title: Differential gene expression associated with euryhalinity in sea bream (Sparus sarba).
abstract: Certain fish have the remarkable capability of euryhalinity, being able to withstand large variations in salinity for indefinite periods. Using the highly euryhaline species, silver sea bream (Sparus sarba), as an experimental model, some of the molecular processes involved during ion regulation (Na+-K+-ATPase), cytoprotection [heat shock protein (hsp) 70], and growth (somatotropic axis) were studied. To perform these studies, seven key genes involved in these processes were cloned, and the tissue-specific expression profiles in fish adapted to salinities of 6 parts per thousand (ppt; hypoosmotic), 12 ppt (isoosmotic), 33 ppt (seawater), and 50 ppt (hypersaline) were studied. In gills, the transcriptional and translational expression profiles of Na+-K+-ATPase alpha- and beta-subunit genes were lowest in isoosmotic-adapted fish, whereas in kidneys the expression of the beta-subunit increased in seawater- and hypersaline-adapted groups. The hsp70 multigene family, comprising genes coding for heat shock cognate (hsc70), inducible heat shock protein (hsp70), and a heat shock transcription factor (hsf1), was found to be highly upregulated in gills of seawater- and hypersaline-adapted fish. In liver, hsc70 expression was lowest in isoosmotic groups, and in kidneys the hsp70 multigene family remained unchanged over the salinity range tested. The regulation of the somatotropic axis was studied by measuring pituitary growth hormone expression and liver IGF-I expression in salinity-adapted fish. The expression amounts of both genes involved in the somatotropic axis were highest in fish maintained at an isoosmotic salinity. The results of this study provide new information on key molecular processes involved in euryhalinity of fish.
authors.affiliation: Department of Biology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, China.
authors.forename: Eddie E
authors.initials: EE
authors.lastname: Deane
authors.forename: Norman Y S
authors.initials: NY
authors.lastname: Woo
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D000818:Animals; D003001:Cloning, Molecular; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000235:genetics; D005786:Gene Expression Regulation / Q000235:genetics* / Q000502:physiology*; D005880:Gills / Q000201:enzymology; D006128:Growth / Q000502:physiology; D013006:Growth Hormone / Q000235:genetics / Q000502:physiology; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D000076249:Heat Shock Transcription Factors; D006706:Homeostasis / Q000235:genetics*; D007334:Insulin-Like Growth Factor I / Q000235:genetics; D007668:Kidney / Q000201:enzymology; D010473:Perciformes / Q000235:genetics* / Q000502:physiology*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012965:Sodium Chloride / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000235:genetics / Q000378:metabolism; D013312:Stress, Physiological / Q000503:physiopathology; D014157:Transcription Factors
chemical_list: D017931:DNA Primers; D004268:DNA-Binding Proteins; D018840:HSP70 Heat-Shock Proteins; D000076249:Heat Shock Transcription Factors; D012333:RNA, Messenger; D014157:Transcription Factors; D012965:Sodium Chloride; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D000254:Sodium-Potassium-Exchanging ATPase