Ref ID : 7602
Guy Metenier, Janine Dupy-Blanc, T. Njine, and C.A. Groliere; [Observations sur les Teneurs en DNA Macronucleaire des Doublets Homopolaires du Cilie Tetrahymena paravorax (Corliss, 1957)]. Protistologica XVII(4):563-571, 1981
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Homopolar doublets of Tetrahymena paravorax have 2 sets of buccal organelles, 2 contractile vacuoles and a single macronucleus. They can undergo the microstome-macrostome transformation. The "doublet microstome/singlet microstome" ratios of means of some cell parameters - cell body width, number of kineties, G1 DNA content of macronucleus, length of cell cycle, duration of the macronuclear S period - are about 1.5. While the fraction of the cycle occupied by S phase is the same in the two cell types, the one occupied by G1 phase in doublets is longer than that of singlets (~20% instead of 8%). The formation of chromatin extrusion bodies during macronuclear division occurs with a high frequency (>80%) in doublets as in singlets. With regard to macrostome forms (predators), it has been shown that, likewise in singlets, the doublets have macronuclear DNA contents extending above the G2 level. These findings are discussed with reference to the problem of regulation of macronuclear DNA content.