能核糖体蛋白在各种活性增殖细胞和瘤组织中高度表达,在多种类型的肿瘤细胞中,该基因的过量表达是一个典型特征。本实验室对该蛋白在家蚕中的作了初步研究,也发现RPS27a在活性增殖细胞中表达量很高。大多数核糖体蛋白的功能还没有完全探明,它们不仅仅在组装成核糖体时起作用,往往还有核糖体外的功能。回顾了最近几年有关该融合蛋白以及与它相关的泛肽途径、核糖体蛋白与肿瘤之间的关系。通过对它们的研究,有可能预示肿瘤的发生和发展,并为肿瘤临床诊断提供依据,为恶性肿瘤的治疗提供靶点。     

天花粉蛋白引起敏感细胞膜上G蛋白激活的初步研究

天花粉蛋白(Trichosanthin,TCS)是一种单链核糖体失活蛋白,具引产、抗肿瘤、抗HIV等多种生物学功能。天花粉蛋白专一性杀伤敏感细胞的机制一直未被研究清楚。本文首次以生物分子相互作用分析(BIA)证明在天花粉蛋白敏感的细胞膜上存在着能与天花粉蛋白专一结合的组分。我们进一步利用[~(35)S]GTPγS结合实验发现天花粉蛋白能够激活敏感细胞膜上的G蛋白,而对不敏感细胞没有相应的G蛋白激活。这些结果表明了在敏感细胞膜上天花粉蛋白特异受体的存在。     

利用核糖体展示文库初步筛选与伤寒杆菌Ⅳ型纤毛结合的细胞受体

伤寒杆菌病原毒力岛上的Ⅳ型纤毛与伤寒杆菌的致病性密切相关,但对Ⅳ型纤毛在人巨噬细胞、树突状细胞上的受体及其序列或结合的关键部位还一无所知。本研究拟用核糖体展示库筛选伤寒杆菌结合的细胞受体。体外人工合成引物和含36个随机序列的寡核苷酸,通过两轮PCR构建随机DNA库,随后在体外进行偶联的转录和翻译,得到含随机12肽的核糖体库。利用含随机12肽的核糖体库与体外重组表达的Ⅳ型纤毛结构蛋白(PilS蛋白)进行了初步筛选,为筛选到与伤寒杆菌毒力岛上Ⅳ型纤毛结构蛋白结合的细胞受体奠定了基础。     

过表达EoRPL11下调HEK293T细胞中蛋白质的翻译活性(英文)

核糖体蛋白L11(RPL11)是真核生物核糖体的重要组成部分.RPL11参与核糖体的生物发生及其它的一些细胞调控过程.本研究在人细胞中研究了游仆虫RPL11(EoRPL11)的亚细胞定位及对蛋白质合成的调控功能.通过激光共聚焦显微镜观察发现,融合绿色荧光蛋白的EoRPL11分布于细胞核中,并集中于核仁上;将EoRPL11和海肾荧光素酶报告基因共转染HEK293T细胞后发现,细胞内海肾荧光素酶的酶活性明显下降,并呈现一种剂量依赖性关系;实时定量PCR分析则表明,海肾荧光素酶的mRNA水平并没有明显改变;同时,细胞的增殖也受到了一定的抑制.以上结果表明,EoRPL11是核蛋白,并且其过表达可能在翻译水平上抑制细胞内总蛋白质的合成.     

黄曲霉核糖体蛋白基因在不同生长时期的表达分析

核糖体是生物合成蛋白质的主要场所。核糖体蛋白是核糖体的重要组分之一。为了探究黄曲霉核糖体蛋白与其生长发育之间的关系,分别收集处于菌丝期、孢子期、菌核期的黄曲霉。在提取了总RNA和反转录获得了c DNA后,利用荧光定量RT-PCR对74个黄曲霉核糖体蛋白基因的表达量进行分析。结果表明,在所有被检测的核糖体蛋白基因中,没有一个基因的表达量在3个时期都是恒定的。与菌丝期相比,在孢子期,有54个核糖体蛋白基因的表达量发生上调,而表达量下调的基因只有2个;在菌核期,有57个基因的表达量上调,而有12个基因的表达量下调。GO功能分析表明,核糖体蛋白基因富集在结构分子活性,结合,细胞,大分子复合物,细胞器,细胞部分,细胞器部分,细胞过程,代谢过程。可见,核糖体蛋白与黄曲霉的生长发育存在紧密联系。     

核糖体灭活蛋白在植物中的作用

植物核糖体灭活蛋白 (ribosome -inactivatingproteins ,RIPs)能够破坏真核或原核细胞的核糖体大亚基RNA ,使核糖体失活而不能与蛋白质合成过程中的延伸因子相结合 ,从而导致蛋白质合成受到抑制。不同的核糖体对不同RIPs的敏感性不同 ,RIPs对自体或异体核糖体的作用也有很大区别。RIPs对病毒有很强的抑制作用 ,并且有些RIPs表现出对某些真菌和昆虫的抗性 ,因此认为核糖体灭活蛋白在植物的防御反应中扮演重要角色。另外 ,RIPs还可能参与了细胞代谢、细胞死亡等生理调控过程。     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Enterovirus 71 3C proteolytically processes the histone H3 N-terminal tail during infection

Highlights
1. The N-terminal tail of histone H3 is specifically cleaved during EV71 infection.
2. Viral protease 3C is identified as a protease responsible for proteolytically processing the N-terminal H3 tail.
3. Our finding reveals a new epigenetic regulatory mechanism for Enterovirus 71 in virus-host interactions.     

Detection of EBV and HHV6 in the Brain Tissue of Patients with Rasmussen’s Encephalitis

Rasmussen’s encephalitis (RE) is a rare pediatric neurological disorder, and the exact etiology is not clear. Viral infection may be involved in the pathogenesis of RE, but conflicting results have reported. In this study, we evaluated the expression of both Epstein-Barr virus (EBV) and human herpes virus (HHV) 6 antigens in brain sections from 30 patients with RE and 16 control individuals by immunohistochemistry. In the RE group, EBV and HHV6 antigens were detected in 56.7% (17/30) and 50% (15/30) of individuals, respectively. In contrast, no detectable EBV and HHV6 antigen expression was found in brain tissues of the control group. The co-expression of EBV and HHV6 was detected in 20.0% (6/30) of individuals. In particular, a 4-year-old boy had a typical clinical course, including a medical history of viral encephalitis, intractable epilepsy, and hemispheric atrophy. The co-expression of EBV and HHV6 was detected in neurons and astrocytes in the brain tissue, accompanied by a high frequency of CD8⁺ T cells. Our results suggest that EBV and HHV6 infection and the activation of CD8⁺ T cells are involved in the pathogenesis of RE.     

Perinatal Vertical Transmission of Chikungunya Virus in Ruili,a Town on the Border between China and Myanmar

正Dear Editor,Chikungunya virus (CHIKV), an arbovirus in the family of Togaviridae, genus Alphavirus, is transmitted by the A.aegyptii or A. albopictus mosquito, and causes disease in humans characterized by fever, rash, and arthralgia (Silva and Dermody 2017; Suhrbier 2019). It was first reported in 1953 in Tanzania, and caused only a few outbreaks and sporadic cases in Africa and Asia in last century. However, in the epidemic in 2004, CHIKV acquired mutations that conferred enhanced transmission by the A. albopictus mosquito(Schuffenecker et al. 2006). Since then, it has successively caused outbreaks in Africa, the Indian Ocean, South East Asia, the South America, and Europe (Zeller et al. 2016).     

Development of a Novel Reverse Transcription Loop-Mediated Isothermal Amplification Method for Rapid Detection of SARS-CoV-2

In conclusion, the novel visual RT-LAMP assay is a simple, rapid, and sensitive approach for detection of SARS-CoV-2, and it is ready for application in primary care and community hospitals or health care centers, and even patients' own houses in response to the current SARS-CoV-2 epidemic because the assay does not require sophisticated equipment and skilled personnel. Furthermore, it is also ready to be used in fields for screening samples from wild animals and environments to facilitate the identification of potential intermediate hosts that mediate the cross-species transmission of SARS-CoV-2 from bats to humans.