亚精胺浸种对番茄幼苗抗盐碱的生理特性研究

以番茄耐盐碱品种‘金鹏一号’和盐碱敏感品种‘中杂9号’为试验材料,采用营养液水培的方法,设置正常营养液栽培(对照CK)、100mmol/L盐碱溶液胁迫、100mmol/L盐碱溶液胁迫+0.1mmol/L亚精胺(Spd)浸种、100mmol/L盐碱溶液胁迫+0.25mmol/L Spd浸种4种处理,研究外源Spd对番茄幼苗株高和茎粗的相对生长率、叶片和根系含水量、超氧化物歧化酶(SOD)和过氧化物酶(POD)活性以及丙二醛(MDA)、脯氨酸(Pro)、叶绿素含量的影响。结果显示:(1)单独盐碱胁迫下,两品种番茄幼苗叶绿素含量、株高和茎粗的相对生长率、叶片和根系相对含水量较对照均降低,而其MDA、Pro含量、SOD和POD活性显著增加。(2)外源Spd浸种处理较盐碱胁迫下能够增加番茄幼苗的株高和茎粗的相对生长率、叶片和根系的相对含水量、Pro及叶绿素含量,进一步提高SOD和POD的活性,降低其MDA含量,能有效缓解盐碱胁迫对番茄幼苗的伤害。(3)在100mmol/L盐碱胁迫条件下,0.25mmol/L Spd浸种处理对番茄幼苗受到的盐碱胁迫伤害的缓解效果更佳,并且这种缓解作用对盐碱敏感品种‘中杂9号’幼苗的效果更加明显。研究表明,在盐碱胁迫下,番茄幼苗的生长受到一定程度的抑制,但外源Spd浸种能够通过调节渗透调节物质含量、增强抗氧化酶活性来减轻盐碱胁迫的伤害,维持植物体的正常生理代谢功能,从而提高番茄幼苗抵抗盐碱胁迫能力,有效缓解盐碱胁迫的伤害,并以0.25mmol/L Spd浸种处理缓解效果更佳,且这种缓解作用对盐碱敏感品种‘中杂9号’幼苗效果更明显。     

NaCl胁迫下亚精胺对番茄种子萌发及幼苗抗氧化系统的影响

采用盆栽试验,研究了NaCl胁迫下外源亚精胺（Spd）浸种处理对“白果强丰”番茄种子萌发、幼苗生长及叶片抗氧化系统的影响.结果表明：Spd浸种处理的番茄种子发芽率（G_r）、发芽指数（G_i）和活力指数（V_i）均显著增加,分别比单纯NaCl处理增加了104.90%、142.31%和122.22%,而番茄种子的平均发芽时间（MGT）缩短了4.97%;Spd浸种处理提高了NaCl胁迫下番茄幼苗叶片超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）活性,降低了O₂^-·产生速率和过氧化氢（H₂O₂）含量,进而降低了丙二醛（MDA）含量和质膜电解质渗漏率,增加了叶片可溶性蛋白质含量,促进了番茄幼苗生长.表明Spd浸种促进了NaCl胁迫下番茄种子的萌发及幼苗生长,增强了植株的抗盐性.     

外源Ca(NO_3)_2对NaCl胁迫下番茄幼苗生理特征的影响

以番茄品种'农城906'和"毛粉802'幼苗为材料,利用Hoagland基础培养液,研究在150 mmol/L NaCl胁迫下外源10、20、30和40 mmol/L Ca(NO3)2对番茄植株盐胁迫的缓解作用.结果显示,(1) NaCl胁迫显著降低了2个品种幼苗地上和地下部分干重、叶片叶绿素含量和根系活力,增加了幼苗的可溶性糖含量、细胞膜透性和MDA含量,同时使其CAT、POD、SOD活性显著降低;(2)添加20 mmol/L Ca(NO3)2能够有效提高盐胁迫条件下幼苗的地上和地下部干重,缓解叶绿素的降解和根系活力的下降,增加幼苗体内可溶性糖含量,降低叶片质膜透性和MDA含量,增强幼苗体内POD、CAT等细胞保护酶活性,但随着Ca(NO3)2浓度的继续增加,这种缓解作用逐渐减小.研究表明,一定浓度的外源Ca(NO3)2能有效缓解NaCl对番茄幼苗的生长和生理伤害,在一定程度上增强番茄幼苗对盐胁迫的耐受力,并以20 mmol/L Ca(NO3)2对NaCl胁迫的缓解效果最佳.     

外源亚精胺对盐胁迫下白刺幼苗叶片抗氧化酶系统的影响

为进一步阐明盐生植物白刺耐盐性与多胺的关系,通过水培试验研究了叶面喷施亚精胺(Spd)对不同浓度NaCl胁迫下西伯利亚白刺幼苗叶片丙二醛(MDA)和超氧阴离子(O2)产生速率,以及抗氧化物酶系统和根系活力的影响.结果表明:叶面喷施0.1 mmol·L1 Spd 5 d后,可显著提高100和200 mmol·L1 NaCl胁迫下白刺幼苗叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)的活性以及根系活力,降低了叶片MDA含量和O2的产生速率;而在0、50、300 mmol·L-1 NaC1处理下,外施Spd对白刺幼苗叶片上述指标无显著影响.研究结果证实,在100～200 mmol·L-1 NaCl胁迫范围内,外施亚精胺可能通过增强体内保护酶活性来显著降低活性氧水平,有效减轻盐胁迫对盐生植物白刺幼苗造成的过氧化伤害,从而增强白刺对盐环境的适应性.     

外源亚精胺对盐胁迫下燕麦幼苗生长及生理特性的影响

为探讨外源喷施亚精胺(Spd)对燕麦幼苗生长和耐盐性的影响,该研究选用燕麦品种‘白燕5号’为试验材料,通过水培试验研究70 mmol/L盐胁迫下(NaCl和Na_2SO_4摩尔比1∶1混合),叶面喷施不同浓度的亚精胺对燕麦幼苗生长、根系活力、抗氧化酶活性以及丙二醛、游离脯氨酸和离子含量的影响。结果显示:(1)盐胁迫显著抑制了燕麦幼苗生长,喷施0.75 mmol/L Spd使盐胁迫下幼苗地上、地下干重和根系活力分别显著提高34.1%、23.8%和24.7%。(2)喷施0.75 mmol/L Spd使幼苗叶片中超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)的活性较对照分别显著增加了17.0%、22.9%和23.7%,根系中分别显著增加了43.0%、19.4%和91.2%,并使幼苗叶片和根系中的MDA含量分别显著降低了25.2%和12.8%。(3)喷施0.75 mmol/L Spd使燕麦幼苗叶片和根系游离脯氨酸(Pro)含量分别显著增加了63.3%和362.6%,并使叶片Na~+/K~+、Na~+/Ca~(2+)和Na~+/Mg~(2+)值分别降低了6.7%、16.3%和4.9%。研究表明,在盐胁迫环境下,叶面喷施适宜浓度(0.75 mmol/L) Spd可通过提高燕麦幼苗抗氧化和渗透调节能力,维持生物膜系统的稳定,有效减轻渗透胁迫和离子毒害对幼苗的伤害,从而增强其耐盐性,促进幼苗生长。     

多胺浸种改善盐胁迫大麦根系液泡膜功能的机理

研究了0.1 mmol/L 腐胺 (Put) 和0.5 mmol/L 亚精胺 (Spd) 浸种对200 mmol/L NaCl胁迫下大麦(Hordeum vulgare L.)幼苗生长速率、干物质积累、离子分布、液泡膜蛋白结合多胺含量以及液泡膜膜脂组分与功能的影响.结果表明,Put和Spd浸种均可缓解盐胁迫对大麦幼苗的盐害,促进生长和干物质积累,降低大麦幼苗体内[Na+]/[K+].与盐处理的对照植株相比,Put和Spd浸种均可提高大麦幼苗根系液泡膜磷脂含量,降低糖脂结合半乳糖含量,而膜上非共价结合多胺含量Spd+PAx (一种未知多胺) 与 Put+Dap (二氨基丙烷)之比((Spd+PAx)/(Put+Dap))、共价和非共价结合多胺总量均上升.统计分析结果表明,液泡膜非共价结合多胺(Spd+PAx)/(Put+Dap)与H+-ATPase和H+-PPase活性呈显著正相关关系.     

γ-氨基丁酸浸种对番茄种子及幼苗耐盐性调节的生理机制

以番茄‘金棚一号’为材料,研究了外源γ-氨基丁酸(GABA)浸种处理对NaCl胁迫下种子萌发及幼苗生长和生理代谢的影响。结果显示:(1)NaCl胁迫显著抑制了番茄种子的萌发和胚根生长,同时导致番茄幼苗体内活性氧(O2.-、H2O2)大量积累,膜脂过氧化程度加重,幼苗叶片光合系统Ⅱ活性显著降低,幼苗的生长受到严重抑制。(2)外源GABA浸种能够显著提高盐胁迫下番茄种子的萌发和胚根的生长,并以10.00mmol.L-1 GABA浸种处理效果最好。(3)外源GABA浸种处理显著提高了NaCl胁迫下番茄幼苗根系和叶片抗氧化酶(SOD、POD和CAT)活性,降低了活性氧(O2.-、H2O2)的产生和膜脂过氧化程度,通过维持较高的光合系统Ⅱ活性,促进了幼苗的生长及生物量积累,但GABA的缓解效应存在较大的浓度差异,其中以10.00mmol.L-1 GABA处理效果较好。研究表明,10.00mmol.L-1 GABA浸种处理能够通过促进番茄种子萌发和幼苗生长来缓解盐胁迫的伤害。     

盐胁迫对海岛棉不同基因型幼苗生长及生理生态特征的影响

采用水培试验,分析了不同浓度的NaCl(0、50、100、150、200、250 mmol.L-1)处理对两个海岛棉品种新海28号(XH28,耐盐基因型)和新海21号(XH21,盐敏感基因型)植株生长、生物量分配、蛋白质含量、脯氨酸(Pro)含量以及过氧化物酶(POD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)、谷胱甘肽还原酶(GR)等生理生态指标的影响。研究发现:(1)盐胁迫对海岛棉幼苗鲜重的影响大于干重,对茎叶的影响大于根系;(2)盐处理引起海岛棉幼苗根叶脯氨酸含量的增加;(3)低浓度NaCl处理(≤50 mmol.L-1)显著增加耐盐品种XH28的根长、株高及单株鲜干重;(4)盐胁迫引起海岛棉幼苗根系中可溶性蛋白质含量下降,相反叶片中可溶性蛋白质含量上升;(5)盐胁迫下耐盐品种XH28幼苗中的POD、CAT、APX酶活性明显高于盐敏感品种XH21,但GR活性显著低于XH21。研究表明,低浓度NaCl处理刺激了棉株生长,增加了生物量;盐胁迫下叶内蛋白质、脯氨酸含量明显增加,POD、CAT、APX酶活力升高是海岛棉耐盐品种XH28的基本特征。     

盐胁迫对冬小麦幼苗干物质分配和生理生态特性的影响

以冬小麦(Triticum aestivum L.)品种周麦18(Zhoumai18)和豫麦49(Yumai49)为材料,采用盆栽培养,研究100、250、350 mmol/L和450 mmol/L NaCl 浓度胁迫下,小麦幼苗干物质分配、根系特征、叶绿素含量、游离脯氨酸含量和根系活力变化规律.结果表明,随着盐分浓度的增加,两个品种小麦的叶面积、地上干重以及根的长度显著减小;根系干重、根直径、根表面积、根体积、根系活力以及叶绿素含量呈先上升后下降趋势,在250 mmol/L NaCl处理下达最大.叶绿素a/b随NaCl浓度升高而上升.随盐分浓度变化周麦18叶片游离脯氨酸含量高而变化幅度大,450mmol/L处理组的含量高于对照组1.5倍.供试品种冬小麦耐盐阈值为250～350 mmol/L.     

NaCl胁迫对结荚期菜用大豆叶片游离态多胺水平的影响

采用蛭石栽培,在100mmol·L-1NaCl胁迫下,对耐盐性不同的2个菜用大豆[Glycinemax(L.)Merr.]品种结荚期干物质积累、单株产量及叶片游离态多胺(PAs)水平的变化进行了研究。结果表明:NaCl胁迫显著降低了菜用大豆植株干重及单株产量,但耐盐品种"绿领特早"的降幅低于盐敏感品种"理想高产95-1";与"理想高产95-1"相比,"绿领特早"叶片在整个NaCl胁迫期间均维持了相对较低的H2O2含量、游离态腐胺(Put)含量及较高的游离态亚精胺(Spd)含量,在胁迫6～15d期间维持了相对较高的游离态精胺(Spm)含量、(Spd+Spm)/Put值及较低的Put/PAs值。说明耐盐品种"绿领特早"叶片具有较强的由游离态Put向游离态Spd和Spm转化的能力,维持了较低的游离态Put含量和较高的游离态Spd及Spm含量,进而抑制了活性氧过量积累。     

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.