Development of the gene deletion model rats by random mutagenesis

为了产生一些新的突变大鼠，用氯胺丁苯进行了随机诱变。为了确定最佳剂量的百菌清诱变交配时间和最佳诱变交配时间，我们统计了不同剂量的百菌清与雄性大鼠交配后所产仔鼠的数量。因此，很明显，每公斤体重5毫克到15毫克的氯氨丁腈适合服药，并且在服药后三周到六周之间进行交配是好的。雌性大鼠(G1代)是用10 mg百菌清处理的BN品系雄性大鼠与正常F344雌性大鼠杂交获得的。这只雌性老鼠有怀孕的能力。雌性大鼠(G2代)与雄性大鼠(G3代)杂交，获得雄性大鼠(G3代)。然后我们让这些老鼠杂交，得到了六只老鼠。当这六只大鼠饲养了大约一年后，其中一只大鼠患上了皮肤癌，另一只出现了糖尿病症状。据推测，这些大鼠是一些基因发生突变的突变体。此外，还观察到了身体大小约为正常大鼠30%的侏儒大鼠。在几乎所有的情况下，侏儒鼠在断奶前死亡，但也有少数侏儒鼠长到成年。虽然成年侏儒鼠能够受孕，但它们通过与正常鼠交配产生了一些侏儒鼠。采用基因芯片技术对G5代大鼠进行基因表达谱分析，以确定发生了哪些基因突变。结果证明，至少有10种基因在G5大鼠体内不表达。推测这些基因的表达受各基因缺失型突变的抑制。

Random mutagenesis with chlorambucil was performed in order to produce some new mutant rats. To identify the optimal quantity of chlorambucil and the optimal mating time for mutagenesis, we counted the number of new born rats born from female rats mated with the male rat medicated with several dose of chlorambucil. Consequently, it became clear that between 5mg and 15mg per kg weight of chlorambucil are good for medication, and it is good to perform mating between three weeks and six weeks after the medication of chlorambucil. The female (G1 generation) rat was obtained as a result of crossing between the male rat of BN strain medicated with 10mg chlorambucil and a normal F344 female rat. This female rat has the capability to conceive. A male rat (G3 generation) was obtained from a cross the female rat (G2 generation) with the male rat (G3 generation). Then we crossed these rats and obtained six rats. When these six rats were bred for about one year, one of the rats had skin cancer and another one showed diabetes symptom. It was presumed that these rats are the mutants by which mutation was occurred in some genes. In addition, the dwarfish rat whose size of the body is about 30% of a normal rat was also observed. In almost all cases, the dwarfish rats died before weaning, but a few dwarfish rats grew to the adult. Although the adult dwarfish rats was able to be conceived, they born some dwarfish rats by mating with a normal rat similarly. In order to confirm to which gene mutation has happened, gene expression analysis was performed for the G5 generation rats using DNA microarray. Consequently, it was proved that at least ten kinds of genes was not expressed in the G5 rats. These genes were presumed that the expression of these genes was suppressed by deletion type of mutation in each genes.