In response to cold or food deprivation, many mammals enter a state of metabolic depression. This metabolic depression may be short in duration (i.e. daily torpor) or extensive (i.e. denning in bears). The principal focus of my laboratory is mammalian hibernation in golden-mantled ground squirrels (Spermophilus lateralis). Hibernation can accrue a net energetic savings of 90% over the course of a season. During hibernation, their core body temperatures may be as low as -2 C and their metabolic rates can approach 1/100th of normothermic rates. Hibernation is not static. Rather, the animals cycle through a torpor bout in 1-3 week intervals (see above figure) and these cycles are repeated throughout the six to nine month season. There are a tremendous number of physiological implications in cycling between 37 C and -2 C. Heart rate drops from around 200 bpm to 2-4 bpm. Pathways of metabolism must be depressed or suppressed and then resurrected between bouts of torpor. Entire organ systems are turned off. Yet, in an almost magical way, these animals spontaneously arouse. My interests are in how the animals survive theses physiological shifts. Currently, we are investigating the depression of translation in hibernators. Protein sysnthesis accounts for as much as 30% of basal metabolic rate. Such an energetic expenditure is at odds with an energy-sparing process like hibernation. We are investigating the mechanisms of translational depression and the implications of that depression to physiological regulation.