Meeting Abstract
Oxygen variability represents a major stressor for aerobic organisms, and mitochondria are the main target of hypoxia-reoxygenation (H/R) injury. Many hypoxia-tolerant species such as intertidal bivalves are adapted to frequent and drastic oxygen fluctuations, but the mechanisms allowing their mitochondria to maintain integrity and function under these conditions are not well understood. We investigated the effects of H/R stress (24 h of hypoxia followed by 1 h of recovery) on mitochondrial (phospho-)proteome in an intertidal bivalve, the Pacific oyster Crassostrea gigas . Oyster mitochondria showed functional robustness maintaining oxidative phosphorylation capacity and mitochondrial membrane potential during H/R stress. The functional stability of oyster mitochondria associated with rearrangements of mitochondrial proteome and phosphoproteome that started in hypoxia but became considerably more pronounced during reoxygenation. Exposure to H/R stress upregulated mitochondrial electron transport system proteins (most notably Complexes I and IV), suppressed pathways channeling electrons to ubiquinone, stimulated mitochondrial quality control mechanisms and modulated protein synthesis and transport pathways. These shifts in the mitochondrial proteome may play an important role in adaptive responses to intermittent hypoxia in oysters complementing adaptive shifts in anaerobic metabolism and metabolic rate depression.
