Figure 1.
Expression of PDK-4 during the hibernation season. (A) Northern blot of total RNA from the hearts of active and hibernating 13-lined ground squirrels. The position and size of PDK-4 mRNA are indicated. Body temperature (Tb), ambient temperature (Ta), and month of sacrifice are indicated above each lane. The state of each animal is indicated as active (A), hibernating (H), or in interbout arousal (I). The actin profile is shown directly below. August through October animals and December through May animals represent two separate sibling groups from mothers captured in Michigan. (B) Bar graph summarizing PDK-4 mRNA levels in the hearts of sibling and nonsibling ground squirrels captured in Michigan and Illinois (TLS Research, Bartlett, IL). PDK-4 mRNA levels were quantified by a PhosphorImager (Molecular Dynamics). For each experiment the PDK-4 value for the August animal was normalized to 1.00. Each bar represents mean values derived from RNA blot experiments (±SEM). Body temperature, state, month(s) of sacrifice, and the number of animals (n) are indicated below each group. HIB, hibernating; IBA, interbout arousal. Statistically significant comparisons to August mRNA levels were determined by one-way ANOVA: ∗, 0.01 < P < 0.05; ∗∗, P ≤ 0.01. (C) Tissue distribution of PDK-4 mRNA from a single hibernating animal sacrificed in January during hypothermic torpor (Tb = 5°C). Tissues are as indicated above each lane and the actin profile for this blot is shown in Fig. 2C. Sk. muscle, skeletal muscle.