六价铬对g12细胞gpt位点的影响

The mutation of gpt locus in g12 cell induced by Chromium (Ⅵ)

采用改良的ｇ１２细胞代替Ｖ７９细胞，研究了六价铬［Ｃｒ（Ⅵ）］对ｇｐｔ（ｘａｎｔｈｉｎｅｇｕａｎｉｎｅｐｈｏｓｐｈｏｒｉｂｏｓｙｌｔｒａｎｓｆｅｒａｓｅ，ｇｐｔ，黄嘌呤鸟嘌呤磷酸核糖转移酶）位点的影响。结果表明，Ｋ２Ｃｒ２Ｏ７在引起细胞中毒不明显的低剂量０．６２５μｍｏｌ／Ｌ（相当于铬含量６４．９９μｇ／Ｌ）即可诱发ｇ１２细胞ｇｐｔ位点的突变，且高达本底的９倍以上；较高剂量组２．５μｍｏｌ／Ｌ诱发的６－ＴＧ（６－ｔｈｉｏｇｕａ－ｎｉｎｅ，６－巯基鸟嘌呤）突变体可达本底的５０倍以上。Ｋ２Ｃｒ２Ｏ７诱发的ｇ１２细胞ｇｐｔ位点突变在０～２．５μｍｏｌ／Ｌ的Ｋ２Ｃｒ２Ｏ７范围内，具有明显的剂量－反应关系［ｙ＝２４．２７ｘ－１．７５，ｒ＝０．９９５，ｙ为突变率（ｍｕｔａｔｉｏｎｒａｔｅ），ｘ为为Ｋ２Ｃｒ２Ｏ７剂量］。但随着Ｋ２Ｃｒ２Ｏ７的浓度增高，５．０μｍｏｌ／Ｌ的Ｋ２Ｃｒ２Ｏ７组，由于细胞存活率太低，细胞数不够，达不到最后接种要求，不易继续进行。这一现象可能与Ｋ２Ｃｒ２Ｏ７的细胞毒性有关。因此，Ｋ２Ｃｒ２Ｏ７的遗传毒性及致突变性，只是在一定的剂量范围内遵循剂量反应规律。

The gpt locus of g12 cell is very sensitive to mutagens.In this paper,g12 cells were used to evaluate the mutagenicity of (K 2Cr 2O 7).Results revealed that 0 625μmol/L K 2Cr 2O 7 could induce the mutation of gpt locus,the mutation rate was about 8 fold higher than that of background.The mutation rate of gpt locus was dose dependent ( y =24 27 x -1 75, r =0 995, y :mutation rate; x :the dose of K 2Cr 2O 7) in the narrow range of 0—2 5μmol/L K 2Cr 2O 7.When above 2 5μmol/L K 2Cr 2O 7,the seeding efficiency was too low to do the further experiment because of the high cytotoxicity of K 2Cr 2O 7.In conclusion,K 2Cr 2O 7 could display high mutagenicity only in its narrow dose range. \ \