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

Circadian activity rhythms during the last days of <i>Nothobranchius rachovii</i>’s life: A descriptive model of circadian system breakdown

<div><p>Several studies have been performed to identify age-related changes in the circadian system (CS) but the impairment of the CS and its chronodisruption at the end of an organism life have not been studied in depth. Aging commonly affects the input pathways into the biological clock or restraints their processing, therefore simplifying the system output, the overt rhythms. The purpose of this work was to do a complete characterization of changes that occurs in the CS in the last stage of a vertebrate organism life and to develop tools able to detect in which moment of the last days of life is the animal, using an overt rhythm, the rest-activity rhythm (RAR). For that, a fish species proposed as model for aging studies, <i>Nothobranchius rachovii</i>, has been used. A progressive and sequential CS breakdown has been described for the last 22 d of life of <i>N. rachovii</i> (∼7% of total life), suffering a general RAR impairment mainly reflected by changes in phase regularity, complexity, amplitude and the ability to stay synchronized to the LD cycle. Also, an equation of days remaining of life, based on the RAR description, has been calculated and proposed as a tool to identify close-to-death individuals which could be subjected to an adequate restoring treatment to enhance the CS function and improve their well-being.</p></div

Age-related changes in mitochondrial membrane composition of Nothobranchius furzeri. Comparison with a longer-living Nothobranchius species

Membrane compositions, particularly of mitochondria, could be critical factors in the mechanisms of growth and aging, especially during phases of high oxidative stress that result in molecular damage. Changes affecting lipid class or fatty acid (FA) compositions could affect phospholipid (PL) properties and alter mitochondrial function. In the present study, mitochondrial membrane PL compositions were analysed throughout the life-cycle of Nothobranchius furzeri, a species with explosive growth and one of the shortest-lived vertebrates. Mitochondrial PLs showed several changes with age. Proportions of total PLs and PC were reduced while an increase in PS, CL and PE was observed, mainly between the 2.5 and 5 months of fish age, the time during which animals doubled their weight. FA compositions of individual PLs in mitochondria were also significantly affected with age suggesting the existence of increasing damage to mitochondrial lipids during the life- cycle of N. furzeri that could be one of the main contributors to degraded mitochondrial function associated with aging. The peroxidation index values from N. furzeri mitochondrial PLs were significantly lower than those reported in N. rachovii, a species with a 2-fold longer life span than N. furzeri, which seems to contradict the membrane pacemaker theory of animal metabolis