【摘要】 以黑腹果蝇Canton-S品系为试验材料,采用镉饱和法测定重金属镉胁迫后果蝇金属硫蛋白质量比的变化,并应用实时荧光定量PCR(Real-Time PCR)方法检测了不同质量浓度镉处理后果蝇金属硫蛋白相关基因MtnB、MtnC、MtnD、MtnE及金属耐受因子Hmt-1基因mRNA水平的表达差异。结果表明,1)不同质量浓度镉处理对雌、雄果蝇均产生明显的生理影响,导致果蝇寿命缩短。镉胁迫果蝇10 d后,其半数致死质量浓度为52.0 mg/L,为后期果蝇对镉胁迫产生的解毒机制研究提供浓度设定依据。2)镉胁迫后雌、雄果蝇体内金属硫蛋白质量比显著升高,与对照组相比差异显著,并存在一定的剂量依赖性;3)镉胁迫导致黑腹果蝇金属硫蛋白相关基因mRNA水平表达上调,并具明显的剂量依赖性,同时在一定范围内Hmt-1基因的表达随镉质量浓度升高而上调,具有浓度依赖效应。更多还原

【Abstract】 The aim of this paper is to present the study results on the responsive reactions and the detoxification mechanisms of cadmium( one of the major heavy metal contaminants in the environment) in Drosophila melanogaster( Canton- S),one of the essential model organisms in biological research area. For the study purpose,we have investigated and tested the mortality of Drosophila melanogaster after being fed with Cd( 1. 875 mg/L,3. 75 mg/L,7. 5 mg/L,15. 0 mg/L,30. 0 mg/L,60. 0 mg/L,90. 0mg/L) for 10 d. The results of our testing have shown that cadmium can reduce the lifespan of Drosophila melanogaster both for males and females,with the median lethal mass concentration of Drosophila melanogaster being 52. 0 mg/L,which has resulted in a significant reference for further researches. And,then,we have made an evaluation of the metallothionein contents and the expression of different genes,namely MtnB,MtnC,MtnD,MtnE and Hmt- 1( heavy metal tolerance factor 1) in case when Drosophila melanogaster was exposed to cadmium with different mass concentrations( 6. 5 mg/L,13. 0 mg/L,26. 0 mg/L,52. 0 mg/L),with the saturation method and Real-Time PCR. The results we have gained through the tests indicate that,as compared with the control group,the metallothionein contents have shown a significant increase in the cadmium treatment groups with a dose-dependent responsive response( p < 0. 05). Besides,the expression of the metallothionein genes( MtnB,MtnC,MtnD,MtnE) tends to be significantly up-regulated,with a significant difference as compared with the control group( p < 0. 05). What is the most important for our research is that,with the increase of cadmium concentration,the expression of Hmt- 1 gene gets gradually upregulated( p < 0. 05),which is supposed to prove that Drosophila melanogaster have gained somewhat resistant power against the heavy metal toxicity by their own responsive physiological mechanisms,such as regulating the expression of metallothionein and metal tolerance factor genes to adjust steadily the aggressive state of the metal ions. Thus,the given study can be said to find an experimental opening approach to the toxicity research in molecular theory of heavy metals. At the same time,the paper can also help to assess the safety margin of the heavy metal pollutants and contaminants.更多还原