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  • Microtubules  (40)
  • Springer  (40)
  • 1980-1984  (40)
  • 1955-1959
  • 1925-1929
  • 1920-1924
  • 1983  (17)
  • 1980  (23)
  • 1928
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  • Springer  (40)
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  • 1980-1984  (40)
  • 1955-1959
  • 1925-1929
  • 1920-1924
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  • 1
    Electronic Resource
    Electronic Resource
    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
    Keywords: Nuclear migration ; Cleavage ; Microtubules ; Ultrastructure ; Gall midge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00848611
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  • 2
    Electronic Resource
    Electronic Resource
    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
    Keywords: Cell walls ; Cellulose ; Graptopetalum ; Microtubules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00380881
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  • 3
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    Anti-microtubular herbicides and fungicides affect Ca2+ transport in plant mitochondria (1980)
    Springer
    Planta 149 (1980), S. 336-340 
    Details
    ISSN: 1432-2048
    Keywords: Ca2+ transport ; Fungicides ; Herbicides ; Microtubules ; Mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00571167
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  • 4
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    Polarity and growth of caulonema tip cells of the moss Funaria hygrometrica (1980)
    Springer
    Planta 147 (1980), S. 405-413 
    Details
    ISSN: 1432-2048
    Keywords: Caulonema ; Cell growth (tip) ; Funaria ; Microtubules ; Organelle modification ; Polarity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00380180
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  • 5
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    Microtubules and coated vesicles in guard-cell protoplasts ofAllium cepa L. (1980)
    Springer
    Planta 149 (1980), S. 389-401 
    Details
    ISSN: 1432-2048
    Keywords: Allium ; Cell wall Coated vesicles ; Guard cells ; Microtubules ; Protoplasts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00571175
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  • 6
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    Microtubules, protoplasts and plant cell shape (1980)
    Springer
    Planta 147 (1980), S. 500-506 
    Details
    ISSN: 1432-2048
    Keywords: Cell shape ; Colchicine ; Daucus ; Immunofluorescence ; Microtubules ; Protoplasts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00380194
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  • 7
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    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
    Keywords: Colchicine ; Membrane structure ; Microtubules ; Osmotic treatment ; Plasmalemma ; Poterioochromonas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00385446
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  • 8
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    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
    Keywords: Protein ; RNA synthesis ; Microtubules ; Microfilament-disrupting drugs ; Heat ; Cold shock ; Recovery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00422302
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  • 9
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    Reduction of mechanical sensitivity in an insect mechanoreceptor correlated with destruction of its tubular body (1983)
    Springer
    Cell & tissue research 234 (1983), S. 451-461 
    Details
    ISSN: 1432-0878
    Keywords: Mechanoreception ; Sensory transduction ; Microtubules ; Vinblastine ; Insect sensillum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The modified cilium (dendrite) of epithelial mechanoreceptors of insects contains microtubules in different arrangements: (1) microtubules distributed over the entire receptor and not fixed in a special configuration, therefore called free microtubules, (2) densely packed, interconnected microtubules called the tubular body, and (3) 9 doublet microtubules. These groups of microtubules have been discussed in relation to mechanotransduction. In a preceding paper the free microtubules were proved to be not involved in mechanotransduction. In this paper the hypothesis is examined that the tubular body may be essential to mechanotransduction. For this purpose the effect of the microtubule-disassembling drug vinblastine on both the tubular body and the sensitivity is examined in a femoral mechanoreceptor of the cricket Acheta domesticus. After 6- to 26-h exposure to vinblastine the tubular body is partially or totally destroyed. Simultaneously, mechanical sensitivity decays to zero. In contrast, the pacemaker property for nerve impulses of the apical dendritic segment is only slightly altered. We conclude from these results that the tubular body is essential to mechanotransduction. Three experiments in which a (small) response persisted, despite a totally destroyed tubular body, suggest that receptor potentials can in principle be evoked without an intact tubular body. In addition to the irreversible reduction of receptor sensitivity, vinblastine causes a reversible reduction during repetitive stimulation. This adaptation is supposed to be the consequence of altered properties of the tubular body.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00213781
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  • 10
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    Microtubules, dendritic spines and spine apparatuses (1980)
    Springer
    Cell & tissue research 208 (1980), S. 171-181 
    Details
    ISSN: 1432-0878
    Keywords: Microtubules ; Dendritic spine apparatus ; Synapse ; Development ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234868
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  • 11
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    Intracellular transport in axonal microtubular domains II. Velocity profile and energetics of circumtubular flow (1983)
    Springer
    Protoplasma 114 (1983), S. 198-209 
    Details
    ISSN: 1615-6102
    Keywords: Axoplasmic transport ; Zones of exclusion ; Microtubules ; Saltatory movement ; Transport mechanisms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The microtubule is a highly efficient vectorial structure that could orient a transport force generating mechanism and also absorb the recoil produced by vectorial force generation. We have assumed that a nonspecific shear force is generated in a narrow annulus around the microtubule and have calculated the velocity profiles in the shear flow and drag flow regions that result from such a mechanism. This circumtubular flow of low visocosity cytoplasm is thought to be the basic carrier stream that produces the observed axoplasmic transport phenomena. These carrier streams are devoid of neurofilaments and form the halos or exclusion zones seen around microtubules in electron micrographs. Individual carrier streams may merge hydrodynamically to produce transport domains that are capable of moving large organelles in a saltatory manner. Exchange of material between the low viscosity transport domains and the high macroviscosity neurofilament regions produces mass fluxes akin to those found in chromatographic columns. Calculations of energy required to maintain streaming and of the energy available to the transport system show a close correspondence and demonstrate that a continuous carrier stream activity is energetically feasible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01283701
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  • 12
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    Intracellular transport in axonal microtubular domains I. Theoretical considerations on the essential properties of a force generating mechanism (1983)
    Springer
    Protoplasma 114 (1983), S. 179-197 
    Details
    ISSN: 1615-6102
    Keywords: Axoplasmic transport ; Force generating mechanism ; Microtubules ; Nerve cell ; Saltatory movement ; Viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In this article the mode of force generation of axoplasmic transport is examined on theoretical grounds. We use as criteria the experimental evidence available, the biophysical boundary conditions, energetical feasibility, and earlier theoretical treatments of this topic. The following results are obtained: 1. Comparison of the energy available and the energy required to move organelles through the viscous cytoplasm shows that the viscosities reported preclude such movement of larger vesicles or mitochondria. This suggests that transport should occur in microregions of low viscosity. 2. For ultrastructural, pharmacological, and biochemical reasons such low viscosity regions are expected to be located around microtubules. 3. Out of the 11 theoretical possibilities to generate the driving force we had to rule out four because of obvious violations of verified data. Four other modes of force generation would require one or several additional transport mechanisms to explain the entire phenomenon. Models which imply streaming of low viscosity axonal regions are found to be in good agreement with the experimental findings. 4. The comparison of intracellular sites for the location of the force generating mechanism suggests that they are located at the microtubular surface. We have shown that the properties of axoplasmic transport fit most easily the concept that the proposed low viscosity domains be located around microtubules and microtubule bundles and that these domains represent streaming regions of cytoplasm. This concept is found to be in agreement with the presented list of criteria any hypothesis of axoplasmic transport must satisfy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01283700
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  • 13
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    Structure and formation of fibrillar mucilages in seed epidermis cells (1983)
    Springer
    Protoplasma 114 (1983), S. 210-221 
    Details
    ISSN: 1615-6102
    Keywords: Cell wall structure ; Elementary fibrils ; Microtubules ; Mucilage ; Seed epidermis ; Collomia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The seed epidermis cells ofCollomia grandiflora Dougl. contain a mucilage with an amorphous and a fibrillar component. The elementary fibrils are very long and usually measure about 2.0 2.5 nm in thickness after negative staining but more than 5 nm in thin sections. They seem to consist of cellulose but are stained also with aniline blue; the emitted fluorescence light is polarized. The elementary fibrils are surrounded by the amorphous component of the mucilage and are loosely associated to form mucilage strands and, more densely, a massive spiral (or rings) which is embedded in the mucilage. During mucilage formation, microtubules run parallel with the elementary fibrils, both are oriented circumferentially. Microtubules are dense in regions where mucilage strands are formed and especially frequent where the spiral is being produced. Within the outer cell wall of the epidermis cells, lacuna-like spaces develop underneath the cuticle. They become partly filled with stacks of electron transparent lamellae, embedded in an electron dense material and resemble layers of waxes but are thicker than common “wax layers”.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01283702
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  • 14
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    Structure and formation of fibrillar mucilages in seed epidermis cells (1983)
    Springer
    Protoplasma 114 (1983), S. 222-234 
    Details
    ISSN: 1615-6102
    Keywords: Cell wall growth ; Elementary fibrils ; β-1,3 and β-1,4 glucan ; Microtubules ; Mucilage ; Seed epidermis ; Ruellia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The seed epidermis cells of differentRuellia species rupture the cuticle to form unicellular hairs. They become filled with mucilage which consists of very long elementary fibrils and an amorphous matrix. After negative staining, the elementary fibrils appear to be about 2.0–2.5 nm thick. They stain with zinc-chloride-iodine and with the fluorochromes Calcofluor White and aniline blue, perhaps indicating β-1,4 and β-1,3 glucans. The emitted fluorescence light is polarized demonstrating a longitudinal arrangement of the dye molecules. The elementary fibrils aggregate into mucilage strands which helically extend through the cell parallel to the lateral cell wall. Different helices form layers which are arranged more or less concentrically. During hair elongation and during mucilage production, microtubules are aligned parallel with the elementary fibrils. There is a 1∶1 relationship between microtubules and mucilage strands. Frequently, the strand lies opposite the microtubule. Regions without microtubules but with imcomplete mucilage strands and vice versa have also been observed. There are several possibilities to explain the structure and the staining reactions of the elementary fibrils of the mucilage on a molecular basis and the role of the microtubules during microfibril formation and orientation. The pattern of microfibrils in developing hairs is compatible with the multinet hypothesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01283703
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  • 15
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    Microtubules and their organizing centres in differentiating guard cells ofAdiantum capillus veneris (1983)
    Springer
    Protoplasma 115 (1983), S. 176-192 
    Details
    ISSN: 1615-6102
    Keywords: Microtubules ; Microtubule organizing centres ; Adiantum capillus veneris ; Guard cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The cortical cytoplasm of the young guard cells ofAdiantum capillus veneris is locally differentiated. At an early post-telophase stage, numerous microtubules diverge from the cytoplasm occupying the junctions of the midregion of the ventral wall with the periclinal ones, towards the periclinal and ventral wall faces as well as towards the inner cytoplasm. Microtubule-vesicle complexes (MVCs) are detected in these regions. Their appearance is accompanied by the initiation of local wall thickenings in the same areas. Afterwards, more distinct MVCs anchored to the plasmalemma were seen in the cortical cytoplasm of the periclinal walls, close to the growing thickenings, usually at a distance up to 3μm from them. Sometimes, they seemed to contain an electron dense substance in which the microtubules were embedded. Cortical microtubules converging from more than one direction terminate at the MVCs. Besides, the microtubule population lining the periclinal walls radiate from the regions where the above cytoplasmic formations are localized. The overlying cellulose microfibrils exhibit the same orientation. The vesicles localized at the MVCs appear to be of dictyosomal origin, very electron dense and react positively to periodic acid-thiocarbohydrazide-silver proteinate (PA-TCH-SP) test. Another population of microtubules fan out from the MVCs, entering deeper into the cytoplasm. They become associated with the nucleus and mitochondria, and traverse the peridictyosomal cytoplasm. In some instances the nucleus formed a protrusion towards an MVC and appeared associated with it via microtubules which radiate from the MVC and flank the nuclear envelope. The observations favour the hypothesis that prominent microtubule organizing centres (MTOCs) function in the cortical cytoplasm of the midregion of the periclinal walls surrounding the ventral one for a relatively long time. The MVCs and/or their adjacent plasmalemma sites may represent MTOCs or at least they specify the cortical cytoplasmic sites where microtubules are nucleated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01279808
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  • 16
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    Motility and microtubule stability of Antarctic algae at sub-zero temperatures (1983)
    Springer
    Protoplasma 115 (1983), S. 240-242 
    Details
    ISSN: 1615-6102
    Keywords: Algae ; Antarctic ; Microtubules ; Motility ; Sub-zero temperatures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Most ectothermic organisms become immobile at a few degrees above zero. The unicellular planktonic algaeDunaliella sp., andChlamydomonas sp. from Antarctic hypersaline lakes remain motile at temperatures as low as −14 °C.Pyramimonas gelidicola from the same habitat stops swimming at −10 °C but its flagella continue to beat at −14 °C. Further, the characteristic shape ofPyramimonas, which is maintained by cytoskeletal microtubules, is unaffected by such low temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01279815
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  • 17
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    Orientation of microtubules against transverse cell walls in roots ofAzolla pinnata R. Br. (1983)
    Springer
    Protoplasma 116 (1983), S. 78-85 
    Details
    ISSN: 1615-6102
    Keywords: Azolla ; Microtubules ; Root apex ; Cell expansion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Orientation of cortical microtubules against transverse cell walls was examined inAzolla root primordia at different stages of development. All transverse walls in the zone of formative divisions, where the rate of increase in girth of the root is maximal and contributed to by all cell layers, show circumferential orientation of their associated microtubules with respect to the shape of the root as a whole. In the zone of proliferative divisions, expansion of inner cortex cells remains predominantly radial and they retain the same microtubule orientation. However, in the endodermal cells which bound the stele and alter very little in radial dimension, circumferential orientation gives way to radial orientation. In none of these zones or cell types is the orientation of cortical microtubules against transverse walls “random”. Individual cells in the root can deploy their microtubules in specific, and different, orientations on different cell faces. The hypothesis that, inAzolla, nucleation of microtubules occurs along selected cell edges receives further support from the observations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01294234
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  • 18
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    Microtubule organization and morphogenesis in young spores of the mossTetraphis pellucida Hedw (1983)
    Springer
    Protoplasma 116 (1983), S. 115-124 
    Details
    ISSN: 1615-6102
    Keywords: Microtubules ; Moss ; MTOC ; Sporogenesis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Microtubule systems appear sequentially at the distal and proximal poles of tetrad members during mid-sporogenesis in the mossTetraphis pellucida Hedw. The distal microtubule system emanates from a microtubule organizing center (MTOC) located between the single plastid and the nucleus. The distal MTOC and associated microtubules, which appear immediately after cytokinesis, are ephemeral and do not appear to be associated with the deposition of exine occuring at the same time. The proximal microtubule system, which appears slightly later than the distal system, is a more stable component of mid-sporogenesis. The proximal MTOC is an irregularly lobed, patelliform aggregation of electron-dense granules located beneath the plasma membrane at the proximal spore pole. Several bundles of microtubules radiate from the proximal MTOC and traverse the cell, enclosing the nucleus in an cone of microtubules. The proximal microtubule system is thought to function in aperture development and organelle migration. The relatively large nucleus migrates a short distance in the small spore early in the tetrad stage and maintains its acentric position at the proximal pole throughout later stages of sporogenesis. The plastid migrates later in the tetrad stage from its meiotic position parallel to the distal surface to a position perpendicular to the distal surface with one tip in close proximity to the proximal MTOC. The proximal microtubule system reaches its maximum development by the end of the tetrad stage and all micrographic evidence of it is lost in the maturation stages of late sporogenesis.
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    URL: http://dx.doi.org/10.1007/BF01279828
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    Cytoskeletal control of nuclear migration and anchoring in developing cells ofMicrasterias denticulata and the change caused by the anti-microtubular herbicide amiprophos-methyl (APM) (1983)
    Springer
    Protoplasma 118 (1983), S. 75-90 
    Details
    ISSN: 1615-6102
    Keywords: Nuclear migration ; Cytoskeleton ; Microtubules ; Microfilaments ; Amiprophos-methyl (APM) ; Micrasterias
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Postmitotic nuclear migration and anchoring inMicrasterias seems to be mediated by two distinct microtubule (MT)-systems: the moving MT-system, called “posttelophase system of MT” (PTS) which arises from a node-like structure, possibly a microtubulecenter (MC) and the anchoring MT-system, called “isthmus system of MT” (IS) which surrounds the nucleus at its central position. The nucleus or parts of its envelope seems to be involved in the nucleation and orientation of these MT-systems. The moving force of the nuclear migration process obviously originates from interaction between the MT-system (PTS) and its adjacent microfilaments. Under the influence of the herbicide amiprophos-methyl (APM) a destruction of both of the MT-systems followed by a disoriented nuclear migration occurs. Recovery experiments after APM treatment revealed a reestablishment of both the PTS and the IS although a disoriented formation could often be observed. Depending on the orientation of the reestablished MT-system (PTS) either remigration of the nucleus or dislocated anchoring at one of the lobe invaginations of the cell takes place. An interaction between the nucleus and distinct sites of the plasma membrane is discussed.
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    URL: http://dx.doi.org/10.1007/BF01284749
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    Ultrastructural and biochemical characterisation of the cytoskeleton ofPhysarum polycephalum myxamoebae (1983)
    Springer
    Protoplasma 118 (1983), S. 181-191 
    Details
    ISSN: 1615-6102
    Keywords: Actin ; Cytoskeleton ; Microtubules ; Physarum polycephalum ; Tubulin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The detergent-resistant cytoskeleton ofPhysarum polycephalum myxamoebae was isolated by extraction of cells in buffers containing Triton X-100. The cytoskeleton of myxamoebae was seen to be composed of a network of 6 nm microfilaments and microtubules when examined in the electron microscope as negatively stained whole mount preparations, or in thin sections. Cytoplasmic microtubules originated from a microtubule organising centre which remained in close association both with the nucleus and centrioles in detergent-lysed preparations. Nuclear pore complexes remained attached to the nuclear surface despite the removal of nuclear membranes during Triton extraction. Preparations were examined using SDS-polyacrylamide gel electrophoresis and two-dimensional polyacrylamide gel electrophoresis. Actin and tubulin were major components of the Triton-resistant structure. Two dimensional polyacrylamide gel electrophoresis indicated the presence of tubulin and actin species in the myxamoebal cytoskeleton. Other prominent protein components had apparent relative molecular masses of approx. 27 K and 220 K. Lysis of cells in buffers containing Ca2+ resulted in the removal of microtubules from the cytoskeleton and a specific decrease in the amount of tubulin in gels of Ca2+-treated material; some tubulin spots did however remain, possibly representing centriolar tubulins.
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    URL: http://dx.doi.org/10.1007/BF01281801
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    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
    Keywords: Microtubules ; Morphogenesis ; Cell Walls ; Roots ; Colchicine ; Cell division
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
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    URL: http://dx.doi.org/10.1007/BF01276946
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    Purification of lumicolchicine for use in studies of plant development (1980)
    Springer
    Protoplasma 103 (1980), S. 105-114 
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    ISSN: 1615-6102
    Keywords: Colchicine ; Lumicolchicine ; Microtubules ; Mitosis ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
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    URL: http://dx.doi.org/10.1007/BF01276669
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    The organization of cortical microtubule arrays in the radish root hair (1980)
    Springer
    Protoplasma 103 (1980), S. 205-229 
    Details
    ISSN: 1615-6102
    Keywords: Cell wall ; Cytochalasin B ; Microfibril orientation ; Microtubules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
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    URL: http://dx.doi.org/10.1007/BF01276268
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    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 
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    ISSN: 1615-6102
    Keywords: Dikaryon ; Griseofulvin ; Microtubules ; Nuclear division ; Septal development ; Septal dissolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
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    URL: http://dx.doi.org/10.1007/BF01276277
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    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 
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    ISSN: 1615-6102
    Keywords: Cell wall ; Chytridiomycetes ; Chytridium confervae ; Cross-wall ; Microtubules ; Ribosomes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
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    URL: http://dx.doi.org/10.1007/BF01279768
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    Cell shape and microtubules in zoospores of the green algaChlorosarcinopsis gelatinosa (Chlorosarcinales): Effects of low temperature (1980)
    Springer
    Protoplasma 104 (1980), S. 283-293 
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    ISSN: 1615-6102
    Keywords: Cell shape ; Chlorosarcinopsis ; Low temperature ; Microtubules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
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    URL: http://dx.doi.org/10.1007/BF01279773
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    Distribution of cortical microtubules in tobacco protoplasts. An immunofluorescence microscopic and ultrastructural study (1980)
    Springer
    Protoplasma 105 (1980), S. 27-43 
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    ISSN: 1615-6102
    Keywords: Immunofluorescence ; Microtubules ; Plant protoplasts ; Tobacco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
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    URL: http://dx.doi.org/10.1007/BF01279847
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    Influence of the antimicrotubule agent, mebendazole, on the secretory activity of intestinal cells ofAscaridia galli (1980)
    Springer
    Protoplasma 105 (1980), S. 69-76 
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    ISSN: 1615-6102
    Keywords: Mebendazole ; Ascaridia ; Secretion ; Microtubules ; Anthelmintic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
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    Protoplasmic streaming in the giant unicellular green algaAcetabularia mediterranea (1980)
    Springer
    Protoplasma 102 (1980), S. 295-306 
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    ISSN: 1615-6102
    Keywords: Acetabularia ; Inhibitors ; Microcinematography ; Microfilaments ; Microtubules ; Protoplasmic streaming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
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    URL: http://dx.doi.org/10.1007/BF01279593
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    Sensitivity of an insect mechanoreceptor after destruction of dendritic microtubules by means of vinblastine (1983)
    Springer
    Cell & tissue research 229 (1983), S. 673-684 
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    ISSN: 1432-0878
    Keywords: Mechanoreception ; Sensory dendrite ; Microtubules ; Vinblastine ; Insect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Microtubules (Mt) are present in the modified cilium of epithelial mechanoreceptors of insects in three different arrangements: (1) 9 doublet Mt in the proximal region of the outer segment, (2) densely packed, interconnected Mt of the tubular body in the dendritic tip receiving the adequate stimuli, and (3) Mt between ciliary neck and tubular body, which are not fixed in a special configuration and therefore called free Mt. The free Mt are considered by some authors to be elements of intracellular signal transmission. This hypothesis was examined by electrophysiological and morphological studies on a tibial hair-mechanoreceptor of a cricket (Acheta domesticus). Exposure of the receptor from the apical side to vinblastine disassembled the free Mt within 2 to 4 h, while Mt of the tubular body were only little affected during this time interval. In this state of Mt disassembly (up to 7 h of application) mechanosensitivity of the receptor is only slightly reduced or not at all. The pacemaker property of the dendrite for nerve impulse is also preserved. It is concluded that the free Mt are not elements of intracellular signal transmission and are not directly involved in mechanotransduction.
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    Microtubule polarity in the nutritive tubes of insect ovarioles (1983)
    Springer
    Cell & tissue research 233 (1983), S. 133-141 
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    ISSN: 1432-0878
    Keywords: Microtubules ; Polarity ; Elongation ; Cytoplasmic transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The enormous numbers of microtubules within the nutritive tubes of hemipteran ovarioles are amenable to the hook-decoration technique for determining microtubule structural polarity, as they can be microdissected from ovarioles intact. This has allowed the correlation between the polarity of this continuously elongating complex of microtubules within a nutritive tube and the direction of transport along its length; and has shown that the plus or fast growing ends of the microtubules are all situated at the anterior end of a nutritive tube proximal to the trophic region from which synthesised materials are passed back towards the developing oocytes.
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    URL: http://dx.doi.org/10.1007/BF00222238
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    The microtubular system of crayfish retinula cells and its changes in relation to screening-pigment migration (1983)
    Springer
    Cell & tissue research 232 (1983), S. 335-348 
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    ISSN: 1432-0878
    Keywords: Cytoskeleton ; Crayfish ; Microtubules ; Photoreceptors ; Pigment migration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The organization of the microtubular system in crayfish retinula cells and its changes in relation to the light-dependent migrations of the screening pigment were studied by electron microscopy. A massive column of microtubules extends longitudinally throughout each retinula cell and its axon. The column is formed by overlapping fascicles of microtubules that originate from the vicinity of the rhabdomeres at multiple levels along the rhabdom. The pigment granules and other organelles are in general aligned with these fascicles and peripheral to the microtubular column. Close associations between microtubules and pigment granules are frequent. The total number of microtubules decreases nucleofugally from an average of about 500 at the middle of the rhabdom, to 390 at the proximal end of the rhabdom, and 240 in the axon below the basement membrane. The longitudinal distribution of microtubules was found similar for cells with the screening pigment in opposite extreme positions. In cells with the pigment in an intermediate position the number of microtubules was found to be nearly doubled in each of the mentioned levels; however, this change was correlated with a parallel increase in the cross-sectional area of the cells during the intermediate state. Thus, the density of microtubules tends to remain fairly constant throughout the light/dark adaptation cycle. These observations suggest that the microtubular system of the crayfish retinula cells constitutes a relatively stationary framework during screening-pigment movements, and could possibly act as a supportive guiding track for pigment transport.
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    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 
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    ISSN: 1432-0878
    Keywords: Chromatophores ; Light-sensitivity ; Alteration in cell shape ; Microtubules ; Echinoids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: 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.
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    Inhibition of intracellular protein transport in the mouse exocrine pancreas induced by vinblastine (1980)
    Springer
    Cell & tissue research 206 (1980), S. 73-81 
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    ISSN: 1432-0878
    Keywords: Exocrine pancreas (mouse) ; Electron microscopic autoradiography ; Microtubules ; Protein transport ; Vinblastine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: 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.
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    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 
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    ISSN: 1432-0878
    Keywords: Microtubules ; Colchicine ; Secretory vesicles ; Milk secretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: 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.
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    URL: http://dx.doi.org/10.1007/BF00224613
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    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 
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    ISSN: 1432-0878
    Keywords: Chondrocytes ; Golgi complex ; Microtubules ; Colchicine ; Metabolic inhibitors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: 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.
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    URL: http://dx.doi.org/10.1007/BF00220198
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    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 
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    ISSN: 1432-0878
    Keywords: Anterior pituitary ; Microtubules ; Paracrystalline aggregates ; Ultrastructure ; Chinchilla
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237889
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  • 38
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    Multiple effects of colchicine on oogenesis in Drosophila: Induced sterility and switch of potential oocyte to nurse-cell developmental pathway (1983)
    Springer
    Cell & tissue research 228 (1983), S. 21-32 
    Details
    ISSN: 1432-0878
    Keywords: Drosophila ; Oogenesis ; Colchicine ; Microtubules ; Sterility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Adult female fruitflies exposed to colchicine admixed to the culture medium show a series of dosage-related abnormalities that affect oogenesis and may induce sterility. Among the effects observed were decreased fecundity and hatchability of laid eggs, formation of oocytes lacking chorionic appendages, abnormal distribution and diminution in number of yolk spheres, inhibition of oocyte growth and abnormally located oocyte nuclei. Potentially the most significant effect was the development of egg chambers which contained the normal complement of 16 cells but in which all the cells had the nuclear morphology of nurse cells. The approach provides for the first time an experimental means to divert a potential oocyte into the developmental pathway of the nurse cell in a wild-type fly, and hence should be helpful in the elucidation of factors which control oocyte and nurse cell differentiation. In addition, the results serve to expand the usefulness of oogenesis in Drosophila as a model system for the evaluation of drug-induced metabolic-morphologic abnormalities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00206261
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  • 39
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    Electronic Resource
    Morphometry of the small intestinal enterocytes of the fasted rat and the effects of colchicine (1983)
    Springer
    Cell & tissue research 231 (1983), S. 289-299 
    Details
    ISSN: 1432-0878
    Keywords: Enterocytes ; Microtubules ; Colchicine ; Cell membrane ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The function of the microtubules that are present in the villus enterocytes of the mammalian small intestine is virtually unknown. In order to advance our knowledge about enterocyte microtubules, a quantitative ultrastructural comparison was carried out on enterocytes from rats injected intraperitoneally with colchicine (0.5 mg/100 g body weight) in saline and from rats injected with saline alone. Our morphometric and stereologic study demonstrates that colchicine treatment results in 1) an absolute decrease in microtubules, 2) a reduction in microvilli, essentially in length, 3) an increased thickness of the terminal web, 4) an increase in total lysosomal volume, apparently by an increased number of smaller lysosomes, and 5) a decrease in the number of Golgi lamellae. These results along with those from other studies suggest to us that enterocyte microtubules are involved in the biogenesis of microvillus plasma membrane. Our morphometric data from the saline-treated rats essentially agree with comparable data from other studies. However, comparison with comparable data from hamster enterocytes demonstrates species differences.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222181
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  • 40
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    Synaptic development and microtubule organization (1983)
    Springer
    Cell & tissue research 231 (1983), S. 93-102 
    Details
    ISSN: 1432-0878
    Keywords: Synapses ; Microtubules ; Presynaptic dense projections ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Using techniques for enhanced microtubular preservation (albumin pretreatment of Gray) occipital and pyriform cortices of rats were studied by electron microscopy at various stages of development. A close structural relationship was seen between microtubules (mts), focal membrane densities, synaptic vesicles, and presynaptic dense projections (pre-dps) during maturation. Mts were seen in the neonates to be focused onto the inner surface of immature axonic profiles merging or sometimes fragmenting there. Focal densities occur at these attachment sites and thereafter synaptic vesicles clothe the mts and abut onto these presumed primordial pre-dps. Thus, mts may contribute to the initial formation of pre-dps as well as their maintenance in the adult and may act to channel the first synaptic vesicles to the site of eventual synaptic contact and transmitter release.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00215777
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