Cesium chloride centrifugation of each of the DNAs extracted from eight strains of Crithidia revealed a main band at ρ = 1.717 g/cm3 and a satellite band varying from ρ = 1.701 to 1.705 g/cm3 for the different strains By electron microscopy each DNA was shown to include circular molecules, 0.69–0.80 µ in mean contour length, and large, topologically two-dimensional masses of DNA in which the molecules appeared in the form of rosettes. DNA isolated from kinetoplast fractions of Crithidia acanthocephali was shown to consist of light satellite DNA and to be mainly in the form of large masses, 0.8 µ (mol wt = 1.54 x 106 daltons) circular molecules, and a few long, linear molecules. The results of experiments involving ultracentrifugation, heating, and quenching, sonication, and endodeoxyribonuclease digestion, combined with electron microscopy, are consistent with the following hypothesis. The large DNA masses are associations of 0.8 µ circles which are mainly covalently closed. The circles are held together in groups (the rosettes) of up to 46 by the topological interlocking of each circle with many other circles in the group. A group of circles is attached to an adjacent group by one or more circles, each interlocking with many circles of both groups. Each of the associations comprises, on the average, about 27,000 circles (total mol wt ≃ 41 x 109 daltons). A model is proposed for the in situ arrangement of the associations which takes into consideration their form and structure, and appearance in thin sections
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August 01 1972
THE FORM AND STRUCTURE OF KINETOPLAST DNA OF CRITHIDIA
Hartmut C. Renger,
Hartmut C. Renger
From the Division of Biology, Kansas State University, Manhattan, Kansas 66502 and the Department of Biology, University of Utah, Salt Lake City, Utah 84112.
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David R. Wolstenholme
David R. Wolstenholme
From the Division of Biology, Kansas State University, Manhattan, Kansas 66502 and the Department of Biology, University of Utah, Salt Lake City, Utah 84112.
Search for other works by this author on:
Hartmut C. Renger
From the Division of Biology, Kansas State University, Manhattan, Kansas 66502 and the Department of Biology, University of Utah, Salt Lake City, Utah 84112.
David R. Wolstenholme
From the Division of Biology, Kansas State University, Manhattan, Kansas 66502 and the Department of Biology, University of Utah, Salt Lake City, Utah 84112.
Dr. Renger's present address is the Department of Pathology, New York University School of Medicine, New York 10016.
Received:
September 28 1971
Revision Received:
April 25 1972
Online ISSN: 1540-8140
Print ISSN: 0021-9525
Copyright © 1972 by The Rockefeller University Press
1972
J Cell Biol (1972) 54 (2): 346–364.
Article history
Received:
September 28 1971
Revision Received:
April 25 1972
Citation
Hartmut C. Renger, David R. Wolstenholme; THE FORM AND STRUCTURE OF KINETOPLAST DNA OF CRITHIDIA . J Cell Biol 1 August 1972; 54 (2): 346–364. doi: https://doi.org/10.1083/jcb.54.2.346
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