Characterization and mapping of mitochondrial ribosomal RNA and mitochondrial DNA in Drosophila melanogaster

Abstract

We report the isolation and some properties of the mitochondrial ribosomal RNA (mt-rRNA) of Drosophila melanogaster, and a restriction map of the mtDNA of this organism which shows the position of the rRNA genes and of the A + T-rich region in the DNA. The mt-rRNAs are about 860 and 1500 nucleotides long and have the unusual composition of about 20% G+C. Some 25% of the mtDNA is very rich in A+T and is visualized as a contiguous early melting region in denaturation mapping. We mapped the three cleavage sites of the restriction endonuclease Hae III and the four sites of Hind III on mtDNA relative to each other and relative to the early melting region. The rRNA genes have been positioned on this map. The two rRNA genes are next to each other, separated by a gap of about 160 bases. We determined the polarity of the rRNA molecules: transcription proceeds in the direction small-to-large rRNA. Despite great divergence in nucleotide composition and sequence, the properties of mt-rRNA and the arrangement of mt-rRNA genes are very similar in Drosophila and vertebrate animals.