Studies on a PMCA-like protein in the outer mantle epithelium of Anodonta cygnea: Insights on calcium transcellular dynamics

Manuel Lopes-Lima, Reiner Bleher, Tassilo Forg, Mathias Hafner, Jorge Machado*

*Corresponding author for this work

Research output: Contribution to journalArticle

16 Scopus citations

Abstract

Early studies on the outer mantle epithelium (OME) cells of the freshwater bivalve Anodonta cygnea (Linnaeus, 1758) revealed high ionic calcium concentrations by electrophysiological methods and subsequently a high tendency to reach an intracellular toxic condition. This toxicity could be neutralized by specific mechanisms in the cytosol of OME cells of A. cygnea. The present immunocytochemistry studies of OME cells by light and transmission electron microscopy (TEM) clearly showed a positive reaction of an antibody directed against the human plasma membrane Ca2+-ATPase 1 (PMCA-1) in the cytoplasm of OME cells. Also, western blot analysis of different fractions of OME cells with anti human PMCA-1 and C28R2 antibodies confirmed the presence of a PMCA-like protein with an unusual topographical localization and a molecular weight of only 70-80 kDa. These results lead us to speculate that this PMCA-like protein is distributed either in the plasma membrane or in the entire cytosol, where it eventually regulates intracellular calcium levels. Interestingly, the antibody reactions showed seasonal variations, being highest in OME samples prepared during summer when A. cygnea live under natural acidosis and absent in samples taken in winter conditions, which is in accordance with the seasonal variation of shell calcification rates. During winter, PMCA-1 antibody reaction was also detected in OME cells of animals kept only under experimentally induced acidosis conditions. Therefore, we assume that a functional role for this PMCA-like protein in the intracellular calcium regulation of OME cells during the mineralization of the shells of A. cygnea can be speculated.

Original languageEnglish (US)
Pages (from-to)17-25
Number of pages9
JournalJournal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology
Volume178
Issue number1
DOIs
StatePublished - Jan 1 2008

Keywords

  • Anodonta cygnea
  • Freshwater bivalve
  • Intracellular calcium movement
  • Outer mantle epithelium
  • Shell calcification

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Biochemistry
  • Physiology
  • Animal Science and Zoology
  • Endocrinology

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