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. Author manuscript; available in PMC: 2009 Dec 1.
Published in final edited form as: Mitochondrion. 2008 Aug 12;8(5-6):358–366. doi: 10.1016/j.mito.2008.07.007

Fig. 4. Mitochondrial DNA tRNA-Arg Gene Heteroplasmy.

Fig. 4

The superimposed peaks in the DNA sequencing chromatograms following the poly(A) stretch are the result of mtDNA heteroplasmy. A heteroplasmic insertion in the poly(A) tract shifts the following (3’) signals incrementally, thus resulting in the superimposed peaks. The poly(A) tract is preceded by TTTG (9817–9820) and followed by TTAA sequences. (A) The chromatograms obtained for different MRL mice show dramatic individual differences in the heteroplasmic patterns. A similar difference in heteroplasmy patterns were obtained for Swiss Webster (SW) mice, but was not as extensive in the LG/J, where one heteroplasmy pattern was observed (10 A length variant with a small addition of 9A). The B6 mtDNA showed no heteroplasmy and confirmed that the superimposing peaks are not a result of PCR and/or sequencing errors. (B) The DNA sequencing chromatograms obtained for different tissues from a single MRL mouse indicate that the level of heteroplasmy was the same among different organs of individual animals, but differed from animal to animal. Similar results were obtained for 5 other MRL mice (data not shown). The chromatograms obtained with the sequencing primer located 5’ to the poly(A) region (9665–9686) were presented. The DNA sequencing chromatograms were reversed to show the sequence as poly(A), and not the complementary poly(T).