铅胁迫对3种藓类植物抗氧化酶活性的影响

采用水培实验研究了重金属Pb对3种藓类植物尖叶拟船叶藓(Dolichomitriopsis diversiformis)、湿地匍灯藓(Plagiomnium acutum)和匍枝青藓(Brachythecium procumbens)的抗氧化酶(SOD、POD和CAT)活性的影响.结果表明,(1)在1~200 mg·L-1的铅胁迫浓度范围内,Pb对3种藓类植物的SOD活性均具有显著的促进作用,对Pb胁迫的种间敏感性差异为尖叶拟船叶藓>湿地匍灯藓>匍枝青藓;(2)POD活性对Pb胁迫的反应趋势有一定差别,尖叶拟船叶藓和匍枝青藓的POD活性随Pb浓度的增加先升后降,湿地匍灯藓的POD活性变化较为平缓,种间敏感性差异为匍枝青藓>尖叶拟船叶藓>湿地匍灯藓;(3)在100 mg·L-1时Pb对湿地匍灯藓CAT活性表现为显著促进作用外,其余在低浓度下显示无显著影响,在高浓度下表现为抑制效应,种间敏感性差异为尖叶拟船叶藓>匍枝青藓>湿地匍灯藓.3种藓类植物的抗氧化酶体系中对Pb胁迫的抵抗起关键作用的是SOD,可作为藓类植物受Pb胁迫的敏感生理指标.3种植物中对Pb胁迫的反应较为敏感的是尖叶拟船叶藓.     

镉胁迫下三种藓类植物的细胞伤害及光合色素含量的变化

采用水培试验研究了不同浓度Cd 胁迫下3种藓类植物的细胞伤害、光合色素含量和Cd 含量的变化,以探讨其对Cd 胁迫的反应敏感性和耐性.结果表明：低浓度Cd （1 mg·L^-1）胁迫显著损伤尖叶拟船叶藓和匍枝青藓叶细胞,3种藓的叶细胞伤害率随Cd 浓度的升高而显著增加,高浓度Cd （100 mg·L^-1）胁迫下的细胞伤害率大小为匍枝青藓>湿地匍灯藓>尖叶拟船叶藓.低浓度Cd 胁迫（1 mg·L^-1）对3种藓类植物的总叶绿素含量无显著影响,随着Cd 胁迫浓度的增加（≥ 10 mg·L^-1）,3种藓类植物总叶绿素含量显著下降,降幅顺序为匍枝青藓>湿地匍灯藓>尖叶拟船叶藓;1和10 mg·L^-1 Cd胁迫对3种藓类植物叶绿素a/b值无显著影响,100 mg·L^-1 Cd胁迫下湿地匍灯藓和匍枝青藓叶绿素a/b值显著下降;Cd胁迫对匍枝青藓类胡萝卜素含量的影响最大,1 mg·L^-1 Cd下其类胡萝卜素含量显著降低.3种藓类植物均能显著地富集Cd,其体内Cd累积量以尖叶拟船叶藓最高,湿地匍灯藓次之,匍枝青藓最少.细胞伤害率、叶绿素和类胡萝卜素含量的变化可用来指示3种藓类植物对Cd胁迫的敏感性差异.尖叶拟船叶藓对Cd胁迫的耐受性最强,湿地葡灯藓和匍枝青藓相对较弱.3种藓类植物对Cd胁迫的耐受性与其体内Cd累积量呈明显的正相关关系.     

铅胁迫对3种藓类植物细胞伤害及光合色素含量的影响

采用水培实验研究了重金属Pb2+胁迫下3种藓类植物[尖叶拟船叶藓(Dolichomitriopsis diversiformis)、湿地匍灯藓(Plagiomnium acutum)和匍枝青藓(Brachythecium procumbens)]的细胞伤害、光合色素含量和Pb2+累积量的变化,以探讨藓类植物对Pb2+胁迫的反应敏感性和耐性强弱.结果表明:(1)Pb2+胁迫导致尖叶拟船叶藓、湿地葡灯藓和匍枝青藓叶细胞显著损伤的最低浓度分别为100、1和10 mg·L-1,叶细胞伤害随Pb2+浓度的升高而显著增加,它们对高浓度Pb2+的耐受性顺序为尖叶拟船叶藓>湿地匍灯藓>匍枝青藓;(2)低浓度Pb2+胁迫(小于100 mg·L-1)对3种藓类植物的总叶绿素含量均没有影响,高浓度Pb2+胁迫则导致总叶绿素含量显著下降,降幅依次为匍枝青藓>湿地匍灯藓>尖叶拟船叶藓;叶绿素a/b值显示,高浓度Pb2+胁迫对尖叶拟船叶藓叶绿素b的抑制远大于叶绿素a,而对匍枝青藓和湿地葡灯藓使叶绿素a的抑制大于叶绿素b;当Pb2+胁迫浓度达到200 mg·L-1时3种藓类植物的类胡萝卜素含量显著降低;(3)3种藓类植物均能显著地富集Pb2+,高浓度Pb2+胁迫下,其富集能力急剧增加,而且与其耐受性呈正相关.     

尖叶拟船叶藓光系统Ⅱ光合荧光特性、活性氧代谢与耐脱水生理生态适应的关系

以广布湿生藓类——湿地匐灯藓(Plagiomnium acutum)为比较材料,研究东亚特有濒危植物尖叶拟船叶藓(Dolichomitriopsis diversiformis)在不同快速脱水和复水胁迫下PSⅡ的叶绿素光合荧光变化和活性氧代谢及抗氧化系统变化,探讨两种藓类生理生态适应性差异的成因,以初步确定尖叶拟船叶藓受水分条件限制分布狭窄趋于濒危的原因。结果显示:(1)尖叶拟船叶藓的光合电子传递在脱水后可被极微弱光完全抑制,其抑制光强的恢复明显慢于湿地匐灯藓;其PSⅡ最大光化学效率(Fv/Fm)和实际光化学量子效率(YⅡ)先降而后升,恢复较慢;光化学淬灭(q P)复水后恢复较快,非光化学淬灭(NPQ)的绝对值和变化速率则始终低于湿地匐灯藓。(2)尖叶拟船叶藓活性氧水平明显高于湿地匐灯藓;其SOD、CAT、APX等抗氧化系统酶活性整体变化幅度较大,抗氧化保护物质(As A)含量则明显低于湿地匐灯藓。以上结果表明尖叶拟船叶藓受到环境水分因子限制的原因主要有:(1)PSⅡ的反应中心色素(P680)对脱水伤害较为敏感;(2)复水修复过程中抗氧化保护系统的保护能力偏低。     

长白山森林生态系统腐木生苔藓植物生态分布的DCA排序研究

应用除趋势对应分析（ＤＣＡ）对长白山不同森林类型腐木生苔藓植物分布研究表明,长白山红松阔叶混交林、暗针叶林以及两者之间的过渡林林下腐木生苔藓植物组成明显不同．红松阔叶混交林以尖叶匍灯藓、毛尖羽藓、细枝青藓等为主;过渡林以尖叶匍灯藓、鞭枝疣灯藓、羽藓、腐木藓、塔藓等为主;暗针叶林的以塔藓、钩枝镰刀藓、拟垂枝藓、曲背藓、毛梳藓等为主．暗针叶林林下腐木生苔藓植物发生量最大,物种的多样性也最高．海拔高度和林冠郁闭度是影响长白山森林林下腐木生苔藓植物生态分布的主要因素．     

高温胁迫下两种藓类植物过氧化物酶活性的变化

在不同的高温胁迫条件下 ,对湿地匍灯藓 (Plagiomnium acutum)和大羽藓 (Thuidium cymbifolium)过氧化物酶 (POD)活性及其与处理时间和处理温度的关系进行了初步研究。结果表明 ,在一定的温度范围内 ,随着温度的升高 ,POD活性增加 ,二者成线形关系。在一定温度条件下 ,一般随着处理时间的延长 ,POD活性增加。但是当超过一定的温度 (4 5～ 5 0°C)以及一定的处理时间 (4～ 6h) ,POD活性有所下降。结果还表明 ,湿地匍灯藓的POD活性显著高于大羽藓。而且在高温胁迫下 ,湿地匍灯藓 POD活性变化比大羽藓活跃 ,其变化幅度也比大羽藓大。     

湖南藓类植物新资料

报道了湖南藓类7个新分布种:虾藓东亚亚种(Bryoxiphium norvegicum ssp. japonicum,隶属于虾藓科Bryoxiphiaceae,为湖南新记录科)、细拟合睫藓(Pseudosymblepharis duriuscula)、大叶真藓(Bryum pseudotriquetrum)、密叶匍灯藓(Plagiom niumconfertidens)、尖叶匍灯藓(P.cuspidatum)、石地青藓(Brachythecium glareosum)和毛叶梳藓(Ctenidium capillifolium,梳藓属为湖南新记录属)。并对它们的生境和地理分布进行了初步讨论。     

秦岭十四种藓类植物的染色体观察

本文以藓类植物的幼嫩孢蒴为材料,对秦岭地区14种藓类植物的染色体作了观察,并对其中的长尖提灯藓进行了核型分析。结果如下：细叶真藓Bryum capillare L.ex Hedw．n＝10;长尖提灯藓Mnium lycopodioides Schwaegr．n＝6,核型公式为n＝6＝3m+3sm(1SAT)侧枝匍灯藓Plagiomnium maximoviczii(Lindb．)T．Kop．n＝6;梨蒴珠藓皱叶变种Bartramia pomiformis var．elongata Turn. n=10+2m;细枝羽藓Thuidium delicatulum (Hedw.) Mitt. n=11;尖叶羽藓Thuidium philibortii Limpr. n=10+1m;褐黄水灰藓Hygrohypnum ochraceum (Wils.) Loesk. n=10;钩枝镰刀藓Drepanocladus uncinatus (Hedw.) Warnst. n=7+3m; 黄叶细湿藓Campylium chrysophyllum (Brid.) J. Lange. n=10;林地青藓Brachythecium starkei (Brid.) B. S. G. n=16;多褶青藓 Brachythecium buchananii (Hook.) Jaeg. n=6;扁枝小锦藓Brotherella yokohamae (Broth.) Broth. n=9+2m; 粗枝藓Gollania neckerella (C. Mull.) Broth. n=7; 暖地金发藓, Pogonatum fastigiatum Mitt. n=7;其中粗枝藓和扁枝小锦藓的染色体数尚未见报道;林地青藓和多褶青藓的染色体数与所见报道的结果不同：其余10种与前人报道的结果一致。     

快速脱水与复水过程中2种藓类植物的活性氧代谢与脂质过氧化特征

以来自不同水分生境的金发藓和湿地匐灯藓为材料,对二者在脱水与复水胁迫条件下的活性氧代谢、脂质过氧化损伤程度及其抗氧化系统应答的差异进行比较研究。结果显示:在脱水与复水过程中,(1)硅胶快速脱水更接近阳光直射条件下藓类植物的水分丧失。(2)随着含水量的变化,湿地匐灯藓虽然能够在复水后迅速修复细胞的完整性,但变化剧烈;金发藓则能够始终维持较低的膜透性。(3)2种藓类植物的丙二醛(MDA)含量变化均呈先升后降趋势,但金发藓的MDA含量明显低于湿地匐灯藓。(4)2种藓类植物的超氧阴离子自由基(O2.-)产生速率和过氧化氢含量(H2O2)的变化均与MDA含量变化相似,且金发藓活性氧水平明显高于湿地匐灯藓。(5)2种藓类植物的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性受活性氧诱导亦呈先升后降的趋势,但金发藓抗氧化酶对活性氧迸发的应答更快,活性更强。(6)2种藓类植物的抗坏血酸(AsA)含量呈先降后升态势,但金发藓的含量低于湿地匐灯藓。研究表明,来自不同生境的2种藓类植物对脱水胁迫所致的氧化胁迫均具有很强的适应能力,尤其是复水过程中的修复能力,但不同藓类可能通过不同途径和机制来适应脱水所致的氧化胁迫;来自易发生水分亏缺生境的金发藓可能因具有更强抗氧化能力,从而获得比来自水分充沛生境的湿地匐灯藓更高的脱水耐性。     

两种匍灯藓属植物夏季和冬季光合特性的比较研究

分别对生长于冬季和夏季的五倍子蚜虫冬寄主藓类植物湿地匍灯藓(Plagiomnium acutum(Lindb.)T.Kop.)和侧枝葡灯藓(Plagiomnium maximoviczii(Lindb.)T.Kop.)的净光合速率及其与光照、温度的关系进了比较研究.结果表明,2种藓类的最大光合能力在夏季分别为125.67和94.63μmolCO2     

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).