title: Counting the genes for stabel RNA in the nucleus and chloroplasts of Euglena.
abstract: Improved procedures for counting the genes for ribosomal and 4 S RNA in the nucleus and chloroplasts of Euglena are described. These procedures exploit (a) the chloroplast-free strain ZHB, (b) the flotation method for purifying chloroplasts, (c) Hg2+/Cs2SO4 density gradients to fractionate large quantities of DNA and (d) more efficient conditions of DNA - RNA hybridization particularly for 4 S RNA. We find that the average Euglena cell in an exponentially growing culture contains 800 nuclear genes for each cytoplasmic rRNA and 800-880 chloroplast genes for chloroplast rRNA. Each chloroplast chromosome of molecular weight 92 - 10(6) contains two genes for each rRNA. The number of nuclear genes for 4 S RNA is approx. 760. The total number of chloroplast genes for 4S RNA is approx. 10 000, or 22-25 on each chloroplast chromosome.
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D002467:Cell Nucleus / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism*; D004247:DNA / Q000302:isolation & purification; D005056:Euglena gracilis / Q000378:metabolism*; D005796:Genes; D007700:Kinetics; D009691:Nucleic Acid Denaturation; D009693:Nucleic Acid Hybridization; D012313:RNA / Q000378:metabolism; D012335:RNA, Ribosomal / Q000096:biosynthesis / Q000302:isolation & purification; D013045:Species Specificity; D013696:Temperature; D014158:Transcription, Genetic
chemical_list: D012335:RNA, Ribosomal; D012313:RNA; D004247:DNA