Description: The bivalve Arctica islandica is extremely long lived (〉400 years) and can tolerate long periods of hypoxia and anoxia. European populations differ in maximum life spans from 40 years in the Baltic to 〉400 years around Iceland. Characteristic behavior In their natural environment and under laboratory conditions,of A. islandica performs involves phases of metabolic rate depression (MRD) during which the animals burry into the sediment for several days and which suggested possibly supporting the long life span of some populations. The animals burrow into the sediment for some days an In the buried state d lower shelshell water oxygen concentrations to hypoxic andreaches even anoxic levels. In the present study wWe investigated gene regulation in individuals A. islandica fromof the a longer- lived (MLSP 150years) German Bight population and the a shorter- lived Baltic Sea population, experimentally exposed to different oxygen levels. A new A. islandica transcriptome enabled the identification of genes important during hypoxia/anoxia events and, more generally, gene mining for putative stress response and (anti-) aging genes. Exposed to low oxygen (0 and 2 kPa) conditions, German Bight individuals generally suppress gene transcription, whereas Baltic Sea bivalves enhanced gene transcription under anoxic incubation (0 kPa), and, further, decreased these transcription levels again during 6h of re-oxygenation. Hypoxic and anoxic exposure and subsequent re-oxygenation in Baltic Sea animals did not lead to increased protein oxidation or induction of apoptosis, emphasizing considerable hypoxia/re-oxygenation tolerance of in this species. The data suggest that the energy saving effect of MRD may not be an attribute of Baltic Sea A. islandica chronically exposed to high environmental variability of oxygenation and also temperature and salinity. Contrary, higher physiological flexibility and stress hardening may predispose these animals to perform a pronounced stress response at the expense of life span.

Description: Increase in oxidative damage and decrease in cellular maintenance is often associated with aging, but, in marine ectotherms, both processes are also strongly influenced by somatic growth, maturation and reproduction. In this study, we used a single cohort of the short-lived catarina scallop Argopecten ventricosus, to investigate the effects of somatic growth, reproduction and aging on oxidative damage parameters (protein carbonyls, TBARS and lipofuscin) and cellular maintenance mechanisms (antioxidant activity and apoptosis) in scallops, caged in their natural environment. The concentrations of protein carbonyls and TBARS increased steeply during the early period of fast growth and during reproduction in one-year-old scallops. However, oxidative damage was transient, and apoptotic cell death played a pivotal role in eliminating damage in gill, mantle and muscle tissues of young scallops. Animals were able to reproduce again in the second year, but the reduced intensity of apoptosis impaired subsequent removal of damaged cells. Fast accumulation of the age pigment lipofuscin was observed in late survivors. Reproduction had a temperature independent effect on oxygen uptake and on oxidative stress markers in first year scallops. Compared to longer-lived bivalves, A. ventricosus seems more susceptible to oxidative stress with higher tissue-specific protein carbonyl levels and fast accumulation of lipofuscin in animals surviving the first and second spawning. Superoxide dismutase activity and apoptotic cell death intensity were higher in this short-lived scallop than in longer-lived bivalves. The life strategy of this short-lived and intensely predated scallop supports rapid somatic growth and fitness as well as early maturation at young age over cellular maintenance in second year scallops.