Genetics, Vol 123, 349-358, Copyright © 1989


INVESTIGATIONS

Nucleolar Dominance and Replicative Dominance in Drosophila Interspecific Hybrids

C. Goodrich-Young and H. M. Krider
Present address: Fred Hutchinson Cancer Research Center, 1124 Columbia Street, Seattle, Washington 98104.

The replication of the rDNA complement of only one nucleolus organizer region during polytene chromosome formation (replicative dominance) was initially observed in Drosophila melanogaster. Here we demonstrate replicative dominance in Drosophila simulans and D. melanogaster/D. simulans interspecific hybrids. A second nucleolar phenomenon, nucleolar dominance, is observed in the diploid tissue of interspecific hybrids. In this case only one of two nucleolus organizer regions forms a nucleolus. However, reorganizations of the X chromosome heterochromatin which eliminate nucleolar dominance have no apparent effect on the expression of replicative dominance. These observations lead us to conclude that nucleolar dominance and replicative dominance are operationally separable functions influencing the rDNAs, and may be determined by differing regulatory events.


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J. M. Flowers and R. S. Burton
Ribosomal RNA Gene Silencing in Interpopulation Hybrids of Tigriopus californicus: Nucleolar Dominance in the Absence of Intergenic Spacer Subrepeats
Genetics, July 1, 2006; 173(3): 1479 - 1486.
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