林麝及马麝SRY基因片段克隆及其在系统进化分析中的应用

根据已报道的偶蹄目动物并参照人和狗SRY基因碱基序列设计一对简并引物,以林麝(Moschus berezovskii)及马麝(M．chrysogaster)基因组DNA为模板,通过PCR扩增出SRY基因CDS区。克隆的林麝及马麝SRY基因片段经测序,其长度为684bp。从父亲遗传角度出发,利用GenBank中收录的18种偶蹄目SRY基因,用邻位相接法(NJ)和最大简约法(MP)分别构建了鹿科、牛科和麝科的系统进化树。聚类树显示麝形成一个单系,支持麝作为独立一科的观点。     

基于CHD基因序列的隼形目12种鸟系统发育关系

对12个隼形目物种CHD基因的一段内含子序列进行比较和分析。CHD-W和CHD-Z基因的多态性存在差异,CHD-W基因不适合系统发生学的研究。通过对CHD-Z基因扩增序列构建的NJ和MP树,结果显示隼科鸟类与鹰科和鹳科鸟类关系较远,与传统形态分类和和鸟类新的分类系统不一致。在白腹鹞的分类地位上与传统形态学分类不一致,将白腹鹞归入鹰属一支。NJ树显示鸢属(黑鸢)与鵟属(毛脚鵟)亲缘关系较近,MP树显示鵟鹰属(灰脸鵟鹰)与鵟属(毛脚鵟)亲缘关系较近。NJ和MP树都显示雕属(金雕)和鹰雕属(鹰雕)与其他鹰科各属亲缘关系较远。     

鹿科动物线粒体控制区序列分析与系统进化

通过测定鹿科麂亚科中的小麂、赤麂和黑麂的线粒体全基因组,从而定位它们的控制区,并从GenBank获得鹿科另外3个亚科9种动物的线粒体控制区全序列。利用MEGA软件计算了各物种控制区序列的碱基组成、遗传距离和遗传相似度,通过比较序列同源性,以羊线粒体控制区序列为外群,构建NJ分子系统树,探讨了鹿科4个亚科12种动物的系统进化关系。序列分析表明,鹿科12种动物控制区序列的碱基长度在909～1049bp之间,A T含量约占62．06％,其中363个核苷酸位点存在变异(约占34％)。系统进化关系结果表明：(1)以线粒体控制区构建的鹿科12种动物分子系统树基本与NCBI分类一致;(2)美洲鹿亚科驼鹿属驼鹿在鹿科这12种动物中处于最为原始的地位;(3)小麂比赤麂和黑麂更为原始;(4)獐亚科獐属的獐与美洲鹿亚科狍鹿属的狍鹿和美洲狍鹿聚为一支。     

基于12S rRNA基因序列探讨崇安地蜥的分类地位

为探讨崇安地蜥Platyplacous sylvaticus的分类地位,测定了崇安地蜥线粒体12S rRNA基因全序列,并从GenBank中下载了东亚产10种草蜥、3种地蜥的同源序列进行分析,采用Mega V2.1软件的NJ法和ME法、PAUP4.0软件的MP法构建分子系统树.结果表明:崇安地蜥线粒体12S rRNA基因全序列(952 bp)中T、C、A、G碱基含量分别为23.1%、22.9%、35.9%、18.1%;与其它同源序列比对后有978 bp,发现321个位点出现变异,占总位点数32.8%,其中199个简约信息位点,为总变异位点的62%;转换/颠换之比平均为2.16.构建的分子系统树中,NJ树和ME树完全一致,与MP树略有差异.3种构树法中崇安地蜥与南台草蜥Takydromus sauteri、峨眉地蜥P.intermedius、先岛地蜥P.dorsalis均聚为一支,崇安地蜥与先岛地蜥亲缘关系最近.本实验结果支持将地蜥属并入草蜥属和取消地蜥亚属的观点.     

中华鳖线粒体基因组序列分析

参照近源物种线粒体基因组序列,设计17对特异引物,采用PCR产物直接测序法测得中华鳖线粒体基因组全序列.初步分析其基因组特点和各基因的定位,用pDRAW32软件预测12种限制性酶对其的酶切图谱.结果表明,中华鳖线粒体基因组全长17364bp,核苷酸组成为35.23%A、27.26%T、25.73%C、11.78%G,包括13个蛋白质编码基因、2个rRNA基因、22个tRNA基因和1个非编码控制区.基于线粒体基因组编码的13个蛋白质的氨基酸序列,用NJ法和MP法构建系统进化树,分析6种龟鳖类动物之间的亲缘关系,与传统的系统分类基本一致,初步确定淡水龟科与海龟科的亲缘关系比与龟科的亲缘关系要近.     

探讨两栖纲三个目之间的系统发生关系

现存两栖纲分为3个目,然而它们的系统发生关系仍存在较大的争议.选择Genbank上25种两栖动物线粒体全序列,结合已测定的福建大头蛙(Lim nonectes fujianensis)线粒体基因组全序列,以天鹅和眼镜凯门鳄为外群,用线粒体tRNA基因的合并数据重建系统树.采用P AU P(version 4.0b10)软件构建MP和NJ树,tree-puzzle5.2构建ML树.结果显示,NJ树和ML树以较高的自引导值支持有尾目和蚓螈目为姐妹群,而MP树则支持无尾目和有尾目为姐妹群.     

中国地鼠线粒体Cyt b基因测序及其分子进化

目的测定中国地鼠线粒体DNA细胞色素b基因部分序列,分析其分子系统进化关系。方法提取中国地鼠肝脏的总基因组DNA。设计合成特异引物进行PCR扩增,经检测进行测序。用Blast与GenBank中啮齿类其他常用实验动物的物种细胞色素b基因进行同源序列比较,分析其碱基组成及变异情况,并用邻接法、最大简约法、最小进化法构建了分子系统树,在分子水平上探讨中国地鼠和常用啮齿类实验动物的进化关系。结果获得了中国地鼠线粒体Cytb基因的部分序列,共936bp。结论中国地鼠和金黄地鼠的亲缘关系最近,与小鼠、大鼠存在的差异相对大,与豚鼠的亲缘关系最远,与传统的分类地位基本吻合。     

基于12S rRNA基因序列探讨凹耳蛙(无尾目,蛙科)的分类地位

为探讨凹耳蛙Rana tormotus的分类地位,测定了凹耳蛙线粒体12S rRNA基因序列,并从GenBank中下载了蛙科33种蛙的同源序列进行分析,用BI法、NJ法和MP法构建分子系统树.结果表明:3种树拓扑结构基本一致,都显示凹耳蛙与长吻胡湍蛙Huia nasica亲缘关系最近,凹耳蛙与长吻胡湍蛙相聚后再与臭蛙Odorrana组成单系群,而与湍蛙Amolops亲缘关系较远.据此,支持将该蛙从湍蛙属划出,并建议归入臭蛙属.     

基于CHD基因序列的18种猛禽鸟类系统发育关系

对18个猛禽CHD基因的一段内含子序列进行比较和分析.CHD-W和CHD-Z基因的多态性存在差异,CHD-W基因不适合种间系统发生学的研究.通过对CHD-Z基因扩增序列构建的NJ和ML树显示:隼科与其他猛禽物种关系较远;鹰科鸟类与鸮形目鸟类亲缘关系较近;在白腹鹞的分类地位上与传统形态学分类不一致;长耳鸮、领角鸮、花彩角鸮、西部鸣角鸮的分类地位存在分歧.鸮形目和隼形目鸟类的CHD-W基因大小有明显区别,支持形态学分类结果,与CHD-Z序列分析结果明显不同.     

基于线粒体ND4基因和核c-mos基因初步探讨广西拟水龟和艾氏拟水龟的系统发生

广西拟水龟和艾氏拟水龟的分类和系统发生多年来存在争议。通过测定广西拟水龟、艾氏拟水龟和黄喉拟水龟线粒体ND4基因和核c-mos基因部分序列,合并GenBank中拟水龟属其他物种的ND4基因和c-mos基因部分序列进行分析,从分子水平探讨广西拟水龟和艾氏拟水龟的系统发生。ND4基因数据分析发现NJ、MP和BI树中广西拟水龟与安南拟水龟的聚类分支相互交织聚为一支,二者种内遗传距离均为0.002～0.017,种间遗传距离为0.000～0.035,种间遗传距离明显小于同属内其他种间0.056～0.109的遗传距离,表明广西拟水龟与安南拟水龟可能为同一物种,可能是安南拟水龟的同种异名,或是作为安南拟水龟的一个亚种;NJ树、MP树和BI树均显示,艾氏拟水龟与黄喉拟水龟的位置和关系最为相近,二者间的遗传距离为0.020～0.035,明显小于拟水龟属其他物种间遗传距离,而明显大于同属各物种内遗传距离,艾氏拟水龟与黄喉拟水龟之间系统分类关系是介于种内与种间之间;乌龟、中华花龟、安南拟水龟等物种都是与拟水龟属中其他物种先聚成一支后再与同科的地龟属的地龟形成姐妹支,支持将乌龟属、花龟属和安南龟属并入拟水龟属的分类。c-mos基因数据分析发现,拟水龟属各物种间不存在明显的遗传距离,NJ树和MP树也未能对属中各物种的分子系统发生位置进行有效的界定,但在属及属以上阶元的分子分类系统中c-mos基因可以作为分类依据,并与线粒体基因数据有较好的一致性。     

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.