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dc.contributor.authorHeumann, Janen_UK
dc.contributor.authorCarmichael, Stephen Nen_UK
dc.contributor.authorBron, Jamesen_UK
dc.contributor.authorSturm, Arminen_UK
dc.description.abstractThe salmon louse Lepeophtheirus salmonis (Krøyer, 1837) is an ectoparasite of salmonid fish severely affecting cultured salmon production in the North Atlantic. Salmon louse control on farms currently relies in part upon the use of veterinary drugs; however, as only a limited number of salmon delousing agents are available, there are concerns about development of drug resistance in salmon lice. The common anti-salmon louse drug SLICE® (Merck Animal Health) contains the avermectin emamectin benzoate (EMB). Members of the large gene superfamily of ABC (ATP-binding cassette) transporters have been identified as potential avermectin resistance factors in parasitic nematodes. In salmon lice, only three ABC transporters have been cloned and studied to date. We report here upon the isolation of four novel L. salmonis ABC transporters, and employ an inhibitor-based approach to assess roles of L. salmonis ABC transporters in the toxicology of EMB. To isolate salmon louse ABC transporters, publicly available L. salmonis expressed sequence tags (ESTs) were subjected to homology searches, and the retrieved ESTs assembled into contiguous sequences and annotated. Potential ABC drug transporters isolated by this approach included four multidrug resistance-associated proteins (MRPs). In addition, five ABC proteins likely having roles unrelated to drug resistance were obtained. Quantitative real time PCR (RT-qPCR) was used to analyse mRNA levels of the MRPs in L. salmonis strains differing in EMB susceptibility. In the absence of EMB, all studied MRPs showed similar transcript levels in the drug-susceptible strain S and the moderately EMB-resistant strain R. Moreover, mRNA expression of the four studied MRPs remained unaffected by exposure to EMB. Taken together, the results of RT-qPCR analyses did not provide evidence for roles of the studied MRPs as factors affecting EMB susceptibility. Further experiments used an inhibitor-based approach to investigate the roles of ABC transporters in EMB toxicity. In immotility bioassays, salmon lice of the two strains were exposed to EMB, provided alone or in combination with cyclosporin A or verapamil, which are known inhibitors of P-glycoprotein and MRPs. Cyclosporin A increased EMB toxicity to a similar degree with both strains, suggesting the biochemical factors affected by this inhibitor show similar levels in both strains. In contrast, verapamil increased EMB effects only in the R strain. This result could be indicative of an enhanced expression of hitherto unknown ABC transporters in the moderately EMB-resistant R strain. More research is required to identify the target of verapamil in salmon lice.en_UK
dc.relationHeumann J, Carmichael SN, Bron J & Sturm A (2014) Isolation and characterisation of four partial cDNA sequences encoding multidrug resistance-associated proteins (MRPs) in the salmon louse Lepeophtheirus salmonis (Krøyer, 1837). Aquaculture, 424-425, pp. 207-214.
dc.rightsThe publisher does not allow this work to be made publicly available in this Repository. Please use the Request a Copy feature at the foot of the Repository record to request a copy directly from the author. You can only request a copy if you wish to use this work for your own research or private study.en_UK
dc.subjectABC transporteren_UK
dc.subjectDrug resistanceen_UK
dc.subjectEmamectin benzoateen_UK
dc.subjectSea liceen_UK
dc.titleIsolation and characterisation of four partial cDNA sequences encoding multidrug resistance-associated proteins (MRPs) in the salmon louse Lepeophtheirus salmonis (Krøyer, 1837)en_UK
dc.typeJournal Articleen_UK
dc.rights.embargoreason[Heumann2014.pdf] The publisher does not allow this work to be made publicly available in this Repository therefore there is an embargo on the full text of the work.en_UK
dc.type.statusVoR - Version of Recorden_UK
dc.contributor.affiliationUniversity of Stirlingen_UK
dc.contributor.affiliationUniversity of Stirlingen_UK
dc.contributor.affiliationInstitute of Aquacultureen_UK
dc.contributor.affiliationInstitute of Aquacultureen_UK
rioxxterms.apcnot requireden_UK
rioxxterms.typeJournal Article/Reviewen_UK
local.rioxx.authorHeumann, Jan|en_UK
local.rioxx.authorCarmichael, Stephen N|en_UK
local.rioxx.authorBron, James|0000-0003-3544-0519en_UK
local.rioxx.authorSturm, Armin|0000-0003-2632-1999en_UK
local.rioxx.projectInternal Project|University of Stirling|
Appears in Collections:Aquaculture Journal Articles

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