title: Influence of long (16L:8D) and short (8L:16D) photoperiods on blood metabolites and hepatic metabolism in Olive flounder, Paralichthys olivaceus.
abstract: In the present study the influence of long photoperiod (LP, 16L:8D) and short photoperiod (SP, 8L:16D) on hepatic energy metabolism in the olive flounder (Paralichthys olivaceus) was investigated. Flounders were maintained under LP or SP conditions for 2 weeks then plasmatic and hepatic parameters were assessed. At the plasmatic level, the concentration of cortisol was enhanced in flounder maintained under LP compared to SP. Alkaline phosphatase (ALP), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) enzyme activities in plasma also increased in LP flounder. There was no significant difference in plasma glucose levels between the two experimental groups. Plasma osmotic pressure, Na and Cl levels were significantly higher in LP compared to the SP group. In liver, a significant decrease of triglycerides together with an increase in glycogen was observed in the LP group. Hepatic hsl and pepck and muscle hsl mRNA expression in LP was significantly higher in the SP group. Overall the results indicate that the LP treatment caused a mild stress response and increased hepatic energy metabolism in the flounder, which in turn could affect osmoregulation. In conclusion, it would appear that LP treatment can adversely influence hepatic energy metabolism in adult olive flounder under fasting condition.
authors.affiliation: Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai, 201306 China ; College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, 201306 China.
authors.forename: Huafeng
authors.initials: H
authors.lastname: Zou
authors.affiliation: College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, 201306 China.
authors.forename: Xianshou
authors.initials: X
authors.lastname: Bai
authors.affiliation: College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, 201306 China.
authors.forename: Yuhong
authors.initials: Y
authors.lastname: Feng
authors.affiliation: College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, 201306 China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai, 201306 China ; College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, 201306 China.
authors.forename: Youji
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai, 201306 China ; College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, 201306 China.
authors.forename: Weiqun
authors.initials: W
authors.lastname: Lu
keywords: Energy metabolism; Hepatic parameters; Olive flounder; Photoperiod; hsl; pepck