人工油松种群生长与生殖分配关系的研究

植物种群营养生长和生殖生长的关系是植物生殖生态学研究的重要内容之一,自本世纪70年代,国外已有大量报道,但国内的研究报道很少。本文在种群水平上研究了人工油松种群一年生雌性枝条和雄性枝条在枝长、直径、叶数、叶生物量、枝生物量及新生枝条在大小孢子球生物量、雌雄枝条长度和生物量等方面的差异,结果表明,一年生枝条除在西方向上雌雄枝条直径差异显著和在东、西方向上雌雄枝条生物量差异显著外,其它处理条件下雌雄枝条在长度、直径、叶数、叶生物量和枝生物量等方面差异均不显著;而对新生枝条的取样分析表明同方向上雌雄枝条在大小孢子球生物量、雌雄枝条长度、雌雄枝条生物量等方面差异均显著或极显著。无论是一年生枝条,还是新生枝条,在东、西、南、北四个方向上其各项指标差异显著或极显著。     

人工油松种群生长与生殖分配关系的研究

植物种群营养生长和生殖生长的关系是植物生殖生态学研究的重要内容之一,自本世纪７０年代,国外已有大量报道,但国内的研究报道很少。本在种群水平上研究了人工油松种群一年生雌性枝条和雄性枝条在枝长、直径、叶数、叶生物量、枝生物量及新生枝条在大小孢子球生物量、雌雄枝条长度和生物量等方面的差异,结果表明,一年生枝条除在西方向上雌雄枝条直径差异显和在东、西方向上雌雄枝条生物量差异显外,其它处理条件下雌雄枝     

葎草种群自疏过程中幼苗构件性状及生物量分配变化

以雌雄异株攀援草本植物葎草为材料,通过每10 d测量1次,连续6次,测定幼苗期葎草种群的密度和高度、个体构件性状和生物量分配等参数,分析种群自疏过程中种群密度与个体构件性状及生物量分配的关系,研究葎草种群的自疏规律。结果表明:幼苗期葎草种群存在显著的自疏现象,种群密度60 d内下降了71%;幼苗期葎草由直立生长向横向生长时,种群密度和株高显著降低;自疏过程中存留植株的茎性状有显著变化,变化大小为节间长主茎长茎直径,节间长增加,叶性状变化大小为叶面积叶柄长叶厚叶宽叶长总叶数保留叶片数,根性状变化大小为总根长根体积根数根长最大根长;自疏过程中存留植株的构件生物量、单株生物量显著增加,而单位面积累积生物量呈阶段性下降;留存植株的地上生物量分配比相对稳定(P0.05),根茎比和叶茎比有极显著变化(P0.01);叶、茎、叶柄生物量与根生物量和地上生物量之间均呈极显著的异速关系(P0.01),茎随地上生物量增长呈等速生长,而叶、叶柄和根随地上生物量增长呈异速生长,地上生物量与叶、茎、叶柄及根生物量极显著相关(P0.01);茎生物量与密度的异速关系遵循最终产量恒定法则,叶、叶柄和根生物量并不满足-3/2或-4/3或-1自疏法则;地上和单株总生物量与密度极显著相关(P0.01),存留单株的地上生物量和总生物量与密度的异速关系遵循最终产量恒定法则。     

在磷浓度不同的基质中种植密度对野菱生长的影响

研究了在3种不同磷浓度(低浓度27.56±0.78μg·g-1,中浓度52.85±1.30 μg·g-1,高浓度115.61±2.72μg·g-1)基质中,不同种植密度(11和32株·m-2)对野菱(Trapa incisa Sieb.et Zucc.)生长和不同部位磷含量的影响.结果表明,在磷浓度不同的基质中,野菱单株的根、茎和叶干质量及总干质量都随种植密度的提高而增加.种植密度的高低对野菱茎直径和叶数没有显著影响(P>0.05),但在3种基质中,种植密度高的野菱植株的叶数都高于种植密度低的野菱植株.种植密度埘野菱各部位干物质分配以及磷含量的影响因基质中磷浓度的不同而表现出不同的规律性;种植密度高的野菱植株的茎和叶片中的磷含量高于种植密度低的野菱植株,种植密度低的野菱植株的茎生物量比和根中的磷含量均高于种植密度高的野菱植株.研究结果显示,提高种植密度不仪能促进野菱个体的生长,且能促进磷在野菱体内的运输.     

底泥高磷浓度提高了喜旱莲子草的入侵性

植物通过改变自身的形态和生态生理特征对多变的环境因素做出响应,这种表型可塑性能增强外来物种的入侵能力。该文研究了入侵植物喜旱莲子草(Alternanthera philoxeroides)对底泥磷浓度、植株密度以及二者间交互作用的可塑性响应,探讨可塑性是否能使其获得更高的入侵能力。结果表明:低密度×底泥高磷浓度处理条件下的叶重、茎重、总重、叶数、分枝数和茎长等明显高于低、中磷浓度处理;高密度×底泥高磷浓度条件下的叶数、茎长和比茎长的值最大;植株的含磷量随底泥磷浓度的升高显著增加,说明喜旱莲子草响应底泥磷浓度变化时改变了自身的形态与生态生理性状。泥底含磷量对叶重比、叶数、茎长、茎磷含量、叶磷含量和植株总含磷量的影响都达到显著水平(p<0.05);植株密度对茎重、比茎长、叶磷含量和植株总磷含量的影响达到显著水平(p<0.05)。与入侵能力相关的叶重比、叶数、茎长在底泥高磷浓度处理中显著增加,说明底泥的高磷浓度增强了喜旱莲子草的入侵能力。     

广西亚热带主要林型的树干茎流

１９８０～１９９１年对广西亚热带主要林型的树干茎流进行定位观测,结果表明：广西亚热带主要林型的年树干茎流量为６．２～６６．７ｍｍ,分别占林外降雨量０．５～３．３％;不同林型的年树干茎流率显示阔叶林或针阔叶混交林（占１．７～３．３％）大于针叶林（占０．５～１．４％）。树干茎流的大小主要受树皮的吸水性能、树木胸径、树干枝角与冠型结构、降雨量及降雨强度的影响。杉木林树干茎流营养元素的年平均浓度为８．７０７～１４．８４８ｐｐｍ,是林外雨年平均浓度（２．４５３～３．７５３ｐｐｍ）的３．０～６．０倍;是林内穿透雨年平均浓度（５．８６１～１０．４５４ｐｐｍ）的１．４～２．０倍。说明树干茎流具有重要的水文生态功能。     

狗牙根营养繁殖体对模拟水淹的生物学响应

研究了水淹条件下狗牙根(Cynodon daetylon)繁殖体的形态特征和生物量的变化及其水淹后的恢复状况.结果表明,水淹深度的增加会诱导植株茎快速增高,而叶片数则明显下降.水淹时间对植株叶片数、茎直径、茎与根长比的影响显著,而对分枝数、茎长、根长、茎节数不显著.植株地上部生物量和总生物量随着水淹时间的延长而显著减少,但地下部生物量的变化不显著.所有实验处理的植株水淹后都能存活且恢复生长.但水淹对恢复期植株的生长仍有影响,植株的茎长、根长、分枝数、直径、叶片数、叶长、宽度以及叶的长宽比都随水淹时间的延长而显著减少,但茎节数与叶片数的差异不显著.根、茎、叶生物量和植株总生物量也随着水淹时间的延长而减少.实验表明狗牙根繁殖体通过延长茎长、改变叶形和减少生物量等方式对水淹显示出较强的耐受能力.     

温室茄子茎直径微变化与作物水分状况的关系

在温室条件下,采用盆栽土培和小区试验相结合的方法,以茄子(Solanummelongena,品种新乡糙青茄)为材料进行了植株茎直径微变化(膨胀或收缩)与作物体内水分状况的关系试验研究,旨在为利用茎直径微变化无损快速诊断作物水分状况提供理论依据。盆栽和小区试验均采用两因素(土壤水分梯度和作物不同生育阶段)随机区组设计,土壤水分控制下限分别取田间持水量的80%FC(Fieldwatercapacity),70%FC,60%FC和50%FC;生育阶段分别为苗期、花果期和采收期;共有4×3=12个处理组合,重复3次。结果表明:无论是在较高土壤含水量或在较低土壤含水量条件下,在晴好的天气里,茄子茎直径都是在白天收缩,傍晚、夜间复原或膨胀,而且这种微变化动态与植株体内的水分状况密切相关,不同土壤含水量条件下植株茎胀缩的幅度存在明显差异。高水分条件下,植株茎收缩幅度小,复原能力强;低水分条件下,植株茎收缩幅度大,恢复能力差。茎直径变化对环境因子水汽压差(VPD)的响应比较敏感,二者呈正相关关系,相关系数R2为0·8938。茎直径变化量(ΔSd)与叶水势(ψL)、叶片相对含水量(LRWC)呈极显著正相关关系,相关系数R2分别为0·867和0·965。这些结果显示,茎直径变化量能灵敏、实时、准确地反映植株体内的水分状况;与其它作物水分诊断方法(叶水势法,叶片相对含水量法,细胞液浓度法等)相比,茎直径微变化法可能具有简便、稳定、无损、连续监测和自动记录的优势。     

五叶爬山虎实生苗的生长特征对水分梯度下保水剂的反应

为探讨保水剂和未来降雨变化对五叶爬山虎实生苗生长特征的影响及寻求改善生态环境的途径,在内蒙古正蓝旗育草站开展了爬山虎实生苗生长特征对水分梯度下保水剂的反应的实验。结果表明:保水剂处理更能显著提高土壤的有效含水量,并能保持较长时间;爬山虎幼苗的株长、侧枝数、叶数及茎、叶、根和植株生物量增重等指标均随施水的增多而增大,但保水剂处理增幅较大,尤其是W3和W4两种供水与对照相比均达显著水平;保水剂处理还影响植株的生物量分配,尤其对叶重比和根重比影响显著,而茎重比和根冠比两种处理差异较小。     

亚低温与干旱胁迫对番茄植株水分传输和形态解剖结构的影响

为探讨亚低温和干旱对植株水分传输的影响机制,以番茄幼苗为试材,利用人工气候室设置常温(昼25 ℃/夜18 ℃)和亚低温(昼15 ℃/夜8 ℃)环境,采用盆栽进行正常灌水(75%～85%田间持水量)和干旱处理(55%～65%田间持水量),分析了温度和土壤水分对番茄植株水分传输、气孔和木质部导管形态解剖结构的影响。结果表明: 与常温正常灌水处理相比,干旱处理使番茄叶水势、蒸腾速率、气孔导度、水力导度、茎流速率、气孔长度和叶、茎、根导管直径显著减小,而使叶、茎、根导管细胞壁厚度和抗栓塞能力增强;亚低温处理下番茄叶水势、蒸腾速率、气孔导度、水力导度和叶、茎、根导管直径显著降低,但气孔变大,叶、根导管细胞壁厚度和叶、茎、根抗栓塞能力显著升高。亚低温条件下土壤水分状况对番茄叶水势、蒸腾速率、气孔导度、水力导度、气孔形态、叶、根导管结构均无显著影响。总之,干旱处理下番茄通过协同调控叶、茎、根结构使植株水分关系重新达到稳态;亚低温处理下番茄植株水分关系的调控主要通过改变叶和根导管结构实现,且受土壤水分状况的影响较小。     

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.