E-MTAB-1478 - Profiling gene expression in two Lepeophtheirus salmonis populations with differing susceptibilities to emamectin benzoate upon in vitro exposure to sublethal concentrations of this antiparasitic compound.
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. The aim of the present study was to identify transcripts whose expression correlated to emamectin benzoate (EMB) susceptibility, or those genes regulated in response to EMB exposure. Two L. salmonis laboratory strains, established from field isolates and differing in susceptibility to EMB were studied using a custom sea louse 15K oligonucleotide microarray and RT-qPCR. Adult male sea lice were sampled from both strains after 1 and 3 hours of aqueous exposure to 0.2 µg mL-1 emamectin benzoate, 0.01% PEG300 or sea water. Bioinformatic analysis identified that in the absence of drug treatment, a large number of genes were significantly down regulated in the louse strain hyposensitive to EMB. EMB exposure had marked effects on gene expression in the EMB susceptible strain, but caused little changes in EMB hyposensitive lice. We therefore suggest that transcriptional responses induced by EMB exposure may not be responsible for reduced susceptibility to this antiparasitic compound, but may involve genes that are constitutively expressed in EMB tolerant salmon louse strains.
transcription profiling by array, in vitro, 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