RESEARCH OF THE MUTATED GENE RESPONSIBLE FOR RAT OSTEOCHONDRODYSPLASIA AND INVESTIGATION OF THE EMBRYONIC PATHOGENESIS.

导致大鼠骨软骨发育不良的ocd基因位于大鼠第11号染色体上。在这项研究中，我们在强迫症位点周围绘制了一个精细的地图来识别候选基因。我们还揭示了突变大鼠在胚胎后期的发病机制。利用HGN （HGN / HGN）雌代与F1 （BNxHGN:+/ HGN）雄代的回交后代进行连锁分析。通过对与ocd位点密切相关的大鼠/仓鼠辐射杂交克隆进行分型，获得了ocd位点周围的RH图谱。在另一项连锁分析中，我们用微卫星（MS） maker对受影响的大鼠进行了基因分型，显示了该菌株的多态性。ocd基因座最终定位在大鼠chr11的100kb区。目前，有两个候选基因位于该区域。RT-PCR分析显示了这些基因在患病大鼠胎儿组织中的表达。在胚胎发病机制的实验中，我们首先证实了在改变遗传背景的回交新生儿（HGN x F1衍生）中强迫症的多效性，表明强迫症影响胎儿的多器官发育。其次，我们揭示了JCD株感染大鼠的胎儿发病机制。在胚胎日（ED） 16.5-21.5剖宫产获得胎鼠。通过对ocd位点侧翼的MS进行PCR分型。妊娠期16.5时，患儿体重明显小于正常胎儿。随着胚胎龄的增加，四肢长度的减少更为严重。alcian blue和茜素红S双染色显示，在ED 16.5时，患病胎儿的全身软骨形成已经发育不全，ED 18.5后，患病大鼠的骨化加速。组织学检查显示，ED 16.5后大鼠虽然形成了骨化中心，但软骨基质的积累较差。这些结果表明，ocd的正常等位基因可能在ED 16.5之前表达，并且该基因的正常表达对正常发育至关重要。少

The gene, ocd, responsible for rat osteochondrodysplasia is located on rat chromosome 11. In this study, we made a fine map around the ocd locus to identify the candidates. We also revealed the pathogenesis of the mutant rat during late embryonic stage. Linkage analysis was performed using backcross progeny obtained from the mating between HGN (hgn/hgn) females and F1 (BNxHGN:+/hgn) males. RH map around the ocd locus was obtained by typing Rat/Hamster radiation hybrid clones with closely related markers to the ocd locus. In another linkage analysis, we genotyped the affected rats of the OCD strain with microsatellite (MS) makers showing polymorphism in the strain. The ocd locus was finally localized into 100kb-region on rat Chr.11. At present, two candidate genes for ocd are located in the region. RT-PCR analysis revealed the expressions of these genes in the fetal tissue of the affected rats. In the experiments of embryonic pathogenesis, at first, we confirmed the pleiotropic effects … More of the ocd on the backcross newborns (derived from HGN x F1) under altered genetic background, indicating that ocd affects on the fetal development of multiple organs. At second, we revealed the fetal pathogenesis of the affected rats of JCD strain. The fetal rats were obtained from pregnant mothers by cesarean section at embryonic day (ED) 16.5-21.5. They were genotyped by the PCR of the MS flanking the ocd locus. The body weight was significantly smaller in the affected than normal fetuses at ED 16.5. The reductions of the length of the limbs became severe with increase of embryonic ages. The double-staining with alcian blue and alizarin red S revealed that systemic cartilage formation of the affected fetus was already hypoplasitc at ED 16.5 and that the ossification was accelerated in the affected rat after ED 18.5. Histological examination revealed that, although the ossification center was formed, the accumulation of cartilage matrices was poor in the affected rats after ED 16.5. These results suggnst that normal allele for ocd might be expressed before ED 16.5 and that the normal expression of the gene is critical for, normal development. Less