FIG. 2.
Northern blot analysis of full-length and mini-tet(L) mRNAs. (A) Decay of wild-type tet(L) mRNA in the absence and presence of Tc. Times (minutes) after rifampin addition are indicated above each lane. Total RNA was separated on a formaldehyde-agarose gel. Bands representing tet(L) mRNA and a tet(L) transcriptional readthrough product that is detected by the tet(L) probe (7) are indicated on the right. (B) Schematic diagram of construction of the mini-tet(L) gene. The top line represents the full-length tet(L) gene, with the promoter (P), leader region, Tet(L) coding sequence (not drawn to scale), and transcription terminator (t). The region deleted to give the mini-tet(L) gene (bottom line) is indicated by Δ. Relevant restriction sites are shown (see Materials and Methods). (C) Northern blot analysis of mini-tet(L) mRNA isolated in the presence and absence of Tc at times (in minutes) after rifampin addition. (D) Northern blot analysis of steady-state mini-tet(L) mRNA in the presence of Tc, Em, or no addition (−).