湛江球形棕囊藻赤潮除藻试验

2005年4月,在广东湛江港赤潮区采集球形棕囊藻(Phaeoecystisglobosa),在室内用新洁尔灭和异噻唑啉酮两种除藻剂进行棕囊藻的杀灭试验。结果表明,新洁尔灭对赤潮水体中球形棕囊藻的72hLC50为0.96mgL-1;与新洁尔灭相比,异噻唑啉酮的除藻效果更为明显,其对球形棕囊藻的72hLC50为0.54mgL-1。新洁尔灭和异噻唑啉酮复配时具有协同作用,可提高除藻能力,新洁尔灭和异噻唑啉酮浓度比为1.3:0.3(配比为4.3:1)时除藻效果最优,2d的除藻率达到89%,协同指数为0.78。两种除藻剂对鲻鱼(Mugilcephalus)苗72h的毒性试验表明,新洁尔灭和异噻唑啉酮浓度分别在2.0和0.3mgL-1以下除藻是安全的。     

球形棕囊藻对五种水生动物的急性毒性作用

利用室内半静水法研究球形棕囊藻培养液、藻细胞悬浮液、去藻细胞滤液、藻细胞内容物、藻细胞碎片以及溶血毒素粗提物对卤虫(Artemia sinica)、褶皱臂尾轮虫(Brachionus plicatilis)、蒙古裸腹潘(Moina mongolia)、赤点石斑鱼幼鱼(Epinephelus akaara)和南美白对虾(Penaeus vannamei)5种水生动物的影响,并对其致毒途径进行分析.结果表明,与对照相比,培养液、藻细胞悬浮液处理卤虫,其运动速度下降,培养液、藻细胞悬浮液与毒素粗提物处理轮虫72 h,存活率显著降低(P＜0.05),卤虫、轮虫消化道中充满藻细胞,提示摄食球形棕囊藻可能是引起卤虫、轮虫中毒的主要途径.培养液、滤液和藻细胞内容物对赤点石斑鱼幼鱼均有显著的致死作用,而藻细胞碎片和溶血毒素粗提物对幼鱼的存活无明显影响,表明球形棕囊藻细胞表面并不存在毒性物质,球形棕囊藻可能会分泌有毒物质进入水体,进而影响鱼类的生长.培养液、藻细胞悬浮液、去藻细胞滤液、毒素粗提物处理蒙古裸腹溞72 h虽有死亡,但存活率与对照无显著差异;南美白对虾的情况与蒙古裸腹溞类似,表明球形棕囊藻及相关组分对蒙古裸腹溞和对虾的影响较小.这些结果表明,球形棕囊藻对不同生物的毒害作用不同;摄食和分泌有毒、有害物是球形棕囊藻引致生物中毒的主要途径;除了溶血毒素以外,球形棕囊藻还可能产生其他鱼毒性物质.     

镉和十二烷基硫酸钠对克氏原螯虾的单一和联合毒性

采用静水生物测试法,研究了十二烷基硫酸钠(SDS)和Cd2+对克氏原螯虾的单一和联合毒性效应。结果表明,SDS对克氏原螯虾24、48、72和96h的半致死浓度(LC50)分别为1365.60、1171.72、1128.43和1120.43mg·L-1,安全浓度(SC)为258.79mg·L-1;Cd2+对克氏原螯虾24、48、72和96h的LC50分别为1197.09、142.06、90.85和82.64mg·L-1,SC值为0.6mg·L-1。SDS和Cd2+对克氏原螯虾的毒性分别为低毒和高毒,毒性大小为Cd2+>SDS。联合毒性试验表明,二者毒性比为1∶1,暴露时间为24、48、72和96h时,相加指数(AI)分别为0.335、0.017、0.030和0.032,联合作用结果均为毒性增强的协同作用。     

有害赤潮生物球形棕囊藻对卤虫的毒性研究

利用1997年10月和1998年6月分别在广东汕头饶平海域和香港海域分离到的球形棕囊藻,即球形棕囊藻香港株(Phaeocystis globosastrain HK)和球形棕囊藻汕头株(Phaeocystis globosastrain ST),在实验室条件下研究其对四日龄卤虫(Artemia sinica)的急性毒性。结果表明,对数生长期的HK株藻液24h对卤虫LC₅₀约为2.9×10⁵cell·mL^-1。对数期的ST株对卤虫的毒性难以达到半致死浓度,衰亡期的ST株24h对卤虫LC₅₀约为9.89×10⁶cell·mL^-1。在上述浓度下两者半致死时间分别为20.91h和26.62h,而对数生长期的HK株和衰亡期的ST株的培养物过滤液24h对卤虫LC₅₀则分别为7.1×10⁵cell·mL^-1和1.457×10⁷cell·mL^-1,且在该浓度下的半致死时间分别为26.56h和28.02h。实验表明,HK株藻液和滤液的毒性均大于ST株,且藻液的毒性均大于滤液。     

二氧化氯对球形棕囊藻的抑制和杀灭作用

以海洋赤潮生物-球形棕囊藻汕头株(Phaeocystis globosa,ST strain)为材料,研究了ClO2对不同起始藻密度的棕囊藻的抑制和杀灭作用．结果表明,ClO2对球形棕囊藻有明显的抑制和杀灭作用．藻密度为2．35×10^9cells·L-1时,高于0．74×10-2mmol·L-1的ClO2对棕囊藻生长有一定的抑制作用。高于2．96×10-2mmol·L-1的ClO2对棕囊藻具有显著的杀灭作用．藻密度与ClO2浓度之间存在一定的剂量关系．藻密度为2．35×10^9、1．18×10^9、4．70×10^8、1．18×10^8 cells·L-1时。其96h的有效杀藻浓度分别为2．96×10^-2、2．22×10^-2、1．48×10^-2和0．59×10^-2mmol·L^-1．藻密度越高。杀灭单位藻细胞所需ClO2的浓度越低．ClO2作为杀藻剂在赤潮治理中具有很好的应用前景．     

东湖茶港排污口底泥对稀有

以东湖茶港排污口底泥复溶水为试验相,采用96h急性毒性试验和胚胎-卵黄囊吸收阶段毒性试验方法,研究了东湖茶港排污口底泥对稀有(鱼句)鲫的毒性.结果显示,高浓度的复溶水对稀有(鱼句)鲫胚胎、仔鱼和幼鱼具有明显的毒性效应,而胚胎-卵黄囊吸收阶段更为敏感.随着复溶水浓度的增加,稀有(鱼句)鲫受精卵孵化率降低,仔鱼畸形率增高、成活率降低、生长减慢;对胚胎-卵黄囊吸收阶段的NOEC、LOEC和MATC分别为12.5%、25%和17.68%;对幼鱼96h LC50为69.1%.本文的研究还表明,底泥经晾晒后毒性大幅降低,暗示恢复东湖通江状态并让水位自然涨落,可能有助于缓解污染、恢复生态环境.     

军曹鱼淋巴囊肿病毒主衣壳蛋白基因全序列分析

军曹鱼(Rachycentron canadum)亦称海鲡,是我国南方沿海一带的重要海水网箱养殖对象。2005年8月,广东省海水网箱养殖的军曹鱼首次暴发类似的淋巴囊肿病,病鱼的口唇、鳃、鳍、尾及体表等处,可看到大小不一的单个或成群的肿瘤,个别网箱的感染率在80%以上,死亡率近30%。病鱼形象丑陋,严重影响其市场价值,造成了较大的经济损失。淋巴囊肿病(Lymphocystis disease)发现于1874年,1965年正式确认该病病原为淋巴囊肿病毒[1],现已知可感染9目34科140种以上鱼类。我国在20世纪90年代陆续在养殖石斑鱼、鲈鱼、牙鲆中发现淋巴囊肿病[2-5],随后对其病原…     

大型海藻龙须菜对浮游植物群落结构影响的实验研究

2008年3月采用室内中型受控系统,开展了大型海藻龙须菜(Gracilaria lemaneiformis)对浮游植物群落结构影响的实验研究.实验培养池为9个2 m×0.7 m×1 m的培养池,注入1 000 L沙滤海水.实验设置3个处理组:对照组(未添加龙须菜)、3 kg龙须菜组和6 kg龙须菜组,每组3个平行,实验周期为10 d.结果表明,未添加龙须菜的对照组发生了中肋骨条藻赤潮,水体浑浊并伴有恶臭,浮游植物细胞密度峰值为3.88×107cells·L-1,叶绿素a浓度峰值为43.87 μg·L-1;3 kg和6 kg龙须菜处理组水体浮游植物细胞密度最高值分别为3.78×106cells·L-1和1.33×107cells·L-1,叶绿素a浓度最高值分别为15.16 μg·L-1和6.69 μg·L-1,均显著低于对照组(p≤0.01).龙须菜处理组浮游植物种类较多,群落结构较稳定.大型海藻龙须菜作为富营养化水体生物修复材料,可有效提高水质和防治赤潮.     

几种杀虫剂对西花蓟马的室内毒力

用浸渍法进行了7种杀虫剂对西花蓟马成虫和若虫的室内毒力测定。结果表明,多杀霉素(48 h)、甲氨基阿维菌素苯甲酸盐(48 h)、阿维菌素(48 h)、辛硫磷(24 h)对西花蓟马成虫的LC50值为0.0544-3.1573 mg.L-1,对西花蓟马若虫的LC50值为0.0219-1.0905 mg.L-1,是防治西花蓟马的较好药剂。     

海洋酸化条件下铜、镉对日本虎斑猛水蚤的急性毒性效应

以日本虎斑猛水蚤(Tigriopus japonicus)为试验生物,采用高纯度CO2和空气的混合气体调配试验所需酸化海水(pH值7.70、7.30、6.50),研究不同海水酸化条件下铜、镉对海洋生物的急性毒性效应。结果表明:单一CO2酸化海水对日本虎斑猛水蚤存活的影响不显著;海水酸化对铜和镉急性毒性的影响效应有差异。铜在低pH值(6.5)时对日本虎斑猛水蚤的毒性最强,96h LC50浓度为0.64 mg/L,明显低于pH值为8.0、7.7、7.3对日本虎斑猛水蚤的96h LC50浓度,其分别为1.98,1.19,1.05 mg/L,随pH值下降,96h LC50下降了近3倍。海水酸化使镉的96h LC50略呈下降趋势,但对其急性毒性影响效应并不显著;pH值为7.7和7.3时,铜的安全浓度分别为11.9、10.5μg/L,接近于中国海水二类水质标准。本研究表明随着海洋酸化的进程我国近海水域将面临铜污染加剧的威胁。     

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