A study on an aberrant differentiation into chondrocytes in progressive ankylosis (ank/ank)

进行性强直（ank/ank）是小鼠常染色体隐性骨骼疾病。取ank/+和ank/ank小鼠的关节组织，石蜡包埋，H.E.染色切片，观察ank/ank小鼠关节的确切病理变化。在4周龄的ank/ank小鼠中，滑膜细胞分化为软骨细胞，软骨细胞的增殖使滑膜增厚。8周龄小鼠滑膜增厚部分钙化，关节软骨表面不规则。为了定位进行性强直的致病基因，我们用F2纯合子小鼠与其他菌株小鼠进行了15号染色体遗传标记的重组分析。在400个减数分裂中，我们在D15Mit130位点发现了6个重组，重组最少。我们将Ank位点定位在D15Mit130和D15Mit6之间的1.25 cM区域。为了缩小该区域，我们计划用BAC克隆和oligo GT引物寻找多态性标记，因为该区域没有更多的信息标记。在定位克隆的同时，进行了减法克隆。我们利用抑制减法杂交（SSH）进行克隆。结果，我们目前获得了两个阳性克隆，它们在ank/ank小鼠的组织中表达少于未受影响的小鼠。为了进一步的研究，我们仍然将cdna延伸到全长并绘制基因位点。

Progressive ankylosis (ank/ank) is an autosomal recessive skeletal disorder in mice. To investigate the precise pathological changes in the joints of ank/ank, the joint tissues were removed from ank/+ and ank/ank mice, paraffin-embedded, and examined with H.E. stained sections. In a 4 week-old ank/ank mouse, the differentiation of synovial cells into chondrocytes was seen and the synovial membrane was thickened by the proliferation of the chondrocytes. In an 8 week-old mouse, the thickened synovial membranes were partially calcified and the surface of the articular cartilage became irregular.To map the causative gene of progressive ankylosis, we analyzed the recombination events at genetic markers in chromosome 15 using F2 homozygous mice bled with the other strain mice. Of 400 meioses, we found 6 recombinations at D15Mit130 for the minimum of recombination. We assigned the Ank locus to the 1.25 cM region between D15Mit130 and D15Mit6. To narrow down the region, we plan to find polymorphic markers with BAC clones and oligo GT primers because there is no more informative marker in the region.In parallel with the positional cloning, the subtraction cloning was carried out. We took advantage of suppression subtractive hybridization (SSH) for the cloning. As a result, we obtained, at the present time, two positive clones that are expressed less in the tissues of ank/ank mice than those of unaffected mice. For the further study we sill extend the cDNAs to the full length and map the gene loci.