Construction of a comparative chicken chromosome map by functional gene mapping

利用直接R-显带FISH技术，将109个鸡功能基因的DNA克隆和39个从鸡脑cDNA文库中分离的EST克隆（经NCBI数据库同源性检索确定为已知功能基因的cDNA克隆）定位到鸡染色体上。将68个基因定位在30对小染色体上，占148个基因的46%，表明鸡小染色体上功能基因的密度较高。通过鸡与人染色体图谱的比较，新发现了鸡大染色体与人染色体之间5个保守的同线区，并利用鸡染色体特异性涂染DNA探针进行比较染色体涂染，利用鸡粘粒DNA克隆和cDNA克隆进行染色体定位，构建了日本鹌鹑和珍珠鸡与鸡的比较染色体图谱。日本鹌鹑的染色体着色模式与鸡的相同，但在1、2、4和8号染色体上，日本鹌鹑的DNA克隆的染色体定位和基因顺序与鸡不同。我们指定的断点的臂间倒位在染色体1和2添加13个功能基因的定位数据，使用鸡的cDNA克隆。在8号染色体中也证实了臂间倒位的存在。在4号染色体的着丝粒区域，推测包含两个以上的重排。比较染色体分析还显示，除了两个染色体间重排外，珠鸡和鸡的大染色体具有高度保守的同源性。珍珠鸡4号染色体代表鸡9号染色体与鸡4号染色体q臂的着丝粒融合。珍珠鸡5号染色体是由鸡的6号和7号染色体融合而成。在珍珠鸡7号染色体上发现了一个臂间倒位，与鸡的8号染色体相对应。

We mapped 109 DNA clones of chicken functional genes, and 39 EST clones isolated from the cDNA library of chicken brain, which were identified as cDNA clones of known functional genes by homology search with the NCBI data base, to chicken chromosomes by direct R-banding FISH. The 68 genes that accounted for 46% of the 148 genes were mapped to 30 pairs of microchromosomes, indicating the high density of the functional genes in chicken microchromosomes. Comparing the chicken chromosome map with that of human, we newly identified five conserved syntenic regions between chicken macrochromosomes and human chromosomes.We constructed comparative chromosome maps of Japanese quail and guinea fowl to chicken by comparative chromosome painting with the chicken chromosome-specific painting DNA probes and by chromosome mapping of chicken cosmid DNA clones and cDNA clones. The chromosone painting patterns in Japanese quail were the same as those of chicken, while the chromosomal locations of the DNA clones and their gene orders in Japanese quail differed from chicken in chromosomes 1, 2, 4 and 8. We specified the breakpoints of the pericentric inversions in chromosomes 1 and 2 by adding mapping data of 13 functional genes using chicken cDNA clones. The presence of pericentric inversion was also confirmed in chromosome 8. In the centromeric region of chromosome 4, it was speculated that more than two rearrangements are contained. The comparative chromosome analysis also revealed the highly conserved homology of macrochromosomes between guinea fowl and chicken except for two inter-chromosomal rearrangements. Guinea fowl chromosome 4 represented the centric fusion of chicken chromosome 9 with the q arm of chicken chromosome 4. Guinea fowl chromosome 5 resulted from the fusion of chicken chromosomes 6 and 7. A pericentric inversion was found in guinea fowl chromosome 7, which corresponded to chicken chromosome 8.