Ref ID : 3941
Anthony T. Soldo, S.A. Brickson, and F. Larin; The Kinetic and Analytical Complexities of the DNA Genomes of Certain Marine and Fresh-Water Ciliates. J.Protozool. 28(3):377-383, 1981
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We investigated the macronuclear DNA genomes of several marine and fresh-water ciliates. The marine forms studied were: Uronema nigricans, Parauronema virginianum, Parauronema acutum, and two strains of Miamiensis avidus; the fresh-water ciliates included: Tetrahymena pyriformis, Paramecium octaurelia, and P. caudatum. The organisms were cultured axenically and the DNA extracted from isolated and purified macronuclear preparations. Reassociation rate constants of purified DNA preparations used to calculate kinetic complexity were determined both optically and by hydroxyapatite chromatography. Analytical complexity was determined chemically. Ciliate macronuclear DNA appeared to reassociate as a sigle unique sequence, except for a small fraction (4% of the total DNA) that was repetitive and renatured rapidly. Values for the kinetic complexities of macronuclear DNA in these forms varied over a relatively narrow range, from 1.5 to 3.8x10E10 daltons, and were only 7-15 x larger than that of the bacterium Escherichia coli. On the other hand, values of analytical complexities of macronuclear DNA of marine and fresh-water ciliates varied over two orders of magnitude and were related to the size of the animals. It is suggested that ploidy levels of macronuclear DNA in these ciliates may represent a functionally permanent amplification of the genome.