title: Salmon olfaction is impaired by an environmentally realistic pesticide mixture.
abstract: Many of the salmon-producing waterways of the world contain pesticides known to harm olfactory sensory neurons (OSNs) that are critically important throughout the salmon lifecycle. The ability of OSNs to retain functionality after exposure to complex pesticide mixtures remains unknown. Here we show that a 96-h exposure to an environmentally realistic concentration of a mixture made from the ten most frequently occurring pesticides in British Columbia's Nicomekl River reduced the OSN responses of rainbow troutto a behaviorally relevant odorant. Odor-evoked responses were not altered by exposure to one-fifth of the realistic concentration, and this may have been due an upregulation in detoxification enzymes, since glutathione-S-transferase activity reached a maximum (> 32% above control) at this concentration. Mixture exposure did not help to prevent OSN impairment from a second, brief (5 min) exposure to a higher (20 x) concentration of the mixture, suggesting longer-term, low-concentration exposures may not prevent damage from brief, high-concentration pulse exposures. This study demonstrates that environmentally observed pesticide mixtures can injure salmon olfactory tissue, and by extension, contribute to the threatened and endangered status of many salmon stocks.
authors.affiliation: Department of Biological Sciences, Simon Fraser University, Burnaby BC V5A 1S6, Canada.
authors.forename: Keith B
authors.initials: KB
authors.lastname: Tierney
authors.forename: Jessica L
authors.initials: JL
authors.lastname: Sampson
authors.forename: Peter S
authors.initials: PS
authors.lastname: Ross
authors.forename: Mark A
authors.initials: MA
authors.lastname: Sekela
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Kennedy
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001955:British Columbia; D008401:Gas Chromatography-Mass Spectrometry; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D005982:Glutathione Transferase / Q000378:metabolism; D009475:Neurons, Afferent / Q000187:drug effects; D017686:Oncorhynchus mykiss / Q000502:physiology*; D010575:Pesticides / Q000633:toxicity*; D045483:Rivers / Q000737:chemistry*; D012903:Smell / Q000187:drug effects* / Q000502:physiology; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D010575:Pesticides; D014874:Water Pollutants, Chemical; D005982:Glutathione Transferase