本文叙述了由小麦染色体上分离得到的两个新的转座因子。它们的结构与由RNA中间体为模板,通过反转录酶复制的反转座子相似。这些因子对染色体的结构及其变异意义重大。我们还对最近了解到的rRNA基因表达如何调控和核仁显性的起源进行了总结。本文还概述了基因调控模型的内含,即调控模型是通过启动因子(transacting factors)识别模型中的调节DNA序列的。 This article describes two new transposable elements isolated from wheat chromosomes. Their structure is similar to the retrotransposons replicated by reverse transcriptase using RNA intermediates as templates. These factors have significant implications for the structure and variation of chromosomes. We also summarize the recent understanding of how rRNA gene expression is regulated and the origin of nucleolar dominance. The article also summarizes the implications of the gene regulatory model whereby regulatory sequences identify regulatory DNA sequences in the model through transacting factors.