一种大规模的基因沉默现象——核仁显性

One Large Scale of Gene Silencing,Nucleolar Dominance

基因沉默是生物体内的一种普遍现象。在异源多倍体和远缘杂种体内,遗传物质的加倍或大量外源遗传物质的进入不但引入了大量的基因,还严重地破坏了生物体原有的遗传平衡。因此,在多倍体和远缘杂种体内,基因沉默现象就表现得尤为显著。由于来自双亲基因组的核仁组织区(NOR)在杂种细胞内存在转录竞争,致使只有来自一个亲本基因组的NOR得以转录,而来自另一亲本基因组的NOR不被转录,出现核仁显性。核糖体RNA(rRNA)基因沉默的机制和rRNA基因沉默非随机性的原因(决定NOR竞争能力的机制)一直是研究者关注的焦点。

Gene silencing was common in biology and it was happened with higher frequency in allopolyploids and hybrids because a lot of genes came into one cell from other species and the genetic balance was broken. Nucleolar organizing region （NOR） of unique genome was transcribed and that from the other genome was not because of the competition between NORs of the genomes from the two parents, and the phenomenon was nucleolar dominance. The mechanism of ribosome RNA gene silencing was attended and the processes were reviewed in the present paper.