Characterization of Keratinocyte Differentiation Induced by Ascorbic Acid: Protein Kinase C Involvement and Vitamin C Homeostasis11The authors declared not to have a conflict of interest.

Epidermal keratinocytes undergo differentiation in response to several stimuli to form the cornified envelope, a structure that contributes to the barrier function of skin. Although differentiation has been extensively analyzed, the precise role of vitamin C during this process is still not defined. Ascorbic acid, besides acting as a radical scavenger, has been shown to promote mesenchymal differentiation. In this study, we found that keratinocytes grown in ascorbate-supplemented medium developed a differentiated phenotype, as demonstrated by enhanced expression of marker genes and increase in cornified envelope content. The pro-differentiating effects of ascorbate were mediated by the protein-kinase-C-dependent induction of activating protein 1 DNA binding activity; indeed, down-modulation of protein kinase C activity abolished differentiation triggered by ascorbic acid. Although vitamin C appeared to regulate the same signaling pathway modulated by calcium, a classical in vitro inducer of epidermal differentiation, nonetheless terminally differentiated keratinocytes exhibited different ascorbate homeostasis and cellular antioxidant status. Indeed, we found that, unlike calcium, differentiation promoted by ascorbate was accompanied by (i) an enhanced ascorbate transport, due to overexpression of specific transporters, (ii) a great efficiency of dehydroascorbate uptake, and (iii) an increase in glutathione content with respect to proliferating cells. Ascorbic acid may be useful to promote epidermal differentiation, avoiding depletion of hydrophilic antioxidant stores

Kinetics of Electron Transfer between Azurin and Cytochrome 551 from Pseudomonas

Abstract The kinetics of electron transfer between the copper-containing protein azurin (Cu++/Cu+) and cytochrome 551 (Fe+++/Fe++) from Pseudomonas has been studied by rapid mixing methods. The reaction in both directions is fast; at low reagent concentrations (∼10-6 m) the apparent second order rate constant, at 20°, is about 3 x 106 m-1 sec-1 for the reaction Fe++ + Cu++ and 1.4 x 106 m-1 sec-1 for the reaction Fe+++ + Cu+. At high reagent concentrations the rates tend to reach a limiting value indicating that the reaction is not a simple second order process. The kinetics of the reactions of the reduced and oxidized forms of azurin and Pseudomonas cytochrome 551 with ferricyanide and dithionite has also been investigated. The rates of these reactions, at comparable reagent concentrations, are orders of magnitude lower than that between azurin and cytochrome 551

Otoliths as indicators for fish behaviour and procurement strategies of hunter-gatherers in north Patagonia

This study evaluates the potential use of archaeological otoliths of Genidens barbus (Cuvier and Valenciennes) as a tool to study fish behavior and hunter-gatherers procurement strategies on the North Patagonian coast. The studied samples come from the San Antonio archaeological locality dated at ca. 1000-800 14C yr BP (Late Holocene). To assess whether exposure to fire significantly affects the otolith Sr:Ca and Ba:Ca ratios, burned and unburned modern lapilli otoliths have been analyzed by Laser Ablation Inductively Coupled Plasma Mass Spectrometry and no statistically significant differences were found between the results of both treatments. Core-toedge chemical time series were carried out on ancient otoliths (ca. 1000 14C yr BP) in order to study the fish life history. Three amphidromous patterns were found for ancient samples. The capture environments and seasons inferred by the otolith edge chemistry and marginal increase, respectively, suggest a location in high salinity water (estuary and sea) in summer. Finally, to estimate the size of archaeological fish, a linear regression between total length and otolith length was constructed using 70 modern catfish otoliths. The size variability (358–610 mm) might indicate the use of non-selective capture techniques, probably nets, by hunter-gatherer groups.Fil: Avigliano, Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Unidad Ejecutora de Investigaciones en Producción Animal. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Unidad Ejecutora de Investigaciones en Producción Animal; ArgentinaFil: Martinez, Gustavo Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Investigaciones Arqueológicas y Paleontológicas del Cuaternario Pampeano. Universidad Nacional del Centro de la Provincia de Buenos Aires. Investigaciones Arqueológicas y Paleontológicas del Cuaternario Pampeano; ArgentinaFil: Stoessel, Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Investigaciones Arqueológicas y Paleontológicas del Cuaternario Pampeano. Universidad Nacional del Centro de la Provincia de Buenos Aires. Investigaciones Arqueológicas y Paleontológicas del Cuaternario Pampeano; ArgentinaFil: Méndez, Ana. Universidad de Oviedo; EspañaFil: Bordel, Nerea. Universidad de Oviedo; EspañaFil: Pisonero, Jorge. Universidad de Oviedo; EspañaFil: Volpedo, Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Unidad Ejecutora de Investigaciones en Producción Animal. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Unidad Ejecutora de Investigaciones en Producción Animal; Argentin

Effect of glyphosate on growth and reproduction of higher crustaceans

El glifosato es el herbicida más utilizado actualmente en Argentina, y sus efectos deletéreos a largo plazo sobre los organismos acuáticos que se encuentran potencialmente expuestos, recién comienzan a conocerse. Los objetivos del presente trabajo fueron determinar los efectos subletales de glifosato (ácido y/o una formulación comercial): -sobre la tasa de crecimiento, los niveles de las principales reservas energéticas y la actividad de algunas enzimas del metabolismo intermedio en juveniles de C. quadricarinatus; -sobre el potencial reproductivo de hembras adultas de N. granulata; - sobre la incubación del desove y la eclosión larval en tres especies de crustáceos con diferente tipo de desarrollo (directo o indirecto). En juveniles tempranos de Cherax quadricarinatus expuestos a glifosato ácido, la ganancia en peso, los niveles de varias reservas energéticas y la actividad enzimática indicaron, en conjunto, un cuadro de estrés crónico asociado a una depresión metabólica, así como a un posible daño tisular. Al evaluar, tanto in vivo como in vitro, los efectos del herbicida sobre el crecimiento ovárico de Neohelice granulata se observó, a concentraciones relativamente bajas de glifosato ácido y tiempos de exposición relativamente prolongados (período pre-reproductivo de tres meses), un aumento de las reabsorciones oocitarias, mientras que a concentraciones mayores y tiempos más cortos (remaduración gonadal) se observó una estimulación del crecimiento ovárico, sugiriendo que el glifosato podría actuar como un desorganizador endocrino. Algunos resultados obtenidos in vitro aportaron también evidencias a favor de esta hipótesis. Finalmente, se evaluaron los efectos del glifosato sobre la progenie. Las larvas eclosionadas de hembras ovígeras de N. granulata expuestas a glifosato formulado (Roundup Ultramax®), se redujeron en número y presentaron varias anormalidades morfológicas. Los juveniles del camarón Neocaridina heteropoda heteropoda metabolizaron menos vitelo durante el desarrollo embrionario, por efecto de glifosato ácido, mientras que los estadios embrionarios tardíos de C. quadricarinatus se vieron afectados en su sobrevida y crecimiento, aunque a concentraciones relativamente elevadas del formulado.Glyphosate is the herbicide currently most used in Argentina, whose long-term deleterious effects on the aquatic organisms potentially exposed, are just beginning to be studied. The aims of this work were to determine the sublethal effects of glyphosate (acid and/or a commercial formulation): on the growth rate, levels of the main energy reserves and the activity of some enzymes of intermediate metabolism in juveniles of C. quadricarinatus; -on the reproductive potential of adult females of N. granulata; -on incubation of spawning and larval hatching in three crustacean species with different types of development (direct or indirect). In early juveniles of Cherax quadricarinatus exposed to acid glyphosate, several variables such as weight gain, levels of energetic reserves and enzymatic activity indicated a chronic stress syndrome, associated to both a metabolic depression and tissue damage. After evaluating, both in vivo and in vitro, the effects of the herbicide on the ovarian growth of Neohelice granulata, an increase of oocyte reabsorption was seen at relatively low concentrations and longer times of exposure to acid glyphosate (three months of pre-reproductive period), while stimulation of the ovarian growth was observed at higher concentrations and lower times of exposure (gonad re-maturation), suggesting that glyphosate could act as an endocrine disrupter. Some results obtained in vitro also provided evidence supporting this hypothesis. Finally, the effects of glyphosate on the progeny were also evaluated. Larvae hatched from N. granulata ovigerous females exposed to formulated glyphosate (Roundup Ultramax®) decreased in number, also presenting several morphological abnormalities. Juveniles of the shrimp Neocaridina heteropoda heteropoda metabolized less amount of vitellum during the embryonic development, by effect of acid glyphosate, while late embryonic instars of C. quadricarinatus were affected in their survival and growth, although at relatively high concentrations of the commercial formulation.Fil: Avigliano, Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentin

Dietary phytochemicals and drugs: potential consequences of a common metabolism.

Dietary phytochemicals and prescription drugs are xenobiotics to human cells and are substrates of the same enzymes and transporters dedicated to biotransformation, detoxification and elimination. The interactions between phytochemicals and phase I and II biotransformation enzymes, as well as their systems of regulation, can often explain their known anticarcinogenic or antioxidant actions. However, for the same reason the contemporaneous intake of phytochemicals and drugs may result in the alteration of drug biodisposition and efficacy. In the present chapter the principal routes of biotransformation are described, as well as the mechanisms underlying their concerted regulation, and the biotransformation of the most significant phytochemicals is reported. Examples of phytochemicals/drugs interaction are illustrated and the importance of this issue for phytochemical supplementation is pointed out