初析赤潮成因研究的围隔实验结果Ⅱ.浮游植物群落演替与甲藻赤潮

探讨了甲藻赤潮与浮游植物演替的关系．多次国隔生态系实验结果表明,在水体相对稳定的生态系中,富营养后总是先发生硅藻的水华或赤潮．随后浮游植物会演替成占优势的甲藻,甚至形成甲藻赤潮．维生素Ｂ（１２）的异常增多可能加速这种演替的进程．但这种稳定水体若受到扰动,将干扰演替,使硅藻水华持续不断地发展,阻碍甲藻形成优势．这可以防止甲藻赤潮的生成．     

海洋围隔生态系中赤潮发生前后浮游植物群落结构的初步分析

1990年5至7月,在国家海洋局第三海洋研究所陆基水池中进行了了围隔生态系内富营养化引起的生态效应实验。实验表明,富营养的围隔袋中,浮游植物群落结构逐渐发生了变化,组成和数量都有很大的变动。形成水华和赤潮。并发生了种群的演替。水华以硅藻开始,形成高潮之后便衰退。随后微鞭毛藻和甲藻开始较大量繁殖。金藻和甲藻在实验中形成赤潮,最高值达到6.7×10~(10)cells/m~3。甲藻和硅藻的生长似乎互相抑制。实验初期,在硅藻繁盛时,甲藻的种、属和数量都很少。而在演替的后期,硅藻衰落时,甲藻占优势。数量最高达2.6×10~8cells/m~3。实验演示了发生在硅藻水华之后的甲藻赤潮发展过程,与1986年厦门西海域发生的裸甲藻赤潮的发展过程相似。实验结果为进一步研究甲藻赤潮的形成规律及其预测预报积累了资料和经验。     

不同营养盐条件下赤潮高发区围隔生态系内多胺的变化

在东海赤潮爆发区域运用围隔生态系实验方法,研究了不同营养盐条件下围隔生态系内多胺浓度变化。结果表明:2010年选用东海原甲藻赤潮爆发处海水,东海原甲藻是各围隔生态系内主要优势种,没有种群演替现象发生。两种营养盐添加方式下各围隔内精胺浓度维持较高水平,都呈现先波折下降后波折上升的趋势,与东海原甲藻的生长变化正好相反;各围隔内腐胺浓度水平较高,变化起伏较大,其中有两个实验组腐胺整体变化趋势与东海原甲藻生长趋势类似;所有围隔内亚精胺浓度最低,波动较小。2011年取用中肋骨条藻赤潮爆发处海水,所有围隔生态系内优势种都发生了从中肋骨条藻到东海原甲藻的演替。各围隔生态系内腐胺浓度最高,在中肋骨条藻生长初期腐胺浓度下降,随着中肋骨条藻的生长有所上升,实验后期随着东海原甲藻的生长又整体呈现出下降趋势;各实验组精胺浓度较低,在中肋骨条藻消亡东海原甲藻出现的种群演替期间,都呈现出较大波动;各围隔内亚精胺浓度较低,在整个种群演替过程中没有明显的变化。围隔生态系中补充营养盐,通过对浮游植物生长的影响,间接影响围隔生态系内的多胺变化。     

东海两种赤潮生物种间竞争的围隔实验

1998年5月和2002年5月在东海赤潮高发区进行了两次添加营养盐诱发赤潮的围隔实验,结果表明,1998年5月实验开始时,具齿原甲藻和中肋骨条藻分别占群落总量的85％和11％,对照围隔中,具齿原甲藻一直处于优势,高峰时所占比例接近99％．加磷围隔中,中肋骨条藻显示出很强的竞争能力,第五天的数量与具齿原甲藻相等．2002年5月用4个围隔装置进行实验,在不同营养状况下两个种的增殖速率不同,营养盐浓度高的围隔中,中肋骨条藻的增殖速率比具齿原甲藻快得多,在营养盐限制条件下,具齿原甲藻比中肋骨条藻存活的要好。表明在营养盐丰富情况下,中肋骨条藻以其快速的繁殖在竞争中取得优势地位,导致中肋骨条藻形成的赤潮持续时间较短,消亡也快,而具齿原甲藻赤潮形成期较长,但在营养盐很低的情况下,还能维持较长时问．     

石油分散剂BP-1100X对海洋围隔生态系的影响研究

在分散剂作用下,围隔水体中浮游动物种群数量明显减少,浮游植物因捕食压力不大而诱发“赤潮”,分散的原渍在围隔水体中的生态效应变得不明显,细菌生物量和生产力在实验前期比对照组高,后期则随原油降解而波动,这表明微生物积极参与了原油的降解活动,实验揭示,由于添加物的毒性作用促成的生态系的不平衡,也可最终导致“赤潮”发生。     

石油分散剂BP-1100X对海洋围隔生态系的影响研究

在分散剂作用下,围隔水体中浮游动物种群数量明显减少,浮游植物因捕食压力不大而诱发“赤潮”.分散的原油在围隔水体中的生态效应变得不明显,细菌生物量和生产力在实验前期比对照组高,后期则随原油降解而波动,这表明微生物积极参与了原油的降解活动。实验揭示,由于添加物的毒性作用促成的生态系的不平衡,也可最终导致“赤潮”发生。     

营养盐加富和鱼类添加对浮游植物群落演替和多样性的影响

浮游植物是水体生态系统敞水区最重要的初级生产者,其组成与多样性反映了群落的结构类型和存在状态。通过围隔实验,模拟水库春季发生的营养盐加富和鱼类放养的干扰,分析在这两种干扰下的浮游植物群落演替过程中优势种和稀有种的变化,并通过以丰度与生物量为变量的香农和辛普森多样性指数的计算,分析浮游植物群落演替过程中的多样性变化特征。结果表明,营养盐加富干扰下的浮游植物群落的优势种变化和演替更为明显,营养盐加富与鱼类添加对浮游植物群落多样性变化的影响符合中度干扰理论。在优势种优势度变化较大的浮游植物群落演替过程中,多样性指数与浮游植物生物量有较高的负相关性。在浮游植物群落演替过程中,香农和辛普森多样性指数的变化趋势基本一致,采用丰度与生物量为变量的两种多样性指数的计算结果对实验系统中浮游植物群落多样性的分析结果没有明显的影响。     

南麂列岛海洋自然保护区浮游植物的种类多样性及其生态分布

于2006年5月至2007年2月之间,对南麂列岛海域的浮游植物类群进行了4个季节的调查,分析了该海域浮游植物的种类组成、优势种类、群落结构以及水平分布等特征参数的季节变化。共鉴定浮游植物80种,隶属于4个门,硅藻种类最多,甲藻其次。浮游植物可划分为3个生态类群,以广温类群为主。春季和夏季分别以三角棘原甲藻和中肋骨条藻为绝对优势种,秋冬季的优势种类组成多样化。共鉴定57种赤潮生物,占浮游植物种类数的71.25%。调查期间,三角棘原甲藻和中肋骨条藻分别于春季和夏季形成赤潮。浮游植物的物种丰富度呈现春、夏、秋、冬递减的趋势。浮游植物细胞丰度的年平均值为1.03×106cells/L,春夏季显著高于秋冬季。春季和夏季时,浮游植物高值区集中在南麂岛西北近岸海域;秋季和冬季时,浮游植物高值区相对集中在南麂岛东南近岸海域。浮游植物群落的多样性指数(H')以秋季最高,冬季最低。春季的三角棘原甲藻赤潮期间,水体中N/P值显著升高;夏季的中肋骨条藻赤潮期间,水体中N/P值显著降低。     

2006年春夏期间浙江南麂海域浮游植物群落结构特征

研究了2006年春夏期间(4~6月)浙江省南麂列岛海域的浮游植物群落结构,共观察到68种浮游植物,其中硅藻53种,甲藻13种,金藻和蓝藻各1种。调查期间,该海域浮游植物群落结构变化明显,原甲藻赤潮的形成和持续是最显著的特征,三角棘原甲藻和东海原甲藻分别在5月中、下旬先后引发赤潮。原甲藻赤潮的形成与水温有密切关系,其生消引起海水中营养盐结构的相应变化。     

围隔藻类水华演替过程中二甲基硫化物的含量动态

于2005年6月至7月,研究了海洋围隔不同藻类水华演替过程中二甲基硫化物的含量动态,并考察了相关环境参数对二甲基硫化物含量的影响。2个围隔实验组均出现未知藻水华-硅藻水华-甲藻水华的演替过程,这3次不同藻类水华分别对应了二甲基硫化物含量的3次高峰,表明藻类水华对二甲基硫化物含量有重要贡献。不同藻类水华的贡献有较大差异,甲藻水华的贡献最大,硅藻次之,未知藻类水华的贡献最小。实验结果还表明PO4^3-、NO2^-和NH4^＋主要通过影响藻类生长状态,进而影响DMSP和DMSO的含量;NO2^-和NH4^＋亦可能通过调节DMSP和DMSO在藻细胞内的生理功能,影响DMSP和DMSO的含量;PO4^3-、NO2^-和NH4^＋与DMS含量无显著相关。     

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.     

Entwicklungsgeschichte und Ultrastruktur von Pollenkitt und Exine bei nahe verwandten entomophilen und anemophilen Angiospermensippen derAlismataceae,Liliaceae, Juncaceae,Cyperaceae, Poaceae undAraceae

Some closely related members of the monocotyledonous familiesAlismataceae, Liliaceae, Juncaceae, Cyperaceae, Poaceae andAraceae with variable modes of pollination (insect- and wind-pollination) were studied in relation to the ultrastructure of pollenkitt and exine (amount, consistency and distribution of pollenkitt on the surface of pollen grains). The character syndromes of pollen cementing in entomophilous, anemophilous and intermediate (ambophilous or amphiphilous) monocotyledons are the same in principal as in dicotyledons. Comparing present with former results one can summarize: 1) The pollenkitt is always produced in the same manner by the anther tapetum in all angiosperm sub-classes. 2) The variable stickiness of entomophilous and anemophilous pollen always depends on the particular distribution and consistency of the pollenkitt, but not its amount on the pollen surface. 3) The mostly dry and powdery pollen of anemophilous plants always contains a variable amount of inactive pollenkitt in its exine cavities. 4) A step-by step change of the pollen cementing syndrome can be observed from entomophily towards anemophily. 5) From the omnipresence of pollenkitt in all wind-pollinated angiosperms studied one can conclude that the ancestors of anemophilous angiosperms probably have been zoophilous (i.e. entomophilous) throughout.

     

Identification and Characterization of the First Equine Parainfluenza Virus 5

正Dear Editor,Parainfluenza virus 5 (PIV5), known as canine parainfluenza virus in the veterinary field, is a negative-sense,nonsegmented, single-stranded RNA virus belonging to the Paramyxoviridae family (Chen 2018). The virus was first reported in primary monkey kidney cells in 1954 (Hsiung1972), then it has been frequently discovered in various     

Pathogenic Characterization and Full Length Genome Sequence of a Reassortant Infectious Bursal Disease Virus Newly Isolated in Pakistan

<正>Dear Editor,Infectious bursal disease (IBD) is one of the most important diseases of the poultry. The IBD virus (IBDV), a nonenveloped virus belonging to the Birnaviridae family with a genome consisting of two segments of double-stranded RNA (segments A and B), targets B lymphocytes of bursa of Fabricious leading to immunosuppression. In Pakistan,poultry farming is the second biggest industry and IBD is the second biggest disease threating the poultry sector.However, there is limited genome information of IBDV