Metabolic and molecular stress responses of gilthead seam bream Sparus aurata during exposure to low ambient temperature: an analysis of mechanisms underlying the winter syndrome.
The winter syndrome in the gilthead sea bream Sparus aurata indicates that the species is exposed to critically low temperatures in Mediterranean aquaculture in winter. The present study of metabolic patterns and molecular stress responses during cold exposure was carried out to investigate this "disease", in light of the recent concept of oxygen and capacity limited thermal tolerance. The metabolic profile of fuel oxidation was examined by determining the activities of the enzymes hexokinase (HK), aldolase (Ald), pyruvate kinase (PK), L-lactate dehydrogenase (L-LDH), citrate synthase (CS), malate dehydrogenase (MDH) and 3-hydroxyacyl CoA dehydrogenase (HOAD) in heart, red and white muscle after exposure to temperatures of 10, 14 and 18°C. Especially, the increase in LDH activity combined with the accumulation of L-lactate in tissues indicates that temperatures below 14°C are critical for Sparus aurata and stimulate the anaerobic component of metabolism. Increase in the activity of HOAD suggests that oxidation of free fatty acids might contribute to ATP turnover at low temperatures. The expression of Hsp70 and Hsp90 in all tissues examined revealed a cellular stress response during cooling below 18°C. In the light of winter temperatures in S. aurata cultures around 10°C, our data suggest that the fish are exposed to stressful conditions at the low end of their thermal tolerance window. These conditions likely impair the aerobic capacity of the fish, compromise the rates of growth and reproduction and may contribute to elicit pathological conditions.
Kyprianou
Themis-Dimitrios
TD
Laboratory of Animal Physiology, Department of Zoology, Faculty of Sciences, School of Biology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece.
Pörtner
Hans O
HO
Anestis
Andreas
A
Kostoglou
Basile
B
Feidantsis
Konstantinos
K
Michaelidis
Basile
B
D000064:Acclimatization / Q000502:physiology*; D000818:Animals; D017756:Aquaculture; D001786:Blood Glucose / Q000032:analysis; D003080:Cold Temperature / Q000009:adverse effects; D004734:Energy Metabolism; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism; D019344:Lactic Acid / Q000097:blood / Q000378:metabolism; D008099:Liver / Q000201:enzymology / Q000378:metabolism; D018485:Muscle Fibers, Skeletal / Q000201:enzymology / Q000378:metabolism; D009206:Myocardium / Q000201:enzymology / Q000378:metabolism; D021541:Sea Bream / Q000097:blood / Q000502:physiology*; D012621:Seasons; D012623:Seawater; D013997:Time Factors; D014280:Triglycerides / Q000097:blood
D001786:Blood Glucose; D018840:HSP70 Heat-Shock Proteins; D018841:HSP90 Heat-Shock Proteins; D014280:Triglycerides; D019344:Lactic Acid