Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Metabolic inhibitors and mitosis: II. Effects of dinitrophenol/deoxyglucose and nocodazole on the microtubule cytoskeleton (1986)
    Springer
    Protoplasma 131 (1986), S. 60-74 
    Details
    ISSN: 1615-6102
    Keywords: Mitosis ; ATP ; Metabolic inhibitors ; Spindle ; Microtubule
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary To examine the effects exerted on the microtubule (MT) cytoskeleton by dinitrophenol/deoxyglucose (DNP/DOG) and nocodazole, live PtK1 cells were treated with the drugs and then fixed and examined by immunofluorescence staining and electronmicroscopy. DNP/DOG had little effect on interphase MTs. In mitotic cells, kinetochore and some astral fibers were clearly shortened in metaphase figures by DNP/DOG. Nocodazole rapidly broke down spindle MTs (except those in the midbody), while interphase cells showed considerable variation in the susceptibility of their MTs. Nocodazole had little effect on MTs in energy-depleted (DNP/DOG-treated) cells. When cytoplasmic MTs had all been broken down by prolonged nocodazole treatment and the cells then released from the nocodazole block into DNP/DOG, some MT reassembly occurred in the ATP-depleted state. MTs in permeabilized, extracted cells were also examined with antitubulin staining; the well-preserved interphase and mitotic arrays of MTs showed no susceptibility to nocodazole. In contrast, MTs suffered considerable breakdown by ATP, GTP and ATPγS; AMPPNP had little effect. This susceptibility of extracted MT cytoskeleton to nucleotide phosphates was highly variable; some interphase cells lost all MTs, most were severely affected, but some retained extensive MT networks; mitotic spindles were diminished but structurally coherent and more stable than most interphase MT arrays. We suggest that: 1. in the living cell, ATP or nucleotide triphosphates (NTPs) are necessary for normal and nocodazole-induced MT disassembly; 2. the NTP requirement may be for phosphorylation; 3. shortening of kinetochore fibers may be modulated by compression and require ATP; 4. many of these results cannot be accomodated by the dynamic equilibrium theory of MT assembly/disassembly; 5. the use and role of ATP on isolated spindles may have to be reevaluated due to the effects ATP has on the spindle cytoskeleton of permeabilized cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01281687
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Metabolic inhibitors and mitosis: III. Effects of dinitrophenol on spindle disassembly inPinnularia (1986)
    Springer
    Protoplasma 132 (1986), S. 85-89 
    Details
    ISSN: 1615-6102
    Keywords: Mitosis ; ATP, Microtubules ; Spindle ; Metabolic inhibitors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary At telophase in the diatomPinnularia, the two half spindles that comprise the central spindle, separate and then disassemble unidirectionally from the end formerly in the central overlap, back to the pole (Soranno andPickett-Heaps 1982). The metabolic inhibitors dinitrophenol plus deoxyglucose were applied to cells at telophase, depleting their ATP levels at the early stages of half-spindle disassembly; the cells were maintained in this state for 5 minutes, before the inhibitors were washed out. Disassembly of the half spindles, as judged from their birefringence, ceased in ATP-depleted conditions, and recommenced soon after the inhibitors were removed, going to completion quite rapidly. We conclude that disassembly of these MTsin vivo requires energy, probably in the form of ATP.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01275794
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Flagellar transformation in the heterokontEpipyxis pulchra (Chrysophyceae): Direct observations using image enhanced light microscopy (1988)
    Springer
    Protoplasma 145 (1988), S. 47-54 
    Details
    ISSN: 1615-6102
    Keywords: Flagella ; Flagellar apparatus ; Epipyxis ; Chrysophyceae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Cells ofEpipyxis pulchra possess two heteromorphic flagella that differ markedly in function, particularly during motility and prey capture. Flagellar heterogeneity is achieved during the course of at least three cell cycles. Prior to cell division, cells produce two new long, hairy flagella while the parental long flagellum is transformed into a new short, smooth flagellum. The parental short flagellum remains a short flagellum for this and subsequent cell division cycles. Although flagellar transformation requires only two cell cycles, developmental differences exist between daughter cells and the maturation of a flagellum/basal body requires at least three cycles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01323255
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Transformation of the flagella and associated flagellar components during cell division in the coccolithophoridPleurochrysis carterae (1988)
    Springer
    Protoplasma 145 (1988), S. 37-46 
    Details
    ISSN: 1615-6102
    Keywords: Microtubules ; Basal bodies ; Flagellar apparatus ; Prymnesiophyceae ; Mitosis ; Pleurochrysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Immunofluorescence microscopy, conventional and high voltage transmission electron microscopy were used to describe changes in the flagellar apparatus during cell division in the motile, coccolithbearing cells ofPleurochrysis carterae (Braarud and Fagerlund) Christensen. New basal bodies appear alongside the parental basal bodies before mitosis and at prophase the large microtubular (crystalline) roots disassemble as their component microtubules migrate to the future spindle poles. By prometaphase the crystalline roots have disappeared; the flagellar axonemes shorten and the two pairs of basal bodies (each consisting of one parental and one daughter basal body) separate so that each pair is distal to a spindle pole. By late prometaphase the pairs of basal bodies bear diminutive flagellar roots for the future daughter cells. The long flagellum of each daughter cell is derived from the parental basal bodies; thus, the basal body that produces a short flagellum in the parent produces a long flagellum in the daughter cell. We conclude that each basal body in these cells is inherently identical but that a first generation basal body generates a short flagellum and in succeeding generations it produces a long flagellum. At metaphase a fibrous band connecting the basal bodies appears and the roots and basal bodies reorient to their interphase configuration. By telophase the crystalline roots have begun to reform and the rootlet microtubules have assumed their interphase appearance by early cytokinesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01323254
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    The effect of drugs on diatom valve morphogenesis (1989)
    Springer
    Protoplasma 149 (1989), S. 130-143 
    Details
    ISSN: 1615-6102
    Keywords: Colchicine ; Cytochalasin D ; Diatom ; Microtubule center ; Morphogenesis ; Valve morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The effects of various drugs on cell wall (valve) morphogenesis was investigated in three species of diatoms (Pinnularia spp., Surirella robusta, andHantzschia amphioxys) using light microscopy (LM) and scanning electron microscopy (SEM). Treatment ofSurirella with the microtubule (MT) disrupting agent colchicine during early valve formation results in a characteristic malformation of the valve, whereby part of the normally circumferential raphe canal forms as an abnormal protruding lip on the valve surface, located up to ∼ 20 μm from the edge of the valve. The position of this malformed lip coincides with the location of a microtubule center (MC) at the time of colchicine addition, suggesting that the MC may play a direct role in positioning the tip of the raphe canal during valve formation. The migration of this MC to the tip of the cell during early valve morphogenesis is reversibly inhibited by the metabolic inhibitor 2-4-dinitrophenol (DNP). The effect of colchicine onPinnularia valve formation is less severe, causing occasional malformation of the raphe, but little if any lateral displacement. InHantzschia, colchicine has no effect on the positioning of the raphe, but prolonged exposure causes fusion of the raphe canal with the valve face. Cochicine treatment also results in the absence of the normal curvature at the central interruption in the raphe, as well as abnormal pore formation in this central area. Addition of cytochalasin D during early valve formation inHantzschia causes the raphe canal to form in the center of the valve face, suggesting that the normal translocation of the raphe canal to the valve edge is actindependent. Comparison of valves from control and cytochalasintreatmentHantzschia suggest that the pore spacing within the valve is determined by the position relative to the raphe, and does not depend on whether to pores form on the side (mantle) or the face of the mature valve.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01322985
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    UV microbeam irradiations of the mitotic spindle I. The UV-microbeam apparatus (1989)
    Springer
    Protoplasma 153 (1989), S. 62-70 
    Details
    ISSN: 1615-6102
    Keywords: Mitosis ; Ultraviolet microbeam
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We describe the assembly of a UV microbeam microscope based on a Zeiss IM35 inverted microscope. The important UV transmitting elements are standard UV epifluorescence attachments available from Zeiss; the main modification involves fitting an adjustable slit in place of the field diaphragm. We describe how to align and focus the UV source for optimal irradiations. Our current version of this machine is also fitted with a monochromator and using monochromatic UV light, we can reproduceably create Areas of Reduced Birefringence in spindle fibres with ca. 2–3 s irradiations, while continually observing the fibres. The microscope is stable and easy to set up, allowing many consecutive experiments to be done, including multiple irradiations on the one cell. In conjunction with video image processing techniques, the cells can be observed continuously using polarising, Nomarski or other optical systems. Some preliminary observations demonstrating the versatility of the machine are described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01322466
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    The kinetochore fiber structure in the acentric spindles of the green algaOedogonium (1987)
    Springer
    Protoplasma 137 (1987), S. 29-44 
    Details
    ISSN: 1615-6102
    Keywords: Kinetochore fiber ; Microtubules ; Mitosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The microtubule (MT) arrangement in three kinetochore fibers in the acentric spindles of the green algaOedogonium cardiacum were reconstructed from serial sections of prometaphase and metaphase cells. The majority of the MTs attached to the kinetochore (kMTs) are relatively short, extending less than a third of the distance to the putative spindle pole region, and none extended the full distance. Fine filaments and a matrix described earlier (Schibler andPickett-Heaps 1980) were associated with the MTs all along the fibers. Live cells ofOedogonium were also studied by time lapse cinematography for correlation with the ultrastructural observations. Late prometaphase and metaphase kinetochore fibers appear to move independently as if unattached at their poleward ends. These observations suggest that kinetochore fibers inOedogonium are not attached to a specific pole structure from late prometaphase until the inception of anaphase. The results are discussed with reference to spindle structure and function in general.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01281174
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Metabolic inhibitors and mitosis: I. Effects of dinitrophenol/deoxyglucose and nocodazole on the live spindle (1986)
    Springer
    Protoplasma 131 (1986), S. 47-59 
    Details
    ISSN: 1615-6102
    Keywords: Mitosis ; ATP ; Metabolic inhibitors ; Spindle ; Nocodazole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Dinitrophenol and deoxyglucose (DNP/DOG) were used to investigate the effects of ATP depletion on mitotic PtK1 cells. Direct determination of cellular ATP levels showed that the drop of ATP induced by DNP/DOG was rapid; recovery to normal ATP levels was equally rapid once DNP/DOG was removed. On addition of DNP/DOG to live cells, cytoplasmic activity ceased; interphase and prophase cells showed little other response to DNP/DOG. During prometaphase, DNP/DOG induced a pronounced movement of oscillating, monopolar chromosomes towards the spindle poles. As chromosomes became bipolarly attached, DNP/DOG caused the spindle poles themselves to move together. By metaphase, DNP/DOG-treatment led to significant shortening of the spindle which remained intact. DNP/DOG rapidly stopped anaphase chromosome movement and cytokinesis. Nocodazole (NOC) caused the rapid breakdown of the mitotic spindle; prometaphase chromosomes clustered at the poles and in metaphase cells, the poles were drawn towards the chromosomes as the spindle became disorganized. When cells were pretreated with DNP/DOG and then NOC/DNP/DOG, nocodazole did not break down the spindle. When nocodazole was applied first to break down spindle MTs then DNP/DOG was added to the nocodazole, a second contraction was often induced by the DNP/DOG in the absence of spindle microtubules (MTs). Chromosomes expanded appreciably outwards from the poles when the DNP/DOG was removed, even when the cells remained in nocodazole.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01281686
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Cell division and morphogenesis of the labiate process in the centric diatomDitylum brightwellii (1988)
    Springer
    Protoplasma 143 (1988), S. 139-149 
    Details
    ISSN: 1615-6102
    Keywords: Labiate process ; Raphe
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Cells of the centric diatomDitylum brightwellii were filmed undergoing cell division and valve secretion, and were fixed for transmission electron microscopy. Attention was directed particularly at the origin of the Labiate Process Apparatus (LPA). As reported previously (li andVolcani 1985 a), the nucleus, centrally situated during interphase, moves laterally to undergo mitosis against the girdle bands. We describe the spindle which splits up into numerous fibres of overlapped polar microtubules (MTs) by metaphase. The chromosomes are diffuse and the spindle elongates rapidly during anaphase. A complex of organelles is found at the poles and ill-defined, dense material extends to the nearby plasmalemma from prophase on. The two Silica Deposition Vesicles (SDVs) are initiated during anaphase close to the poles and by midcleavage, the dense LPA arises on each SDV close to dense polar material. After cleavage, the daughter protoplasts round up and the SDV, already containing a nascent valve, expands over the cleavage furrow. The labiate process, a long straight hollow tube of silica, is rapidly (ca. 25 minutes) secreted from directly under the LPA; a fibrous plug (polysaccharide?) always appears in the SDV immediately adjacent to the LPA during the initiation of this secretion. The ill-defined Microtubule-Organizing Center (MC) from the spindle pole remains close to the LPA and in it can be seen the tiny presumptive primordial spindle on the nuclear envelope. The raphe and the labiate process (LP), both highly differentiated apertures in the valve, probably function in a specialized form of the mucilage secretion involved in generation of movement in raphid diatoms, and in a simple form of movement in some centrics. Morphogenesis of the LP is associated with the LPA while differentiation of the raphe is almost associated with the MC; both MC and LPA have an intimate ontological relationship with the spindle pole and the postmitotic cytoskeletal system of MTs. This association also is seen in the formation of the LP in an araphid pennate,Diatoma (work in progress). Therefore, from functional, morphogenetic and ontogenetic observations, we support the proposal that the raphe of pennate diatoms arose from the LP of centric diatoms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01291158
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...