CONSTRUCTION OF FINE COMPARTIVE GENETIC MAPS FOR THE RAT AND IDENTIFICATION OF CAUSATIVE GENES IN NEUROLOGICAL MUTANT RATS

考虑到美国大鼠基因组测序计划的快速进展，我们在鉴定神经突变大鼠的致病基因方面做出了努力。为此，我们在突变的致病基因所在的基因组区域构建了几个精细的比较图谱。本项目研究的12个神经突变型大鼠品系如下。震颤大鼠、齐特大鼠、MV大鼠、KZC大鼠、CVD大鼠、HOB大鼠、SCR大鼠、QC大鼠、DMY大鼠、DFK大鼠、VF大鼠和FUUE大鼠。通过对震颤大鼠的定位克隆，发现天冬氨酸酰基酶基因所在的关键区域存在基因组缺失。我们发现ZI/ZI大鼠大脑中的Attractin基因表达显著减少，并确认ZI在Atrn的一个剪接供体部位有8个碱基的缺失。通过基因组和序列分析，检测到MV大鼠包括外显子1在内的基因组缺失。至于KDP大鼠，我们在reelin基因中发现了一个核苷酸插入突变，可能是零等位基因。大鼠神经突变CVD和HOB是由Netrin-1受体基因Unc5h3突变引起的。VF大鼠中枢神经系统中的异常空泡化由chR8上的一个隐性基因控制。对于SCR大鼠的白内障表型，发现了位于关键定位区域的氧化橙烯环化酶基因突变。发现了dmy和dfk大鼠的位置候选基因，并进行了详细分析。为克隆KDP大鼠IDDM/KDP-1致病基因Cblb，首次构建了大鼠和小鼠在该基因座附近的精确遗传图谱和比较图谱。为了鉴定dmy突变，我们确定了相应的基因组区域，并构建了其精细的遗传图谱和物理图谱。

Considering the rapid progress of the rat genome sequencing project in the US, we have put our efforts into the identification of causative genes in neurological mutant rats. For that reason, we constructed several fine comparative maps in genomic regions where the causative genes of the mutants are located. Twelve neurological mutant rat strains we studied in this project were as follows. Tremor rats, Zitter rats, mv rats, KZC rats, cvd rats, hob rats, SCR rats, qc rats, dmy rats, dfk rats, vf rats, and furue rats. By positional cloning for tremor rats, a genomic deletion was found within the critical region in which the aspartoacylase gene is located. We found a marked decrease in Attractin mRNA in the brain of the zi/zi rat and identified zi as an 8-bp deletion at a splice donor site of Atrn. A genomic deletion including exon 1 of the mv rats was detected by genomic and sequence analyses. As for the KDP rats, we identified a nucleotide insertion mutation, probably null allele, in the reelin gene. Rat neurological mutations cvd and hob were caused by mutations in the netrin-1 receptor gene Unc5h3. Abnormal vacuolation in the CNS of the vf rats was found to be controlled by a recessive gene on Chr8. As for the cataract phenotype in the SCR rats, a mutation of oxidosqualene cyclase gene that is located in the critical mapping region was found. Positional candidate genes for dmy and dfk rats were found and analyzed in detail. To clone the causative gene Cblb of Iddm/kdp 1 in KDP rats, a precise genetic and comparative map of rat Chr11 and mouse Chr16 in the vicinity of the locus was first constructed. Toward the identification of the dmy mutation, we determined the corresponding genomic region on mouse Chr13 and constructed its fine genetic and physical maps.