Regulation of Macronuclear DNA Content inTetrahymena thermophila*†
作者:
F. P. DOERDER,
期刊:
The Journal of Protozoology
(WILEY Available online 1979)
卷期:
Volume 26,
issue 1
页码: 28-35
ISSN:0022-3921
年代: 1979
DOI:10.1111/j.1550-7408.1979.tb02726.x
出版商: Blackwell Publishing Ltd
关键词: Index Key Words:Tetrahymena thermophila; cell cycle; macronuclear DNA; computer simulation.
数据来源: WILEY
摘要:
Synopsis.Unequal macronuclear division inTetrahymena thermophilaintroduces variance into G1 macronuclei; unless eliminated such variance would result in continuous variation in DNA content. Analysis of G1 and G2 macronuclear variances reveals that the added variance is eliminated by action on the extremes of macronuclear DNA content. In this model (Model II), macronuclei with small amounts of DNA have an additional complete S phase, while those with large amounts of DNA skip S. From available data, chromatin extrusion is shown not to contribute significantly, if at all, to the elimination of variance. Computer simulations utilizing haploid subunits indicate that model II predictions apply reasonably well to experimental data in terms of coefficients of variation, mean DNA content, and frequency of additional and skipped S phases. The simulations reveal also that within certain constraints, particularly the thresholds for additional and skipped S phases, macronuclear assortment is unaffected by Model II regulation. The relationships between Model II and other aspects of the cell cycle are briefly discussed.
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