Two distinct intervening sequences in different ribosomal DNA repeat units of Sciara coprophila.
We have prepared a partial gene library of sheared DNA from the fungus fly, Sciara coprophila, by dA-T tailing and insertion into pBR322. Two ribosomal DNA clones which differ from the usual ribosomal DNA organization in this organism were studied in detail. Clone pBc 1L-1 has an intervening sequence of 1.4 kb, and clone pBc 6D-6 has an intervening sequence of 0.9 kb. These intervening sequences occur in about the same position in 28S rDNA, but do not appear to share sequence homology with one another. Previously we found that 90% of Sciara ribosomal DNA is homogenous and lacks an intervening sequence, and our present data explains the size heterogeneity found in most of the remaining 10%. We have found no evidence of size heterogeneity in the nontranscribed spacer.
D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004247:DNA / Q000302:isolation & purification; D004261:DNA Replication; D004274:DNA, Recombinant; D004175:Diptera / Q000235:genetics*; D008297:Male; D008854:Microscopy, Electron; D009690:Nucleic Acid Conformation; D009693:Nucleic Acid Hybridization; D012270:Ribosomes / Q000032:analysis*; D014158:Transcription, Genetic
D004274:DNA, Recombinant; D004247:DNA