白沙蒿粘液瘦果萌发中聚糖内切水解酶的活动特性

对白沙蒿 (ArtemisiasphaerocephahaKrasch .)种子萌发不同阶段的种胚提取物中几种可能降解果皮外层粘液物质的多糖内切酶进行了检测。研究结果表明 :多聚半乳糖醛酸酶在干燥胚中已存在并具较高的活性 ,但其活性随着种子吸涨及萌发而降低。此酶并不释放到种胚外。β 甘露聚糖内切酶随着种子的吸涨而增加并被萌发的种胚释放到种子外。纤维素酶在种子萌发的过程中不表现出活性。提取物中的所有多糖内切酶都无法降解果皮外层的粘液物质。     

白沙蒿粘液瘦果萌发中外切糖苷酶活动特性

白沙蒿 (ArtemisiasphaerocephalaKrasch .)是中国西北沙区分布的多年生植物。瘦果遇湿后其粘液层开始膨胀。对其种子萌发不同阶段的种胚提取物中几种可能降解果皮外层粘液物质的外切糖苷酶进行了检测。结果表明 :β 吡喃半乳糖苷酶在干种子中的活性很高 ,但是随着种子的吸涨而逐渐降低 ,在已萌发的种子中无法探测到。α和 β 吡喃阿拉伯糖苷酶、β 吡喃葡萄糖苷酶以及 β 吡喃甘露糖苷酶在种子萌发过程的胚提取物中也显示出了一些活性 ,但是这些活性在种胚外却无法探测到。所有胚提取物中的外切糖苷酶都无法降解果皮粘液物质。所有的证据都表明果皮外层的粘液物质无法在种子萌发的早期被水解。因此果皮粘液物质在干旱沙质条件下的生态功能被限制在吸收水分以及延长胚吸水的时间。     

白沙蒿粘液瘦果萌发中外切糖苷酶活动特性

白沙蒿(Artemisia sphaerocephala Krasch.)是中国西北沙区分布的多年生植物.瘦果遇湿后其粘液层开始膨胀.对其种子萌发不同阶段的种胚提取物中几种可能降解果皮外层粘液物质的外切糖苷酶进行了检测.结果表明:β-吡喃半乳糖苷酶在干种子中的活性很高,但是随着种子的吸涨而逐渐降低,在已萌发的种子中无法探测到.α和β-吡喃阿拉伯糖苷酶、β-吡喃葡萄糖苷酶以及β-吡喃甘露糖苷酶在种子萌发过程的胚提取物中也显示出了一些活性,但是这些活性在种胚外却无法探测到.所有胚提取物中的外切糖苷酶都无法降解果皮粘液物质.所有的证据都表明果皮外层的粘液物质无法在种子萌发的早期被水解.因此果皮粘液物质在干旱沙质条件下的生态功能被限制在吸收水分以及延长胚吸水的时间.     

不同成熟度花生胚萌发时子叶中贮藏蛋白质的降解

花生(Arachis hypogaea L.)汕油71果针入土20d(20 DAP)的种子剥去种皮后,10％的胚可以萌发,至40 DAP发芽率达98％。不同发育时期的花生胚萌发 10d后子叶盐溶蛋白质和花生球蛋白降解表明,20和32 DAP胚萌发后,子叶中这些蛋白质只有部分降解。随着胚成熟度增加,子叶中降解这些蛋白质的能力不断提高。20～40 DAP胚萌发4d时,子叶的BAPAase和GHE活性较低。50～80DAP胚萌发 4d,子叶中上述两种酶均显示较高的活性。     

外磁场对小麦萌发期过氧化物酶合成的影响及其激活效应

外磁场处理小麦种子可以提高萌发期过氧化物酶(POD)的活性;电泳图谱中,磁场透发出两条(POD)同工酶新带。在萌发初期(12h),亚胺环己酮(CHM)对外磁场提高POD活性的作用影响很小,外磁场可使POD酶蛋白的比活力增长,表明在萌发初期,磁场对种胚内的POD可能具有活化作用。萌发1d后,CHM逐渐削弱外磁场对POD活性的提高作用,而放线菌素D(AMD)则无影响。     

白沙蒿种子萌发特性的研究 I. 粘液瘦果的结构和功能

白沙蒿(Artemisia sphaerocephala Krasch.)是中国西北部沙漠的流动及固定沙丘上广泛分布的优势种灌木。瘦果小而轻,借助显微镜和扫描电镜对瘦果的形态结构进行了观察,其种子的种皮与果皮愈合,果皮外层为很厚的粘液层,其粘液层在遇湿后迅速吸水膨胀,其重量增至原来的589倍。在自然生境中,粘液物质将沙粒粘附于瘦果的周围,使瘦果的重量发生变化。瘦果能长时间在水上漂浮,粘液物质有助于种子的萌发和苗的发育。白沙蒿产生三种不同颜色的瘦果,其种子具有不同的萌发速率但最终达到相同的萌发率。研究表明瘦果的粘液物质对白沙蒿种子的传播与萌发具有重要的生态意义。     

粘液繁殖体种子的粘液质形成、分泌及释放相关基因

种皮粘液质是在种皮外层细胞的高尔基体内产生并分泌到胞腔内或细胞壁层的一种果胶类多糖物质.当干燥种子遇水后,粘液质即刻被释放形成透明胶质并完全包被整个种子.粘液质对种子的扩散定居、种子萌发以及幼苗的存活和生长均具有重要作用.粘液质作为一种模型研究细胞壁的产生及其形成的分子机制已经成为植物种皮发育与环境变化相适应关系的研究...     

白沙蒿种子萌发特性的研究Ⅰ．粘液瘦果的结构和功能

白莎蒿（Ａrtemisia sphaerocephala Krasch.)是中国西北部沙漠的流动及固定沙丘上广泛分布的优势种灌木。瘦果小而轻,借助显微镜和扫描电镜对瘦果的形态结果进行了观察,其种子的种质与果皮愈合,要皮外层为很厚的粘液层,其粘液层在遇湿后迅速吸水膨胀,其重量增至原来的５８９倍。在自然生境中,粘液物质将沙粒粘附于瘦果的使瘦果的重量发生变化。瘦果能长时间在水上漂浮,粘液物质有助于种子的萌发和苗的发育。白沙蒿产生三种不同颜色的瘦果,其种子具有不同的萌发速率但最终达到相的萌发率。研究表明：瘦果的粘液物质对白沙蒿种子的传播与萌发具有重要的生态意义。     

小麦种子成熟和萌发过程中的假萌发素活性

用SDS-PAGE方法研究了假萌发素(ψG)在小麦种子成熟和萌发过程中活性的变化.结果表明:在种子成熟过程中只有ψG表达,扬花后10 d,在颖壳、内外桴、种皮和果皮中皆可检测到ψG的草酸氧化酶活性,随着发育进程的推进,ψG的活性增大.在种子萌发过程中,在小麦品种中育5号的维管束过渡区中除了萌发素G和G'外,还可检测到ψG的草酸氧化酶活性.由于ψG在种子成熟过程中主要存在于颖壳、内外桴、果皮及种皮这些保护组织中,且开始大量表达的时间正是生长接近停止时,于是推测ψG很可能通过降解草酸产生H2O2而推动这些组织细胞壁的木质化.     

梣叶槭种子中抑制物质研究简报

休眠、层积和萌发的梣叶槭种子中抑制物质的含量不同。休眠的种子中抑制物质的含量最多,层积后的种子抑制物质活性明显减弱,萌发的种子中依然存有少量的抑制物质。抑制物质在种子内的分布也不同。子叶内较多,胚中较少。种子萌发时,胚内的抑制物质可能向子叶转移。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

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.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.