摘要
作为主要的重金属污染物,镉(Cd^2+)和铅(Pb^2+)对生物体具有不同影响和毒作用机制,然而当它们同时存在于机体内常会表现出不同的联合效应,因此研究以上两种重金属的联合作用极其重要。本研究以模式生物黑腹果蝇(Drosophilamelanogaster)为研究对象,采用原子吸收、发育实验、酶学测定以及荧光定量PCR评估Cd^2+和Pb^2+以及二者联合对果蝇的影响。向果蝇分别饲喂不同剂量的Cd^2+(0.05、0.1、0.3、0.5 mmol·L^-1)和Pb^2+(0.2、0.5、1.5、2.9 mmol·L^-1)以及Cd^2++Pb^2+(0.05+0.2、0.1+0.5、0.3+1.5、0.5+2.9 mmol·L^-1),测定果蝇成虫体内Cd^2+和Pb^2+积累量,以及化蛹率、羽化率、抗氧化能力、金属硫蛋白(metallothionein,MTNs)和谷胱甘肽S转移酶(glutathione S-transferase,GST)基因的表达水平。结果表明,果蝇中Cd^2+和Pb^2+浓度随着培养基中重金属浓度的上升而增加,当同时加入Cd^2+和Pb^2+后,二者积累量进一步增加。单独添加Pb^2+(0.2、0.5、1.5、2.9 mmol·L^-1)或共同添加Cd^2++Pb^2+(0.1+0.5、0.3+1.5、0.5+2.9 mmol·L^-1)显著降低果蝇化蛹率和羽化率,而Cd^2++Pb^2+联合处理较单独Cd^2+/Pb^2+处理表现出更强的效果,且这种效果随着Cd^2+/Pb^2+浓度的增加而增强。Cd^2++Pb^2+处理CAT活性较单独Cd^2+/Pb^2+处理显著提高。Cd^2++Pb^2+(0.05+0.2、0.1+0.5、0.3+1.5 mmol·L^-1)处理组SOD活性较单独Cd^2+/Pb^2+处理,SOD活性无明显变化,但在Cd^2++Pb2(+0.5+2.9 mmol·L^-1)处理组中SOD活性显著上升;Cd^2++Pb^2+(0.05+0.2 mmol·L^-1)处理组MDA含量较单独Cd^2+/Pb^2+处理显著提升,但在处理组Cd^2++Pb^2+(1+0.5、0.3+1.5、0.5+2.9mmol·L^-1)中MDA含量反而较单独的Cd^2+/Pb^2+处理有所下降。荧光定量PCR结果表明,在Cd^2+/Pb^2+处理下MTNs和Gsts表达水平显著升高。本研究表明重金属联合作用会对生物体产生不同的毒性效应,而MTNs和Gsts两类基因在生物体重金属胁迫下的解毒机制中发挥着至关重要的作用。
As the main heavy metal pollutant,Cd^^2+and Pb^2+have different effect and toxic effects on organisms,however they have a joint effect when they exist simultaneously on organisms.So it is extremely important to study the joint actin of the two heavy metals.In this study,the model organism Drosophila melanogaster was used as the research object,the effects of Cd^2+,Pb^2+and their joint action on D.melanogaster were evaluated by atomic absorption,developmental experiments,enzymatic activity determination and real-time quantitative PCR.After feeding D.melanogaster with different doses of Cd^^2+(0.05,0.1,0.3,0.5 mmol·L^-1),Pb^2+(0.2,0.5,1.5,2.9 mmol·L^-1),and Cd^2++Pb^2+(0.05+0.2,0.1+0.5,0.3+1.5,0.5+2.9 mmol·L^-1),the accumulation of Cd^2+and Pb^2+in the body,as well as the pupation rate,emergence rate,anti-oxidative capacity,expression levels of metallothionein(MTNs)and glutathione S-transferase(GST)genes,were measured.The results showed that the concentration of Cd^^2+and Pb^2+in D.melanogaster increased with the increase of heavy metal concentration in the medium.When Cd^^2+and Pb^2+were jointly supplemented,the accumulation of Cd^^2+and Pb^2+further increased.The supplementation of Pb^2+(0.2,0.5,1.5,2.9 mmol·L^-1)alone and joint supplementation of Cd^2++Pb^2+(0.1+0.5,0.3+1.5,0.5+2.9 mmol·L^-1)significantly reduced the rate of pupation and emergence,also Cd^2++Pb^2+joint treatment had a stronger effect than that of Cd^2+or Pb^2+alone.Moreover,the effect also increased with the increase of Cd^2+/Pb^2+concentration.The joint supplementation of Cd^2+and Pb^2+in each treatment group significantly increased CAT activity compared with Cd^^2+or Pb^2+treatment alone.In the treatment groups of Cd^2++Pb^2+(0.05+0.2,0.1+0.5,0.3+1.5 mmol·L^-1),the joint supplementation of Cd^2+and Pb^2+was compared with Cd^2+or Pb^2+alone,and the activity of SOD was not significantly changed,however the activity of SOD significant increased in the treatment group of Cd^2++Pb^2+(0.5+2.9 mmol·L^-1).The joint supplementation of Cd^2+and Pb^2+significantly increased the MDA content compared with Cd^2+or Pb^^2+alone in the treatment group of Cd^2++Pb^2+(0.05+0.2 mmol·L^-1),but decreased the MDA content in the treatment groups of Cd^2++Pb^2+(1+0.5,0.3+1.5,0.5+2.9 mmol·L^-1)compared with the Cd^2+or Pb^2+treatment alone.The results of real-time quantitative PCR showed that the expression levels of MTNs and Gsts genes were significantly increased after Cd^2+/Pb^2+treatment.This study showed that the joint treatment of heavy metals can produce different toxic effects on organisms,while regulation of the expression of the two types of genes,MTNs and Gsts genes,playes a crucial role in the detoxification of organisms under heavy metal stress.
作者
王博
张春红
林欣大
WANG Bo;ZHANG Chunhong;LIN Xinda(Academy of Chinese Medical Sciences,Zhejiang Chinese Medical University,Hangzhou 310053 ,China;College of Life Sciences,China Jiliang University,Hangzhou 310018 ,China)
出处
《生态环境学报》
CSCD
北大核心
2019年第5期990-998,共9页
Ecology and Environmental Sciences
基金
国家自然科学基金项目(31071297)
关键词
镉
铅
黑腹果蝇
抗氧化能力
金属硫蛋白
谷胱甘肽S转移酶
Cd
Pb
Drosophila melanogaster
anti-oxidative capacity
metallothionein
glutathione S-transferase
