title: Transcriptome profiling of two Iberian freshwater fish exposed to thermal stress.
abstract: The congeneric freshwater fish Squalius carolitertii and S. torgalensis inhabit different Iberian regions with distinct climates; Atlantic in the North and Mediterranean in the South, respectively. While northern regions present mild temperatures, fish in southern regions often experience harsh temperatures and droughts. Previous work with two hsp70 genes suggested that S. torgalensis is better adapted to harsher thermal conditions than S. carolitertii as a result of the different environmental conditions. We present a transcriptomic characterisation of these species' thermal stress responses. Through differential gene expression analysis of the recently available transcriptomes of these two endemic fish species, comprising 12 RNA-seq libraries from three tissues (skeletal muscle, liver and fins) of fish exposed to control (18 °C) and test (30 °C) conditions, we intend to lay the foundations for further studies on the effects of temperature given predicted climate changes. Results showed that S. carolitertii had more upregulated genes, many of which are involved in transcription regulation, whereas S. torgalensis had more downregulated genes, particularly those responsible for cell division and growth. However, both species displayed increased gene expression of many hsps genes, suggesting that they are able to deal with protein damage caused by heat, though with a greater response in S. torgalensis. Together, our results suggest that S. torgalensis may have an energy saving strategy during short periods of high temperatures, re-allocating resources from growth to stress response mechanisms. In contrast, S. carolitertii regulates its metabolism by increasing the expression of genes involved in transcription and promoting the stress response, probably to maintain homoeostasis. Additionally, we indicate a set of potential target genes for further studies that may be particularly suited to monitoring the responses of Cyprinidae to changing temperatures, particularly for species living in similar conditions in the Mediterranean Peninsulas.
authors.affiliation: CE3C - Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, Edifício C2, 3o Piso, Campo Grande, 1749-016 Lisboa, Portugal. Electronic address: tfjesus@fc.ul.pt.
authors.forename: Tiago Filipe
authors.initials: TF
authors.lastname: Jesus
authors.affiliation: Instituto de Medicina Molecular, Av. Prof. Egas Moniz, Edf. Egas Moniz, Sala P3B-34, 1649-028 Lisboa, Portugal.
authors.forename: Ana Rita
authors.initials: AR
authors.lastname: Grosso
authors.affiliation: Laboratório de Ecofisiologia e Evolução Molecular, Instituto Nacional de Pesquisas da Amazônia (INPA), Manaus, AM, Brazil.
authors.forename: Vera Maria Fonseca
authors.initials: VMF
authors.lastname: Almeida-Val
authors.affiliation: CE3C - Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, Edifício C2, 3o Piso, Campo Grande, 1749-016 Lisboa, Portugal.
authors.forename: Maria Manuela
authors.initials: MM
authors.lastname: Coelho
mesh_terms: D000818:Animals; D003530:Cyprinidae / Q000235:genetics*; D029941:Fish Proteins / Q000235:genetics*; D020869:Gene Expression Profiling; D006360:Heat-Shock Proteins / Q000235:genetics; D018869:Heat-Shock Response; D018482:Muscle, Skeletal / Q000378:metabolism; D013045:Species Specificity; D059467:Transcriptome
chemical_list: D029941:Fish Proteins; D006360:Heat-Shock Proteins
keywords: Cyprinidae; Gene expression; RNA-seq; Squalius; Temperature