淡水鱼池土腥异味物质含量与浮游藻类和放线菌生物量的关系

通过顶空固相微萃取-气质联用色谱测定北京市精养鱼池中两种主要土腥异味物质(土臭味素和二甲基异莰醇)含量,同时测定鱼池中浮游藻类和放线菌生物量,研究了土腥异味物质含量与浮游藻类和放线菌生物量之间的关系。结果表明,试验鱼池中土腥异味物质以土臭味素为主,土臭味素在精养鱼池中普遍存在,含量为1.22～35.58ng·L-1,二甲基异莰醇在部分鱼池中被检出,含量1.39～6.00ng·L-1。精养鱼池中共检出浮游藻类6门22属,生物量17.33～178.34mg·L-1,以硅藻和裸藻为主。放线菌共测到4个属,其中链霉菌Streptomyces sp.是主要种类,放线菌总生物量0～76×104ind.L-1。鱼池中浮游藻类总生物量与土臭味素含量正相关。浮游藻类中的颗粒直链藻Melosira granulata和条纹小环藻Cyclotella striata可能是北京地区夏秋季节淡水精养鱼池中能够产生土臭味素的主要藻类,裸藻和其他鞭毛藻类对池中异味化合物的产生可能作用较小。     

江苏滆湖浮游藻类群落结构特征

2004年4月—-2006年1月对江苏滆湖的浮游藻类进行了调查,分析了浮游藻类的群落结构、物种多样性以及浮游藻类与滆湖理化参数的相互关系。调查共鉴定出浮游藻类8f7147属267种,绿藻种类最多,其次是硅藻和蓝藻;优势种主要是铜绿微囊藻（Microcystis aeruginosa）、不定微囊藻（M.incerta）、点状平裂藻（Merismopedia punctata）、微小平裂藻（M.tenuissima）、线形棒条藻（Rhabdoerma lineare）和小空星藻（Goelastrum microporum）;总藻类密度年平均值为4871．09×10^-4 ind·L^-1,生物量年平均值为7．302mg·L^-1;密度秋季最高,生物量春、秋季较高;春季藻类物种多样性最高,多样性指数与其藻类密度负相关而与藻类生物量正相关;滆湖浮游藻类现存量由北向南逐渐减小,北部湖区与中部湖区浮游藻类现存量差异不显著,与南部湖区的差异显著,中部湖区与南部湖区间差异不显著。     

大旗瓣凤仙花的组织培养与快速繁殖

1植物名称 大旗瓣风仙花（Impatiens macrovexilla Y．L．Chen）。 2材料类别 茎上侧芽。 3培养条件 增殖培养基：（1）MS＋6-BA1．5mg·L^-1（单位下同）;继代和生根培养基：（2）MS＋6-BA1．0。以上培养基中均加入30g·L^-1蔗糖和5．5g·L^-1琼脂,pH5．8。培养温度（25±3）℃,光照时间12h·d^-1,光照强度40～50gmol·m^-2·s^-1。     

盐度对早期链霉菌产生二甲基异莰醇和土臭味素的影响

天津是中国北方重要的渔业生产基地,2006年全市水产养殖面积430 km2,水产品总产量35.5万吨,其中养殖产量30万吨,渔业产值40亿元。天津养鱼池水盐度普遍在2-5,属于寡盐水鱼池,但在该地区采取高密度精养模式生产鱼类普遍存在土腥异味,降低了水产品食用价值和养殖效益。       

蚊子花的组织培养与快速繁殖

1植物名称蚊子花（Lopezia cordata Hornem．）。 2材料类别茎段和顶芽。 3培养条件基本培养基为MS。（1）芽诱导培养基：1／2MS（MS大量元素用量减半）;（2）增殖培养基：MS＋6-BA0．2mg·L^-1（单位下同）＋NAA0．2;（3）生根培养基：I／2MS＋NAA0．5。以上培养基中均加入6g·L^-1琼脂和30g·L^-1蔗糖,pH5．9—6．0。培养室中温度为（24＋1）℃,光照时间为16h·d^-1,光照强度约为60μmol·m^-2·s^-1。     

南水北调中线干渠异味物质时空动态及其影响因素

为认识南水北调中线干渠异味物质的时空动态,于2018年9月至2019年8月对干渠沿线9个样点开展了6种异味物质、藻类群落及理化因子的逐月同步调查;结果显示:二甲基异莰醇含量平均值为(7.431±9.631)ng/L,夏季略超出嗅阈值;β-环柠檬醛和β-紫罗兰酮平均值分别为(12.371±12.800)和(11.973±...     

欧洲小叶椴的胚培养与快速繁殖

1植物名称欧洲小叶椴（Tilia cordata Mill．）。 2材料类别成熟胚。 3培养条件（1）／3动培养基：MS＋6-BA2．0mg·L^-1（单位下同）＋NAA0．1;（2）增殖培养基：MS＋6．BA1．0＋NAA0．1;（3）壮苗生根培养基：1／2MS＋IBA1．0＋NAA0．3。以上培养基均加入0．55％琼脂和20g·L^-1。蔗精,pH5．8-6．0。培养温度为（25±2）℃;光照培养时间12h·d^-1,光照强度40．50μmol·m^-2·s^-1。     

同色兜兰的组织培养与快速繁殖

1植物名称同色兜兰[Paphiopedilum concolor（Bateman）Pfitz．]。 2材料类别种子。 3培养条件种子萌发培养基：（1）MS＋100mL·L^-1香蕉汁;（2）1／2MS＋100mL·L^-1香蕉汁。原球茎继代增殖培养基：（3）1／2MS＋NAA0．2mg·L^-1（单位下同）＋100mL·L^-1香蕉汁;（4）1／2MS＋NAA0．4＋100mL·L^-1香蕉汁;（5）1／2MS＋6-BA0．5＋NAA0．2＋100mL·L^-1。     

天然水体中两种主要异嗅物质的来源及迁移转化研究进展

近年来,水中嗅味问题逐渐引起关注。研究发现,天然水体中异嗅物质主要是微生物和藻类的挥发性次级代谢产物。总结了天然水体中常见的两种异嗅物质土臭素(GSM)和二甲基异莰醇(MIB)的来源及其在生物体内的合成途径。介绍了异嗅物质通过吸附、挥发、光解、生物降解等一系列作用在饮用水水源中的迁移转化以及其进入水体生物的途径。     

湿唇兰的无菌播种和快速繁殖

1植物名称 湿唇兰[Hygrochilus parishii（Rchb.f．）Pfitz．]。 2材料类别 成熟种子。 3培养条件种子萌发培养基：（1）1／2MS;（2）1／2MS＋100mL·L^-1椰子乳;（3）KC;（4）KC＋100mL·L^-1椰子乳;（5）VW;（6）VW＋100mL·L^-1椰子乳;（7）1．5g·L^-1花宝1号＋1．5g·L^-1花宝2号;     

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