title: Swim bladder nematodes (Anguillicoloides crassus) disturb silvering in European eels (Anguilla anguilla).
abstract: The introduced parasite Anguillicoloides crassus is thought to play an important role in the decline of freshwater eel (Anguilla spp.) populations. These nematodes are known to negatively affect many fitness-related traits in eels. We used experimental infections to study the effect of A. crassus on the relative size or mass of organs, and the expression of functionally relevant genes (total of 12 parameters) that are involved in the silvering process of Anguilla anguilla. Our results showed that the liver mass, the hemoglobin α-chain, and androgen receptors α expression levels were significantly higher in infected eels, whereas the freshwater rod opsin expression level and the gut mass were significantly lower in infected eels. Our results suggested that infected eels were at a more advanced stage in the silvering process than uninfected counterparts of similar size. These results may be explained by 2 hypotheses. First, A. crassus could trigger physiological mechanisms involved in the silvering process as a side-effect of infection. Second, eels may adjust their life history traits in response to infection. The implications for eel migration and reproductive success may be either negative or positive, depending on whether the response to A. crassus infection results in an additional cost of the parasite or is due to the phenotypic plasticity of the host.
authors.affiliation: CNRS-EPHE, USR 3278, CRIOBE, BP 1013, Papetoai, Moorea, Polynésie Française.
authors.forename: Géraldine
authors.initials: G
authors.lastname: Fazio
authors.forename: Pierre
authors.initials: P
authors.lastname: Sasal
authors.forename: Gabriel
authors.initials: G
authors.lastname: Mouahid
authors.forename: Raymonde
authors.initials: R
authors.lastname: Lecomte-Finiger
authors.forename: Hélène
authors.initials: H
authors.lastname: Moné
mesh_terms: D000222:Adaptation, Physiological; D000400:Air Sacs / Q000469:parasitology*; D000811:Anguilla / Q000254:growth & development / Q000469:parasitology* / Q000502:physiology*; D058500:Animal Fins / Q000254:growth & development / Q000502:physiology; D025041:Animal Migration / Q000502:physiology; D000818:Animals; D017176:Dracunculoidea / Q000502:physiology*; D005123:Eye / Q000033:anatomy & histology; D005393:Fish Diseases / Q000469:parasitology / Q000473:pathology / Q000503:physiopathology*; D041981:Gastrointestinal Tract / Q000187:drug effects / Q000254:growth & development; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D055554:Hemoglobin Subunits / Q000235:genetics / Q000378:metabolism; D008099:Liver / Q000254:growth & development; D008297:Male; D009799:Ocular Physiological Phenomena; D055355:Opsins / Q000235:genetics / Q000378:metabolism; D011944:Receptors, Androgen / Q000235:genetics / Q000378:metabolism; D012098:Reproduction / Q000502:physiology; D012880:Skin Pigmentation / Q000502:physiology; D028021:Sodium-Potassium-Chloride Symporters / Q000235:genetics / Q000378:metabolism; D017205:Spirurida Infections / Q000473:pathology / Q000503:physiopathology / Q000662:veterinary*; D013739:Testosterone / Q000031:analogs & derivatives / Q000494:pharmacology; D014882:Water-Electrolyte Balance / Q000502:physiology
chemical_list: D055554:Hemoglobin Subunits; D055355:Opsins; D011944:Receptors, Androgen; D028021:Sodium-Potassium-Chloride Symporters; D013739:Testosterone; C003600:11-ketotestosterone