Delany Mary E, Robinson Charmaine M, Goto Ronald M, Miller Marcia M
Department of Animal Science, University of California, Davis, CA 95616, USA.
J Hered. 2009 Sep-Oct;100(5):507-14. doi: 10.1093/jhered/esp044. Epub 2009 Jul 17.
Here we present a high-resolution cytogenomic analysis of chicken microchromosome 16. We established the location of the major histocompatibility complex (MHC)-B and -Y subregions relative to each other and to the nucleolus organizer region (NOR) encoding the 18S-5.8S-28S ribosomal DNA. To do so, we employed multicolor fluorescence in situ hybridization using large-insert bacterial artificial chromosome clones with fully sequenced inserts or repetitive sequence probes specific for the subregion of interest. We show that the MHC-Y and -B regions are located on the same side of the NOR, rather than opposite ends, as previously proposed. On the q arm, the MHC-Y is closely adjacent to the NOR, whereas the MHC-B is distal near the q-terminus. A relatively large GC-rich region separates the 2 MHC subregions and includes a specialized structure, a secondary constriction. We propose that the GC-rich large physical distance is the basis for the lack of genetic linkage between the NOR and MHC-B and between the MHC-Y and -B. An integrated model for GGA 16 is presented that incorporates gene complex order in the context of key architectural features including p and q arms, primary (centromere) and secondary constrictions, telomeres, as well as AT- and GC-rich regions.
在此，我们展示了对鸡微染色体16的高分辨率细胞基因组分析。我们确定了主要组织相容性复合体（MHC）-B和-Y亚区相对于彼此以及与编码18S-5.8S-28S核糖体DNA的核仁组织区（NOR）的位置。为此，我们使用了多色荧光原位杂交技术，采用带有完全测序插入片段的大插入细菌人工染色体克隆或针对感兴趣亚区的重复序列探针。我们发现，MHC-Y和-B区域位于NOR的同一侧，而不是如先前提出的位于相反两端。在q臂上，MHC-Y紧邻NOR，而MHC-B在靠近q末端的远端。一个相对较大的富含GC的区域将这两个MHC亚区隔开，并且包含一个特殊结构，即一个次缢痕。我们提出，富含GC的大物理距离是NOR与MHC-B之间以及MHC-Y与-B之间缺乏遗传连锁的基础。本文提出了一个GGA 16的整合模型，该模型在包括p和q臂、主缢痕（着丝粒）和次缢痕、端粒以及富含AT和GC的区域等关键结构特征的背景下纳入了基因复合体顺序。
