1887

Abstract

Fungal cells maintain an internal hydrostatic pressure (turgor) of about 400–500 kPa. In the filamentous fungus , the initial cellular responses to hyperosmotic treatment are loss of turgor, a decrease in relative hyphal volume per unit length (within 1 min) and cell growth arrest; all recover over a period of 10–60 min due to increased net ion uptake and glycerol production. The electrical responses to hyperosmotic treatment are a transient depolarization of the potential (within 1 min), followed by a sustained hyperpolarization (after 4 min) to a potential more negative than the initial potential (a driving force for ion uptake). The nature of the transient depolarization was explored in the context of other transient responses to hyperosmotic shock, to determine whether activation of a specific ion permeability or some other rapid change in electrogenic transport was responsible. Changing the ionic composition of the extracellular medium revealed that K permeability increases and H permeability declines during the transient depolarization. We suggest that these changes are due to concerted inhibition of the electrogenic H-ATPase, and an increase in a K conductance. Knockout mutants of known K (, , , ) and Cl (a homologue) channels and transporters had no effect on the transient depolarization, but and do play a role in osmoadaptation, as does a homologue of a serine kinase regulator of H-ATPase in yeast, Ptk2.

Keyword(s): BTP, Bistris propane
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2009-03-01
2020-07-08
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References

  1. Alex L. A., Borkovich K. A., Simon M. I.. 1996; Hyphal development in Neurospora crassa: involvement of a two-component histidine kinase. Proc Natl Acad Sci U S A93:3416–3421
    [Google Scholar]
  2. Bartnicki-Garcia S., Bracker C. E., Gierz G., Lopez-Franco R., Lu H.. 2000; Mapping the growth of fungal hyphae: orthogonal cell wall expansion during tip growth and the role of turgor. Biophys J79:2382–2390
    [Google Scholar]
  3. Beever R. E., Laracy E. P.. 1986; Osmotic adjustment in the filamentous fungus Aspergillus nidulans. J Bacteriol168:1358–1365
    [Google Scholar]
  4. Bohnert H. T., Jensen R. G.. 1996; Strategies for engineering water-stress tolerance in plants. Trends Biotechnol14:89–97
    [Google Scholar]
  5. Colot H. V., Park G., Turner G. E., Ringelberg C., Crew C. M., Litvinkova L., Weiss R. L., Borkovich K. A., Dunlap J. C.. 2006; A high through-put gene knockout procedure for Neurospora reveals functions for multiple transcription factors. Proc Natl Acad Sci U S A103:10352–10357
    [Google Scholar]
  6. Davis R. H., de Serres F. J.. 1970; Genetic and microbiological research techniques for Neurospora crassa. Methods Enzymol17A:79–143
    [Google Scholar]
  7. Ellis S. W., Grindle M., Lewis D. H.. 1991; Effect of osmotic stress on yield and polyol content of dicarboximide-sensitive and -resistant strains of Neurospora crassa. Mycol Res95:457–464
    [Google Scholar]
  8. Eraso P., Mazon M. J., Portillo F.. 2006; Yeast protein kinase Ptk2 localizes at the plasma membrane and phosphorylates in vitro the C-terminal peptide of the H+-ATPase. Biochim Biophys Acta 1758;164–170
    [Google Scholar]
  9. Fujimura M., Ochiai N., Oshima M., Motoyama T., Ichiishi A., Usami R., Horikoshi K., Yamaguchi I.. 2003; Putative homologs of SSK22 MAPKK kinase and PBS2 MAPK kinase of Saccharomyces cerevisiae encoded by os-4 and os-5 genes for osmotic sensitivity and fungicide resistance in Neurospora crassa. Biosci Biotechnol Biochem67:186–191
    [Google Scholar]
  10. Haro R., Sainz L., Rubio F., Rodriguez-Navarro A.. 1999; Cloning of two genes encoding potassium transporters in Neurospora crassa and expression of the corresponding cDNAs in Saccharomyces cerevisiae. Mol Microbiol31:511–520
    [Google Scholar]
  11. Husken D., Steudle E., Zimmerman U.. 1978; Pressure probe technique for measuring water relations of cells in higher plants. Plant Physiol61:158–163
    [Google Scholar]
  12. Jennings D. H.. 1995; The Physiology of Fungal Nutrition pp398–446 Cambridge, UK: Cambridge University Press;
    [Google Scholar]
  13. Jones C. A., Greer-Philips S. E., Borkovich K. A.. 2007; The response regulator RRG-1 functions upstream of a mitogen-activated protein kinase pathway impacting asexual development, female fertility, osmotic stress, and fungicide resistance in Neurospora crassa. Mol Biol Cell18:2123–2136
    [Google Scholar]
  14. Kaminskyj S. G. W., Garrill A., Heath I. B.. 1992; The relation between turgor and tip growth in Saprolegnia ferax: turgor is necessary, but not sufficient to explain apical extension rates. Exp Mycol16:64–75
    [Google Scholar]
  15. Kiranmayi P., Mohan P. M.. 2006; Metal transportome of Neurospora crassa. In Silico Biol6:169–180
    [Google Scholar]
  16. Krantz M., Becit E., Hoffmann S.. 2006; Comparative genomics of the HOG-signaling system in fungi. Curr Genet49:137–151
    [Google Scholar]
  17. Lew R. R.. 1996; Pressure regulation of the electrical properties of growing Arabidopsis thaliana L. roothairs. Plant Physiol112:1089–1100
    [Google Scholar]
  18. Lew R. R.. 2005; Mass flow and pressure-driven hyphal extension in Neurospora crassa. Microbiology151:2685–2692
    [Google Scholar]
  19. Lew R. R.. 2007; Ionic currents and ion fluxes in Neurospora crassa hyphae. J Exp Bot58:3475–3481
    [Google Scholar]
  20. Lew R. R., Levina N. N.. 2007; Turgor regulation in the osmosensitive cut mutant of Neurospora crassa. Microbiology153:1530–1537
    [Google Scholar]
  21. Lew R. R., Levina N. N., Walker S. K., Garrill A.. 2004; Turgor regulation of hyphal organisms. Fungal Genet Biol41:1007–1015
    [Google Scholar]
  22. Lew R. R., Levina N. N., Shabala L., Anderca M. I., Shabala S. N.. 2006; Role of a mitogen-activated protein kinase cascade in ion flux-mediated turgor regulation in fungi. Eukaryot Cell5:480–487
    [Google Scholar]
  23. Lew R. R., Abbas Z., Anderca M. I., Free S. J.. 2008; Phenotype of a mechanosensitive channel mutant, mid-1, in a filamentous fungus, Neurospora crassa. Eukaryot Cell7:647–655
    [Google Scholar]
  24. McCluskey K.. 2003; The Fungal Genetics Stock Center: from molds to molecules. Adv Appl Microbiol52:245–262
    [Google Scholar]
  25. Miller T. K., Renault S., Selitrennikoff C. P.. 2002; Molecular dissection of alleles of the osmotic-1 locus of Neurospora crassa. Fungal Genet Biol35:147–155
    [Google Scholar]
  26. Money N. P., Harold F. M.. 1993; Two water molds can grow without measurable turgor pressure. Planta190:426–430
    [Google Scholar]
  27. Noguchi R., Banno S., Ichikawa R., Fukumori F., Ichiishi A., Kimura M., Yamaguchi I., Fujimura M.. 2007; Identification of OS-2 MAP kinase-dependent genes induced in response to osmotic stress, antifungal agent fludioxinil, and heat shock in Neurospora crassa. Fungal Genet Biol44:208–218
    [Google Scholar]
  28. O'Rourke S. M., Herskowitz I., O'Shea E. K.. 2002; Yeast go the whole HOG for the hyperosmotic response. Trends Genet18:405–412
    [Google Scholar]
  29. Philip J. R.. 1958; The osmotic cell, solute permeability, and the plant water economy. Plant Physiol33:264–271
    [Google Scholar]
  30. Roberts S. K.. 2003; TOK homologue in Neurospora crassa: first cloning and functional characterization of an ion channel in a filamentous fungus. Eukaryot Cell2:181–190
    [Google Scholar]
  31. Slayman C. L.. 1965; Electrical properties of Neurospora crassa. Effects of external cations on the intracellular potential. J Gen Physiol49:69–92
    [Google Scholar]
  32. Slayman C. L., Long W. S., Lu C. Y.. 1973; The relationship between ATP and electrogenic pump in the plasma membrane of Neurospora crassa. J Membr Biol14:305–338
    [Google Scholar]
  33. Vogel H. J.. 1956; A convenient growth medium for Neurospora. Microb Genet Bull13:42–46
    [Google Scholar]
  34. Zhang Y., Lamm R., Pillonel C., Lam S., Xu J.-R.. 2002; Osmoregulation and fungicide resistance: The Neurospora crassa os-2 gene encodes a HOG1 mitogen-activated protein kinase homologue. Appl Environ Microbiol68:532–538
    [Google Scholar]
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