ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
Filter
  • Microtubules  (38)
  • Springer  (38)
  • Cell Press
  • Nature Publishing Group
  • Oxford University Press
  • 2005-2009
  • 1980-1984  (38)
  • 1925-1929
  • 1982  (15)
  • 1980  (23)
  • 1925
Sammlung
Schlagwörter
Verlag/Herausgeber
  • Springer  (38)
  • Cell Press
  • Nature Publishing Group
  • Oxford University Press
Erscheinungszeitraum
  • 2005-2009
  • 1980-1984  (38)
  • 1925-1929
Jahr
  • 1
    Digitale Medien
    Digitale Medien
    Tubulin evolution: Two major types of α-tubulin (1982)
    Springer
    Journal of molecular evolution 19 (1982), S. 80-86 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Microtubules ; Tubulin ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Tubulin subunits have been isolated from a variety of protists and marine invertebrates. The sources were: sperm tails of a tunicate (Ciona intestinalis), an abalone (Haliotis rufescens) and a sea anemone (Tealia crassicornis), the gill cilia of a clam (Mercenaria mercenaria), the cilia of a ciliate (Tetrahymena pyriformis) and the cytoplasm of a slime mold (Physarum polycephalum). All the β-tubulins, as characterised by their electropherograms after limited proteolytic cleavage withStaphylococcus aureus protease, were fairly similar. In contrast, two markedly different peptide patterns were found for the α-tubulins of (a) metazoan axonemes and (b) protistan axonemes, plant axonemes and slime mold cytoplasm. Metazoan axonemal α-tubulin peptide patterns could be further divided into two similar but distinct subtypes which did not correlate with the taxonomic divisions of deuterostomia and protostomia, or to different tubulins within an axoneme, or to different tubulins of flagella and cilia. We have postulated that these small differences may be accounted for by a simple glutamicaspartic acid exchange at a particular position in the α-tubulin sequence. Identical peptide patterns were observed for sea urchin and sea anemone sperm tail tubulins, proving that the metazoan type of axonemal tubulin arose before the divergence of bilateral and radial symmetric organisms. The close similarity of the slime mold cytoplasmic α-tubulin peptide pattern to protistan and plant axonemal α-tubulin patterns suggests that the same type of tubulin might be used to form both axonemal and cytoplasmic types of microtubules in protists and plants. The large structural constraints imposed upon this tubulin molecule probably allowed very little change in its primary structure, thus explaining the similarity of tubulins from organisms which diverged at such an early time in eukaryote history. Duplication and modification of the tubulin gene may then have led to the development of specific axonemal and cytoplasmic microtubules during the evolution of the metazoa.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02100226
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 2
    Digitale Medien
    Digitale Medien
    Migration and division of cleavage nuclei in the gall midge,Wachtliella persicariae (1980)
    Springer
    Development genes and evolution 188 (1980), S. 65-73 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Nuclear migration ; Cleavage ; Microtubules ; Ultrastructure ; Gall midge
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary In the eggs ofWachtliella persicariae the cleavage nuclei move relative to the surrounding ooplasm. This ‘active’ migration is caused by an organelle whose ultrastructure was studied throughout the mitotic cycle. It consists of a greatly enlarged polar cytaster derived from the mitotic apparatus, linked to the nucleus by 100 Å filaments. The microtubules of the cytaster were found only during periods of active nuclear migration, i.e., from the onset of anaphase to the early prophase of the next mitotic cycle. They are always solitary and follow the course of the astral rays, which are known to temporarily adhere to peripheral structures of the egg cell and to exert tractive forces. In contrast to the cytaster microtubules, the microtubules in the spindle are bundled and persist from early metaphase through late telophase. During ontogenesis the first migration cytaster is built up between 3 and 12 min after oviposition near the anterior egg pole, in the vicinity of the sperm nucleus. In non-inseminated eggs time lapse films show a migration cytaster to develop autonomously in a region free from nuclei, but it does not follow the normal path of the male pronucleus. In several cases the female pronucleus, which remains without a cytaster of its own, was observed to move to the cytaster generated in the absence of the male pronucleus. Whether or not it is adhering to a nucleus, the cytaster divides into two at the correct time, i.e, corresponding to the first cleavage division in fertilized eggs. In some non-inseminated eggs this type of ‘pseudocleavage’ has been observed to occur repeatedly, giving rise to an increasing number of anucleate cytasters.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00848611
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 3
    Digitale Medien
    Digitale Medien
    Reorganization of cortical microtubules and cellulose deposition during leaf formation in Graptopetalum paraguayense (1980)
    Springer
    Planta 149 (1980), S. 181-195 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Cell walls ; Cellulose ; Graptopetalum ; Microtubules
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In the “regeneration” of a shoot from a leaf of the succulent, Graptopetalum paraguayense E. Walther the first new organs are leaf primordia. The original arrangement of cellulose microfibrils and of microtubules (MTs) in the epidermis of the leaf-forming site is one of parallel, straight lines. In the new primordium both structures still have a congruent arrangement but it is roughly in the form of concentric circles that surround the new cylindrical organ. The regions which undergo the greatest shift in orientation (90°) were studied in detail. Departures from the original cellulose alignment are detected in changes in the polarized-light image. Departures from the original cortical MT arrangement are detected using electron microscopy. The over-all reorganization of the MT pattern is followed by the tally of MT profiles, the various regions being studied in two perpendicular planes of section. This corrects for the difference in efficiency in counting transverse versus longitudinal profiles of MTs. Reorientation takes place sporadically, cell by cell, for both the cellulose microfibrils and the MTs, indicating a coordinated reorientation of the two structures. That MTs and cellulose microfibrils reorient jointly in individual cells was shown by reconstruction of the arrays of cortical MTs in paradermal sections of individual cells whose recent change in the orientation of cellulose deposition had been detected with polarized light. Closeness of the two alignments was also indicated by images where the MT and microfibril alignments co-varied within a single cell. The change-over in alignment of the MTs appears to involve stages where arrays of contrasting orientation co-exist to give a criss-cross image. During this critical reorganization, the frequency of the MTs is high. It falls during subsequent enlargement of the organ. It was found that the rearrangement of the cortical MTs to approximate a series of concentric circles on the residual meristem occurred before the emergence of leaf primordia. Through their apparent influence on microfibril alignments, the changes in MT disposition, described here, have the potential to generate major biophysical changes that accompany organogenesis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00380881
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 4
    Digitale Medien
    Digitale Medien
    Anti-microtubular herbicides and fungicides affect Ca2+ transport in plant mitochondria (1980)
    Springer
    Planta 149 (1980), S. 336-340 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Ca2+ transport ; Fungicides ; Herbicides ; Microtubules ; Mitochondria
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The herbicides amiprophosmethyl (APM) trifluralin, and oryzalin as well as the fungicides methylbenzimidazolyl carbamate (MBC), O-isopropyl N-phenyl carbamate (IPC), and chlorisopropyl N-phenyl carbamate (CIPC), which are known to cause the destruction of microtubules in vivo but do not interfere with tubulin polymerization in vitro, have been examined with respect to their ability to affect Ca2+ transport in isolated cell organelles. In contrast to colchicine which has no effect on Ca2+ transport in isolated mitochondrial and microsomal fractions, all of the substances investigated caused considerable reduction of ca2+ net uptake into mitochondrial but not into microsomal fractions. This reduction has been shown to be due to an increase in passive Ca2+ efflux. These results have been extrapolated to in vivo situations where they are postulated to act by raising cytoplasmic Ca2+ levels.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00571167
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 5
    Digitale Medien
    Digitale Medien
    Extraction and immunochemical assays of a tubulin-like factor in cotton seedlings (1982)
    Springer
    Planta 154 (1982), S. 402-406 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Gossypium ; Microtubules ; Tubulin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Antibodies to tubulin were prepared in rabbits by immunization with reduced-carboxymethylated calf-brain tubulin. In immunodiffusion tests the antibodies showed full cross reactivity with the immunogen as well as with native calf-brain tubulin. The same antibodies showed cross reactivity with a factor in extract of cotton (Gossypium hirsutum L.) cotyledons but there was no full immunological identity between calf-brain tubulin and this factor. A solid-phase radioimmunoassay for quantitative estimation of this plant tubulin-like factor was developed. It measured the binding of antibodies to immobilized calf-native tubulin. Competition between the unknown soluble tubulin-like factor, and immobilized tubulin was assayed at serum dilution of 1:50. Extraction conditions which preserved the antigenic properties of the tubulin-like factor from cotton cotyledons were defined. The radioimmunoassay measured quantities of the tubulin-like factor in the range of 0.1–10 μg-equivalents of calf-brain tubulin. Immediately after homogenization of the tissue only 25% of the total amount of tubulin-like activity was present in soluble form, while most of it remained in the insoluble fraction. Apparent maximal solubilization was achieved spontaneously 10 h after homogenization or by treatment with guanidine hydrochloride. These results indicate that in this material, tubulin is not released immediately by homogenization but remains assembled in microtubules and-or in a bound or sequestered form.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01267806
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 6
    Digitale Medien
    Digitale Medien
    Polarity and growth of caulonema tip cells of the moss Funaria hygrometrica (1980)
    Springer
    Planta 147 (1980), S. 405-413 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Caulonema ; Cell growth (tip) ; Funaria ; Microtubules ; Organelle modification ; Polarity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In the caulonema tip cells of Funaria hygrometrica, chloroplasts, mitochondria, and dictyosomes have differences in structure which are determined by cell polarity. In contrast to the slowly growing chloronema tip cells the apical cell of the caulonema contains a tip body. Colchicine stops tip growth; it causes the formation of subapical cell protrusions, redistribution of the plastids, and a loss of their polar differentiation. Cytochalasin B inhibits growth and affects the position of cell organelles. After treatment with ionophore A23 187, growth is slower and shorter and wider cells are formed. D2O causes a transient reversion of organelle distribution but premitotic nuclei are not dislocated. In some tip cells the reversion of polarity persists; they continue to grow with a new tip at their base. During centrifugation, colchicine has only a slight influence on the stability of organelle anchorage. The former polar organization of most cells is restored within a few hours after centrifugation, and the cells resume normal growth. In premitotic cells the nucleus and other organelles cannot be retransported, they often continue to grow with reversed polarity. Colchicine retards the redistribution of organelles generally and increases the number of cells that form a basal outgrowth. The interrelationship between the peripheral cytoplasm and the nucleus and the role of microtubules in maintaining and reestablishing cell polarity are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00380180
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 7
    Digitale Medien
    Digitale Medien
    Microtubules and coated vesicles in guard-cell protoplasts ofAllium cepa L. (1980)
    Springer
    Planta 149 (1980), S. 389-401 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Allium ; Cell wall Coated vesicles ; Guard cells ; Microtubules ; Protoplasts
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Protoplasts were prepared from the guard cells ofA. cepa. Epidermal peels taken from expanding green leaves and largely free of mesophyll were treated with Cellulysin, and protoplasts were harvested after 18 h of digestion. That the protoplasts were derived from guard cells was ascertained from their characteristic vacuolar autofluorescence and from observations showing that all other epidermal cells are killed in the peeling procedure. The protoplasts proved to be a good system with which to view the cell cortex and inner surface of the plasmalemma. The lysis of cells adhering to polylysine-treated, Formvar-coated grids, followed by negative staining in uranyl acetate, showed that many microtubules normally present in ordered arrays in situ remain closely applied to the inner surface of the plasmalemma in protoplasts. In addition, numerous vesiculate elements including coated vesicles and/or pits are present amongst the microtubules. Similar vesicles are evident in thin sections of fixed, embedded guard cells and protoplasts. The significance of these structures in the cell cortex is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00571175
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 8
    Digitale Medien
    Digitale Medien
    Microtubules, protoplasts and plant cell shape (1980)
    Springer
    Planta 147 (1980), S. 500-506 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Cell shape ; Colchicine ; Daucus ; Immunofluorescence ; Microtubules ; Protoplasts
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Indirect immunofluorescence has been used to study the function of cytoplasmic microtubules in controlling the shape of elongated carrot cells in culture. Using a purified wall-degrading preparation, the elongated cells are converted to spherical protoplasts and the transverse hoops of bundled microtubules are disorganised but not depolymerised in the process. Since microtubules remain attached to fragments of protoplast membrane adhering to coverslips and are still seen to be organised laterally in bundles, it would appear that re-orientation of the transverse bundles is due to loss of cell wall and not to the cleavage of microtubule bridges. After 24 h treatment in 10-3 M colchicine, microtubules are depolymerised in elongated cells but, at this time, the cells retain their elongated shape. This suggests that wall which was organised in the presence of transverse microtubule bundles can retain asymmetric shape for short periods in the absence of those tubules. However, after longer periods of time the cells become spherical in colchicine. Neither wall nor tubules therefore exert individual control on continued cellular elongation and so we emphasize the fundamental nature of wall/microtubule interactions in shape control. It is concluded that the observations are best explained by a model in which hooped bundles of microtubules—which are directly or indirectly associated with molecules involved with cellulose biosynthesis at the cell surface—act as an essential template or scaffolding for the orientated deposition of cellulose.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00380194
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 9
    Digitale Medien
    Digitale Medien
    Topographical features of the membrane of Poterioochromonas malhamensis after colchicine and osmotic treatment (1980)
    Springer
    Planta 148 (1980), S. 84-88 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Colchicine ; Membrane structure ; Microtubules ; Osmotic treatment ; Plasmalemma ; Poterioochromonas
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Changes in membrane topography in the flagellate Poterioochromonas malhamensis, as a result of colchicine and osmotic-stress treatments, have been studied using freeze-fracturing and thin sectioning. Ridges, but not rows of intramembrane particles, in the PF-face which denote the position of underlying cortical microtubules, together with the ridge associated with their point of origin (flagellar root fibre 1), dissappear after colchicine or short-term (5 min) osmotic treatments. Cortical microtubules are destroyed as a result of the former, but not the latter treatment. Longer periods in osmoticum allow a recovery of the microtubule — associated membrane ridges. Despite careful isosmotic fixations distinct cross-bridges between microtubules and the plasmalemma were not discernible in thin section.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00385446
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 10
    Digitale Medien
    Digitale Medien
    Effect of microtubule-disrupting drugs on protein and RNA synthesis in Physarum polycephalum amoebae (1980)
    Springer
    Archives of microbiology 128 (1980), S. 34-40 
    Details
    ISSN: 1432-072X
    Schlagwort(e): Protein ; RNA synthesis ; Microtubules ; Microfilament-disrupting drugs ; Heat ; Cold shock ; Recovery
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The effects of the microtubule-disrupting drugs, colchicine, vinblastine, podophyllotoxin, griseofulvin, and lumicolchicine (10-5 M), on protein and RNA synthesis were studied in Physarum polycephalum amoebae in culture. All, except lumicolchicine, were found to simultaneously reduce the rate of protein synthesis and stimulate RNA synthesis. These results parallel the effects seen in cells exposed to heat shock. Treatment of the cells with a microfilament-disrupting drug, cytochalasin B (10 μg/ml in ethanol), resulted in a reduced rate of protein synthesis after 2 h compared to a similar effect by vinblastine in 5–15 min. A morphological abnormality, microtubule paracystals, were seen associated with centrioles in vinblastine-treated cells in which protein synthesis had been reduced by 50%. Vinblastine and podophyllotoxin were shown to interfere with the recovery of protein synthesis after inhibition by low or elevated temperatures. The possible role of microtubules in regulating the translational response of a cell to an external environmental stimulus is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00422302
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 11
    Digitale Medien
    Digitale Medien
    Microtubular proteins and tubulin pool changes during zoospore germination in the fungus Blastocladiella emersonii (1982)
    Springer
    Archives of microbiology 131 (1982), S. 323-329 
    Details
    ISSN: 1432-072X
    Schlagwort(e): Blastocladiella ; Microtubules ; Tubulin ; Pools ; Zoospore ; Germination ; Flagella ; Retraction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The tubulin proteins of Blastocladiella emersonii have been characterized, and the pool sizes of soluble tubulins measured to evaluate turnover during early development. The axonemal tubulins and soluble tubulin dimers were typical of tubulin proteins from other eukaryotes. [3H]cholchicine binding assays were used to estimate the soluble tubulin pools of zoospores and during early development. The free colchicine-binding pool of tubulin in zoospores represents 1% of the soluble protein. It increases by 49% after encystment (at 30 min), decreases to 21% below the spore level by 50 min, and then increases slowly with growth. Neither deflagellation of zoospores prior to encystment, nor inhibition of axonemal disassembly, alter the postencystment pool increases. Disassembly of cytoskeletal microtubules occurs in either circumstance, but can account for only 54% of the pool increase. It was concluded that (1) the retracted axonemal tubulins are not returned to the soluble pool detected by cholchicine binding and are probably degraded; (2) new microtubules are supplied by the preexisting cytoplasmic pool that expands from disassembly of cytoplasmic microtubules; and (3) that the tubulins of the axonemes and soluble pools may be distinct.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00411179
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 12
    Digitale Medien
    Digitale Medien
    The effects of colchicine and gibberellic acid on growth and microtubules in excised lettuce hypocotyls (1982)
    Springer
    Planta 154 (1982), S. 204-211 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Cell growth, orientation ; Colchicine ; Gibberellin and cell growth ; Hypocotyl (growth) ; Lactuca ; Microtubules
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The effect of colchicine on growth and microtubules in H2O-and gibberellic acid (GA3)-treated hypocotyls of lettuce (Lactuca sativa L. cv. Arctic) was examined. Hypocotyls of seedlings from γ-irradiated as well as non-irradiated seedlings were used in order to establish that the drug was affecting cell elongation and not cell division. Although colchicine inhibited elongation of GA3-treated hypocotyl sections at concentrations as low as 1 μM, it did not affect the growth of sections. Rather, colchicine treatment caused a reorientation of the plane of cell expansion. Lumicolchicine had no effect on elongation of hypocotyl sections at a concentration (100 μM) at which colchicine abolished GA3-induced elongation. Colchicine was only effective in reorienting the plane of growth in light; in darkness, it inhibited both radial and longitudinal cell expansion. Analogs of colchicine as well as other antimicrotubular agents were ineffective in changing the polarity of growth in lettuce. Electron microscopy showed that transversely oriented microtubules were numerous in the cortical cytoplasm adjacent to the longitudinal wall of freshly excised hypocotyl sections. Incubation in GA3 did not change the number or orientation of these microtubules, while incubation in H2O caused a reduction in their number and altered their distribution. Colchicine abolished microtubules under all conditions of incubation tested, but did not affect other characteristics of cell ultrastructure.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00387865
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 13
    Digitale Medien
    Digitale Medien
    Microtubules, dendritic spines and spine apparatuses (1980)
    Springer
    Cell & tissue research 208 (1980), S. 171-181 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Microtubules ; Dendritic spine apparatus ; Synapse ; Development ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Using techniques for enhanced microtubular preservation, including albumin pretreatment (Gray, 1975), occipital cortex of rats was studied electron microscopically at various ages of development. A close structural relationship was seen between microtubules, sacs of SER and the postsynaptic “thickening” in primordial spines and with the dense “plate” material of spine apparatuses. Stereoscopic preparations in addition show a more complicated substructure than previously described for the “plate”. Microtubules may contribute to the formation of the “plate” of the spine apparatus which in turn is associated with the postsynaptic “thickening” of the mature spine. Possible functional correlates are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00234868
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 14
    Digitale Medien
    Digitale Medien
    Effects of ethylene on the orientation of microtubules and cellulose microfibrils of pea epicotyl cells with polylamellate cell walls (1982)
    Springer
    Protoplasma 110 (1982), S. 5-14 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Cell wall ; Ethylene ; Microfibrils ; Microtubules ; Radial cell expansion
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Following a 5 hours ethylene treatment, cortical cells of Pea (Pisum sativum L. var Alaska) epicotyl third internode showed a change in the orientation of both microtubules near the plasma membrane and recently deposited cellulose microfibrils. Control cortical cells had mostly transverse microtubules. The ratio of the average frequency of transverse to longitudinal microtubules was 6.0. After 5 hours of ethylene treatment, cortical cells had mostly longitudinal microtubules, with the ratio of transverse to longitudinal microtubules equal to 0.1. Epidermal cells were more variable than cortical cells with regard to the frequency of longitudinal and transverse microtubules. Observation of cortical cell walls in conventionally stained thin sections revealed that recent deposition of microfibrils had been primarily transverse in almost all of the control cortical cells sampled. In contrast, more than half of the ethylene-treated cortical cells had recent deposition oriented primarily longitudinally. This change in microtubule and microfibril orientation may be early enough to constitute the primary effect of ethylene leading to radial cell expansion.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01314675
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 15
    Digitale Medien
    Digitale Medien
    Ultrastructure of meiosis in the mossRhynchostegium serrulatum I. Prophasic microtubules and spindle dynamics (1982)
    Springer
    Protoplasma 110 (1982), S. 23-33 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Meiosis ; Microtubules ; Polarity ; Ultrastructure ; Mosses
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary An extensive system of microtubules develops during meiotic prophase in the mossRhynchostegium serrulatum (Hedw.)Jaeg. &Sauerb. Development of the cytoskeleton can be traced to early prophase when the nucleus is acentric and the single plastid divides into four plastids. The cytoskeletal microtubules are associated with equidistant positioning of the four plastids at the distal tetrad poles and with migration of the nucleus to a central position in the sporocyte. The cytoskeleton, which interconnects plastids and encloses the nucleus, contributes to the establishment of moss sporocyte polarity. Just prior to metaphase I evidence of the prophase cytoskeleton is lost as the bipolar metaphase I spindle develops in association with discrete polar organizers located in opposite cleavage furrows between plastids.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01314678
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 16
    Digitale Medien
    Digitale Medien
    Interdependence of cell cycle events inSchizosaccharomyces pombe. Terminal phenotypes of cell division cycle mutants arrested during dna synthesis and nuclear division (1982)
    Springer
    Protoplasma 110 (1982), S. 54-62 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Cell cycle ; Microtubules ; Mitosis ; Schizosaccharomyces ; Spindle pole body
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Temperature-sensitive cell division cycle (cdc) mutants of the fission yeastSchizosaccharomyces pombe, previously characterized as defective in nuclear division were examined by thin section electron microscopy. All of the mutants failed to enter mitosis, rather they accumulated at one of four distinct terminal phenotypes. Class one were arrested with a nucleus rectangular in cross-section and a laterally situated spindle pole body (SPB). The second group had spherical or rectangular nuclei with a single SPB. The sole member of the third group wascdc 27. K 3, which had a spherical crenated nucleus with a single SPB from which microtubules emerged and extended into the cytoplasm. Allelic variants ofcdc 25 comprised the fourth group all of which displayed aberrant nuclear morphologies. Utilizing this ultrastructural data together with a knowledge of the transition points of these mutants a model for the interdependence of certain cell cycle event is proposed in which the initiation of DNA synthesis is uncoupled from the replication and separation of the SPB. This paper also provides new information on SPB structure inS. pombe. This is discussed in connection with the transient assembly of both spindle and cytoplasmic microtubules.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01314682
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 17
    Digitale Medien
    Digitale Medien
    The cytomorphic system of anucleate non-mammalian erythrocytes (1982)
    Springer
    Protoplasma 113 (1982), S. 23-32 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Anucleate cells ; Cellular morphogenesis ; Erythrocyte, non-mammalian ; Marginal band ; Microtubules ; Batrachoseps
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Cytomorphic structure was studied in erythrocytes ofBatrachoseps salamanders, a genus unique among non-mammalian vertebrates because most of the erythrocytes are anucleate. These anucleate erythrocytes are highly flattened, quite variable in size, and generally elliptical. All of them were found to contain marginal bands of microtubules (MBs), as observed in phase contrast and darkfield after Triton lysis. The MBs of larger cells typically twisted into figure-8 forms upon lysis. Whole mounts of the lysed anucleate cells consisted only of the MB plus a trans-MB network of material (TBM), as observed by electron microscopy. If lysis was carried out in the presence of 0.5 M KCl, all of the MBs circularized immediately and none were twisted. The network (TBM) was now missing, suggesting that it is needed for maintenance of MB ellipticity and plays a role in MB twisting. Small numbers of living anucleate erythrocytes were constricted in their mid-region, and others were pointed at one end. Correspondingly pointed MBs were observed after lysis, exhibiting a range of forms compatible with the mechanism proposed byEmmel (1924) in which the anucleate erythrocytes arise by amitotic division of nucleated ones. The results show that these erythrocytes retain the typical nonmammalian cytomorphic system, and are thus unlike those of adult mammals. The network component (TBM) is present even though nuclei are absent, making it unlikely that it functions simply to position the nucleus. The observations are consistent with the hypothesis that the flattened, elliptical shape of non-mammalian vertebrate erythrocytes is generated by TBM tension applied across the faces of the MB “frame”, and that excessive tension induced by lysis (without KCl) produces MB twisting.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01283036
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 18
    Digitale Medien
    Digitale Medien
    Development of protophloem in roots ofAegilops comosa var.thessalica. I. Differential divisions and pre-prophase bands of microtubules (1982)
    Springer
    Protoplasma 113 (1982), S. 110-119 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Protophloem ; Microtubules ; Pre-prophase band ; Cell division ; Root ; Aegilops
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The formative divisions of protophloem mother cells in roots of the grassAegilops comosa var.thessalica have been investigated by means of light and electron microscopy. Two successive differential divisions create protophloem poles consisting of a protophloem sieve element and two companion cells. Pre-prophase bands of microtubules appear in premitotic cells anticipating the plane of orientation of the cell plate and indicating the site where the daughter wall will join the parent one. Evidence is accumulated that the site previously occupied by pre-prophase band is bisected by the new wall. Structural asymmetries that could express polarity, like organelle displacement, were not observed in premitotic cells. A working hypothesis is proposed integrating the conclusions of the present study in a diagram correlating pre-prophase bands of microtubules and differential divisions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01281999
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 19
    Digitale Medien
    Digitale Medien
    Asexual reproduction in the suctorianDiscophrya collini (1982)
    Springer
    Protoplasma 111 (1982), S. 195-205 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Discophrya ; Evaginative budding ; Microtubules ; Reproduction ; Suctoria
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Discophrya collini reproduces asexually through the formation of a ciliated swarmer by evaginative budding. This process is initiated by the repeated replication of a single subcortical kinetosome to form a kinetosome field. The epiplasm of the multilayered cortex covering this field becomes reduced in thickness and the whole cortex invaginates to produce an internal embryonic cavity. The kinetosomes become organised into rows, and each produces a cilium which projects into the cavity. On completion of the embryonic cavity its walls are extruded through the cavity opening to form an external ciliated swarmer connected to the parent by a thin bridge of cytoplasm. It is suggested that this evagination is induced by a rapid breakdown of supporting microtubules in the cavity wall and the subsequent hydrostatic pressure exerted by the body cytoplasm. The connecting bridge shows no specialised ultrastructural features and separation of swarmer from parent probably is achieved by the active movement of the swarmer. The cytoplasm of the swarmer is similar in structure to that of the adult cell but contains a number of primordia of tentacle axonemes. The infraciliature resembles that of other suctorian swarmers. On settling, the cilia of the swarmer are lost, at least some by resorption, a stalk may be secreted and the axoneme primordia are extended to form functional tentacles.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01281967
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 20
    Digitale Medien
    Digitale Medien
    Some effects of colchicine on microtubules and cell division in roots ofAzolla pinnata (1980)
    Springer
    Protoplasma 102 (1980), S. 31-51 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Microtubules ; Morphogenesis ; Cell Walls ; Roots ; Colchicine ; Cell division
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Removal and subsequent reformation of microtubules in cells of the root-tips ofAzolla pinnata R. Br. was achieved by short pulse treatments with the drug colchicine. Loss of microtubules led to the formation of multinucleate cells more frequently than to the arrest of mitosis at metaphase, and primary and secondary wall formation was also disrupted. Recovery of root development was limited. Growth of all roots ceased 5–6 days after the pulse treatment. Following the reappearance of microtubules, renewed deposition of normal wall thickenings occurred in developing xylem elements. Multinucleate cells became subdivided by walls in the apparent absence of a phragmoplast. The plane in which the new wall was formed was often located as it would have been in an untreated root, but in a number of cases abnormal or precious positioning of new walls was observed. Clusters of microtubules, matrix material, and vesicles or particles, taken to indicate microtubule initiation, were observed during the recovery from treatment.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01276946
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 21
    Digitale Medien
    Digitale Medien
    Purification of lumicolchicine for use in studies of plant development (1980)
    Springer
    Protoplasma 103 (1980), S. 105-114 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Colchicine ; Lumicolchicine ; Microtubules ; Mitosis ; Wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Lumicolchicine was purified by preparative thin-layer chromatography. Tests for purity were ultraviolet absorption spectrophotometry, analytical thin-layer chromatography, and a bioassay using wheat roots. Wheat roots treated for 3 days with 10−3 M lumicolchicine showed no c-mitosis, but had reduced growth compared with controls.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01276669
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 22
    Digitale Medien
    Digitale Medien
    The organization of cortical microtubule arrays in the radish root hair (1980)
    Springer
    Protoplasma 103 (1980), S. 205-229 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Cell wall ; Cytochalasin B ; Microfibril orientation ; Microtubules
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Cortical microtubule arrays in the radish root hair were analyzed from reconstructions of serial ultra-thin sections in order to test extant hypotheses concerning the role of microtubules in the deposition of oriented microfibrils of cellulose. Passing away from the tip, root hairs exhibit a transition from random to oriented deposition of microfibrils at approximately 25 μm. Along the root hair, passing back from the tip, the microtubules: a) increase in number to a plateau at 25 μm; b) change their length profiles from approximately 60% less than 1 μm long in the hair tip to approximately 40% less than 1 μm long at 60 μm; c) maintain a constant pattern of angular deviation from the long axis, which is similar to the deviation pattern of the oriented wall fibrils; d) maintain a constant (approximately 70% of tubules) close (within 50 nm) proximity to the plasma membrane (PM); e) maintain a low (approximately 20%) degree of inter-microtubule proximity (i.e., within 50 nm of one another); f) show evidence for some variable long range (〉50 nm) association. Fixation with glutaraldehyde in a complete microtubule polymerization medium (MTPM), or pretreatment with cytochalasin B cause an approximate twofold increase in 1. the proportion of long microtubules in the tip region and 2. microtubules within 50 nm of one another. Fixation in incomplete MTPM (without GTP) produces results similar to phosphate buffer controls. Alternative explanations for these results are examined. A new hypothesis accounting for microtubule involvement in oriented microfibril deposition is described.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01276268
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 23
    Digitale Medien
    Digitale Medien
    Griseofulvin-induced alterations in site of dividing nuclei and structure of septa in a dikaryon ofSchizophyllum commune (1980)
    Springer
    Protoplasma 103 (1980), S. 323-331 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Dikaryon ; Griseofulvin ; Microtubules ; Nuclear division ; Septal development ; Septal dissolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Ultrastructural study of a dikaryon of the basidiomyceteSchizophyllum commune showed that treatment with griseofulvin affected the site of the dividing nuclei and the location and structure of the septa. The microtubules were considered to be the primary target of griseofulvin, since they participate in nuclear division and movement in the hyphae, and their assembly is known to be in other organisms than fungi inhibited by griseofulvin. It is pointed out that dikaryotic hyphae with two nuclei and a clamp connection per cell are more sensitive indicators of the effect of griseofulvin than homokaryotic hyphae, whose structure is less complex.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01276277
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 24
    Digitale Medien
    Digitale Medien
    Microtubules, organelle movement, and cross-wall formation at the sporangial-rhizoidal interface in the fungus,Chytridium confervae (1980)
    Springer
    Protoplasma 104 (1980), S. 201-221 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Cell wall ; Chytridiomycetes ; Chytridium confervae ; Cross-wall ; Microtubules ; Ribosomes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Chytridium confervae is a eucarpic, monocentric chytrid. We have used light and electron microscopy to study the relationship between the nutrient absorbing rhizoids and the asexually reproductive sporangium during growth. We have also examined the induction of zoosporogenesis by starvation, and subsequent differentiation until zoospore release. During growth the cytoplasm of the rhizoids and the developing sporangium was continuous and similar. At the start of starvation a bundle of fibers that were visible with light microscopy appeared at the junction between the rhizoids and the sporangium. Two hours after initiation of starvation a wall, that was also visible with light microscopy, formed to separate the rhizoids from the sporangium. Electron microscopy revealed a large, ordered array of microtubules in the thallus at the same time that the fibers appeared, and a sharp difference in the density of ribosomes in the cytoplasm of the sporangium and that of the rhizoids that was apparent immediately after starvation. This cytoplasmic difference was preserved by the formation of a cross-wall that was penetrated by plasmodesmata. After the wall was formed the cytoplasm of the rhizoids senesced. Comparison ofC. confervae with other organisms that use arrays of microtubules to move organelles is made and speculation on the role of the microtubules in organelle movement and wall formation inC. confervae is offered.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01279768
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 25
    Digitale Medien
    Digitale Medien
    Cell shape and microtubules in zoospores of the green algaChlorosarcinopsis gelatinosa (Chlorosarcinales): Effects of low temperature (1980)
    Springer
    Protoplasma 104 (1980), S. 283-293 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Cell shape ; Chlorosarcinopsis ; Low temperature ; Microtubules
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The effect of low temperature (2 °C) on cell shape and microtubules in zoospores of the green algaChlorosarcinopsis gelatinosa has been investigated. The zoospores are 4–6 times longer than wide with a mean length of 12,5 μm and can be kept in the dark for several hours without changes in cell shape. Cell shape changes have been evaluated quantitatively by measuring changes in cell length. Low temperature induces a decrease in cell length which exhibits a two-step kinetic: during the first 30 minutes a rapid rate of decrease in cell length was measured, while during the next 4 hours a slow rate of decrease in cell length was observed. Complete regeneration of zoospore length occurs when cold-treated cells are subjected to the original zoospore induction temperature (30 °C) for two hours. Observation of numbers, disposition and types of microtubules in the zoospore during decrease in cell length has shown that within 30 minutes after cold application the secondary cytoskeletal microtubules (scmt) disappear, while flagellar root microtubules are unaffected. During this period most cells develop a prominent posterior appendage (tail). Sections demonstrate the presence of several microtubules in these tails. Flagellar root microtubules probably extend into the tails and disappearance of scmt starts at the posterior pole of the cell. Regeneration of zoospores to original cell length is coupled with reappearance of scmt starting at the anterior pole of the cell. It is concluded that secondary cytoskeletal microtubules constitute the main cytoskeleton inChlorosarcinopsis zoospores and that flagellar root microtubules contribute to only a minor extent to the cytoskeleton, because they cannot retain the cell shape. The results are discussed with respect to the functional significance of flagellar root microtubules in green algae.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01279773
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 26
    Digitale Medien
    Digitale Medien
    Distribution of cortical microtubules in tobacco protoplasts. An immunofluorescence microscopic and ultrastructural study (1980)
    Springer
    Protoplasma 105 (1980), S. 27-43 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Immunofluorescence ; Microtubules ; Plant protoplasts ; Tobacco
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The arrangement of cortical microtubules in tobacco protoplasts is described using the following techniques: 1. Transmission electron microscopy (TEM) of thin sections of whole protoplasts, 2. TEM of negatively stained protoplast ghosts, and 3. Indirect immunofluorescence microscopy of protoplast ghosts. Ghosts were prepared by attaching freshly isolated protoplasts to glass coverslips or formvar/carbon-coated grids with poly-L-lysine and then bursting them either osmotically or by detergent treatment in the presence of a microtubule stabilizing buffer. Osmotic bursting of protoplasts yielded large pieces of plasma membrane with attached microtubules. These preparations proved very useful for measuring the density and length of cortical microtubules. Detergent treatment dissolved the plasma membrane and altered the distribution of cortical microtubules.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01279847
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 27
    Digitale Medien
    Digitale Medien
    Influence of the antimicrotubule agent, mebendazole, on the secretory activity of intestinal cells ofAscaridia galli (1980)
    Springer
    Protoplasma 105 (1980), S. 69-76 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Mebendazole ; Ascaridia ; Secretion ; Microtubules ; Anthelmintic
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The anthelmintic compound mebendazole caused the disappearance of microtubules in the intestinal cells ofAscaridia galli. Electron microscopy revealed that soon after the microtubules disappeared there was an accumulation of secretory vesicles near the golgi areas. subsequently many of these vesicles aggregated forming dense large vesicles near the terminal web of the intestinal cells. This provides further evidence for the involvement of microtubules in the secretion of products from eukaryotic cells. It seems likely that inhibition of microtubule directed secretory functions in various cell types is an important function in the anthelmintic activity of the benzimidazole carbamates.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01279850
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 28
    Digitale Medien
    Digitale Medien
    Reprogramming of cells following wounding in pea (Pisum sativum L.) roots. I. Cell division and differentiation of new vascular elements (1982)
    Springer
    Protoplasma 112 (1982), S. 143-151 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Cell division ; Differentiation ; Microtubules ; Preprophase bands ; Vascular elements ; Regeneration ; Transfer cells
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Normally quiescent cortical tissue of pea roots can be induced, by severing the adjacent vascular cylinder of the root, to undergo redifferentiation to form new files of tracheary and sieve elements which bridge the wound. The development of vascular transfer cells is also induced. Redifferentiation is normally accompanied by division of the original cortical cells. The planes of cell division, especially those preceding sieve element formation, are aligned very precisely in adjacent cells, to produce smooth files of cells. In roots wounded 3–4 mm from the apex, bands of microtubules in the periphery of the cells (pre-prophase bands) form at sites which correspond to the expected planes of cell division.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01284088
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 29
    Digitale Medien
    Digitale Medien
    Microtubules do not control microfibril orientation in a helicoidal cell wall (1982)
    Springer
    Protoplasma 113 (1982), S. 85-87 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Microtubules ; Microfibril orientation ; Helicoidal cell wall ; Root hair ; Equisetum hyemale
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The secondary cell wall layer of the young root hair ofEquisetum hyemale (L) has a helicoidal texture. The cortical microtubules in these hairs maintain an axial alignment while microfibrils are being deposited with a different orientation in each subsequent layer. The role of cortical microtubules in microfibril orientation is disputed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01283042
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 30
    Digitale Medien
    Digitale Medien
    Protoplasmic streaming in the giant unicellular green algaAcetabularia mediterranea (1980)
    Springer
    Protoplasma 102 (1980), S. 295-306 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Acetabularia ; Inhibitors ; Microcinematography ; Microfilaments ; Microtubules ; Protoplasmic streaming
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The sensitivity of the dual intracellular transport system inAcetabularia mediterranea (Koop andKiermayer 1979 a) to cytochalasin B (CB, 10−5 mol), chlorisopropyl-N-phenylcarbamate (CIPC, 2.10−4 mol), and amiprophosmethyl (APM, 3.10−5 mol) has been studied by microcinematography. Vegetative cells before cap formation, 2–3 cm in length, and cells with a maximum sized cap, containing secondary nuclei, were used for the experiments. All intracellular movements ceased under the influence of CB, while in contrast to “headed streaming bands” and to the migration of the secondary nuclei, the movement of chloroplasts at “thin filaments” was found to be insensitive to Col, CIPC, and APM. All inhibitory effects of the drugs on protoplasmic streaming were completely reversible within a time of less than 10–20 minutes recovery from the drugs. The results suggest an involvement of microfilaments in all intracellular movements while, in addition, microtubules seem to be connected with the movement on “headed streaming bands”, including the migration of secondary nuclei.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01279593
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 31
    Digitale Medien
    Digitale Medien
    Ultrastructural observations on changes in cell shape in chromatophores of the sea urchin Centrostephanus longispinus (1980)
    Springer
    Cell & tissue research 206 (1980), S. 21-33 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Chromatophores ; Light-sensitivity ; Alteration in cell shape ; Microtubules ; Echinoids
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Alterations in cell shape of the light-sensitive chromatophores of the sea urchin Centrostephanus longispinus were studied by scanning- and transmission electron microscopy. Transition of the aggregated to the dispersed state is accompanied by incorporation of vesicles into the membrane of the pigment cell. During dispersion a system of microtubules originating from centriole-like structures is established throughout the stellate cell. Within restricted areas of the cell, cytoplasmic differentiation and condensation is found. The possible functional significance of the findings is briefly discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00233604
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 32
    Digitale Medien
    Digitale Medien
    Inhibition of intracellular protein transport in the mouse exocrine pancreas induced by vinblastine (1980)
    Springer
    Cell & tissue research 206 (1980), S. 73-81 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Exocrine pancreas (mouse) ; Electron microscopic autoradiography ; Microtubules ; Protein transport ; Vinblastine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The effect of vinblastine on the intracellular transport of newly synthesized protein in the mouse exocrine pancreas in vivo was studied by electron microscopic autoradiography after administration of 3H-leucine. Vinblastine (1.1 μmole/mouse; i.v. injection) was in general given 1 h before radioleucine and 2–4 h before fixation of the pancreas by perfusion with glutaraldehyde. Vinblastine causes the disappearance of microtubules, mainly present in controls in the apical portion of the acinar cell. After injection of vinblastine, zymogen granules form clusters located throughout the cell but often associated with Golgi areas. The latter are enlarged mainly due to the accumulation of small vesicles. In addition, Golgi areas are displaced, most often in an apical direction. Electron microscopic autoradiography demonstrated that vinblastine delays the appearance of labeled protein in zymogen granules; even 2 h after injection of radioleucine the majority of silver grains is located over the rough endoplasmic reticulum while very few grains are related to zymogen granules. This finding might be related to the structural changes of the Golgi areas observed. Although intracellular migration of protein is retarded, zymogen granules are formed. However, many of the labeled granules are found in peculiar locations, often distant from the acinar lumen. The present study suggests that vinblastine, possibly due to its effect on microtubules, influences both the formation and the translocation of zymogen granules.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00233609
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 33
    Digitale Medien
    Digitale Medien
    Role of microtubules in milk secretion — Action of colchicine on microtubules and exocytosis of secretory vesicles in rat mammary epithelial cells (1980)
    Springer
    Cell & tissue research 207 (1980), S. 361-376 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Microtubules ; Colchicine ; Secretory vesicles ; Milk secretion
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Effect of colchicine on microtubules was studied in mammary epithelial cells treated both in vivo and in vitro with the alkaloid. Three hours after the intramammary infusion of colchicine, secretory activity of mammary epithelia ceased, milk constituents accumulated and were randomly distributed within the cytoplasm, sometimes leaking into the perialveolar connective tissue, and autophagic vacuoles were prevalent. It appeared that an accelerated involutionary process was occurring. No microtubules were observed after this treatment. In vitro treated cells appeared to be less affected by the alkaloid. Although numerous casein-containing secretory vesicles accumulated in the cytoplasm, lipid droplet accumulation was less, and fewer autophagic vacuoles were observed, although lysosomes were commonly observed. Occasionally, obliquely sectioned microtubules were found in cells treated with low concentrations of colchicine but were absent at higher colchicine concentrations; however, paracrystalline inclusions (tubulin aggregates) were observed in some cells at all concentrations of the drug. These observations provide evidence that drugs which interfere with microtubule integrity reduce the secretory activity in mammary epithelia. This evidence is consistent with the concept of an association of the microtubular system and the secretory process.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00224613
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 34
    Digitale Medien
    Digitale Medien
    Cold and metabolic inhibitor effects on cytoplasmic microtubules and the Golgi complex in cultured rat epiphyseal chondrocytes (1980)
    Springer
    Cell & tissue research 210 (1980), S. 403-415 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Chondrocytes ; Golgi complex ; Microtubules ; Colchicine ; Metabolic inhibitors
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Previous work has shown that exposure of cultured chondrocytes to colchicine leads to disappearance of microtubules and dispersion of the dictyosomes of the Golgi complex throughout the cytoplasm. Here, the effects of cold and metabolic inhibitors on cultured chondrocytes have been investigated in order to characterize further the relationship between these organelle systems. After incubation of cells for 24 h at 4° C most, but not all microtubules disappeared, indicating the existence of cold-resistant microtubules. Dictyosomes remained united in one area, until transfer of cultures to 37° C, when they dispersed throughout the cytoplasm in about one-third of the cells. In cells exposed simultaneously to cold and colchicine, microtubules disappeared completely, but spreading of dictyosomes occurred only in some cells and became generalized first upon warming. Application of the metabolic inhibitors sodium azide or sodium fluoride (10-2 M) or 2-deoxyglucose (5×10-2 M) together with sodium cyanide (10-2 M) inhibited microtubule removal by colchicine. Consequently, spreading of the Golgi complex was prevented. These findings support the concept of an important role of microtubules in the organization of the Golgi complex. Moreover, depolymerization of microtubules by colchicine appears to be an energy dependent process.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00220198
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 35
    Digitale Medien
    Digitale Medien
    Ultrastructural observation of paracrystalline aggregates of microtubules in anterior pituitary cells of the chinchilla (Chinchilla laniger) (1980)
    Springer
    Cell & tissue research 213 (1980), S. 433-440 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Anterior pituitary ; Microtubules ; Paracrystalline aggregates ; Ultrastructure ; Chinchilla
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Unusual paracrystalline aggregates of microtubules which have not been described in any other mammalian species were observed in cultured anterior pituitary cells of normal chinchillas as well as in situ in the pituitary glands of these animals. These aggregates appeared as regularly arranged tubular structures in the longitudinal plane, and as a checkerboard pattern of closely and regularly packed microtubules when examined in transverse section. Supplementation with vinblastine, colcemide or colchicine in the culture medium did not change these structures morphologically. Each unit of tubules consisted of an outer wall or parellelogram profile and an inner wall composed of a single hexagonal doublet or in a figure “8” form. The outer wall of the parallelogram was 35×28 nm in length for both sides, while the diagonal of the inner wall was 18×28 nm. These paracrystalline aggregates of microtubules in the chinchilla pituitary cells are morphologically distinct from the paracrystalline assembly of cytoplasmic microtubules induced by vinblastine or other alkaloids. The function and significance of these paracrystalline aggregates in anterior pituitary cells of the chinchilla are uncertain.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00237889
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 36
    Digitale Medien
    Digitale Medien
    Alterations of tight and gap junctions in mouse hepatocytes following administration of colchicine (1982)
    Springer
    Cell & tissue research 223 (1982), S. 187-200 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Tight junctions ; Gap junctions ; Colchicine ; Microtubules ; Liver (hepatocytes) ; Mouse
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Following the administration of colchicine at a dosage (1 mg/mouse) known to cause an antimicrotubular effect, membranes as well as tight and gap junctions of hepatocytes were studied using the thin-sectioning and freeze-fracturing technique. As early as l h after administration of colchicine the intercellular spaces were dilated and vacuoles were visible within the cytoplasm. The bile canaliculi became enlarged, and after lanthanum perfusion the tracer was found in the canalicular lumen, i.e., the tight junctions became permeable to the tracer. These findings correlated with a disorganized arrangement of the tight junctional strands of the zonula occludens. In some regions the strands showed interruptions and frequently ended freely in a diffuse pattern on the plasma membrane. Proliferation of tight junctions could be observed at various locations on the plasma membrane. The gap junctions also exhibited alterations. They showed an irregular outline with outpouchings, in addition to an enlargement in their total area from approximately 0.5 μm2 in controls up to approximately 2 μm2 in treated mice. The surface area occupied by these junctions increased from 4 % (controls) to 20% (treated) of the hepatic plasma membrane. In the cytoplasm of hepatocytes from colchicine-treated mice gap-junctional vesicles were frequently observed. In view of the antimicrotubular effect of colchicine it is tentatively suggested that the intact microtubular system of the cell may play a decisive role in the regular formation of gap and tight junctions, either directly or indirectly via microfilaments.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00221509
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 37
    Digitale Medien
    Digitale Medien
    Cytoplasmic organization and quantitation of microtubules in bovine mammary epithelial cells during lactation and involution (1982)
    Springer
    Cell & tissue research 223 (1982), S. 421-430 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Microtubules ; Cattle ; Mammary gland ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Ultrastructural examination of milk secretory cells from lactating bovine mammary gland revealed presence of numerous microtubules in the apical and paranuclear cytoplasm, particularly in the vicinity of Golgi components. Most microtubules were oriented perpendicular to the apical plasma membrane and appeared to form a framework around Golgi dictyosomal elements and secretory vesicles. In comparison, non-secretory cells obtained from involuting glands displayed few microtubules and these were randomly located throughout the cytoplasm with no particular orientation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01258499
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 38
    Digitale Medien
    Digitale Medien
    The nature of the clear zone around microtubules (1982)
    Springer
    Cell & tissue research 227 (1982), S. 609-617 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Microtubules ; Clear zones ; Cations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The clear zones seen around microtubules in transverse sections of nutritive tubes vary in size depending on whether a microtubule is bordered by ribosomes or by another microtubule. We consider that such a finding is not consistent with the current view, that the clear zone is maintained by microtubule-associated material. It can, however, be accounted for by an electrostatic repulsion between the surfaces of negatively charged microtubules and between microtubules and ribosomes which are also negatively charged. The experiments presented here, involving on the one hand the addition of cationic substances to microtubules and on the other the alteration in charge of the microtubules, support this hypothesis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00204791
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...