氧化乐果对斑马鱼的毒性作用及生物富集性研究

Toxicity and Bioaccumulation of Omethoate in Danio rerio

为研究斑马鱼（Danio rerio）作为有机磷农药指示生物的可能性,以斑马鱼为实验对象,采用半静态法,研究浓度为0、2.5、5.0、7.5、10.0 mg/L的氧化乐果对斑马鱼体内蛋白质含量及乙酰胆碱酯酶（Ach E）和过氧化物酶（POD）活性的影响及其对0、2、4、6、8、10 mg/L氧化乐果7 d的富集系数（即BCF7 d）,探究氧化乐果对斑马鱼的毒性作用及其生物富集性。结果显示,氧化乐果对斑马鱼的96 h半数致死浓度（LC50）为31.57 mg/L,在1～100mg/L之间,属于高毒药物;蛋白质含量总体表现为先升高、再下降的趋势;Ach E活性受到抑制,总体表现为下降趋势;POD活性表现为诱导-抑制效应;BCF7 d随浓度的增加而减小,为1.54～5.80,且BCF7 d随Ach E活性的降低而降低,毒性作用越大,斑马鱼对氧化乐果的富集作用越弱。研究表明,蛋白质含量和乙酰胆碱酯酶活性与氧化乐果浓度有显著的剂量-效应关系,斑马鱼可以作为有机磷农药污染的指示生物。

Due to extensive use of pesticides in agriculture,aquatic ecosystems are suffering from pesticide pollution and the problem of pesticide residues has attracted attention. Omethoate is a highly toxic organophosphorus pesticide that not only affects enzyme activity in aquatic flora and fauna,but also accumulates in plants and animals and can affect animals and humans high on the food chain. To easily and quickly determine if water has been polluted by organophosphorus pesticides,a static bioassay method was used to study the toxic effects of omethoate on Danio rerio and its bioaccumulation was investigated. The study provides theoretical evidence and data to support environment monitoring and development of environmental standards. Healthy Danio rerio of body length of（ 2. 5 ±0. 2） cm and body weight（ 0. 2 ± 0. 05） g were exposed to different omethoate concentrations（ 0,2. 5,5. 0,7. 510. 0 mg / L） with one replicate for each treatment and ten fish in each group. Test duration was five days and solutions were changed each day. The protein content,acetylcholinesterase（ Ach E） and peroxidase（ POD） activities of Danio rerio were determined on days 1,3 and 5. Under the same conditions,the seven day bioconcentration factors（ BCF7 d） of omethoate in Danio rerio were determined after a 7 day exposure to omethoate at concentrations of0,2,4,6,8,10 mg / L. The 96 h LC50 of omethoate to Danio rerio is 31. 57 mg / L,in the range of 1- 100 mg / L for highly toxic substances according to the chemical toxicity scale for fish acute toxicity. The protein content of Danio rerio increased with time at omethoate concentrations of 2. 5 and 5. 0 mg / L and decreased at concentrations of7. 5 and 10. 0 mg / L. Ach E activity was inhibited by omethoate,decreasing with concentration and time. POD activity was induced by the two lower omethoate concentrations and inhibited by the two higher concentrations. BCF7 d in Danio rerio decreased with omethoate concentration,ranging from 1. 54 to 5. 80. BCF7 dalso decreased with decreasing Ach E activity,indicating that omethoate toxicity decreases bioaccumulation in Danio rerio. In conclusion,the protein content and Ach E activity of Danio rerio display a dose-response relationship with omethoate. Thus,Danio rerio can be used as a biological indicator of organophosphorus pesticide polluted water. The result provides a rapid and accurate method to determine organophosphorus pesticide polluted waters.