苎麻疫霉有性生殖导致菌落形态和生长速率在无性后代持续变异的研究*

研究了苎麻疫霉（PhytophthoraboehmeriaeSawada）菌株JS-5自交S1代单卵孢株的菌落形态和生长速率在其单游动孢子无性系后代的遗传与变异。结果表明,亲本菌株JS-5的菌落形态和生长速率在连续4代单游动孢子无性系后代稳定遗传,而该菌株的自交S1代的约2／3单卵孢株的上述性状在其单拘无性后代中发生分离,且上述性状的分离在无性单孢后代中至少可连续保持3～4代。本研究结果提示,苎麻疫霉有性生殖导致上述性状的变异,除有性生殖过程中的基因重组外,有性生殖还诱导产生了一种新的机制参与上述性状遗传与变异的调控。本研究还观察到供试菌株及其后代所产生的游动孢子绝大多数细胞内只含有1个细胞核,表明上述机制与异核现象无关。有性生殖导致生物学性状在随后的无性后代中发生持续变异可能是苎麻疫霉生物学性状遗传多样性的重要机制之一。     

苎麻疫霉有性生殖导致菌落形态和生长速率在无性后代持续变异的研究

研究了苎麻疫霉菌株ＪＳ－５自交Ｓ１代单卵孢株的菌落形态和生长速率在其单游动孢子无性系后代的遗传与变异。结果表明,亲本菌株ＪＳ－５的菌落形态和生长速率在连续４代单游动孢子无性系后代稳定遗传,而该菌株的自交Ｓ１代的约２／３单卵孢株的上述性状在其单孢无性后代中发生分离,且上述性状的分离在无性单孢后代中至少可连续保持３￣４代。本研究结果提示,苎麻疫霉有性生殖导致上述性状的变异,除有性生殖过程中的基因重组外     

苎麻疫霉生物学性状遗传与变异研究

在实验室条件下研究了不同地区和不同寄主来源的苎麻疫霉（PhytophthoraboehmeriaeSawada）的菌落形态、菌丝线性生长速率（以下简称为生长速率）及同宗配合性状的遗传与变异,结果指出苎麻疫霉菌落形态和生长速率的遗传存在3种类型：（1）在单游动孢子后代和自交后代均可稳定遗传;（2）在单游动孢子后代稳定遗传而在自交后代发生变异;（3）在单游动孢子后代和自交后代均发生变异。结果表明,该菌菌落形态和生长速率的遗传具有多样性,上述两性状可以由细胞核杂合基因控制,也可以由细胞核纯合基因控制,还可能由细胞质因子控制。试验结果还指出,苎麻疫霉的同宗配合性状在单游动孢子和单卵孢后代均可稳定遗传,表明在供试的苎麻疫霉菌株中控制该性状的遗传因子是纯合的。     

苎麻疫霉生物学性状遗传与变异研究*

在实验室条件下研究了不同地区和不同寄主来源的苎麻疫霉（PhytophthoraboehmeriaeSawada）的菌落形态、菌丝线性生长速率（以下简称为生长速率）及同宗配合性状的遗传与变异,结果指出苎麻疫霉菌落形态和生长速率的遗传存在3种类型：（1）在单游动孢子后代和自交后代均可稳定遗传;（2）在单游动孢子后代稳定遗传而在自交后代发生变异;（3）在单游动孢子后代和自交后代均发生变异。结果表明,该菌菌落形态和生长速率的遗传具有多样性,上述两性状可以由细胞核杂合基因控制,也可以由细胞核纯合基因控制,还可能由细胞质因子控制。试验结果还指出,苎麻疫霉的同宗配合性状在单游动孢子和单卵孢后代均可稳定遗传,表明在供试的苎麻疫霉菌株中控制该性状的遗传因子是纯合的。     

掘氏疫霉遗传学研究I．自交后代(S1)生物学性状的遗传与变异

测定了掘氏疫霉Phytophthora drechsleri Tucker生长速率、菌落形态、菌体形态、产孢能力、耐35℃高温生长、致病力等生物学性状在自交S1代的遗传与变异。2个掘氏疫霉野生型菌株(A1、A2各1株)经聚碳膜间隔配对诱导自交产生的卵孢子(保存110天左右)在S+L培养基上萌发,分别获得30和35个单卵孢株(萌发率10％左右)。测定结果表明,上述生物学性状在2个亲本自交后代均发生变异,部分单卵孢株生长速度减慢、菌落形态明显改变、孢子囊和菌丝畸形、产孢能力增强、在35℃中弱生长或不生长,或致病力减弱直至无致病力。在亲本的单游动孢子无性系后代未观察到上述变异,说明上述生物学性状变异主要因亲本遗传因子的杂合性所致。从遗传学角度探讨了在自然条件下掘氏疫霉生物学性状的变异性以及某些分类依据不稳定的原因,指出有性生殖过程中的基因重组可能是引起掘氏疫霉生物学性状变异的主要原因之一。     

掘氏疫霉遗传学研究 Ⅰ.自交后代(S_1)生物学性状的遗传与变异

测定了掘氏疫霉Phytophthora drechsleri Tucker生长速率、菌落形态、菌体形态、产孢能力、耐35℃高温生长、致病力等生物学性状在自交S_1代的遗传与变异。2个掘氏疫霉野生型菌株(A_1、A_2各1株)经聚碳膜间隔配对诱导自交产生的卵孢子(保存110天左右)在S+L培养基上萌发,分别获得30和35个单卵孢株(萌发率10%左右)。测定结果表明,上述生物学性状在2个亲本自交后代均发生变异,部分单卵孢株生长速度减慢、菌落形态明显改变、孢子囊和菌丝畸形、产孢能力增强、在35℃中弱生长或不生长,或致病力减弱直至无致病力。在亲本的单游动孢子无性系后代未观察到上述变异,说明上述生物学性状变异主要因亲本遗传因子的杂合性所致。从遗传学角度探讨了在自然条件下掘氏疫霉生物学性状的变异性以及某些分类依据不稳定的原因,指出有性生殖过程中的基因重组可能是引起掘氏疫霉生物学性状变异的主要原因之一。     

苎麻疫霉生物学性状遗传与变异研究

在实验室条件下研究了不同地区和不同寄主来源的苎麻疫霉的菌落形态,菌丝线性生长速率（以下简称为生长速率）及同宗配合性状的遗传与变异,结果指出苎麻疫霉菌落形态和生长速率的遗传存在３种类型：（１）在单游动孢子后代和自交后代均可稳定遗传;（２）在单游动孢子后代稳定遗传而在自交后代发生变异;（３）在单游动孢子后代和自交后代均发生变异。结果表明,该菌菌落形态和生长速率的遗传具有多样性,上述两性状可以由细胞核杂     

掘氏疫霉遗传学研究——Ⅱ.交配型遗传与变异的研究

本研究以掘氏疫霉Phytophthora drechsleri Tucker野生型菌株的单游动孢子无性系为亲本,测定了自交、杂交后代交配型的遗传,经KMnO_4处理引起的交配型变异以及F_1代可自孕单卵孢株有性生殖后代交配型的遗传与变异。聚碳膜间隔配对诱导A_1和A_2菌株自交产生的卵孢子经H_2O_2处理刺激萌发(萌发率12～16％)获得单卵孢株。交配型测定结果表明,A_1和A_2亲本自交S_1代单卵孢株均保持与亲本一致的交配型。用KMnO_4处理上述卵孢子导致A_1和A_2亲本的部分S_1代单卵孢株出现自孕现象,少数A_1亲本自交后代改变为A_2交配型;从A_1交配型亲本的S_1代可自孕菌株产生的卵孢子萌发所建立的单卵孢株中,同时获得A_1和A_2交配型菌株。上述结果不支持Sansome关于疫霉菌A_1、A_2交配型分别由纯合、杂合基因控制的假说,进一步证明了Ko关于交配型抑制因子控制交配型表达的假说的合理性。掘氏疫霉种内菌株直接配对产生的卵孢子用H_O_2刺激萌发获得F_1代单卵孢株。测定结果表明,在F_1代出现A_1、A_2、A_1A_2、A~04种交配型的单卵孢株,其比例因不同亲本组合而有较大差异。 F_1代出现的A_1A_2菌株自孕产生的卵孢子经H_2O_2处理刺激萌发建立自交系,观察到A_1A_2交配型在有性生殖后代发生分离,各交配型比例因亲本不同而异。A_1A_2菌株的自孕能力在单游动孢子无性系后代可稳定遗传,认为F_1代出现的A_1A_2个体来自亲本的杂交。A_1A_2单卵孢株保藏4～6个月后大多仍具自孕能力,少数改变为A_2交配型。     

掘氏疫霉遗传学研究II．交配型遗传与变异的研究

本研究以掘氏疫霉P“yl口外埔o,o dr~cksleri丁ucke r野生型菌株的单游动孢子无性系为亲本,测定了自交、杂交后代交配型的遗传,经Kmno·处理引起的交配型变异以及Ft代可自孕单卵孢株有性生殖后代交配型的遗传与变异。聚碳膜间隔配对诱导A,和^,菌株自交产生的卵孢子经H zot处理索0激萌发(萌发率1 z～16％)获得单卵孢株。交配型测定结果表明,^t和A,亲本自交st代单卵孢株均保持与亲本一致的交配型。用KMnO．处理上述卵孢子导致A-和^z亲本的部分s一代单卵孢株出现自孕现象,少数A,亲本自交后代改变为A：交配型;从A。交配型亲本的s-代可自孕菌株产生的卵孢子萌发所建立的单卵孢株中,同时获得扎和^。交配型菌株。上述结果不支持San somc关于疫霉菌AhA,交配型分别由纯合、杂合基因控制的假说,进一步证明了Ko关于交配型抑制因子控制交配型表达的假说的合理性。 掘氏疫霉种内菌株直接配对产生的卵孢子用HtO,刺激萌发获得Ft代单卵孢拣。测定结果表明,在F。代出现A。A,、A,A;、A口4种交配型的单卵孢株,其比例因不同亲本组合而有较大差异oF。代出现的^。A,菌株自孕产生的卵孢子经HtO,处理刺激萌发建立自交系,观察到^。^：交配型在有性生殖后代发生分离,各交配型比例因亲本不同而异o A·At菌株的自孕能力在单游动孢子无性系后代可稳定遗传,认为F-代出现的AJAt个体来自亲本的杂交。AtA-单卵孢株保藏4～6个月后大多仍具自孕能力,少数改变为Az交配型。     

恶疫霉致病力和对甲霜灵敏感性的遗传与变异*

以分离自黑龙江腐烂苹果的恶疫霉Phytophthora cactorum Schroeter野生型菌株Ap14为亲本,采用菌丝块创伤接种法测定了恶疫霉对苹果的致病力在无性繁殖和有性生殖后代的遗传。结果是连续2代单游动孢子后代在苹果上所致病斑半径分别为22.4~24.1mm和21.8~23.4mm,与亲本所致病斑半径22.5mm无显著差异;而其20个自交后代个体所致病斑半径为21.4~25.8mm,与亲本有显著差异,其中2株致病力显著强于亲本,其余与亲本相似。表明恶疫霉对苹果的致病力在无性后代可稳定遗传,而在自交有性后代发生分离。同时在含甲霜灵0.05μg/ml的LBA平板上测定了恶疫霉菌丝生长对甲霜灵的敏感性在无性和有性后代的遗传。结果是恶疫霉对甲霜灵的敏感性在无性单孢后代无显著变异,而在50个自交有性后代中,上述浓度对其菌丝生长的抑制率分布范围为67.3~97.1%,与亲本78.3%有极显著差异,其中3株高于亲本,3株低于亲本,44株与亲本相似。表明恶疫霉对甲霜灵的敏感性同样在无性后代稳定遗传而在有性后代发生变异。上述结果提示,供试恶疫霉菌株中上述性状可能由细胞核杂合基因控制。     

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