Dataset Information

A pedigree-based experiment reveals variation in salinity and thermal tolerance in the salmon louse, Lepeophtheirus salmonis.

ABSTRACT: The salmon louse is a highly abundant ectoparasitic copepod of salmonids in the North Pacific and Atlantic. Widespread and rapid development of resistance to chemical agents used to delouse salmonids on marine farms is now threatening the continued development of the aquaculture industry and have served as a potent catalyst for the development of alternative pest management strategies. These include freshwater and warm-water treatments to which the louse is sensitive. However, given the well-documented evolutionary capacity of this species, the risk of developing tolerance towards these environmental treatments cannot be dismissed. Two common-garden experiments were performed using full-sibling families of lice identified by DNA parentage testing to investigate whether one of the fundamental premises for evolution, in this context genetic variation in the capacity of coping with fresh or warm water, exists within this species. Significant differences in survival were observed among families in both experiments, although for the salinity experiment, it was not possible to unequivocally disentangle background mortality from treatment-induced mortality. Thus, our data demonstrate genetic variation in tolerance of warm water and are suggestive of genetic variation in salinity tolerance. We conclude that extensive use of these environmental-based treatments to delouse salmonids on commercial farms may drive lice towards increased tolerance.

SUBMITTER: Ljungfeldt LER

PROVIDER: S-EPMC5680634 | biostudies-literature | 2017 Dec

REPOSITORIES: biostudies-literature

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A pedigree-based experiment reveals variation in salinity and thermal tolerance in the salmon louse, <i>Lepeophtheirus salmonis</i>.

Ljungfeldt Lina Eva Robin LER Quintela María M Besnier François F Nilsen Frank F Glover Kevin Alan KA

Evolutionary applications 20170816 10

The salmon louse is a highly abundant ectoparasitic copepod of salmonids in the North Pacific and Atlantic. Widespread and rapid development of resistance to chemical agents used to delouse salmonids on marine farms is now threatening the continued development of the aquaculture industry and have served as a potent catalyst for the development of alternative pest management strategies. These include freshwater and warm-water treatments to which the louse is sensitive. However, given the well-doc ...[more]

PMID: 29151856

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Project description:BackgroundHydrogen peroxide (H2O2) is one of the delousing agents used to control sea lice infestations in salmonid aquaculture. However, some Lepeophtheirus salmonis populations have developed resistance towards H2O2. An increased gene expression and activity of catalase, an enzyme that breaks down H2O2, have been detected in resistant lice, being therefore introduced as a resistance marker in the salmon industry. In the present study the aim was to validate the use of catalase expression as a marker and to identify new candidate genes as additional markers to catalase, related to H2O2 resistance in L. salmonis.MethodsA sensitive and an H2O2 resistant laboratory strain (P0 generation, not exposed to H2O2 for several years) were batch crossed to generate a cohort with a wide range of H2O2 sensitivities (F2 generation). F2 adult females were then exposed to H2O2 to separate sensitive and resistant individuals. Those F2 lice, the P0 lice and field-collected resistant lice (exposed to H2O2 in the field) were used in an RNA sequencing study.ResultsCatalase was upregulated in resistant lice exposed to H2O2 compared to sensitive lice. This was, however, not the case for unexposed resistant P0 lice. Several other genes were found differentially expressed between sensitive and resistant lice, but most of them seemed to be related to H2O2 exposure. However, five genes were consistently up- or downregulated in the resistant lice independent of exposure history. The upregulated genes were: one gene in the DNA polymerase family, one gene encoding a Nesprin-like protein and an unannotated gene encoding a small protein. The downregulated genes encoded endoplasmic reticulum resident protein 29 and an aquaporin (Glp1_v2).ConclusionsCatalase expression seems to be induced by H2O2 exposure, since it was not upregulated in unexposed resistant lice. This may pose a challenge for its use as a resistance marker. The five new genes associated with resistance are put forward as complementary candidate genes. The most promising was Glp1_v2, an aquaglyceroporin that may serve as a passing channel for H2O2. Lower channel number can reduce the influx or distribution of H2O2 in the salmon louse, being directly involved in the resistance mechanism.

Dataset Information

A pedigree-based experiment reveals variation in salinity and thermal tolerance in the salmon louse, Lepeophtheirus salmonis.

Publications

A pedigree-based experiment reveals variation in salinity and thermal tolerance in the salmon louse, <i>Lepeophtheirus salmonis</i>.

Similar Datasets

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