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Published May 1, 1967 | public
Journal Article Open

A dye-buoyant-density method for the detection and isolation of closed circular duplex DNA: The closed circular DNA in HeLa cells


Covalently closed circular duplex DNA's are now known to be widespread among living organisms. This DNA structure, originally identified in polyoma viral DNA,(1,2) has been assigned to the mitochondrial DNA's in ox(3) and sheep heart,(4) in mouse and chicken liver,(3) and in unfertilized sea urchin egg.(5) The animal viral DNA's--polyoma, SV40,(6) rabbit(7) and human(8) papilloma--the intracellular forms of the bacterial viral DNA's φX174,(9,10) lambda,(11,12) M13,(13) and P22(14) -- and a bacterial plasmid DNA, the colicinogenic factor E2,(15) have all been shown to exist as closed circular duplexes. Other mitochondrial DNA's(16,17) and a portion of the DNA from boar sperm(18) have been reported to be circular, but as yet have not been shown to be covalently closed.

Additional Information

© 1967 by the National Academy of Sciences. Communicated by James Bonner, March 2, 1967. It is a pleasure to thank J. Huberman for providing us with the labeled HeLa cells; J. Kiger and E. T. Young, II, for their gift of closed circular lambda DNA and for allowing us to quote their unpublished analysis; G. Attardi for advice and assistance in the preparation of HeLa mitochondria; L. Wenzel and J. Eden for their assistance in the culture of the polyoma virus; R. Watson for his several technical contributions; and R. Kent for assistance in the preparation of the manuscript. This work was supported in part by grants HE 03394 and CA 08014 from the U.S. Public Health Service and by fellowships from the U.S. Public Health Service and the National Science Foundation.


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