QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online July 6, 2005
Journal of Experimental Biology 208, 2799-2808 (2005)
Published by The Company of Biologists 2005
doi: 10.1242/jeb.01681

This Article Figures Only Full Text Full Text (PDF) An erratum has been published Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Related articles in JEB Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Covi, J. A. Articles by Hand, S. C. Search for Related Content PubMed PubMed Citation Articles by Covi, J. A. Articles by Hand, S. C.

V-ATPase inhibition prevents recovery from anoxia in Artemia franciscana embryos: quiescence signaling through dissipation of proton gradients

Joseph A. Covi^1,*, W. Dale Treleaven² and Steven C. Hand¹

¹ Division of Cellular, Developmental and Integrative Biology, Department of Biological Science
² NMR Facility, College of Basic Sciences, Louisiana State University, Baton Rouge, LA 70803, USA

^* Author for correspondence (e-mail: jcovi1{at}lsu.edu)

Accepted 11 May 2005

The metabolic downregulation critical for long-term survival of Artemia franciscana embryos under anoxia is mediated, in part, by a progressive intracellular acidification. However, very little is known about the mechanisms responsible for the pH transitions associated with exposure to, and recovery from, oxygen deprivation. In the present study, we demonstrate with ³¹P-NMR that incubation of intact embryos with the V-ATPase inhibitor bafilomycin A₁ severely limits intracellular alkalinization during recovery from anoxia without affecting the restoration of cellular nucleotide triphosphate levels. Based on these data, it appears that oxidative phosphorylation and ATP resynthesis can only account for the first 0.3 pH unit alkalinization observed during aerobic recovery from the 1 pH unit acidification produced during 1 h of anoxia. The additional 0.7 pH unit increase requires proton pumping by the V-ATPase. Aerobic incubation with bafilomycin also suggests that V-ATPase inhibition alone is not enough to induce an acute dissipation of proton gradients under anoxia. In intact embryos, the dissipation of proton gradients and uncoupling of oxidative phosphorylation with carbonyl cyanide 3-chlorophenylhydrazone (CCCP) leads to an intracellular acidification similar to that seen after 1 h of anoxia. Subsequent exposure to anoxia, in the continued presence of CCCP, yields little additional acidification, suggesting that proton gradients are normally dissipated under anoxia. When combined with protons generated from net ATP hydrolysis, these data show that the dissipation of proton chemical gradients is sufficient to account for the reversible acidification associated with quiescence in these embryos.

Key words: vacuolar-type ATPase, CCCP, bafilomycin A₁, quiescence, gradient dissipation, anoxia, acidification, intracellular pH, ³¹P-NMR

Related articles in JEB:

PROTON PUMP IS KEY TO SURVIVING ANOXIA

Yfke van Bergen
JEB 2005 208: ii. [Full Text]  

This article has been cited by other articles:

				S. C. Hand and M. A. Menze Mitochondria in energy-limited states: mechanisms that blunt the signaling of cell death J. Exp. Biol., June 15, 2008; 211(12): 1829 - 1840. [Abstract] [Full Text] [PDF]

				J. S. Clegg Protein Stability in Artemia Embryos During Prolonged Anoxia Biol. Bull., February 1, 2007; 212(1): 74 - 81. [Abstract] [Full Text] [PDF]

				Y. van Bergen PROTON PUMP IS KEY TO SURVIVING ANOXIA J. Exp. Biol., July 15, 2005; 208(14): ii - ii. [Full Text] [PDF]

				J. A. Covi and S. C. Hand V-ATPase expression during development of Artemia franciscana embryos: potential role for proton gradients in anoxia signaling J. Exp. Biol., July 15, 2005; 208(14): 2783 - 2798. [Abstract] [Full Text] [PDF]