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To better understand chemical effects on vitellogenin gene regulation , we tested the hypothesis that activation of the aryl hydrocarbon receptor 2 ( AHR2 ) by dioxin inhibits the estrogen receptor pathway regulation of 3 vitellogenin genes ( vtg1 - 3 ) in vivo , using zebrafish ( Danio rerio ) as a model teleost .
 Chemical: aryl hydrocarbon; Chemical: dioxin; Chemical: estrogen
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: aryl hydrocarbon; Chemical: dioxin; Chemical: estrogen