Natural dietary shifts offer the opportunity to address the nutritional physiological characters required to thrive on a particular diet. Here, we studied the nutritional physiology of Podarcis siculus , populations of which on Pod Mrčaru, Croatia, have become omnivorous and morphologically distinct (including the development of valves in the hindgut) from their insectivorous source population on Pod Kopište. We compared gut structure and function between the two island populations of this lizard species and contrasted them with an insectivorous mainland outgroup population in Zagreb. Based on the Adaptive Modulation Hypothesis, we predicted changes in gut size and structure, digestive enzyme activities, microbial fermentation products (SCFAs), and plant material digestibility concomitant with this dietary change. The Pod Mrčaru population had heavier guts than the mainland population, but no other differences in gut structure. Most of the enzymatic differences we detected were between the island populations and the outgroup population. The Pod Mrčaru lizards had higher amylase and trehalase activities in their hindguts compared to the Pod Kopište population, the Pod Kopište lizards had greater SCFA concentrations in their hindguts than the plant-eating Pod Mrčaru population. Interestingly, the differences between the Pod Mrčaru and Pod Kopište populations are primarily localized to the hindgut and are likely influenced by microbial communities and a higher food intake by the Pod Mrčaru lizards. Although subtle, the changes in hindgut digestive physiology impact digestibility of plant material-Pod Mrčaru lizards had higher digestibility of herbivorous and omnivorous diets in the laboratory than did their source population.
La aplicación de elicitores induce una respuesta en el nivel de metabolitos secundarios y en la metilación del ADN de las plantas. Este trabajo tuvo como objetivo aplicar dos elicitores a plantas de estevia y evaluar el contenido de varios compuestos fenólicos y glucosidos de esteviol; así como, el nivel de metilación en plantas elicitada y no elicitada. Los fenólicos y glucosidos fueron determinados por HPLC y espectrofotométria mientras que la metilación por 5-mC DNA ELISA. Como resultado de la elicitación, se observó un ligero incremento de los ácidos clorogénico y ferulico. Los fenoles totales se incrementaron a los siete días después de la aplicación de los elicitores, sin mostrar ningún incremento a los 15 y 21 días. Por el contrario, los flavonoides y los taninos aumentaron significativamente a los 7, 15 y 21 días de la aplicación. El contenido del esteviosido y los rebaudiosidos A y C aumentaron 9.5, 5.3 y 3.3 veces más que el grupo control. A lo largo del experimento, el rebaudiosido C fue mayor en su concentración que la suma del esteviol y del rebaudiosido A. Se observó que las plantas elicitadas presentaron un nivel de metillación menor que las no elicitadas Por su alto contenido de rebaudiosido C, la estevia criollo, aquí utilizada, puede producir un edulcorante menos amargo que otros materiales. La elicitacion de estevia puede ser una estrategia para incrementar el rendimiento de edulcorantes.
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