title: Complete feminization of catfish by feeding Limnodilus, an annelid worm collected in contaminated streams.
abstract: BACKGROUND
  Feminization of animals derived from areas polluted by endocrine disrupting chemicals (EDCs) has been observed in all classes of vertebrates. However, feminization of artificially reared offspring by feeding of specific living organisms has never been reported.
  
  
  METHODS
  Different food (including Limnodilus spp collected from the wild) and time treatment were applied to southern catfish. In addition, EDCs in Limnodilus spp., an annelid worm collected from wild contaminated small streams, was detected by LC-MS (Liquid chromatography-mass spectrometry). Serum estradiol-17β and vitellogenin (VTG) levels and gonadal Sf1, Dmrt1, Foxl2, Cyp19a1a expression levels in the catfish were measured through Estradiol/VTG EIA Kit and real-time PCR.
  
  
  RESULTS
  Here we report that feeding of Limnodilus spp. resulted in complete feminization of southern catfish, which has a 1:1 sex ratio in wild conditions. Furthermore, HPLC analysis showed that the extraction of Limnodilus spp. contained EDCs, including bisphenol A (BPA), diethylstilbestrol (DES), 4-tert-octylphenol (4-t-OP) and 4-nonylphenol (4-NP), which were further confirmed by LC-MS. Feeding southern catfish using commercial diets sprayed with EDCs cocktail also resulted in 100% female, whereas the control fish displayed approximate 1:1 sex ratio. Limnodilus spp. fed fish displayed similar serum estradiol-17β and VTG levels and gonadal Sf1, Dmrt1, Foxl2, Cyp19a1a expression levels to those of female control.
  
  
  CONCLUSIONS
  These results demonstrated that EDCs in Limnodilus spp. cause southern catfish feminization by affecting aromatase expression and endogenous estrogen level. This is the first report showing that feeding of any living organism resulted in complete feminization of a vertebrate.
authors: Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, School of Life Science, Southwest University, Chongqing, China.
authors: Ran-ran
authors: RR
authors: Dong
authors: Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, School of Life Science, Southwest University, Chongqing, China; Department of Hematology, Xinqiao Hospital, The Third Military Medical University, Xinqiao Street, Chongqing, China.
authors: Shi-jie
authors: SJ
authors: Yang
authors: Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, School of Life Science, Southwest University, Chongqing, China.
authors: Rui-juan
authors: RJ
authors: Feng
authors: Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, School of Life Science, Southwest University, Chongqing, China.
authors: Ling-ling
authors: LL
authors: Fang
authors: Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, School of Life Science, Southwest University, Chongqing, China.
authors: Yun-lv
authors: YL
authors: Sun
authors: Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, School of Life Science, Southwest University, Chongqing, China.
authors: Yao-guang
authors: YG
authors: Zhang
authors: Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, School of Life Science, Southwest University, Chongqing, China.
authors: Xiao-jun
authors: XJ
authors: Xie
authors: Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, School of Life Science, Southwest University, Chongqing, China. Electronic address: wdeshou@swu.edu.cn.
authors: De-shou
authors: DS
authors: Wang
mesh_terms: D000818:Animals; D000845:Annelida / Q000737:chemistry*; D002397:Catfishes; D002853:Chromatography, Liquid; D052244:Endocrine Disruptors / Q000009:adverse effects / Q000032:analysis*; D005260:Female; D005262:Feminization / Q000139:chemically induced*; D006066:Gonads / Q000378:metabolism / Q000473:pathology; D008297:Male; D013058:Mass Spectrometry; D012733:Sex Differentiation; D014819:Vitellogenins / Q000097:blood; D014877:Water Pollution, Chemical / Q000009:adverse effects*
chemical_list: D052244:Endocrine Disruptors; D014819:Vitellogenins
keywords: Cyp19a1a and estrogen level; EDCs; Feminization; LC–MS; Limnodilus spp.; Southern catfish