Evidence of self-inhibition by filamentous fungi accounts for unidirectional hyphal growth in colonies

1998 ◽  
Vol 44 (4) ◽  
pp. 390-393 ◽  
Author(s):  
Edward J Bottone ◽  
Nimesh Nagarsheth ◽  
Kenneth Chiu
Keyword(s):  
Filamentous Fungi ◽  
Membrane Filter ◽  
Hyphal Growth ◽  
Cross Reactivity ◽  
Clear Zone ◽  
Dialysis Tubing ◽  
Directional Growth ◽  
Radial Pattern ◽  
Molecular Weight Cutoff ◽  
Agar Surface

Hyphal growth in filamentous fungi proceeds in an unidirectional radial pattern from a point inoculation. An inhibitor produced, secreted, and absorbed by the advancing hyphae has been speculated to account for directional growth. Working with Mucor and Aspergillus, laboratory evidence is provided for the production of an inhibitor by the advancing hyphae of these filmentous fungi that precludes back growth. Strains of Mucor and Aspergillus inoculated in agar on a 0.45-mm membrane filter placed on agar surfaces grow radially beyond the filter perimeter and onto the agar surface. Removal of the filter pad does not result in hyphal extension back into the clear zone underlying the membrane filter. Inoculation of the clear zone with a fresh Mucor or Aspergillus spore suspension does not result in hyphal growth. Instead, germinating spores show aberrant and aborted hyphae. The fungal inhibitor shows cross-reactivity between Mucor and Aspergillus, is resistant to pronase (10 mg/mL) but not chloroform inactivation, and passes through dialysis tubing with a molecular weight cutoff of 3500.Key words: fungal inhibitor, unidirectional hyphal growth, radial hyphal growth, Mucor, Aspergillus.

Activated carbon as a better habitat for water and wastewater treatment microorganisms

2000 ◽  
Vol 42 (12) ◽  
pp. 149-154 ◽  
Author(s):  
M. Okada ◽  
H. Morinaga ◽  
W. Nishijima
Keyword(s):  
Batch Culture ◽  
Bacterial Growth ◽  
Membrane Filter ◽  
Synthetic Medium ◽  
Dialysis Tubing ◽  
Water And Wastewater Treatment ◽  
Batch Cultures ◽  
K 12 ◽  
Bacterial Yield ◽  
Adsorption Desorption

Effects of PAC on bacterial activity were evaluated by sequencing batch cultures (20 hours each) of E.coli K-12 on synthetic medium containing glucose as a sole carbon source. Four suspended sequencing batch culture systems were operated; CP: cultures supplemented with PAC, CR: cultures with removal of metabolites by PAC at the end of each batch culture, CD: cultures supplemented with PAC in dialysis tubing to separate from E.coli, and CC: cultures without PAC (control). The supernatant of each batch culture was filtered through a membrane filter (0.2 μm) and was mixed with the same volume of fresh medium to be used as the medium for the next batch culture. The sequencing batch cultures were repeated three times for all the systems. The bacterial growth in CC was inhibited with the increase in the number of batch cultures. Although a significant amount of metabolites was accumulated in the 3rd batch culture of CC, little accumulation was noted in the 3rd batch culture of CP. No growth inhibition was noted in CP for all the batch cultures. The little differences in the bacterial yield and metabolite accumulation between CR and CD suggested that adsorption/desorption of metabolites with PAC did not play a major role in bacterial growth. PAC addition may partly stimulate the growth by the removal of growth inhibiting metabolites. However, the fact that CP showed higher yield than CR and CD indicated that the contact between bacteria and PAC plays a significant role in the growth of bacteria.

Dipeptidase PEPDA is required for the conidiation pattern shift in Metarhizium acridum

2021 ◽  
Author(s):  
Juan Li ◽  
Xueling Su ◽  
Yueqing Cao ◽  
Yuxian Xia
Keyword(s):  
Amino Acids ◽  
Filamentous Fungi ◽  
Pathogenic Fungus ◽  
Digital Gene Expression ◽  
Hyphal Growth ◽  
Metarhizium Acridum ◽  
Key Enzyme ◽  
Hydrolysis Of ◽  
Microcycle Conidiation

Filamentous fungi conduct two types of conidiation, typical conidiation from mycelia and microcycle conidiation (MC). Fungal conidiation can shift between the two patterns, which involved a large number of genes in the regulation of this process. In this study, we investigated the role of a dipeptidase gene pepdA in conidiation pattern shift in Metarhizium acridum , which is upregulated in MC pattern compared to typical conidiation. Results showed that disruption of the pepdA resulted in a shift of conidiation pattern from MC to typical conidiation. Metabolomic analyses of amino acids showed that the levels of 19 amino acids significantly changed in Δ pepdA mutant. The defect of MC in Δ pepdA can be rescued when nonpolar amino acids, α-alanine, β-alanine or proline, were added into s ucrose y east extract a gar (SYA) medium. Digital gene expression profiling analysis revealed that PEPDA mediated transcription of sets of genes which were involved in hyphal growth and development, sporulation, cell division, and amino acid metabolism. Our results demonstrated that PEPDA played important roles in the regulation of MC by manipulating the levels of amino acids in M. acridum . IMPORTANCE Conidia, as the asexual propagules in many fungi, are start and end of fungal lifecycle. In entomopathogenic fungi, conidia are the infective form essential for their pathogenicity. Filamentous fungi conduct two types of conidiation, typical conidiation from mycelia and microcycle conidiation. The mechanisms of the shift between the two conidiation patterns remain to be elucidated. In this study, we demonstrated that the dipeptidase PEPDA, a key enzyme from the insect-pathogenic fungus Metarhizium acridum for the hydrolysis of dipeptides, is associated with a shift of conidiation pattern. The conidiation pattern of the Δ pepdA mutant was restored when supplemented with the nonpolar amino acids rather than polar amino acids. Therefore, this report highlights that the dipeptidase PEPDA regulates MC by manipulating the levels of amino acids in M. acridum.

scholarly journals Aspergillus nidulans ArfB Plays a Role in Endocytosis and Polarized Growth

2008 ◽  
Vol 7 (8) ◽  
pp. 1278-1288 ◽  
Author(s):  
Soo Chan Lee ◽  
Sabrina N. Schmidtke ◽  
Lawrence J. Dangott ◽  
Brian D. Shaw
Keyword(s):  
Aspergillus Nidulans ◽  
Filamentous Fungi ◽  
Fluorescent Protein ◽  
Homo Sapiens ◽  
Hyphal Growth ◽  
Life Cycles ◽  
Small Gtpase ◽  
Polarized Growth ◽  
Sequence Alignments ◽  
Green Fluorescent

ABSTRACT Filamentous fungi undergo polarized growth throughout most of their life cycles. The Spitzenkörper is an apical organelle composed primarily of vesicles that is unique to filamentous fungi and is likely to act as a vesicle supply center for tip growth. Vesicle assembly and trafficking are therefore important for hyphal growth. ADP ribosylation factors (Arfs), a group of small GTPase proteins, play an important role in nucleating vesicle assembly. Little is known about the role of Arfs in filamentous hyphal growth. We found that Aspergillus nidulans is predicted to encode six Arf family proteins. Analysis of protein sequence alignments suggests that A. nidulans ArfB shares similarity with ARF6 of Homo sapiens and Arf3p of Saccharomyces cerevisiae. An arfB null allele (arfB disrupted by a transposon [arfB::Tn]) was characterized by extended isotropic growth of germinating conidia followed by cell lysis or multiple, random germ tube emergence, consistent with a failure to establish polarity. The mutant germ tubes and hyphae that do form initially meander abnormally off of the axis of polarity and frequently exhibit dichotomous branching at cell apices, consistent with a defect in polarity maintenance. FM4-64 staining of the arfB::Tn strain revealed that another phenotypic characteristic seen for arfB::Tn is a reduction and delay in endocytosis. ArfB is myristoylated at its N terminus. Green fluorescent protein-tagged ArfB (ArfB::GFP) localizes to the plasma membrane and endomembranes and mutation (ArfBG2A::GFP) of the N-terminal myristoylation motif disperses the protein to the cytoplasm rather than to the membranes. These results demonstrate that ArfB functions in endocytosis to play important roles in polarity establishment during isotropic growth and polarity maintenance during hyphal extension.

scholarly journals A Fungus-Specific Ras Homolog Contributes to the Hyphal Growth and Virulence of Aspergillus fumigatus

2005 ◽  
Vol 4 (12) ◽  
pp. 1982-1989 ◽  
Author(s):  
Jarrod R. Fortwendel ◽  
Wei Zhao ◽  
Ruchi Bhabhra ◽  
Steven Park ◽  
David S. Perlin ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Growth Control ◽  
Biomass Accumulation ◽  
Hyphal Growth ◽  
Pathogenic Fungi ◽  
Total Biomass ◽  
Gene Encoding ◽  
Directional Growth ◽  
Solid Media ◽  
Hyphal Morphology

ABSTRACT The Ras family of GTPase proteins has been shown to control morphogenesis in many organisms, including several species of pathogenic fungi. In a previous study, we identified a gene encoding a fungus-specific Ras subfamily homolog, rasB, in Aspergillus fumigatus. Here we report that deletion of A. fumigatus rasB caused decreased germination and growth rates on solid media but had no effect on total biomass accumulation after 24 h of growth in liquid culture. The ΔrasB mutant had an irregular hyphal morphology characterized by increased branching. Expression of rasBΔ113-135, a mutant transgene lacking the conserved rasB internal amino acid insertion, did not complement the deletion phenotype of delayed growth and germination rates and abnormal hyphal morphology. Virulence of the rasB deletion strain was diminished; mice infected with this strain exhibited ∼65% survival compared to ∼10% with wild-type and reconstituted strains. These data support the hypothesis that rasB homologs, which are highly conserved among fungi that undergo hyphal growth, control signaling modules important to the directional growth of fungal hyphae.

scholarly journals A Chitin Synthase with a Myosin-Like Motor Domain Is Essential for Hyphal Growth, Appressorium Differentiation, and Pathogenicity of the Maize Anthracnose Fungus Colletotrichum graminicola

2007 ◽  
Vol 20 (12) ◽  
pp. 1555-1567 ◽  
Author(s):  
Stefan Werner ◽  
Janyce A. Sugui ◽  
Gero Steinberg ◽  
Holger B. Deising
Keyword(s):  
Cell Wall ◽  
Filamentous Fungi ◽  
Hyphal Growth ◽  
Motor Domain ◽  
Plant Colonization ◽  
Colletotrichum Graminicola ◽  
Wild Type ◽  
Chitin Synthesis ◽  
Cell Wall Biogenesis ◽  
Host Cell Wall

Chitin synthesis contributes to cell wall biogenesis and is essential for invasion of solid substrata and pathogenicity of filamentous fungi. In contrast to yeasts, filamentous fungi contain up to 10 chitin synthases (CHS), which might reflect overlapping functions and indicate their complex lifestyle. Previous studies have shown that a class VI CHS of the maize anthracnose fungus Colletotrichum graminicola is essential for cell wall synthesis of conidia and vegetative hyphae. Here, we report on cloning and characterization of three additional CHS genes, CgChsI, CgChsIII, and CgChsV, encoding class I, III, and V CHS, respectively. All CHS genes are expressed during vegetative and pathogenic development. ΔCgChsI and ΔCgChsIII mutants did not differ significantly from the wild-type isolate with respect to hyphal growth and pathogenicity. In contrast, null mutants in the CgChsV gene, which encodes a CHS with an N-terminal myosin-like motor domain, are strongly impaired in vegetative growth and pathogenicity. Even in osmotically stabilized media, vegetative hyphae of ΔCgChsV mutants exhibited large balloon-like swellings, appressorial walls appeared to disintegrate during maturation, and infection cells were nonfunctional. Surprisingly, ΔCgChsV mutants were able to form dome-shaped hyphopodia that exerted force and showed host cell wall penetration rates comparable with the wild type. However, infection hyphae that formed within the plant cells exhibited severe swellings and were not able to proceed with plant colonization efficiently. Consequently, ΔCgChsV mutants did not develop macroscopically visible anthracnose disease symptoms and, thus, were nonpathogenic.

scholarly journals Functional Analysis of Sterol Transporter Orthologues in the Filamentous Fungus Aspergillus nidulans

2015 ◽  
Vol 14 (9) ◽  
pp. 908-921 ◽  
Author(s):  
Nicole Bühler ◽  
Daisuke Hagiwara ◽  
Norio Takeshita
Keyword(s):  
Plasma Membrane ◽  
Aspergillus Nidulans ◽  
Filamentous Fungi ◽  
Gene Deletion ◽  
Fluorescent Protein ◽  
Fungal Growth ◽  
Hyphal Growth ◽  
Apical Plasma Membrane ◽  
Important Species ◽  
Content Type

ABSTRACT Polarized growth in filamentous fungi needs a continuous supply of proteins and lipids to the growing hyphal tip. One of the important membrane compounds in fungi is ergosterol. At the apical plasma membrane ergosterol accumulations, which are called sterol-rich plasma membrane domains (SRDs). The exact roles and formation mechanism of the SRDs remained unclear, although the importance has been recognized for hyphal growth. Transport of ergosterol to hyphal tips is thought to be important for the organization of the SRDs. Oxysterol binding proteins, which are conserved from yeast to human, are involved in nonvesicular sterol transport. In Saccharomyces cerevisiae seven oxysterol-binding protein homologues (OSH1 to -7) play a role in ergosterol distribution between closely located membranes independent of vesicle transport. We found five homologous genes ( oshA to oshE ) in the filamentous fungi Aspergillus nidulans . The functions of OshA-E were characterized by gene deletion and subcellular localization. Each gene-deletion strain showed characteristic phenotypes and different sensitivities to ergosterol-associated drugs. Green fluorescent protein-tagged Osh proteins showed specific localization in the late Golgi compartments, puncta associated with the endoplasmic reticulum, or diffusely in the cytoplasm. The genes expression and regulation were investigated in a medically important species Aspergillus fumigatus , as well as A. nidulans . Our results suggest that each Osh protein plays a role in ergosterol distribution at distinct sites and contributes to proper fungal growth.

scholarly journals Regulation of Early Events in Hyphal Elongation, Branching and Differentiation of Filamentous Fungi

2000 ◽  
Author(s):  
Martin B. Dickman ◽  
Oded Yarden
Keyword(s):  
Protein Kinase ◽  
Filamentous Fungi ◽  
Plant Pathogen ◽  
Fungal Growth ◽  
Hyphal Growth ◽  
Growth Patterns ◽  
Research Project ◽  
Joint Research ◽  
Joint Research Project ◽  
Functional Features

In filamentous fungi, hyphal elongation, branching and morphogenesis are in many cases the key to successful saprophytic and pathogenic fungal proliferation. The understanding of the fungal morphogenetic response to environmental cues is in its infancy. Studies concerning the regulation of fungal growth and development (some of which have been obtained by the participating collaborators in this project) point to the fact that ser/thr protein kinases and phosphatases are (i) involved in the regulation of such processes and (ii) share common structural and functional features between saprophytes and pathogens. It is our objective to combine a pharmaceutical and a genetic approach in order to identify, characterize and functionally dissect some of the regulatory factors involved in hyphal growth, branching and differentiation. Using an immunohistochemical approach, a ser/thr protein kinase involved in hyphal elongation in both Neurospora crassa and Colletotrichum trifolii has been localized in order to identify the physical arena of regulation of hyphal elongation. The analysis of additional kinases and phosphatases (e.g. Protein kinase C, cAMP-dependent kinase, lipid-activated protein kinase, components of the type 2A protein phosphatase) as well as a RAS-related gene (an additional key participant in signal transduction) has been performed. In order to succeed in advancing the goals of this project, we have taken advantage of available elongation/branching mutants in N. crassa and continuously combined the accumulated information obtained while studying the two systems in order to dissect the elements involved in these processes. The various inhibitors/effectors analyzed can serve as a basis for modification to be used as anti-fungal compounds. Understanding the regulation of hyphal proliferation is a key requirement for identifying novel target points for either curbing fungal growth (as in the case of pathogenesis) or affecting growth patterns in various biotechnological processes. The major objective of our joint project was to advance our understanding of regulation of hyphal growth, especially during early events of fungal germination. Towards achieving this goal, we have coupled the analysis of a genetically tractable organism (N. crassa) with a plant pathogen o economic importance (C. trifolii). As the project progressed we believe that the results obtained have provided a reinforcement to our basic approach which called for combining the two fungal systems for a joint research project. On the one hand, we feel that much of the advance made was possible due to the amenability of N. crassa to genetic manipulations. The relevance of some of the initial findings obtained in Neurospora have been proven to be relevant to the plant pathogen while unique features of the pathogen have been identified in Colletotrichum. Most of the results obtained from this research project have been published. Thus, the main volume of this report is comprised of the relevant publications describing the research and results obtained.

scholarly journals The Aspergillus nidulans Kinesin-3 UncA Motor Moves Vesicles along a Subpopulation of Microtubules

2009 ◽  
Vol 20 (2) ◽  
pp. 673-684 ◽  
Author(s):  
Nadine Zekert ◽  
Reinhard Fischer
Keyword(s):  
Aspergillus Nidulans ◽  
Filamentous Fungi ◽  
Fluorescent Protein ◽  
Hyphal Growth ◽  
Cellular Transport ◽  
Mitotic Spindles ◽  
Cytoplasmic Microtubules ◽  
Conventional Kinesin ◽  
Green Fluorescent ◽  
Vesicle Movement

The extremely polarized growth form of filamentous fungi imposes a huge challenge on the cellular transport machinery, because proteins and lipids required for hyphal extension need to be continuously transported to the growing tip. Recently, it was shown that endocytosis is also important for hyphal growth. Here, we found that the Aspergillus nidulans kinesin-3 motor protein UncA transports vesicles and is required for fast hyphal extension. Most surprisingly, UncA-dependent vesicle movement occurred along a subpopulation of microtubules. Green fluorescent protein (GFP)-labeled UncArigor decorated a single microtubule, which remained intact during mitosis, whereas other cytoplasmic microtubules were depolymerized. Mitotic spindles were not labeled with GFP-UncArigor but reacted with a specific antibody against tyrosinated α-tubulin. Hence, UncA binds preferentially to detyrosinated microtubules. In contrast, kinesin-1 (conventional kinesin) and kinesin-7 (KipA) did not show a preference for certain microtubules. This is the first example for different microtubule subpopulations in filamentous fungi and the first example for the preference of a kinesin-3 motor for detyrosinated microtubules.

Sign in / Sign up

Export Citation Format

Share Document