乌蕨孢子萌发研究

用随机区组试验和方差分析方法,研究了培养温度、贮藏温度、GA处理和光照强度对乌蕨(Sphe-nomeris chinensis)孢子萌发的影响。与室温(20～25℃)相比,培养温度在28℃时,孢子最大萌发率相近而萌发速率明显较高。贮藏温度(A)极显著(P<0.01)影响孢子萌发率,-20℃贮藏降低萌发率;GA(B)对孢子萌发率无显著影响。光照强度(C)极显著(P<0.01)影响孢子萌发率,充足光照和弱光照无显著差异,黑暗处理降低萌发率。A×B,A×C,B×C及A×B×C交互效应不显著。     

乌蕨孢子萌发研究

用随机区组试验和方差分析方法, 研究了培养温度、贮藏温度、GA 处理和光照强度对乌蕨( Sphenomeris chinensis) 孢子萌发的影响。与室温(20～25℃ ) 相比, 培养温度在28℃时, 孢子最大萌发率相近而萌发速率明显较高。贮藏温度(A) 极显著( P < 0 . 01 ) 影响孢子萌发率, - 20℃ 贮藏降低萌发率; GA (B) 对孢子萌发率无显著影响。光照强度(C) 极显著( P < 0.01) 影响孢子萌发率, 充足光照和弱光照无显著差异, 黑暗处理降低萌发率。A×B, A×C, B×C 及A×B×C 交互效应不显著。     

苹果炭疽菌低毒性菌株生物学特性的研究

研究了温度、pH值及碳源对苹果炭疽病菌(Colletotrichum gloeosporioides)强毒性菌株及低毒性菌株的生长、产孢和孢子萌发的影响。结果表明:菌丝生长温度范围10℃~35℃、最适温度为28℃,低毒菌株生长速率较快,产生分生孢子的温度范围与分生孢子萌发的温度范围为15℃~35℃,低毒菌株孢子萌发率较高,菌丝生长的最适pH值基本相同,pH在3~10的范围内均能生长和产孢,产生分生孢子的最适pH值为4~5,但经离子注入的低毒性菌株C100-2-5的产孢量在不同的pH值和温度下却一直低于经磁场处理的C0.25-1-2和强毒性菌株(对照)。分生孢子的致死温度为47℃、15 min或50℃、5 min。但菌丝的致死温度却不同,对照为60℃、20 min,C0.25-1-2为60℃、25 min,C100-2-5为60℃、30 min,65℃下5 min(及5 min以上)。     

雪腐核盘菌菌核的萌发条件与致死温度

菌核是核盘菌Sclerotinia spp.在土壤中的主要存活形式和菌核病的主要初侵染源,在土壤中可存活8年以上,其数量和存活状况直接影响着菌核病的发生和危害程度。本研究以雪腐核盘菌Sclerotinia nivalis菌株SS-TB为材料,分析了菌核萌发的影响因素、致死温度以及土壤温度对菌核存活的影响。结果表明,未成熟菌核较成熟菌核更容易萌发;菌核萌发的最佳温度为20-25℃、pH为3.0-4.0、土壤含水量为20%-45%。菌核长时间浸泡水中对其存活不利,浸泡30d以后,存活率开始急剧下降,至47d时存活率为0。雪腐核盘菌菌核具有较强的耐高温特性,随着温度和处理时间的增加,菌核萌发率呈下降趋势。菌核在水浴中85℃ 5min、80℃ 10min、75℃ 10min、70℃ 30min、65℃ 120min、60℃ 180min时全部丧失活力。在土壤温度30℃和35℃处理5周、40℃和45℃处理4周时菌核全部失去活力。该研究结果为通过水旱轮作和土壤高温处理来防治西洋参菌核病提供了理论基础。     

甘蓝根肿病菌的生物学特性研究*

对甘蓝根肿病菌生物学特性研究表明,该菌休眠孢子萌发的最适温度24℃,最适pH值6.0～6.7,致死温度45℃,肿根腐烂处理可以显著提高萌发率,光对休眠孢子萌发有明显抑制作用。该菌休眠孢子在感病寄主的根分泌物溶液中萌发率最高,达75%。耐病甘蓝品种及番茄的根分泌物均能刺激休眠孢子萌发。通过电镜观察,根肿病菌休眠孢子为近球形,孢壁有乳状突起,直径2.1～3.1mm(平均直径2.5mm)。游动孢子为近球形或椭圆形,大小为1.6～3.6mm,同侧着生不等长尾鞭式双鞭毛。     

甘蓝根肿病菌的生物学特性研究

对甘蓝根肿病菌生物学特性研究表明,该菌休眠孢子萌发的最适温度24℃,最适pH值6.0-6.7,致死温度45℃,肿根腐烂处理可以显著提高萌发率,光对休眠孢子萌发有明显抑制作用。该菌休眠孢子在感病寄主的根分泌物溶液中萌发率最高,达75％,耐病甘蓝品种及番茄的根分泌物均能刺激休眠孢子萌发。通过电镜观察,根肿病菌休眠孢子为近球形,孢壁有乳状突起,直径2.1-3.1μm（平均直径2.5μm)。游动孢子为近球形或椭圆形,大小为1.6-3.6μm。同侧着生不等长尾鞭式双鞭毛。     

芹菜斑枯病菌生物学特性研究

以沈阳地区芹菜斑枯病菌的纯培养菌株为试材,通过对菌丝生长、孢子萌发的营养及环境条件的多因子试验,明确了芹菜斑枯病菌菌丝生长以在CDAMS—VI培养基上最好,其次是CSA、CCSA和PDA,菌丝生长及产孢对碳源、氮源种类有明显的选择性。菌丝生长的最适pH值为4～5,最适温度为21℃,致死温度为39℃（处理40min）,光照明显抑制菌丝生长。病菌分生孢子在水和芹菜汁中不能萌发,在水琼脂上萌发最好;孢子萌发的适宜pH值为4．6～6．6,适温为17—25℃,致死温度为42℃（处理20min）,RH100％最适宜孢子萌发。光照和变温处理可促进分生孢子器的形成,病菌在PDA上从孢子萌发到分生孢子器形成并释放出分生孢子需要16～18d。     

储藏和萌发温度对青藏高原东缘12种灌木种子萌发的影响

研究了青藏高原东缘2个储藏条件下的12种灌木种子在10、15、20、25℃恒温培养下和5/25℃变温培养下的萌发特性及其与种子大小和生境的关系。结果表明:12种灌木室内干储种子在5/25℃变温培养下种子平均萌发率最高、萌发速率最快,室外埋藏种子10℃、5/25℃下种子平均萌发率相近且最高,但萌发速率5/25℃最快,10℃下最慢,4个恒温下的室内干储和室外埋藏种子的萌发速率均随温度升高而变快;10、15、20和25℃恒温培养下的室外埋藏种子平均萌发率、平均萌发速率均高于室内储藏,而5/25℃变温下则是室外埋藏种子平均萌发率、平均萌发速率均低于室内储藏;室内干储的12种灌木种子在5/25℃变温下的萌发率、萌发速率与种子大小呈显著负相关,而室外埋藏的种子在10℃以及5/25℃变温下的萌发率、萌发速率与种子大小均呈显著负相关,20℃下,只有萌发速率与种子大小呈显著负相关;其他储藏和温度下的萌发率、萌发速率与种子大小均没有显著相关;无论室内干储还是室外埋藏,阳坡灌丛物种在5个温度下的萌发率、萌发速率均显著高于阴坡灌丛物种,阴坡灌丛种子萌发率随温度升高而降低;变温有利于种子萌发,贮藏条件对种子的萌发特性的影响具有变温依赖性,种子的萌发特性与种子大小以及生境的关系具有明显的培养温度和储存条件依赖性。     

影响水稻稻瘟病菌侵染过程的生态因子研究

通过田间和室内模拟等方法研究了水稻生长阶段,品种抗性,温度,降雨量和施N量等因子对稻瘟病菌侵染过程的影响。结果表明,水稻叶表单位面积病菌孢子附着量与水稻不同生长阶段呈负相关关系。稻瘟病潜育期与温度关系密切,在10℃-33℃范围内,以28℃条件下潜育期最短,小于℃,大于28℃的潜育期相应延长;病菌孢子侵染比值与水稻生长阶段呈负相关关系;稻叶表病菌孢子附着率在孢子与叶表接触后的5h内,与降水强度和降水持续时间密切相关,5h后影响变小;在一定条件下,稻瘟病扩展性病斑与非扩展性病的比值,扩展性病斑扩展的最大面积与水稻品种抗性和当时病斑所处叶位有关。     

不同温度下PEG-6000模拟干旱对柠条锦鸡儿种子萌发的胁迫效应

在人工气候箱控制的不同温度(10、15、20、25℃和30℃)下,设置聚乙二醇(PEG-6000)质量百分比浓度分别为0%、5%、10%、15%、20%、25%和30%的7个模拟干旱胁迫处理,研究了柠条锦鸡儿(Caragana korshinskii Kom.)种子的萌发特性。结果表明:(1)温度和PEG模拟干旱胁迫及二者的交互作用对柠条锦鸡儿种子的萌发率、萌发速率系数、萌发值、萌发指数和活力指数均具有极显著影响(P0.01)。(2)种子萌发率在15℃下最大,显著大于10℃下的(P0.01),随着温度的继续升高逐渐减小;萌发速率系数随着温度的升高有减小的趋势,30℃下又显著增大;萌发值和萌发指数分别在25℃和20℃下最大,但均随温度的继续升高而显著减小(P0.05);活力指数随着温度的升高而减小,除在10℃和20℃间无显著差异外,其他温度间均差异显著(P0.05)。(3)种子萌发率、萌发值和萌发指数在15℃下与PEG浓度呈不显著的负相关关系,而在其他温度下均与PEG胁迫浓度显著负相关(P0.05),且相关系数均在25℃或30℃下最大;萌发速率系数在各温度下均与PEG胁迫浓度显著正相关;活力指数与PEG胁迫浓度呈显著负相关,相关系数随着温度的升高逐渐增大。(4)萌发参数与PEG胁迫浓度间的回归模型表现为三次曲线、二次曲线和直线模型3种类型,其中以三次曲线模型为主,全部回归模型均达到显著性水平(P0.05);在20℃以下的温度条件下,较低浓度PEG处理对柠条锦鸡儿种子萌发具有一定的促进作用,在15℃下种子萌发对PEG模拟干旱胁迫的耐受性最强;柠条锦鸡儿种子在不同温度和干旱胁迫下的萌发模式是对其分布区生境长期适应和进化的结果。     

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.