Demonstration of mitochondrial ribosomal RNA in frozen and paraffin–embedded sections of skeletal muscle by in situ hybridization

Abstract

We have used in situ hybridization with synthetic oligonucleotide probes to the 16S sub–unit of mitochondrial ribosomal RNA to detect mitochondrial accumulations in biopsies of skeletal muscle from 16 patients with mitochondrial myopathies. In all cases, the distribution of the hybridization signal matched the pattern of succinate dehydrogenase activity in adjacent cryostat sections. In situ hybridization also allowed visualization of mitochondrial accumulations in paraffin–embedded sections of skeletal muscle that had been fixed in either De Castro's solution or formalin. DNase pre–treatment did not significantly diminish the intensity of hybridization signal, suggesting that the hybridization is predominantly to RNA. The advantages of this technique are that it allows the investigation of mitochondrial disorders when only paraffin–embedded tissue is available and should also facilitate the demonstration of mitochondrial accumulations in tissues other than skeletal muscle.