微囊藻毒素对沉水植物苦草生长发育的影响

MC RR抑制大型沉水植物苦草 (Vallisnerianatans (Lour.)Hara .)的生长和发育。在 0 0 0 0 1— 10mg/L的浓度下 ,苦草种子的发芽、子叶生长、真叶的形成和生长、不定根的形成和生长以及根毛的生长都受到了一定的抑制作用。当MC RR浓度≥ 0 .1mg/L时 ,处理第 30d ,MC RR对苦草鲜重和第一片真叶的生长有极显著的抑制作用 ,当MC RR浓度为 10mg/L时 ,根的生长和叶片的发生也受到了极显著的抑制作用     

不同基质对四种沉水植物生长的影响

通过模拟试验,研究了太湖五里湖主要3种基质类型(沙石、生土、湖泥)对4种沉水植物(苦草、马来眼子菜、金鱼藻、轮叶黑藻)生长的影响. 结果表明,生长于沙石、生土、湖泥上的苦草和马来眼子菜平均生物量分别为72.37、126.25、134.10 g和40.0、72.10、90.70 g,而金鱼藻和轮叶黑藻平均生物量分别为0.27、6.58、73.64 g和0.17、3.26、84.42 g,说明湖泥较适合这四种沉水植物生长. 苦草和马来眼子菜对相对贫瘠的生土有较强的适应性,而金鱼藻和轮叶黑藻不适宜在生土中生长. 生长在沙石上的4种沉水植物的生物量和株高最低,其中金鱼藻和轮叶黑藻于试验期间死亡.苦草的根系活力(TTC)低于马来眼子菜,生长在沙石、生土、湖泥中苦草的根系活力分别为0、(0.16±0.05) mg·g^-1·h^-1和(0.36±0.33) mg·g^-1·h^-1,而马来眼子菜则分别为(2.68±0.34) mg·g^-1·h^-1、(2.30±0.77) mg·g^-1·h^-1、(5.24±0.67) mg·g^-1·h^-1. 叶绿素、质膜透性和丙二醛(MDA)的测定结果进一步证明了以上结论.此外,苦草、马来眼子菜和轮叶黑藻对基质有较强的沁氧能力,其大小顺序为苦草＞马来眼子菜＞轮叶黑藻.     

大叶补血草LgNHX1基因对烟草的遗传转化及耐盐性分析

目的:通过农杆菌介导法将大叶补血草液泡膜Na+/H-逆向转运蛋白基因LgNHX1转化烟草,并对转化烟草的耐盐性进行分析.方法:采用叶盘法进行遗传转化,对得到的转化植株经PCR和RT-PCR鉴定后,用不同浓度的NaCl溶液胁迫,分别测定了它们的丙二醛含量、相对电导率及根和叶中的K+和Na+含量.结果:在200～300mmol/L NaCl胁迫下,转基因植株叶片的丙二醛含量分别为2.85nmol/g FW、3.50nmol/g FW,对照为3.25nmol/g FW、4.39nmol/g FW;转基因植株叶片的相对电导率分别为42.22%、74.10%,对照为53.2%、84.33%;在300mmol/L NaCl胁迫下,转基因植株根和叶中的K+/Na+比分别为5.80和3.10,对照为4.32和2.35.结论:在NaCl胁迫下,转基因烟草的耐盐性有了一定程度的提高.     

假臭草对菜青虫杀虫活性的研究

测定了假臭草根、茎、叶的甲醇提取液对菜青虫的生物活性。结果表明假臭草根、茎、叶的甲醇提取液对菜青虫无触杀活性;假臭草提取液对菜青虫的拒食活性强弱依次为叶茎根,在浓度为1 g/mL时拒食率分别为36.51%、63.34%和79.33%;假臭草茎和叶的甲醇提取液对菜青虫有一定的胃毒作用,在浓度为1 g/mL时,假臭草叶和茎甲醇提取液对菜青虫的胃毒活性分别为66.67%和33.33%。     

矮壮素对苦草矮化特征及生理指标的影响

沉水植物生长过高引起水体污染问题受到人们高度重视。本文在实验室模拟条件下,研究了0(CK)、0.01、0.02、0.10、0.20、0.50、0.75、1.00和1.25g.L-1共9个不同浓度矮壮素对苦草(Vallisnerianatans)矮化特征及生理指标的影响。结果表明:不同浓度处理30d后苦草株高具有显著差异性(P<0.05),且浓度越高矮化效果越显著;矮壮素使苦草叶宽增加、根长缩短,其中浓度在0.02～0.20g.L-1时苦草根冠比增加,浓度在0.01～0.50g.L-1时苦草株数增加明显;矮壮素浓度在0.10～0.50g.L-1时,苦草湿重增加61%～123%,将从水中或底泥中吸收更多N、P等营养物质,增强其净化水质的能力;当矮壮素浓度为0.02g.L-1时,不仅苦草矮化的效果较好,占据空间相对较小,而且苦草根长生长较长,根冠比较大,叶绿素含量增加,SOD、POD酶活性升高,苦草抗逆性增强,延缓植株衰老。因此,0.02g.L-1浓度矮壮素对苦草矮化较为适宜。     

淡水小球藻分离培养及其对水体辛硫磷的降解功能研究

为了研究微藻对水体有机磷农药的降解和积累效果,从自然水体中富集纯化得到一株蛋白核小球藻(Chlorella pyrenoidosa),以该藻细胞为研究对象,以水产养殖中常用的有机磷杀虫剂辛硫磷为实验药物,通过高效液相色谱法研究了蛋白核小球藻对辛硫磷的富集和降解效果。结果显示,富集纯化藻细胞通过显微镜检与分子生物学检测鉴定为蛋白核小球藻,命名为MH-1。急毒性试验表明,辛硫磷浓度在高于2.0 μg/mL时才会对MH-1生长产生显著抑制作用,表现在叶绿素含量与生物量显著下降。在2.0 μg/mL及以下浓度辛硫磷存在的水体中,MH-1具有降解辛硫磷的功能,在0.2 μg/mL和2.0 μg/mL浓度组中,5 d内的辛硫磷净降解率分别为49.66%和39.61%,日平均降解速率分别为0.02 μg/mL和0.38 μg/mL。MH-1对辛硫磷也有一定的富集能力,72 h内MH-1对辛硫磷的富集呈现先升高后降低的趋势,120 h时MH-1对0.2 μg/mL和2.0 μg/mL的辛硫磷富集量分别为0.16 mg/g FW(Fresh weight,FW)和0.25 mg/g FW。结果表明,MH-1对辛硫磷具有良好的吸附效果。     

高浓度CO2下苦草的生长和生理生化反应

对沉水植物苦草 (VallisneriaspiraslisL .)在高浓度CO2 (10 0 0 μmol/mol)和对照浓度CO2 (35 0 μmol/mol)下的生长特征和生理生化指标进行了比较研究。在实验的早期阶段 ,从冬芽出苗的苦草幼株在高浓度CO2 下生长明显加快 ,但由于后期生长逐渐放慢 ,其最终总生物量比对照组仅高出 11.6 %。尽管高浓度CO2 也促进了根的生物量的累积 ,但是由于苦草叶片生物量占总株生物量比例大 ,高浓度CO2 下苦草生物量的增加主要反映为叶片生物量的增加。在实验后期阶段 ,高浓度CO2 促进了苦草冬芽的形成。实验过程中 ,苦草的根叶生物量比 (RLR)在高浓度和对照浓度CO2 下均有所降低 ,二者之间无明显统计学差异。高浓度CO2 下苦草叶片中叶绿素含量和可溶性蛋白质含量降低 ,而可溶性总糖含量明显增加。     

高产SOD大蒜悬浮细胞系的选育

筛选获得了高产 SOD大蒜悬浮细胞系 ,培养 1 8d后达到最大生物量及最大 SOD总酶活分别为2 2 .1 2 g.DW/ L及 1 0 .81× 1 0 4 U/ L,最大单位细胞酶活为 679.67U/ g.FW,SOD最大比活力可达 85 .98U/mg Pro,具有较强的 SOD合成能力。     

镉在土壤-香根草系统中的迁移及转化特征

以无植物组处理为对照,采用盆栽试验方式探讨不同Cd浓度胁迫条件下香根草根际土壤中重金属Cd的积累、迁移及转化特征。土壤Cd处理设4个浓度梯度,分别为0、2、20、80 mg/kg土壤干重。结果表明:(1)香根草可以显著降低土壤中生物有效态Cd和总Cd含量。(2)香根草各部分Cd积累量随处理浓度的增加和处理时间的延长而增加,90 d时80 mg/kg处理组地上部分和根的Cd积累量分别高达180.42 mg/kg和241.54 mg/kg。(3)各浓度Cd处理下,富集系数随着Cd处理浓度的增加而显著降低,随处理时间的延长而升高。(4)香根草地上部分Cd含量小于根部,各处理转移系数均小于1。随着处理时间的延长,中低浓度处理组的转移系数稍有降低,高浓度处理组的转移系数则显著上升。(5)种植香根草使其根际土中残渣态的Cd转化为生物有效态Cd,提高Cd清除效率。研究结果表明,香根草能够有效地吸收土壤中的Cd,降低土壤中总Cd含量,提高土壤安全性,可作为Cd污染地区植物修复的备选物种。     

群落演替对呼伦贝尔草地两种优势植物繁殖分配及生态化学计量的影响

为了探究草地群落演替过程中不同优势种的生理生态适应性,本研究采用空间代替时间序列的方法,分析呼伦贝尔草地米氏冰草群落—米氏冰草+冰草群落—冰草群落演替系列的土壤养分、两优势种的生物量及C、N和P含量。结果表明: 随着米氏冰草群落—米氏冰草+冰草群落—冰草群落的演替,土壤全碳、全氮、速效氮及速效磷含量均显著升高;米氏冰草和冰草叶、茎和根的N、P含量及N/P均显著升高,而各构件的C/N降低;米氏冰草叶的C含量及冰草叶、茎和根的C含量均显著升高。米氏冰草叶C/P及冰草根和叶C/P均显著升高,而米氏冰草根和茎C/P及冰草茎C/P均显著下降。在米氏冰草+冰草共优势种群落中,米氏冰草通过降低茎和根C含量,增加叶C的积累,提高其种间竞争力, 而冰草通过降低根冠比和生殖比来适应环境变化。米氏冰草在不同群落中均受N限制(N/P<14);而冰草在单优势种群落中受P限制(N/P>16),在共优势种群落中受N和P限制(14相似文献   

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.