Appearance of vitellogenin mRNA sequences and rate of vitellogenin synthesis in chicken liver following primary and secondary stimulation by 17 beta-estradiol.

Abstract

1 Vitellogenin mRNA present in total liver RNA was determined by hybridization with labeled DNA complementary to vitellogenin mRNA. 2 In the liver of control chicks less than 0.0001% of total cellular RNA hybridized with the vitellogenin cDNA probe. About 6 h after a first estradiol injection (primary stimulation) a significant increase in vitellogenin mRNA was observed. The initial rate of accumulation of mRNA was approximately two molecules per minute per gene, 48 h later we measured a total of 7000 mRNA molecules per diploid genome (or 0.075% of total RNA). 3 Secondary stimulation was initiated 3 weeks later when the concentration of vitellogenin mRNA had returned to the baseline of controls. Upon the second injection of estradiol (secondary stimulation) an immediate increase in the number of vitellogenin mRNA sequences was observed. The initial rate of accumulation of mRNA was approximately six molecules per minute per gene, reaching 48 h later a total of 14000 mRNA molecules per diploid genome (or 0.128% of total cellular RNA). 4 The relative rate of vitellogenin synthesis in vivo was studied by pulse labeling and radioimmunochemical techniques. During the primary stimulation the rate of vitellogenin synthesis in vivo parallels the increase in vitellogenin mRNA concentration and 48 h later vitellogenin represented about 9% of the newly synthesized liver proteins. During the secondary stimulation the rate of vitellogenin synthesis increased first slowly during the first 6 h and then it ran parallel to the accumulation of vitellogenin mRNA. Two days later vitellogenin represented about 16% of the pulselabeled liver proteins.