Extranuclear DNA in Polytomella Parva

When DNA was extracted from the phytoflagellate P. parva, and subjected to electrophoresis, a prominent low molecular weight band appeared at a position corresponding to 3.7 kb. The DNA was shown to be associated with mitochondrial membrane fragments and most likely exists as mitochondrial plasmids, common to many plants and fungi. The DNA molecule appears to be linear, and its susceptibility to exonuclease digestion indicates that there are no telomeres present. A Southern blot hybridization was performed with an enzymatic labeling system. The fragment hybridized with itself, but not with DNA in other portions of the gel, suggesting that the sequence of the element is not present in the larger DNA fragments.

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