Rgs16 mRNA regulated in liver by fasting and refeeding. ( A ) Northern blot analysis of liver total RNA (20 μg/lane) isolated from individually caged female mice (C57BL/6) sacrificed at the indicated times (Representative of ≥10 mice/condition). Rgs16 accumulates in fasted mice in either light (lanes 1 and 7) or dark phase (lane 4); Rgs16 is basal within 4 hr of feeding in dark (lanes 2,3,5) or light phase (lane 8). Rgs16 mRNA declines in fasted mice near the end of dark phase (lane 6) before rebounding in the next light phase with continued fasting (lane 7). Solid line represents food and water available ad libitum; dashed line, food removed (water available ad libitum); vertical bar, time when food was removed or provided; solid circle, time of sacrifice. Time line: 12 hr light (open bar), 12 hr dark (filled bar). To confirm equal loading in all lanes, the filter was rehybridized with a radiolabeled oligonucleotide complementary to 18s rRNA. ( B ) QPCR of Rgs16 and PEPCK mRNA from liver of fasted mice. Food was removed at ZT4, and liver samples were collected at the indicated times (n = 6/time point, 3 females/cage) or ( C ) QPCR of Rgs16 mRNA of mice fasted from ZT4 and then fed by gavage (1 ml) at ZT14, either with water or complete liquid diet; mice sacrificed at ZT16; n ≥ 6, 3 females/cage. Fold induction compared to pooled RNA from fed mice (as in Fig. 2A, condition 2). ZT, Zeitgeber Time.