Study On HPRT Gene Mutation Induced By Internal Radiation And γ-ray Radiation Using Cloning

Objective:To study the hypoxanthine phosphoribosyl transferase(HPRT) gene mutation of rat peripheral blood lymphocytes and spleen lymphocytes induced by intermal radiation and of human peripheral blood lymphocytes induced by Y -ray. Methods:The whole experiment include three parts.In the first part of the experiment,we studied the relationship between the HPRT gene mutation frequency(MF)of rat peripheral blood lymphocytes and the dose or dose rate of internal exposure to late fission products.In the second part of the experiment,the relationship between the HPRT gene MF of rat spleen lymphocytes and the dose or dose rate of internal exposure to late fission products was studied.For different accumulated dose groupsrthe late fission products were injected into the bodies of rats through the tail vein(The control group were injected with normal saline),then 3 9 15 and 21 days later ,the blood were sampled by the method of cardiac puncture and the spleen lymphocytes were obtained by scrubbing the spleen.Using cloning method, we got the MF of the HPRT gene.For different dose rate groups:The late fission products with specific activity were injected into four groups of rats.When the accumulated dose were nearly equal(about 12.5cSv),we sampled the blood and the spleen lymphocytes.Then we got the MF of HPRT gene by the same way as above.In the third part ,the blood,donated by a healthy man,were seperated into 5 groups with equal amount.After fourgroups exposed to different dose of ray,the MF of HPRT gene for each groups were got. Result:ln the first part ,it showed that with the increment of the accumulative internal exposure dose,the MF of the HPRT gene rose accordingly.There is a relation between the radiation doses and the HPRT gene MF.It can be described as the following linear-quadratic model: Y = 5.1217- 1.0004D +0.0988D2, R2=0.9804 .Similarly,the relationship aslo exists between the MF and the dose rate,and the model is : y = 3.9779+0.5769D-0.0055D2 ,R2 = 0.9756 .In the second part.it aslo showed that there is a relation between the accumulative internal exposure doses and the HPRTgene MF of rat spleen lymphocytes: Y = 4.5060 + 0.5635D+ 0.0606D2, R2=0.9944.Similarly,the relationship between the MF and the dose rate can be described as the following equation: y = 2.6638+ 0.5177D-0.0008D2, R2 = 0.9942 . In the third part,the results showed that there is a linear relation between the doses of the y -ray and the HPRT gene MF of human peripheral blood lymphocytes.lt can be described as the following equation: Y=0.0469+1.5316D,R2=0.9908. ConcIusioir.From the results of the study,it can be concluded that the cloning is a good method to detect the mutation of the HPRT gene induced by the internal or external radiation .The dose-effect is relatively ideal,and the HPRT gene mutation can be taken as a radiation biological dosimeter.