Comparing Longevity and Damage Resistance in Bivalves

Much like mammals, bivalve molluscs exhibit a very wide range of life spans. At the known outer end stands the arctic quahog at more than four centuries, and much studied in recent years so as to understand the roots of its longevity. That research project is still ongoing, as are similar comparative studies of aging and longevity in a range of other species.

Here, researchers compare resistance to various forms of physical stress and damage in different bivalve species. As you might expect from the view of aging put forward earlier today, longer-lived species are more resistant to most forms of damage:

Bivalve molluscs are newly discovered models of successful aging. Here, we test the hypothesis that extremely long-lived bivalves are not uniquely resistant to oxidative stressors (eg, tert-butyl hydroperoxide, as demonstrated in previous studies) but exhibit a multistress resistance phenotype.

We contrasted resistance (in terms of organismal mortality) to genotoxic stresses (including topoisomerase inhibitors, agents that cross-link DNA or impair genomic integrity through DNA alkylation or methylation) and to mitochondrial oxidative stressors in three bivalve mollusc species with dramatically differing life spans: Arctica islandica (ocean quahog), Mercenaria mercenaria (northern quahog), and the Atlantic bay scallop, Argopecten irradians irradians (maximum species life spans: more than 500, more than 100, and ~2 years, respectively).

With all stressors, the short-lived A i irradians were significantly less resistant than the two longer lived species. Arctica islandica were consistently more resistant than M mercenaria to mortality induced by oxidative stressors as well as DNA methylating agent nitrogen mustard and the DNA alkylating agent methyl methanesulfonate. The same trend was not observed for genotoxic agents that act through cross-linking DNA. In contrast, M mercenaria tended to be more resistant to epirubicin and genotoxic stressors, which cause DNA damage by inhibiting topoisomerases.

To our knowledge, this is the first study comparing resistance to genotoxic stressors in bivalve mollusc species with disparate longevities. In line with previous studies of comparative stress resistance and longevity, our data extends, at least in part, the evidence for the hypothesis that an association exists between longevity and a general resistance to multiplex stressors, not solely oxidative stress.

In mammals, you might look to the naked mole rat as an analogous species: very resistant to all sorts of biological and cellular damage, and extremely long-lived in comparison to similar sized rodent species.

Link: http://www.ncbi.nlm.nih.gov/pubmed/23051979

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