Goodrich-Young C, Krider H M
Department of Molecular Genetics and Cell Biology, University of Connecticut, Storrs 06269-2131.
Genetics. 1989 Oct;123(2):349-58. doi: 10.1093/genetics/123.2.349.
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.
在多线染色体形成过程中（复制优势），最初是在黑腹果蝇中观察到仅一个核仁组织区的核糖体DNA互补序列的复制。在此，我们证明了在拟果蝇以及黑腹果蝇/拟果蝇种间杂种中存在复制优势。在种间杂种的二倍体组织中观察到了第二种核仁现象，即核仁显性。在这种情况下，两个核仁组织区中只有一个形成核仁。然而，消除核仁显性的X染色体异染色质重组对复制优势的表达没有明显影响。这些观察结果使我们得出结论，核仁显性和复制优势是影响核糖体DNA的可操作分离的功能，并且可能由不同的调节事件决定。
