Comparative genome mapping of experimental animals by FISH

荧光原位杂交（FISH）是一种将克隆DNA探针直接定位于中期染色体上的有效技术。本研究将直接R-显带FISH技术应用于人类和小鼠的基因组作图，建立了高分辨率的系统遗传学作图系统，并对大鼠、叙利亚仓鼠和臭鼩（Suncus murinus）等缺乏作图的实验动物进行了研究。DNA克隆在复制型R带染色体上的杂交效率足以定位所有物种的小片段cDNA克隆和基因组DNA克隆，FISH方法的优点是可以将小鼠和人的cDNA探针直接定位到不同物种的染色体上。我们尝试用小鼠和人的cDNA克隆对大鼠和叙利亚仓鼠的功能基因进行染色体定位，以构建这些物种的比较基因组图谱。我们将70和46个基因分别定位到大鼠和叙利亚仓鼠染色体上，我们可以在小鼠13号染色体和大鼠1号染色体之间确定一个新的同线区域，在小鼠和叙利亚仓鼠染色体之间确定17个新的同线区域。我们还用人、小鼠和大鼠的cDNA克隆将三个功能基因定位到Suncus染色体上，用21个小鼠X染色体特异性cDNA克隆进行比较定位，发现小鼠和大鼠X染色体之间至少有两个染色体倒位。这一结果表明，小鼠与其他啮齿类物种的比较基因组图谱对于研究啮齿类物种进化过程中的基因组重排是非常有用的

Fluorescence in situ hybridization (FISH) is an effective technique for localization of cloned DNA probes directly onto metaphase chromosomes. Human and mouse genome mapping using FISH has been significantly enhanced by development of new techniques, especially high-resolution gene mapping with direct R-banding FISH.In this study we applied direct R-banding FISH to some map-poor experimental animals, rat, Syrian hamster and Suncus murinus, and established high-resolution sytogenetical mapping system for construction of genome map in these species. The hybridization efficiency of DNA clones on the replication R-banded chromosomes was sufficient for mapping of small sizes of cDNA clones and genomic DNA clones in all the species.The advantage of FISH method allows direct mapping of mouse and human cDNA probes to choromosomes of different species. We tried chomosome mapping of functional genes in rat and Syrian hamster using mouse and human cDNA clones to construct comparative genome map in these species. We mapped 70 and 46 genes to rat and Syrian hamster chromosomes, respectively, and we could identified a new syntenic region between mouse Chromosome 13 and rat Chromosome 1, and new 17 syntenic regions between mouse and Syrian hamster chromosoes. We colud also map three functional genes to Suncus chromosomes with human, mouse and rat cDNA clones.We found at least two chromosome inversions between mouse ans rat X chromosomes by comarative mapping with 21 mouse X chromosome-specific cDNA clones. This result suggests that comparative genome mapping between mouse and other rodent species is very useful to study genomic rearrangement on the process of evolution in the rodent species