Environmental conditions shape molluscan lifespan: comparing markers of cellular fitness and aging in two populations of the freshwater bivalve Diplodon chilensis

ROCCHETTA, IARA

Cambridge

Congreso; The 7th Congress of the European Malacological Societies; 2014

Bivalves can be aged by counting the growth rings in their shells and are emerging new models in aging studies. The unionide Diplodon chilensis is abundant in rivers and lakes of Andean Patagonia and can reach more than 100 years. Two natural populations from a river and a lake in Patagonia (Argentina) were studied to analyse the effects of abiotic and biotic environment factors on fitness and senescence. Oxidative stress (malondialdehyde (MDA), protein carbonyls) and apoptosis markers (caspase3-7 activities) in mantle tissue, antioxidant enzymes (catalase (CAT) and superoxide dismutase) and metabolic enzyme activities in gills (citrate synthase (CS) and cytochrome oxidase) were analysed over age. Maximum population lifespan was 120 years in the lake and only 40 years in the river. When comparing the same age at both sites, individuals from the river have higher CAT activities and lower lipid oxidation levels (MDA). Furthermore, apoptosis and protein oxidation intensities were higher in bivalves of river than lake individuals, which could mean that protein turnover is faster in the river bivalves. Even more, stress gene expression (SOD, HSP70-90, GST, GPX, apoptosis) was higher in river individuals compared to the same age group from the lake. Plotted over lake population lifetime, same pattern of river bivalves is observed. CAT activity was increased and MDA levels in individuals diminish with age, while the age pigment lipofucsin, protein carbonyls and caspase activity increased over age. Metabolism activity would seem to be slower in the older bivalves, deduced from lower CS. In conclusion, the river represents a more stressful (variable) environment than the lake in which bivalves have to invest more energy into stress defense and tissue maintenance (apoptosis). This contributes to the 3-fold higher population specific life expectancy in the lake.