蛋白质修饰剂、变性剂和活性氧对菠菜叶片光系统Ⅱ光失活的影响

菠菜叶圆片以活性氧、蛋白质修饰剂和变性剂结合强光处理半小时,检测叶绿素荧光动力学并与单照强光的对照作比较。加人H2O2、·O2、OH·和O2等活性氧加剧了PSⅡ的光抑制作用,Fv／Fm,qp和PSⅡ降低,qn和1—qp相应上升。4种蛋白质修饰剂NBS、DEPC、BDE和pCMB的处理,使叶片的Ch1荧光参数发生了与活性氧作用相类似的变化,尤以精氨酸残基修饰剂BDE的影响较为显著。SDS明显地影响FV和qp但未改变qN值。Gu－HC1导致qp完全丧失,qN达最大值。低浓度的脲素和DMSO略为降低PSⅡ活性和增大qN。结果认为对叶绿体蛋白构象或结构的任何改变皆引起光下PSⅡ光失活作用的增强。     

夜间低温后日间光照对海桐和榕树叶片的光抑制以及光系统Ⅱ功能的影响

夜间低温导致海桐和榕树叶片光系统Ⅱ(PSⅡ)最大光化学效率(Fv/Fm)、PSⅡ光合电子传递量子效率(φPSⅡ)、天线转化效率(F'v'/Fm')、非光化学猝灭系数(NPQ)降低,其后日间光照先引起海桐叶片Fv//Fm、ΦPSⅡ、F'v'/Fm'稍微降低,其后又逐渐得到恢复,但NPQ却表现出相反趋势;夜间低温及随后的日间光照并未对海桐叶片光化学猝灭系数(qP)和初始荧光强度(Fo)产生影响.夜间低温后日间光照进一步引起榕树叶片Fv/Fm、ΦPSⅡ、Fv'/F'm、qp、NPQ下降,在午后光照减弱后仍不能得到恢复.     

草丁膦对转bar基因水稻GS酶活性和光合功能的影响

喷施草丁膦后,对草丁膦无抗性水稻Cypress(未转bar基因)叶片的谷氨酰胺合成酶(GS)活性先受到抑制,随后叶片内NH 4积累上升,叶绿素含量、PSⅡ原初光化学效率(Fv/Fm)、光能转化效率(ΦPSⅡ)和叶片叶绿素荧光的光化学猝灭系数(qp)下降,光合速率显著降低;最后引起植株死亡.另一方面,Cypress PB-6(转bar基因抗草丁膦水稻)的GS酶活性在喷施草丁膦后虽然先被抑制,但随后能恢复至正常水平,接着NH 4积累下降,草丁膦对叶绿素含量、荧光参数Fv/Fm、ΦPSⅡ、qp的影响被解除,光合速率恢复到正常水平,整个植株生长正常.     

S3307对柚树苗叶片光合特性的影响(简报)

S3307能提高沙田柚和琯溪蜜柚幼苗的叶绿素和类胡萝卜素含量,降低Chla／b值。经50～200mg·L-1S3307处理的柚树幼苗光合速率、荧光参数Fv／Fo、Fv／Fm、φPSⅡ、qP值上升,Rd／Pn、qN、KD值下降。     

强光下SO_3~(2-)和HCO_3~-对盐藻叶绿素荧光的影响

强光下（1000μmolm-2s-1）用低浓度（1mmol／L）处理盐藻1h,其Fv／Fm、qN,qp和PSⅡ都较暗对照高。随着SO浓度（5,25,50,100mmol／L）的提高,Fv／Fm、qN、qp和ΦPSⅡ下降。20mmol／L的HCO3-可减缓这种下降趋势。强光下1mmol／LHCO3-对25mmol／LSO产生的光抑制不但没在减弱反而有所加强,提高HCO3-浓度则有减弱作用,尤以50mmol／L的效果最好,而且qN可随HCO3-浓度的增高而上升,至100mmol／L才略有下降。低浓度下SO（5mmol／L）强光的光抑制在随后的低光条件下（40μmolm-2s-1）放置2h能完全恢复,高于此浓度引起的光抑制不能完全逆转。低光下HCO3-能促进光抑制的恢复。     

不同浓度Ni、Cu处理对骆驼蓬光合作用和叶绿素荧光特性的影响水

以骆驼蓬幼苗为材料,采用盆栽试验研究不同浓度(0、50、100、200、400 mg·kg-1)Ni、Cu处理对骆驼蓬叶片光合作用、叶绿素荧光特性及生长状况的影响.结果表明:随着Ni浓度的增加,骆驼蓬幼苗叶片的光合色素含量、净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)、PS Ⅱ最大光化学效率(Fv/Fm)、PS Ⅱ电子传递量子产率(φpsⅡ)、光化学猝灭系数(qp)及各项生长指标均呈显著下降趋势,而细胞间隙CO2浓度(Ci)和非光化学猝灭系数(qn)呈显著增加趋势,其中Pn的下降主要是由非气孔限制所致;骆驼蓬幼苗叶片的光合色素含量、Pn、Gs、Tr、Ci、Fv/Fm、φpsⅡ、qp及各项生长指标均在50 mg·kg-1Cu处理时达到峰值,叶绿素a和b、Pn、Gs、Tr、Ci、Fv/Fm及各项生长指标值在100 mg·kg-1Cu处理时仍微高于对照,而后随Cu浓度的增加,光合色素含量、Pn、Gs、Tr、Ci、Fv/Fm、φpsⅡ、qp及各项生长指标均呈下降趋势,qN呈增加趋势,其中Pn的下降主要是由气孔限制所致.     

强光及外源活性氧对莴苣叶绿素荧光的影响

莴苣叶绿体在强光处理下发生光抑制,主要表现为叶绿素荧光参数Ｆｖ／Ｆｍ和ΦＰＳⅡ降低;外源活性氧Ｈ３Ｏ２,Ｏ＾－２,ＯＨ和＾１Ｏ２均能引起叶绿体ＰＳⅡ光化学效率Ｆｖ／Ｆｍ不同程度的下降,其中以＾１Ｏ２影响最明显：Ｈ２Ｏ２在诱导叶绿体荧光猝灭过程中,引起荧光产量降低,而使ｑｐ,ｑＮ,ΦＰＳⅡ,ＫＤ上升;     

重金属对盐生草光合生理生长特性的影响

以盐生草幼苗为试验材料,分别设置0(CK)、50、100、200、400μg?g-1的Ni2+、Cu2+处理,研究重金属Ni2+和Cu2+对盐生草光合生理特性的影响.结果表明:盐生草叶片光合色素含量、净光合速率(Pn)、气孔导度Gs、蒸腾速率Tr、PSⅡ最大光化学效率Fv/Fm、非光化学猝灭系数qN及生长指标(株高、地上部干重和鲜重)在50μg?g-1的Ni2+处理时均达到最大值,后随Ni2+浓度继续增加,其叶片叶绿素a、叶绿素b、Pn、Gs、Tr、Fv/Fm、PSⅡ电子传递量子产率ΦPSⅡ、光化学猝灭系数qP、qN及各项生长指标逐步下降并低于对照水平,而细胞间隙CO2浓度(Ci)较对照呈增加趋势.在50μg?g-1的Cu2+处理时,盐生草叶片光合色素含量、Pn、Gs、Tr、Ci、Fv/Fm、ΦPSⅡ、qP、qN及各项生长指标均达峰值;在100μg?g-1Cu2+处理时,光合色素含量、Pn、Gs、Tr、Fv/Fm、ΦPSⅡ、qN及各项生长指标较对照仍有增加,而后随Cu2+浓度继续增加,其叶绿素a、叶绿素b、各光合参数、叶绿素荧光参数及生长指标均逐步降低并低于对照.可见,盐生草Pn在Ni2+胁迫下的下降主要是由非气孔限制所致,而Cu2+胁迫下的下降主要是由气孔限制所致;低浓度Ni2+和Cu2+对盐生草生长具有一定促进作用,过高浓度Ni2+和Cu2+则会通过抑制盐生草叶片叶绿素合成,影响其光合作用,从而抑制植株生长.     

草莓叶绿素荧光参数日变化的研究

以草莓（Fragaria ananassa Duch）为材料,研究其叶片叶绿素荧光参数的日变化。在自然光下,草莓叶片的最大荧光（Fm）、PSⅡ光化学效率（Fv／Fm）、PSⅡ光量子效率（Yield）和光化学猝灭系数（qP）从6：00-18：00均先下降后上升,其中在下午14：00最低;而非光化学猝灭系数（qN）先上升后下降,其中在下午14：00最高。表明在中午强光下,草莓叶片遭受了强烈的光抑制,而热耗散是其主要的光保护机制。     

短期UV-B辐射对青藏高原美丽风毛菊PS Ⅱ光化学效率的影响

通过短期增补UV-B辐射模拟试验,研究了青藏高原典型天气(晴天、多云、阴天)下高山植物美丽风毛菊叶片的叶绿素荧光参数变化.结果表明:随天气由晴变阴,美丽风毛菊叶片暗适应3 min的PSⅡ最大光化学量子效率(Fv/Fm)显著升高,实际PSⅡ光化学效率(ФPSⅡ)和光化学猝灭系数(qp)也升高,而非光化学猝灭系数(NPQ)则降低,可见光辐射(PAR)是影响PSⅡ光能转化效率的主要因素.增补UV-B辐射后,3种典型天气下,美丽风毛菊叶片的Fv/Fm和NPQ略有降低,ФPSⅡ和qp略微增加,但对光合气体交换过程没有产生负影响.叶片净光合速率Pn和ФPSⅡ的增高趋势与增补UV-B辐射下相对较多的UV-A成分有关,同时也得益于叶片厚度的增加.UV-B辐射对叶片光合机构具有潜在负影响.     

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.     

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     

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.     

鸡传染性法氏囊病病毒研究进展

传染性法氏囊病(Infection bursal disease, IBD)是由鸡传染性法氏囊病毒(Infectious bursal disease virus, IBDV)引起的鸡和火鸡的一种高度接触性传染病,给世界各国的禽养殖业带来了巨大损失.自IBDV发现至今新的变异株不断出现,分子结构的改变导致病毒致病力的改变及宿主对疫苗应答的改变,使得传统的疫苗已不能控制其流行,因此各国学者对其基因组结构和功能进行了广泛深入的研究,并积极研制新型有效的疫苗以达到防治的目的.     

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.     

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).