Tag Archive for: Mitochondrial efficiency

Relationship between membrane n-3 HUFA content and mitochondrial efficiency

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The relationship between membrane fatty acid content and mitochondrial efficiency differs within- and between- omega-3 dietary treatments

 

Abstract

An important, but underappreciated, consequence of climate change is the reduction in crucial nutrient production at the base of the marine food chain: the long-chain omega-3 highly unsaturated fatty acids (n-3 HUFA). This can have dramatic consequences on consumers, such as fish as they have limited capacity to synthesise n-3 HUFA de novo. The n-3 HUFA, such as docosahexaenoic acid (DHA, 22:6n-3) and eicosapentaenoic acid (EPA, 20:5n-3), are critical for the structure and function of all biological membranes. There is increasing evidence that fish will be badly affected by reductions in n-3 HUFA dietary availability, however the underlying mechanisms remain obscure. Hypotheses for how mitochondrial function should change with dietary n-3 HUFA availability have generally ignored ATP production, despite its importance to a cell’s total energetics capacity, and in turn, whole-animal performance. Here we (i) quantified individual variation in mitochondrial efficiency (ATP/O ratio) of muscle and (ii) examined its relationship with content in EPA and DHA in muscle membrane of a primary consumer fish, the golden grey mullet Chelon auratus, receiving either a high or low n-3 HUFA diet. Mitochondria of fish fed on the low n-3 HUFA diet had higher ATP/O ratio than those of fish maintained on the high n-3 HUFA diet. Yet, mitochondrial efficiency varied up about 2-fold among individuals on the same dietary treatment, resulting in some fish consuming half the oxygen and energy substrate to produce the similar amount of ATP than conspecific on similar diet. This variation in mitochondrial efficiency among individuals from the same diet treatment was related to individual differences in fatty acid composition of the membranes: a high ATP/O ratio was associated with a high content in EPA and DHA in biological membranes. Our results highlight the existence of interindividual differences in mitochondrial efficiency and its potential importance in explaining intraspecific variation in response to food chain changes.

 

Figure 2: A golden grey mullet’s mitochondrial efficiency of ATP production under Low and High n-3 HUFA diet is related to the n-3 content (docosahexaenoic acid (DHA, 22:6n-3) and eicosapentaenoic acid (EPA, 20:5n-3)) of its membrane phospholipids, with individuals that have mitochondria with higher ability to make ATP had higher membrane n-3 content.

 

Reference

Salin K, Mathieu-Resuge M, Graziano N, Dubillot E, Le Grand F, Soudant P, Vagner M. 2020. The relationship between membrane fatty acid content and mitochondrial efficiency differs within- and between- omega-3 dietary treatments. Marine Environmental Research:105205.

https://doi.org/10.1016/j.marenvres.2020.105205

Effects of Omega 3 depletion on marine fish: ecophysiological approach

There is increasing evidence that climate change might critically deplete nutrients in food web of marine fish. In particular, a reduction in the production of Omega 3 (Ω3) in phytoplankton as a result of ocean warming can have negative impact on fish. Ω3 are fatty acids that are essential components of cell membranes. Such depletion in Ω3 in membranes can impair fish performance, however, the underlying mechanisms remain obscure. Mitochondria are likely to be involved in the fish response to Ω3 depletion. Changes in the composition of membrane fatty acid of mitochondria affect their efficiency. Organisms that have less efficient mitochondria are less able to maintain ATP [Adenosine TriPhosphate) production, a feature that is likely to affect the overall animal performance. This PhD work will therefore evaluate how the reduction in dietary Ω3 affect mitochondrial function and in turn the performance of a fish, the mullet (Liza aurata)

Thesis supervisor: José-Luis Zambonino-Infante

Thesis co-supervisor: Karine Salin

Read the terms and conditions and download the application form here:

https://wwz.ifremer.fr/Actualites-et-Agenda/Toutes-les-actualites/Theses-2019

Applications must be submitted before 30 June 2019, but we strongly encourage you to announce your intention to apply as soon as possible, by contacting the persons in charge of the subject.

Tag Archive for: Mitochondrial efficiency

Quemeneur Jean-Baptiste thèse