Skip to main content
NCBI home page
Proceedings of the National Academy of Sciences of the United States of America logoLink to Proceedings of the National Academy of Sciences of the United States of America
. 1988 Mar;85(5):1534–1538. doi: 10.1073/pnas.85.5.1534

Transcellular proton current in Achlya bisexualis hyphae: relationship to polarized growth.

W J Schreurs 1, F M Harold 1
PMCID: PMC279807  PMID: 2894029

Abstract

Growing hyphae of Achlya bisexualis drive an electric current through themselves, such that positive charge flows into the apical region (the anterior 300 micron) and exits distally along the hyphal trunk. They also generate a gradient of extracellular pH, such that the medium surrounding the apex is slightly alkaline whereas that along the hyphal trunk is acid. To explore the genesis of these gradients and their relationship to polarized extension, we examined the effects of changes in the composition of the growth medium. The transcellular electric current was most pronounced in medium rich in amino acids. In leaner medium, containing limited amounts of amino acids or none at all, the current was attenuated or absent. We interpret the results to mean that inward current represents H+/amino acid symport, mediated by porters that are preferentially localized in the apical region. Apical alkalinity may be due to ammonia production. Outward current, and perhaps also the generation of metabolic acid, reflects the distribution of the H+-ATPase, which is excluded from the apex but is abundant along the hyphal trunk. Thanks to the spatial segregation of transport functions, protons characteristically flow into the apical region. However, since hyphae grow apically and at the same rate despite wide variations in current pattern, the flow of electric charge through the hyphae cannot be required to polarize extension or to localize the tip.

Full text

PDF
1534

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Ammann D., Lanter F., Steiner R. A., Schulthess P., Shijo Y., Simon W. Neutral carrier based hydrogen ion selective microelectrode for extra- and intracellular studies. Anal Chem. 1981 Dec;53(14):2267–2269. doi: 10.1021/ac00237a031. [DOI] [PubMed] [Google Scholar]
  2. Blatt M. R., Slayman C. L. Role of "active" potassium transport in the regulation of cytoplasmic pH by nonanimal cells. Proc Natl Acad Sci U S A. 1987 May;84(9):2737–2741. doi: 10.1073/pnas.84.9.2737. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Busa W. B. Mechanisms and consequences of pH-mediated cell regulation. Annu Rev Physiol. 1986;48:389–402. doi: 10.1146/annurev.ph.48.030186.002133. [DOI] [PubMed] [Google Scholar]
  4. Eddy A. A. Mechanisms of solute transport in selected eukaryotic micro-organisms. Adv Microb Physiol. 1982;23:1-78, 269-70. doi: 10.1016/s0065-2911(08)60335-5. [DOI] [PubMed] [Google Scholar]
  5. Goffeau A., Slayman C. W. The proton-translocating ATPase of the fungal plasma membrane. Biochim Biophys Acta. 1981 Dec 30;639(3-4):197–223. doi: 10.1016/0304-4173(81)90010-0. [DOI] [PubMed] [Google Scholar]
  6. Gow N. A., Kropf D. L., Harold F. M. Growing hyphae of Achlya bisexualis generate a longitudinal pH gradient in the surrounding medium. J Gen Microbiol. 1984 Nov;130(11):2967–2974. doi: 10.1099/00221287-130-11-2967. [DOI] [PubMed] [Google Scholar]
  7. Harold R. L., Harold F. M. Ionophores and cytochalasins modulate branching in Achlya bisexualis. J Gen Microbiol. 1986 Jan;132(1):213–219. doi: 10.1099/00221287-132-1-213. [DOI] [PubMed] [Google Scholar]
  8. Hill T. W., Mullins J. T. Hyphal tip growth in Achlya. I. Cytoplasmic organization. Can J Microbiol. 1980 Sep;26(9):1132–1140. doi: 10.1139/m80-187. [DOI] [PubMed] [Google Scholar]
  9. Jaffe L. F., Nuccitelli R. An ultrasensitive vibrating probe for measuring steady extracellular currents. J Cell Biol. 1974 Nov;63(2 Pt 1):614–628. doi: 10.1083/jcb.63.2.614. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Jaffe L. F., Nuccitelli R. Electrical controls of development. Annu Rev Biophys Bioeng. 1977;6:445–476. doi: 10.1146/annurev.bb.06.060177.002305. [DOI] [PubMed] [Google Scholar]
  11. Jaffe L. F. The role of ionic currents in establishing developmental pattern. Philos Trans R Soc Lond B Biol Sci. 1981 Oct 7;295(1078):553–566. doi: 10.1098/rstb.1981.0160. [DOI] [PubMed] [Google Scholar]
  12. Kropf D. L., Caldwell J. H., Gow N. A., Harold F. M. Transcellular ion currents in the water mold Achlya. Amino acid proton symport as a mechanism of current entry. J Cell Biol. 1984 Aug;99(2):486–496. doi: 10.1083/jcb.99.2.486. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Kropf D. L. Electrophysiological properties of Achlya hyphae: ionic currents studied by intracellular potential recording. J Cell Biol. 1986 Apr;102(4):1209–1216. doi: 10.1083/jcb.102.4.1209. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Kropf D. L., Harold F. M. Selective transport of nutrients via the rhizoids of the water mold Blastocladiella emersonii. J Bacteriol. 1982 Jul;151(1):429–437. doi: 10.1128/jb.151.1.429-437.1982. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Kropf D. L., Lupa M. D., Caldwell J. H., Harold F. M. Cell polarity: endogenous ion currents precede and predict branching in the water mold achyla. Science. 1983 Jun 24;220(4604):1385–1387. doi: 10.1126/science.220.4604.1385. [DOI] [PubMed] [Google Scholar]
  16. Sanders D., Hansen U. P., Slayman C. L. Role of the plasma membrane proton pump in pH regulation in non-animal cells. Proc Natl Acad Sci U S A. 1981 Sep;78(9):5903–5907. doi: 10.1073/pnas.78.9.5903. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from Proceedings of the National Academy of Sciences of the United States of America are provided here courtesy of National Academy of Sciences

RESOURCES