蒜鳞片休眠进程中胞间联络的变化及类外连丝结构与功能的研究

利用电子显微镜术,对蒜休眠进程中鳞片薄壁细胞间胞间联络的特征进行了实验观察,发现不同时期胞间联络具有随细胞间生理关系密切程度而呈现相应结构变化的特点。并观察到萌芽期鳞片中衰败细胞与存活细胞之间有类外连丝型胞间连丝的存在;以激光共聚焦荧光显微镜结合荧光标记物示踪检测,发现不透膜荧光物质分子量为457Da 的萤黄(Lucifer yellow,LYCH),可以共质体运输方式进入存活细胞内,论证了类外连丝这一胞间连丝特定修饰态的存在,并可在一段时间内继续保持生理活性,起到进行物质共质运输的功能。     

植物细胞的外连丝与类外连丝的结构与功能

外连丝作为特化的通道结构存在于植物的表皮细胞外侧壁中,而在植物局部组织衰败过程中衰亡细胞与存活细胞分界壁上有类似外连丝的半胞间连丝存在,可称之为类外连丝。本对外连丝和类外连丝的结构、功能方面的研究结果与近年进展予以综述,并讨论了植物细胞胞壁上类外连丝的出现在共质运输和细胞内含物再分配中的可能意义。     

蒜鳞片薄壁细胞衰败过程中类外连丝的形成及其共质传输能力的调节（简报）

在植物生长发育过程中,由于局部组织（细胞）的衰退或脱落．存活细胞与衰亡（或脱落）细胞分界壁上的胞间连丝衍变为类外连丝结构。这已先后在小麦胚胎发育、幼胚分化、蒜鳞茎休眠进程中以及玉米根冠组织中得到了论证。前文已曾报道．在玉米根冠细胞生长脱落进程中,脱落细胞与相邻细胞间胞间连丝有被拉伸、断裂形成类外连丝的结构变化．并经药理学试验表明。肌动蛋白和肌球蛋白共同参与了类外连丝通透性的调节。     

玉米根冠中类外连丝的结构特征及其共质传输功能(简报)

胞间连丝是植物体内连接两个相邻细胞原生质体的共质运输通道,在胞间物质的转运和通讯联络上发挥重要作用。胞间连丝的功能在生理上主要体现在它对胞间转运物质的通透性（permeability）,通透性的变化和调节影响到许多生理过程的进展与协调。在植物的不同组织及其发育的不同阶段,不同的物化因素,不同的逆境胁迫以及病原物的侵染均可导致胞间连丝的通透性呈现相应的变动。胞间连丝存在形式的多样性以及对其不同程度和不同方式的修饰,均可对胞间连丝的生理功能及其通透性有明显的影响。[第一段]     

胞外和胞内菌胞外囊泡的功能及应用

细胞外囊泡(Extracellular Vesicles,EVs)是从细胞膜上脱落或者分泌的双层膜结构的囊泡状小体.真核生物、细菌、古细菌和支原体等具有细胞结构的生物均能够释放EVs.细菌分泌的EVs含有DNA、RNA及蛋白质等多种成分,其在细菌毒力保持、免疫逃逸、细菌间物质运输、宿主细胞免疫调节、宿主转录基因调节、耐...     

蒜鳞片薄壁细胞衰退过程中酶的细胞化学定位及DNA生化分析

蒜在储藏过程中。鳞茎薄壁细胞衰退。其营养物质供给幼芽萌发生长。采用细胞化学方法,对蒜休眠进程中的鳞茎薄壁细胞进行了ATPase以及APase的细胞化学定位,结果显示在薄壁细胞的质膜、细胞壁和胞间连丝上的酶活性随着蒜自休眠至萌发的不同发育进程而呈现增强的趋势,且在萌芽期酶活性表现最为强烈。表明细胞内物质的降解、转化与输出的加强有助于细胞内含物向新生芽的彻底转移。配合采用琼脂糖凝胶电泳对衰退薄壁细胞的DNA进行了分析,实验结果表现出典型的DNA Ladder．为蒜鳞茎薄壁细胞的衰退属于受基因控制的程序性死亡范畴补充了生化证据。     

根瘤菌胞外多糖的结构与信号功能

共生固氮菌如根瘤菌属(Ｒｈｉｚｏｂｉｕｍ)、中华根瘤菌属(Ｓｉｎｏｒｈｉｚｏｂｉｕｍ)等,能在豆科作物的根部形成独特的根瘤结构,并在根瘤内将氮气固定为氨供宿主利用。根瘤菌与宿主植物的共生体系的形成是有种属特异性的,也就是说一种根瘤菌只能侵染为数不多的几种植物。根瘤形成因子(ｎｏｄｆａｃｔｏｒ,ＮＦ)对这种特异性起了重要的决定作用。ＮＦ是在植物类黄酮的诱导下由根瘤菌合成的一种脂酰基甲壳寡糖,不同根瘤菌的ＮＦ在结构上是不同的。除ＮＦ之外,根瘤菌胞外多糖(ｅｘｏｐｏｌｙｓａｃｃｈａｒｉｄｅｓ,ＥＰＳ)是对宿主植物特…     

综述: 人体体液中细胞外microRNA的起源、功能及潜在诊疗价值

最近大量的研究表明micro RNAs(miRNAs)是一类重要的调控因子．曾经被认为是非常不稳定的RNA分子——miRNA,却可以稳定存在于血液和其他体液中．更加重要的是,细胞外miRNAs被发现和多种疾病密切相关,它们可以作为诸如肿瘤等各种疾病的非侵入性生物标志物．然而,目前关于细胞外miRNA的来源以及生物学功能还不甚清楚．本文将总结最近细胞外miRNA的研究进展,并将重点介绍细胞外miRNA在疾病诊断及治疗中的作用．     

鸡腿蘑胞外多糖的形貌结构及分子量动态变化与抗氧化的相关性研究

对鸡腿蘑多糖的结构进行检测,并在此基础上探讨结构与活性的关系,对深度发掘鸡腿蘑多糖的功效具有重要意义.制备发酵时间为72 h、96 h和120 h的鸡腿蘑胞外粗多糖,采用PMP柱前衍生化-HPLC法分析其单糖组成,结果表明发酵72 h、96 h和120 h胞外多糖均由D-甘露糖、L-鼠李糖、D-葡萄糖、D-半乳糖、D-...     

黄素介导的胞外电子转移研究与工程改造*

产电微生物的胞外电子转移在能源、环境等诸多领域有着非常重要的应用价值。希瓦氏菌(Shewanella oneidensis)作为模式产电微生物,其电催化系统引起了广泛的研究。黄素作为S. oneidensis重要的电子载体,其介导的胞外电子转移是电子传递过程中的一个限速步骤。然而自然环境中野生型S. oneidensis的黄素分泌量极低,对其工程改造也存在一定的局限性,因而严重阻碍了胞外电子的传递过程,这已成为限制其电子转移的主要瓶颈。基于S. oneidensis黄素介导的电子转移机制,系统地从黄素的合成路径及转录调控的角度阐明了黄素合成的调控因素,并综述近年来利用代谢工程、合成生物学以及电极材料修饰等方法来提高黄素介导电子转移的工程化策略,未来可利用一些系统的研究方法和表达工具来加速产电微生物黄素介导的胞外电子转移。     

The preimplantation mammalian embryo: characterization of intercellular junctions and their appearance during development.

Junctions in developing mammalian embryos were investigated with lanthanum tracer and freeze-fracture methods. The outermost blastomeres of mouse morulae possess focal tight junctions which become zonular and exclude lanthanum, thereby separating the “inner” cells from the maternal environment. This compartmentalization, creating a microenvironment inside the embryo, may be required for cell determination and for the accumulation of fluid during blastocoel expansion. Desmosomes appear for the first time at the blastocyst stage in the trophoblast junctional complex which also is characterized by gap junctions and a zonula occludens with underlying microfilament-like material and microtubules. Both gap and tight junctions have been visualized in freeze-fracture replicas of rabbit blastocysts. The zonula occludens forms a permeability barrier which is consistent with the high transtrophoblast electrical resistance. Mouse presumptive and mature inner cell mass (ICM) cells were associated by frequent gap junctions whereas junctional complexes were absent. Trophoblast gap and adhering junctions and cytoplasmic processes appeared to fix the ICM to one pole of the embryo and partially isolate it from the blastocoel. These findings support the idea that the ICM and trophoblast communicate upon implantation and require that the intercellular junctions between them be dissembled if the ICM is to migrate to a mesometrial position.     

Conditions controlling the development of distant intercellular interactions during ultraviolet radiation]

The study is concerned with ascertaining the role of UV radiation in distant intercellular interactions (DII) and the conditions resulting in "MIRROR" CYTOPATHIC EFFECT ("M" CPE). It has been found that the UV radiation-induced extreme state of the cells in a radiant culture produces distantly in an intact detector culture, which has only an optic contact with it, the cytopathic effect (CPE) as a repercussion of a specificity of morphological manifestations imprinted in the affected culture. UV preparadiation of the detector cells aids in manifestation of the "mirror" CPE.     

A change in the puff spectrum during development of Drosophila virilis]

The puff spectrum has been studied in the salivary gland chromosomes of D. virilis from 48 hrs of the 3rd larval until the gland lysis. 142 puffs were observed in the D. virilis genome. Among them, 43% were observed at all developmental stages and other puffs were unstable: 47.1% appear at a certain stage and degrade or remain until the gland lysis; 9.9% are characterized by the "pulse" activity, i.e. they appear at a certain stage, degrade and reappear. The number of newly appeared puffs exceeds that of fully degraded ones, i.e. the number of puffs during the gland development until its lysis increases constantly. At the stage of puparium formation, sexual differences in the puff length were found: puffs were longer in males than in females.     

Effect of different soil and clove treatments in the control of white rot of garlic

Soil solarisation was consistently efficacious in reducing inoculum density to undetectable levels in a field naturally‐infested with Sclerotium cepivorum. This treatment delayed epidemic onset of white rot of garlic 2–3 months as compared with the untreated control or the inoculation of planting furrows with Glomus intraradices. Furthermore, significant reductions of disease incidence and of the standardised AUDPC were also observed in solarised plots, resulting in quantitative and qualitative yield improvement. Similar effects were observed in plots planted with tebuconazole‐treated cloves, confirming previous results, whereas Trichoderma harzianum was ineffective as a biocontrol agent, when applied to planting furrows. The inoculation of plots with G. intraradices before planting, in three consecutive years, was neither effective for disease control nor on the development of garlic, although the root systems of garlic plants from all the experimental treatments were heavily mycorrhizal at harvest, indicating the presence of native arbuscular mycorrhizal propagules in the soil and their survival after soil solarisation.     

Alliin lyase localization in bundle sheaths of the garlic clove (Allium sativum)

The enzyme alliin lyase (E.C. 4.4.1.4) catalyzes formation of allicin, the parent of several sulfur-containing compounds responsible for flavor, odor, and pharmacological properties of garlic (Allium sativum). Alliin lyase is a major product of the storage bud (clove), accounting for 10% of its total protein. Accumulation of this protein was characterized by locating alliin lyase deposits within the clove. Paraffin sections stained for general protein using aniline blue-black reveal dense deposits within parenchymatous bundle sheaths. Deposits are most pronounced around phloem. Remaining storage parenchyma, not in contact with bundles, appears structurally uniform, with some protein accumulating in cells near the outer surface of the clove. In freehand sections of unfixed cloves, bundle sheath cells are the only ones to show green autofluorescence when excited by blue light. Such fluorescence is consistent with the presence of pyridoxal phosphate cofactor of alliin lyase. An alliin lyase activity stain, based on detecting aminocrotonate-generating enzymes, shows activity to be restricted to bundle sheath cells in fresh material. Finally, enrichment of alliin lyase in bundle sheaths is shown by immunocytochemical staining of these areas using a polyclonal antibody generated against purified enzyme. Aliin lyase concentrates in bundle sheaths, while little if any occurs in storage mesophyll not in contact with vascular bundles. Deposits in the cloves may reflect the enzyme's role in protecting underground storage buds from decay and predation. Positioning near the phloem suggests that alliin lyase, or compounds related to its metabolism, may be translocated to and from the clove during development.     

Sea urchin hyalin: appearance and function in development

Embryonic chicken sensory cells from dorsal root ganglia and a clonal line of pheochromocytoma cells (PC-12) extended neuronal-like processes within 24 hr of seeding on a naturally produced, basement membrane-like extracellular matrix (ECM) in the absence of nerve growth factor (NGF). Plating on ECM also induced a rapid cell attachment and flattening of these cells and supported the survival of embryonic sensory cells in primary cultures. Unlike the effect of NGF on PC-12 cells, the ECM-induced morphological differentiation was transient and led to disintegration and degeneration of processes bearing PC-12 cells. The ECM-induced morphological differentiation was not inhibited by anti-NGF antibodies, and the cells retained their ability to bind and internalize NGF in a manner similar to that observed on plastic. PC-12 cell attachment and flattening occurred on dishes coated with collagen type IV in a way similar to that observed on ECM, but precoating the dishes with fibronectin had no effect. Extension of cell processes was not induced by either substrate. Morphological differentiation but not the induction of cell adhesion and flattening was inhibited by either prefixation with glutaraldehyde, oxidation with periodate, or preexposure to concanavalin A of the ECM, suggesting that the ECM and in particular its sugar moieties play an active role in the induction of neurite outgrowth. It is suggested that close contact with the ECM provides chemical or mechanical cues that permit contactmediated elongation and directed growth of both embryonic and regenerating nerve fibers.