筛选冠突伪尾柱虫有小核细胞系和无小核细胞系饥饿期差异表达的ESTs

利用显微切割的方法建立大型腹毛目纤毛虫---冠突伪尾柱虫(Pseudourostyla cristata)的无小核细胞系,分别提取有小核和无小核细胞系的总RNA,用SMART-PCR方法直接合成dscDNA,进而运用抑制性消减杂交技术(Sup-pression subtractive hybridization,SSH)对冠突伪尾柱虫去小核前后的差异表达基因进行研究,构建了有与无小核细胞系在饥饿期差异表达基因的消减文库,随机挑取了284个克隆,应用cDNA阵列技术鉴定阳性克隆。将鉴定出的17个阳性克隆进行Blastx分析,结果表明17个EST(Expressed sequence tag)均可能与小核体功能密切相关,此为进一步阐明小核的遗传机理奠定了基础。       

冠突伪尾柱虫小核对胞口结构稳定性的影响

在通过显微手术所建立的冠突伪尾柱虫（Pseudourostyla cristata)无小核系中,部分细胞因口围带翻领部小膜出现不同程度的缺损而导致畸形;在细胞生长静止期的群体中,口围带畸形率高达50％以上;对无小核系600多个刚完成二分裂的前,后仔虫及1000多个生理改组末期的虫体进行蛋白银染色观察,除发现4个二分裂仔虫和3个生理改组后虫体的口围带异常外,绝大多数经过形态发生后的细胞都具有正常的胞口结构。另一方面,选择性培养实验进一步证明,口围带畸形产生于非形态发生期。由此可见,失去小核的细胞,同时也失去了胞口结构的稳定性。     

冠突伪尾柱虫接合过程中小核的形态发生作用

为查明有性生殖期间小核对形态发生的影响程度和范围 ,我们利用蛋白银染色对冠突伪尾柱虫不同交配型无小核体之间的接合过程进行了跟踪观察。结果表明 :无小核细胞的交配反应能力明显下降 ;接合双方第一次皮膜形态发生如常进行 ,但纤毛器原基分化往往出现异常 ;接合后体照常进入拟包囊阶段 ,但原有纤毛器多不从皮膜上消失 ;由于没有新核器形成 ,均不能启动第二次形态发生并于拟包囊早期解体死亡。因此 ,小核对于维持接合早期及第一次皮膜改组的正常进行具有某些明显作用 ,其衍生的大核原基对于启动后续的发育则是绝对必要的     

冠突伪尾柱虫有性生殖期间皮膜发育的核控制

通过显微手术去小核建立多个冠突伪尾柱虫（Pseudourostyla cristata)无小细胞系,并诱导它们与有小核细胞进行接合生殖,以评估小核及其衍生的大核原基在有性生殖期间对皮膜形态发生的影响,当无小核接合体从有小核配偶获得1枚配子核后,接合双方不仅能平行地继续核器演化,而且使第1次皮膜改组能够同步进行和正常发育,说明小核在有性周期中除了生殖功能外仍保留着某些控制皮膜发育的体功能,虽然大部分接合后体的大核原基在DNA贫乏期停止发育,但少数接合后体能够超越这一时期,并启动第2次皮膜改组和顺利完成其后续的有性发育全程,表明指令发动第2次皮膜发育的信号来自DNA贫乏期后以排出一核物质团块为标志的大核原基。     

长江口地区五种腹毛类纤毛虫的形态学研究

利用活体观察和蛋白银染色技术, 对采自长江口泥滩潮间带及河道的五种腹毛类纤毛虫进行了形态学研究。包括对两个国内新记录种仁川巴库虫Bakuella (Bakuella) incheonensis和希斯多利织毛虫Histriculus histrio提供了详细的活体特征和纤毛图式信息, 对红色伪角毛虫Pseudokeronopsis rubra、黄色伪角毛虫Pseudokeronopsis flava和冠突伪尾柱虫Pseudourostyla cristata进行了形态学重描述。五种腹毛类纤毛虫的长江口种群与国内外种群均存在不同程度的形态学差异: 仁川巴库虫较韩国原始种群体型大, 口围带小膜和额前棘毛数较多; 希斯多利织毛虫与部分国外种群存在体长差异; 红色伪角毛虫与青岛种群相比形态特征基本吻合但个体大小的波动范围较大; 黄色伪角毛虫与湛江种群相比额棘毛数目较多; 冠突伪尾柱虫较奥地利种群体型较小, 与日本种群相比大核较多。该工作丰富了中国腹毛类纤毛虫多样性的认识。     

冠窦伪尾柱虫接合过程中小核的形态发生作用

为查明有性生殖期间小核对形态发生的影响程度和范围,我们利用蛋白银染色对冠突伪尾柱虫不同交配型无小核体之间 的接合过程进行了跟踪观察。结果表明：无小核细胞的交配反应能力明显下降;接合双方第一次皮膜形态发生如常进行,但纤毛器原基分化往往出现异常;接合后体照常进入拟包囊阶段,但原有纤毛器多不从皮膜上消失。由于没有新核器形成,均不能启动第二次形态发生并于拟包囊早期解体死亡。因此,小核对于纤维接合早期及第一次皮膜改组的正常进行具有某些明显作用,其衍生的大核原基对于启动后续的发育则是绝对必要的。     

冠突伪尾柱虫营养期和形成包囊期间细胞的超微结构

冠突伪尾柱虫营养细胞中含有轴杆样结构。细胞形成包囊期间,胞质内发生自噬作用,并产生由这聚集在一起组成的高尔基体,在高尔基体内其分泌物质聚集成高电子密度的嗜锇晶体。细胞分化的结果形成含膜粒层,内层壁和外层壁的“尾柱虫类包囊”。     

三种纤毛虫细胞内酸性磷酸酶的定位观察

利用电镜酶细胞化学方法,对大尾柱虫(Urostylagrandis)、冠突伪尾柱虫(Pseudourostylacristata)、魏氏拟尾柱虫(Paraurostylaweissei)三种纤毛虫细胞内的酸性磷酸酶(ACPase)进行了定位观察。发现在它们体内ACPase的阳性反应颗粒除分布在消化腔隙内独立的泡状结构上和被消化的食物组织中外,在细胞质中的小圆泡内也有分布。所得结果证实了消化腔隙和小圆泡都具有消化功能。作者推测消化腔隙主要消化食物,小圆泡则可能与自身物质(如衰老胞器等)的消化有关;并推测这种消化腔隙与小圆泡共存是纤毛虫消化胞器由食物泡演化为消化腔隙系统的中间形式。此外,在大尾柱虫纤毛内部观察到非溶酶体性的ACPase。     

棘尾虫接合生殖期间核对形态发生的影响

本文完成了四项实验,即1.促成棘尾虫无小核系与有小核系接合;2.诱导无小核系自系接合;3.在正常接合对上摘除全部大核或一个接合体的大核及小核;4.在正常接合后体上对老大核碎块和新大核胚基进行损伤实验。以改进过的黑色素法显示这些实验的结果,发现第一次接合形态发生和小核的有性过程都主要是由大核支持的,小核在第一次形态发生中也起重要作用。这些核产物可从一个有核接合体穿过细胞质桥去支持另一无核接合体的发育。本文还发现接合第二次形态发生由新大核胚基控制。损伤染色体和多线染色体时期的大核胚基,第二次形态发生消失或不正带。越过第二次形态发生的大核胚基显著增强耐受损伤的能力,这些结果符合Prescott等(1973)对棘尾虫大核遗传装置的设想。     

棘尾虫无小核镜像骈体的获得及其生殖行为的实验观察

用在分裂期进行显微手术的方法和在陈旧培养中诱导的方法,从贻贝棘尾虫天然无小核系S_(10)中获得了无小核镜像骈体。对骈体的各种生殖行为进行了观察,并用孚尔根和改进的黑色素染色技术揭示了它们的细胞学细节。发现在本文描述的无小核骈体和过去报告的有小核骈体之间,在二分裂和生理再生上没有显著区别。无小核骈体和正常单体S_7之间的接合命运则是多样化的。在630个这样的接合对中,有257对发生了真正的接合并形成接合后体;有153对接合不久包囊化;在其余的220对中,一个接合体吸收了另一个,变成营养型的单体和有小核的骈体。前者占总吸收者的96.8％,后者只占3.2％。对接合和吸收两种情况的细胞学事件进行了详细观察。无小核骈体中的两组细胞质和双套大核能吸引其配偶中的小核,形成自己新的双套大核胚基及小核胚基,在本文的讨论中受到充分注意。     

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.