Please use this identifier to cite or link to this item:
Appears in Collections:Aquaculture Journal Articles
Peer Review Status: Refereed
Title: Genome-wide survey of cytochrome P450 genes in the salmon louse Lepeophtheirus salmonis (Krøyer, 1837)
Author(s): Humble, Joseph L
Carmona-Antoñanzas, Greta
McNair, Carol M
Nelson, David R
Bassett, David I
Egholm, Ingibjørg
Bron, James E
Bekaert, Michaël
Sturm, Armin
Keywords: Drug resistance
Salmon farming
Lepeophtheirus salmonis
Cytochrome P450
Issue Date: Dec-2019
Citation: Humble JL, Carmona-Antoñanzas G, McNair CM, Nelson DR, Bassett DI, Egholm I, Bron JE, Bekaert M & Sturm A (2019) Genome-wide survey of cytochrome P450 genes in the salmon louse Lepeophtheirus salmonis (Krøyer, 1837). Parasites and Vectors, 12 (1), Art. No.: 563.
Abstract: Background The salmon louse (Lepeophtheirus salmonis) infests farmed and wild salmonid fishes, causing considerable economic damage to the salmon farming industry. Infestations of farmed salmon are controlled using a combination of non-medicinal approaches and veterinary drug treatments. While L. salmonis has developed resistance to most available salmon delousing agents, relatively little is known about the molecular mechanisms involved. Members of the cytochrome P450 (CYP) superfamily are typically monooxygenases, some of which are involved in the biosynthesis and metabolism of endogenous compounds, while others have central roles in the detoxification of xenobiotics. In terrestrial arthropods, insecticide resistance can be based on the enhanced expression of CYPs. The reported research aimed to characterise the CYP superfamily in L. salmonis and assess its potential roles in drug resistance. Methods Lepeophtheirus salmonis CYPs were identified by homology searches of the genome and transcriptome of the parasite. CYP transcript abundance in drug susceptible and multi-resistant L. salmonis was assessed by quantitative reverse transcription PCR, taking into account both constitutive expression and expression in parasites exposed to sublethal levels of salmon delousing agents, ecdysteroids and environmental chemicals. Results The above strategy led to the identification of 25 CYP genes/pseudogenes in L. salmonis, making its CYP superfamily the most compact characterised for any arthropod to date. Lepeophtheirus salmonis possesses homologues of a number of arthropod CYP genes with roles in ecdysteroid metabolism, such as the fruit fly genes disembodied, shadow, shade, spook and Cyp18a1. CYP transcript expression did not differ between one drug susceptible and one multi-resistant strain of L. salmonis. Exposure of L. salmonis to emamectin benzoate or deltamethrin caused the transcriptional upregulation of certain CYPs. In contrast, neither ecdysteroid nor benzo[a]pyrene exposure affected CYP transcription significantly. Conclusions The parasite L. salmonis is demonstrated to possess the most compact CYP superfamily characterised for any arthropod to date. The complement of CYP genes in L. salmonis includes conserved CYP genes involved in ecdysteroid biosynthesis and metabolism, as well as drug-inducible CYP genes. The present study does not provide evidence for a role of CYP genes in the decreased susceptibility of the multiresistant parasite strain studied.
DOI Link: 10.1186/s13071-019-3808-x
Rights: This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated.
Licence URL(s):

Files in This Item:
File Description SizeFormat 
s13071-019-3808-x.pdfFulltext - Published Version3.98 MBAdobe PDFView/Open

This item is protected by original copyright

A file in this item is licensed under a Creative Commons License Creative Commons

Items in the Repository are protected by copyright, with all rights reserved, unless otherwise indicated.

If you believe that any material held in STORRE infringes copyright, please contact providing details and we will remove the Work from public display in STORRE and investigate your claim.