Transhyphal Electrical Currents in Fungi

Abstract

Representative mycelial fungi from the phycomycete, ascomycete and basidiomycete groups ( Achlya bisexualis, Neurospora crassa, Aspergillus nidulans, Schizophyllum commune and Coprinus cinereus) all generated steady electrical currents around their hyphal tips; the generation of a transhyphal ion current may therefore be a universal characteristic of hyphal growth. As with all other tip growing organisms, positive current always entered apically and left distally; nongrowing hyphae did not drive transcellular currents. The current density, measured approximately 30 pm from the membrane surface at the hyphal tips, varied between 0.05 and 0.60 pA cm-2 in different fungi and tended to be larger in wider, rapidly extending hyphae than in thinner, slow growing hyphae. The possibility that these currents serve to localize growth at the apex is discussed.

Confocal ratio imaging of cytoplasmic pH during germ tube growth and appressorium induction by Magnaporthe grisea

“…The transcellular currents were suggested to influence cell activity by processes such as those involving the electrophoresis of vesicles and\or membrane proteins, by the gating of voltage-sensitive ion channels or by influencing the polymerization and depolymerization of the cytoskeleton. Additionally, an analysis of external pH (pH e ) with pH-sensitive microelectrodes showed that there was a depletion of protons around the tips of growing hyphae of Achlya bisexualis (Gow, 1984) and N. crassa (Takeuchi et al, 1988). Indirect evidence for the involvement of pH c in fungal morphogenesis was obtained from studies on the electrical fields associated with developing cells and especially from tipgrowing cells, around which these electrical fields were found to be very prominent (reviewed by Gow, 1989).…”

“…More controversial is the existence of gradients in cytoplasmic pH (pH c ). Although there is good circumstantial evidence for the existence of gradients in cytoplasmic H + concentration in tip-growing cells (Slayman, 1965a,b ;Slayman & Slayman, 1974 ;Gow, 1984 ; *Present address : Institute of Virology, University of Veterinary Sciences, Veterina$ rplatz 1, Josef-Baumann-Gasse, A-1210 Wien, Austria (tel 43 1 25077 2334 ; fax 43 1 25077 2390 ; e-mail Till.Jelitto!Vu-Wien.ac.at) Takeuchi et al, 1988), direct measurements of pH c provided contradictory results, as discussed by Parton et al (1997).…”

Influence of applied electrical fields on yeast and hyphal growth of Candida albicans

“…0001-5776 C) 1990 SGM opposed to electrical current) and the ability of the hypha to extend (Gow et al, 1984).…”

“…Growing fungal hyphae normally generate an electrical current so that positive charge enters the hyphal tip and exits from the rear (Gow, 1984;Harold etal., 1985;Gow, 1989a, 6). A great deal of effort has been spent in trying to establish the functional relationship between the morphological and electrical polarity of these cells (Gow, 1989b).…”

Transcellular ionic currents studied by intracellular potential recordings in Neurospora crassa hyphae Transfer of energy from proximal to apical cells

“…Sci. USSR, Moscow 117071, USSR polarized extension of the N. crassa hyphae were observed using a vibrating probe and pH sensitive microelectrodes [5,6]. To account for the above data it hsa been proposed that the apical cells of the hyphae were relatively deficient in H+-ATPase [6,7].…”