title: Impact of environmental DDT concentrations on gill adaptation to increased salinity in the tilapia Sarotherodon melanotheron.
abstract: Estuaries of tropical developing countries suffering from severe droughts induced by climate change are habitats to fish, which face drastic salinity variations and the contact with pollutants. The Western Africa tilapia Sarotherodon melanotheron is highly resistant to hypersalinity, but the effect of human-released xenobiotics on its adaptation is barely known. Controlled experiments were conducted to observe S. melanotheron gill adaptation to abrupt salinity variations in the presence of waterborne DDT, at concentrations detected in their natural habitat. The gills appeared as an important site of DDT conversion to DDD and/or depuration. A 12-days DDT exposure resulted in decreased gill epithelium thickness at all salinities (from fresh- to hypersaline-water), and the structure of gills from freshwater fish was particularly altered, relative to controls. No unbalance in tilapia blood osmolality was observed following DDT exposure, which however caused a decrease in branchial Na(+)-K(+)-ATPase (NKA) activity. Gill cellular NKA expression was reduced in salt-water, together with the expression of the CFTR chloride channel in hypersaline water. Although S. melanotheron seems very resistant (especially in seawater) to short-term waterborne DDT contamination, the resulting alterations of the gill tissue, cells and enzymes might affect longer term respiration, toxicant depuration and/or osmoregulation in highly fluctuating salinities.
authors.affiliation: Université Montpellier, UMR-UM-CNRS-IFREMER-IRD ECOSYM, Equipe Adaptation Ecophysiologique et Ontogenèse, France. virginie_riou@hotmail.com
authors.forename: Virginie
authors.initials: V
authors.lastname: Riou
authors.forename: Awa
authors.initials: A
authors.lastname: Ndiaye
authors.forename: Hélène
authors.initials: H
authors.lastname: Budzinski
authors.forename: Rémi
authors.initials: R
authors.lastname: Dugué
authors.forename: Karyn
authors.initials: K
authors.lastname: Le Ménach
authors.forename: Yan
authors.initials: Y
authors.lastname: Combes
authors.forename: Maryline
authors.initials: M
authors.lastname: Bossus
authors.forename: Jean-Dominique
authors.initials: JD
authors.lastname: Durand
authors.forename: Guy
authors.initials: G
authors.lastname: Charmantier
authors.forename: Catherine
authors.initials: C
authors.lastname: Lorin-Nebel
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects*; D000354:Africa, Western; D000818:Animals; D018118:Chloride Channels / Q000378:metabolism; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000378:metabolism; D003634:DDT / Q000633:toxicity*; D017753:Ecosystem; D004848:Epithelium / Q000378:metabolism / Q000502:physiology; D005618:Fresh Water; D005880:Gills / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D009994:Osmolar Concentration; D054712:Salinity; D012623:Seawater; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D017210:Tilapia / Q000378:metabolism / Q000502:physiology*; D014874:Water Pollutants, Chemical / Q000633:toxicity; D014882:Water-Electrolyte Balance / Q000502:physiology; D015262:Xenobiotics / Q000633:toxicity
chemical_list: D018118:Chloride Channels; D014874:Water Pollutants, Chemical; D015262:Xenobiotics; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D003634:DDT; D000254:Sodium-Potassium-Exchanging ATPase