Universal DNA methylation age across mammalian tissues.

Aging, often considered a result of random cellular damage, can be accurately estimated using DNA methylation profiles, the foundation of pan-tissue epigenetic clocks. Here, we demonstrate the development of universal pan-mammalian clocks, using 11,754 methylation arrays from our Mammalian Methylation Consortium, which encompass 59 tissue types across 185 mammalian species. These predictive models estimate mammalian tissue age with high accuracy (r > 0.96). Age deviations correlate with human mortality risk, mouse somatotropic axis mutations and caloric restriction. We identified specific cytosines with methylation levels that change with age across numerous species. These sites, highly enriched in polycomb repressive complex 2-binding locations, are near genes implicated in mammalian development, cancer, obesity and longevity. Our findings offer new evidence suggesting that aging is evolutionarily conserved and intertwined with developmental processes across all mammals.

The blood chemical status of Atlantic cod Gadus morhua following capture by jig and demersal longline with differential hook removal methods.

Common haematological [haematocrit (Hct)], primary (serum cortisol) and secondary (serum glucose and plasma lactate) analytes were utilized to compare blood biochemical status of Gadus morhua captured rapidly by jig with that of G. morhua captured by commercial demersal longline. In general, the physiological status of G. morhua, despite blind hook times, was significantly more disrupted (pronounced haemo-concentration and significantly elevated concentrations of cortisol, glucose and lactate) following longline capture relative to capture by jig, while no differences were detected among longline-caught fish as a function of dehooking method (or concomitant extent of overt physical trauma). Blood profiles from the more stressed G. morhua, a possible function of more extended longline hook times, were similar to the most stressed values reported for this species. The results also demonstrate that, although acute blood biochemical status is an effective gauge of relative stress, it does not reflect physical injury status, which has been shown to exert a strong influence on delayed mortality in previous studies in this species. Thus, acute blood chemical status alone may not be the most complete predictor of mortality. Future studies should evaluate physiological repercussions from capture-handling against physical trauma during more extended post-release periods for this species.