Rheological Behaviour of an Insoluble Lemon Fibre as Affected by Stirring, Temperature, Time and Storage

The final publication is available at link.springer.comIn this work, the effect the preparation method (two different stirring systems at two temperatures and times), fibre concentration (between 2% and 3%), temperature (between 10 °C and 50 °C) and storage time (between 24 h and 50 days at 5 °C) had on the flow properties of a suspension of dietary lemon fibre prepared with a 45° Brix sucrose solution were evaluated. This information will be helpful in order to discover the best possibilities of using fibre to increase the viscosity of certain kinds of products, depending on the processing, storage and consumption conditions. The obtained results indicate that all the aspects which contribute to increase component solubilisation and the interaction of the insoluble fraction with the aqueous phase when preparing the suspension, such as a decrease in particle size, a rise in temperature or a longer homogenization time, entail a higher apparent viscosity. Moreover, favoring the solubilisation in the preparation process leads to a more stable rheological behaviour of the suspension during storage. As expected, the apparent viscosity of suspensions was dependent on the shear rate, concentration and temperature. A thixotropic behaviour of fibre suspension was only observed at a very low shear rate (5 s -1). © 2010 Springer Science + Business Media, LLC.Córdoba Sequeira, A.; Camacho Vidal, MM.; Martínez Navarrete, N. (2012). Rheological Behaviour of an Insoluble Lemon Fibre as Affected by Stirring, Temperature, Time and Storage. Food and Bioprocess Technology. 5(3):1083-1092. doi:10.1007/s11947-010-0478-2S1083109253Akdogan, H., & McHugh, T.-H. (2000). Flow characterization of peach products during extrusion. Food Engineering and Physical Properties, 65(3), 471–475.Alonso, M.-L., Larrodé, O., & Zapico, J. (1995). Rheological behaviour of infant foods. Journal of Texture Studies, 26, 193–202.Duran, L., & Costell, E. (1982). 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Trophic ecology of the chiton Acanthopleura echinata on Chilean rocky shores Ecología trófica del chitón Acanthopleura echinata en costas rocosas de Chile

Polyplacophorans are common herbivores on rocky shores, but basic aspects of their ecology remain scarcely studied and their role within communities could be more complex than previously considered. Such is the case of Acanthopleura echinata (Barnes), one of the largest and most conspicuous chitons in the world, and at the same time, one of the least known intertidal species in the southeastern Pacific. To improve the basic ecological knowledge of this potentially important intertidal consumer, we studied the diet of A. echinata and its variation among sites of varying levels of coastal upwelling spread over 1000 km along the coast of northern Chile. A seasonal evaluation of diet, body size distribution and density at sites expected to vary in overall nutrient loadings, benthic algal productivity and sea surface temperature, allowed us to examine plasticity in Acantholeura diet and body size. Overall, A. echinata consumed 85 items of algae (64.7 %, mainly fleshy and calcified encrusting thalli) and invertebrates (35.3 %, mainly barnacles). Diet was always dominated by encrusting corallines, although the proportion of algae increased with body size suggesting an ontogenetic variation in feeding habits. Although the number and occurrence frequency of dietary items varied significantly in time and space, there were no consistent seasonal patterns and the dominant items in the diet remained the same at all places. The density of A. echinata showed no significant spatial variation, but its body size and diet breadth correlated positively among sites and both tended to increase with latitude. Our results show that A. echinata is a generalist, polyphagous consumer with a high potential for affecting the space-occupancy dynamics in the intertidal system, and also that among site variation in diet bears no simple relationship with variation in sea surface temperature and upwelling intensity.<br>Los poliplacóforos son herbívoros comunes en costas rocosas, pero los aspectos básicos de su ecología han sido escasamente estudiados y su rol trófico dentro de las comunidades podría ser más complejo de lo considerado hasta ahora. Tal es el caso de Acanthopleura echinata (Barnes), uno de los chitones más grandes y conspicuos en el mundo, pero a la vez una de las especies intermareales menos conocidas del Pacífico sudeste. A fin de mejorar el conocimiento ecológico básico de este consumidor intermareal potencialmente importante, estudiamos la dieta de A. echinata y su variación entre sitios con distintos niveles de surgencia costera distribuidos a través de 1000 km en la costa del norte de Chile. Una evaluación estacional de la dieta, distribución de tamaño corporal y densidad en sitios con diferencias esperables en aporte total de nutrientes, productividad de algas bentónicas y temperatura superficial del mar, permitió examinar la plasticidad de la dieta y el tamaño corporal de Acanthopleura. Globalmente, A. echinata consumió 85 ítemes de algas (64.7 %, principalmente algas incrustantes calcificadas y blandas) e invertebrados (35.3 %, principalmente cirripedios). Su dieta estuvo siempre dominada por coralinas incrustantes, aunque la proporción de algas aumentó con el tamaño corporal sugiriendo una variación ontogenética en sus hábitos tróficos. Aunque el número y frecuencia de ocurrencia de ítemes dietarios variaron significativamente en tiempo y espacio, no hubo patrones estacionales consistentes y los ítemes dominantes en la dieta fueron los mismos en todos los lugares. La densidad de A. echinata no varió significativamente a través del espacio, pero su tamaño corporal y su amplitud dietaria se correlacionaron positivamente entre sitios y ambos tendieron a aumentar con la latitud. Nuestros resultados muestran que A. echinata es un consumidor generalista y polífago con alto potencial para afectar la dinámica de ocupación del espacio en el sistema intermareal, y además que la variación dietaria entre sitios no tiene una relación evidente con la variación en intensidad de surgencia y temperatura superficial del mar

Caracterización trófica del placóforo intermareal Enoplochiton niger en el norte de Chile: variación ambiental y patrones dietarios a nivel local y region Trophic characterization of the intertidal placophoran Enoplochiton niger in northern Chile: environmental variation and dietary patterns at local and regional levels

El rol e impacto de los herbívoros en la trama trófica de comunidades intermareales rocosas podría ser más diverso y complejo de lo considerado hasta ahora, particularmente en el caso de consumidores de mayor tamaño y abundancia como el molusco placóforo Enoplochiton niger. Esta especie es uno de los pastoreadores de mayor tamaño (hasta 20 cm) e importancia ecológica en las costas rocosas del norte de Chile, pero también una de las especies menos conocidas en términos tróficos. Este trabajo presenta una evaluación de los patrones dietarios de E. niger en cuatro comunidades del norte de Chile, distribuidas en 1.000 km de costa y muestreadas estacionalmente entre invierno 2004 y otoño 2006. Además se analizó la relación de su dieta con factores biológicos y físicos, incluyendo el efecto potencial del evento El Niño 2004-2005 ocurrido durante el período de estudio. A nivel regional, el espectro dietario de E. niger abarcó un total de 98 recursos (60 ítemes algales y 38 ítemes invertebrados), y los ítemes más importantes fueron organismos sésiles con formas de crecimiento incrustante o en capa. E. niger mostró una gran amplitud de nicho tanto a nivel regional como local (rango: 20,7-28,0; índice de Levins), con una riqueza dietaria a nivel individual independiente del tamaño corporal. Tanto el número de ítemes dietarios consumidos por individuo como la composición taxonómica de la dieta no mostraron diferencias significativas entre comunidades, pero variaron significativamente entre el período asociado al evento El Niño y el período posterior. No hubo ninguna relación clara entre los patrones dietarios de E. niger y los niveles contrastantes de intensidad de surgencia entre las comunidades estudiadas. Los resultados muestran que E. niger es un consumidor generalista y polífago, y un potencial omnívoro, el cual podría tener un alto impacto sobre los patrones de ocupación de espacio en la comunidad intermareal.<br>The role and impact of herbivores on rocky intertidal food webs could be more complex and diverse than previously considered, particularly in the case of larger and more abundant consumers such as the placophoran mollusc Enoplochiton niger. This species is one of the largest (up to 20 cm) and ecologically most important grazers on rocky shores of northern Chile, but also one of the lesser known species in trophic terms. This work presents an assessment of the dietary patterns of E. niger in four communities of northern Chile, distributed along 1,000 km of coastline and sampled seasonally from winter 2004 to autumn 2006. The analysis included the relationship of its diet with physical and biological factors, and particularly the potential effect of the 2004-2005 El Niño event that occurred during the study period. At a regional level, the dietary spectrum of E. niger comprised a total of 98 food resources (60 algal Ítems and 38 invertebrate Ítems), and the most important Ítems were sessile organisms of encrusting and layer-forming growth habits. E. niger exhibited a very high niche breadth at both local and regional levels (ranging from 20.7 to 28.0; Levins' index), and its dietary richness at the individual level was independent from its body size. Both the number of dietary ítems consumed per individual and the taxonomic composition of the diet did not show statistical differences among communities, but they were significantly different between the El Niño and non-El Niño periods. There was no clear relationship between the dietary patterns of E. niger and the contrasting levels of upwelling intensity among the communities studied. The results show that E. niger is a generalist polyphagous consumer, and a potential omnivore, which could have a high level of impact on space occupancy patterns in the intertidal community

Latitudinal distribution of polyplacophorans along the South-eastern Pacific coast: unravelling biases in geographical diversity patterns

Latitudinal diversity patterns in marine species are commonly estimated from literature records, which at times are incomplete and/or biased. Advances in molecular phylogenetics have contributed to avoid this bias, clarifying the identity of the species, improving our knowledge of species diversity and distribution. With the aim to identify biogeographic biases, we compiled and compared range distribution data of polyplacophorans along the South-eastern Pacific (SEP) coast (0 degrees-56 degrees S) generated from: (i) literature review (LIT dataset) and (ii) Operational Taxonomic Units (OTUs dataset), based on the analysis of 8949 individuals obtained from field sampling and biological collections. Cytochrome oxidase I (COI) and 16S rRNA of 104 specimens were used for genetic identification of conflictive morphospecies. Multivariate analysis (nMDS, PERMANOVA) were applied to test differences between datasets (LIT, OTUs) and also between biogeographic ecoregions. Just like prior studies based on literature reviews, the richness of LIT species showed an increase with latitude. Contrastingly, OTUs' richness peaked at intermediate latitudes showing a bell-shaped distribution, indicating that the LIT dataset was flawed by inaccuracies in the identification and location of polyplacophoran species on the South-eastern Pacific, causing an overestimation of their geographic ranges. Our results contrast with the previous richness patterns described for the SEP polyplacophorans, where species richness was reported to increase with latitude. Both an overestimation of geographic ranges and inaccuracies in the identification of species cause these differences. Biogeographical studies should be conducted on the basis of a comprehensive review of specimens with verifiable occurrences, and incorporate as far as possible genetic analysis to define the identity of conflicting morphospecies, in order to improve the estimation of species richness and the understanding of marine biodiversity.Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) CONICYT FONDECYT 1130266 3140610 1040425 National Science Foundation (NSF) DEB-135523

Nigral-specific increase in ser31 phosphorylation compensates for tyrosine hydroxylase protein and nigrostriatal neuron loss: Implications for delaying parkinsonian signs

Compensatory mechanisms that augment dopamine (DA) signaling are thought to mitigate onset of hypokinesia prior to major loss of tyrosine hydroxylase (TH) in striatum that occurs in Parkinson\u27s disease. However, the identity of such mechanisms remains elusive. In the present study, the rat nigrostriatal pathway was unilaterally-lesioned with 6-hydroxydopamine (6-OHDA) to determine whether differences in DA content, TH protein, TH phosphorylation, or D receptor expression in striatum or substantia nigra (SN) aligned with hypokinesia onset and severity at two time points. In striatum, DA and TH loss reached its maximum (\u3e90%) 7 days after lesion induction. However, in SN, no DA loss occurred, despite ∼60% TH loss. Hypokinesia was established at 21 days post-lesion and maintained at 28 days. At this time, DA loss was ∼60% in the SN, but still of lesser magnitude than TH loss. At day 7 and 28, ser31 TH phosphorylation increased only in SN, corresponding to less DA versus TH protein loss. In contrast, ser40 TH phosphorylation was unaffected in either region. Despite DA loss in both regions at day 28, D receptor expression increased only in lesioned SN. These results support the concept that augmented components of DA signaling in the SN, through increased ser31 TH phosphorylation and D receptor expression, contribute as compensatory mechanisms against progressive nigrostriatal neuron and TH protein loss, and may mitigate hypokinesia severity