Molecular Biology of the Gene Expression of Hard Tissue Forming Cells

(1)牛釉原蛋白基因在X和Y染色体上均有表达，定位于X和Y染色体上。为了研究牛釉原蛋白Y染色体基因在转录水平上的表达，从雄性和雌性牛胎牛肝脏和牙胚中分离了染色体DNA、信使RNA和釉蛋白。已知Y染色体釉原蛋白基因缺失21个氨基酸结构域，相对于X衍生釉原蛋白基因。RT-PCR产物在琼脂糖凝胶上有两条带。雌性的只有一条带，表明Y染色体上的釉原蛋白基因具有转录活性。男性的无细胞翻译产物和釉质蛋白都比女性的有更多的复杂斑点，这些结果表明Y染色体上的牛釉原蛋白基因是活性的，并产生男性特有的釉原蛋白。(2)原位杂交…观察牙齿移动过程中牙槽骨改建更加城市化。-I型胶原和骨涎蛋白mRNAs的表达-I型胶原和骨涎蛋白(BSP)mRNAs在牙齿移动时牙槽骨中的表达。在适当的移动天数后，将组织标本脱钙并切成石蜡切片。用原位杂交法检测mRNAs的表达。在生理性牙齿移动的标本中，沿矿化方向的成骨细胞和邻近的根间隔骨细胞(IRS)都有高水平的表达。结果表明，BSP基因的表达和胶原蛋白的表达不仅与生理性骨重建的矿化有关，而且与正畸力诱导的成骨细胞活化的过程有关。较少

(1) The Bovine Amelogenin Genes Are Expressed from Both the X and the Y Chromosomes.The bovine amelogenin genes are localized to X and Y chromosomes. To investigate the expression of bovine amelogenin Y-chromosomal gene at the transcription levels., chromosomal DNAs, messenger RNAs and enamel proteins were isolated from male and female fetal bovine liver and tooth germ. It was known that 21-amino acid domain was deleted in the Y-chromosomal amelogenin gene, relative to the X-derived amelogenin. The RT-PCR products from male mRNA had two bands on agarose gel. while those from female had one band, indicating Y-chromosomal amelogenin gene was transcriptionally active. Both cell-free translation products and enamel proteins from male had more complex spots than those from female.These results indicate that the bovine amelogenin gene on Y-chromosome is active and produces male speciffic amelogenin.(2) Observation of Alveolar Bone Remodeling Accompanied with Tooth Movement by in situ hybridi … More zation. -Expression of Type I Collagen and Bone Sialoprotein mRNAs-Expression of type I collagen and bone sialoprotein (BSP) mRNA in the alveolar bone accompanied with tooth movement was investigated. After the proper number of days of movement, histological speciments were decalcified and sliced into paraffin sections. The expression of mRNAs was examined by the in situ hybridization method. In the samples of physiological toothmovement, a high level of expression in both mRNAs was observed in osteoblasts along the mineralization from and adjacent osteocytes in the interradicular septum (IRS). In contrast, a low level of mRNA expression was observed on the opposite side of the IRS.In the specimens of experimental tooth movement, a high level of experssion was detected in the osteoblasts on the tension side of IRS,but negligible reaction in those on the compression side.These results suggest that BSP gene experssion as well as that of collagen are related not only to mineralization in physiological bone remodeling but also to the process by activated osteoblasts induced by orthodontic force. Less