Telomere-independent ageing in the longest-lived non-colonial animal, Arctica islandica

Abstract

The shortening of telomeres as a causative factor in ageing is a widely discussed hypothesis in ageing research. The study of telomere length and its regenerating enzyme telomerase in the longest-lived non-colonial animal on earth, Arctica islandica, should inform whether the maintenance of telomere length plays a role in reaching the extreme maximum lifespan (MLSP) of N500 years in this species. Since longitudinal measurements on living animals cannot be achieved, a cross-sectional analysis of a short-lived (MLSP 40 years from the Baltic Sea) and a long-lived population (MLSP 226 years Northeast of Iceland) and in different tissues of young and old animals from the Irish Sea was performed. A high heterogeneity of telomere length was observed in investigated A. islandica over a wide age range (10-36 years for the Baltic Sea, 11-194 years for Irish Sea, 6-226 years for Iceland). Constant telomerase activity and telomere lengths were detected at any age and in different tissues; neither correlated with age or population habitat. Stable telomere maintenance might contribute to the long lifespan of A. islandica. Telomere dynamics are no explanation for the distinct MLSPs of the examined populations and thus the cause of it remains to be investigated.

Age-related cellular changes in the long-lived bivalve A. islandica

“…While our observations of higher deoxyguanosine oxidation over time would otherwise suggest shortening of G-rich telomeric repeat sequences with number of cell divisions, telomeric maintenance capacity is stable with age in both A. islandica populations (Gruber et al 2014). In addition, our data do not support the hypothesis that protein maintenance is impaired by chronic oxidative stress leading to protein misfolding, protein oxidation, and decreasing protein stability with age (Pérez et al 2009).…”

“…After 5 days of recovery from sampling stress, animals were dissected and gill tissues were sampled, shock-frozen in liquid nitrogen, and stored at −80°C. Ages were determined as in Gruber et al (2014) by counting each shell's annual growth rings (Witbaard et al 1994;Schöne et al 2005). …”

“…In addition, genetic analyses classify both A. islandica populations into the same species regardless of MLSP (Dahlgren et al 2000;Glöckner et al 2013). Long-lived ocean quahogs show little decline in telomere maintenance, protein carbonylation, and antioxidant capacities with age; they also have low susceptibility to genotoxic stresses, including topoisomerase inhibitors (Strahl et al 2007;Abele et al 2008;Ungvari et al 2011Ungvari et al , 2013Gruber et al 2014). The short-lived Baltic Sea population experiences high environmental stress throughout the year (e.g., fluctuations in temperature, oxygen availability, salinity), while the long-lived Icelandic population lives in a relatively constant environment (Basova et al 2012).…”

Telomere length decreases during ontogeny in peled

“…The obtained data allowed telomeres to be attributed to one of the nine key biomarkers of ageing (López-Otín et al, 2013). At the same time, there are some examples in various taxonomic groups when the age-related dynamics of telomeric DNA (tDNA) has a different type: in mollusks (Gruber et al, 2014;Maximova et al, 2017), fish (Gao and Munch, 2015), reptiles (Paitz et al, 2004), birds (Caprioli et al, 2013), etc. Normally, tDNA dynamics is associated with telomerase activity, an enzyme that maintains the telomere length (Greider and Blackburn, 1989).…”

Energy excess is the main cause of accelerated aging of mammals

“…The fish Hoplostethus atlanticus is probably one the longest recently vertebrates (150 years or more) [ 40 , 41 ] among vertebrates. Bivalve edible mollusk Arctica islandica lives for more than 500 years [ 42 ]. Finding a common denominator for these diverse organisms is not easy.…”