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Browner D, Adamatzky A. Micro-electrode array recording of extracellular electrical potentials of liquid static surface fermented Hericium erinaceus. Biosystems 2024:105298. [PMID: 39159880 DOI: 10.1016/j.biosystems.2024.105298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2024] [Revised: 08/06/2024] [Accepted: 08/11/2024] [Indexed: 08/21/2024]
Abstract
Hericium erinaceus is a Basidiomycetes fungus with previously uncharacterised extracellular electrophysiology. Here, we present results of recordings of the electrical potentials of fungal biofilms of this species using microelectrode arrays (MEAs). In particular, we focused on modelling the temporal and spatial progression of the low frequency (≤ 1 Hz) potentials. Culture media control studies showed that the electrical potential activity results from the growth and subsequent spiking behaviours of the mycelium extracellular matrices. An antifungal assay using nystatin suspension, 10,000 unit/mL in DPBS, provided evidence for the biological origin of electrical potentials due to targeting of the selective permeability of the cell membrane and subsequent cessation of electrical activity. Conversely, injection of L-glutamic acid increased the combined multi-channel mean firing rate from 0.04 Hz to 0.1 Hz. Analysis of bursting and spatial propagation of the extracellular signals are also presented.
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Potapova TV. Structural and functional organization of growing tips of Neurospora crassa Hyphae. BIOCHEMISTRY (MOSCOW) 2014; 79:593-607. [PMID: 25108323 DOI: 10.1134/s0006297914070025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Data are presented on a variety of intracellular structures of the vegetative hyphae of the filamentous fungus Neurospora crassa and the involvement of these structures in the tip growth of the hyphae. Current ideas on the molecular and genetic mechanisms of tip growth and regulation of this process are considered. On the basis of comparison of data on behaviors of mitochondria and microtubules and data on the electrical heterogeneity of the hyphal apex, a hypothesis is proposed about a possible supervisory role of the longitudinal electric field in the structural and functional organization of growing tips of the N. crassa hyphae.
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Affiliation(s)
- T V Potapova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia.
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3
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The plasma membrane proton pump PMA-1 is incorporated into distal parts of the hyphae independently of the Spitzenkörper in Neurospora crassa. EUKARYOTIC CELL 2013; 12:1097-105. [PMID: 23729384 DOI: 10.1128/ec.00328-12] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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.
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Zivanović BD. Surface tip-to-base Ca2+ and H+ ionic fluxes are involved in apical growth and graviperception of the Phycomyces stage I sporangiophore. PLANTA 2012; 236:1817-1829. [PMID: 22910875 DOI: 10.1007/s00425-012-1738-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Accepted: 08/03/2012] [Indexed: 06/01/2023]
Abstract
Net fluxes of Ca(2+) and H(+) ions were measured non-invasively close to the surface of Phycomyces blakesleeanus sporangiophores stage I using ion-selective vibrating microelectrodes. The measurements were performed on a wild type (Wt) and a gravitropic mutant A909 kept in either vertical or tilted orientation. Microelectrodes were positioned 4 μm from the surface of sporangiophore, and ion fluxes were recorded from the apical (0-20 μm) and subapical (50-100 μm) regions. The magnitude and direction of ionic fluxes measured were dependent on the distance from the tip along the growing zone of sporangiophore. Vertically oriented sporangiophores displayed characteristic tip-to-base ion fluxes patterns. Ca(2+) and H(+) fluxes recorded from apical region of Wt sporangiophores were inward-directed, while ion fluxes from subapical locations occurred in both directions. In contrast to Wt, mutant A909 showed opposite (outward) direction of Ca(2+) fluxes and reduced H(+) influxes in the apical region. Following gravistimulation, the magnitude and direction of ionic fluxes were altered. Wt sporangiophore exhibited oppositely directed fluxes on the lower (influx) and the upper (efflux) sides of the cell, while mutant A909 did not show such patterns. A variable elongation growth in vertical position and reduced growth rate upon gravistimulation were observed in both strains. The data show that tip-growing sporangiophores exhibit a tip-to-base ion flux pattern which changes characteristically upon gravistimulation in Wt in contrast to the mutant A909 with a strongly reduced gravitropic response.
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Affiliation(s)
- Branka D Zivanović
- Department for Life Sciences, Institute for Multidisciplinary Research, University of Belgrade, Kneza Višeslava 1, 11030, Belgrade, Serbia.
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Lew RR. How does a hypha grow? The biophysics of pressurized growth in fungi. Nat Rev Microbiol 2011; 9:509-18. [DOI: 10.1038/nrmicro2591] [Citation(s) in RCA: 163] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Z˘ivanovic B, Köhler K, Galland P, Weisenseel M. MEMBRANE POTENTIAL AND ENDOGENOUS ION CURRENT OFPHYCOMYCESSPORANGIOPHORES. ACTA ACUST UNITED AC 2009. [DOI: 10.1081/jbc-100108575] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Alcántara-Sánchez F, Reynaga-Peña CG, Salcedo-Hernández R, Ruiz-Herrera J. Possible role of ionic gradients in the apical growth of Neurospora crassa. Antonie van Leeuwenhoek 2004; 86:301-11. [PMID: 15702382 DOI: 10.1007/s10482-004-0101-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The effects of the Ca2+/H+ exchanger A23187 and the K+/H+ exchanger nigericin on the growth of Neurospora crassa were analyzed. Both ionophores had the same effects on the fungus. They both inhibited growth in liquid media, apical extension being more affected than protein synthesis. A sudden challenge to either ionophore on solid media rapidly stopped hyphal extension. Additionally, both ionophores induced profuse mycelium branching and upward hyphal growth. Hyphae growing on nigericin-containing media also burst at the apex. Both ionophores caused a rapid inhibition in the apically-occurring synthesis of structural wall polysaccharides, but they did not affect mitochondrial energy conservation. With the use of DiBAC, a membrane-potential sensitive fluorophore, it was excluded that their effects were due to depletion of the plasma membrane potential. Considering that both ionophores exchange H+ for different metallic ions, we concluded that their effect was due to dissipation of a proton gradient, which is directly or indirectly involved in the apical growth of the fungus.
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Affiliation(s)
- Felipe Alcántara-Sánchez
- Departamento de Ingeniería Genética, Unidad Irapuato, Centro de Investigación y de Estudios Avanzados del IPN, Irapuato Gto., México
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Torralba S, Heath IB, Ottensmeyer FP. Ca(2+) shuttling in vesicles during tip growth in Neurospora crassa. Fungal Genet Biol 2001; 33:181-93. [PMID: 11495575 DOI: 10.1006/fgbi.2001.1282] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Tip-growing organisms maintain an apparently essential tip-high gradient of cytoplasmic Ca(2+). In the oomycete Saprolegnia ferax, in pollen tubes and root hairs, the gradient is produced by a tip-localized Ca(2+) influx from the external medium. Such a gradient is normally dispensable for Neurospora crassa hyphae, which may maintain their Ca(2+) gradient by some form of internal recycling. We localized Ca(2+) in N. crassa hyphae at the ultrastructural level using two techniques (a) electron spectroscopic imaging of freeze-dried hyphae and (b) pyroantimoniate precipitation. The results of both methods support the presence of Ca(2+) in the wall vesicles and Golgi body equivalents, providing a plausible mechanism for the generation and maintenance of the gradient by Ca(2+) shuttling in vesicles to the apex, without exogenous Ca(2+) influx. Ca(2+) sequestration into the vesicles seems to be dependent on Ca(2+)-ATPases since cyclopiazonic acid, a specific inhibitor of Ca(2+) pumps, eliminated all Ca(2+) deposits from the vesicles of N. crassa.
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Affiliation(s)
- S Torralba
- Department of Biology, York University, Toronto, Ontario, M3J 1P3, Canada
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Valdez-Taubas J, Diallinas G, Scazzocchio C, Rosa AL. Protein expression and subcellular localization of the general purine transporter UapC from Aspergillus nidulans. Fungal Genet Biol 2000; 30:105-13. [PMID: 11017766 DOI: 10.1006/fgbi.2000.1197] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The uapC gene of Aspergillus nidulans belongs to a family of nucleobase-specific transporters conserved in prokaryotic and eucaryotic organisms. We report the use of immunological and green fluorescent protein based strategies to study protein expression and subcellular distribution of UapC. A chimeric protein containing a plant-adapted green fluorescent protein (sGFP) fused to the C-terminus of UapC was shown to be functional in vivo, as it complements a triple mutant (i.e., uapC(-) uapA(-) azgA(-)) unable to grow on uric acid as the sole nitrogen source. UapC-GFP is located in the plasma membrane and, secondarily, in internal structures observed as fluorescent dots. A strong correlation was found between cellular levels of UapC-GFP fluorescence and known patterns of uapC gene expression. This work represents the first in vivo study of protein expression and subcellular localization of a filamentous fungal nucleobase transporter.
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Affiliation(s)
- J Valdez-Taubas
- Departamento de Química Biológica (CIQUIBIC-CONICET), Universidad de Nacional de Córdoba, Argentina
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Lew RR. Comparative analysis of Ca2+ and H+ flux magnitude and location along growing hyphae of Saprolegnia ferax and Neurospora crassa. Eur J Cell Biol 1999; 78:892-902. [PMID: 10669108 DOI: 10.1016/s0171-9335(99)80091-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Calcium and proton ion fluxes were mapped at the growing apices of two hyphal organisms, the oomycete Saprolegnia ferax and the ascomycete Neurospora crassa and pseudohyphal Saccharomyces cerevisiae using self-referencing ion-selective probes. S. ferax exhibited well-defined transport zones absent in N. crassa. Ca2+ fluxes were located within 8 microm of the growing hyphal tip; the net Ca2+ flux was either inward (75% of all experiments) or outward. The inward component of the net flux was inhibited by Gd3+, known to inhibit Ca2+ permeable stretch-activated channels. Because the Ca2+ flux is located at the region of maximal hyphal expansion, exocytosis may contribute to Ca2+ efflux, in addition to the stretch-activated channel mediated influx. Maximal inward H+ flux was observed 10-30 microm behind the hyphal tip where peak mitochondria densities taper off at the onset of a vacuolation zone, presumably due to highly localized H+ cotransporter activity. By contrast, N. crassa exhibited no net Ca2+ flux and a consistently inward H+ flux (93% of all experiments) that was homogeneously distributed up to 60 microm behind the hyphal apex. Both hyphal organisms have similar tip morphology and growth rates, and are reported to have tip-high cytosolic Ca2+ gradients associated with growth. Only S. ferax exhibited tip-localized Ca2+ fluxes and a well defined H+ influx zone just behind the tip. Differences in ecological habitats and cytology--S. ferax is an aquatic organism that grows as a migrating plug of cytoplasm while N. crassa is normally terrestrial with a cytoplasm-rich mycelium and highly active cytoplasmic streaming behind the growing margin--may account for the differences in the 'architecture' of ion transport occurring during the process of tip growth. Net Ca2+ efflux and H+ influx of growing S. cerevisiae pseudohyphae were also measured but localization was not possible due to small cell size.
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Affiliation(s)
- R R Lew
- Department of Biology, York University, Toronto, Ontario, Canada.
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Abstract
Ion channel mapping techniques are described and the results for two fungal organisms, Saprolegnia ferax and Neurospora crassa, are presented. In these species, two channel types have been characterized, stretch-activated channels exhibiting significant calcium permeability and spontaneous channels having significant potassium permeability. Two distinct analyses of patch clamp data, analysis of channel self-clustering and association between different channel types, and localization along the hyphae, reveal significant differences between the two organisms. S. ferax maintains a tip-high gradient of both channel types which is lost after disruption of the actin cytoskeleton. There is significant self-clustering of the channels, as well as interactions between channel types. N. crassa on the other hand does not maintain tip-high gradients, and clustered distributions are observed only for the stretch-activated channels. In terms of physiological roles, evidence is quite strong that the stretch-activated channels function as a growth sensor in S. ferax, but have an unknown function in N. crassa. In both organisms, the potassium permeable channels presumably function in potassium uptake. The differences between these two organisms may be due, in part, to differences in their normal environment: aquatic versus terrestrial. Copyright 1998 Academic Press.
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Affiliation(s)
- RR Lew
- Department of Biology, York University, 4700 Keele Street, Toronto, Ontario, M3J 1P3, Canada
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Sipiczki M, Takeo K, Yamaguchi M, Yoshida S, Miklos I. Environmentally controlled dimorphic cycle in a fission yeast. MICROBIOLOGY (READING, ENGLAND) 1998; 144 ( Pt 5):1319-1330. [PMID: 9611807 DOI: 10.1099/00221287-144-5-1319] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The fission yeast Schizosaccharomyces pombe shows bipolar growth and is a convenient model for studying cell polarity and polar growth. This paper shows that the related Schiz. japonicus var. japonicus can switch to unipolar growth and can exist in both yeast and mycelial phases. On solid media, the yeast phase is unstable and prone to switch to the mycelial form, which shows unipolar growth by tip elongation. The hyphae can colonize the body of the substrate (true mycelium) or just its surface (pseudo-mycelium). The yeast-to-mycelium transition and the growth of the mycelium are regulated by a nutritional gradient and are associated with extensive vacuolation. The mycelium can convert into arthroconidia or return to the yeast phase in response to environmental changes. These environmentally controlled morphological transitions make Schiz. japonicus var. japonicus an attractive model for the investigation of cell polarity and morphogenesis.
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Affiliation(s)
- M Sipiczki
- Department of GeneticsP.O. Box 56, H-4010 Debrecen, Hungary
- Division of Ultrastructure and Function, Research Center for Pathogenic Fungi and Microbial Toxicoses, Chiba University, Chiba, Japan
- Institute of Biology University of Debrecen, P.O. Box 56, H-4010 Debrecen, Hungary
| | - K Takeo
- Division of Ultrastructure and Function, Research Center for Pathogenic Fungi and Microbial Toxicoses, Chiba University, Chiba, Japan
| | - M Yamaguchi
- Division of Ultrastructure and Function, Research Center for Pathogenic Fungi and Microbial Toxicoses, Chiba University, Chiba, Japan
| | - S Yoshida
- Division of Ultrastructure and Function, Research Center for Pathogenic Fungi and Microbial Toxicoses, Chiba University, Chiba, Japan
| | - I Miklos
- Department of GeneticsP.O. Box 56, H-4010 Debrecen, Hungary
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Burgstaller W. Transport of small lons and molecules through the plasma membrane of filamentous fungi. Crit Rev Microbiol 1997; 23:1-46. [PMID: 9097013 DOI: 10.3109/10408419709115129] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Less than 1% of the estimated number of fungal species have been investigated concerning the transport of low-molecular-weight nutrients and metabolites through the plasma membrane. This is surprising if one considers the importance of the processes at the plasma membrane for the cell: this membrane mediates between the cell and its environment. Concentrating on filamentous fungi, in this review emphasis is placed on relating results from biophysical chemistry, membrane transport, fungal physiology, and fungal ecology. Among the treated subjects are the consequences of the small dimension of hyphae, the habitat and membrane transport, the properties of the plasma membrane, the efflux of metabolites, and the regulation of membrane transport. Special attention is given to methodological problems occurring with filamentous fungi. A great part of the presented material relies on work with Neurospora crassa, because for this fungus the most complete picture of plasma membrane transport exists. Following the conviction that we need "concepts instead of experiments", we delineate the lively network of membrane transport systems rather than listing the properties of single transport systems.
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Cairney JWG, Burke RM. Physiological heterogeneity within fungal mycelia: an important concept for a functional understanding of the ectomycorrhizal symbiosis. THE NEW PHYTOLOGIST 1996; 134:685-695. [PMID: 33863201 DOI: 10.1111/j.1469-8137.1996.tb04934.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Individual mycelia of filamentous fungi display considerable heterogeneity at the physiological level. Important physiological processes such as nutrient absorption, extracellular enzyme secretion and solute translocation occur differentially within an individual mycelium, and vary according to spatio-temporal changes in patterns of gene expression as the mycelium develops and senesces. In ectomycorrhizal (ECM) fungi, gene expression appears to be strongly influenced by interaction with the soil environment and the host root. The ECM mycelium is thus a complex and dynamic entity wherein discrete regions display particular physiological attributes. Physiological heterogeneity is important in the overall functioning of the symbiosis. In the particular case of movement of phosphorus from soil to host root in the ECM symbiosis, heterogeneity might provide the driving force for the integrated processes of absorption, translocation and transfer. It is suggested that it is only by considering the sum of the seemingly disparate physiological processes within the heterogeneous mycelium that mycorrhizal functioning can be fully understood.
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Affiliation(s)
- J W G Cairney
- Department of Biological Sciences, University of Western Sydney (Nepean), PO Box 10, Kingswood, NSW 2747, Australia
| | - R M Burke
- Department of Biochemistry & Applied Molecular Biology, UMIST, PO Box 88, Manchester M60 1QD, UK
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Kropf DL, Gibbon BC, Money NP. Role of cytosolic pH in axis establishment and tip growth. ACTA ACUST UNITED AC 1995. [DOI: 10.1139/b95-235] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The role of cytosolic pH (pHc) in determining the growth site and in tip elongation has been investigated by measuring and manipulating pHc. pHcacidifies by 0.1–0.2 units as the growth axis is established. Concomitantly, cells accumulate KCl, which increases the cellular osmotic pressure, resulting in the generation of turgor pressure. The K+taken up is apparently compartmentalized as the free cytosolic K+activity remains constant. At present, the relation between pHc, K+, and turgor pressure is not well understood. A small but statistically significant cytosolic pH gradient, acid at the future growth site, is also detectable during axis establishment. As growth is initiated the intensity of the gradient increases to approximately 0.3 pH units. The magnitude of the pH gradient correlates with the rate of tip elongation. The gradient may regulate tip elongation in a number of ways, including local control of the assembly and stability of cytoskeletal elements. Key words: cytosolic pH gradients, tip growth, turgor pressure, weak acids and bases, SNARF 1, pH-sensitive microelectrodes.
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Levina NN, Lew RR, Hyde GJ, Heath IB. The roles of Ca2+ and plasma membrane ion channels in hyphal tip growth of Neurospora crassa. J Cell Sci 1995; 108 ( Pt 11):3405-17. [PMID: 8586653 DOI: 10.1242/jcs.108.11.3405] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Growing hyphae of the ascomycete fungus Neurospora crassa contained a tip-high gradient of cytoplasmic Ca2+, which was absent in non-growing hyphae and was insensitive to Gd3+ in the medium. Patch clamp recordings in the cell-attached mode, from the plasma membrane of these hyphae, showed two types of channel activities; spontaneous and stretch activated. The spontaneous channels were identified as inward K+ channels based on inhibition by tetraethylammonium. The stretch activated channels had increased amplitudes in response to elevated Ca2+ in the pipette solution, and thus are permeable to Ca2+ and mediate inward Ca2+ movement. Gd3+, which is an inhibitor of some stretch activated channels, incompletely inhibited stretch activated channel activity. Both tetraethylammonium and Gd3+ only transiently reduced the rates of tip growth without changing tip morphology, thus indicating that the channels are not absolutely essential for tip growth. Furthermore, in contrast to the hyphae of another tip growing organism, Saprolegnia ferax, tip-high gradients of neither spontaneous nor stretch activated channels were found. Voltage clamping of the apical plasma membrane potential in the range from -300 to +150 mV did not affect the rates of hyphal elongation. Collectively, these data suggest that ion transport across the plasma membrane at the growing tip in Neurospora is not obligatory for the maintenance of tip growth, but that a gradient of Ca2+, possibly generated from internal stores in an unknown way, is required.
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Affiliation(s)
- N N Levina
- Biology Department, York University, North York, Ontario, Canada
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Abstract
The presence of a cytosolic pH gradient and its relation to polar tip growth was investigated in rhizoid cells of Pelvetia embryos with the use of pH-sensitive microelectrodes and by ratio imaging. Growing rhizoid cells generated a longitudinal pH gradient in which the apical cytosol was 0.3 to 0.5 units more acidic than the cytosol at the base of the cell. Treatment with a membrane-permeant weak acid, propionic acid, dissipated the cytosolic pH gradient and inhibited growth. The magnitude of the pH gradient correlated well with the rate of tip elongation. The pH gradient spatially superimposed on the cytosolic calcium gradient, and inhibition of calcium fluxes by treatment with lanthanum abolished the pH gradient and inhibited growth.
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Roncal T, Ugalde UO, Irastorza A. Calcium-induced conidiation in Penicillium cyclopium: calcium triggers cytosolic alkalinization at the hyphal tip. J Bacteriol 1993; 175:879-86. [PMID: 8380805 PMCID: PMC196236 DOI: 10.1128/jb.175.3.879-886.1993] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Addition of Ca2+ (1 to 10 mM) to submerged cultures of Penicillium cyclopium induces conidiation. Ca2+ induced an increase in cytosolic pH from approximately 7.00 to > 7.60 in less than 10 min, as determined with the fluorescent pH probe fluorescein. Measurement of the H(+)-ATPase activity in total membrane fractions did not show any stable activation in vivo as a result of Ca2+ treatment. By fluorescence ratio imaging microscopy, it was observed that vegetative hyphae exhibit a tip-to-base pH gradient, with the tip being more acidic. Ca2+ caused this gradient to dissipate within 10 min. The effect of several agents that are supposed to cause internal acidification, by different means, on conidiation was tested. Concentrations of these agents that did not significantly affect growth but inhibited Ca(2+)-induced conidiation also prevented the intracellular alkalinization observed after exposure to the cation. Calcium channel blockers (lanthanum, cobalt, verapamil, and nifedipine) were not able to inhibit Ca(2+)-induced conidiation, although their effect on calcium uptake was not evaluated. However, the combined results point towards externally bound Ca2+ as the primary agent of conidiation induction, causing changes in plasma membrane function which disrupt the pH gradient observed during apical growth.
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Affiliation(s)
- T Roncal
- Departamento de Química Aplicada, Facultad de Ciencias Químicas, Universiad del País Vasco, San Sebastián, Spain
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Inwardly directed ionic currents of Allomyces macrogynus and other water moulds indicate sites of proton-driven nutrient transport but are incidental to tip growth. ACTA ACUST UNITED AC 1992. [DOI: 10.1016/s0953-7562(09)80591-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Leger R, Roberts D, Staples R. A model to explain differentiation of appressoria by germlings of Metarhizium anisopliae. J Invertebr Pathol 1991. [DOI: 10.1016/0022-2011(91)90134-c] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Cho CW, Harold FM, Schreurs WJ. Electric and ionic dimensions of apical growth inAchlya hyphae. ACTA ACUST UNITED AC 1991. [DOI: 10.1016/0147-5975(91)90005-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Abstract
We recognize organisms first and foremost by their forms, but how they grow and shape themselves still largely passes understanding. The objective of this article is to survey what has been learned of morphogenesis of walled eucaryotic microorganisms as a set of problems in cellular heredity, biochemistry, physiology, and organization. Despite the diversity of microbial forms and habits, some common principles can be discerned. (i) That the form of each organism represents the expression of a genetic program is almost universally taken for granted. However, reflection on the findings with morphologically aberrant mutants suggests that the metaphor of a genetic program is misleading. Cellular form is generated by a web of interacting chemical and physical processes, whose every strand is woven of multiple gene products. The relationship between genes and form is indirect and cumulative; therefore, morphogenesis must be addressed as a problem not of molecular genetics but of cellular physiology. (ii) The shape of walled cells is determined by the manner in which the wall is laid down during growth and development. Turgor pressure commonly, perhaps always, supplies the driving force for surface enlargement. Cells yield to this scalar force by localized, controlled wall synthesis; their forms represent variations on the theme of local compliance with global force. (iii) Growth and division in bacteria display most immediately the interplay of hydrostatic pressure, localized wall synthesis, and structural constraints. Koch's surface stress theory provides a comprehensive and quantitative framework for understanding bacterial shapes. (iv) In the larger and more versatile eucaryotic cells, expansion is mediated by the secretion of vesicles. Secretion and ancillary processes, such as cytoplasmic transport, are spatially organized on the micrometer scale. The diversity of vectorial physiology and of the forms it generates is illustrated by examples: apical growth of fungal hyphae, bud formation in yeasts, germination of fucoid zygotes, and development of cells of Nitella, Closterium, and other unicellular algae. (v) Unicellular organisms, no less than embryos, have a remarkable capacity to impose spatial order upon themselves with or without the help of directional cues. Self-organization is reviewed here from two perspectives: the theoretical exploration of morphogens, gradients, and fields, and experimental study of polarization in Fucus cells, extension of hyphal tips, and pattern formation in ciliates. Here is the heart of the matter, yet self-organization remains nearly as mysterious as it was a century ago, a subject in search of a paradigm.
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Affiliation(s)
- F M Harold
- Department of Biochemistry, Colorado State University, Fort Collins 80523
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25
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Potapova TV, Aslanidi KB, Boitzova LJu. Energy transfer via cell-to-cell junctions. Ouabain-resistant cells maintain a membrane potential in ouabain-sensitive cells. FEBS Lett 1990; 262:69-71. [PMID: 2318313 DOI: 10.1016/0014-5793(90)80156-d] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Animal cell cooperation has been studied in a mixed cell culture. Membrane potentials of human embryonic cells and hamster BHK-21 cells were recorded by intracellular microelectrodes. The Na+/K(+)-ATPase inhibitor ouabain (1 x 10(-6) M; 2 h) caused strong depolarisation of the human cells in pure culture. The same treatment reduced only slightly the membrane potential in the hamster cells in pure or mixed cultures, as well as in the human cells in mixed culture. The above data can be explained by effective ion fluxes through heterotypic gap junctions in mixed culture. Thus, in the presence of ouabain the Na+/K(+)-ATPase of hamster cells creates transmembrane differences of the electrochemical potential of ions not only in the hamster cells, but in the human cells as well.
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Affiliation(s)
- T V Potapova
- A.N. Belozersky Laboratory of Molecular Biology and Bioorganic Chemistry, Moscow State University, USSR
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26
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Bowdan E, Kunkel JG. Patterns of ionic currents around the developing oocyte of the German cockroach, Blattella germanica. Dev Biol 1990; 137:266-75. [PMID: 2303165 DOI: 10.1016/0012-1606(90)90253-f] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The development of patterns of current around vitellogenic oocytes of the cockroach, Blattella germanica, was examined by means of a two-dimensional vibrating probe. Previtellogenic oocytes exhibited small unstable currents. Shortly after vitellogenic uptake began (oocytes 0.6-0.8 mm anterior to posterior) currents were either all inward or all outward at the plane of measurement. A dorsoventral pattern of currents was first observed around oocytes a little larger than 0.8 mm. Current exited dorsally (source) and entered ventrally (sink). In these oocytes source and sink were small, less than half the anterior-posterior length. As oocytes grew, relative sizes of source and sink increased until they extended across the major part of dorsal and ventral surfaces. Many late vitellogenic oocytes had a pattern of dorsal outward current with a bimodal distribution. At the onset of chorionation measured currents were again small, unstable, and exhibited no well-defined pattern. Current density was greatest during midvitellogenesis.
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Affiliation(s)
- E Bowdan
- Department of Zoology, University of Massachusetts, Amherst 01003
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27
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Heath I. The Roles of Actin in Tip Growth of Fungi. ACTA ACUST UNITED AC 1990. [DOI: 10.1016/s0074-7696(08)60672-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
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28
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Affiliation(s)
- N A Gow
- Department of Genetics and Microbiology, Marischal College, University of Aberdeen, U.K
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29
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Bittisnich DJ, Williamson RE. Tip-localised H(+)-fluxes and the applicability of the acid-growth hypothesis to tip-growing cells: Control of chloronemal extension in Funaria hygrometrica by auxin and light. PLANTA 1989; 178:96-102. [PMID: 24212554 DOI: 10.1007/bf00392532] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/1988] [Accepted: 12/12/1988] [Indexed: 06/02/2023]
Abstract
The role of tip-localised H(+) secretion in regulating chloronemal tip growth in the moss Funaria hygrometrica Hedw. was investigated. pH was monitored with pH microelectrodes placed close to the cell surface while the rate of extension growth was manipulated by illumination and by the application of indole-3-acetic acid. Growth stimulations were accompanied by acidification of the external solution; this acidification was most pronounced at the growing tip. The timing and extent of acification external to the tip correlated well with the magnitude and time course of growth stimulations. The maintenance of both growth and H(+) efflux under CO2-free conditions indicated that neither photosynthetic nor respiratory CO2 metabolism were involved. Artificially acidifying the nutrient solution rapidly but transiently stimulated elongation in both white light and darkness. Furthermore, the stimulation of elongation caused by white light was inhibited if the nutrient solution was buffered strongly near neutrality. We conclude that the "acid growth" hypothesis is applicable to tip growth in Funaria and that light and exogenous indole-3-acetic acid act at least in part by stimulating localised H(+)-ion efflux.
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Affiliation(s)
- D J Bittisnich
- Botany Department, Research School of Biological Sciences, Australian National University, G.P.O. Box 4, 2601, Canberra, ACT, Australia
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30
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Potapova TV, Aslanidi KB, Belozerskaya TA, Levina NN. Transcellular ionic currents studied by intracellular potential recordings in Neurospora crassa hyphae. Transfer of energy from proximal to apical cells. FEBS Lett 1988; 241:173-6. [PMID: 2973993 DOI: 10.1016/0014-5793(88)81054-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Membrane potentials, input resistances, and electric coupling in the apical parts of N. crassa growing hyphae were recorded with the aid of intracellular microelectrodes. It was revealed that the apical cells were always depolarized by 10 to 30 mV as compared to the adjacent proximal cells. The septal pore maintained an electrical resistance of 4 to 6 M omega. The calculated values of the endogenous electrical current passing through the septal pore varied between 0.5 and 1 nA. Electrical isolation of the apical cells resulted in their depolarization from 120-150 mV to 40-60 mV, characteristics of the membrane potential value of N. crassa adult hyphae with completely blocked electrogenic pumps. A simultaneous increase in the input resistance value from 15-20 M omega to 40-80 M omega was observed. The above data can be explained assuming that H+-ATPase activity was greatly lowered in the apical cells. Thus in the intact hyphae with electrically coupled cells energy is transferred from the proximal hyphal compartments to the apical ones.
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Affiliation(s)
- T V Potapova
- A.N. Belozersky Laboratory of Molecular Biology and Bioorganic Chemistry, Moscow State University, USSR
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