天麻大型细胞消化蜜环菌过程中溶酶体小泡的作用

蜜环菌(Armillaria mellea Fr.)菌丝由天麻(Gastrodia elata Bl.)皮层细胞经纹孔侵入大型细胞。初期大型细胞的原生质膜凹陷,同时细胞壁产生乳突状加厚阻止菌丝侵入。当菌丝侵入大型细胞以后,凹陷的质膜将菌丝紧密包围,大量由单位膜围成的小泡聚集在其周围。随后这些小泡的膜与质膜融合并将其内含物释放到菌丝周围的空间中,凹陷质膜逐渐膨大成为一个包围菌丝的消化泡。小泡和消化泡中均具酸性磷酸酶活性反应产物,证实其分别相当于植物溶酶体系统中的初级和次级溶酶体。菌丝在消化泡中被彻底消化。     

Hyphal structure in Fusarium oxysporum (Schlecht) revealed by freeze-etching

Summary Freeze-etched hyphae of F. oxysporum exhibited a single layered cell wall; a plasmalemma, in which invaginations were frequently associated with paramural vesicles; cytoplasma bearing lipid droplets, vacuoles, intravacuolar vesicles and nuclei with typical nuclear pores. Some hyphae bore crystalline inclusions characterized by a pronounced hexagonal, external ornamentation and it is suggested that the presence of these crystals and intravacuolar vesicles are indicative of aging hyphae.     

A Cytochenfical Study of Acid Phosphatas in the Mycorrhizal Cells of Gastrodia elata Seedling

A cytochemical study has been made to examine the activity of acid β-glycerophosphatase in the mycorrhizal cells of the seedling of Gastrodia elata BI. using thin sectioning technique in which sections were embedded in glycol mathacrylate (GMA). After the seedling was invaded by the hyphae of Mycena osmundicola Lange, two different kinds of infected cells were formed in its root cortex.the outer 1–2 cell layers namely the hyphae-containing cells (or host cells) contained many coiled hyphae pelotons; the inner comparativly large cell layer or fungus-digesting cells contained a few straight hyphae. Localization of acid phosphatase in hyphae-containing cells showed that only a few senescent hyphae retained the enzyme activity and the plant cells did not release hydrolytic enzyme. So it is considered that the hyphal lysis in hyphae-containing cell may be due to autolysis. In contrast, higher acid phosphatase activity was visualized in many vesicles and small vacuoles of the fungus-digesting cells. When a hypha entered a fungus-digesting cell through a hyphae-containing cell, a number of enzyme granules (i. e, enzymecontaining vesicles) gathered around it. Later on the enzyme granules expanded gradually and became small enzyme vacuoles of 1.6–2.0 μm in diameter. Still later the small enzyme vacuoles fused with each other to form a large vacuole in which a part of an invading hypha was enclosed and gradually digested by hydrolytic enzymes. Finally,the digesting vacuole changed into a residual body containing some metabolic waste. The above results suggest that fungus-digesting cells can actively release hydrolytic enzymes by lysosomal vesicles to digest the invading hyphae, but such function is not present in the hyphae-containing cells,the role of which may be attributed to attracting and controling the invading hyphae.     

Fine structure of the host-fungus interface in orchid mycorrhiza

Summary Electron microscopy of protocorms of Dactylorhiza purpurella infected with a symbiotic Rhizoctonia sp. showed that the intracellular hyphae examined did not penetrate the plasmalemma of the host cell. Walls of hyphae within cells bore many hemispherical protuberances over which the host plasmalemma was closely pressed. we estimate that these protuberances would increase the area of contact between hyphae and host plasmalemma by about 15%. They were not found on hyphae growing on agar. Except for these protuberances, and some vesicles or tubules which invaginated the fungus plasmalemma, no other structures were seen which could be suggested to be adaptations to transport across the living fungus-host interface.     

Scanning electron microscopy of the Alnus crispa var. mollis Fern. root nodule endophyte

Nitrogen-fixing root nodules of the Alnus crispa var. mollis Fern. were studied by scanning electron microscopy (SEM). The critical point drying of glutaraldehyde-osmium fixed nodular tissue permitted an excellent morphological preservation of the three-dimensional structures of the host and endophyte cells. The nodule endophyte was observed as two forms: the hypha which can be branched, and the vesicle which developed at the parental hypha tip. The actinomycetal endophyte penetrated through the host cortical cell wall and became enveloped by a membrane. This enclosing membrane is suggested to be the invaginated host plasmalemma. Perforations of the cell wall of the host infected cell were observed. These perforations are suggested to be the result of an enzymatic degradation process, probably regulated by the penetrating endophyte hyphae. In addition to the polymorphic endophyte, endogenous bacterial contaminants were observed in the nodular tissue. The present SEM study confirms previous light microscopy and transmission electron microscopy studies of the same species of root nodule symbiosis.     

慈菇匍匐茎中分泌道的初步研究

慈茹匍蔔茎的分泌道是裂生的胞间道,分布于匍匐茎的基本组织中。单个分泌道原始细胞起始于离茎端约1毫米处的基本分生组织中,原始细胞经分裂形成5—7个上皮细胞包围着中央的裂生腔隙,成为管道系统。上皮细胞无鞘细胞包围。上皮细胞中高尔基体和内质网发达,并溢出小囊泡向着分泌道腔隙面壁的质膜附近迁移,乳汁中亦存在大量完整的小囊泡。上皮细胞和外围薄壁细胞之间的壁层具有大量胞间连丝,小囊泡和内质网的膜结构与胞间连丝末端相接,同时可见上皮细胞的质膜在数处反折内陷,形成袋状结构,在与上皮细胞相对的薄壁细胞内也有同样现象出现,袋状结构内含小形颗粒或囊泡,并在结构上显示出上皮细胞与相邻薄壁细胞间存在着活跃的物质交流。由此认为。代谢物质以整体小囊泡的形式经胞间连丝或内陷的质膜向分泌道迁移是物质运输和分泌的可能方式之一。在电镜下观察,液泡中的积聚物与乳汁十分相似,液泡可能是乳汁的贮存场所之一。     

薄荷头状腺毛分泌过程的超微结构研究

电镜观察表明,刚形成的薄荷头状腺毛的头部细胞,细胞核较大细胞质浓,有一些小液泡,质体和线粒体最显著,分泌前期,内质网及高尔基体数量明显     

Occurrence of Coated Vesicles and Alterations in Plasmalemma in Tomato Leaf Cells Infected by Phytophthora infestans Mont. (de Bary) After Treatment with Fosetyl-Al

Treatment of tomato ( Lycopersicum esculentum Mill. cv. Bonny Best) leaves with the systemic fungicide Fosetyl-Al (Tris-o-ethyl phosphonate aluminium) induced the formation of haustorial encasements or cell wall deposits in the leaf cells infected by Phytophthora infestans Mont (de Bary). Numerous coated vesicles and extremely invaginated, saclike plasmalemma were found in close spatial association with wall deposits in haustorium infected cells. Wall deposits in non-infected cells bordering degenerated, infected, cells were also accompanied by the presence of coated vesicles. In leaf tissues without treatment with Fosetyl-Al, no substantial change in the plasmalemma of infected cells was observed and coated vesicles were found only in close contact with large, smooth-surfaced vesicles. No coated vesicles were found associated with wall deposits in non-infected, neighbouring cells. The results are discussed in connection with possible functions of both coated vesicles and plasmalemma.     

种衣剂17号包衣对小麦条锈菌发育影响的超微结构研究

本研究采用电镜技术研究了种衣剂17号对小麦条锈菌发育的影响。观察结果表明,该种衣剂引起病菌和寄主细胞内发生了一系列变化。病菌菌丝和吸器内脂肪粒和液泡明显增加;菌丝壁和吸器壁呈不规则加厚;菌丝分枝处无隔膜产生或隔膜畸形;有的吸器母细胞产生的畸形入侵栓,大都不能穿透寄主细胞壁,初生吸器外间质内沉积有染色较深的物质,次生吸器可产生多个不规则分枝,但不能扩张膨大;菌丝外渗的物质可能引起寄主细胞的坏死;大多数受侵寄主细胞可分泌形成较大的胼胝质,有时寄主细胞分泌的物质可将吸器体完全包围起来。上述结果表明,种衣剂17号不仅可直接作用于条锈菌,而且也可通过影响寄主而间接地影响病菌。     

Study on Ultrastructure and Localization of Acid Phosphatase of Gastrodia elata Cortical Cells in Their Digestive Process of Armillaria mellea

In order to study the mechanism of the digestive process of Armillaria mellea in Castrodia data, electron microscopy and cytochemical method for determination of acid phosphatase activity was employed. The provacuoles were formed by means of expanded or convoluted ER under the stimulation of cortical cells and large cells of Gastrodia data by Armillaria mellea. A product of acid phosphatase (lead phosphate deposits) occured on the tonoplast. The papillae were produced in the cell wall of cortex in Gastrodia data when Armillaria mellea penetrated into its cortex. Our results showed that the enzyme was not released from cell of Armillaria mellea. A number of small vacuoles in the cortical cells disappeared. At the same time, lead phosphate deposits on the Armillaria mellea hyphae wall were observed and than Armillaria mellea hyphae wall was going to be digested, and the hyphae lost their structure. The activity of Armillaria mellea hyphae was not observed in the large cell of Gastrodia data. A great deal of small vacuoles and mitochondria were produced, at the same time the renewable nuclei and nuclolar vacuoles etc. appeared in the large cells of Gastrodia data under the stimulation of Armillaria mellea.     

彩绒革盖菌超微结构的研究

利用电子显微镜对彩绒革盖菌[Coriolus versicolor(L.:Fr.)Quél.],俗名云芝的人工培养的菌丝和野生的子实体进行超微结构的研究。结果表明:子实体由三种类型的菌丝(生殖菌丝、骨架菌丝、联络菌丝)组成。菌丝和子实体菌丝的细胞壁由两层结构组成。担子和担孢子的细胞壁由多层结构组成,至少有三层。菌丝顶端细胞的细胞质中有顶泡复合体(AVC)和顶体。菌丝细胞和子实体菌丝细胞都有桶状隔膜,在细胞质中有丰富的糖原贮存。担孢子与担子的小梗连接处出现初生壁溶化现象。     

The development and ultrastructure of gum ducts inCitrus plants formed as a result of brown-rot gummosis

Summary Young stems ofCitrus plants were infected with the fungusPhytophthora citrophthora. The effect of the infection on gum duct development was studied. The following sequence of structural changes was observed in the cambial zone: 1. The middle lamellae between layers of xylem mother cells dissolve forming duct cavities. 2. The cells around the duct cavities differentiate into epithelial cells rich in cytoplasm. 3. The amount of Golgi bodies and associated vesicles increases. The vesicles and small vacuoles, some of which seem to originate from the fusion of Golgi vesicles, contain fibrillar material that stains for polysaccharides. Vesicles and vacuoles appear to fuse with the plasmalemma. Material staining positively for polysaccharides accumulates between the plasmalemma and cell wall, and penetrates the latter. 4. The protoplast shrinks and the space below the cell wall, which contains polysaccharides, increases in volume. 5. After a period of 10 days or more the gum ducts become embedded in the xylem, and the activity of the epithelial cells ceases. The cell walls of many of them break, and the gum still present in the cells is released.     

Fine structure of vegetative mycelium and spores of Nocardia spp

The fine structure of a fragmenting and sporulating mycelium of cultures of actinomycetes possessing biochemical properties characteristic of the genus Nocardia--a cell wall of type IV and lipid LCN a--was studied. It was found that fragmenting hyphae are similar in structure to the vegetative hyphae of known actinomycetes. Sporulation takes place through the simultaneous division of a sporulating hypha by numerous septa. Spores differ from vegetative cells in the presence of a thickened electron-dense cell wall, dense internal contents, and the presence of vacuoles.     

The fine structure and histochemistry of the caecal epithelium of Calicotyle kröyeri (Monogenea: Monopisthocotylea)

The caecal epithelium of Calicotyle kröyeri consists of a single cell type which functions in the uptake and intracellular digestion of host epidermis and associated mucus. Each cell is columnar with a small basal nucleus and prominent nucleolus. Perinuclear cytoplasm contains narrow profiles of GER and mitochondria with numerous cristae. Golgi complexes are small and indistinct. Most of the cell is filled with vacuoles of heterogeneous content, the largest occupying the cell apex. There is in each cell an apical endocytotic complex comprising cell surface lamellae, apical vesicles and numerous tubular invaginations of the plasmalemma. The limiting membrane of all these components is structurally modified and bears a highly organized array of peg-like structures on its luminal surface. The complex is capable of ingesting particulate food material from the gut lumen for transfer, via vesicles, to the vacuoles for digestion. Most of the vacuoles represent the digestive elements of the cell and, histochemically, are reactive for protein, mucus and carboxylic esterases. Indigestible residues and lipid droplets accumulate in the large apical vacuole and are periodically released to the lumen by exocytosis. Small, undifferentiated caecal cells were occasionally observed in the epithelium, but their development has not been recorded.     

Endoplasmic reticulum as the initiator of bud formation in yeast (S. cerevisiae)

Summary An electron microscopical investigation of synchronously dividing yeast cells (S. cerevisiae) prepared by freeze-etching revealed that ER is inducing bud formation. In the first step, ER elements join and form a nearly-closed bag-like envelope which surrounds the nucleus and vacuoles. From the small opening of the ER-envelope, vesicles are produced by a splitting or proliferation of the ER-membranes. The vesicles fuse with the plasmalemma and release their content into the cell wall. In this limited area, bud formation starts explosively by a local evagination of the cell wall. The ER-derived vesicles are concluded to contain proteindisulfide-reductase. The limited introduction of the enzyme into the cell wall explains bud formation to be initiated by a local increase of wall plasticity caused by the reduction of disulfide bonds between cell wall proteins. The wall is forced to extrude by the internal pressure (turgor) of the cell.     

Invaginated apical vacuoles in the cells of the proximal convoluted tubule in the rat kidney

Summary Following perfusion fixation of the rat kidney with glutaraldehyde the proximal tubule cells display small apical vacuoles, large apical vacuoles, and apical vacuoles in which a part of the limiting membrane is invaginated into the vacuole. These invaginated apical vacuoles occur more frequently in proximal convoluted tubules than in proximal straight tubules. One tubular cell may contain apical vacuoles of different sizes and stages of invagination, ranging from larger vacuoles with a wide lumen and a small area of invaginated membrane to smaller elements with no apparent lumen and a large area of invaginated membrane. Invaginated apical vacuoles lie either singly in the cytoplasm or close to the membranes of other apical vacuoles, but never in contact with the cell membrane or the membranes of lysosomes, endoplasmic reticulum, Golgi apparatus, mitochondria and peroxisomes.These findings suggest that the invaginated apical vacuoles are not fixation artifacts, but rather develop in living state in cells of the proximal tubule from spherical endocytotic elements.Supported by the Deutsche Forschungsgemeinschaft (SFB 105)     

Ultrastructure of Fomes igniarius mycelium

The mycelium is composed of thin-walled hyphae, fiber hyphae and cuticular cells, the modified cells developing from the thin-walled hyphae with a dolipore septum at the differentiation point. The cell wall is usually triplelayered. occasionally, multilayered. Cell organelles such as endoplasmic reticulum, mitochondria and vesicles are found in abundance in thin-walled hyphae. Characteristic features of this fungus are the concentric membrane systems from which vesicles arise, the membrane-enclosed osmophilic bodies in vacuoles and the dense bodies in the cytoplasm. As the fiber hyphae and cuticular cells develop, the innermost layer of the wall thickens and the cell contents become disorganized so that, at the maturity of these cells, there is a reduced amount of diffuse cytoplasm, or none in the lumen.The study formed part of a doctoral dissertation submitted by the author to the University of Alberta, Edmonton, Alberta, Canada, 1971.     

Fine Structure of Germinating Botrytis fabae Sardina Conidia

The fine structure of germinating Botrytis fabae conidia wasstudied using both chemically stained sections and freeze-etchedreplicas. Germinating conidia have fewer organelles than restingconidia, glycogen is absent, and prevacuoles have disappeared.Endoplasmic reticulum which occurs as small strands close tothe cell wall of resting conidia becomes, on germination, multiplesheets surrounding the nuclei. A cross wall is formed at thebase of the germ tube soon after germination commences. Thenew wall material which appears to be continuous with this septalwall is produced, at least partly, from a new wall layer laiddown in the centre of the old conidial wall. An apical corpuscleis present at the apex of young germ tubes. Freeze-etched preparationsshow the formation of lomasomes by the passage of vesicles throughthe plasmalemma of conidia and germ tubes. In young hyphae lomasomescontain a complex arrangement of branching tubules. Some ofthe particles on the outer plasmalemma of young hyphae are arrangedin a geometrical pattern.     

Electron microscopy of vesicular-arbuscular mycorrhizae of yellow poplar. II. Intracellular hyphae and vesicles.

Intracellular hyphae and vesicles in mycorrhizal roots of yellow poplar were examined by electron microscopy. An investing layer of host wall material and cytoplasm enclosed the endophyte within the cells. Young developing hyphae contained abundant cytoplasm and few vacuoles. As hyphae matured, they became highly vacuolated and accumulated carbohydrate (glycogen) and lipid reserves. Mature vesicles were engorged with lipid droplets, possessed a trilaminate wall and were also enclosed by host wall material and cytoplasm. Compared with uninfected cells, infected cortical cells showed an increase in cytoplasmic volume, enlarged nuclei, and a reduction of starch reserves. Host nuclei were always proximal to the hyphae during hyphal development and deterioration. While other cytoplasmic components of infected and uninfected cells were comparable large electron-dense bodies occurred in vacuoles of most cells containing hyphae. Deterioration of intracellular hyphae occurred throughout the samples examined. Septa separated functional and degenerating portions of the hyphae. Hyphal deterioration involved degeneration and ultimate disappearance of fungal cytoplasm as well as collapse of hyphal walls. Based on these observations, the authors hypothesize that deterioration of the endophyte may release significant quantities of mineral nutrients, via hyphal contents, which are absorbed by the host.     

Three-dimensional reconstruction of the feeding process of the malaria parasite

The use of serial sectioning followed by three-dimensional (3D) reconstruction is a convenient way to study the spatial morphology of any structure (organ, cell, organelle). This method was applied to the study of the feeding mechanism of some strains of murine and human Plasmodium and enabled clarification of morphological features of this process. The feeding and digestive system of Plasmodium is polymorphic: in single sections, it shows rounded or elongated vesicles or vacuoles of very different sizes and content. The 3D reconstruction allowed us to describe the phenomenon both in space and in time. The contents of the host cell are taken up through the cytostome to form a sausage-shaped cytostomal tube. Individual digestive vesicles are either pinched off from the terminal portion of the tube or by the individualization of the different portions of the tube itself. The cytosomal system can be made of several tubes or vesicles always originating from cytostomes that can disappear when the tube is fully developed. A second feeding mechanism is also observed. Smaller vesicles are formed from the cytostomal vacuoles or tubes, or from the surface of the so-called "food vacuole, " or from the whole erythrocyte/parasite interface. Very few differences appear when the different strains are compared. In the chloroquine-resistant strain of P. berghei or in the P. falciparum FCR3 strain, there appears to be a large increase in the number of cytostomal vesicles, with several functional cytostomes in P. falciparum. The chronology of the appearance of the two systems is comparable between the different species except in P. falciparum, where the pigment vesicles fuse together very rapidly to form a large residual vacuole with which the subsequently formed and degraded digestive vacuoles fuse.