Abstract
Mitochondria from the embryos of brine shrimp (Artemia franciscana) do not undergo Ca2+-induced permeability transition in the presence of a profound Ca2+ uptake capacity. Furthermore, this crustacean is the only organism known to exhibit bongkrekate-insensitive mitochondrial adenine nucleotide exchange, prompting the conjecture that refractoriness to bongkrekate and absence of Ca2+-induced permeability transition are somehow related phenomena. Here we report that mitochondria isolated from two other crustaceans, brown shrimp (Crangon crangon) and common prawn (Palaemon serratus) exhibited bongkrekate-sensitive mitochondrial adenine nucleotide transport, but lacked a Ca2+-induced permeability transition. Ca2+ uptake capacity was robust in the absence of adenine nucleotides in both crustaceans, unaffected by either bongkrekate or cyclosporin A. Transmission electron microscopy images of Ca2+-loaded mitochondria showed needle-like formations of electron-dense material strikingly similar to those observed in mitochondria from the hepatopancreas of blue crab (Callinectes sapidus) and the embryos of Artemia franciscana. Alignment analysis of the partial coding sequences of the adenine nucleotide translocase (ANT) expressed in Crangon crangon and Palaemon serratus versus the complete sequence expressed in Artemia franciscana reappraised the possibility of the 208-214 amino acid region for conferring sensitivity to bongkrekate. However, our findings suggest that the ability to undergo Ca2+-induced mitochondrial permeability transition and the sensitivity of adenine nucleotide translocase to bongkrekate are not necessarily related phenomena.
Highlights
Mitochondria probed from a vast diversity of tissues and species exhibit the property of Ca2+ sequestration [1]; upon reaching a threshold for Ca2+ uptake capacity, these organelles undergo a permeability transition [2], substantiated by the assembly of pores of a sufficient size
Mindful of i) the well-established ligand-profile of the adenine nucleotide translocase (ANT), ii) the modulatory role of ANT in mammalian permeability transition pore (PTP), and iii) the absence of Ca2+-induced PTP in mitochondria from the embryos of Artemia franciscana, we recently addressed the effect of ANT ligands on Ca2+ uptake capacity in mitochondria isolated from brine shrimp embryos
We hereby show that mitochondria from the malacostraca Crangon crangon and Palaemon serratus lacked a Ca2+induced PTP, yet ADP-ATP exchange mediated by the ANT was sensitive to BKA
Summary
Mitochondria probed from a vast diversity of tissues and species exhibit the property of Ca2+ sequestration [1]; upon reaching a threshold for Ca2+ uptake capacity, these organelles undergo a permeability transition [2], substantiated by the assembly of pores of a sufficient size (cut-off ,1,5 kDa). This allows the passage of solutes and water, resulting in the swelling and rupture of the outer mitochondrial membrane [3]. This allows the suggestion that crustaceans lack the specific machinery for orchestrating the Ca2+-induced permeability transition pore (PTP)
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