Faculty Opinions recommendation of Septins are important for cell polarity, septation and asexual spore formation in Neurospora crassa and show different patterns of localisation at germ tube tips.

2016 ◽  
Author(s):  
Meritxell Riquelme
Keyword(s):  
Neurospora Crassa ◽  
Cell Polarity ◽  
Germ Tube ◽  
Spore Formation ◽  
Asexual Spore

CHARACTERISTICS OF DEVELOPING ASCI OF NEUROSPORA CRASSA

1965 ◽  
Vol 43 (8) ◽  
pp. 933-938
Author(s):  
Mary B. Mitchell
Keyword(s):  
Neurospora Crassa ◽  
Spore Formation ◽  
Immature Fruit ◽  
Nuclear Behavior ◽  
Nuclear Cycle

Morphology of the ascus and of the ascus cluster, as observed in carmine-stained, squash preparations of the contents of immature fruit bodies, is described with the aid of photomicrographs. Complications which raise questions regarding the applicability of the currently accepted scheme of ascus development are discussed. The function of the crozier, the mechanism of spore formation, and the correlation of nuclear behavior with ascus growth appear to have been misunderstood. It is concluded that the initial stages of ascus development involve complexities, the resolution of which may reveal unknown aspects of the nuclear cycle.

scholarly journals Label-Free Quantitative Proteomics of Lysine Acetylome Identifies Substrates of Gcn5 in Magnaporthe oryzae Autophagy and Epigenetic Regulation

mSystems ◽  
2018 ◽  
Vol 3 (6) ◽  
Author(s):  
Meiling Liang ◽  
Shulin Zhang ◽  
Lihong Dong ◽  
Yanjun Kou ◽  
Chaoxiang Lin ◽  
...  
Keyword(s):  
Epigenetic Regulation ◽  
Magnaporthe Oryzae ◽  
Posttranslational Modification ◽  
Rice Blast ◽  
Histone Acetyltransferase ◽  
Rice Blast Fungus ◽  
Spore Formation ◽  
Content Type ◽  
Autophagy Induction ◽  
Asexual Spore

ABSTRACT The rice blast fungus Magnaporthe oryzae poses a great threat to global food security. During its conidiation (asexual spore formation) and appressorium (infecting structure) formation, autophagy is induced, serving glycogen breakdown or programmed cell death function, both essential for M. oryzae pathogenicity. Recently, we identified an M. oryzae histone acetyltransferase (HAT) Gcn5 as a key regulator in phototropic induction of autophagy and asexual spore formation while serving a cellular function other than autophagy induction during M. oryzae infection. To further understand the regulatory mechanism of Gcn5 on M. oryzae pathogenicity, we set out to identify more Gcn5 substrates by comparative acetylome between the wild-type (WT) and GCN5 overexpression (OX) mutant and between OX mutant and GCN5 deletion (knockout [KO]) mutant. Our results showed that Gcn5 regulates autophagy induction and other important aspects of fungal pathogenicity, including energy metabolism, stress response, cell toxicity and death, likely via both epigenetic regulation (histone acetylation) and posttranslational modification (nonhistone protein acetylation). IMPORTANCE Gcn5 is a histone acetyltransferase that was previously shown to regulate phototropic and starvation-induced autophagy in the rice blast fungus Magnaporthe oryzae, likely via modification on autophagy protein Atg7. In this study, we identified more potential substrates of Gcn5-mediated acetylation by quantitative and comparative acetylome analyses. By epifluorescence microscopy and biochemistry experiments, we verified that Gcn5 may regulate autophagy induction at both the epigenetic and posttranslational levels and regulate autophagic degradation of a critical metabolic enzyme pyruvate kinase (Pk) likely via acetylation. Overall, our findings reveal comprehensive posttranslational modification executed by Gcn5, in response to various external stimuli, to synergistically promote cellular differentiation in a fungal pathogen.

Ascospore germination, growth in culture, and imperfect spore formation in Cookeina sulcipes and Phillipsia crispata

1975 ◽  
Vol 53 (1) ◽  
pp. 56-61 ◽  
Author(s):  
J. W. Paden
Keyword(s):  
Germ Tube ◽  
Outer Wall ◽  
Wall Layer ◽  
Spore Formation ◽  
Spore Surface ◽  
No Formation ◽  
Ascospore Germination ◽  
Germ Tubes

Ascospores of Cookeina sulcipes germinate by one of two modes: (1) by the production of blastoconidia on sympodially proliferating conidiogenous cells which may arise from any point on the spore surface, and (2) by a thick polar germ tube. No ascospores were seen to germinate both ways. The conidiogenous cells are occasionally modified into narrow hyphae. The blastoconidia germinate readily but are evidently very short-lived. Ascospores of Phillipsia crispata germinate by two polar germ tubes; there is no formation of blastoconidia. In both species the inner ascospore wall separated from an outer wall layer during germination. In culture both C. sulcipes and P. crispata form arthroconidia. The arthroconidia are uninucleate; they germinate readily and reproduce the species when transferred to fresh plates.

ENZYME ACTIVITIES DURING THE ASEXUAL CYCLE OF NEUROSPORA CRASSA: I. SUCCINIC DEHYDROGENASE

1967 ◽  
Vol 13 (9) ◽  
pp. 1203-1210 ◽  
Author(s):  
G. J. Stine
Keyword(s):  
Neurospora Crassa ◽  
Enzyme Activities ◽  
Soluble Protein ◽  
Mycelial Growth ◽  
Germ Tube ◽  
Succinic Dehydrogenase ◽  
Growth Yield ◽  
Conidial Germination ◽  
Germination And Growth ◽  
Asexual Cycle

Separate extracts of Neuorospora crassa grown either in Vogel's medium N, medium N + glutamate, or medium N which had been made deficient in zinc, were assayed for succinic dehydrogenase and soluble protein at intervals throughout the asexual cycle. Succinic dehydrogenase, although apparently unnecessary for either the formation of conidia or conidial germination, does appear to be necessary for mycelial growth and for the production of conidiophores. Differences in the amount of enzyme during morphologically distinct states of differentiation (i.e. production of the germ tube and production of the conidiophore) may serve as an indicator of significant changes in the physiology of Neurospora at these times during development.The level of succinic dehydrogenase in the conidiophore before its differentiation into conidia appears to influence the amount of this enzyme found in the conidia. This is in keeping with the idea that conditions prevailing in the cytoplasm before the formation of conidia may directly influence the constituents subsequently found in the conidia which determine conidial viability, rate of germination, and growth yield.

Aktive Aufnahme von Zuckern durch Zellen von Neurospora crassa unter Beteiligung eines enzymatischen Systems mit Permease-Eigenschaften II

1967 ◽  
Vol 22 (2) ◽  
pp. 188-195 ◽  
Author(s):  
Walter Klingmüller
Keyword(s):  
Neurospora Crassa ◽  
Germ Tube ◽  
Dry Weight ◽  
Tube Length ◽  
Enzymatic System ◽  
Aqueous Extracts ◽  
Millipore Filter ◽  
Base Level ◽  
Germ Tube Length ◽  
Insoluble Form

Sorbose-transport in Neurospora has been investigated further. Methods and results were as follows:Conidia pregerminated with fructose were incubated with increasing amounts of 14C-labelled sorbose, their radioactivity was measured by millipore-filter technique. Sorbose uptake followed Michaelis-Menten kinetics, with Km = 5.1 ± 1.2 mM and Vmax=0.16 ± 0.05 mg sorbose/mg dry weight/minute. It was inhibited slightly by addition of fructose, and strongly by addition of glucose; the exact type of inhibition was concentration dependent.Ungerminated conidia or pregerminated conidia were incubated with 14C-labelled sorbose. A base level of sorbose uptake by ungerminated conidia, and an increasing uptake with increasing pregermination time of the conidia was found; the uptake was proportional to germ-tube length.Supernatants of ungerminated or germinated conidia were checked for sugars related to sorbose by enzymatic and bio-assays. The results were negative.Radiopaperchromatography of aqueous extracts of incubated conidia revealed that sorbose as opposed to fructose is not phosphorylated during uptake, but accumulated as the pure sugar inside the cells. Ca. 90% of the fructose but barely 7% of sorbose taken up is transformed into a water insoluble form after 60 minutes incubation of the conidia.Conidia incubated with labelled sorbose were treated with unlabelled sorbose or Na-azide. The accumulated labelled sorbose was driven out by both treatments (with sorbose ca. 65% with Naazide ca. 80% after 60 minutes).The data support the hypothesis proposed earlier1 that sorbose is taken up into conidia of Neurospora crassa by means of active transport, mediated by an inducible enzymatic system of the permease-type.

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

2013 ◽  
Vol 12 (8) ◽  
pp. 1097-1105 ◽  
Author(s):  
Rosa A. Fajardo-Somera ◽  
Barry Bowman ◽  
Meritxell Riquelme
Keyword(s):  
Plasma Membrane ◽  
Neurospora Crassa ◽  
Nutrient Uptake ◽  
Laser Scanning ◽  
Germ Tube ◽  
Secretory Pathway ◽  
Fluorescent Protein ◽  
Fungal Growth ◽  
Electrochemical Gradient ◽  
Content Type

ABSTRACT Most 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 μm) and in completely developed septa, but not at the tip, indicative of a distinct secretory route independent of the Spitzenkörper occurring behind the apex.

scholarly journals ENZYME ACTIVITIES DURING THE ASEXUAL CYCLE OF NEUROSPORA CRASSA

1968 ◽  
Vol 37 (1) ◽  
pp. 81-88 ◽  
Author(s):  
G. J. Stine
Keyword(s):  
Neurospora Crassa ◽  
Mycelial Growth ◽  
Germ Tube ◽  
Enzyme Synthesis ◽  
Nicotinamide Adenine ◽  
Glutamic Dehydrogenase ◽  
Specific Activities ◽  
Early Phases ◽  
Asexual Cycle ◽  
Logarithmic Growth

Three enzymes, (a) nicotinamide adenine diphosphate-dependent glutamic dehydrogenase (NAD enzyme), (b) nictoinamide adenine triphosphate-dependent glutamic dehydrogenase (NADP enzyme), and (c) nicotinamide-adenine dinucleotidase (NADase), were measured in separate extracts of Neurospora crassa grown in Vogel's medium N and medium N + glutamate. Specific activities and total units per culture of each enzyme were determined at nine separate intervals phased throughout the asexual cycle. The separate dehydrogenases were lowest in the conidia, increased slowly during germination, and increased rapidly during logarithmic mycelial growth. The amounts of these enzymes present during germination were small when compared with those found later during the production of the conidiophores. The NAD enzyme may be necessary for pregermination synthesis. The NADP-enzyme synthesis was associated with the appearance of the germ tube. Although higher levels of the dehydrogenases in the conidiophores resulted in more enzyme being found in the differentiated conidia, the rate of germination was uneffected. The greatest activity for the NADase enzyme was associated with the conidia, early phases of germination, and later production of new conidia. NADase decreased significantly with the onset of logarithmic growth, remained low during the differentiation of conidiophores, and increased considerably as the conidiophores aged.

Ultrastructural studies of primary spores of Conidiobolus, Erynia, and related Entomophthorales

1989 ◽  
Vol 67 (9) ◽  
pp. 2576-2589 ◽  
Author(s):  
J. P. Latgé ◽  
D. F. Perry ◽  
M. C. Prévost ◽  
R. A. Samson
Keyword(s):  
Outer Layer ◽  
Germ Tube ◽  
Spore Wall ◽  
Wall Layer ◽  
Spore Formation ◽  
Dense Layer ◽  
Nuclear Ultrastructure ◽  
Ultrastructural Studies ◽  
Thin Electron ◽  
Definition Of

Wall development during primary spore formation, discharge, and germination of Entomophthorales is emphasized in ultrastructural studies of Conidiobolus, Entomophaga, Neozygites, and Erynia. In the fungi examined, spore and sporophore walls consist of a thick, electron-translucent inner layer and a thin, electron-dense outer layer. During spore formation, cytoplasm of the supporting sporophore cell migrates into the spore initial. As the former cell empties, a septum develops. Discharge is caused by inversion of the papillum, which lacks the electron-dense layer. Only in Erynia did the two spore wall layers separate upon impact. Intracytoplasmic organization of the primary spore is typical of the Zygomycotina; the morphology of organelles was characteristic of species, whereas nuclear ultrastructure was consistent within genera. Conidiobolus nuclei have a prominent nucleolus that lacks heterochromatin, in contrast with the other genera where large patches of heterochromatin were observed. Upon germination, no rupture of the spore outer layer was observed other than at points of germ tube emergence. The germ tube wall was continuous with the inner spore wall layer. The results are discussed in reference to Entomophthorales taxonomy and definition of the terms conidium and monosporous sporangiolum.

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