DIURNAL EXPRESSION OF RECOVERIN IN THE RAT RETINA

The levels of expression of recoverin mRNA and protein was examined du ring a 24-h period in the rat retina. Northern blot analysis revealed that rat recoverin mRNA expression was consistently high during the li ght period, then decreased after onset of darkness, and gradually incr eased later during the dark period. The cyclic rhythm in recoverin pro tein expression was consistent with the cyclic rhythm in recoverin mRN A expression, insofar as recoverin mRNA and protein levels were lowest soon after lights off, and there was an increase in expression late i n the dark period. These observations suggest that the rate of recover in transcription may occur maximally during the period of greatest exp osure to light, presumably when it is most needed by the photoreceptor to fulfill its role in visual transduction, then decreases at night, when high levels of expression are not required.