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Why is temperature important?

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Why is temperature important?

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  1. The effect of variation in dietary energy and protein levels on the lipid class and fatty acid composition of Atlantic salmon (Salmo salar) fed at elevated temperature Matt Miller1&3Julia Barnes1, Rhys Hauler2 , Chris Carter1 & Peter Nichols31School of Aquaculture, TAFI, University of Tasmania,2Skretting, 3CSIRO Marine Research

  2. Why is temperature important? • Salmon Aquaculture under Australian conditions • Australia - higher water temperatures than in the main northern hemisphere Aquaculture areas • Salmon threshold of 20oC • The Effect of Temperature on lipids • Little is known for salmon • Cold water fish need dietary w3 • PUFA have greater flexibility and provide membrane permeability at low temperature

  3. Why lipids? • Major component of fish diets • Important to fish health? • Storage of energy • Vital structural role of cells • Flesh Quality

  4. Major lipid classes in Salmon Polar Lipids (PL)Phosphatidy-choline (PC) 18:0/22:6 Sterols Cholesterol Free Fatty Acids (FFA) 22:6 Triacylglycerols (TAG) 18:0/22:6/20:5

  5. Omega 3 (w3) polyunsaturated fatty acids (PUFA) 1 2 3 DHA (Docosahexaenoic Acid) 22:6w3 EPA (Eicosapentaenoic Acid) 20:5w3 • Omega 3 represents first unsaturation from terminal methyl carbon • Important in human physiology and heath (& farmed fish) • First discovered in 1960s

  6. The experiment • Temperature and growth rate • Threshold 20oC • Julia Barnes Trial • Energy / Protein ratios • Atlantic salmon • Average weights 140g to 460g • 15 week (104 days) • Four feeds • Elevated temperature (19oC)

  7. Analysis Traditional Methods • Growth and weight measurements • FAME by GC and GC-MS • Give information about the length and amount of double bonds in the lipids • Destructive and non regiospecific • Lipid Class by TLC-FID • Gives information about the type of lipid

  8. Results • Over 45 FAME identified • Relationship between Diet and FAME Profile • Lipid Class 80-95%TAG, 8-14% PL • No obvious relationship between Lipid class or FAME with diet and growth data • Decrease in PUFA at higher temperature • FAME • Shift in the ratio of PUFA/SFA • Reduction in the accumulation or production on PUFA at higher temperatures PUFA/SFA • PUFA/SFA ratio for muscle & diets of Atlantic Salmon at different temperatures 12oC Results taken from Bransden et al (2003), 11oC from Bell et al (2003), 10oC from Bell et al (2004) and 19oC from Julia’s protein/energy trial

  9. Analysis New Methods Polar Lipids (PL)Phosphatidy-choline (PC) 18:0/22:6 • Why? • Regiospecific non destructive • LC-MS • Structural (polar) lipid analysis • Functional • 13CNMR • Storage (TAG) Lipid analysis • Energy Triacylglyerols (TAG) 18:0/22:6/20:5

  10. Polar lipids • Phospholipids play a central role in the biochemistry of all living cells • Role in biochemistry is only partly understood • Functional and structural properties • Evolving area of research • Respond in a graded manner

  11. Major polar lipids in salmon membranes Sn1 • Phospholipids • Phosphatidylcholine (PC) • Phosphatidylethanolamine (PE) • Phosphatidylinositol (PI) • Phosphatidylserine (PS) Sn2 PC PI PE PS

  12. Electrospray Ionization Reversed-Phase Liquid Chromatography-Mass Spectrometry (ESI RP-LC-MS) 1 • Direct, fast, convenient and sensitive technique • Quantitative and Qualitative • Regiospecificity is determined • Very complex (20-50 FA x 2 regiospecific positions x 5 PL head groups) 2 >5 xpossible head groups

  13. LC of a Polar lipid fraction Major phosphatidylinositol components of red muscle in Atlantic salmon fed a High Protein Diet

  14. Major phospholipids in salmon By ESI-LC-MS of High Protein diet • Overall Outcomes • First Study • DHA and EPA preferred at the Sn2 position • Generally the larger and/or more unsaturated chain was on the Sn2 position • Major PL for Diet and salmon muscle - PC 16:0/22:6 • Major PL for Gills - PC 16:0/18:1

  15. Regiospecific (why is it important?) Determination of acyl chain by chemical shift difference at the C1 position to determine location on glycerol backbone Non destructive Very complex (20-50 components) 13C Nuclear Magnetic Resonance (13C NMR) C1 Triacylglyerol (TAG) 18:0/22:6/20:5

  16. TAG Regiospecificity in Salmon% in the Sn2 positionsBy 13C NMR spectroscopy EPA Gills 48.8 White Tissue 29.9 Red tissue 21.2 Diet 20.6 DHA Gills 58.3 White Tissue 58.5 Red tissue 61.8 Diet 66.6 33% Probability for DHA in each position

  17. TAG Regiospecificityfor Sn2 positionBy 13C NMR spectroscopy

  18. Julia Barnes UTAS Aquaculture PhD Evan Peacock CSL 13NMR Spectroscopy Noel Davies CSL LC-MS Skretting Acknowledgementsand the assessment of alternative oils • Future PhD work • Stearidonic acid (18:4w3) trial • 2005 Thraustochytrid & Temp trial • 2006 possible GM seed oils trial

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