ΦΑΣΜΑ ΔΡΑΣΗΣ ΤΗΣ ΜΕΤΑΓΡΑΦΗΣ ΤΟΥ CAB ΓΟΝΙΔΙΟΥ ΚΑΙ ΤΟΥ ΠΡΟΙΟΝΤΟΣ ΤΟΥ ΚΑΤΑ ΤΗΝ ΣΤΑΘΕΡΟΠΟΙΗΣΗ ΤΟΥ ΣΤΟ ΘΥΛΑΚΟΕΙΔΕΣ

Abstract

IN AN ATTEMPT TO ASCERTAIN THAT THE PHYTOCHROME CHROMOPROTEINS DO INDEED CONSTITUTE THE PHOTORECEPTOR INVOLVED IN LHC-II-APOPROTEIN-TRANSCRIPT ACCUMULATION AND THE SYNCHRONIZATION OF THE ENDOGENOUS CIRCADIAN CLOCK, WE STUDIED THEACTION SPECTRUM OF CAB TRANSCRIPTION AND ITS REVERSAL BY FAR-RED LIGHT, IN 9-10-DAY-OLD ETIOLATED PHASEOLUS VULGARIS LEAVES. TRANSCRIPT ACCUMULATION WASDETECTED BY HYBRIDIZATION EXPERIMENTS OR IMMUNOPRECIPITATION OF THE IN VITRO TRANSLATION PRODUCTS, OBTAINED FROM ISOLATED LEAF POLY(A)-RICH MRNA SPECIES. IT WAS FOUND THAT THE ACCUMULATION OF THE PRECURSOR-LHC-II- APOPROTEIN MRNA DEPENDS HIGHLY ON THE WAVELENGTH OF LIGHT EXPOSURE, THE ACTION SPECTRUM OF ITS ACCUMULATION BEING CLOSELY CORRELATED WITH ABSORPTION SPECTRUM OF THE PR FORM; WE ALSO CONCLUDE THAT PROBABLY THE PFR FORM OF PHYTOCHROME MEDIATING CAB-GENE TRANSCRIPTION IS THAT OF TYPE I (PIFR). IN ADDITION, IMMUNOBLOT ANALYSIS OF TOTAL LDS-SOLUBILIZED PROTEIN EXTRACTS OF LEAVES PREVIOUSLY EXPOSED UNDER THE SAME LIGHT CONDITIONS, CLOSELY FOLLOWS THE PATTERN OF ITS TRANSCRIPT ACCUMULATION AND THE ACTION SPECTRUM OF PROTOCHLOROPHYLLIDE PHOTOCONVERSION. SIMILAR LIGHT-DEPENDANCE PATTERN SHOWS THE MATURE D1, REACTION CENTER, PROTEIN CLOSELY COORDINATED WITH THE MATURE LHC-II PROTEIN. ON THE CONTRARY, THE PSI REACTION CENTER PROTEIN (CPI) APPEARS INDEPENDANCE FROM THE LIGHT QUALITY.