Fatty Acid Composition Of Mitochondrial Phospholipids Research Articles

Dietary lipid quality and mitochondrial membrane composition in trout: responses of membrane enzymes and oxidative capacities

To examine whether membrane fatty acid (FA) composition has a greater impact upon specific components of oxidative phosphorylation or on overall properties of muscle mitochondria, rainbow trout (Oncorhynchus mykiss) were fed two diets differing only in FA composition. Diet 1 was enriched in 18:1n-9 and 18:2n-6 while Diet 2 was enriched in 22:6n-3. The FA composition of mitochondrial phospholipids was strongly affected by diet. 22:6n-3 levels were twice as high (49%) in mitochondrial phospholipids of fish fed Diet 2 than in those fed Diet 1. 18:2n-6 content of the phospholipids also followed the diets, whereas 18:1n-9 changed little. All n-6 FA, most notably 22:5n-6, were significantly higher in fish fed Diet 1. Nonetheless, total saturated FA, total monounsaturated FA and total polyunsaturated FA in mitochondrial phospholipids varied little. Despite a marked impact of diet on specific FA levels in mitochondrial phospholipids, only non-phosphorylating (state 4) rates were higher in fish fed Diet 2. Phosphorylating rates (state 3), oxygen consumption due to flux through the electron transport chain complexes as well as the corresponding spectrophotometric activities did not differ with diet. Body mass affected state 4 rates and cytochrome c oxidase and F 0 F 1 ATPase activities while complex I showed a diet-specific effect of body mass. Only the minor FA that were affected by body mass were correlated with functional properties. The regulated incorporation of dietary FA into phospholipids seems to allow fish to maintain critical membrane functions even when the lipid quality of their diets varies considerably, as is likely in their natural environment.

Diet and performance in the scallop,Argopecten purpuratus: force production during escape responses and mitochondrial oxidative capacities

We examined whether escape response performance and mitochondrial capacities could reveal differences created by feeding scallops, Argopecten purpuratus, mono-specific algal diets composed of either Chaetoceros calcitrans or Isochrysis galbana (variety T. iso) hereafter T. iso. Before and after feeding scallops with these diets, we assessed force production in vivo to evaluate escape response performance (initial and repeat). We measured oxidative capacities of mitochondria isolated from the adductor muscle and from the male and female portions of the gonad. Initial escape response performance was reduced more by the C. calcitrans diet than by the T. iso diet. Repeat escape responses, which require aerobic recuperation, were reduced by both treatments. The oxidative capacity of mitochondria isolated from muscle and female gonad was markedly lower in scallops fed C. calcitrans than in those fed T. iso. Flux through complex I–IV and through complex IV was also lower in mitochondria from muscle of scallops fed C. calcitrans than in those fed T. iso. Muscle aerobic capacity, assessed by citrate synthase activity, was lower in scallops fed C. calcitrans than in those fed T. iso. Despite the marked differences in fatty acid (FA) composition of the algal diets, the FA composition of mitochondrial phospholipids differed little between scallops fed C. calcitrans and those fed T. iso. Both escape response behaviour and mitochondrial capacities changed with feeding mono-specific diets. The simplicity of measurements of scallop escape responses suggests this as a practical means of evaluating the status of scallops for the two monoalgal diets tested.

Dietary supplementation with docosahexaenoic acid, but not eicosapentanoic acid, remodels cardiac mitochondrial phospholipid fatty acid composition and prevents permeability transition

Dietary supplementation with docosahexaenoic acid, but not eicosapentanoic acid, remodels cardiac mitochondrial phospholipid fatty acid composition and prevents permeability transition

Dietary supplementation with docosahexaenoic acid, but not eicosapentaenoic acid, dramatically alters cardiac mitochondrial phospholipid fatty acid composition and prevents permeability transition

Treatment with the ω-3 polyunsaturated fatty acids (PUFAs) docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) exerts cardioprotective effects, and suppresses Ca 2+-induced opening of the mitochondrial permeability transition pore (MPTP). These effects are associated with increased DHA and EPA, and lower arachidonic acid (ARA) in cardiac phospholipids. While clinical studies suggest the triglyceride lowering effects of DHA and EPA are equivalent, little is known about the independent effects of DHA and EPA on mitochondria function. We compared the effects of dietary supplementation with the ω-3 PUFAs DHA and EPA on cardiac mitochondrial phospholipid fatty acid composition and Ca 2+-induced MPTP opening. Rats were fed a standard lab diet with either normal low levels of ω-3 PUFA, or DHA or EPA at 2.5% of energy intake for 8 weeks, and cardiac mitochondria were isolated and analyzed for Ca 2+-induced MPTP opening and phospholipid fatty acyl composition. DHA supplementation increased both DHA and EPA and decreased ARA in mitochondrial phospholipid, and significantly delayed MPTP opening as assessed by increased Ca 2+ retention capacity and decreased Ca 2+-induced mitochondria swelling. EPA supplementation increased EPA in mitochondrial phospholipids, but did not affect DHA, only modestly lowered ARA, and did not affect MPTP opening. In summary, dietary supplementation with DHA but not EPA, profoundly altered mitochondrial phospholipid fatty acid composition and delayed Ca 2+-induced MPTP opening.

Higher Unsaturation and Peroxidizability Indices in Caloric Restricted <i>Drosophila melanogaster</i> than in Control

The biochemical processes involved in ageing are poorly understood. One of the general approaches to understanding the mechanism of ageing is to study the effect of experimental manipulations on life-span and the properties that are affected by them. Some of these experimental manipulations are caloric restriction and genetic manipulations. Although these manipulations have been used many times and over the years to extend maximum life-span in laboratory animals, their mechanism of action is still unknown. In this report, Drosophila melanogaster were maintained on caloric restricted and normal diets for varying periods, mitochondrial phospholipid fatty acids were extracted and analyzed. Whilst 10 days and 20 days of caloric restriction did not cause any significant change in mitochondrial phospholipid fatty acid composition, 30 days of caloric restriction resulted in significant increase in the major polyunsaturated fatty acid (18:2(n-6)), which subsequently led to significant increase in total unsaturated index (UI) and peroxidizability index (PI) in caloric restricted flies compared to control. The results of the study therefore, show that food restriction does not lower the rate of ageing by decreasing the level of unsaturation of mitochondrial phospholipid fatty acids. Journal of the Ghana Science Association Vol. 10 (2) 2008: pp. 62-69

Dietary fatty acid composition changes mitochondrial phospholipids and oxidative capacities in rainbow trout red muscle

Dietary conditioning of juvenile trout changed the acyl chain composition of mitochondrial phospholipids and the oxidative capacities of muscle mitochondria. Trout were fed three diets differing only in fatty acid (FA) composition. The highly unsaturated 22:6 n-3 (DHA) accounted for 0.4, 14, and 30% of fatty acids in Diets 1, 2 and 3. After 10 weeks of growth, the dietary groups differed markedly in FA composition of mitochondrial phospholipids, with significant dietary effects for virtually all FA. Mean mitochondrial DHA levels were 19, 40 and 33% in trout fed Diets 1, 2 and 3. Mitochondrial oxidative capacities changed with diet, while mitochondrial concentrations of cytochromes and of the adenylate nucleotide translocase (nmol mg(1) protein) did not. Mitochondria from fish fed Diet 1 had higher non-phosphorylating (state 4) rates at 5 degrees C than those fed other diets. When phosphorylating (state 3) rates differed between dietary groups, rates at 5 and 15 degrees C were higher for fish fed the more unsaturated diets. Stepwise multiple regressions indicated that FA composition could explain much (42-70%) of the variability of state 4 rates, particularly at 5 degrees C. At 15 degrees C, FA composition explained 16-42% of the variability of states 3 and 4 rates. Similar conclusions were obtained for the complete data set (trout fed diets 1, 2 and 3) and for the data from trout achieving similar growth rates (e.g. those fed Diets 1 and 2). Neither general characteristics of membrane FA, such as % saturates, unsaturation index, n-3, n-6 or n-3/n-6 nor levels of abundant unsaturated FA such as DHA or 18:1(n-9 + n-7), were systematically correlated with mitochondrial capacities even though they differed considerably between trout fed the different diets. Relatively minor FA (20:5n-3, 20:0, 18:2n-6, 18:3n-3, 18:0 and 15:0) showed better correlations with mitochondrial oxidative capacities. This supports the concept that acyl chain composition modulates mitochondrial capacities via interactions between membrane proteins and specific FA of particular phospholipid classes in their microenvironment.

Mitochondrial phospholipid composition and microviscosity in myocardial ischaemia

Normothermic ischaemic arrest of the isolated perfused rat heart causes profound changes in mitochondrial ultrastructure. Since the mitochondrial membranes contain a high percentage of phospholipids, an evaluation of the effect of different periods of ischaemia on mitochondrial phospholipid content and fatty acid composition was made. The results showed that ischaemia had no effect on the content of the different phospholipid classes and no correlation was observed between ultrastructural changes and mitochondrial phospholipid content. However, the phospholipid fatty acid composition of several phospholipids showed marked changes. For example, with lysophosphatidylcholine a progressive increase in the percentage saturated fatty acids was observed with increasing periods of ischaemia, while a reduction occurred in lysophosphatidylethanolamine. To determine whether the ischaemia-induced changes in mitochondrial phospholipid fatty acid composition had an effect on the physical properties of the membrane, the microviscosity of mitochondrial preparations was studied, using the lipophilic probe, 1,6-diphenyl-1,3,5-hexatrine. Mitochondria isolated from ischaemic hearts showed a progressive increase in fluorescence polarization with longer periods of ischaemia, indicating an overall increase in microviscosity. This phenomenon may be responsible for the increased mitochondrial fragility which is characteristic of ischaemic damage.