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  • 1
    Electronic Resource
    Electronic Resource
    Wall fibrils ingerminating sporangiospores of Gilbertella persicaria (Mucorales) (1971)
    Springer
    Archives of microbiology 77 (1971), S. 366-376 
    Details
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In germinated sporangiospores of Gilbertella persicaria, negatively contrasted fibrils, 20–70 Å diam, are seen in thin sections of the inner vegetative wall that is continuous with the germ tube wall. The fibrils are randomly oriented in a loose network in this wall and in the germ tube wall. Germ tubes have an additional surface layer of fine, positively contrasted fibrils which appear as a nap-like coating on the hyphae. Patterns of wall fibril orientation are not revealed by transverse sections of spore and germ tube walls, whereas oblique and tangential sections are favorable for examining cell wall architecture in situ. Staining patterns show textural and compositional differences among various wall layers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425039
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  • 2
    Electronic Resource
    Electronic Resource
    Chitosomes from the wall-less “slime” mutant of Neurospora crassa (1984)
    Springer
    Archives of microbiology 139 (1984), S. 105-112 
    Details
    ISSN: 1432-072X
    Keywords: Cell disruption ; Chitin-synthetase localization ; Chitosomes ; Neurospora crassa ; Plasma membrane ; Slime mutant ; Wild-type ; Zymogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cell-free extracts from the wall-less slime mutant of Neurospora crassa and the mycelium of wild type exhibit similar chitin synthetase properties in specific activity, zymogenicity and a preferential intracellular localization of chitosomes. The yield of chitosomal chitin synthetase from sline cells was essentially the same irrespective of cell breakage procedure (osmotic lysis or ballistic disruption) —an indication that chitosomes are not fragments of larger membranes produced by harsh (ballistic) disruption procedures. The plasma membrane fraction, isolated from slime cells treated with concanavalin A, contained only a minute portion of the total chitin synthetase of the fungus. Most of the activity was in the cytoplasmic fraction; isopycnic sedimentation of this fraction on a sucrose gradient yielded a sharp band of chitosomes with a buoyant density=1.125 g/ cm3. Approximately 76% of the total chitin synthetase activity of the slime mutant was recovered in the chitosome band. Because of their low density, chitosomes could be cleanly separated from the rest of the membranous organelles of the fungus. Apparently, the lack of a cell wall in the slime mutant is not due to the absence of either chitosomes or zymogenic chitin synthetase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00401983
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  • 3
    Electronic Resource
    Electronic Resource
    Cytoplasmic vesicles in germinating spores ofGilbertella persicaria (1971)
    Springer
    Protoplasma 72 (1971), S. 381-397 
    Details
    ISSN: 1615-6102
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Germ tube apices ofGilbertella persicaria contain cytoplasmic vesicles, similar to the secretory vesicles found at the tips of vegetative hyphae. The vesicles are present at all stages of development, from the time of germ tube initiation to the establishment of branched hyphae. In contrast to the abundant vesicles at tips of established hyphae, the germ tubes have only a few apical vesicles in a layer next to the plasma membrane. When germinated spores are treated by washing and centrifuging prior to fixation, the cytoplasm is often disrupted near the apex, and the clusters of apical vesicles disappear. The findings indicate the delicate nature of hyphal tips and the necessity of avoiding prefixation stresses in order to preserve the apical apparatus of growing hyphae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01289510
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  • 4
    Electronic Resource
    Electronic Resource
    Molecular resolution images of amino acid crystals with the atomic force microscope (1988)
    [s.l.] : Nature Publishing Group
    Nature 332 (1988), S. 332-334 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In the two years since its invention, the atomic force microscope (AFM)1 has already been developed into a powerful analytical instrument. It has been used to obtain atomic resolution images of graphite2"4 and other layered and non-layered materials5'6, to image the molecules in an organic ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/332332a0
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  • 5
    Electronic Resource
    Electronic Resource
    Diversity and dynamics of the Spitzenkörper in growing hyphal tips of higher fungi (1996)
    Springer
    Protoplasma 195 (1996), S. 90-111 
    Details
    ISSN: 1615-6102
    Keywords: Cell polarity ; Diversity ; Cytoplasmic dynamics ; Fungi ; Hyphal tip growth ; Spitzenkörper ; Video-enhanced microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The Spitzenkörper, located in the apex of growing hyphae of septate fungi, has been portrayed previously as a spheroid complex containing a cluster of apical (secretory) vesicles which sometimes encloses a differentiated core area. With the aid of computer-enhanced video microscopy and phase-contrast optics, we studied 32 fungi in the Ascomycetes, Deuteromycetes, Hyphomycetes, Basidiomycetes, and Agonomycetes. The Spitzenkörper appeared as a highly dynamic and pleomorphic multicomponent complex capable of changing shape, size, and position within the hyphal apex during growth. The main theme of this study is to demonstrate two kinds of morphological diversity/variation in Spitzenkörper from diverse fungi: (a) inherent diversity — Spitzenkörper features characteristic of particular fungi, and (b) dynamic pleomorphism — gradual or rapid changes in size, shape, and position of the Spitzenkörper within a single hyphal tip. Several components associated with the Spitzenkörper were identified: (a) vesicle cluster, (b) vesicle cloud, (c) differentiated core region(s) within the Spitzenkörper, (d) apical granules, (e) cytoplasmic filaments. Eight morphological patterns of Spitzenkörper organization are described in the higher fungi based on the shape and distribution of their components. An additional (ninth) pattern was recognized in the chytridiomyceteAllomyces macrogynous from recent work by others. All these patterns appeared to be conserved at the genus level. In all patterns but one, a core region was observed by light microscopy. The Spitzenkörper not only exhibited spontaneous dynamic pleomorphism but also reacted to stress conditions (light, mechanical, and electrical fields). These reactions include migration of the Spitzenkörper back into the subapical zone and/or disassembly of its components. The understanding and conceptualization of this dynamic complex is problematic and should remain flexible enough to encompass the diversity of Spitzenkörper patterns and the dynamic pleomorphism of this specialized apical apparatus which appears to drive hyphal tip growth in the higher fungi.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01279189
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  • 6
    Electronic Resource
    Electronic Resource
    Satellite Spitzenkörper in growing hyphal tips (1995)
    Springer
    Protoplasma 188 (1995), S. 85-103 
    Details
    ISSN: 1615-6102
    Keywords: Hyphal tip growth ; Spitzenkörper ; Secretion ; Secretory vesicles ; Video-enhanced microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Growing hyphal tips of higher fungi contain an organized assemblage of secretory vesicles and other cell components collectively known as the Spitzenkörper. Until now, the Spitzenkörper has been portrayed as a single spheroid complex located near the apical cell wall. This study demonstrates the occurrence of multiple Spitzenkörper in growing hyphal apices imaged by video-enhanced phase-contrast microscopy. In addition to the main Spitzenkörper, smaller satellite Spitzenkörper arise a few micrometers behind the apical pole. Four developmental stages were identified: (a) the satellites first appeared as faint phase-dark plaques next to the plasma membrane, (b) gradually increased in size and assumed an ovoid profile, (c) they migrated to the hyphal apex, and (d) finally they merged with the main Spitzenkörper. After the merger, the main Spitzenkörper temporarily increased in size. Satellites were observed in 14 fungi, most of which had relatively large (5–10 μm diam.), fast-growing hyphae (2–33 μm/min elongation rate). The average frequency of in-focus satellites was 7+/min forFusarium culmorum and 11+/min forTrichoderma viride. As with the main Spitzenkörper, satellites were present only in growing cells. They were transient and remained visible for 3–8 s before merging with the main Spitzenkörper. Within the hyphae, satellites travelled up to six times faster than the average cell elongation rate. Multiple satellites sometimes occurred simultaneously; up to three were seen within a hyphal apex at the same time. Localized cell enlargement occurred next to stationary satellites, suggesting that satellite Spitzenkörper are functional as sources of new cell surface before they reach the main Spitzenkörper; therefore, they account for some variations in the profiles of the growing hyphae. By electron microscopy, satellites consisted of small clusters of apical vesicles surrounding a group of microvesicles located next to the plasma membrane. The identification and behavior of the satellites represent clear evidence of directional mass transport of vesicles toward the hyphal apex. Our observations indicate that satellites are a common phenomenon in growing hyphal apices of septate fungi and that they contribute to growth of the hyphal apex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01276799
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  • 7
    Electronic Resource
    Electronic Resource
    Structure, differentiation, and multiplication of Golgi apparatus in fungal hyphae (1996)
    Springer
    Protoplasma 194 (1996), S. 250-274 
    Details
    ISSN: 1615-6102
    Keywords: Golgi apparatus ; Dictyosome ; Endomembrane system ; Fungus ; Hypha ; Pythium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Golgi apparatus in subapical regions of hyphae consist of paranuclear dictyosomes with 4–5 cisternae each. Transverse and tangential sections provide ultrastructural evidence for a three-dimensional architectural model of the Golgi apparatus and a stepwise mechanism for dictyosome multiplication. The dictyosomes are polarized, with progressive morphological and developmental differentiation of cisternae from the cis to the trans pole. Small membrane blebs and transition vesicles provide developmental continuity between the nuclear envelope and the adjacent dictyosome cisterna at the cis face. Cisternae are formed as fenestrated plates with extended tubular peripheries. The morphology of each cisterna depends on its position in the stack, consistent with a developmental gradient of progressive maturation and turnover of cisternae. Mature cisternae at the trans face are dissociated to produce spheroid and tubular vesicles. Evidence in support of a schematic sequence for increasing the numbers of dictyosomes comes from images of distinctive and unusual forms of Golgi apparatus in hyphal regions where nuclei and dictyosomes multiply, as follows: (a) The area of the nuclear envelope exhibiting “forming-face” activity next to a dictyosome expands, which in turn increases the size of cisternae subsequently assembled at the cis face of the dictyosome. (b) As subsequent large cisternae are formed and mature as they pass through the dictyosome, an entire dictyosome about twice normal size is built up. The number of cisternae per stack remains the same because of continuing turnover and loss of cisternae at the trans face, (c) This enlarged dictyosome becomes separated into two by a small region of the nuclear envelope next to the cis face that acquires polyribosomes and no longer generates transition vesicles, (d) As a consequence, assembly of new dictyosomes is physically separated into two adjacent regions, (e) As.the enlarged cisternae are lost to vesiculation at the trans pole, they are replaced by two separate stacks of cisternae with typical “normal” diameters, (f) The net result is two adjacent dictyosomes where one existed previously. Dictyosome multiplication is thus accomplished as part of the normal developmental turnover of cisternae, without interrupting the functioning of the Golgi apparatus as it continues to produce new secretory vesicles from mature cisternae at the trans face. Coordination of Golgi apparatus multiplication with nuclear division ensures that each daughter nucleus receives a complement of paranuclear dictyosomes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01882032
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  • 8
    Electronic Resource
    Electronic Resource
    Continuity between cytoplasmic endomembranes and outer mitochondrial membranes in fungi (1971)
    Springer
    Protoplasma 73 (1971), S. 15-34 
    Details
    ISSN: 1615-6102
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Several types of intimate association are shown between endoplasmic reticulum or endoplasmic reticulum-like membranes and the outer membranes of mitochondria in fungal hyphae. These include close physical association, contact, thread-like continuity, and direct luminal continuity. Membranes are smooth surfaced in the immediate region of association or continuity, and some have ribosomes at other sites along their surfaces. The continuities represent sites of membrane interaction which may facilitate exchange between adjacent membrane components. Additional continuities are shown between mitochondria and other endomembrane components. Observations are discussed in relation to the body of information linking mitochondria and endoplasmic reticulum in a variety of eukaryotic cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01286408
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  • 9
    Electronic Resource
    Electronic Resource
    Ultrastructural specialization at the host-pathogen interface in rust-infected flax (1972)
    Springer
    Protoplasma 74 (1972), S. 271-305 
    Details
    ISSN: 1615-6102
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Ultrastructure of the association between the rust fungus, Melampsora lini, and a compatible variety of flax, Linum usitatissimum, was studied to clarify the structural relationships and interactions at the site of host penetration and at the host-parasite interface. Results of freeze-etching as well as a special section-staining procedure consisting of periodate-chromate-phosphotungstate (PACP) are shown with a host-parasite combination for the first time. The host plasma membrane is invaginated by the fungus and forms a continuous boundary around the fungal haustoria which penetrate the host cells. No morphological continuities are observed linking the protoplasts of host and fungus. With both freeze-etching and the PACP stain, the invaginated portion of the host plasma membrane at the host-parasite interface shows distinctive features that are not characteristic of the non-invaginated portion of the membrane. This localized specialization of host plasma membrane in response to the fungus appears as a significant and consistent feature of the host-parasite interaction. The host plasma membrane is separated from the haustorial wall by an amorphous layer of sheath material which covers the body but not the neck of the haustorium. This sheath provides the environment in which the haustorium exists and functions during the course of the host-parasite association. Occasionally, a collar of wall-like material derived from the host cell forms around the haustorial neck. The collar is continuous with the host wall and is distinct and discontinuous from the haustorial sheath. In fewer than 5% of the infected cells this wall material encases entire haustoria. The fungal wall is structurally specialized around the site of host penetration, and it becomes intimately associated with the host wall where the fungus penetrates into the lumen of the host cell. During penetration, the host and fungal walls appear to be fused so that the interface between them is not clearly delineated. The haustorial wall is continuous, via the haustorial neck, with the wall of the haustorial mother cell which lies outside the host cell. Different staining properties reveal this wall continuum to consist of several well-defined regions having different structure or composition. A ring of fungal wall material midway along the haustorial neck stains densely with lead citrate, but is preferentially etched away by periodic acid. The neck ring denotes a transition in the staining reaction of the fungal wall, from that present in the region of host penetration to that of the wall surrounding the haustorium. The findings demonstrate specialization of the fungal wall in the area of host penetration as well as specialization of the host plasma membrane at the host-parasite interface to a degree not previously realized from ultrastructural information.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01282533
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  • 10
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    Chitosomes from the wall-less ?slime? mutant of Neurospora crassa (1984)
    Springer
    Details
    Publication Date: 1984-10-01
    Print ISSN: 0302-8933
    Electronic ISSN: 1432-072X
    Topics: Biology
    Published by Springer
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