Exploration of low temperature microRNA function in an anoxia tolerant vertebrate ectotherm, the red eared slider turtle (Trachemys scripta elegans).

As a model for vertebrate long-term survival in oxygen-restricted environments, the red-eared slider turtle (Trachemys scripta elegans) can adapt at the biochemical level to survive in oxygen-free (anoxic) cold water (<10°C). This impressive ability is enabled through a coordinated suppression of energy-expensive, non-essential, cell processes. This study explored the anoxia-responsive expression of several microRNA species (miR-1a, -133, -17, -107, -148a, -21, -103, -210, -20a, -365 and -29b) in adult turtles exposed to 5h and 20h anoxia (at 5±1°C). Furthermore, since microRNA target binding is regularly defined only by microRNA-mRNA interactions at 37°C, the possibility of unique low temperature-selective microRNA targeting interactions with mRNA was explored in this ectotherm. Approximately twice as many microRNA-mRNA interactions were predicted at 5°C versus 37°C with particular enrichment of mRNA targets involved in biological processes known to be part of the stress response. Hence, the results suggest that the influence of temperature should be considered for the prediction of microRNA targets (and their follow-up) in poikilothermic animals and that interacting effects of low body temperature and anoxia on microRNA expression could potentially be important to achieve the profound metabolic rate depression that characterizes turtle hibernation underwater during the winter.