毛竹APX基因系统进化与表达分析

抗坏血酸过氧化物酶(aseorbate peroxidase, APX)是植物活性氧代谢中重要的抗氧化酶之一,尤其是叶绿体中清除H₂O₂的关键酶,也是维生素C代谢的主要酶类。该文基于生物信息学方法,利用毛竹的基因组及转录组数据鉴定毛竹中的APX基因家族成员,并对其编码的蛋白基本理化性质、基因结构、启动子元件、系统进化及共线性关系、重复串联基因、GO注释及表达模式进行综合分析,共鉴定出21种编码APX的基因。结果表明:(1)PeAPX基因家族成员多为不稳定疏水蛋白,基因结构、基序及结构域相对较为保守,大多数APX基因具有高度保守的内含子模式。(2)系统进化关系显示毛竹APX基因与水稻APX基因有着较高的同源性关系,PeAPX具有较高的进化保守性。(3)Ka/Ks分析表明PeAPX基因都经历了纯化选择压力,此外在每个APX基因的启动子序列中发现有许多与应激反应和植物激素相关的顺式作用元件,结合表达量分析,表明毛竹APX基因在毛竹生长发育中起着正向促进作用。该研究为进一步了解毛竹APX基因家族基本功能及其抗氧化机制提供了一定的参考,为毛竹APX基因功能的深层次鉴定提供了重要依据。     

非洲菊4个POD基因的克隆及表达分析

以‘玲珑’非洲菊为材料,利用RT PCR技术克隆获得4个POD基因,分别命名为GjPOD4、GjPOD5、GjPOD7和GjPOD42（GenBank登录号分别为MH708528、MH708531、MH708529和MH708530）。对这4个基因进行生物信息学分析,并分析在SA、干旱、低温胁迫和非洲菊根腐病病原菌胁迫下4个POD基因的表达模式以及POD活性的变化特征,为揭示非洲菊POD基因的功能以及抗性育种奠定基础。结果显示：（1）所克隆的4个POD基因的cDNA长度为966~1 005 bp,编码321~334个氨基酸;生物信息学分析发现,它们编码的蛋白均属于植物亚铁红素依赖Ⅲ型POD,含有保守结构域及Motif,含有信号肽、跨膜螺旋结构和磷酸化位点。（2）进化树分析结果表明,GjPOD4和GjPOD7与拟南芥AtPRX52、GjPOD5与AtPRX47、GjPOD42与AtPRX42亲缘关系较近。（3）SA、干旱、低温胁迫和非洲菊根腐病病原菌处理均可显著或极显著影响4个基因的表达以及POD活性,但GjPOD4与其他3个GjPOD基因的表达趋势存在一定的差异。（4）相关性分析显示,在不同器官中,GjPOD42的表达与POD活性均呈显著正相关关系（P<0.05）;在隐地疫霉处理下, 4个POD基因表达均极显著上调且与POD活性呈正相关关系。研究表明,所克隆的 4个POD基因在非洲菊抗逆防御过程中,尤其是在响应隐地疫霉侵染过程中发挥着重要作用,但GjPOD4与其他3个GjPOD存在一定的功能差异。     

外源5-氨基乙酰丙酸对盐胁迫下菘蓝种子萌发及幼苗抗氧化酶活性的影响

采用砂培方式,研究了外源5-氨基乙酰丙酸(ALA)对盐胁迫下菘蓝种子的萌发、幼苗叶片的可溶性糖含量、丙二醛(MDA)含量及其抗氧化酶活性的影响,探讨ALA缓解菘蓝受盐胁迫伤害的响应机制。结果显示:(1)菘蓝种子萌发及幼苗生长在100 mmol·L^-1 NaCl胁迫下受到明显的抑制,种子发芽率、发芽势、发芽指数、活力指数与自然含水量均显著降低,丙二醛含量、可溶性糖含量以及超氧化物歧化酶(SOD)、过氧化物酶(POD)活性显著升高。(2)盐胁迫下适宜浓度的ALA处理显著提高了种子萌发率、自然含水量及SOD、POD和CAT活性,降低了可溶性糖和丙二醛的含量,并以16.7 mg·L^-1 ALA处理盐胁迫下菘蓝种子的发芽率、发芽势最大,其幼苗的SOD、POD、CAT活性最强。研究表明,盐胁迫显著抑制菘蓝种子的萌发及幼苗生长,适宜浓度的ALA能够有效缓解盐胁迫对菘蓝种子萌发及幼苗生长的伤害,提高植株的抗盐性,并以16.7 mg·L^-1 ALA处理效果最佳。     

出芽酵母Saccharomyces cerevisiae转录抑制因子Rdr1负调控细胞胁迫应答

Rdr1是出芽酵母Saccharomyces cerevisiae的一个转录抑制因子,参与控制细胞的多重药物耐受性,并可能与细胞胁迫应答相关．利用PCR方法扩增RDR1基因片段,将其克隆至高拷贝表达载体pYES2/NTA上并诱导Rdr1蛋白在酵母细胞中过表达．为了揭示转录抑制因子Rdr1在胁迫应答中的作用,比较了RDR1过表达细胞、RDR1缺失突变体细胞和野生型细胞在过氧化氢处理、热胁迫和高盐处理条件下的生长状态,结果显示,RDR1过表达导致细胞对上述3种胁迫作用更敏感,而RDR1缺失则使细胞对这些胁迫作用的耐受性不受影响或有一定增强．为了揭示上述不同细胞在胁迫条件下生长状态的差异与细胞内抗氧化酶活性之间的关系,测定并比较了RDR1过表达细胞、RDR1缺失突变体细胞和野生型细胞中超氧化物岐化酶(superoxide dismutase SOD)、过氧化氢酶、葡萄糖-6-磷酸脱氢酶(glucose-6-phosphate dehydrogenase G6PDH)、谷胱甘肽还原酶(glutathione reductase GR)的活性．结果表明,RDR1缺失突变体细胞具高活性的SOD、过氧化氢酶、G6PDH和GR,而Rdr1过表达细胞中SOD、过氧化氢酶、G6PDH和GR的活性较低．RDR1对SOD和过氧化氢酶活性的影响要大于G6PDH和GR．细胞抗氧化酶活性的变化初步揭示,RDR1过表达细胞对胁迫的敏感和RDR1缺失突变体细胞对胁迫耐受性增加的原因．为转录抑制因子Rdr1在胁迫应答中的负调控作用及其机理提供了初步的遗传学和生物化学证据．     

古莲子与现代莲子ABA含量和SOD活性的比较研究

本研究选用种龄为 580± 70年的古莲子──太子莲 ,和与之亲缘相近的种龄为 8年的现代哈尔滨莲 ,对比测定其脱落酸的含量及超氧物歧化酶活性 ,以期探讨距今已有几百年种龄的古莲仍能保持其活力、萌发、开花的现象与这两项生理指标的关系。实验结果表明 ,两种莲子的皮 (果皮和种皮 )ABA含量均很高 ,太子莲和哈尔滨莲分别为 4.1 8μg/g ,5.69μg/g。SOD活性在莲子吸胀期和幼苗期两种莲子的子叶中差异不明显 ,而在胚和幼芽中 ,太子莲比哈尔滨莲分别高出 50 %和 2 7%。基于以上结果 ,说明其胚中具有较强的抗逆性物质 ,利于保持其生命力。莲皮中高含量的ABA及胚中高活性的SOD有利于莲子的休眠和增强其抗逆性 ,并保持胚的生命力     

盐胁迫下赤霉素对黄瓜种子萌发及幼苗生长的影响

研究外源GA₃对盐胁迫下黄瓜种子萌发和幼苗生长的影响。结果表明,添加不同质量浓度GA₃的各处理,其发芽率、发芽势和发芽指数均显著高于NaCl胁迫处理,其中以100 mg/L GA₃处理的发芽势、发芽率和发芽指数最高,幼苗的叶面积、根长、根冠比也最大,同时叶片中叶绿素含量最高,幼苗叶片的光合速率(P_n)、气孔导度(G_s)、胞间CO₂摩尔分数(C_i)及蒸腾速率(T_r)等均达到最大;而当赤霉素的质量浓度为50 mg/L时,叶片中的POD活性为2 005 U/(g·min）,达最大值。     

不同温度条件下PEG模拟干旱胁迫对水杉种子萌发的影响

水杉原生种群天然更新极差,林下鲜见幼苗和幼树,种子萌发率低是造成天然更新困难的重要因素。为探究其种子萌发率低是否与水杉母树原生地春季低温有关,该文利用恒温培养箱设置3种恒温处理(15、20、25 ℃)和1种变温处理(12 ℃/12 h和24 ℃/12 h,每24 h交替),并设置5种不同浓度的聚乙二醇(PEG-6000,0、0.05、0.10、0.15、0.20 g·mL^-1)模拟干旱胁迫,来研究干旱胁迫对水杉种子萌发的影响。结果表明:(1)实验所设置的温度对水杉种子萌发无显著影响(P>0.05),变温条件下的水杉种子平均发芽率和发芽势均为最高,分别为46.75%和21.25%;(2)不同浓度的PEG-6000溶液对其种子萌发产生显著影响(P<0.05),水杉在15 ℃或25 ℃下,低浓度的PEG-6000溶液(0～0.10 g·mL^-1)对水杉种子的发芽势和发芽指数有促进作用,高浓度(>0.10 g·mL^-1)的PEG-6000溶液对水杉种子的萌发有抑制作用,且随着浓度的增大抑制作用也随之增强,直到浓度增大为0.20 g·mL^-1 时,水杉种子不再萌发。原生地春季低温并不是造成水杉原生种群天然更新困难的因素,适当的干旱胁迫有利于增强水杉种子发芽势和发芽指数,促使出苗整齐。     

古莲子与现代莲子ABA含量和SOD活性的比较研究

本研究选用种龄为580±70年的古莲子──太子莲,和与之亲缘相近的种龄为8年的现代哈尔滨莲,对比测定其脱落酸的含量及超氧物歧化酶活性,以期探讨距今已有几百年种龄的古莲仍能保持其活力、萌发、开花的现象与这两项生理指标的关系。实验结果表明,两种莲子的皮（果皮和种皮）ABA含量均很高,太子莲和哈尔滨莲分别为4.18 μg/g, 5.69 μg/g。SOD活性在莲子吸胀期和幼苗期两种莲子的子叶中差异不明显,而在胚和幼芽中,太子莲比哈尔滨莲分别高出50%和27%。基于以上结果,说明其胚中具有较强的抗逆性物质,利于保持其生命力。莲皮中高含量的ABA及胚中高活性的SOD有利于莲子的休眠和增强其抗逆性,并保持胚的生命力。     

核桃JrsHSP17.3基因克隆及温度胁迫响应模式分析

通过分析核桃（Juglans regia）转录组,鉴定获得核桃热激蛋白家族sHSP17.3基因的全长cDNA序列,命名为JrsHSP17.3。JrsHSP17.3基因开放读码框474 bp,编码产物含157个氨基酸,分子量为17.64 kD,理论等电点为5.35。为了研究该基因表达的组织特异性及温度响应模式,采用实时荧光定量PCR（qRT-PCR）方法,对高温和低温胁迫下JrsHSP17.3基因在根、茎、叶中的转录水平进行分析。结果显示,JrsHSP17.3基因在不同组织中均有表达;经高温（36 ℃～52 ℃）和低温（16 ℃～6 ℃）处理后,JrsHSP17.3基因均可被显著诱导,其中12 ℃胁迫1 h表达最高,为对照（非处理情况）的142.02倍。研究表明核桃JrsHSP17.3基因能够响应冷热温度胁迫,为进一步研究JrsHSP17.3基因的抗寒耐高温特性奠定基础。     

盐和重金属复合胁迫对翅碱蓬萌发与生长的影响及调控措施

为探究Zn、Cu与盐复合胁迫对翅碱蓬(Suaeda salsa)萌发生长的影响机理及其调控措施,以翅碱蓬为研究对象,采用水培试验方法,测定Zn、Cu和盐复合胁迫条件下翅碱蓬种子发芽率、萌发速率和幼苗渗透调节物质含量等指标,分析1.5 mg/L吲哚乙酸(IAA)、100 mg/L赤霉素(GA)和0.3%硝酸钾(KNO₃)处理对Zn、Cu与盐复合胁迫条件下翅碱蓬萌发与生长的影响。结果表明：(1) Zn、Cu与高盐复合胁迫极显著降低翅碱蓬种子的发芽率,中高浓度的Zn、Cu与盐复合胁迫极显著降低翅碱蓬种子的萌发速率,Zn、Cu和盐复合胁迫对翅碱蓬种子的萌发生长影响表现为低促高抑效应,影响因子间存在明显的协同效应;(2)Zn、Cu和盐复合胁迫条件下,随着盐浓度的升高,翅碱蓬幼苗体内过氧化氢酶(CAT)、过氧化物酶(POD)和超氧化物歧化酶(SOD)3种抗氧化酶活性呈先升高后降低的变化趋势,Zn、Cu和高盐复合胁迫使翅碱蓬幼苗体内丙二醛(MDA)含量增加近2.5倍;(3)1.5 mg/L IAA溶液浸种12 h可显著提高Zn、Cu与高盐复合胁迫条件下翅碱蓬种子的发芽率和萌发速...     

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.