陕西渭北旱源土壤—植物—大气连续作中水分运转规律的研究──Ⅲ．生态和生理环境对叶片气孔阻力的影响

在整个生长季内,研究了陕西渭北旱源冬小麦叶气孔阻力与生态和生理因子的关系。结果表明,气孔阻力与大气温度、相对湿度和大气水势及叶温均呈二次曲线相关;与土壤水势呈直线正相关;与叶水势呈指数函数相关;当光量子通量密度小于１５２３μｍｏｌ·ｍ－２·ｓ－１时．气孔阻力与之呈幂函数相关,当光量子通量密度大于１５２３μｍｏｌ·ｍ－２·ｓ－１时,气孔阻力与之呈指数函数相关,此时气孔正处于“午休”期间。试验给出了冬小麦叶气孔阻力与各因素之间的现象模型。通过主要生态因子（气温、光量子通量密度、大气水势和相对湿度）对气孔阻力作用的综合分析表明,在陕西渭北旱塬,诸生态因子对冬小麦叶气孔阻力的重要性依次为大气水势、相对湿度、光量子通量密度和气温。并对其它影响气孔阻力的因素进行了讨论。     

陕西渭北旱塬土壤－植物－大气连续体中水分运转规律的研究──Ⅰ．生态环境对植物叶温的影响

在整个生长季内,研究了陕西省渭北旱塬主要生态因子对冬小麦叶温的影响．结果表明,叶温与气温呈直线正相关;与大气相对湿度和大气水势呈二次曲线相关;与光量子通量密度是对数正相关．并给出了冬小麦叶温与各生态因子之间的现象学模型．通过主要生态因子对叶温影响的综合分析表明,在陕西渭北旱塬,诸生态因子对冬小麦叶温的重要性依次为：大气温度、大气水势、大气相对湿度和光量子通量密度．     

陕西渭北旱塬土壤—植物—大气连续体中水分运转规律的研究…

在整个生长系内,研究了陕西省渭北旱塬生态因子对冬小麦叶温的影响。结果表明,叶温与气温呈直线一下在相关。与大气相对湿度和大气水势呈二次曲线相关;与光量子通量密度呈对数正相关。并给出了冬小麦叶温与各生态因子之间的现象学模型。     

水分胁迫下盆栽冬小麦根系生长与苗系生长及某些生理特性的关系

水分胁迫下,盆栽冬小麦根干重和根长密度呈直线正相关。鉴于根长密度反映了土壤中根系最活跃的部分［５］,是研究植物根系吸收水分和养分的最优参数之一［６］,本文用之研究了它与地上部生物量、净同化速率、叶水势和叶片相对含水量、气孔阻力和蒸腾速率的关系。结果表明,根长密度与净同化速率和地上部干重呈直线负相关,与叶水势和叶片相对含水量呈直线正相关;与气孔阻力呈直线负相关,与蒸腾速率呈直线正相关。为实验室进行冬小麦生长控制与生理特性控制提供了一定的基础。     

茶树蒸腾特性的研究

茶树蒸腾速率和气孔导度因品种、叶位不同而异．抗旱性强的品种具有低的气孔导度;鱼叶的蒸腾速率和气孔导度接近或高于真叶．茶树叶片蒸腾速率夏、秋季最高,春季次之,冬季最低．在晴天,茶树蒸腾速率和气孔导度的日变化呈单峰型,以中午前后最高;其日变化与光量子通量密度、叶温、蒸汽压亏缺等因子显著相关;光量子通量密度对蒸腾速率和气孔导度影响较明显．     

海岸沙生植物老鼠艻(Spinifex littoreus)叶水势对风蚀、沙埋和风沙流磨蚀的响应

台风是海岸地区常见的自然灾害之一,其通过风蚀、沙埋和风沙流磨蚀,严重威胁到该地区的沙生植物生长。本文以福建省平潭岛海岸典型沙生植物老鼠艻(Spinifex littoreus)为研究对象,对台风后受到风蚀、沙埋和风沙流磨蚀危害的植株叶片水势及其土壤水势和气象要素进行同步观测。结果表明:(1)老鼠艻在遭受风蚀后其受到的水分胁迫较未风蚀植株提前且强度更大,叶水势较未风蚀植株显著降低(P0.05),且与大气水势无显著相关性(P0.05)。而未风蚀时其与大气水势和相对湿度呈极显著正相关(P0.01),与气温则呈极显著负相关(P0.01);(2)沙埋后老鼠艻叶水势在10:00—16:00均高于未沙埋植株,变化幅度较小,且对气象因子响应存在滞后现象。土壤水分不足时,老鼠艻叶水势主要受土壤水势的影响,土壤水分充足时,则主要受气象因子的影响。未沙埋的老鼠艻叶水势与大气水势、相对湿度呈显著正相关(P0.05),与气温呈显著负相关(P0.05)。随着沙埋深度的增加,老鼠艻叶水势先升高后降低,适度沙埋有利于其保持较高水势以适应胁迫环境;(3)老鼠艻叶片被擦伤后,其叶水势大部分时间均低于未擦伤处理,与大气水势有一定相关性,但不显著(P0.05),而未擦伤植株叶水势则与大气水势和相对湿度呈显著正相关(P0.05),与气温呈显著负相关(P0.05)。     

遮荫条件下绞股蓝光合作用特点的研究

在夏季遮荫条件下栽培绞股蓝的净光合速率日变化呈现不典型的双峰曲线,第1峰值出现在11：00时,达13．8μmolCO2·m^-2·S^-1日净光合速率达到176．97μmol CO2·m^-2,是强光下栽培的3．1倍;净光合速率和光量子通量密度呈正相关,相对湿度对净光合速率的影响小．强光下栽培绞股蓝。光合作用“午休”现象明显,净光合速率日变化呈现双峰曲线,第1峰值出现在10：00时,为3．0μmol CO2·m^-2·s^-1．第2峰值出现在14：00时,为1．25μmol CO2·m^-2·s^-1;相对湿度与净光合速率成正相关,对净光合速率的影响大．当光量子通量超过700μmol·m^-2·s^-1时,净光合速率与光量子通量密度呈负相关．在影响该植物蒸腾速率的诸多因子中,蒸腾速率和气孔导度之间的相关性最为显著．因此绞股蓝属于高度耐荫而怕光的植物．人工栽培应重点考虑光照因子．     

几个猕猴桃品种净光合速率和蒸腾速率与环境因素的关系

依据田间试验资料,建立了３个猕猴桃品种的净光合速率和蒸腾速率与环境因素（空气温度、光量子通量密度、空气相对湿度）的经验公式;比较了３个品种对环境适应能力上的差异,在育种工作中,为选择具有理想生理特性的品种和确定品种适生区等提供生理学依据。研究表明美味猕猴桃的生理活动对空气湿度变化反应强烈,当光量子能量密度为３００－３５００μｍｏｌ·ｍ＾－２·ｓ＾－１,气温为３２－３５℃时最适合其生理活动。相对于秦     

福建平潭岛海岸不同演化阶段草丛沙堆表面老鼠艻叶水势日变化特征

以福建省平潭岛海岸不同演化阶段草丛沙堆表面典型沙生植物老鼠艻为对象,研究其叶水势日变化特征及其影响因素.结果表明: 老鼠艻叶水势日变化以“W”型为主,午间出现短暂升高现象.发育阶段沙堆表面老鼠艻叶水势日均值较稳定阶段高,且夜间水分恢复能力更强;老鼠艻叶水势与大气水势和相对湿度呈显著正相关,与气温呈显著负相关,但与不同深度土壤水势无显著相关性;发育阶段沙堆丘间地老鼠艻叶水势在10:00—16:00皆高于迎风坡和背风坡,迎风坡除10:00和12:00外皆低于背风坡.不同坡位叶水势日变异程度表现为背风坡>迎风坡>丘间地,但无显著差异.沙堆迎风坡老鼠艻叶水势与大气水势和相对湿度呈显著正相关,与气温呈显著负相关;沙堆背风坡和丘间地老鼠艻叶水势与气象因子有一定相关性,但不显著.     

曼地亚红豆杉蒸腾速率日变化及因子分析

应用LI-1600 稳态气孔计对曼地亚红豆杉(Taxus media cv.Hicksii)叶片的蒸腾速率、气孔阻力和几个生态因子的日变化同步进行了测定。并采用多元回归分析和灰色关联度分析的方法探讨了曼地亚红豆杉叶片蒸腾速率与影响因子的关系, 结果表明:影响曼地亚红豆杉蒸腾速率的主要因子是叶温、气温;其次是光量子通量密度、空气相对湿度、气孔阻力。灰色关联度分析与多元回归分析结论基本一致。对曼地亚红豆杉叶片蒸腾速率与气孔阻力的相关关系分析表明:蒸腾速率和气孔阻力间属非线性关系, 其方程为:Tr=12.789-13.419 lg Rs(R²=0.971 7)     

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.