Abstract
Endosulfan has been listed as a persistent organic pollutant, and is frequently found in agricultural environments during monitoring processes owing to its heavy use and persistent characteristics. This study was conducted to understand the effects of endosulfan on the development of zebrafish (Danio rerio) embryos by exposing them to a specific range of endosulfan concentrations. Exposing zebrafish embryos to endosulfan for 96 h yielded no acute toxicity until the concentration reached 1500 μg L−1, whereas malformed zebrafish larvae developed severely curved spines and shortened tails. About 50% of zebrafish larvae were malformed when exposed to 600 μg L−1 of endosulfan. Comparative gene expression using real-time quantitative polymerase chain reaction was assessed using endosulfan-exposed zebrafish embryos. CYP1A and CYP3A were significantly enhanced in response to endosulfan treatment. Two genes, acacb and fasn, encoding acetyl-CoA carboxylase b and fatty acid synthase proteins, respectively, were also up-regulated after treating zebrafish embryos with endosulfan. These genes are also involved in fatty acid biosynthesis. The genes encoding vitellogenin and Hsp70 increased in a concentration-dependent manner in embryos. Finally, biochemical studies showed that acetylcholinesterase activity was reduced, whereas glutathione S-transferase and carboxylesterase activities were enhanced in zebrafish embryos after endosulfan treatment. These biochemical and molecular biological differences might be used for tools to determine contamination of endosulfan in the aquatic environment.
Highlights
IntroductionEndosulfan has been widely used as a broad-spectrum insecticide since the 1950s, especially in areas of cotton cultivation to control the cotton bollworm Helicoverpa zea or H. armigera, which are some of the most problematic insect pests in the world owing to the development of insecticide resistance.[1,2] For example, the heavy use of endosulfan for the control of the cotton bollworm has caused endosulfan resistance in this species.[3,4]endosulfan use has been reduced because of its long persistence in agricultural areas, strong toxicity to fish in aquatic ecosystems, and harmful effects to agricultural workers.[5,6,7,8,9] Its long persistence has been reported in many countries, including Korea, Japan, and China.[5,10,11,12] After being included on the list of persistent organic pollutants, it has been banned and phased out of the market in several countries, including Korea.[5]
Biochemical studies showed that acetylcholinesterase activity was reduced, whereas glutathione S-transferase and carboxylesterase activities were enhanced in zebrafish embryos after endosulfan treatment
This finding increased in a concentration-dependent manner in endosulfan-exposed zebrafish embryos (Figure 1(a) and (b))
Summary
Endosulfan has been widely used as a broad-spectrum insecticide since the 1950s, especially in areas of cotton cultivation to control the cotton bollworm Helicoverpa zea or H. armigera, which are some of the most problematic insect pests in the world owing to the development of insecticide resistance.[1,2] For example, the heavy use of endosulfan for the control of the cotton bollworm has caused endosulfan resistance in this species.[3,4]endosulfan use has been reduced because of its long persistence in agricultural areas, strong toxicity to fish in aquatic ecosystems, and harmful effects to agricultural workers.[5,6,7,8,9] Its long persistence has been reported in many countries, including Korea, Japan, and China.[5,10,11,12] After being included on the list of persistent organic pollutants, it has been banned and phased out of the market in several countries, including Korea.[5]. Except for some countries that use endosulfan for certain applications, endosulfan may be permanently banned from use.[13]
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