title: Spectroscopic evidence for the uneven distribution of adenine and uracil residues in ribosomal ribonucleic acid of Drosophila melanogaster and of Plasmodium knowlesi and its possible evolutionary significance.
abstract: RNA was isolated from subribosomal particles of the malaria parasite Plasmodium knowlesi. The nucleotide composition (mole fraction) of the principal species was obtained (S-rRNA, 0.295A, 0.36U, 0.25G, 0.105C: L-rRNA, 0.326A, 0.31U, 0.228G, 0.144C). Ribosomal RNA was also isolated from Drosophila melanogaster. Optical properties of these A + U-rich species were measured. In all four cases analysis of the hypochromic effect revealed that adenine and uracil residues tended to form clusters along the polynucleotide chain. A substantial fraction of residues was located in bihelical regions of approx. 50% G-C base pairs or in regions of approx. 30-35% G-C base pairs. The possible evolutionary significance of these results was considered on the basis of comparison with properties of rRNA from bacteria (Escherichia coli) and a mammal (rabbit reticulocyte).
mesh_terms: D000225:Adenine / Q000032:analysis*; D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D004331:Drosophila melanogaster / Q000032:analysis*; D004926:Escherichia coli / Q000032:analysis; D010961:Plasmodium / Q000032:analysis*; D012329:RNA, Bacterial; D012335:RNA, Ribosomal / Q000032:analysis*; D011817:Rabbits; D013053:Spectrophotometry; D013696:Temperature; D014498:Uracil / Q000032:analysis*
chemical_list: D012329:RNA, Bacterial; D012335:RNA, Ribosomal; D014498:Uracil; D000225:Adenine