Can environmental conditions change molluscan lifespan?

IARA ROCCHETTA

Conferencia; II International Conference on Oxidative Stress in Aquatic Ecosystems; 2015

The freshwater bivalve Diplodon chilensis is abundant in rivers and lakes of Andean Patagonia and can reach more than 100 years of age, which makes it a promising model for aging studies. Bivalves from Chimehuin river and Paimun lake (Limay Basin, Argentina) were studied to analyze the effects of environmental factors on fitness and lifespan. Different markers for oxidative stress (lipofuscin, malondialdehyde (MDA), protein carbonyls, catalase (CAT) and superoxide dismutase, (SOD)), apoptosis (caspase3-7), metabolic enzymes (citrate synthase(CS) and cytochrome oxidase), and stress gene expression were analyzed in gills,in relation to age. Maximum population lifespan was 120years in the lake and 40 years in the river. Individuals from the river had higher CAT activities, lower MDA levels and higher apoptosis and protein oxidation intensities than lake individuals of the same age, which suggests faster protein turnover in the river bivalves, in concordance with their higher growth rate. Furthermore,the expression of stress (SOD, HSP70-90, GST, GPX, GSHSynthetase, AOx, apoptosis)and metabolism (CS, GlyPhosphorilase, PK) genes was higher in river than in lake individuals. Young animals of both populations, before the onset of maturation(0-10 yrs), showed higher gene expression compared to 11-40 yrs animals. Plottedover lake population lifetime (0-120 yrs), same pattern of river bivalves wasobserved. CAT activity increased and MDA levels diminished with age, while lipofuscinand protein carbonyl concentration and also caspase activity increased with age.Metabolic capacity seems to decrease in the older bivalves deduced from a reduction of CS activity. In conclusion, environmental conditions can shape molluscan lifespan. The process of ageing is the same in both populations, but a more stressful environment (river) seems to accelerate the rate of aging. River bivalves have to invest more energy in stress defence and tissue maintenance (apoptosis) due to their higher metabolic expenses.