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ABSTRACT: We have investigated the effects of a 3-thia fatty acid (TTA) and of temperature on the fatty acid (FA) metabolism of Atlantic salmon (Salmo salar). One experiment investigated the activity of the peroxisomal beta-oxidation enzyme, acyl-CoA oxidase (ACO), and the incorporation of TTA into phospholipid (PL) molecular species. Salmon hepatocytes in culture were incubated either without TTA (control(spades)) or with 0.8 mM TTA (TTA(spades)) in a short term (48 h) temperature study at 5 degrees C and at 12 degrees C. TTA was incorporated into the four PL classes studied: phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI) and phosphatidylserine (PS). TTA was preferentially esterified with 18:1, 16:1, 20:4 and 22:6 in the PLs. Hepatocytes incubated with TTA had higher ACO activity at 5 degrees C than at 12 degrees C. In a second experiment salmon were fed a diet based on fish meal-fish oil without any TTA added (control) or a fish meal-fish oil diet supplemented with 0.6% TTA for 8 weeks at 12 degrees C and 20 weeks at 5 degrees C. At the end of the feeding trial, hepatocytes from fish acclimated to high or low temperatures were isolated from both dietary groups and incubated with either [1-(14)C]18:1 n-9 or [1-(14)C]20:4 n-3 at 5 degrees C or 12 degrees C. Radiolabelled 18:1 n-9 was mainly esterified into neutral lipids (NL), whereas [1-(14)C]20:4 n-3 was mainly esterified into PL at both temperatures. The rate of elongation of [1-(14)C]18:1 n-9 to 20:1 n-9 was twice as high in hepatocytes from fish fed the control diet than it was in hepatocytes from fish fed the TTA diet, at both temperatures. The amount of [1-(14)C]20:4 n-3 converted to 22:6 n-3 was approximately the same in hepatocytes from the two dietary groups, but there was a tendency to higher production of 22:6 n-3 at the lower temperature. Oxidation of [1-(14)C]18:1 n-9 to acid soluble products (ASP) and CO(2) was approximately 10-fold greater in hepatocytes kept at 5 degrees C than in those kept at 12 degrees C and the main oxidation products formed were acetate, oxaloacetate and malate.
Comparative Biochemistry and Physiology Part B Biochemistry and Molecular Biology 10/2006; 145(1):68-80. · 1.92 Impact Factor
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ABSTRACT: The white muscle of Atlantic salmon metabolizes FA with different chain lengths and different saturations at different rates, but few details are available on the processes involved or the products formed. We have investigated how multinucleated muscle cells (myotubes) in culture metabolize [1-(14)C]8:0, [1-(14)C]18:1n-9, and [1-(14)C]20:5n-3. The myotubes were formed by the differentiation of isolated myosatellite cells from the white skeletal muscle of salmon fry. Almost all (98%) of the [1-(14)C]8:0 substrate was oxidized to acid-soluble products (ASP) and (14)CO2 after 48 h of incubation, whereas only approximately 50% of the [1-(14)C]18:1n-9 and [1-(14)C]20:5n-3 substrates were oxidized. However, only one cycle of beta-oxidation was measured by the method used. For all three substrates, the main ASP were acetate and a combined fraction of oxaloacetate and malate. Nearly twice as much radioactivity from the [1-(14)C]20:5n-3 substrate was found in the cellular lipids as radioactivity from [1-(14)C]18:1n-9, indicating that [1-(14)C]20:5n-3 was taken up into muscle cells more rapidly than [1-(14)C]18:1n-9. Approximately 10% of the added [1-(14)C]20:5n-3 substrate and 5% of the added [1-(14)C]18:1n-9 substrate was secreted from the muscle cells into the culture media as esterified lipids. Immunocytochemical staining showed that the cells synthesized apolipoprotein A-I. Differentiated muscle cells also expressed peroxisome proliferator-activated receptor alpha (PPARalpha) and PPARbeta, two transcription factors that are involved in regulating beta-oxidation.
Lipids 08/2004; 39(7):649-58. · 2.13 Impact Factor
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ABSTRACT: We have investigated the effects of a 3-thia fatty acid (TTA) and of temperature on the fatty acid (FA) metabolism of Atlantic salmon (Salmo salar). One experiment investigated the activity of the peroxisomal β-oxidation enzyme, acyl-CoA oxidase (ACO), and the incorporation of TTA into phospholipid (PL) molecular species. Salmon hepatocytes in culture were incubated either without TTA (control♠) or with 0.8 mM TTA (TTA♠) in a short term (48 h) temperature study at 5 °C and at 12 °C. TTA was incorporated into the four PL classes studied: phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI) and phosphatidylserine (PS). TTA was preferentially esterified with 18:1, 16:1, 20:4 and 22:6 in the PLs. Hepatocytes incubated with TTA had higher ACO activity at 5 °C than at 12 °C. In a second experiment salmon were fed a diet based on fish meal–fish oil without any TTA added (control) or a fish meal–fish oil diet supplemented with 0.6% TTA for 8 weeks at 12 °C and 20 weeks at 5 °C. At the end of the feeding trial, hepatocytes from fish acclimated to high or low temperatures were isolated from both dietary groups and incubated with either [1-14C]18:1 n-9 or [1-14C]20:4 n-3 at 5 °C or 12 °C. Radiolabelled 18:1 n-9 was mainly esterified into neutral lipids (NL), whereas [1-14C]20:4 n-3 was mainly esterified into PL at both temperatures. The rate of elongation of [1-14C]18:1 n-9 to 20:1 n-9 was twice as high in hepatocytes from fish fed the control diet than it was in hepatocytes from fish fed the TTA diet, at both temperatures. The amount of [1-14C]20:4 n-3 converted to 22:6 n-3 was approximately the same in hepatocytes from the two dietary groups, but there was a tendency to higher production of 22:6 n-3 at the lower temperature. Oxidation of [1-14C]18:1 n-9 to acid soluble products (ASP) and CO2 was approximately 10-fold greater in hepatocytes kept at 5 °C than in those kept at 12 °C and the main oxidation products formed were acetate, oxaloacetate and malate.
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology.
