E-MTAB-1484 - Profiling constitutive gene expression in two Lepeophtheirus salmonis populations with differing susceptibilities to emamectin benzoate
Released on 6 November 2013, last updated on 3 May 2014
Caligid copepods, also called sea lice, are common ectoparasites of wild and farmed marine fish. The salmon louse Lepeophtheirus salmonis (Krøyer, 1837) has emerged as a serious problem for salmon farming in the Northern hemisphere. The annual cost of sea lice to the global salmon mariculture industry has been estimated at €300 million, of which the majority accounts for the cost of chemically treating the farmed salmon. The treatments available for salmonids with sea lice infestation have been limited with a large scale reliance on single products and the use of antiparasitics with similar modes of action, which when used over a long period of time can enhance the selection pressure for reduced sensitivity. Two L. salmonis laboratory strains, established from field isolates and differing in susceptibility to emamectin benzoate (EMB) were studied using a custom sea louse 15K oligonucleotide microarray and RT-qPCR. The aim of the present study was to identify differential expression of transcripts between these two strains to identify potential constitutive gene expression changes associated with reduced susceptibility to EMB. Adult male salmon lice were sampled without exposure to antiparasitic agents for the purpose of studying gene expression from unchallenged individuals. In this study changes in expression of Glutamate-gated Chloride channel (GluCl) subunits, considered the major target site for avermectin (AVM) drugs in invertebrates, was not observed, but expression changes were seen for alternative ligand-gated ion channel (LGIC) subunits that form an ion channels shown to interact with AVMs in vertebrates, but which is not traditionally considered to be a target site for AVMs in invertebrates. We hypothesise that these LGIC subunits represent additional EMB target sites in salmon lice, and that the down-regulation of these channel subunits in this EMB-resistant strain is related to the resistance phenotype.
transcription profiling by array, reference, strain or line
Salmon lice (Lepeophtheirus salmonis) showing varying emamectin benzoate susceptibilities differ in neuronal acetylcholine receptor and GABA-gated chloride channel mRNA expression. Carmichael, S.N., Bron, J.E., Taggart, J.B., Ireland, J.H., Bekaert, M., Burgess, S.T.G., Skuce, P.J., Nisbet, A.J., Gharbi, K., Sturm, A. BMC Genomics 14(1):408 (2013), Europe PMC 23773482