FIG. 1.
Expression of tropoelastin pre-mRNA persists in adult tissue. (A) Total RNA was isolated from lungs of 19-day fetuses, 3- and 11-day-old neonates, and 6-month-old adult rats and analyzed by Northern hybridization for tropoelastin and GAPDH mRNAs. Ethidium bromide staining of the gel before transfer (smaller panel) confirmed equivalent loading among lanes. (B) The same RNA samples were amplified by RT-PCR with intron-35 primers. Products were detected by Southern hybridization with 32P-labeled intron-specific oligomeric probe. No signal was detected in samples processed without reverse transcriptase (data not shown). (C) Autoradiographic signal for tropoelastin mRNA and pre-mRNA was quantified and normalized to the signal for the 11-day-old neonate sample, which was arbitrarily set at 25. The autoradiographic signal density of tropoelastin mRNA is expressed relative to that of GAPDH mRNA (data not shown).