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1.
Prof. Dr. Taisuke Nakao 《Cell and tissue research》1976,166(2):241-254
Summary Myotendinous junctions in the myotomal tail muscles of the tadpole of Rana rugosa were examined by electron microscopy. At the site of the myotendinous junction, the sarcolemma is covered on its sarcoplasmic aspect by the connecting filament layer and the attachment layer, and on the extracellular aspect by the intermediary layer and the external lamina, with associated collagen fibrils. The intermediary layer consists of filamentous structures which closely resemble microfibrils (Hanak and Böck, 1971), spine-like or thread-like profiles (Korneliussen, 1973) and intermediary layer (Nakao, 1975a, b) in the myotendinous junctions of other vertebrate skeletal muscles.Particularly interesting is the fact that all the coverings and linings of the sarcolemma, including the external lamina, are completely absent in the terminal segment of the finger-like sarcolemmal invagination characteristic of the myotendinous junction. Furthermore, special types of coupling between a sac of sarcoplasmic reticulum and a part of the sarcolemmal invagination are frequently observed. These couplings always occur along the region of the sarcolemma where the external lamina is absent. The couplings show features similar to those of the triad, such as SR feet , scalloped SR membranes and granular content of the SR sac, suggesting that they are analogous and functionally similar to the triad and other equivalent structures. 相似文献
2.
Aeromonas salmonicida variants were characterized for alterations in their cell surface structure and used to examine reconstitution of the surface protein layer (A-layer). Variants lacking outer membrane O-polysaccharide were devoid of A-layer and excreted stainable floret-like material of the surface protein (A-protein). One variant, showing partial loss of O-polysaccharide, was associated with a disrupted A-layer and excretion of some A-protein. Variants lacking A-protein but possessing O-polysaccharide rapidly absorbed and concentrated sufficient excreted A-protein at the cell surface to coat the cells with a single confluent layer. Although differences in electrophoretic mobilities of A-proteins and O-polysaccharides from typical and atypical strains were evident, the different A-proteins and A-protein-deficient variants were interchangeable for reconstitution of a surface protein layer. No association of A-protein with cell surfaces of unrelated gram-negative bacteria was observed.Abbreviations A-layer
additional surface protein layer
- A-protein
surface protein
- Ast
Aeromonas salmonicida typical
- Asa
Aeromonas salmonicida atypical
- A-
phenotypically A-protein-negative variant
- O-
phenotypically O-polysaccharide-negative variant
- Owk
phenotypically O-polysaccharide weak variant
- BHI
brain heart infusion
- SDS-PAGE
sodium dodecylsulfate-polyacrylamide gel electrophoresis
- TEM
transmission electron microscopy 相似文献
3.
Summary The ultrastructure of the heterocyst and its development from the vegetative cell is described. The ultrastructure of the akinete is also described. The mature heterocyst (still attached to the filament) has an elaborate structure which is distinct from both that of the normal vegetative cell and the akinete (the normal reproductive cell).Despite the extra structural detail seen in the electron micrographs, the observations do not indicate a likely physiological role for the heterocyst. However, since the developing-mature heterocyst has an organised structure, it is probable that it has an active metabolism. In contrast, the detached heterocyst has a highly disorganised structure and, for this reason, it is likely to be metabolically inactive and incapable of germination. 相似文献
4.
Summary The breakdown and disappearance of particles was followed by electron microscopy on synchronously germinating populations of B. emersonii zoospores. The sequence of morphological changes, unaffected by the method used to induce germination, was divided into four stages. Initially, the particle's surrounding unit membrane becomes amorphous and buds off vesicles that fuse with the plasma membrane. Simultaneously, ca. 80 m vesicles are visible either partially embedded in, or lying free along, the inner surface of the electron dense matrix. These small vesicles seem to originate from a newly detected membrane system in the electron dense matrix. In the next stage, particles characteristically adhere to various organelles, especially the nuclear cap. In subsequent stages the particles continue to decay by releasing 80 m vesicles from their matrices and by budding off vesicles from their surrounding membranes. Often, multivesicular bodies are formed when the 80 m vesicles become enclosed by the particle's budding outer membrane. In the final stage, the surrounding membranes of the different particles fuse and produce large vacuoles containing many of the electron dense matrices which, though by now partially fragmented, continue to release 80 m vesicles. The relationship of the above events to the formation of the cell wall is discussed. 相似文献
5.
The predacious watermold Zoophagus insidians traps loricate rotifers on short, lateral branches of the main, hyphal axis. These branches or traps are packed at their distal ends with a number of vesicles filled with an electron-dense matrix. Electron micrographs of the mycelium disclose a two-layered wall; the outer layer is electron dense and the inner, electron transparent. The outer dense layer on the tip of the trap is organized into a number of fine ridges and occasional discontinuities. Thin sections through recently trapped rotifers indicate that the cilia of the animals are stuck to the trap by a glue. This adhesive is derived from secretion of the matrix of the vesicles aggregated in the tip of the trap. The secretion mechanism is triggered by the animal and is accompanied by: 1. The separation of the two layers of the wall, 2. fusion of the vesicles with the cell membrane and 3. extrusion of the glue through pits in the tip of the inner wall of the trap. After snaring a rotifer, the previously arrested branch grows as a haustorium into the body cavity of the animal. The host tissues disintegrate within a few hours and appear to be the main nutrient source of the fungus. 相似文献
6.
M. D. H. M. William A. Mujeeb-Kazi 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1992,84(5-6):528-534
Summary
Psathyrostachys juncea (synonymous to Elymus junceus; 2n=2x=14, NN) has unique biotic and abiotic attributes that could contribute towards wheat improvement. The effectiveness of such an intergeneric hybridization program depends greatly on being able to establish diagnostic markers of the alien chromosomes. Isoelectric focusing (IEF) analyses of six enzyme systems have identified five biochemical markers — malate dehydrogenase (MDH), esterase (EST), shikimate dehydrogenase (SKDH), phosphoglucomutase (PGM), and -amylase (-AMY) — to be of positive diagnostic value; glucosephosphate isomerase (GPI) banding profiles were of no definite value in the background of Triticum aestivum cvs Chinese Spring and Seri-82, the potential recipients of Ps. juncea chromosomes. The Giemsa C-banding karyotype distinctively separates the Ps. Juncea chromosomes from each other and from those of T. aestivum with little banding site polymorphisms prevalent among its accessions analyzed, indicating the usefulness of C-bands as cytological markers. 相似文献
7.
Ultrastructure and early development of the pore plate sensilla ofGymnomerus laevipes (Shuckard) (Vespoidea,Eumenidae) 总被引:1,自引:0,他引:1
Summary The oval pore plates (approx. 17 m long) are separated from the antennal cuticle by a furrow, the inner wall of which is flexible. The thin perforated plates are strengthened by an encircling and a middle ledge, the latter of which branches into about 100 almost parallel rims. Each pore plate is innervated by about 20 sense cells. The dendrites fork into numerous branches occupying the outer receptor lymph cavity below the perforated plate. Each pore plate is associated with one thecogen cell, two trichogen cells, one tormogen cell and one envelope cell 4. A so-called additional cell surrounds the sensillum in the imaginal stage. The envelope cells in the later of the two pupal stages examined, have reached an arrangement which immediately precedes the secretion of the cuticulin layer. The surface of the duplicate trichogen cells is almost equal in area to the completed perforated plate. A dendritic sheath, entirely reduced in the imago, protrudes into the exuvial space, where it encloses a single dendrite.In the younger pupal stage the Sensillenanlage forms a crater, whereby envelope cell 4 overtops the other envelope cells. The distal ends of the trichogen cells are divided into several appendages that form the bottom of the crater. 相似文献
8.
Summary Cell-wall-softening enzymes affect the plasticity of the tip wall of pollen tubes and modity tube elongation. Length of pear pollen tubes is increased by the addition of -1,3-glucanase at the beginning of in-vitro germination. The longer tubes after 3 hours are primarily the result of earlier germination. Application of -1,4-glucanase or pectinase to germinating pollen does not affect germination but enhances the growth rate of 1-hour-old pollen tubes. The stimulating effects of -1,4-glucanase and pectinase are additive. Denatured enzymes had no effect. Proteinase, pectin esterase, acid phosphatase and -amylase only inhibited growth and germination. Replacing the medium 1 hour after germination begins stops pollen-tube growth; growth can be restored by adding cellulase-pectinase mixtures to the replacement medium. These results provide evidence that cellulase and pectinase are important in pollen-wall extension, and that callose-hydrolyzing enzymes are involved in pollen germination but not wall extension.A contribution of the Florida Agricultural Experiment Station, Journal Series No. 3069. 相似文献
9.
V. K. Lackney R. M. Spanswick T. J. Hirasuna M. L. Shuler 《Plant Cell, Tissue and Organ Culture》1990,23(2):107-114
Cultured grape cells accumulate anthocyanins in vacuoles rather than secreting them into the nutrient medium. Therefore, grape cells that contain tonoplast segments in their plasmalemma should be capable of excreting anthocyanins rather than sequestering them in their vacuoles. In initial attempts to construct such novel cells, small vacuoles were fused with the plasmalemma of cultured plant cells. Protoplasts were isolated from grape calluses that produce and accumulate anthocyanins. Small vacuoles were formed by gently rupturing vacuoles isolated from grape protoplasts. Although small vacuoles and protoplasts became aligned in an AC field, the tonoplast and plasmalemma did not readily fuse when subjected to 3 DC pulses of 1200 V cm–1 for 50 s each. Changes in the intensity, number and/or duration of the DC pulses had no effect on the fusion process. When 1.0% polyethylene glycol was added to the electrofusion buffer, however, small vacuoles and protoplasts fused within a few minutes after the DC pulses were applied. These novel grape cells remained viable for several hours.Abbreviations BSA
bovine serum albumin
- 2,4-D
2,4-dichloro-phenoxyacetic acid
- DTT
dithiothreitol
- EGTA
ethyleneglycol-bis-(-amino-ethyl ether)-N,N,N,N
- MES
2-[N-Morpholino]ethanesulfonic acid
- MOPS
3-[N-Morpholino]propanesulfonic acid
- PVP
polyvinylpyrrolidone 相似文献
10.
Morphology of freeze-etchedTreponema refringens (Nichols) 总被引:4,自引:0,他引:4
The freeze-etch technique was used to study the morphology ofTreponema refringens (Nichols). There is a single band of cytoplasmic fibrils which follows a path in the form of a right-handed helix with a periodicity of 1500 nm around the body of the treponeme just below the cytoplasmic membrane. There are two major fracture planes, one located in the interior of the outer envelope and the second in the interior of the cytoplasmic membrane. The blebs or surface protuberances, which are quite prominent in negativestained preparations, were not evident with freeze-etch preparation, indicating they are not a part of the normal structure of this organism. The outer envelope in untreated cells was observed to closely fit the body of the treponeme, whereas the outer envelope of glutaraldehyde-treated cells had a loose, wrinkled appearance. Thus the loose-fitting outer envelope generally described for treponemes is most likely an artifact of preparation for negative-staining and thinsectioning. 相似文献
11.
Summary In the present study, synaptic ribbons were studied morphologically and quantitatively in hamster pineal gland. The number of ribbons and spherules of hamster pinealocytes was counted over a 24-h period. The 24-h variations in the quantity of synaptic ribbons were found to parallel fluctuations in pineal melatonin concentrations. No significant circadian changes were observed for synaptic spherules, indicating different roles for these two structures. 相似文献
12.
H. G. Sangeetha A. R. Reddy 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1988,76(3):381-384
Summary The etched (et) mutation in maize causes distinct depressions and structural gaps in the endosperm and also gives rise to virescent seedlings, - and -Amylase activities were observed to be higher in et
+
et
+ kernels and seedlings as compared to that of the et et mutant. The total amylase and -amylase trends during germination also differed between normal and mutant kernels and seedlings (it increases in the wildtype and decreases in et et). On the contrary, the overall -amylase trend was found to be similar in both genotypes (slight decrease during germination). The native gel electrophoresis of crude enzyme extracts did not reveal any qualitative differences in and amylases during germination. The germinating et et kernels initially showed lower levels of starch compared with the wild type kernels, whereas no such difference was found at later stages of germination. It is concluded that et gene associated endosperm lesions lead to an impairment of starch degradation in germinating kernels resulting in virescent seedlings. 相似文献
13.
Zusammenfassung Im Ovar von Chironomus sind in Phase 1 des 4. Larvenstadiums polygonal abgeflachte Innenzellen von kleineren Außenzellen umgeben, die Bakteroide und Phagosomen enthalten; zwischen den Innenzellen liegen unregelmäßige Zelltrümmer (keimbahnbegleitende Substanzen). Zu Beginn der Ovariolenbildung werden in Phase 3 durch Spalträume zwei Schichten der Außenzellen voneinander getrennt, von denen die innere (Follikel- und Eikanalepithel) regelmäßige Buchten bildet. In diese Buchten wandern von innen Zellpaare ein, die an synaptischen Komplexen bzw. multiplen Chromatinstrukturen als Ei- und Nährzellen kenntlich sind. Zwischen beiden Zellen sind Fusome häufig, die später in eigentümlicher Weise geschlossen werden. Zwischen den Eikanalzellen entsteht in Phase 5 durch Spaltbildung der Eikanal; in Phase 7 sind die Eikanalzellen auffallend glykogenreich. Kurz vor der Vitellogenese treten im Bereich der Oocyte Membransysteme und annulated lamellae auf; akzessorische Kerne werden als Ausstülpungen des Oocytenkernes gebildet und später abgeschnürt. In Phase 9 sind an der Peripherie der Eizelle Mikrovillisäume und Pinocytosebläschen sichtbar. Die distalen Zellen der Ovariole haben Eioder Nährzellcharakter, sind aber bei Ch. melanotus nicht von Follikelzellen umgeben und werden beim weiteren Ovariolenwachstum reduziert. Trotz extrem geringer Nährzellzahl der Follikel scheint das Chironomus-Ovar funktionell nicht von anderen polytroph meroistischen Insektenovarien unterschieden.
Ultrastructure of Chironomus (Dipt.) gonads1. Normal development of ovaries during the fourth larval instar
Summary In the ovary of Chironomus during phase 1 of the fourth larval instar, polygonally flattened inner cells are surrounded by smaller outer cells which contain bacteroids and phagosomes. Irregular cell remnants (germ line accompanying substances) lie among the inner cells. At the beginning of ovariole formation in phase 3, two layers of outer cells are separated by the formation of fissures. The inner layer of these cells (follicle- and egg-passage epithelium) forms regular invaginations. Cell pairs, identified as oocytes and nurse cells by synaptic complexes or multiple chromatin structures, wander from inside into the invaginations. Frequently between the two cells are fusomes, which later close in a characteristic manner. During phase 5, an egg passage is formed as a fissure among the egg-passage cells. During phase 7, the egg passage cells are conspicuously full of glycogen. Shortly before vitellogenesis membrane systems and annulated lamellae appear in the region of the oocyte. Accessory nuclei are formed by a tieing-off of projections of the the oocyte nucleus. During phase 9, microvilli and pinocytotic vesicles can be seen at the periphery of the oocyte. The distal cells of the ovariole are of oocyte or nurse cell nature, but in Ch. melanotus they are not surrounded by follicle cells and are reduced during further ovariole growth. In spite of the extremely small number of nurse cells in the follicle, the Chironomus ovary apparently does not differ functionally from other polytrophic meroistic insect ovaries.
Mit Unterstützung durch die Deutsche Forschungsgemeinschaft. 相似文献
14.
Summary We have investigated the associations between -tubulin and mitochondria in freshly isolated cardiac myocytes from the rat. Beta-tubulin was identified by using monoclonal antibodies for immunofluorescence and high resolution immunogold electron microscopy. In addition, conventional transmission and scanning electron microscopic studies were performed. After chemical stabilization in a formaldehyde solution, the myocytes were shock-frozen at –150°C, cryosectioned at –70°C and subsequently processed for immunohistochemical and immunocytochemical microscopy. A characteristic of the rod shaped myocytes is the presence of a dense network of microtubules in the cytoplasm displaying a pattern of strong anti--tubulin reaction. The complexity of this network however varies considerably among the myocytes reflecting microtubule dynamic instability. Further, our findings demonstrate that the -tubulin label in rod cells is confined to the perinuclear and interfibrillar spaces and, therefore, is largely colocalized with the cytoplasmic organelles. In myocytes undergoing severe contracture the distribution of -tubulin is entirely restricted to the outer mitochondrial-containing domain. This implies that, in a cell model with marked segregation of the contractile filaments and organelles, mitochondria are codistributed with microtubules in the total absence of desmin intermediate filaments. Moreover, our immunogold preparations demonstrate anti--tubulin labelling in the outer mitochondrial membrane as well as of fibres in close apposition to this membrane. These results indicate the presence of a specific -tubulin binding to the outer mitochondrial membrane that probably also involves microtubule based translocators and/or MAPs. 相似文献
15.
Galactomannan was localized by scanning and transmission electron microscopy on the cells and cell walls of Schizosaccharomyces pombe. The markers were prepared from colloidal gold granules labelled with an -galactopyranosyl-binding lectin isolated from the seeds of Bandeiraea simplicifolia. Part or all of this -galactomannan was present in the outer layer of the cell wall and was uniformly distributed even on the fission scars.Non-Standard Abbreviations Au
lectin-labelled colloid
- SEM
scanning electron microscopy
- TEM
transmission electron microscopy 相似文献
16.
G. Bentzen J. M. Piret E. Daher A. L. Demain 《Applied microbiology and biotechnology》1990,32(6):708-710
Summary Certain Bacillus brevis strains produce gramicidin S (GS) during sporulation, and germination of such spores is delayed at the stage of outgrowth by endogenous or exogenous GS. Claims have been made that the transition from germinating spores into vegetative cells is dependent on GS destruction. We observed no such destruction of either exogenous or endogenous GS. Thus, in our hands, the recovery of the inhibited germinating spores must be dependent on something other than GS elimination.Offprint requests to: G. Bentzen 相似文献
17.
In man, deficiency of ADA activity is associated with an autosomal recessive form of severe combined immunodeficiency (SCID), a disease with profound defects of both cellular and humoral immunity. Current treatments of ADA deficient patients include bone marrow transplantation, enzyme replancement and somatic gene therapy. The mechanism of the selective immune cell pathogenesis in ADA-SCIDS is, however, still poorly understood. Thus, the generation of an ADA deficient mouse model will be of considerable benefit to understand better the pathophysiology of the disorder and to improve the gene therapy treatments.We have disrupted the adenosime deaminase (ADA) gene in embryonic stem cells using a new efficient promoter trap gene-targeting approach. To this end, a dicistronic targeting construct containing a promoterless IRES geo cassette was used. This cassette allows, via the internal ribosomal entry site (IRES), the direct cap-independent translation of the geo reporter gene which encodes a protein with both -galactosidase and neomycin activities. After indentification of targeted clones by Southern blot, successful inactivation of the ADA gene was first confirmed by producing, from our heterozygote clones, an homozygote cell line. This line shows no ADA activity as judged by zymogram analysis. Second, we have been able to detect in the targeted clones, a specific galactosidase activity using a sensitive fluorogenic assay. The targeted ES cell clones are currently being injected into blastocysts to create an ADA deficient mouse model. 相似文献
18.
The ultrastructural changes produced by iodine-potassium iodide solution on yeast cells of Sporothrix schenckii were investigated by transmission electron microscopy in order to clarify the mechanism of oral potassium iodide therapy for sporotrichosis. Yeast cells were dipped with solutions containing various concentrations of iodine. The rate of germination decreased markedly between the range of iodine concentrations from 0.63 g/ml to 5.0 g/ml. No significant ultrastructural changes were seen at the concentration of the iodine of 1.25 g/ml (80% germination) or less. In the concentration of 2.5 g/ml (50% germination), normal cells and degenerated cells coexisted. When the cells were treated with 5.0 g of iodine per ml (0% germination) or more, their interior structures were completely destroyed. It is assumed that iodine treatment of the organism causes rapid destruction in the whole cell. 相似文献
19.
Summary Anhydrobiotic and active hydrated specimens of the tardigradeMacrobiotus hufelandi were investigated by electron microscopy, and the cellular fine structure of both stages was compared. Besides conventional preparation methods, totally anhydrous techniques were used to avoid hydration artefacts in the anhydrobiotic specimens. In the latter the cytoplasm was very electron dense and masked many cell constituents, however, membraneous structures, nuclei, mitochondria, microtubules, and myofilaments could be resolved in the micrographs. After substraction of all peculiarities caused by the preparation methods within the micrographs of cells from anhydrobiotic specimens, the comparison revealed that the basic morphology of the cells and their organelles is not changed in the anhydrobiotic specimens. Maintenance of the structural integrity of its cells is a basic ability of this organism to survive desiccation.This report is part of a doctoral dissertation submitted by the author to the Fakultät für Naturwissenschaften of the University of Heidelberg in 1976. The author would like to thank Prof. Dr. E.Schnepf who guided the dissertation. I would like to thank too the Studienstiftung des deutschen Volkes for general support by a Promotionsstipendium. 相似文献
20.
Summary The effect of a non-indole compound, phenylacetic acid (PAA), on the induction of somatic embryogenesis in tissue cultures of geranium (Pelargonium x hortorum Bailey cv. Scarlet Orbit Improved) was investigated. Hypocotyl explants derived from young, dark-grown seedlings were cultured on Murashige and Skoog (1962) medium (MS) supplemented with PAA or IAA (0.01–120 M) alone or in combination with BAP (8 M). Somatic embryogenesis was induced by both PAA and IAA at 0.01–20 M with 8 M BAP, however, the optima differed considerably for the two compounds. Maximal activity of IAA for somatic embryogenesis was found at 0.1–2.5 M, whereas PAA gave best results at 10 and 20 M under identical culture conditions. Higher concentrations (30–120 M) of IAA or PAA in the medium induced callusing in the explants, but the callus was neither embryogenic nor morphogenic.Abbreviations BAP
N6-benzylaminopurine
- IAA
indole-3-acetic acid
- MS
Murashige and Skoog (1962)
- PAA
phenylacetic acid 相似文献