Open AccessReplicating, Covalently Closed, Circular DNA from Kinetoplasts of Trypanosoma cruzi
Author(s) -
Ch. Brack,
Etienne Delain,
G Riou
Publication year - 1972
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.69.6.1642
Subject(s) - kinetoplast , ethidium bromide , dna , dna replication , biology , rolling circle replication , biophysics , trypanosoma cruzi , circular dna , minicircle , microbiology and biotechnology , genetics , genome , gene , parasite hosting , world wide web , computer science
WhenTrypanosoma cruzi are treated with Berenil, a trypanocide, their kinetoplast DNA contains an increased proportion of double-branched circular molecules. These replicating molecules have closed-circular template strands; their decrease in density when complexed by ethidium bromide in a cesium chloride gradient is proportional to the length of the replicated segments. Replication seems to be blocked at specific points, which are equidistantly spaced along the circular kinetoplast DNA molecules. Analysis of about 800 replicating forms showed that the lengths of the replicated branches are not distributed at random, but into several populations, which correspond to multiples of 15% of the total contour length of 0.5 μm. This distribution evokes a discontinuous replication process. The problem of whether kinetoplast DNA is synthesized by successive replication units, or whether and how Berenil might induce specific blocking of DNA replication, is discussed.