HgCl_2对斑马鱼SOD,AChE酶活性和基因相对转录量的影响

Toxic Effects of HgCl_2 on SOD and AChE of Activities and Gene Transcription of Zebrafish

以HgCl2为实验毒物,研究其对斑马鱼的毒性效应,经染毒后,分别在第1天和第7天取斑马鱼的肌肉测定超氧化物歧化酶(SOD)、乙酰胆碱酯酶(AChE)活性,半定量RT-PCR检测肌肉中乙酰胆碱酯酶、细胞色素P450(CYP1A)和超氧化物歧化酶(Cu/Zn-SOD)基因的相对转录量。结果显示HgCl2对斑马鱼的毒性很强,低浓度染毒1d后,基因转录量显著变化,而酶活性7d后才有显著变化。HgCl2对斑马鱼96h-LC50为244.06μg·L-1;AChE活性和基因相对转录量在第1天呈下降趋势;第7天,酶活性依然下降,但基因相对转录量在低、中浓度组呈上升趋势;高浓度组呈下降趋势,和对照组相比差异显著。SOD活性第7天表现促进作用,与染毒浓度成正相关,并有显著性差异;Cu/Zn-SOD基因转录量第1天总体呈下降趋势,第7天低浓度HgCl2对Cu/Zn-SOD基因转录量有诱导作用,高浓度有抑制作用。CYP1A基因相对转录量第1天整体呈下降趋势;第7天呈现出低浓度升高,中、高浓度降低的变化规律。以上结果说明基因转录水平的变化比其蛋白翻译水平的变化出现更早,更灵敏,因此可作为环境污染物的早期预警;同时说明污染物对生物大分子的影响比较复杂,受多种因素调控。

Acute toxicity tests(96 h) were conducted in static-renewal aquarium systems to determine the lethal toxic effect of HgCl2 on fish.Zebrafish were exposed in HgCl2 with various levels.Superoxide dismutase(SOD) and acetylcholinesterase(AChE) activities were measured after 1 and 7 d.Muscle RNA was also extracted for semi-quantitative RT-PCR determination of AChE,CYP 1A,Cu/Zn-SOD transcription amounts.It showed that HgCl2 was highly toxic on zebrafish.Specifically,the enzymatic activities and the gene transcription amount significantly changed after 1 d and 7 d exposure in low concentration HgCl2,respectively.96h-LC50 of HgCl2 to zebrafish was 244.06 μg·L-1.AChE activity decreased on 1 d and 7 d.AChE transcription decreased on 1 d,while it increased in low and middle concentration group,decreased in high concentration group on 7 d exposure.The difference was significant compared with the control group.Until 7 d,SOD activity was promoted by HgCl2 showing a dose-response effect.The transcription of Cu/Zn-SOD decreased on 1 d,showing stimulation effect at low HgCl2 concentration and inhibition effect at high HgCl2 concentration.CYP 1A showed similar response to the transcription of Cu/Zn-SOD.In conclusion,gene transcription changed earlier than the expression of protein,which can be used as an early warning for environmental risk assessment.Also it shows that the impact of pollutants on biological macromolecules is complex.