ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

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
    The effect of antimicrotubule agents on the growth and ultrastructure of the fungusSaprolegnia ferax and their ineffectiveness in disrupting hyphal microtubules (1975)
    Springer
    Protoplasma 85 (1975), S. 147-176 
    Details
    ISSN: 1615-6102
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In hyphae ofSaprolegnia ferax microtubules of both the mitotic spindle and the cytoplasm resist lethal or normally employed doses of colchicine, colcemid, vinblastine, griseofulvin, camphor, low temperature and up to 10,000 p.s.i. of hydrostatic pressure. 14,000 p.s.i. caused complete loss of microtubules. Descriptions of various effects on non-microtubular cellular components and colony growth rates suggest that lack of penetration of the chemical agents is not a cause of resistance and that the tested agents are not microtubule specific in their actions. At both 6,000 and 10,000 p.s.i. hydrostatic pressure microtubules could coexist with pressure induced macrotubules (approximately 42 nm diameter) and at 10,000 p.s.i. with microfilaments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01567943
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Ultrastructural changes associated with the haustorial mother cell septum during haustorium formation inUromyces phaseoli var.vignae (1975)
    Springer
    Protoplasma 84 (1975), S. 297-314 
    Details
    ISSN: 1615-6102
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ultrastructural features of developing haustoria and associated haustorial mother cell septa were examined in the cowpea rust fungus,Uromyces phaseoli var.vignae. Significant changes occurred in the septal pore apparatus, and in structures associated with the septum, during the formation of a haustorium. The originally open septal pore became plugged with osmiophilic material and, on both sides of the septum, elaborations of the plasmalemma developed whose maximum growth coincided with the close association of numerous mitochondria. Those elaborations on the haustorial mother cell side consisted of irregular whorls and tangles of membranes and disappeared prior to the formation of the penetration peg. In contrast, the more tubular protrusions on the hyphal side of the septum reached their maximum length of about 900 nm during the breaching of the host cell wall but subsequently shrank rapidly until, by the time the haustorium was mature, they and their osmiophilic matrix adjacent to the septal wall had usually disappeared. By this time, the osmiophilic plug had also disappeared and the pore now resembled that most commonly seen in other portions of the vegetative mycelium in being covered on either side by a thin layer of osmiophilic material and in being surrounded by a region of differentiated cytoplasm bordered with microbodies. Little change in this septal pore apparatus was observed as the haustorium aged until the tonoplast of the haustorial mother cell broke down. At this time the differentiated regions of the cytoplasm, and the associated microbodies, disappeared from the haustorial mother cell side of the septum. Previously undescribed stages in haustorium development were also observed during this investigation and revealed that the osmiophilic ring around the haustorium neck did not develop until the haustorium body was 2.5–3 μm in diameter. The significance of this observation, and of those associated with the haustorial mother cell septum, are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01279359
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Evidence that actin reinforces the extensible hyphal apex of the oomyceteSaprolegnia ferax (1990)
    Springer
    Protoplasma 157 (1990), S. 144-153 
    Details
    ISSN: 1615-6102
    Keywords: Actin ; Hyphae ; Morphogenesis ; Tip growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Filamentous actin in the apices of growing hyphae of the oomyceteSaprolegnia ferax is distributed such that it could compensate for weakness in the expanding apical cell wall and thus play a role in morphogenesis of the tip. The tapered extensible portion of the hyphal tip where the cell wall is plastic contains a cap of actin which differs in organization from the actin in subapical, inextensible regions of the hypha. Rapidly growing hyphae which are expected to have a longer plastic cell wall region contain longer actin caps. Furthermore, the weakest point in the hyphal apex, demonstrated by osmotic shock-induced bursting, was within the taper where the wall is plastic but never in the extreme apex where actin was most densely packed and presumably the strongest. Treatment of hyphae with cytochalasin E/dimethyl sulphoxide induced rapid changes in actin caps. Cap disruption was accompanied by transient growth rate increases, subsequent rounding and swelling of apices and a shift of osmotically induced burst points closer to the apex. These correlated changes are consistent with a role for the actin cap in tip morphogenesis. The association between regions of plasticity in the apical cell wall, the extent of the actin cap, the location of the weakest point in the apex and the effects of damage to the actin cap suggest that the cap functions to support the apex in regions where the cell wall is weak.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01322647
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Differential cytoplasm-plasma membrane-cell wall adhesion patterns and their relationships to hyphal tip growth and organelle motility (1997)
    Springer
    Protoplasma 200 (1997), S. 71-86 
    Details
    ISSN: 1615-6102
    Keywords: Actin ; Cytoplasmic migration ; Hyphae ; plasmolysis ; Tip growth ; Wall-plasma membrane-cytoskeleton adhesions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Plasmolysis of hyphae of the oomycetesSaprolegnia ferax andAchlya ambisexualis and the ascomyceteNeurospora crassa produced abundant cytoplasmic strands between the retracted cytoplasm and punctate adhesions of the plasma membrane to the cell wall. These strands formed throughout the length of mature hyphae and are the first demonstration of Hechtian strands in hyphae. In contrast to similar strands in various plant cells, the strands inSaprolegnia lacked endoplasmic reticulum but contained F-actin, suggesting similarity between their adhesion sites and focal contacts in animal cells. However, strand adhesion to the wall was insensitive to RGD-containing peptides, suggesting that the trans-membrane adhesion molecules differ from animal integrins. The pattern of plasma membrane-cell wall adhesion varied in different zones along hyphae, with broad, irregular connections in the extreme apex, uniform and continuous connection in a transition zone, and small, punctate adhesions in the mature subapical zone, suggesting differential functions in these different regions. The apical adhesions are important in tip growth, as diverse inhibitors induced concomitant changes in hyphal growth and the adhesions in the apical and transition zones. Plasmolysis also induced cytoplasmic migrations throughout hyphae. Such migrations were dominated by the central cytoplasm, and produced distorted organelles which spanned central and peripheral cytoplasm, thus supporting the idea that the adhesions in mature zones of hyphae anchor the peripheral cytoplasm and facilitate cytoplasmic and organelle migrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01280736
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Improved preservation of the form and contents of wall vesicles and the golgi apparatus in freeze substituted hyphae ofSaprolegnia (1985)
    Springer
    Protoplasma 128 (1985), S. 81-93 
    Details
    ISSN: 1615-6102
    Keywords: Cell wall synthesis ; Freeze substitution ; Fungal hyphae ; Golgi bodies ; Secretory vesicles ; Tip growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Secretory vesicles involved in cell wall synthesis (wall vesicles) and the Golgi apparatus have been compared in conventionally fixed and freeze substituted hyphae of the oomycete fungusSaprolegnia ferax. Wall vesicles freeze substituted in various fluids range from spherical to tubular and contain an intensely staining, phosphorous rich matrix. In contrast diverse conventional fixations cause artefactual constrictions in most tubular vesicles and loss of their intensely staining contents. These data are interpreted to show the existence of an intravesicular skeletal system, with cellular regulation, to determine vesicle morphology and intravesicular synthesis of a hypothetical phosphorylated glycolipid cell wall precursor. Whilst freeze substitution gives superior preservation of wall vesicle morphology, it does not demonstrate any preferential association between wall vesicles and microtubules thus suggesting that microtubules are only indirectly involved in wall vesicle transport. Freeze substitution is superior to conventional fixation for analysis of the Golgi apparatus because it uniquely reveals both differentiation of a specific single cisterna in each Golgi body and greater differences in membrane thicknesses throughout the endomembrane system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01276331
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    The behaviour of kinetochore microtubules during meiosis in the fungusSaprolegnia (1984)
    Springer
    Protoplasma 120 (1984), S. 36-42 
    Details
    ISSN: 1615-6102
    Keywords: Kinetochores ; Mitosis ; Microtubules ; Meiosis ; Saprolegnia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary InSaprolegnia, kinetochore microtubules persist throughout the mitotic nuclear cycle but, whilst present at leptotene, they disappear coincidently with the formation of synaptonemal complexes at pachytene and reform at metaphase I. In some other fungi chromosomal segregation is random in meiosis and non-random in mitosis. The attachment of chromosomes to persistent kinetochore microtubules in mitosis, but not meiosis, inSaprolegnia provides a plausible explanation for such behaviour. At metaphase I each bivalent is connected to the spindle by 2 laterally paired kinetochore microtubules whereas at metaphase II (as in mitosis) each univalent bears only one kinetochore microtubule, thus showing that all kinetochores are fully active at all stages of meiosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01287615
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Visualization of actin arrays in growing hyphae of the fungusSaprolegnia ferax (1990)
    Springer
    Protoplasma 154 (1990), S. 66-70 
    Details
    ISSN: 1615-6102
    Keywords: Actin ; Electroporation ; Hyphal growth ; Rhodamine phalloidin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have observed the distribution of filamentous actin in growing hyphae of the oomyceteSaprolegnia ferax. The actin was stained by electroporating intact hyphae in the presence of 4×10−8 M rhodamine phalloidin. Hyphae quickly recovered from electroporation and showed an apical cap of densely packed actin filaments. The pores created by the electric shock resealed in 8–10min and within 1/2 h hyphae resumed growth and appeared normal. This technique allows us to observe actin arrays during growth and may prove to be a useful tool in determining the complex roles of actin in apical growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01349537
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Microtubules around migrating nuclei in conventionally-fixed and freeze-substituted cells (1985)
    Springer
    Protoplasma 125 (1985), S. 162-172 
    Details
    ISSN: 1615-6102
    Keywords: Freeze substitution ; Microtubules ; Nuclear movement ; Fungus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The nucleus in growing hyphal tips of the fungusBasidiobolus moves forward so that it maintains position relative to the cytoplasm yet constantly migrates relative to the lateral cell wall. Quantitative. analysis of the cytoplasmic microtubules surrounding these nuclei showed that their density was uniform along the length of the nuclei and double that either ahead of or behind the nucleus. All microtubules around the nuclei were predominantly short (81% 〈1μm) and only 7% of those lateral to the nuclei came within crossbridging distance of the nuclear envelope. Because microtubules are potentially fixation labile, their characteristics were determined by both conventional fixation and freeze substitution. Both procedures gave similar results but freeze substitution preserved more microtubules ahead of the nucleus and retained twice as many nuclear envelope associated microtubules. These data provide the first quantitative evidence for improved cytoplasmic microtubule and microtubule-membrane preservation by freeze substitution and rule out some functional models for microtubule roles in organelle positioning. We conclude that the elevated microtubule density adjacent to the nuclei increases the tensile strength of the cytoplasm in this region rather than playing a direct role in moving the nucleus forward.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01281234
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Colchicine and colcemid binding components of the fungusSaprolegnia ferax (1975)
    Springer
    Protoplasma 85 (1975), S. 177-192 
    Details
    ISSN: 1615-6102
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Extracts from vegetative hyphae ofSaprolegnia ferax prepared by ammonium sulphate precipitation and D.E.A.E. cellulose chromatography, bind3H-colchicine and3H-colcemid to proteins of a molecular weight greater than 70,000. The time course of this binding shows a curve suggestive of one component which decays after 1–2 hours at 37 °C and another which is stable after 20 hours at 37 °C or 7 days at −15 °C. Comparison of specific activities suggests that the unstable component has a slightly higher affinity for colchicine but the stable one binds more colcemid. Both drugs are bound as well at 25 °C as at 37 °C.In vivo binding assays suggested greater cellular permeability to colcemid but no binding of either drug as predicted from calculations based onin vitro binding characteristics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01567944
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Fungal nuclear behavior analysed by ultraviolet microbeam irradiation (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 35-47 
    Details
    ISSN: 0886-1544
    Keywords: microbeam ; microtubules ; nucleus ; cytoskeleton ; motility ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: During hyphal tip growth in the fungus Basidiobolus magnus, nuclei normally maintain a constant distance from the advancing cell apex by continuously migrating forward. It is not known whether the mechanism that produces nuclear movement also mediates nuclear positioning, or whether these two processes are under separate control. By irradiating small cytoplasmic regions with an ultraviolet microbeam, the coordination between movement and positioning could be disrupted. Regardless of the distance of the target from the nucleus, anterior irradiations (those ahead of the nucleus) caused the nucleus to stop or move backwards, whereas posterior (behind the nucleus) irradiations caused an acceleration in the nuclear velocity. The nucleus retained its ability to move following irradiation, so there was only loss of control over normal positioning. These results suggest that movement and positioning are mediated by different mechanisms. Quantitative microtubule analysis demonstrated that microtubules in the target region had been depolymerized, but in other regions of the cell they were apparently normal. We suggest that the depolymerization of microtubules affects nuclear movement by altering the tensile strength of the cytoplasm, and that cytoskeletal tension mediate nuclear positioning.We also found that accelerated nuclear movement could occur when most of the microtubules surrounding the nucleus were depolymerized. A comparison of the microtubule population surrounding the nucleus in unirradiated versus irradiated cells suggested that microtubules move with nuclei. Therefore, the nucleus does not appear to move via a direct interaction with microtubules.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970060106
    Location Call Number Expected 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...