title: Novel point mutation in the sodium channel gene of pyrethroid-resistant sea lice Lepeophtheirus salmonis (Crustacea: Copepoda).
abstract: Knockdown resistance (kdr) to pyrethroid insecticides is caused by point mutations in the pyrethroid target site, the para-type sodium channel of nerve membranes. This most commonly involves alterations within the domain II (S4-S6) region of the channel protein, where several different mutation sites have been identified across a range of insect species. To investigate the possibility that a kdr-type mechanism is responsible for pyrethroid resistance in sea lice, a domain II region of the Lepeophtheirus salmonis sodium channel gene was PCR amplified and sequenced. To our knowledge, this is the first published sodium channel sequence from a crustacean. Comparison of sequences from a range of samples, including several individuals from areas in which control failures had been reported, failed to identify any of the mutations within this region that have previously been linked with resistance. Instead, a novel glutamine to arginine mutation, Q945R, in transmembrane segment IIS5 was consistently found in the samples from areas of control failure and may therefore be associated with resistance to pyrethroids in this species.
authors.affiliation: Norwegian School of Veterinary Science, PO Box 8146 Dep, 0033 Oslo, Norway. anders.fallang@veths.no
authors.forename: Anders
authors.initials: A
authors.lastname: Fallang
authors.forename: Ian
authors.initials: I
authors.lastname: Denholm
authors.forename: Tor Einar
authors.initials: TE
authors.lastname: Horsberg
authors.forename: Martin S
authors.initials: MS
authors.lastname: Williamson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016000:Cluster Analysis; D033342:Copepoda / Q000235:genetics*; D017931:DNA Primers; D040461:Gene Components; D007305:Insecticide Resistance / Q000235:genetics*; D008969:Molecular Sequence Data; D009664:Norway; D010802:Phylogeny; D017354:Point Mutation / Q000235:genetics*; D017434:Protein Structure, Tertiary; D011722:Pyrethrins; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D015222:Sodium Channels / Q000235:genetics*
chemical_list: D017931:DNA Primers; D011722:Pyrethrins; D015222:Sodium Channels