title: Responses of the arcto-boreal krill species Thysanoessa inermis to variations in water temperature: coupling Hsp70 isoform expressions with metabolism.
abstract: Recent studies have indicated a metabolic temperature sensitivity in both the arcto-boreal krill species Thysanoessa inermis and Thysanoessa raschii that may determine these species' abundance and population persistence at lower latitudes (up to 40° N). T. inermis currently dominates the krill community in the Barents Sea and in the high Arctic Kongsfjord. We aimed to increase the knowledge on the upper thermal limit found in the latter species by estimating the CT50value (19.7 °C) (critical temperature at which 50 % of animals are reactive) and by linking metabolic rate measurements with molecular approaches. Optical oxygen sensors were used to measure respiration rates in steps of 2 °C (from 0 to 16 °C). To follow the temperature-mediated mechanisms of passive response, i.e., as a proxy for molecular stress, molecular chaperone heat shock protein 70 (Hsp70) sequences were extracted from a transcriptome assembly, and the gene expression kinetics were monitored during an acute temperature exposure to 6 or 10 °C with subsequent recovery at 4 °C. Our results showed upregulation of hsp70 genes, especially the structurally constitutive and mitochondrial isoforms. These findings confirmed the temperature sensitivity of T. inermis and showed that the thermal stress took place before reaching the upper temperature limit estimated by respirometry at 12 °C. This study provides a baseline for further investigations into the thermal tolerances of arcto-boreal Thysanoessa spp. and comparisons with other krill species under different climatic regimes, especially Antarctica.
authors: Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Section Functional Ecology, Am Handelshafen 12, 27570, Bremerhaven, Germany. kim.huenerlage@awi.de.
authors: Kim
authors: K
authors: Huenerlage
authors: Sorbonne Universités, UPMC Université Paris 06, UMR 7144 CNRS, Equipe ABICE, Station Biologique de Roscoff, Roscoff, France.|CNRS, UMR 7144, Adaptation et Diversité en Milieu Marin, Station Biologique de Roscoff, Roscoff, France.
authors: Kévin
authors: K
authors: Cascella
authors: Sorbonne Universités, UPMC Université Paris 06, FR 2424 CNRS, ABiMS, Station Biologique de Roscoff, Roscoff, France.|CNRS, FR 2424, Station Biologique de Roscoff, Roscoff, France.
authors: Erwan
authors: E
authors: Corre
authors: Sorbonne Universités, UPMC Université Paris 06, UMR 7144 CNRS, Equipe ABICE, Station Biologique de Roscoff, Roscoff, France.|CNRS, UMR 7144, Adaptation et Diversité en Milieu Marin, Station Biologique de Roscoff, Roscoff, France.
authors: Lola
authors: L
authors: Toomey
authors: Department of Biology, National Changhua University of Education, Changhua, 50058, Taiwan.
authors: Chi-Ying
authors: CY
authors: Lee
authors: Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Section Functional Ecology, Am Handelshafen 12, 27570, Bremerhaven, Germany.
authors: Friedrich
authors: F
authors: Buchholz
authors: Sorbonne Universités, UPMC Université Paris 06, UMR 7144 CNRS, Equipe ABICE, Station Biologique de Roscoff, Roscoff, France. jean-yves.toullec@sb-roscoff.fr.|CNRS, UMR 7144, Adaptation et Diversité en Milieu Marin, Station Biologique de Roscoff, Roscoff, France. jean-yves.toullec@sb-roscoff.fr.
authors: Jean-Yves
authors: JY
authors: Toullec
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D033201:Euphausiacea / Q000254:growth & development / Q000378:metabolism*; D018840:HSP70 Heat-Shock Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D059014:High-Throughput Nucleotide Sequencing; D007700:Kinetics; D010802:Phylogeny; D020033:Protein Isoforms / Q000145:classification / Q000235:genetics / Q000378:metabolism; D012313:RNA / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D016415:Sequence Alignment; D017423:Sequence Analysis, RNA; D013696:Temperature; D059467:Transcriptome; D014867:Water / Q000737:chemistry
chemical_list: D018840:HSP70 Heat-Shock Proteins; D020033:Protein Isoforms; D014867:Water; D012313:RNA
keywords: Heat shock; Hsp70 expression; Krill; Metabolic rate; Thysanoessa inermis; Transcriptome