Genomic analysis of the carboxylesterase family in the salmon louse (Lepeophtheirus salmonis)

TitleGenomic analysis of the carboxylesterase family in the salmon louse (Lepeophtheirus salmonis)
AuthorsTschesche C, Bekaert M, Humble JL, Bron JE, Sturm A
TypeJournal Article
Journal NameComparative biochemistry and physiology. Toxicology & pharmacology : CBP
CitationTschesche C, Bekaert M, Humble JL, Bron JE, Sturm A. Genomic analysis of the carboxylesterase family in the salmon louse (Lepeophtheirus salmonis). Comparative biochemistry and physiology. Toxicology & pharmacology : CBP. 2021 Jun 10; 248:109095.


The pyrethroid deltamethrin and the macrocyclic lactone emamectin benzoate (EMB) are used to treat infestations of farmed salmon by parasitic salmon lice, Lepeophtheirus salmonis. While the efficacy of both compounds against Atlantic populations of the parasite has decreased as a result of the evolution of resistance, the molecular mechanisms of drug resistance in L. salmonis are currently not fully understood. The functionally diverse carboxylesterases (CaE) family includes members involved in pesticide resistance phenotypes of terrestrial arthropods. The present study had the objective to characterize the CaE family in L. salmonis and assess its role in drug resistance. L. salmonis CaE homologues were identified by homology searches in the parasite's transcriptome and genome. The transcript expression of CaEs predicted to be catalytically competent was studied using quantitative reverse-transcription PCR in drug susceptible and multi-resistant L. salmonis. The above strategy led to the identification of 21 CaEs genes/pseudogenes. Phylogenetic analyses assigned 13 CaEs to clades involved in neurodevelopmental signaling and cell adhesion, while three sequences were predicted to encode secreted enzymes. Ten CaEs were identified as being potentially catalytically competent. Transcript expression of acetylcholinesterase (ace1b) was significantly increased in multi-resistant lice compared to drug-susceptible L. salmonis, with transcript abundance further increased in preadult-II females following EMB exposure. In summary, results from the present study demonstrate that L. salmonis possesses fewer CaE gene family members than most arthropods characterized so far. Drug resistance in L. salmonis was associated with overexpression of ace1b.

Author Details
Additional information about authors:
1Claudia Tschesche
2Michaël Bekaert
3Joseph L Humble
4James E Bron
5Armin Sturm
Additional details for this publication include:
Property NameValue
Publication ModelPrint-Electronic
Publication Date2021 Jun 10
Journal AbbreviationComp Biochem Physiol C Toxicol Pharmacol
CopyrightCopyright © 2021. Published by Elsevier Inc.
Language Abbreng
Publication TypeJournal Article
Journal CountryUnited States
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PMID: PMID:34098083