title: Ribonucleic acid synthesis in embryonic chick muscle, rates of synthesis and half-lives of transfer and ribosomal RNA species.
abstract: In this study the term 'rates of synthesis' does not refer to rates of transcription but to rates of accumulation of newly synthesized RNA. The rates of synthesis and half-lives of tRNA, 18S and 28S rRNA of 14-day and 17-day embryonic chick muscle were determined by following the accumulation of radioactive AMP in RNA after administration of [3H]8-adenosine to chick embryos and correcting for the average specific activity of the precursor ATP pool Transfer RNA of 14-day embryonic chick muscle is synthesized at a rate of 2.4 x 10(5) molecules per min per 2N DNA content and decays with a half-life of 50h. Transfer RNA of 17-day embryonic chick muscle is synthesized, and decays, at similar rates. Ribosomal RNA, 18S and 28S, are synthesized at a rate of 9.94 x 10(3) and 8.48 x 10(3) molecules per min per 2N DNA, respectively, in 14-day embryonic chick muscle. The rates of rRNA syntheis in 17-day embryonic muscle are also similar. In both 14-day and 17-day embryonic muscle, 18S and 28S rRNA each decays with a half-life of 65h. We conclude that the constant level of tRNA and rRNA in embryonic chick muscle from 14 to 17 days (Nwagwu & Nana, 1974) is maintained also by a constant rate of synthesis and turnover.
mesh_terms: D000241:Adenosine / Q000378:metabolism; D000249:Adenosine Monophosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002642:Chick Embryo; D006207:Half-Life; D007700:Kinetics; D009132:Muscles / Q000196:embryology / Q000378:metabolism*; D012335:RNA, Ribosomal / Q000096:biosynthesis*; D012343:RNA, Transfer / Q000096:biosynthesis*; D013997:Time Factors
chemical_list: D012335:RNA, Ribosomal; D000249:Adenosine Monophosphate; D000255:Adenosine Triphosphate; D012343:RNA, Transfer; D000241:Adenosine