Electronic Resource
Oxford, UK
:
Blackwell Publishing Ltd
The @journal of eukaryotic microbiology
21 (1974), S. 0
ISSN:
1550-7408
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
SYNOPSIS. The results of physiochemical and electron microscope studies on the structure of the kinetoplast DNA of Crithidia are discussed. The molecular weight of isolated kinetoplast DNA is approximately 41 × 109 daltons. The basic unit of organization of this DNA is a covalently closed circular molecule 0.8 μm in contour length (molecular weight 1.54 × 106 daltons). An average of 33 such circles are held together in a group by topological interlocking of each circle with a large number of other circles in the group. An average of 804 groups are held together into a structure termed an association. A group of circles is attached to several adjacent groups. This is accomplished by 1 or more circles each interlocking with many circles in 2 (but never more) of the groups. The groups of circles are arranged in such a way that the association, comprising about 27,000 circles, has a topologically 2-dimensional form. A model is presented for the in situ arrangement of the kinetoplast DNA association. Data which we have obtained is consistent with the view that all of the circular molecules of kinetoplast DNA of one organism carry the same genetic information. The transcription product is a single RNA molecule of approximately the size of a single circular DNA molecule. From studies involving density shift experiments using deuterium oxide, buoyant density ultracentrifugation and electron microscopy we have determined the following concerning replication of kinetoplast DNA: (a) doubling of the kinetoplast DNA results from the replication of each circular molecule rather than from extensive replication of a small number of circular molecules; (b) replication of kinetoplast DNA is a semi-conservative rather than a conservative process and there is recombination at an undefined time during the cell cycle; (c) a portion of a kinetoplast DNA association is in the form of long linear molecules during the replicative phase of that association.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1550-7408.1974.tb03716.x
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