title: Structural and functional characterization of a novel gene, Hc-daf-22, from the strongylid nematode Haemonchus contortus.
abstract: The strongylid nematode Haemonchus contortus is a parasite of major concern for modern livestock husbandry because hostile environmental conditions may induce diapause in the early fourth-stage larvae.
  
  
  
  A new gene Hc-daf-22 was identified which is the homologue of Ce-daf-22 and human SCPx. Genome walking and RACE were performed to obtain the whole cDNA and genomic sequence of this gene. Using qRT-PCR with all developmental stages as templates to explore the transcription level and micro-injection was applied to confirm the promoter activity of the 5'-flanking region. Overexpression, rescue and RNA interference experiments were performed in N2, daf-22 mutant (ok 693) strains of C. elegans to study the gene function of Hc-daf-22.
  
  
  
  The full length gene of Hc-daf-22 (6,939 bp) contained 16 exons separated by 15 introns, and encoded a cDNA of 1,602 bp (533 amino acids, estimated at about 59.3 kDa) with a peak in L3 and L4 in transcriptional level. The Hc-DAF-22 protein was consisted of a 3-oxoacyl-CoA thiolase domain and a SCP2 domain and evolutionarily conserved. The 1,548 bp fragment upstream of the 5'-flanking region was confirmed to have promoter activity compared with 5'-flanking region of Ce-daf-22. The rescue experiment by micro-injection of daf-22 (ok693) mutant strain showed significant increase in body size and brood size in the rescued worms with significantly reduced or completely absent fat granules confirmed by Oil red O staining, indicating that Hc-daf-22 could partially rescue the function of Ce-daf-22. Furthermore, RNAi with Hc-daf-22 could partially silence the endogenous Ce-daf-22 in N2 worms and mimic the phenotype of daf-22 (ok693) mutants.
  
  
  
  The gene Hc-daf-22 was isolated and its function identified using C. elegans as a model organism. Our results indicate that Hc-daf-22 shared similar characteristics and function with Ce-daf-22 and may play an important role in peroxisomal β-oxidation and the development in H. contortus.
authors.affiliation: College of Animal Sciences, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Zhejiang University, Hangzhou, 310058, China.
authors.forename: Xiaolu
authors.initials: X
authors.lastname: Guo
authors.affiliation: Zhejiang Center of Animal Disease Control, Hangzhou, 310020, China.
authors.forename: Hongli
authors.initials: H
authors.lastname: Zhang
authors.affiliation: College of Animal Sciences, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Zhejiang University, Hangzhou, 310058, China.
authors.forename: Xiuping
authors.initials: X
authors.lastname: Zheng
authors.affiliation: Faculty of Life Science and Biotechnology, Ningbo University, Ningbo, 315211, China.
authors.forename: Qianjin
authors.initials: Q
authors.lastname: Zhou
authors.affiliation: College of Animal Sciences, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Zhejiang University, Hangzhou, 310058, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Yang
authors.affiliation: College of Animal Sciences, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Zhejiang University, Hangzhou, 310058, China.
authors.forename: Xueqiu
authors.initials: X
authors.lastname: Chen
authors.affiliation: College of Animal Sciences, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Zhejiang University, Hangzhou, 310058, China. afdu@zju.edu.cn.|Present address: Institute of Preventive Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China. afdu@zju.edu.cn.
authors.forename: Aifang
authors.initials: A
authors.lastname: Du
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans / Q000469:parasitology; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism; D006188:Haemonchiasis / Q000469:parasitology / Q000662:veterinary*; D006189:Haemonchus / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015801:Helminth Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D012756:Sheep; D012757:Sheep Diseases / Q000469:parasitology*
chemical_list: D018076:DNA, Complementary; D015801:Helminth Proteins
keywords: Caenorhabditis elegans; Diapause; Haemonchus contortus; Hc-daf-22; β-oxidation