Narciclasine与植物激素的相互作用研究

主要研究了天然生物活性物质Narciclasine(NCS)与植物激素的相互作用。发现NCS对于IAA刺激小麦胚芽鞘伸长过程、GA3对大麦胚乳中α-淀粉两诱导作用及6-BA对离体萝卜子叶光下增大以及转绿过程的促进作用,均显示出一定的抑制作用,而且其抑制强度均随浓度的增加而增加。对于不同的生理过程,NCS表现出不同的抑制强度,其中对离体萝卜子叶光下转绿过程的抑制作用较强。对于离体子叶的光下增大和转绿过程,不同植物激素的表现不同,6-BA和GA3对离体子叶增大及光下转绿具有促进作用;ABA和NCS则显示出一定的抑制作用。     

NCS对离体萝卜子叶微体中酶活性及细胞超微结构的影响

研究了天然生物活性物质narciclasine(NCS)对离体萝卜子叶光下生长发育期间叶绿素含量变化、异柠檬酸裂解酶及羟基丙酮酸还原酶活性的影响;并对萝卜子叶细胞的超微结构变化进行了观察。结果表明,NCS明显抑制光下培养的离体萝卜子叶叶绿素含量及鲜重增加,对异柠檬酸裂解酶及羟基丙酮酸还原酶活性也显示出明显的抑制作用。电镜观察显示,NCS对蛋白体及脂质体的降解、叶绿体的发育也表现出强烈的抑制效应。NCS的各种抑制作用均随其浓度的增加而增加,而且高浓度的NCS(10^-5mol／L)基本上完全阻止了离体萝卜子叶的光下生长及其转绿。     

NaCl胁迫加重强光胁迫下超大甜椒叶片的光系统Ⅱ和光系统Ⅰ的光抑制

快速叶绿素荧光动力学可以在无损情况下探知叶片光合机构的损伤程度,快速叶绿素荧光测定和分析技术(JIP-test)将测量值转化为多种具有生物学意义的参数,因而被广泛应用于植物光合机构对环境的响应机制研究.该文研究了超大甜椒(Capsicum annuum)幼苗在强光及不同NaCl浓度胁迫下的荧光响应情况.与单纯强光胁迫相比,NaCl胁迫引起了叶绿素荧光诱导曲线的明显改变,光系统Ⅱ(PSⅡ)光抑制加重,同时PSⅡ反应中心和受体侧受到明显影响,而且高NaCl浓度胁迫下PSⅡ供体侧受伤害明显,同时PSⅠ反应中心活性(P700+)在盐胁迫下明显降低.这些结果表明,NaCl胁迫会增强强光对超大甜椒光系统的光抑制,并且浓度越高抑制越明显,但对PSⅠ的抑制作用低于PSⅡ.高NaCl浓度胁迫易对PSⅡ供体侧造成破坏,且PSⅠ光抑制严重.     

经济海藻红毛菜原位光合作用日变化

利用光合气体交换和叶绿素a荧光技术测定了原位沉水和干出条件下红毛菜光合作用的日变化,结果显示与沉水藻体相比,中午干出藻体光合速率、光系统II最大光化学效率(Fv/Fm)、实际光化学效率(ΦPSⅡ)、光化学淬灭系数(qP),光响应曲线初始斜率(ɑETR)和相对电子传递速率(rETR)值下降更明显。干出藻体重新入水后,其叶绿素a荧光参数在两个小时内可以完全恢复到沉水藻体的水平。红毛菜叶绿素a、类胡萝卜素、藻红蛋白的含量在一天中并没有出现明显变化。以上结果表明红毛菜日生长在中午要经历光抑制过程,干出状态下光抑制更严重;干出和沉水藻体光合速率都可以在傍晚得以恢复;红毛菜光系统II反应中心可以通过增加热耗散和降低光合电子传递速率等策略来应对光抑制。     

复苏被子植物牛耳草脱水和复水期间叶黄素循环的保护作用

研究了复苏被子植物牛耳草(Boea hygrometrica (Bunge) R.Br.)离体叶片在微弱光强下(3 μmol photons*m-2*s-1)和黑暗中叶黄素循环组分及叶绿素荧光随脱水复水的变化.结果发现:脱水期间随着光系统Ⅱ光化学效率(Fv/Fm)、实际量子产率(ΦPSⅡ)、光化学淬灭(qP)和非光化学淬灭(NPQ)值的降低,微弱光强下的对照叶片玉米黄素含量显著增加,而微弱光强下DTT处理的叶片和黑暗中的叶片都没有玉米黄素的积累.经过3 d复水后,微弱光强下对照叶片的Fv/Fm, ΦPSⅡ, qP 和 NPQ值能完全恢复,但是微弱光强下DTT处理的叶片和黑暗中的叶片其Fv/Fm、ΦPSⅡ、qP 和 NPQ值只有部分恢复.说明脱水的牛耳草离体叶片光系统Ⅱ的光化学活性的恢复明显受到DTT处理和黑暗的影响,因此玉米黄素可能对微弱光强下脱水的牛耳草叶片具有重要的保护作用.     

缺铁对大豆叶片光合作用和光系统Ⅱ功能的影响

通过气体交换和叶绿素荧光测定研究了缺铁对大豆叶片碳同化和光系统Ⅱ的影响。缺铁条件下大豆光合速率(Pn)大幅下降;最大光化学效率(po)下降幅度较小;荧光诱导动力学曲线发生明显的变化,其中电子传递活性明显下降,K相(VK)相对荧光产量提高。缺铁大豆的天线转化效率(Fv'/Fm')、光化学猝灭系数(qP)和光系统Ⅱ实际光化学效率(ΦPSⅡ)降低,而非光化学猝灭(NPQ)则明显增加。此外,缺铁大豆的光后荧光上升增强。据此,认为铁缺乏伤害了光系统Ⅱ复合物供体侧和受体侧的电子传递;缺铁条件下光系统I环式电子传递的增强可能在维持激发能耗散和ATP供给方面起一定作用。     

NaCl胁迫加重强光胁迫下超大甜椒叶片的光系统II和光系统I的光抑制

快速叶绿素荧光动力学可以在无损情况下探知叶片光合机构的损伤程度, 快速叶绿素荧光测定和分析技术(JIP-test)将测量值转化为多种具有生物学意义的参数, 因而被广泛应用于植物光合机构对环境的响应机制研究。该文研究了超大甜椒(Capsicum annuum)幼苗在强光及不同NaCl浓度胁迫下的荧光响应情况。与单纯强光胁迫相比, NaCl胁迫引起了叶绿素荧光诱导曲线的明显改变, 光系统II (PSII)光抑制加重, 同时PSII反应中心和受体侧受到明显影响, 而且高NaCl浓度胁迫下PSII供体侧受伤害明显, 同时PSI反应中心活性(P700⁺)在盐胁迫下明显降低。这些结果表明, NaCl胁迫会增强强光对超大甜椒光系统的光抑制, 并且浓度越高抑制越明显, 但对PSI的抑制作用低于PSII。高NaCl浓度胁迫易对PSII供体侧造成破坏, 且PSI光抑制严重。     

NaCl胁迫对马齿苋光合作用及叶绿素荧光特性的影响

以马齿苋为材料,采用温室盆栽法研究了14 d NaCl胁迫处理对其幼苗生长、光合作用和叶绿素荧光特性的影响.结果显示:(1)马齿苋幼苗的鲜重和株高在25 mmol·L-1 NaCl胁迫时与对照无显著差异,但其随着NaCl浓度的继续增加均显著降低,且其生物量受到的抑制早于株高.(2) NaCl胁迫下,马齿苋幼苗叶片净光合速率(Pn)降低,胞间二氧化碳浓度(C1)增大,且两者的变化幅度随着NaCl浓度增加而增大.(3)NaCl胁迫下,马齿苋幼苗叶片的初始荧光(F0)、最大荧光(Fm)、可变荧光(Fv)、恒态荧光(Fs)、恒态荧光与初始荧光差值(△F0)、PSⅡ潜在光化学效率(Fv/Fo)和PSⅡ最大光化学效率(Fv/Fm)均降低,叶片光化学荧光猝灭系数(qP)也在NaCl胁迫下降低,而非光化学荧光猝灭系数(NPQ)则上升;在0～50 mmol·L-1NaCl胁迫下,幼苗叶片各荧光参数下降幅度小于其他高浓度NaCl胁迫.研究表明,在NaCl胁迫条件下,马齿苋幼苗叶片的光合作用受光抑制伤害,但在低浓度NaCl下能够较多地将光能用于光化学反应,光抑制程度较低,保持了较高的净光合速率,明显减轻盐胁迫对植株生长的影响,表现出一定的耐盐性.     

逆境胁迫对菜豆黄化苗转绿过程中交替呼吸途径与叶绿素荧光特征的影响

以菜豆黄化幼苗作为试验材料,探讨了铅(Pb)或PEG(聚乙二醇)胁迫下交替呼吸途径在植物转绿过程中对叶绿素含量以及叶绿素荧光特性的影响,以阐明逆境胁迫下植物交替呼吸途径的生理学作用。结果显示：(1)与菜豆黄化幼苗正常转绿过程(对照)相比,Pb或PEG胁迫导致菜豆黄化幼苗的叶绿素含量积累延迟,使叶片PSⅡ潜在最大光化学量子效率(F_v/F_m)、光适应下最大光化学效率(F_v′/F_m′)、PSⅡ光适应下实际光化学效率(Y(Ⅱ))和光化学荧光猝灭系数(qP)显著下降,而非光化学猝灭系数(NPQ)则显著增加。(2)在菜豆黄化幼苗转绿过程中,Pb或PEG胁迫导致其交替呼吸途径容量较对照均显著上升。(3)Pb或PEG胁迫下,交替呼吸途径抑制剂［水杨基氧肟酸(SHAM,1 mmol/L)］使菜豆黄化幼苗转绿过程中叶绿素含量、F_v/F_m、F_v′/F_m′、Y(Ⅱ)和qP进一步下降, NPQ却进一步增加,说明抑制交替呼吸途径会加剧Pb或PEG胁迫对PSⅡ反应中心活性的进一步抑制,使还原力积累加剧,造成热耗散进一步增加。研究表明,Pb或PEG胁迫均显著降低了菜豆黄化幼苗PSⅡ对光能的利用率,进而阻碍了菜豆黄化幼苗转绿进程;交替呼吸途径有助于在胁迫条件下缓解PSⅡ的过度还原,可能在一定程度上缓解了Pb或PEG胁迫对其转绿进程的阻碍作用。     

光胁迫下杂种杨无性系光合生理生态特征的研究

以气体交换测定结合合绿素荧光技术对几个杂种杨新无性系有自然光胁迫下的光合生理生态特性进行了分析。８月ＣＯ２气体交换测定显示,中午存在明显的光合作用下降现象,同时某些无性系午的气孔导度也有不同程度下降。叶绿素荧光分析显示,强光胁迫会影响光合作用的原初光反应过程,光系统Ⅱ（ＰＳⅡ）反应中心的最大光化学量子产率,有效光化学量子产率等反光系统Ⅱ反应中心活性的参数值在中午均比早晨低,与此同时,光系统Ⅱ反应中     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

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.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.