Dünzinger Ulrich, Nanda Indrajit, Schmid Michael, Haaf Thomas, Zechner Ulrich
Institute of Human Genetics, Johannes Gutenberg University Mainz, Germany.
Trends Genet. 2005 Sep;21(9):488-92. doi: 10.1016/j.tig.2005.07.004.
In the chicken genome, most orthologues of mouse imprinted genes are clustered on macrochromosomes. Only a few orthologues are located in the microchromosome complement. Macrochromosomal and, to a lesser extent, microchromosomal regions containing imprinted gene orthologues exhibit asynchronous DNA replication. We conclude that highly conserved arrays of imprinted gene orthologues were selected during vertebrate evolution, long before these genes were recruited for parent-specific gene expression by genomic imprinting mechanisms. Evidently, the macrochromosome complement provides a better chromatin environment for the establishment of asynchronous DNA replication and imprinted gene expression later in evolution than microchromosomes.
在鸡的基因组中，大多数小鼠印记基因的直系同源基因聚集在大染色体上。只有少数直系同源基因位于微染色体组中。含有印记基因直系同源基因的大染色体区域以及在较小程度上的微染色体区域表现出DNA复制异步。我们得出结论，在脊椎动物进化过程中，远在这些基因通过基因组印记机制被用于亲本特异性基因表达之前，就已经选择了高度保守的印记基因直系同源基因阵列。显然，与微染色体相比，大染色体组为进化后期建立异步DNA复制和印记基因表达提供了更好的染色质环境。
