Pituitary hormone mRNA expression in European sea bass Dicentrarchus labrax in seawater and following acclimation to fresh water.
The mRNA expression of pituitary prolactin (prl), growth hormone (gh), somatolactin (sl), proopiomelanocortin (pomc), and gonadotropins (gthI and gthII) was quantified by real-time PCR, in sea bass, Dicentrarchus labrax, adapted for 1 month to seawater (SW) or freshwater (FW). In addition, IGF-I (igfI) mRNA expression in liver and branchial Na+/K+ -ATPase activity were determined. L17 ribosomal protein (rpL17) and elongation factor 1alpha (ef1alpha) were validated as reference genes in real-time PCR in the experimental context. The real-time PCR assays were validated for the different hormone genes considered. Expression of pituitary pomc, gthI, gthII, gh, and liver igfI was not significantly different between FW and SW fish. Pituitary prlwas 4.5-foldhigher in FWthan in SW, whereas pituitary sl was 1.8-fold higher in SW- compared with FW-adapted fish. Gill Na+/K+ -ATPase specific activity was 2.3-fold higher in FW sea bass compared with SW fish. Plasma cortisol levels were 6.5-fold lower in SW- than in FW-adapted specimens. The results are discussed in relation to the osmoregulatory strategy of this euryhaline SW species, which displays features that do not fit present models based on salmonids and FWeuryhaline teleosts.
Varsamos
Stamatis
S
Adaptation Ecophysiologique et Ontogenèse, UMR 5171, GPIA, Université Montpellier II, Place Eugène Bataillon, CC092, 34095 Montpellier Cedex 05, France. varsamos@univ-montp2.fr
Xuereb
Benoît
B
Commes
Thérèse
T
Flik
Gert
G
Spanings-Pierrot
Céline
C
D000222:Adaptation, Physiological / Q000235:genetics*; D000818:Animals; D001492:Bass / Q000378:metabolism*; D017931:DNA Primers / Q000235:genetics; D029941:Fish Proteins / Q000235:genetics; D005618:Fresh Water; D015870:Gene Expression; D005880:Gills / Q000201:enzymology; D006023:Glycoproteins / Q000235:genetics; D006065:Gonadotropins, Pituitary / Q000235:genetics; D013006:Growth Hormone / Q000235:genetics; D006854:Hydrocortisone / Q000097:blood; D010907:Pituitary Hormones / Q000235:genetics*; D011333:Pro-Opiomelanocortin / Q000235:genetics; D011388:Prolactin / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012623:Seawater; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D017931:DNA Primers; D029941:Fish Proteins; D006023:Glycoproteins; D006065:Gonadotropins, Pituitary; D010907:Pituitary Hormones; D012333:RNA, Messenger; C064448:somatolactin protein, fish; D011333:Pro-Opiomelanocortin; D011388:Prolactin; D013006:Growth Hormone; D000254:Sodium-Potassium-Exchanging ATPase; D006854:Hydrocortisone