The longest-lived metazoan, Arctica islandica, exhibits high mitochondrial H2O2 removal capacities.

[Display omitted] • Mitochondria from the extremely long-lived marine bivalve Arctica islandica consumes 3–14 times more hydrogen peroxide than two shorter-lived counterparts. • This finding supports previous results on mammals and points to consumption of reactive oxygen species (ROS), as a key determinant of a long-lived mitochondrial phenotype. • Overall, these results support the mitochondrial oxidative stress theory of aging (MOSTA), although more work needs to be done to assess net production of hydrogen peroxide in these species. A greater capacity of endogenous matrix antioxidants has recently been hypothesized to characterize mitochondria of long-lived species, curbing bursts of reactive oxygen species (ROS) generated in this organelle. Evidence for this has been obtained from studies comparing the long-lived naked mole rat to laboratory mice. We tested this hypothesis by comparing the longest-lived metazoan, the marine bivalve Arctica islandica (MLSP = 507 y), with shorter-lived and evolutionarily related species. We used a recently developed fluorescent technique to assess mantle and gill tissue mitochondria's capacity to consume hydrogen peroxide (H 2 O 2) in multiple physiological states ex vivo. Depending on the type of respiratory substrate provided, mitochondria of Arctica islandica could consume between 3 and 14 times more H 2 O 2 than shorter-lived species. These findings support the contention that a greater capacity for the elimination of ROS characterizes long-lived species, a novel property of mitochondria thus far demonstrated in two key biogerontological models from distant evolutionary lineages. [ABSTRACT FROM AUTHOR]