title: Investigating heritability of cadmium tolerance in Chironomus riparius natural populations: A physiological approach.
abstract: Physiological responses allow populations to cope with metal contamination and can be involved in the evolution of tolerance under historical metal contamination scenarios. Here we investigate physiological aspects that might be underlying the heritable high tolerance to cadmium (Cd) in two Chironomus riparius populations collected from historically metal contaminated sites in comparison to two populations from reference sites. To evaluate differences in the physiological response to short-term Cd exposure, protein expression profiles, metallothioneins [MTs] and several antioxidant defences such as total glutathione (GSHt), catalase (CAT) and glutathione-S-transferases [GSTs], were measured in all four populations reared for at least 8 generations under laboratory clean conditions. Cd-induced oxidative damage in lipids and energy related parameters (energy consumption and energy reserves) were also assessed. Results showed two major gradients of protein profiles according to Cd concentration and population tolerance. Furthermore, Cd-tolerant populations showed higher baseline levels of MTs and GSHtwhile Cd-sensitive populations, collected from reference sites, showed significant induction of GSHtlevels with Cd exposure that were nonetheless insufficient to avoid increased oxidative damage to lipids. Cd exposure had no clear effects on the antioxidant enzymes or energy reserves but triggered a general increase in energy consumption. Finally, energy consumption was higher in Cd-tolerant populations across experimental conditions. Altogether, results demonstrate that inherited Cd-tolerance in these midge populations is related, at least in part, with different constitutive levels and plasticity of different defence mechanisms confirming the validity of using multiple physiological traits when studying evolution of tolerance.
authors.affiliation: Departamento de Biologia & CESAM, Universidade de Aveiro, 3810-193 Aveiro, Portugal; Conservation Genetics Group, Senckenberg Research Institute and Natural History Museum of Frankfurt, Clamecystrasse 12, 63571 Gelnhausen, Germany. Electronic address: jpedrosa@ua.pt.
authors.forename: João
authors.initials: J
authors.lastname: Pedrosa
authors.affiliation: Departamento de Biologia & CESAM, Universidade de Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: Carlos
authors.initials: C
authors.lastname: Gravato
authors.affiliation: Departamento de Biologia & CESAM, Universidade de Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: Diana
authors.initials: D
authors.lastname: Campos
authors.affiliation: Departamento de Biologia & CESAM, Universidade de Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: Paulo
authors.initials: P
authors.lastname: Cardoso
authors.affiliation: Departamento de Biologia & CESAM, Universidade de Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: Etelvina
authors.initials: E
authors.lastname: Figueira
authors.affiliation: Conservation Genetics Group, Senckenberg Research Institute and Natural History Museum of Frankfurt, Clamecystrasse 12, 63571 Gelnhausen, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Nowak
authors.affiliation: Departamento de Biologia & CESAM, Universidade de Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: Amadeu M V M
authors.initials: AMVM
authors.lastname: Soares
authors.affiliation: Department of Environmental Chemistry (IDAEA-CSIC), Jordi Girona, 18-26, 08034 Barcelona, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Barata
authors.affiliation: Departamento de Biologia & CESAM, Universidade de Aveiro, 3810-193 Aveiro, Portugal. Electronic address: jpestana@ua.pt.
authors.forename: João L T
authors.initials: JLT
authors.lastname: Pestana
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000975:Antioxidants / Q000032:analysis*; D002104:Cadmium / Q000032:analysis* / Q000378:metabolism; D002374:Catalase / Q000737:chemistry; D002683:Chironomidae / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D020869:Gene Expression Profiling; D005978:Glutathione / Q000737:chemistry; D006358:Hot Temperature; D008668:Metallothionein / Q000737:chemistry; D018384:Oxidative Stress; D018675:Toxicity Tests; D014867:Water / Q000737:chemistry
chemical_list: D000975:Antioxidants; D002104:Cadmium; D014867:Water; D008668:Metallothionein; D002374:Catalase; D005978:Glutathione
keywords: Energy allocation; Glutathione; Metal tolerance; Metallothioneins; Oxidative damage; Protein profile