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. 2005 Mar;25(5):1912–1921. doi: 10.1128/MCB.25.5.1912-1921.2005

FIG. 7.

FIG. 7.

Constitutive mPer2 mRNA expression results in rapid dampening of circadian dbp and endogenous mPer2 mRNA expression rhythm. (A) The pTet-Off vector single stably transfected NIH 3T3 cell line exhibited robust circadian oscillation of mPer2 and dbp mRNA expression without apparent dampening for 3 days. (B) The P2-#19 Tet-Off/mPer2 double stable cell line cultured with doxycycline [Dox(+)] also showed circadian endogenous mPer2 (represented as 3′ noncoding) and dbp mRNA expression after serum shock for 2 days. However, amplitude was rapidly dampened, and no apparent rhythm was observed during the third day. (C and D) Expression profiles of dbp (C) and endogenous mPer2 (D) quantified from panels A and B. Open squares with broken lines represent pTet-Off single stably transfected NIH 3T3 cells, and solid circles with solid lines represent the P2-#19 cell line under Dox+ conditions. Error bars represent means ± standard errors of the mean. (n = 3).