Karine Salin1*, Emmanuel Dubillot2, Salomé Ducos2, Nicolas
Graziano2,3, Fabienne Le Grand3, Philippe Soudant3,
Christel Lefrançois2, José Luis Zambonino Infante1, Marie
Vagner2
1 Ifremer, Unité de Physiologie Fonctionnelle des Organismes
Marins – Marine Environmental Science Laboratory UMR 6530, BP70,
Plouzané, 29280, France; 2 UMR 7266 LIENSs, 2 rueOlympe de Gouges
17000 La Rochelle, France; 3 CNRS, Marine Environmental Science
Laboratory –UMR 6530, BP70, Plouzané, 29280, France; 4 UBO, Marine
Environmental ScienceLaboratory – LEMAR UMR 6530, BP70, Plouzané,
29280, France
*[email protected]
Depletion in dietary Omega 3 fatty acid and mitochondrial
efficiency in mullet
n-3 HUFA content of fish depends on their diet
OBJECTIVES
Determine the effects of depletion in dietary n-3 HUFA in fish
on:
1. Animal performance: growth rate
2. Mitochondrial performance: efficiency to convert energy
3. Membrane composition: n-3 HUFA content
REFERENCESVagner, M., et al. (2014). "Reduced n-3 highly
unsaturated fatty acids dietary content expected with global change
reduces the metabolic capacity of the golden grey mullet." Marine
Biology 161(11): 2547-2562.Salin, K., et al. (2016). "Simultaneous
measurement of mitochondrial respiration and ATP production in
tissue homogenates and calculation of effective P/O ratios."
Physiological Reports 4(20): e13007.
DISCUSSION
Interestingly, under depleted diet treatment, individuals tended
to perform better: faster growth for equal caloric content in the
diet (Fig.2), associated to trends for higher mitochondrial
efficiency (Fig.3).
This suggests that the low n-3 HUFA diet could have a beneficial
effect on the mitochondrial efficiency, and in turn on animal
growth.
Negative effect of the n-3 HUFA diet on the growth rate in
mullet has been found in previous studies, but the duration of the
food treatment was higher (5 months instead of 2 months here,
Vagner et al. 2014).
While experimentally induced depletion in membrane content in
n-3 HUFA tended to affect the whole-organism and subcellular
performance, these effects were not significant. Repeating the
experiment with a large sample size will help validating or
rejecting the trends.
Further direction will be to test whether the effect of the diet
composition on the cell membrane HUFA content is tissue-specific
(is the membrane fatty acid composition in the liver influenced by
the diet?) and membrane-specific (are the mitochondrial membrane
depleted in n-3 HUFA in the mitochondria of low n-3 HUFA
fish?).
Risk of depletion of n-3 HUFA availability in the marine
environment
GLOBAL CLIMATE CHANGE
UV temperature pH
PHYTOPLANKTON
Growth n-3 HUFA synthesis
n-3 HUFA AVAILABILITY
n-3 HUFA in Diet
INTRODUCTION
Essential Omega-3 long chain highly unsaturated fatty acids (n-3
HUFA): Critical for growth, reproduction and survival.
Structure
ESSENTIAL FOR CELL:
Function
METHODS
• Maintainance of wild caught mullet Liza aurata under HIGH n-3
HUFA (1.2 % HUFA, HH, n=11) and LOW n-3 HUFA (0.2 % HUFA, LH, n=12
) diet over 2 months (Vagner et al. 2014).
• Measurement of body size
• Assay of mitochondrial efficiency (Fig 1.; Salin et al.
2016)
(i) Respiratory control Ratio (RCR): the ratio of the
respiration supporting ATP synthesis (OXPHOS) to the respiration
wasted to offset the proton leak (LEAK)
(ii) ATP/O ratio: the amount of ATP generated per molecule of
oxygen consumed during OXPHOS respiration
Figure 1: Steps to asses the mitochondrial performance in liver
and muscle of Mullet.A. Liver and muscle were collected for
analyses of mitochondrial properties. B. Mitochondria were isolated
bydifferential centrifugations. C. Isolated mitochondria were added
in assay buffer in the respirometry chambersequipped with
fluorescent sensors (D.). E. A sequential substrate/inhibitor
addition protocol was run: the rates ofOXPHOS respiration and ATP
production were assessed by adding nonlimiting ADP to the chamber
containing thesubstrates pyruvate, malate and succinate, as well as
free magnesium and Magnesium Green probe. LEAK respirationwas then
measured by inhibiting ATP synthesis through the addition of
carboxyatractyloside.
A. B.
Proton LEAK
A.
B. C.
D.
E.
RESULTS
Figure 2: Effect of the food treatment on the specific rate of
growth in MulletFish on the depleted n-3 HUFA diet tend to grow
more slowly in comparison to those on high n-3 HUFA diet but this
effect was not significant (p= 0.059).
Figure 3: food treatment effects on RCR and ATP/O ratio of the
liver mitochondria of mullet. A. Depletion in dietary n-3 HUFA
seems to have led to an increase in RCR but this trend was non
significant (p =0.228) and was driven by the differences in body
mass between LH and HH treatment (p=0.044). B. Depletion in dietary
n-3 HUFA led to a tendency for the ATP/O ratio to increase in LH
compared with HH but this effect was not significant (p =0.131)
.
Muscle membrane composition: The membrane fatty acid composition
in musclewas constrained by the fatty acid profile of the diet,
i.e. low n-3 HUFA fish havelower levels of n-3 HUFA in their
biological membranes.
ACKNOWLEDGEMENTWe acknowledge financial support from the Contrat
de Plan Etat-Région, the CNRS and the European Regional Development
Fund.
mailto:*[email protected]
