Ontogeny of the Spitzenkörper in germlings of Neurospora crassa

Araujo-Palomares, Cynthia L.; Castro-Longoria, Ernestina; Riquelme, Meritxell

doi:10.1016/j.fgb.2006.10.004

Cited by 49 publications

(45 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…At the same time, this approach provides a convenient method to alleviate potential problems based on the presumed overexpression of fusion proteins under the control of the ccg-1 promoter (Fig. 1B and D and 2C and D) (4,20,24).…”

Section: Resultsmentioning

confidence: 99%

“…Within this exclusion zone, the phase-dark Spitzenkörper, a vesicle-dominated complex intimately involved in hyphal tip growth, forms. The development of the mature Spitzenkörper was suggested previously to represent the transition from germ tube to vegetative hypha (4).…”

mentioning

confidence: 92%

“…The cytology of germ tube development in N. crassa has been analyzed in detail in living cells (4). Macroconidia and germlings undergo isotropic growth during the first 2 h following hydration in minimal growth medium at 25°C.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Nuclear Dynamics, Mitosis, and the Cytoskeleton during the Early Stages of Colony Initiation in Neurospora crassa

et al. 2010

View full text Add to dashboard Cite

Neurospora crassa macroconidia form germ tubes that are involved in colony establishment and conidial anastomosis tubes (CATs) that fuse to form interconnected networks of conidial germlings. Nuclear and cytoskeletal behaviors were analyzed in macroconidia, germ tubes, and CATs in strains that expressed fluorescently labeled proteins. Heterokaryons formed by CAT fusion provided a rapid method for the imaging of multiple labeled fusion proteins and minimized the potential risk of overexpression artifacts. Mitosis occurred more slowly in nongerminated macroconidia (1.0 to 1.5 h) than in germ tubes (16 to 20 min). The nucleoporin SON-1 was not released from the nuclear envelope during mitosis, which suggests that N. crassa exhibits a form of "closed mitosis." During CAT homing, nuclei did not enter CATs, and mitosis was arrested. Benomyl treatment showed that CAT induction, homing, fusion, as well as nuclear migration through fused CATs do not require microtubules or mitosis. Three ropy mutants (ro-1, ro-3, and ro-11) defective in the dynein/dynactin microtubule motor were impaired in nuclear positioning, but nuclei still migrated through fused CATs. Latrunculin B treatment, imaging of F-actin in living cells using Lifeact-red fluorescent protein (RFP), and analysis of mutants defective in the Arp2/3 complex demonstrated that actin plays important roles in CAT fusion.

show abstract

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 92%

See 1 more Smart Citation

Nuclear Dynamics, Mitosis, and the Cytoskeleton during the Early Stages of Colony Initiation in Neurospora crassa

et al. 2010

View full text Add to dashboard Cite

show abstract

“…PMA-1-GFP was practically absent at the apex of the PM of germlings. The distribution of PMA-1-GFP was analyzed during the different germination phases, previously established (36,37): phase I, conidia during hydration; phase II, germ tube emergence; phase III, germ tube elongation, and phase IV, mature hyphae. In nongerminated conidia growing isotropically during phase I, PMA-1-GFP fluorescence was evenly distributed throughout the PM (Fig.…”

Section: Selection Of Strains Expressing Pma-1-gfpmentioning

confidence: 99%

The Plasma Membrane Proton Pump PMA-1 Is Incorporated into Distal Parts of the Hyphae Independently of the Spitzenkörper in Neurospora crassa

2013

Self Cite

View full text Add to dashboard Cite

bMost models for fungal growth have proposed a directional traffic of secretory vesicles to the hyphal apex, where they temporarily aggregate at the Spitzenkörper before they fuse with the plasma membrane (PM). The PM H ؉ -translocating ATPase (PMA-1) is delivered via the classical secretory pathway (endoplasmic reticulum [ER] to Golgi) to the cell surface, where it pumps H ؉ out of the cell, generating a large electrochemical gradient that supplies energy to H ؉ -coupled nutrient uptake systems. To characterize the traffic and delivery of PMA-1 during hyphal elongation, we have analyzed by laser scanning confocal microscopy (LSCM) strains of Neurospora crassa expressing green fluorescent protein (GFP)-tagged versions of the protein. In conidia, PMA-1-GFP was evenly distributed at the PM. During germination and germ tube elongation, PMA-1-GFP was found all around the conidial PM and extended to the germ tube PM, but fluorescence was less intense or almost absent at the tip. Together, the data indicate that the electrochemical gradient driving apical nutrient uptake is generated from early developmental stages. In mature hyphae, PMA-1-GFP localized at the PM at distal regions (>120 m) and in completely developed septa, but not at the tip, indicative of a distinct secretory route independent of the Spitzenkörper occurring behind the apex. One of the main features of filamentous fungi is their apical mode of growth. In filamentous fungi, cell wall growth and exocytosis are linked processes that involve the highly polarized traffic of cell wall-building secretory vesicles to apical areas, where they deliver proteins and lipids. One of the most widely accepted models for fungal growth, the vesicle supply center for fungal morphogenesis, postulates a unidirectional traffic of vesicles to the hyphal apex, where they aggregate temporarily at an apical structure, the Spitzenkörper, prior to fusion with the apical plasma membrane (PM) by the process of exocytosis (1). However, some PM proteins, such as the H ϩ -ATPases, essential for hyphal growth, have been previously predicted to be absent or inactive at the hyphal apex (2-4), suggesting the existence of vesicle delivery routes other than the above and independent of the Spitzenkörper that reach nonapical regions of the hyphal PM. H ϩ -ATPases are involved in pumping protons out of the cell, generating a large electrochemical gradient and supplying energy to H ϩ -coupled nutrient uptake systems (5). This electrochemical gradient has been studied in several fungal species by diverse methods, including vibrating probes, microelectrodes, and pH indicators. The results showed that current normally flows inward at the hyphal apical regions and flows outward at distal areas (3, 4, 6-9).PMA1, the H ϩ -ATPase-encoding gene in Saccharomyces cerevisiae (SCRG_01016 [10]), has a single homolog in Neurospora crassa (NCU01680 [11,12]). In S. cerevisiae, Pma1p is one of the most abundant proteins of the cell surface (25 to 50%), while in N. crassa, it constitutes about 5 to 10% of the...

show abstract

“…A similar structure, however, has so far not been recognized in germ tube tips of Neurospora that are less than 150 mm in length (Araujo-Palomares et al, 2007) or in CATs , raising the question as to how directional changes during germ tube avoidance and CAT homing are realized in the absence of a Spitzenkörper. Thus, our third hypothesis is that activated GTPases are central components of a plasma-membrane-associated cortical vesicle supply center that organizes targeted secretion during directional tip growth of germ tubes and CATs in response to chemotropic cues.…”

Section: Introductionmentioning

confidence: 96%

CDC-42 and RAC-1 regulate opposite chemotropisms inNeurospora crassa

Lichius

Goryachev

Fricker

et al. 2014

Journal of Cell Science

Self Cite

View full text Add to dashboard Cite

Cell polarization and fusion are crucial developmental processes that occur in response to intracellular and extracellular signals. Asexual spores (conidia) of the mold Neurospora crassa differentiate two types of polarized cell protrusions, germ tubes and conidial anastomosis tubes (CATs), which exhibit negative and positive chemotropism, respectively. We provide the first evidence that shared and separate functions of the Rho-type GTPases CDC-42 and RAC-1 regulate these opposite chemotropisms. We demonstrate that RAC-1 is essential for CAT formation and cell fusion, whereas CDC-42 is necessary and sufficient for normal germ tube development. Cdc42-Rac-interactive-binding (CRIB) reporters were constructed to exclusively label locally activated GTP-bound GTPases. Time course analyses showed that repositioning of these activated GTPase clusters within germ tube and CAT tip apices controls directional growth in the absence of a tip-localized vesicle supply center (Spitzenkö rper). We propose a model in which the local assembly of a plasma-membraneassociated GTPase-PAK-MAPK signaling platform regulates chemoattractant perception and secretion in order to synchronize oscillatory cell-cell communication and directional CAT tip growth.

show abstract

Ontogeny of the Spitzenkörper in germlings of Neurospora crassa

Cited by 49 publications

References 37 publications

Nuclear Dynamics, Mitosis, and the Cytoskeleton during the Early Stages of Colony Initiation in Neurospora crassa

Nuclear Dynamics, Mitosis, and the Cytoskeleton during the Early Stages of Colony Initiation in Neurospora crassa

The Plasma Membrane Proton Pump PMA-1 Is Incorporated into Distal Parts of the Hyphae Independently of the Spitzenkörper in Neurospora crassa

CDC-42 and RAC-1 regulate opposite chemotropisms inNeurospora crassa

Contact Info

Product

Resources

About