Table 1.

Important Steps in Study of Mitochondrial Genome

Year	Event
1949	Slonimski and Ephrussi isolated yeast mutants which were defective for cell respiration and hypothesized presence of some non-Mendelian genetic characters (Ephrussi 1949).
1960	Chevremont demonstrated that mitochondria incorporated tritiated thymidine, a marker nucleoside: nucleic acid metabolism in mitochondria (Chevremont 1960).
1962	Nass and Nass demonstrated by morphological studies that mitochondria contained DNA (Nass MM and Nass S 1962).
1965	Saccone et al. showed that isolated mitochondria were able to synthesize RNA (Saccone et al. 1965).
1965	Kroon demonstrated that intact mitochondria or fragments could incorporate amino acids, signaling presence of a protein translation system in organelle (Kroon 1965).
1967	Clayton DA and Vinograd J isolated circular dimer and concatenate forms of mtDNA in human cancer cell lines (Clayton and Vinograd 1967).
1974	Bogenhagen and Clayton revealed multicopy state of mtDNA in human and mouse cells (Bogenhagen and Clayton 1974).
1974	Berk AJ and Clayton DA clarified several features of mtDNA replication in mouse cells, including its asymmetry in time and space (Berk and Clayton 1974).
1975	First complete mitochondrial genomes cloned by Chang et al. (1975).
1981	First complete genome, belonging to human, was sequenced by Anderson et al. Bibb and Clayton sequenced mouse mtDNA (Anderson et al. 1981; Bibb et al. 1981).

Note.—Table summarizes the main scientific contributions that have clarified some structural and metabolic features of mitochondrial genomes, until first sequencing experiments (1980s).