title: Molecular characterization of a defensin gene from a hard tick, Dermacentor silvarum.
abstract: BACKGROUND
  Ticks are distributed worldwide and considered as vectors of many human diseases. Tick defensins, a family of antimicrobial peptides, form the first line of defense against pathogens.
  
  
  RESULTS
  A defensin-like gene, named Ds-defensin, was identified from a cDNA library of the hard tick Dermacentor silvarum collected from northeast China. The full-length cDNA of Ds-defensin was 225 bp, encoding a 74 amino acid peptide. The nucleotide sequence of Ds-defensin shared 98.2% similarity to putative defensin from Dermacentor marginatus. RT-PCR results suggested that Ds-defensin was extensively expressed in tick salivary gland and midgut, with a higher expression level in midgut. Ds-defensin showed broad antimicrobial activity against various Gram-positive and Gram-negative bacteria, as well as the fungus Candida albicans.
  
  
  CONCLUSIONS
  We characterized a functional defensin from D. silvarum of China. Ds-defensin showed bactericidal activity against various Gram-positive and Gram-negative bacteria. Ds-defensin can be expected to be introduced to the medical field as a new molecule with antibacterial activity.
authors.forename: Juanjuan
authors.initials: J
authors.lastname: Wang
authors.forename: Gang
authors.initials: G
authors.lastname: Bian
authors.forename: Wen
authors.initials: W
authors.lastname: Pan
authors.affiliation: Institute of Biology and Medical Sciences, Jiangsu Key Laboratory of Infection and Immunity, Soochow University, Suzhou City, Jiangsu Province, People's Republic of China. ttfeng@suda.edu.cn.
authors.forename: Tingting
authors.initials: T
authors.lastname: Feng
authors.forename: Jianfeng
authors.initials: J
authors.lastname: Dai
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000890:Anti-Infective Agents / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D001096:Arachnid Vectors / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D002176:Candida albicans / Q000187:drug effects*; D023082:Defensins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D003870:Dermacentor / Q000235:genetics* / Q000378:metabolism; D015723:Gene Library; D006090:Gram-Negative Bacteria / Q000187:drug effects*; D006094:Gram-Positive Bacteria / Q000187:drug effects*; D008969:Molecular Sequence Data; D010802:Phylogeny; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
chemical_list: D000890:Anti-Infective Agents; D023082:Defensins