Age-related changes in mitochondrial membrane composition of rainbow trout (Oncorhynchus mykiss) heart and brain

Membrane composition, particularly of mitochondria, could be a critical factor by determining the propagation of reactions involved in mitochondrial function during periods of high oxidative stress such as rapid growth and aging. Considering that phospholipids not only contribute to the structural and physical properties of biological membranes, but also participate actively in cell signaling and apoptosis, changes affecting either class or fatty acid compositions could affect phospholipid properties and, thus, alter mitochondrial function and cell viability. In the present study, heart and brain mitochondrial membrane phospholipid compositions were analyzed in rainbow trout during the four first years of life, a period characterized by rapid growth and a sustained high metabolic rate. Specifically, farmed fish of three ages (1-, 2- and 4-years) were studied, and phospholipid class compositions of heart and brain mitochondria, and fatty acid compositions of individual phospholipid classes were determined. Rainbow trout heart and brain mitochondria showed different phospholipid compositions (class and fatty acid), likely related to tissue-specific functions. Furthermore, changes in phospholipid class and fatty acid compositions with age were also tissue-dependent. Heart mitochondria had lower proportions of cardiolipin (CL), phosphatidylserine (PS) and phosphatidylinositol, and higher levels of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) with age. Heart mitochondrial membranes became more unsaturated with age, with a significative increase of peroxidation index in CL, PS and sphingomyelin (SM). Therefore, heart mitochondria became more susceptible to oxidative damage with age. In contrast, brain mitochondrial PC and PS content decreased in 4-year-old animals while there was an increase in the proportion of SM. The three main phospholipid classes in brain (PC, PE and PS) showed decreased n- 3 polyunsaturated fatty acids, docosahexaenoic acid and peroxidation index, which indicate a different response of brain mitochondrial lipids to rapid growth and maturation

Changes in tissue and mitochondrial membrane composition during rapid growth, maturation and aging in rainbow trout, Oncorhynchus mykiss

Membrane compositions, particularly of mitochondria, could be critical factors in the mechanisms of growth and aging processes, especially during phases of high oxidative stress that result in molecular damage. In the present study, liver and mitochondrial membrane phospholipid (PL) compositions were analyzed in rainbow trout during its four first years of life, a period characterized by rapid growth and high oxidative stress. Specifically, farmed fish of three ages (1-, 2- and 4-years) were studied, and PL compositions of whole liver and liver mitochondria, and fatty acid compositions of individual PL classes were determined. Liver mitochondrial membranes showed a PL composition different to that of the whole tissue suggesting adaptation of cell and subcellular membranes to specific functions. Individual PL had characteristic fatty acid compositions that were similar in whole liver and mitochondrial membranes. Whole liver and mitochondria showed increased lipid peroxidation with age along with changes in membrane PL fatty acid compositions. Most PL classes showed similar changes in fatty acid composition among the age groups, with reduced proportions of docosahexaenoic acid (DHA) and, generally, concomitantly increased levels of monounsaturated fatty acids, which together resulted in reduced peroxidation index (PIn). However, total polyunsaturated fatty acid (PUFA) content did not change significantly with age due to increased eicosapentaenoic acid, docosapentaenoic acid and, in most PL, increased n−6 PUFA. These results suggest there may be oxidation of PL DHA with compensatory mechanisms to maintain membrane fluidity and function. However, modification of fatty acid composition of specific PLs, such as cardiolipin, could affect the electron transport chain efficiency and propagate the oxidative reaction throughout the cell. In addition, both the content and fatty acid composition of sphingomyelin, which has been suggested as a possible mediator of cell dysfunction and apoptosis, changed with age differently to the other PL classes. Moreover, these changes showed different trends between mitochondria and whole liver. These data suggest there is marked oxidative stress associated with rapid growth and maturation in rainbow trout. Changes observed in membrane lipids point to their possible participation in the processes involved in this species response to oxidative stress and damage accumulation rate

Caracterización del potencial metabólico y regulador de la ingesta del Sardo Picudo (Diplodus puntazzo)

El sargo picudo es capaz de componer, seleccionando entre preparaciones encapsuladas de macronutrientes puros, una dieta completa que se ajusta a sus necesidades fisiológicas, aún en ausencia de la información orosensorial del alimento. La técnica de encapsulación ha permitido comprobar este último extremo, resaltando la complejidad de los mecanismos implicados en la regulación de la ingesta en peces. El perfil omnívoro de la especie está caracterizado por una menor dependencia de la proteína de origen animal y una mayor aceptación de la proteína vegetal, así como por una alta capacidad para la utilización de los carbohidratos de la dieta. El sargo picudo manifiesta una gran capacidad para mantener sus funciones en presencia de bajas concentraciones de HUFA en la dieta, recurriendo en tales casos, no a un aumento de las actividades de desaturación/elongación de ácidos grasos, sino a una alta bioconservación de los HUFA en detrimento de los PUFA C18. Abstract Sharpsnout seabream are capable, selecting among encapsulated preparations manufactured with pure macronutrient, to compound a complete diet that matches their physiological needs in spite the absence of orosensory information from diet. The encapsulation technique has revealed this last point, highlighting the complexity of the mechanisms involved in the food intake regulation in fish. The omnivorous pattern of this species is characterized by a less dependence of animal protein and a greater acceptance of vegetable protein so as, a high capacity for the utilization of dietary carbohydrates. Sharpsnout seabream show a high ability to maintain their functions with low concentrations of HUFA in the diet, using in such cases, not an increase in the activities of fatty acid desaturation/elongation, but high bioconservation of HUFA in detriment of C18 PUFA

Membrane peroxidation index and maximum lifespan are negatively correlated in fish of genus Nothobranchius

Lipid composition of cell membranes is linked to metabolic rate and lifespan in mammals and birds but very little information is available for fishes. In this study, three fish species of the short-lived annual genus Nothobranchius with different maximum lifespan potentials (MLSP) and the longer-lived outgroup species Aphyosemion australe were studied to test whether they conform to the predictions of the longevity-homeoviscous adaptation (LHA) theory of aging. Lipid analyses were performed in whole fish samples and peroxidation indexes (PIn) for every PL class and for the whole membrane, were calculated. Total PL content was significantly lower in A. australe and N. korthausae, the two species with the highest MLSP, and a negative correlation between membrane total PIn and fish MLSP was found, this meaning that the longer-lived fish species have more saturated membranes and therefore, a lower susceptibility to oxidative damage, as the LHA theory posit

Macronutrient selection through post-ingestive signals in sharpsnout seabream fed on gelatine capsules and challenged with protein dilution

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Analysis of the coding sequences of clownfish reveals molecular convergence in the evolution of lifespan

Abstract Background Standard evolutionary theories of aging postulate that reduced extrinsic mortality leads to evolution of longevity. Clownfishes of the genus Amphiprion live in a symbiotic relationship with sea anemones that provide protection from predators. We performed a survey and identified at least two species with a lifespan of over 20 years. Given their small size and ease of captive reproduction, clownfish lend themselves as experimental models of exceptional longevity. To identify genetic correlates of exceptional longevity, we sequenced the transcriptomes of Amphiprion percula and A. clarkii and performed a scan for positively-selected genes (PSGs). Results The PSGs that we identified in the last common clownfish ancestor were compared with PSGs detected in long-lived mole rats and short-lived killifishes revealing convergent evolution in processes such as mitochondrial biogenesis. Among individual genes, the Mitochondrial Transcription Termination Factor 1 (MTERF1), was positively-selected in all three clades, whereas the Glutathione S-Transferase Kappa 1 (GSTK1) was under positive selection in two independent clades. For the latter, homology modelling strongly suggested that positive selection targeted enzymatically important residues. Conclusions These results indicate that specific pathways were recruited in independent lineages evolving an exceptionally extended or shortened lifespan and point to mito-nuclear balance as a key factor