烟草愈伤组织分化和芽原基形成期间呼吸代谢途径的改变

接种在继代培养基上的柳叶烟草愈伤组织,未观察到组织分化和芽原基形成。在分化培养基上生长的愈伤组织,接种后第6天可见拟分生组织和管胞分化,9—12天有芽原基形成,15—18天可观察到苗端结构。根据碘乙酸、Na_3PO_4和丙二酸抑制试验,以及3-磷酸甘油醛脱氢酶与琥珀酸脱氢酶活性测定结果,初步表明烟草愈伤组织呼吸中存在有EMP、HMP和TCAC代谢途径.在发生输导组织和芽原基分化的愈伤组织中(接种后第6—12天),HMP途径的运行程度较高;而芽原基的继续生长(培养12天以后),则与EMP途径的增加有关;分化培养基上生长的愈伤组织,始终较继代培养愈伤组织具有较高的FCAC活性水平。     

柳叶烟草愈伤组织分化期间抗氰呼吸的改变

继代培养的柳叶烟草愈伤组织有明显的抗氰呼吸。交替途径的相对贡献约占总呼吸的29—38%;但仍以细胞色素途径为主,约占总呼吸的44—51%。接种在分化培养基上的愈伤组织在发生组织分化和芽原基形成期间,交替途径运行量占总呼吸的41—47%,承担呼吸电子传递的主要部分;而细胞色素途径只占总呼吸的29—32%。交替途径运行程度的增高可能与烟草愈伤组织的分化有一定相关性。     

烟草愈伤组织继代培养与分化期间核酸代谢的比较研究

柳叶烟草愈伤组织在分化和芽原基形成期间,DNA 和RNA 含量均高于继代培养物;在芽原基形成后和幼芽生长期间(12天以后),DNA和RNA 含量持续上升,而同期继代培养物巳进入生长静止期,DNA 和RNA 含量基本不变或略有下降。根据RNA 电泳结果还进一步分析了两种愈伤组织培养物各RNA 组分变化与总RNA 含量变化的关系。分化培养物在芽原基形成时有明显升高的RNase 活性峰和持续上升的RNA 合成速率;而此时期继代培养物的RNase 活性及RNA 合成能力均较低;分化愈伤组织的DNA 合成速率在幼芽生长期间仍维持上升趋势,且显著高于同期继代愈伤组织的合成速率。这些结果表明,烟草愈伤组织分化培养物比继代培养物有更旺盛的核酸代谢能力。     

烟草愈伤组织多酚氧化酶研究

柳叶烟草愈伤组织中多酚氧化酶氧化邻苯二酚的活性明显高于氧化对苯二酚的活性。当以邻苯二酚为底物时,烟草愈伤组织多酚氧化酶分别在pH 5.6和pH 7.4有两个活性高峰。KCN、Dieca和m-CLAM对烟草愈伤组织多酚氧化酶活性都有明显抑制效应。根据凝胶电泳分析,继代培养愈伤组织多酚氧化酶同工酶有5条酶带,而巳分化出芽原基的愈伤组织和新分化长出的小叶都有7—8条酶带。继代培养的愈伤组织多酚氧化酶主要存在于除去线粒体的上清液中,线粒体部分也可测出酶活性。继代培养愈伤组织在接种后18天内,多酚氧化酶活性无重大改变。在此期间,Dieca对呼吸的抑制效应也变化不大。分化组织多酚氧化酶活性显著高于继代培养愈伤组织,在芽原基形成后,酶活性明显升高;此时Dieca对呼吸的抑制也由32%上升到47%。     

硝酸银对离体培养烟草叶片愈伤组织形成和芽再生及其脯氨酸和丙二醛含量的影响(简报)

培养基中添加不同浓度硝酸银离体培养烟草叶片的结果表明,1～5mg·L-1硝酸银可提高烟草愈伤组织的芽分化率,5 mg·L-1硝酸银对芽再生的促进作用最佳,而高于10mg·L-1的硝酸银抑制愈伤组织的形成和芽再生.在愈伤组织和再生芽中,脯氨酸和丙二醛含量均随硝酸银浓度的增加而增加.     

烟草愈伤组织器官发生过程中外源激素的作用

近年来,利用愈伤组织系统在与器官发生有关的形态学、生理学和生物化学研究方面已经取得了一些进展(Thorpe 1980,刘涤 1983)。对烟草愈伤组织系统的研究明确了外源激素对器官发生类型的调节作用(Skoog 1971,Engelke等1973,刘涤等1980)。但是,这些研究仅考虑到外源激素的作用,而对器官发生过程中的其它变化并不了解。最近,Kamada和Harada(1981)比较了胡萝卜体细胞胚发育过程中内源IAA和ABA含量的变化,Noma等(1982)证实形成胚的和不形成胚的细胞间GA_3含     

烟草愈伤组织继代培养期间呼吸途径与活性氧水平动态变化

继代培养期间的烟草愈伤组织总呼吸速率分别在第11天和第19天出现两次跃升,同时抗氰呼吸的发生与运行逐渐加强,在两呼吸高峰之间达到极大值,随后则逐渐下降,但愈伤组织的电子传递仍以细胞色素途径为主．通过对愈伤组织衰老过程中活性氧代谢变化分析,发现抗氰呼吸发生与H     

头孢霉素类抗生素在转基因烟草中作用的初步研究

研究了头孢曲松钠、头孢哌酮钠、头孢西林钠、头孢唑林钠、头孢拉定5种头孢霉素类抗生素对农杆菌EHA105的抑制作用和对烟草愈伤组织的诱导及丛生芽形成的影响,结果表明：5种头孢类抗生素在作为抑菌剂用于烟草遗传转化试验时,头孢曲松钠的抑菌效果最好,浓度以200mg/L为宜,同时该抗生素在低浓度下能提高愈伤组织诱导率和丛生芽诱导率,在高浓度下则抑制愈伤组织和芽的形成 ,有类似植物激素的活性。     

金鱼草愈伤组织过氧化物酶活性及其同工酶变化

在不同激素比例的MS培养基上 ,金鱼草 (Antirrhinummajus)茎愈伤组织主要有三种分化状态 :a愈伤组织不分化 ;b以器官发生途径分化出不定芽和不定根 ;c通过胚胎发生途径形成胚状体。过氧化物酶活性与愈伤组织分化程度呈正相关。未分化愈伤组织与分化芽、分胚状体及分化芽和根的愈伤组织酶活性呈线性递增关系 ,相对酶活力为 1:3:5 :6。在其同工酶谱中 ,三种状态的愈伤组织都具有酶带I和II,表明这两种同工酶与细胞的增殖生长有联系。分化的愈伤组织比未分化愈伤组织多出现酶带Ⅲ、Ⅳ和Ⅴ ,说明这三条酶带是影响分化的特异蛋白质。在分化芽的愈伤组织中 ,还存在酶带Ⅳ ,说明它是催化器官发生途径的特有同工酶。     

细枝木麻黄离体培养过程中愈伤组织和再生芽的细胞组织学观察

为探讨细枝木麻黄(Casuarina cunninghamianaMiq.)愈伤组织分化过程的细胞组织学,对离体培养条件下的愈伤组织进行扫描电子显微镜和石蜡切片观察,分析愈伤组织的细胞分裂、分化以及芽再生的发生过程。结果表明,新鲜外植体培养于愈伤组织诱导培养基上,伤口处的薄壁细胞开始脱分化,培养1周后形成明显的愈伤组织;继续培养2周后,胚性愈伤组织形成,且表层细胞启动分化形成芽原基;培养4周,可肉眼观察到胚性芽原基,数量增多并逐渐分化形成不定芽;培养至第6周,生成不定芽,并大量增殖和分化。因此,细枝木麻黄是通过愈伤组织分化形成胚状体的途径进行植株再生的,为建立细枝木麻黄组织培养高效再生体系提供了理论依据。     

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.     

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.     

Synthesis and antimicrobial studies of hydrazone derivatives of 4-[3-(2,4-difluorophenyl)-4-formyl-1H-pyrazol-1-yl]benzoic acid and 4-[3-(3,4-difluorophenyl)-4-formyl-1H-pyrazol-1-yl]benzoic acid

Microbial resistance to antibiotics is an unresolved global concern, which needs urgent and coordinated action. One of the guidelines of the Centers for Disease Control and Preventions (CDC) to combat antibiotic resistance is the development of new antibiotics to treat drug-resistant bacteria. In our effort to find new antibiotics, we report the synthesis and antimicrobial studies of 30 new pyrazole derivatives. These novel molecules have been synthesized by using readily available starting materials and benign reaction conditions. Some of these molecules have shown activity with MIC values as low as 0.78?µg/mL against four bacterial strains; Staphylococcus aureus, methicillin-resistant S. aureus, Bacillus subtilis, and Acinetobacter baumannii. Furthermore, active molecules are non-toxic to mammalian cell line.

     

Novel compounds with potent CDK9 inhibitory activity for the treatment of myeloma

Cyclin-dependent kinases (CDKs) and Polo-like kinases (PLKs) play key role in the regulation of the cell cycle. The aim of our study was originally the further development of our recently discovered polo-like kinase 1 (PLK1) inhibitors. A series of new 2,4-disubstituted pyrimidine derivatives were synthesized around the original hit, but their PLK1 inhibitory activity was very poor. However the novel compounds showed nanomolar CDK9 inhibitory activity and very good antiproliferative effect on multiple myeloma cell lines (RPMI-8226).