Journal Article

Acidification and Alkalinization of Culture Medium by Catharanthus roseus cells¯Is Anoxic Production of Lactate a Cause of Cytoplasmic Acidification?

Katsuhiro Sakano, Seiichiro Kiyota and Yoshiaki Yazaki

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 38, issue 9, pages 1053-1059
Published in print January 1997 | ISSN: 0032-0781
Published online January 1997 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/oxfordjournals.pcp.a029271
Acidification and Alkalinization of Culture Medium by Catharanthus roseus cells¯Is Anoxic Production of Lactate a Cause of Cytoplasmic Acidification?

More Like This

Show all results sharing these subjects:

  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry

GO

Show Summary Details

Preview

Catharanthus roseus(L.) G. Don cells acidified Mura-shige-Skoog medium rapidly. Upon transfer to fresh medium, the medium pH (initially5.3) dropped below 4 within 2 d. This acidification was reversed under hypoxic conditions. The cells induced a similar acidification in a simple medium consisting of CaCl2, KCl, and glucose: medium pH dropped below 4 within 6 h. The acidification was accompanied by an influx of K+ at a H+(efflux)/K+ ratio of ca 0.6 as well as by an expansion of endogenous organic acid pool, in which malic and citric acids were the major components. Anoxia reversed all these processes: the direction of both K+ and H+ fluxes reversed with a H+/K+ ratio of 1.70. Anoxia induced a cytoplasmic acidification from pH 7.6 (aerobic) to 7.4 as measured by 31P-NMR, accompanied by a rapid, long-lasting lactate accumulation at expense of malic and citric acids. Evidence suggested that accumulation of lactic acid was not a cause of cytoplasmic acidification under anoxia, but a result of pH regulation by the biochemical pH-stat [Davies (1973) Symp. Soc. Exp. Biol. 27: 513]. The anoxic acidification of the cytoplasm was ascribed to the influx of H+ from the medium.

Keywords: Anoxia; Biochemical pH-stat; Biophysical pH-stat; Medium acidification; Organic acid metabolism; 31P-NMR

Journal Article.  0 words. 

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

Full text: subscription required

How to subscribe Recommend to my Librarian

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.