Figure 1. Development of mRNA levels for melatonin-synthesizing enzymes and phototransduction proteins

Total RNA (15 μg) was extracted from 10 to 30 neural retinas at the indicated developmental stages and analyzed on northern blots with the indicated ³²P-labeled cDNA probes. A ³²P-labeled 18S rRNA oligonucleotide was used to verify equal RNA loading in the different lanes. A: After analysis on a broad time scale, the successive appearances of visinin, α-transducin, HIOMT, and AANAT mRNAs are illustrated. For clarity, the detection of all opsin mRNAs is summarized by (-) or (+). The results are representative of two independent experiments analyzed on four northern blots. B: Analysis on a higher resolution time scale allows a closer comparison of the different timing of gene activation for the melatonin-synthesizing enzymes and for the five opsins. The results are representative of one experiment analyzed on two northern blots.