Abstract
Low molecular weight RNAs were isolatedfrom nuclei of the cellular slime moldDictyostelium discoideum AX-3. Analysis of the RNAs by polyacrylamide gel electrophoresis showedthat the vegetative cell nuclei contained, besides tRNA (Dd1), 5 S RNA (Dd4), and5.8 S RNA (Dd7), at least 7 small RNA species (Dd3, Dd5, Dd6, Dd8, Dd9, Dd10, Dd11) of 4 S to 8 S as major components andthat the 7 small RNAs were localizedmainly in the nucleus andhadno poly (A) sequence. These nuclear RNA species were metabolically stable, as shown by a chase experiment. Dd6, Dd8, andDd9 hadsimilar gel electrophoretic mobilities to those of the small nuclear RNA species U 1, U 2, andU 3, respectively, of rat liver. Analysis of the 5' -terminus of these RNA molecules with tobacco acidphosphodiesterase suggestedthat Dd6, Dd8, andDd9 each contain a cap. Sequence analysis of the 3' -endlabeledDd9 RNA showedthat the 3' -terminal region sequencedhadsequence homology with that of rat Novikoff hepatoma U 3 RNA. These results indicate that Dictyostelium nuclei contain a set of small nuclear RNA species which is structurally similar to that in mammalian cells. No qualitative differences were detectedbetween the small nuclear RNA species of vegetative andearly differentiating cells.
