Control of Extension of the Hyphal Apex

Gow, Neil A. R.

doi:10.1007/978-1-4612-3624-5_6

Cited by 23 publications

(9 citation statements)

References 118 publications

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“…After releasing their contents, the membranes of the vesicles contribute to the extension of the plasma membrane at the hyphal tip. Endocytotic traffic may counterbalance a possible increase of membrane surface and maintain an appropriate size and protein and lipid content of the plasma membrane (Gow, 1989). Although endocytotic traffic can occur by several independent pathways (Riezman, 1997), a direct proof of endocytosis is difficult.…”

Section: Academic Pressmentioning

confidence: 99%

Endocytosis and Membrane Turnover in the Germ Tube ofUromyces fabae

Hoffmann

Mendgen

1998

Fungal Genetics and Biology

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Hoffmann, J. and Mendgen, K. 1998. Endocytosis and membrane turnover in the germ tube of Uromyces fabae. Fungal Genetics and Biology 24, 77-85. We have used the fluorescent dye FM4-64 as a tracer to demonstrate bulk membrane internalization (endocytosis) and redistribution of the dye within the cytoplasm of the germ tube of the rust fungus Uromyces fabae. Staining of the hyphal membrane was detected 4 s after application of FM4-64 and reached a maximum after 1 min. The highest fluorescence intensity occurred in the apex. Subsequently, staining of the plasma membrane decreased and a subapical region of the fungal protoplast (5-20 m from the tip) displayed increasing fluorescence with a maximum after 5 min. Fluorescence in the subapical region was redistributed to an area in the hyphal tip, which corresponds to the accumulation of apical vesicles, after 10-15 min and subsequently to a cytoplasmic region in front of the two nuclei (35-45 m from the tip). We conclude from our measurements of membrane fluorescence that the turnover time from endocytosis to secretion of the dye amounts to 15 min. The uptake of the dye into the cytoplasm, but not membrane loading, could be inhibited completely with 5 mM NaN 3 or by a temperature shift to 4°C. This is the first evidence for endocytosis in a fungal germ tube. Academic PressIndex Descriptors: tip growth; hyphal apex; Spitzenkö rper; apical vesicle cluster.

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Section: Academic Pressmentioning

confidence: 99%

Endocytosis and Membrane Turnover in the Germ Tube ofUromyces fabae

Hoffmann

Mendgen

1998

Fungal Genetics and Biology

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“…The spatial arrangement of cytoskeletal elements during growth is consistent with their proposed involvement in cell morphogenesis. Mts are considered to be primarily responsible for the long distance transport of secretory vesicles to the Spk, while actin microfilaments are principally involved in their short distance transport from the Spk to the plasma membrane, as well as maintaining and controlling vesicle organization and dynamics within the Spk (Gooday, 1983;Gow, 1989;Harris et al, 2005;Hasek and Bartnicki-Garcia, 1994;Heath, 1994;Howard, 1981;Howard andAist, 1977, 1980;McDaniel and Roberson, 1998;Roberson and Fuller, 1988). Accordingly, the Spk may be viewed as a switching station from Mt to microfilament-based vesicle transport.…”

Section: Introductionmentioning

confidence: 98%

Microtubule dynamics and organization during hyphal growth and branching in Neurospora crassa

Mouriño-Pérez

Roberson

Bartnicki-García

2006

Fungal Genetics and Biology

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“…Our previous work with microtubule inhibitors implicated the microtubular cytoskeleton in the positioning and movement of the Spk in hyphae of N. crassa (Riquelme et al, 1998), but its exact role in apical growth has yet to be elucidated. It has long been proposed that cytoplasmic microtubules participate in the transport of secretory vesicles to the hyphal apex (Howard & Aist, 1977, 1980Howard, 1981 ;Gooday, 1983 ;Gow, 1989 ;Hasek & Bartnicki-Garcı! a, 1994 ;McKerracher & Heath, 1987 ;Heath, 1994).…”

Section: Introductionmentioning

confidence: 99%

Dynein and dynactin deficiencies affect the formation and function of the Spitzenkörper and distort hyphal morphogenesis of Neurospora crassa

2000

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The impact of mutations affecting microtubule-associated motor proteins on the morphology and cytology of hyphae of Neurospora crassa was studied. Two ropy mutants, ro-1 and ro-3, deficient in dynein and dynactin, respectively, were examined by video-enhanced phase-contrast microscopy and image analysis. In contrast to the regular, hyphoid morphology of wildtype hyphae, the hyphae of the ropy mutants exhibited a great variety of distorted, non-hyphoid morphologies. The ropy hyphae were slow-growing and manifested frequent loss of growth directionality. Cytoplasmic appearance, including organelle distribution and movement, were ostensibly different in the ropy hyphae. The Spitzenko $ rper (Spk) of wild-type hyphae was readily seen by phase-contrast optics ; the Spk of both ro-1 and ro-3 was less prominent and sometimes undetectable. Only the fast-growing ropy hyphae displayed a Spk, and it was smaller and less phase-dark than the wild-type Spk. Growth rate in both wild-type and ropy mutants was directly correlated with the size of the Spk. Spk efficiency, measured in terms of cell area generated per Spk travelled distance, was lower in ropy mutants. Another salient difference between ropy mutants and wild-type hyphae was in Spk trajectory. Whereas the Spk of wild-type hyphae maintained a trajectory close to the cell growth axis, the Spk of ropy hyphae moved much more erratically. Sustained departures in the trajectory of the ropy Spk produced corresponding distortions in hyphal morphology. A causal correlation between Spk trajectory and cell shape was tested with the Fungus Simulator program. The characteristic morphologies of wild-type or ropy hyphae were reproduced by the Fungus Simulator, whose vesicle supply centre (VSC) was programmed to follow the corresponding Spk trajectories. This is evidence that the Spk controls hyphal morphology by operating as a VSC. These findings on dynein or dynactin deficiency support the notion that the microtubular cytoskeleton plays a major role in the formation and positioning of the Spk, with dramatic consequences on hyphal growth and morphogenesis.

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Control of Extension of the Hyphal Apex

Cited by 23 publications

References 118 publications

Endocytosis and Membrane Turnover in the Germ Tube ofUromyces fabae

Endocytosis and Membrane Turnover in the Germ Tube ofUromyces fabae

Microtubule dynamics and organization during hyphal growth and branching in Neurospora crassa

Dynein and dynactin deficiencies affect the formation and function of the Spitzenkörper and distort hyphal morphogenesis of Neurospora crassa

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