title: Diversification, evolution and sub-functionalization of 70kDa heat-shock proteins in two sister species of antarctic krill: differences in thermal habitats, responses and implications under climate change.
abstract: BACKGROUND
  A comparative thermal tolerance study was undertaken on two sister species of Euphausiids (Antarctic krills) Euphausia superba and Euphausia crystallorophias. Both are essential components of the Southern Ocean ecosystem, but occupy distinct environmental geographical locations with slightly different temperature regimes. They therefore provide a useful model system for the investigation of adaptations to thermal tolerance.
  
  
  RESULTS
  Initial CTmax studies showed that E. superba was slightly more thermotolerant than E. crystallorophias. Five Hsp70 mRNAs were characterized from the RNAseq data of both species and subsequent expression kinetics studies revealed notable differences in induction of each of the 5 orthologues between the two species, with E. crystallorophias reacting more rapidly than E. superba. Furthermore, analyses conducted to estimate the evolutionary rates and selection strengths acting on each gene tended to support the hypothesis that diversifying selection has contributed to the diversification of this gene family, and led to the selective relaxation on the inducible C form with its possible loss of function in the two krill species.
  
  
  CONCLUSIONS
  The sensitivity of the epipelagic species E. crystallorophias to temperature variations and/or its adaptation to cold is enhanced when compared with its sister species, E. superba. These results indicate that ice krill could be the first of the two species to be impacted by the warming of coastal waters of the Austral ocean in the coming years due to climate change.
authors.affiliation: Sorbonne Universités, UPMC Université Paris 06, UMR 7144 CNRS, Equipe ABICE, Station Biologique de Roscoff, 29680 Roscoff, France; CNRS, UMR 7144, Adaptation et Diversité en Milieu Marin, Station Biologique de Roscoff, 29680 Roscoff, France.
authors.forename: Kévin
authors.initials: K
authors.lastname: Cascella
authors.affiliation: Sorbonne Universités, UPMC Université Paris 06, UMR 7144 CNRS, Equipe ABICE, Station Biologique de Roscoff, 29680 Roscoff, France; CNRS, UMR 7144, Adaptation et Diversité en Milieu Marin, Station Biologique de Roscoff, 29680 Roscoff, France.
authors.forename: Didier
authors.initials: D
authors.lastname: Jollivet
authors.affiliation: Université de Lille1, CNRS UMR8198, Ecoimmunology of Marine Annelids, 59655 Villeneuve d'Ascq, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Papot
authors.affiliation: Sorbonne Universités, UPMC Université Paris 06, UMR 7208 CNRS, Equipe AMEX, 75005 Paris, France; CNRS 7208, BOREA, UPMC Université Paris 06, 75005 Paris, France.
authors.forename: Nelly
authors.initials: N
authors.lastname: Léger
authors.affiliation: Sorbonne Universités, UPMC Université Paris 06, FR 2424 CNRS, ABiMS, Analysis and Bioinformatics for Marine Science, Station Biologique de Roscoff, 29680 Roscoff, France; CNRS, FR 2424, Station Biologique de Roscoff, 29680 Roscoff, France.
authors.forename: Erwan
authors.initials: E
authors.lastname: Corre
authors.affiliation: Sorbonne Universités, UPMC Université Paris 06, UMR 7208 CNRS, Equipe AMEX, 75005 Paris, France; CNRS 7208, BOREA, UPMC Université Paris 06, 75005 Paris, France.
authors.forename: Juliette
authors.initials: J
authors.lastname: Ravaux
authors.affiliation: British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge, CB3 0ET, United Kingdom.
authors.forename: Melody S
authors.initials: MS
authors.lastname: Clark
authors.affiliation: Sorbonne Universités, UPMC Université Paris 06, UMR 7144 CNRS, Equipe ABICE, Station Biologique de Roscoff, 29680 Roscoff, France; CNRS, UMR 7144, Adaptation et Diversité en Milieu Marin, Station Biologique de Roscoff, 29680 Roscoff, France.
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Toullec
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D000864:Antarctic Regions; D060829:Arthropod Proteins / Q000235:genetics* / Q000378:metabolism; D005075:Biological Evolution; D057231:Climate Change; D017753:Ecosystem; D033201:Euphausiacea / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D005810:Multigene Family; D010802:Phylogeny; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013696:Temperature
chemical_list: D060829:Arthropod Proteins; D018840:HSP70 Heat-Shock Proteins
references.citation: Mol Cell Biol. 1998 Apr;18(4):2023-8
references.pmid: 9528774
references.citation: Oecologia. 2007 Dec;154(3):479-84
references.pmid: 17899201
references.citation: Cell Stress Chaperones. 2008 Spring;13(1):51-8
references.pmid: 18347941
references.citation: Proc Natl Acad Sci U S A. 2011 Sep 20;108(38):15936-41
references.pmid: 21911372
references.citation: BMC Evol Biol. 2012;12:170
references.pmid: 22950661
references.citation: Trends Ecol Evol. 2009 Sep;24(9):487-96
references.pmid: 19500875
references.citation: Proc Natl Acad Sci U S A. 2011 May 3;108(18):7625-8
references.pmid: 21482793
references.citation: Proc Biol Sci. 2012 Dec 22;279(1749):5048-57
references.pmid: 22977152
references.citation: PLoS One. 2013;8(8):e71609
references.pmid: 23990964
references.citation: Mol Biol Cell. 2011 Mar 1;22(5):541-54
references.pmid: 21209324
references.citation: Mar Genomics. 2009 Mar;2(1):11-8
references.pmid: 21798167
references.citation: Crit Rev Biochem Mol Biol. 1990;25(4):281-305
references.pmid: 2225910
references.citation: J Exp Biol. 2000 Aug;203(Pt 15):2331-9
references.pmid: 10887071
references.citation: Nature. 2012 Apr 5;484(7392):55-61
references.pmid: 22481358
references.citation: Bioinformatics. 2003 Aug 12;19(12):1572-4
references.pmid: 12912839
references.citation: Cell Stress Chaperones. 2007 Autumn;12(3):275-82
references.pmid: 17915560
references.citation: Nucleic Acids Res. 2005 Jul 1;33(Web Server issue):W557-9
references.pmid: 15980534
references.citation: Ann Rev Mar Sci. 2014;6:469-87
references.pmid: 23987914
references.citation: Trends Ecol Evol. 1996 May;11(5):212-8
references.pmid: 21237811
references.citation: J Biol Chem. 2001 Jul 13;276(28):25791-6
references.pmid: 11325973
references.citation: Biochem Cell Biol. 2010 Apr;88(2):291-300
references.pmid: 20453930
references.citation: BMC Evol Biol. 2007;7:2
references.pmid: 17233905
references.citation: Mol Biol Evol. 2007 Aug;24(8):1586-91
references.pmid: 17483113
references.citation: Philos Trans R Soc Lond B Biol Sci. 2007 Dec 29;362(1488):2191-214
references.pmid: 17553774
references.citation: Biochim Biophys Acta. 2004 Jun 1;1699(1-2):45-56
references.pmid: 15158711
references.citation: Nature. 2010 Sep 2;467(7311):15
references.pmid: 20811427
references.citation: BMC Biol. 2008;6:5
references.pmid: 18211703
references.citation: Biochim Biophys Acta. 2013 Feb;1833(2):388-99
references.pmid: 22705353
references.citation: Cell Stress Chaperones. 2008 Spring;13(1):39-49
references.pmid: 18347940
references.citation: J Exp Biol. 2010 Mar 15;213(6):912-20
references.pmid: 20190116
references.citation: Top Curr Chem. 2013;328:99-153
references.pmid: 22576356
references.citation: Mol Biol Evol. 2001 Jul;18(7):1272-82
references.pmid: 11420366
references.citation: PLoS One. 2011;6(1):e15919
references.pmid: 21253607
references.citation: Annu Rev Biochem. 2006;75:403-33
references.pmid: 16756497
references.citation: Cell Stress Chaperones. 2010 Jan;15(1):83-93
references.pmid: 19496024
references.citation: J Comp Physiol B. 2012 Oct;182(7):899-907
references.pmid: 22547175
references.citation: Biotechnol Lett. 2004 Mar;26(6):509-15
references.pmid: 15127793
references.citation: Philos Trans R Soc Lond B Biol Sci. 2007 Jan 29;362(1477):149-66
references.pmid: 17405211
references.citation: Mol Ecol. 2013 Mar;22(5):1416-30
references.pmid: 23331571
references.citation: Bioinformatics. 2005 May 1;21(9):2104-5
references.pmid: 15647292
references.citation: Trends Genet. 2009 May;25(5):198-202
references.pmid: 19362746
references.citation: Syst Biol. 2003 Oct;52(5):696-704
references.pmid: 14530136
references.citation: J Exp Biol. 2010 Mar 15;213(6):971-9
references.pmid: 20190122
references.citation: Nature. 2004 Nov 4;432(7013):100-3
references.pmid: 15525989
references.citation: Mol Ecol. 2013 Mar;22(6):1494-502
references.pmid: 23599959
references.citation: Nat Rev Genet. 2002 Nov;3(11):827-37
references.pmid: 12415313
references.citation: J Mol Evol. 1996 Feb;42(2):313-20
references.pmid: 8919883
references.citation: Science. 2000 Nov 10;290(5494):1151-5
references.pmid: 11073452
references.citation: Curr Biol. 2008 Feb 26;18(4):282-5
references.pmid: 18302926
references.citation: Fish Shellfish Immunol. 2010 Jan;28(1):56-64
references.pmid: 19815077
references.citation: J Invertebr Pathol. 1997 Nov;70(3):226-33
references.pmid: 9367731
references.citation: Biochim Biophys Acta. 2013 Feb;1833(2):410-6
references.pmid: 22445420
references.citation: Nat Rev Genet. 2009 Oct;10(10):725-32
references.pmid: 19652647
references.citation: Cell Stress Chaperones. 2004 Autumn;9(3):313-23
references.pmid: 15544169
references.citation: J Cell Biol. 2012 Oct 1;199(1):125-35
references.pmid: 23007651
references.citation: Mol Biol Evol. 1986 Sep;3(5):418-26
references.pmid: 3444411
references.citation: Syst Biol. 2003 Oct;52(5):705-16
references.pmid: 14530137
references.citation: Annu Rev Genet. 1993;27:437-96
references.pmid: 8122909
references.citation: Philos Trans R Soc Lond B Biol Sci. 2007 Dec 29;362(1488):2233-58
references.pmid: 17553776
references.citation: Cell Stress Chaperones. 2009 Nov;14(6):649-60
references.pmid: 19404777
references.citation: PLoS One. 2013;8(8):e72246
references.pmid: 23991072
references.citation: Gene. 2007 Jan 15;386(1-2):162-72
references.pmid: 17092661
references.citation: J Mol Evol. 1989 Aug;29(2):170-9
references.pmid: 2509717
references.citation: Mol Phylogenet Evol. 2000 Oct;17(1):26-36
references.pmid: 11020302