Heat and copper induced mRNA changes in mussels

Transcriptional profiling of the digestive gland tissue of female mussel Mytilus galloprovincialis exposed to copper along with a temperature gradient Background: Global warming is a major factor that may affect biological organization, especially in marine ecosystems and in coastal areas that are particularly subject to anthropogenic pollution. We evaluated the effects of simultaneous changes in temperature and copper concentrations on lysosomal membrane stability of the blue mussel Mytilus galloprovincialis (Lam.). Temperature and copper exerted additive effects on lysosomal membrane stability, exacerbating the toxic effects of metal cations present in non-physiological concentrations. Mussel lysosomal membrane stability was positively related toscope for growth, indicating possible effects of increasing temperature on mussel populations in metal-polluted areas. To clarify the molecular response to environmental stressors, we used a cDNA microarray with 1,700 sequences to measure the relative transcript abundances in the gills of mussels exposed to copper (40µg/L) and a temperature gradient (16°C, 20°C, and 24°C). In animals exposed only to heat stress, hierarchical clustering of the microarray data revealed three main clusters, which were largely dominated by down-regulation of translation-related differentially expressed genes, drastic up-regulation of folding protein-related genes, and genes involved in chitin metabolism. The response of mussels exposed to copper at 24° C was characterized by an opposite pattern of the genes involved in translation, most of which were up-regulated, as well asthe down-regulation of genes encoding heat shock proteins and microtubule-based movement proteins. Our data provide novel information on the transcriptomic modulations in mussels facing temperature increases and high copper concentrations; these data highlight the risk of marine life exposed to toxic chemicals in the presence of temperature increases due to climate change. Digestive gland tissue from individual animals in different experimental conditions were analyzed in a complete loop design. Dual color competitive hybridizations (Control “16°C” vs “20°C” vs “24°C” vs “16°C+Cu”, “20°C” vs “24°C” vs “20°C+Cu”, “24°C” vs “24°C+Cu”, “16°C+Cu” vs”20°C+Cu” vs “24°C+Cu”; “20°C+Cu” vs “24°C+Cu”) including label swap. Single individuals. Four biological replicates. One replicate per array.