title: Molecular cloning and characterisation of a novel P-glycoprotein in the salmon louse Lepeophtheirus salmonis.
abstract: The salmon louse, Lepeophtheirus salmonis, is a crustacean ectoparasite of salmonid fish. At present, sea louse control on salmon farms relies heavily upon chemical treatments. Drug efflux transport, mediated by ABC transporters such as P-glycoprotein (Pgp), represents a major mechanism for drug resistance in parasites. We report here the molecular cloning of a new Pgp from the salmon louse, called SL-PGY1. A partial Pgp sequence was obtained by searching sea louse ESTs, and extended by rapid amplification of cDNA ends (RACE). The open reading frame of SL-PGY1 encodes a protein of 1438 amino acids that possesses typical structural traits of P-glycoproteins, and shows a high degree of sequence homology to invertebrate and vertebrate P-glycoproteins. In the absence of drug exposure, SL-PGY1 mRNA expression levels did not differ between a drug-susceptible strain of L. salmonis and a strain showing a ~7-fold decrease in sensitivity against emamectin benzoate, the active component of the in-feed sea louse treatment SLICE (Merck Animal Health). Aqueous exposure of the hyposensitive salmon louse strain to emamectin benzoate (24h, 410 μg/L) provoked a 2.9-fold upregulation of SL-PGY1. Adult male lice of both strains showed a greater abundance of SL-PGY1 mRNA than adult females.
authors.affiliation: Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, Scotland, United Kingdom.
authors.forename: Jan
authors.initials: J
authors.lastname: Heumann
authors.forename: Stephen
authors.initials: S
authors.lastname: Carmichael
authors.forename: James E
authors.initials: JE
authors.lastname: Bron
authors.forename: Andy
authors.initials: A
authors.lastname: Tildesley
authors.forename: Armin
authors.initials: A
authors.lastname: Sturm
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000145:classification / Q000235:genetics*; D000818:Animals; D000977:Antiparasitic Agents / Q000494:pharmacology; D003001:Cloning, Molecular; D033342:Copepoda / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D004247:DNA / Q000737:chemistry / Q000235:genetics; D005260:Female; D005393:Fish Diseases / Q000469:parasitology*; D015870:Gene Expression / Q000187:drug effects; D007559:Ivermectin / Q000031:analogs & derivatives / Q000494:pharmacology; D008297:Male; D008969:Molecular Sequence Data; D010802:Phylogeny; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012474:Salmon / Q000469:parasitology*; D017422:Sequence Analysis, DNA
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000977:Antiparasitic Agents; D007559:Ivermectin; D004247:DNA; C108024:emamectin benzoate