Low-temperature microRNA expression in the painted turtle, Chrysemys picta during freezing stress.

Natural freeze tolerance depends on cellular adaptations that address the multiple stresses imposed on cells during freezing. These adaptations preserve viability by suppressing energy-expensive cell processes in the frozen state. In this study, we explore the freeze-responsive expression of microRNA in hatchling painted turtles exposed to 20 h freezing. Furthermore, we also explore the possibility of unique temperature-sensitive microRNA targeting programs that aid in adapting turtles for survival in the frozen state. Interestingly, two freeze-responsive 'cryo-miRs' (cpm-miR-16 and cpm-miR-21) were found to have unique low-temperature mRNA targets enriched in biological processes that are known to be part of the stress response.