诱导玉米花粉植株的初步研究

玉米花药培养试验表明，以培养基M，为基础，补加2, 4-D2.0毫克／升和激动素1.0一2.0毫克／升，将蔗糖浓度作适当提高，即从‘％ 提高到12-24%范围，诱导花粉愈伤组织的频率可从0.52%提高到1. 03-1.09 % o夏季7-8月形成的愈伤组织没有分化出绿芽，只分化根。秋季9-11月形成的愈伤组织转入以ms为基本培养基，补加NAA 0.2-2。毫克／升和激动素0.5--2.0毫克／升灼分化培养基中，诱导出了绿芽、叶和根，并发育为绿色小植株。细胞学观察证明所获得的植株来源于花粉细胞。     

小麦花药培养中花药密度效应的初步研究

在大麦花药培养中,花药密度对花粉愈伤组织产量有明显影响。欲得大量的愈伤组织,每毫升液体培养基上需接种60枚甚至更多的花药。利用条件培养基,可提高单位体积培养基上花药有效密度,进而提高大麦花粉愈伤组织的产量。在水稻花药培养中,花粉愈伤组织产量也有随花药密度而提高的趋势。     

水稻花粉植株的诱导条件及影响诱导频率的某些因素

在离体培养条件下,测定了水稻花药中花粉愈伤组织形成的条件,并对影响花粉愈伤组织的形成和分化的某些因素进行了实验,得到以下主要结果: 1.掌握合适的花粉发育时期(单核后期接近第一次花粉分裂),在仅仅含有2毫克/升2,4-D和6％蔗糖的简单培养基上就得到了花粉愈伤组织,对于花粉细胞最初分裂的推动,生长素、碳源和渗透压是必要的条件。由无机盐、微量元素、维生素、糖及生长物质组成的复杂培养基对于花粉愈伤组织的发生和早期生长并非必需,但有利于愈伤组织的进一步生长。 2.培养基中蔗糖的作用,在于充当碳源和调节渗透压,在维持一定渗透压的条件下,过高浓度的蔗糖会抑制愈伤组织的形成。 3.椰乳、酪蛋白水解物及单核苷酸等有机附加物对花粉愈伤组织的形成及以后的器官分化都有明显的良好作用。 4.培养基中附加低浓度8p.p.m.、40p.p.m的2-氯乙基磷酸(乙烯利)和接种前在10℃下,预先处理稻穗48小时,都有明显的提高花粉愈伤组织发生频率的作用。 5.花粉愈伤组织的年龄对愈伤组织的器官分化能力有明显的影响,随愈伤组织年龄的增长而降低了花粉植株的诱导频率。     

改进水稻花药培养方法的途径

用液面漂浮方式培养水稻花药,研究了培养基的蔗糖浓度、激素成分、附加秋水仙碱对花粉愈伤组织的诱导、分化及花粉植株倍性的影响。提出改进水稻花药培养方法的途径,其要点是:用液体培养基培养花药;在培养初期,调整培养条件以增加对等核分裂花粉数和提高染色体加倍频率;在多细胞团花粉突破花粉壁生长之前,将其从开裂的花药中分离出来进行单花粉固着培养形成愈伤组织,并使愈伤组织在生长的早期转向分化。     

大麦花药培养中若干因素对愈伤组织形成的影响

在大麦花药培养中,提高花粉愈伤组织产量的关键在于低温预处理(Huang and Sunderland 1982)及花药因子(许智宏等1984)的利用。后者包括使用条件培养基或较高的接种密度。在培养基中附加较高浓度的肌醇(0.1％)亦能大幅度地提高花粉愈伤组织的产量(Xu and Sunderland 1981)。在     

诱导玉米花粉植株的初步研究

玉米花药培养试验表明,以培养基MS为基础,补加2,4-D2.0毫克/升和激动素1.0—2.0毫克/升,将蔗糖浓度作适当提高,即从6％提高到12—24％范围,诱导花粉愈伤组织的频率可从0.52％提高到1.03—1.09％。夏季7—8月形成的愈伤组织没有分化出绿芽,只分     

小麦(Triticum aestivum)雄核发育的细胞学研究

本工作对小麦花粉胚和愈伤组织的诱导条件和雄核发育的细胞学现象作了研究。结果如下:(1)N_6培养基诱导花粉愈伤组织的效果显著优于 MS 培养基。外源激素对于雄核发育的启动不是必需的,但对愈伤组织进一步的生长却是不可缺少的。(2)用花药整体制片法研究了雄核发育的各种途径,结果表明,不均等分裂和均等分裂的小孢子都能形成花粉胚,但前者占较大比例。(3)在部分多细胞花粉和白化苗中观察到染色体断片和微核,推测白化或畸形的花粉植株可能起源于具微核的花粉。(4)细胞的核内再复制和游离核的融合是产生二倍体和多倍体花粉植株的重要原因。     

桑树花粉愈伤组织的诱导与花粉细胞学研究

讨论影响桑树花粉愈伤组织诱导频率的问题 ,描述花粉细胞早期发育和愈伤组织的分化过程     

黑麦(Secale cereale L.)花药培养及其雄核发育

离体培养黑麦花药,单核花粉可以通过不等分裂和均等分裂由营养性质的核发育成花粉胚状体或愈伤组织,并且最后形成了单倍体植株。接种前对穗子进行适当的低温处理,可以有效地提高胚状体和愈伤组织的生成率。根据多核和多细胞花粉的败育情况,认为新壁的形成和花粉外壁的适时破裂是已经启动分裂的小孢子能否发育成胚状体和愈伤组织的两个关键问题。     

籼型水稻原生质体再生植株

以在MSB培养基(MS无机盐,B 5有机成份附加2mg／L 2．4－D)中继代一年的87－l籼型花粉愈伤组织和由籼型水稻株系81－3在改良的RY一2培养基中继代半年的悬浮培养物游离原生质体,分别在RY 2和KPR培养基中进行液体浅层培养或琼脂糖包埋培养,并在琼脂糖包埋培养时饲喂以粳型广亲和材料02428的悬浮培养细胞或除去}王胞的调渗悬浮液。原生质体植板率达8．7％－12．5％。将3—4周后形成的肉眼可见的小愈伤组织转移到台o．5mg／L 2．4－D的N6固体培养基上增殖,待愈伤组织长到直径达2—3mm大小时,分别或串换使用三种不同激素水平的分化培养基,最终由籼型株系81－3的原生质体再生了植株,而87－1籼型花粉胚性愈伤组织原生质体只再生了愈伤组织。     

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