Dinámica de la variación de las especies en declive: Variación neutral y funcional en el lince ibérico

Programa de Doctorado en Medio Ambiente y SociedadLínea de Investigación: Biodiversidad y Biología de la ConservaciónClave Programa: DAMCódigo Línea: 83El declive y fragmentación de las poblaciones implica un aumento de la deriva genética que puede resultar en pérdidas de diversidad genética y acumulación de consanguinidad. Las disminuciones del potencial adaptativo y de eficacia biológica que éstos procesos pueden llevar asociados se reconocen como riesgos para la persistencia de las especies. Las pérdidas de diversidad se han documentado en la gran mayoría de los casos a través de marcadores moleculares supuestamente neutrales, quedando la duda de hasta que punto éstos representan la variación adaptativa, por los posibles efectos de la selección sobre ésta. Una parte muy importante de la variación claramente adaptativa, que puede ser especialmente relevante para contrarrestar los riesgos de extinción derivados de enfermedades, es la relacionada con la respuesta inmune. La capacidad de respuesta inmune está condicionada en buena medida a la variación presente en genes claves para el reconocimiento y presentación de antígenos. Entre éstos, los genes clase I y clase II del Complejo Mayor de Histocompatibilidad (MHC) son los más estudiados, pero no los únicos elementos importantes. El lince ibérico (Lynx pardinus) ha sufrido un declive y una fragmentación muy acusadas en las últimas décadas que le ha colocado al borde de la extinción y le ha llevado a ser una de las especies con diversidad genética más baja. En cambio, hemos podido constatar que la selección balanceadora ha sido capaz de contrarrestar, al menos para estos genes de inmunidad, el devastador efecto que la deriva genetica que ha tenido para la especie a nivel neutral.Universidad Pablo de Olavide de Sevilla. Departamento de Biología Molecular e Ingeniería BioquímicaPostprin

Método rápido para la determinación de compuestos polares en aceites y grasas de fritura

The determination of polar compounds by adsorption chromatography is the most accepted method for the analysis of used frying fats due to its high precision and accuracy. However, this method is expensive and time consuming. In this study, a rapid analytical method to determine polar compounds is proposed. Starting from milligrams of sample dissolved in a solution of hexane containing methyl oleate as internal standard, the nonpolar fraction, which comprises the non-altered triglycerides (TG) and the internal standard, is obtained by solid phase extraction. Then, the non polar fraction is quantitatively analyzed in 15 min by high-performance size-exclusion chromatography (HPSEC) and the polar fraction is determined by difference of weight. Response factors for pure TG and FAME were calculated. Six samples of sunflower oils of different degrees of unsaturation were analyzed in triplicate and the results were compared with those obtained by the gravimetric method based on silica classical column chromatography. Results showed no significant differences between the two methods. In addition, the repeatability of the proposed method was excellent, as the coefficient of variation ranged from 1.5 to 13% depending on the contents of polar compounds.La determinación de compuestos polares mediante cromatografía de adsorción es el método más aceptado en el análisis de aceites y grasas de fritura debido a su elevada exactitud y precisión. Sin embargo, la determinación es costosa, debido al elevado consumo de sílice y disolventes, y son necesarias varias horas para la obtención del resultado. En este estudio se propone una determinación alternativa rápida. Partiendo de miligramos de muestra disueltos en una solución de hexano con oleato de metilo como patrón interno, la fracción no polar, que contiene los triglicéridos no alterados y el patrón interno, es aislada mediante extracción en fase sólida. Posteriormente, la fracción no polar se analiza cuantitativamente en 15 min mediante cromatografía líquida de exclusión y la cantidad de fracción polar se determina por diferencia de peso. Se han calculado los factores de respuesta de triglicéridos y ésteres metílicos. El método se ha aplicado a seis muestras de aceites de girasol de distinto grado de insaturación evaluadas por triplicado y los resultados se han comparado con los obtenidos mediante la determinación gravimétrica basada en cromatografía en columna clásica de sílice. No se han encontrado diferencias significativas entre los dos grupos de resultados. Por otra parte, la repetibilidad fue excelente ya que los coeficientes de variación oscilaron entre 1.5 y 13% dependiendo del contenido en compuestos polares de los aceites.This research work was supported by Junta de Andalucía and Ministerio de Educación y Ciencia (Project AGL 2004-00148).Peer reviewe

Análisis de aceites y grasas de fritura para producción de biodiesel

6 pages, 2 tables, 3 figures.[EN] Used frying fats and oils with highly variable and uncontrolled quality are used for the production of biodiesel. The objective of this study was to define the analytical methods useful to obtaining information on the quality of the used frying oils as raw material for biodiesels as well as for the characterization of the biodiesels obtained from them. Twentyfour used frying oils from restaurants and domestic fryers were analyzed before and after transesterification to fatty acid methyl esters (FAME). From a detailed analysis of the samples by means of a combination of adsorption and size exclusion chromatography, the quantitative importance of polymeric compounds was deduced both from the direct analysis of the oils and from their FAME. Excellent linear correlation between polar compounds and polar FAME (R 0.9768) was found. The possibilities of interferences from polar fatty acid in the standard method to determine the ester content are defined. Finally, determination of non-polar FAME by silica column is proposed as a good alternative to the gas chromatography method.[ES] Los aceites y grasas de fritura, que se caracterizan por tener una calidad muy variable, se utilizan como material prima para la producción de biodiesel. El objetivo de este estudio es definir la utilidad de los métodos analíticos desarrollados para los aceites y grasas de fritura para caracterizar el biodiesel obtenido. Veinticuatro aceites de fritura procedentes del sector de restauración y de fritura doméstica fueron analizados antes y después de su transesterificación a ésteres metílicos de ácidos grasos. A partir de un análisis detallado mediante cromatografías de adsorción y exclusión, se deduce la importancia cuantitativa de los compuestos de polimerización tanto en el análisis directo de los aceites como en el análisis de los ésteres metílicos. Se encontró una excelente correlación lineal entre los compuestos polares y los ésteres metílicos polares (R=0.9768). Se definen las interferencias de los compuestos formados durante la fritura en el análisis estándar para conocer la calidad del biodiesel y se propone la determinación de ésteres metílicos no polares como una buena alternativa a la determinación cromatográfica estándar.This research work was supported by Junta de Andalucía and MCYT (Project AGL 2004-00148).Peer reviewe

New Analytical Evidence of Discontinuous Oxidation in Dried Microencapsulated Lipids

24 Páginas; 4 FigurasFormation of hydroperoxy-, keto- and hydroxy-dienes was studied at 40 °C in fatty acid methyl esters (FAME) microencapsulated in a dairy-like matrix formed by lactose and sodium caseinate. The FAME were obtained from conventional sunflower oil and the microcapsules were prepared by freeze-drying of an oil-in-water emulsion. For comparative purposes a neat sample of FAME was also tested. Results showed that for a given content of hydroperoxydienes much more elevated amounts of secondary products were detected in the microencapsulated sample compared to the neat sample of FAME. The contents of keto- and hydroxy-dienes found in the microencapsulated FAME ranged as a whole between 6 and 31 wt% of the analyzed compounds, while the neat sample showed values lower than 1.5 %. Along with the fact that relatively higher contents of polymers were also found in the encapsulated sample, these results can be attributed to lipid droplets with very different oxidation states. On the one hand, the extract would be formed from droplets in early stages of oxidation containing hydroperoxides and very low contents of secondary products and, on the other, from droplets in advanced stages with decreased hydroperoxides and substantial contents of secondary products. Unlike the neat sample, hydroxy-dienes formed with significantly higher amounts than keto-dienes in the microencapsulated FAME, suggesting a possible chemical role of the encapsulation matrix.This work was funded by the “Ministerio de Economía y Competitividad” through project AGL2013-45110-R, “Junta de Andalucía” through project P09-AGR-4622 and CSIC through a PIE project with reference 201270E134.Peer reviewe

Assessment of Discontinuous Oxidation in Microencapsulated FAME based upon Analysis of Hydroperoxy-, Keto- and Hydroperoxydienes

Today there are a number of formulated food o/w emulsions that are dehydrated such as infant formulae and others containing polyunsaturated lipids and oils of nutritional value. As a result of drying, the lipids are microencapsulated in the carbohydrates and/or proteins formerly present in the aqueous phase. Evaluation and control of lipid oxidation in such products are of great significance because of losses of quality and the formation of compounds that may even be detrimental to health. Oxidized droplets may occur in different conditions and complex mixtures of primary, secondary and even advanced oxidation compounds may be detected in quite different proportions to those found in continuous phase. In these cases evaluation of oxidation would be possible by applying a novel HPLC method. In the present study formation of hydroperoxy-, keto- and hydroxy- dienes was studied at 40 ºC in fatty acid methyl esters (FAME) microencapsulated in a dairy-like matrix. The FAME were obtained from conventional sunflower oil and the microcapsules were prepared by freeze-drying of an oil-in-water emulsion containing sodium caseinate and lactose. For comparative purposes a neat sample of FAME was also assayed. Results showed that for a given content of hydroperoxydienes much more elevated amounts of secondary products, i.e. keto- and hydroxy- dienes, were detected in the microencapsulated sample, ranging as a whole between 6 and 31 wt% of the analyzed compounds, compared to the neat sample, which showed values lower than 1.5%. Along with the fact that relatively higher contents of polymers were found in the encapsulated sample, these results can be attributed to lipid droplets with very different oxidation states. On the one hand, the extract would be formed from droplets in early stages of oxidation containing hydroperoxides and very low contents of secondary products and, on the other, from droplets in advanced stages with decreased hydroperoxides and substantial contents of secondary products. Unlike the neat sample, hydroxydienes formed at significantly higher amounts than ketodienes in the microencapsulated FAME, suggesting a possible chemical role of the encapsulation matrix.This work was funded by the Spanish Ministry of Economy and Competitiveness through project AGL2013-45110-RPeer Reviewe

Inhibition of hydroperoxy-, keto- and hydroxy-FAME by alpha- and delta-tocopherol at Rancimat conditions

The effects of alpha- and delta-tocopherol on inhibition of hydroperoxides, keto and hydroxy compounds at Rancimat conditions, i.e. 100 ºC and air bubbling, were studied in samples of fatty acid methyl esters (FAME) obtained from high linoleic (HL) and high oleic (HO) sunflower oils. Simple hydroperoxides from methyl linoleate and oleate and keto and hydroxy compounds derived from methyl linoleate hydroperoxides were analyzed by HPLC-UV-ELS. Different tocopherol concentrations, namely, 10, 50, 100, 500 and 1000 mg/kg, were tested. Irrespective of the lipid substrate and the initial concentration of tocopherol, results showed that the content of hydroperoxides accumulated during the induction period was remarkably higher in the samples containing delta-tocopherol. The relative concentrations of oleate hydroperoxides in the HO samples were also higher in the presence of delta-tocopherol. Alpha-tocopherol was more effective in inhibiting hydroperoxides at low levels, being 100 mg/kg its optimal concentration, while delta-tocopherol displayed optimal protection at 1000 mg/kg. Under the oxidation conditions applied, neither alpha- nor delta-tocopherol showed a protective effect on hydroperoxide decomposition at any level assayed. Formation of keto- and hydroxy-dienes was more related to the concentration of their hydroperoxide precursors. Furthermore, both tocopherols gave rise to increased concentrations of ketodienes at 500 and 1000 mg/kg compared to the controls. Such an effect was more pronounced for alpha-tocopherol and in the HL samples.This work was Funded by the Spanish Ministry of Economy and Competitiveness through project AGL2013-45110-R and CSIC through a PIE project with reference 201270E134. The authors also thank the Spanish Ministry of Economy and Competitiveness for supporting Susana Marmesat with a “Juan de la Cierva” contract with reference JCI-2011-08874.Peer Reviewe

Variables de difícil control en los estudios de fritura: Diferencias en repetitividad entre experimentos de termoxidación y de fritura

Palm oil, soybean oil and partially hydrogenated soybean oil were used to define the repeatability of oil degradation under thermoxidation in the absence of food and during the frying of potatoes. Total polar compounds and their constituent polymeric triglycerides, oxidized monomeric triglycerides and diglycerides were analyzed. The oils were thermoxidized under standard conditions in a Rancimat apparatus at 180 °C for 25 hours. Discontinuous frying experiments were carried out in triplicate in three apparently identical domestic fryers. Five batches of potatoes were fried per day in each fryer. Oils were heated at 180 °C in periods of 5 h per day during 5 consecutive days so that the total heating period was 25 h. Repeatability was high in the thermoxidation assays and rather low in the frying experiments. Significant differences between the oils were found in the thermoxidation experiments, while no significant differences were found in the frying assays due to large standard deviations. The participation of variables related to the fryer performance which are difficult to control, was deduced. Among them, differences in the heating/cooling cycles at high temperature might be important. The contribution of fryer performance to the decreased repeatability was confirmed in further frying experiments with palm oil. Results showed that repeatability for the same fryer was higher than that obtained when different fryers were considered.Se estudia la repetibilidad de los resultados obtenidos en el calentamiento de los aceites y grasas a temperatura elevada utilizando aceite de palma, aceite de soja y aceite de soja parcialmente hidrogenado. Partiendo de la repetibilidad de las determinaciones analíticas utilizadas para la evaluación de la degradación de los aceites y grasas a elevada temperatura, el análisis de compuestos polares y de su distribución en polímeros de triglicéridos, triglicéridos monómeros oxidados y diglicéridos, se analizan las desviaciones obtenidas durante el tratamiento termoxidativo en condiciones estándar (Rancimat a 180 °C durante 25 horas) y durante la fritura de patatas en freidoras domésticas en condiciones bien controladas. Los resultados indican la existencia de diferencias significativas en el comportamiento de los aceites en el tratamiento termoxidativo en ausencia de alimentos aunque no fue posible encontrar diferencias significativas en la fritura discontinua cuando se realizan los triplicados en distintas freidoras, debido a las elevadas desviaciones obtenidas entre ensayos. En un posterior ensayo con aceite de palma utilizando la misma freidora para los tres ensayos de frituras se obtuvieron menores desviaciones. Los resultados indican la existencia de variables de difícil control entre las que se apuntan diferencias de temperatura media debido a las diferencias en los ciclos de calentamiento/enfriamiento a temperatura elevada

Effect of temperature on the oxidation of soybean biodiesel

This paper proposes to examine the effect of temperature on the oxidation behavior of biodiesel. Soybean biodiesel was oxidized at different temperatures (room temperature, 60, and 110 °C), and the increase in primary and secondary oxidation products was determined based on the peroxide and anisidine values, respectively, during the induction period (IP). The results indicated that the evolution of hydroperoxides followed zero-order reaction kinetics during the IP at all temperatures, and their rate of formation was exponentially affected by temperature. It was also deduced that temperature influenced the ratio between primary and secondary oxidation products formation, which decreased as the temperature increased. Additionally, it was possible to predict the oxidation behavior of the soybean biodiesel at room temperature by an exponential model fitted to the IP values at different temperatures (70, 80, 90, 100, and 110 °C) using the Rancimat apparatus.The authors are grateful to the São Paulo Research Foundation (FAPESP) for their financial support and to the Coordination for the Improvement of Higher Level or Education Personnel (CAPES) for a scholarship (Process n° BEX 6667/12-0).Peer Reviewe

Evolución de la oxidación en el aceite de soja y su biodiesel en las condiciones del test de estabilidad a la oxidación

The objective of this study was to know the evolution of the oxidation of soybean oil and biodiesel under the conditions of the oxidation stability test (110 °C) using the Rancimat apparatus. Samples were analyzed at different periods of time until the end of the induction period. The analytical determinations related to the changes in oxidation include peroxide value, anisidine value, natural tocopherols and polar compounds. Acid value, kinematic viscosity, polymers and ester content were also analyzed because of their relevance in the evaluation of biodiesel quality. Results showed that only peroxide value and the group of polar compounds including hydroperoxides, i.e. oxidized monomeric TAG in the oil and oxidized monomeric FAME in the biodiesel increased significantly during the early oxidation stage. The end of the induction period was marked by a rapid increase in polymerization compounds and the exhaustion of tocopherols. Significant changes in acid value, viscosity and ester content were only observed after the end of the induction period.El objetivo de este estudio fue conocer la evolución de la oxidación del aceite de soja y de su biodiesel a 110 °C en las condiciones del método estándar para la determinación de la estabilidad oxidativa, usando el aparato Rancimat. Las muestras se analizaron en diferentes períodos de tiempo hasta que el período de inducción fue sobrepasado. Se determinaron los índices de peróxidos y anisidina, los tocoferoles y los compuestos polares cuyos cambios están relacionados con el desarrollo de la alteración oxidativa. Además, fueron determinados el índice de acidez, la viscosidad y el contenido en ésteres, de interés en el análisis de la calidad del biodiesel. Los resultados indicaron que sólo el índice de peróxidos y el grupo de compuestos polares que incluye los hidroperóxidos (triglicéridos oxidados monómeros en el aceite y ésteres metílicos oxidados monómeros en el biodiesel) aumentaron durante todo el periodo de inducción. El final del período de inducción fue determinado por el marcado aumento de los compuestos de polimerización y la pérdida total de los tocoferoles. Sólo se observaron cambios significativos en el índice de acidez, viscosidad y contenido de ésteres al final del periodo de inducción

Aplicación de la cromatografía de gases a elevada temperatura en el análisis de aceites y grasas de fritura

The determination of polar compounds is the most commonly applied technique in the analysis of used frying fats and oils. High-temperature gas chromatography allows for a quantitative determination of oxidized monomeric FAME and dimeric FAME thus giving extra information on oil degradation starting from the fraction of polar compounds. Polar compounds are transesterified and methyl esters are separated in a VF-5ht Ultimetal column (150 °C -held for 5 min- rising at 5 °C min-1 to 370 °C and held for 5 min) using methyl tricosanoate as internal standard. Results are compared with those obtained by more complex alternative methodology using high-performance size-exclusion chromatography.La determinación de compuestos polares es el método analítico más utilizado en el análisis de los aceites y grasas de fritura. En este estudio se aprovechan las posibilidades actuales de la cromatografía de gases a elevada temperatura que permite cuantificar los dos grupos mayoritarios de ácidos grasos polares como ésteres metílicos: los monómeros oxidados y los dímeros. Con tal fin, la fracción de compuestos polares se tranesterifica y los ésteres metílicos obtenidos se separan en una columna de VF-5ht Ultimetal, usando tricosanoato de metilo como estándar interno, en las siguientes condiciones: 150 °C durante 5 minutos, 5 °C/min hasta 370 °C y 5 minutos a 370 °C. Los resultados se comparan con los obtenidos mediante técnica alternativa más compleja basada en la cromatografía de exclusión por tamaño molecular