title: Clonorchis sinensis acetoacetyl-CoA thiolase: identification and characterization of its potential role in surviving in the bile duct.
abstract: BACKGROUND
  Clonorchis sinensis (C. sinensis) inhabits in bile duct of the host. However, the mechanisms involved in why C. sinensis can survive in the bile environment containing lipids have not yet been explored. In this study, C. sinensis acetoacetyl-CoA thiolase (CsACAT), a member of the thiolase family which has a key role in the beta oxidation pathway of fatty acid production, was identified and characterized to understand its potential role in adapting to the bile environment.
  
  
  METHODS
  The encoding sequence, conserved domains and spatial structure of CsACAT were identified and analyzed by bioinformatic tools. Recombinant CsACAT (rCsACAT) was obtained using a procaryotic expression system. The expression pattern of CsACAT was confirmed by quantitative real-time PCR, western blotting, and immunofluorescence. Gradients of lecithin were then set to culture C. sinensis adults in vitro and the survival rate of C. sinensis was analyzed, as well as the expression level and enzymatic activity of CsACAT in different lipid environments. Hypercholesteremia rabbit models were established by feeding with a hyperlipidemic diet and then infected intragastrically with C. sinensis. One and a half months later, the worm burdens and the expression level of CsACAT was detected.
  
  
  RESULTS
  CsACAT was confirmed to be a member of the thiolase family and present in the excretory/secretory proteins of C. sinensis. CsACAT was specifically localized at the vitellarium and sub-tegumental muscle layer in adult worms. The mRNA level of CsACAT in eggs was higher than those in adult worms and metacercariae. When adult worms were cultured with higher concentration of lecithin, the expression level and enzyme activity of CsACAT were up-regulated. The survival rate of adult worms was higher than control group. More adult worms were recovered from hypercholesteremia rabbit models. The expression level of CsACAT in these worms was higher than control group.
  
  
  CONCLUSIONS
  Our results implied that C. sinensis might sense lipid levels and survive better in the bile environment with higher lipid levels. C. sinensis might modulate the expression and enzymatic activity of CsACAT, an enzyme involved in fatty acid metabolism, for energy or physical requirements to adapt to the host.
authors.affiliation: Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, 74 Zhongshan 2nd Road, Guangzhou, 510080, People's Republic of China. linjinsi1989@gmail.com.|Key Laboratory for Tropical Diseases Control, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080, People's Republic of China. linjinsi1989@gmail.com.
authors.forename: Jinsi
authors.initials: J
authors.lastname: Lin
authors.affiliation: Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, 74 Zhongshan 2nd Road, Guangzhou, 510080, People's Republic of China. 331024005@qq.com.|Key Laboratory for Tropical Diseases Control, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080, People's Republic of China. 331024005@qq.com.
authors.forename: Hongling
authors.initials: H
authors.lastname: Qu
authors.affiliation: Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, 74 Zhongshan 2nd Road, Guangzhou, 510080, People's Republic of China. chgshan@yahoo.cn.
authors.forename: Guishan
authors.initials: G
authors.lastname: Chen
authors.affiliation: Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, 74 Zhongshan 2nd Road, Guangzhou, 510080, People's Republic of China. 972976636@qq.com.|Key Laboratory for Tropical Diseases Control, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080, People's Republic of China. 972976636@qq.com.
authors.forename: Lei
authors.initials: L
authors.lastname: He
authors.affiliation: Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, 74 Zhongshan 2nd Road, Guangzhou, 510080, People's Republic of China. 252734100@qq.com.|Key Laboratory for Tropical Diseases Control, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080, People's Republic of China. 252734100@qq.com.
authors.forename: Yanquan
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, 74 Zhongshan 2nd Road, Guangzhou, 510080, People's Republic of China. 812583630@qq.com.|Key Laboratory for Tropical Diseases Control, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080, People's Republic of China. 812583630@qq.com.
authors.forename: Zhizhi
authors.initials: Z
authors.lastname: Xie
authors.affiliation: Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, 74 Zhongshan 2nd Road, Guangzhou, 510080, People's Republic of China. 519616579@qq.com.|Key Laboratory for Tropical Diseases Control, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080, People's Republic of China. 519616579@qq.com.
authors.forename: Mengyu
authors.initials: M
authors.lastname: Ren
authors.affiliation: Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, 74 Zhongshan 2nd Road, Guangzhou, 510080, People's Republic of China. sunjiuf@163.com.|Key Laboratory for Tropical Diseases Control, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080, People's Republic of China. sunjiuf@163.com.
authors.forename: Jiufeng
authors.initials: J
authors.lastname: Sun
authors.affiliation: Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, 74 Zhongshan 2nd Road, Guangzhou, 510080, People's Republic of China. 185777388@qq.com.|Key Laboratory for Tropical Diseases Control, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080, People's Republic of China. 185777388@qq.com.
authors.forename: Shan
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, 74 Zhongshan 2nd Road, Guangzhou, 510080, People's Republic of China. 179307641@qq.com.|Key Laboratory for Tropical Diseases Control, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080, People's Republic of China. 179307641@qq.com.
authors.forename: Wenjun
authors.initials: W
authors.lastname: Chen
authors.affiliation: Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, 74 Zhongshan 2nd Road, Guangzhou, 510080, People's Republic of China. 741081181@qq.com.|Key Laboratory for Tropical Diseases Control, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080, People's Republic of China. 741081181@qq.com.
authors.forename: Xueqing
authors.initials: X
authors.lastname: Chen
authors.affiliation: Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, 74 Zhongshan 2nd Road, Guangzhou, 510080, People's Republic of China. wangxysean@gmail.com.|Key Laboratory for Tropical Diseases Control, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080, People's Republic of China. wangxysean@gmail.com.
authors.forename: Xiaoyun
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, 74 Zhongshan 2nd Road, Guangzhou, 510080, People's Republic of China. xuerong2@mail.sysu.edu.cn.|Key Laboratory for Tropical Diseases Control, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080, People's Republic of China. xuerong2@mail.sysu.edu.cn.
authors.forename: Xuerong
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, 74 Zhongshan 2nd Road, Guangzhou, 510080, People's Republic of China. liangchi@mail.sysu.edu.cn.|Key Laboratory for Tropical Diseases Control, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080, People's Republic of China. liangchi@mail.sysu.edu.cn.
authors.forename: Chi
authors.initials: C
authors.lastname: Liang
authors.affiliation: Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, 74 Zhongshan 2nd Road, Guangzhou, 510080, People's Republic of China. huang66@mail.sysu.edu.cn.|Key Laboratory for Tropical Diseases Control, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080, People's Republic of China. huang66@mail.sysu.edu.cn.
authors.forename: Yan
authors.initials: Y
authors.lastname: Huang
authors.affiliation: Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, 74 Zhongshan 2nd Road, Guangzhou, 510080, People's Republic of China. yuhxteam@163.com.|Key Laboratory for Tropical Diseases Control, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080, People's Republic of China. yuhxteam@163.com.
authors.forename: Xinbing
authors.initials: X
authors.lastname: Yu
mesh_terms: D000101:Acetyl-CoA C-Acetyltransferase / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001652:Bile Ducts / Q000378:metabolism*; D003001:Cloning, Molecular; D003003:Clonorchiasis / Q000469:parasitology*; D003004:Clonorchis sinensis / Q000201:enzymology* / Q000235:genetics; D015801:Helminth Proteins / Q000235:genetics; D008055:Lipids; D058488:Metacercariae; D008969:Molecular Sequence Data; D011817:Rabbits; D017423:Sequence Analysis, RNA
chemical_list: D015801:Helminth Proteins; D008055:Lipids; D000101:Acetyl-CoA C-Acetyltransferase