Increased seawater temperatures cause temporal shifts in catabolic pathways of Antarctic krill Euphausia superba
Tobias Mattfeldt1, So Kawaguchi2, Mathias Teschke1, Natasha Waller2, Bettina Meyer1
1 Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Germany
2 Department of Environment and Heritage, Australian Antarctic Division, Australia
Photo: J. v. Franecker
Feb 27th 2015, ASLO Aquatic Sciences Meeting
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2/18 Background
Lisa Roberts CC BY-‐NC-‐SA 3.0
- Highly abundant: 170-379 Mt
(Siegel, 2005; Atkinson et al., 2009)
- Important grazer & prey item:
top-down & bottom-up control
(Everson, 2000; Pikitch et al., 2012)
- Growing commercial interest:
largest underexploited stock
(Garcia & Rosenberg, 2010; Nicol et al., 2012)
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3/18 Background
Lisa Roberts CC BY-‐NC-‐SA 3.0
Quetin & Ross, 1991
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3/18 Background
Lisa Roberts CC BY-‐NC-‐SA 3.0
Quetin & Ross, 1991
Spawning Lipid Storage Over-wintering
Maturation
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4/18 Background
Lisa Roberts CC BY-‐NC-‐SA 3.0
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4/18 Background
Whitehouse et al., 2008
2/x Contents
Experimental Design
5/18 Exp. Design
6/18 Exp. Design
Experimental Setup
7/18 Exp. Design
Sampling Scheme
Weeks
7/18 Exp. Design
Sampling Scheme
Weeks
18 x
18 x
18 x
7/18 Exp. Design
Sampling Scheme
Weeks
18 x 18 x 18 x
24 x 6 x 6 x 6 x
8/18 Results
Respiration
9/18 Results
after Brett & Groves, 1979
caloric equivalent during catabolism of protein/lipid is 19.4 J per ml O2
Respiration -> Energy Requirement
9/18 Results
How are energy demands met?
Respiration -> Energy Requirement
Gerhard Michal
10/18 Results
TCA cycle
beta oxidation Glycolysis
Gerhard Michal
10/18 Results
TCA cycle
beta oxidation
malate
dehydrogenase
Gerhard Michal
citrate synthase pyruvate
kinase
3-hydroxyacyl-CoA- dehydrogenase
10/18 Results
Glycolysis
11/18 Results
Malate Dehydrogenase MDH
- key enzyme in TCA cycle
- also involved in other
pathways (gluconeogenesis, malate-aspartate-shuttle)
12/18 Results
Citrate Synthase CS
- pace-making first reaction in the cycle
- marker for aerobic capacity
- acts as central crossing point for various pathways
- entry point for fat synthesis
(acetyl-CoA to cytosol via citrate)
13/18 Results
Pyruvate Kinase PK
- key enzyme in glycolytic pathway
- constitutes primary metabolic intersection (Munoz 2003)
- suggested to play an important role in the transition to
anaerobic metabolism (Vial et al.
1992)
14/18 Results
3-Hydroxyacyl-CoA-DH HOAD
- 3rd step in beta oxidation
- marker enzyme for utilization of lipids
15/18 Conclusion
Carbohydrate Catabolism
pyruvate kinase
-
no onset of anaerobiosis
-
still within aerobic capacity
citrate synthase
5°C 7°C
15/18 Conclusion
Carbohydrate Catabolism
Additional role of MDH: malate-aspartate shuttle? gluconeogenesis?
malate dehydrogenase pyruvate kinase citrate synthase
5°C 7°C
16/18 Conclusion
Lipid Catabolism
3-hydroxyacyl-CoA-DH
-increased oxidation of
lipids
16/18 Conclusion
Lipid Catabolism
3-hydroxyacyl-CoA-DH
-
normalization to CS as central crossing point in
metabolism (Windisch et al., 2011)
-
increase in ratio hints at tendency towards lipid oxidation, NOT lipid
synthesis
-
increased oxidation of
lipids
17/18 Conclusion
Control Treatment
Energy may lack elsewhere, for example maturation
17/18 Conclusion
Control Treatment
Krill relies on productive summer months to accumulate lipid
reserves for winter - increased lipid oxidation may impede the
build-up of these crucial reserves - overwinter-ability affected
Energy may lack elsewhere, for example maturation
18/18
Thank You!
Lisa Roberts CC BY-‐NC-‐SA 3.0
