Gene Expression and Physiological Changes of Different Populations of the Long-Lived Bivalve Arctica islandica under Low Oxygen Conditions

The Ocean Quahog, Arctica islandica, is regarded a prodigious new study object in aging research. It is the longest-lived non colonial animal species on earth with an extreme tolerance of low environmental oxygen levels. Individuals were found to live >400 years (Wanamaker et al., 2008) and to survive extended periods without oxygen (50% survival rate after 55 days of anoxia, Theede et al. (1969)). Seven independent transcriptomal data sets of A. islandica were generated using 454 technology (454 Life Sciences, Branford, CT, USA). To maximize the diversity of expressed stress- and immune-related transcripts in the experimental material, A. islandica individuals were exposed to different stressors and different tissues (gill, digestive gland) were used for RNA extraction. Briefly, A. islandica individuals were collected in March 2008 in the Baltic Sea (Germany) at the sampling station “Süderfahrt” (54° 32.6’ N, 10° 42.1’ O) in 20m water depth with a hydraulic dredge. Animals were kept in a constant temperature room at 10 °C with a flow-through of natural unfiltered seawater from Kiel Bay. After 1 week of acclimation, animals were exposed to different experimental conditions (2 animals each): high temperature (20°C); anoxia: wrapped in a double layer of parafilm, and injury: cracking the shell. Control animals were kept at 10 °C in flow-through seawater. After 5 days, the animals were taken from each experiment, dissected and tissues frozen in liquid nitrogen. From these experiments digestive gland and gill tissue was used for sequence generation. To further enhance the number of transcripts, gill tissue of three young (27, 19 and 22 years of age) and two old (148 and 150 years of age) Arctica islandica individuals from an Icelandic population were used for transcriptome generation, which were collected by J. Strahl in July 2004 and May 2005 Northeast of Iceland (66°01.54´N, 14°50.98`W) between 14 and 22 m water depth using a hydraulic dredge. Animal processing and age determination by year ring counts in the shell is described in detail in Strahl et al (2007).