The cytoplasmic organization of hyphal tip cells in the fungusAllomyces macrogynus

Vargas, Maria M.; Aronson, Jerome M.; Roberson, Robert W.

doi:10.1007/bf01378938

Cited by 56 publications

(49 citation statements)

References 43 publications

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“…The presence of Spitzenköper in chytridiomycetes was not known until recently. In Allomyces macrogynus, Vargas et al observed the presence of a spherical zone in the tip region of growing hyphae and showed it to be the Spitzenkörper equivalent in higher fungi (Vargas et al, 1993). We have observed a similar structure, a spherical pit of about 2.4-3 µm diameter, in the exclusion zone of the growing hyphal tips.…”

Section: Discussionsupporting

confidence: 72%

“…Cytoskeletal proteins, particularly the actins and tubulins, have also been shown to be abundantly present in the growing hyphal tips (Raudaskoski et al, 1991;Barja et al, 1991;Huber and Ojha, 1994). The ultrastructural studies of hyphal tips had already shown an abundance of microtubules and microfilament in the tip region of the hyphae (Roos and Turian, 1977;Howard, 1981;Vargas et al, 1993), suggesting that these elements are probably involved in the maintenance of form and growth of the tips. Our finding that CDP II localized to the same region led us to assume that this colocalization must have some meaning.…”

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confidence: 99%

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Spatial and cellular localization of calcium-dependent protease (CDP II)inAllomyces arbuscula

Ojha

Barja

2003

Journal of Cell Science

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Immunogold labeling of calcium-dependent neutral protease II (CDPII) with specific antibodies in near median longitudinal ultrathin sections of Allomyces arbuscula showed that the enzyme is predominantly localized in the growing hyphal and rhizoidal apices. The tips in both cell type had more enzyme than the distal regions and showed a gradient distribution. Labeling of the ultrathin sections and western blot analysis of purified subcellular fractions showed that CDPII is mainly cytosolic. Catalytic activity of the enzyme measured with synthetic substrate (Bz-Arg-pNA) showed that 90% of its activity is present in the soluble fraction, although a small amount is associated with the nuclei (0.2%), plasma membranes (0.7%) and microsomes (3.9%). This association is discussed in the context of the functional role of the enzyme and its possible localized activation. Western blot analysis of the crude extract and indirect immunofluorescence of the fixed permeabilized hypahe after treatment with CDPII showed that theα-tubulin is a specific target of the enzyme.

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Section: Discussionsupporting

confidence: 72%

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confidence: 99%

Spatial and cellular localization of calcium-dependent protease (CDP II)inAllomyces arbuscula

Ojha

Barja

2003

Journal of Cell Science

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“…Examination of hyphal tips of Magnaporthe grisea (Bourett and Howard, 1991) and Allomyces macrogynus (Vargas et al, 1993) revealed actin filaments and microtubules in the Spitzenkö rper region. Although the role of cytoskeletal elements in Spitzenkö rper structure and function is not well established, several reports suggest that the cytoskeleton may propel and control the motion of the Spitzenkö rper.…”

Section: Spitzenkö Rper Behaviormentioning

confidence: 99%

Apical Branching in a Temperature Sensitive Mutant ofAspergillus niger

Reynaga-Peña

Bartnicki-García

1997

Fungal Genetics and Biology

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“…Of these early studies, that of Grove and Bracker (26) stands out in providing the most detailed analysis of the ultrastructural organization of hyphal tips, as well as illustrating the variable morphology of the Spitzenkör-per among different groups of fungi. Ultrastructural preservation took a quantum leap forward with the development and use of rapid cryofixation and freeze-substitution protocols to prepare hyphal cells for TEM (36,37,38), which set the benchmark for subsequent ultrastructural studies (33,34,49,58,59,60,68). All studies of hyphal tip ultrastructure by TEM have demonstrated that the Spitzenkörper is a complex, multicomponent structure dominated by vesicles (Fig.…”

Section: Microscopymentioning

confidence: 99%

Polarisome Meets Spitzenkörper: Microscopy, Genetics, and Genomics Converge

et al. 2005

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7The impact of filamentous fungi on human welfare has never been greater. Fungi are acknowledged as the most economically devastating plant pathogens (1) and are attaining increasing notoriety for their ability to cause life-threatening infections in humans (57,71), and fungal products sustain a billiondollar manufacturing industry (70). The tools available to study filamentous fungi are more sophisticated than ever and include the complete annotated genome sequences of multiple filamentous fungi (12), resources being made available through various functional genomics projects, and advanced bioimaging methods, including high-resolution live-cell imaging (20, 32) and electron tomography (19,50). The increasing impact of filamentous fungi, along with the rediscovery of pseudohyphal growth in yeast (22), has focused attention on the molecular mechanisms underlying hyphal morphogenesis.Attempts to understand hyphal morphogenesis have historically followed two different lines of investigation. Microscopists have defined, with increasing detail, the subcellular organization of the hyphal tip. This led to the description of the Spitzenkörper, an apical cluster of vesicles, cytoskeletal elements, and other proteins, which plays a crucial role in hyphal extension (4). Geneticists have identified gene products required for hyphal morphogenesis by characterizing morphological mutants (51,52). Initial studies in the laboratories of Beadle, Tatum, and colleagues attempted to link morphogenesis to specific biochemical pathways. More recent screens have identified a multitude of signaling and cytoskeletal functions required for hyphal extension (62, 72).In the past few years, comparative genomics efforts have allowed fungal biologists interested in hyphal morphogenesis to exploit the wealth of knowledge about polarized growth in the yeast Saccharomyces cerevisiae. Many informative homologies between filamentous fungi and yeast have been uncovered. Notably, this includes several components of a multiprotein complex termed the polarisome (28), which regulates microfilament formation at polarized growth sites in yeast (61).Perhaps more importantly, several gene products involved in hyphal morphogenesis have been shown to have no homologue outside of the filamentous fungi. This emphasizes the potential novelty of the mechanisms underlying hyphal morphogenesis. In this review, we summarize past efforts to understand hyphal morphogenesis and pose a series of questions designed to focus future efforts in this area. HYPHAL MORPHOGENESIS: A BRIEF OVERVIEWFungal hyphae originate from either a germinating spore or another hypha (i.e., during branch formation). Initially, an axis of polarity is established from a symmetrically expanding spore or hyphal compartment. Subsequently, cell surface expansion is restricted to the specified axis, thereby leading to the formation of a polarized hypha that displays a gradient of expansion that peaks at the tip (2,15,25,30,52). Maintenance of the polarity axis allows hyphae to achieve a linear extens...

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The cytoplasmic organization of hyphal tip cells in the fungusAllomyces macrogynus

Cited by 56 publications

References 43 publications

Spatial and cellular localization of calcium-dependent protease (CDP II)inAllomyces arbuscula

Spatial and cellular localization of calcium-dependent protease (CDP II)inAllomyces arbuscula

Apical Branching in a Temperature Sensitive Mutant ofAspergillus niger

Polarisome Meets Spitzenkörper: Microscopy, Genetics, and Genomics Converge

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