Abstract:

A key event in the generation of a cellular response against malicious organisms through the endocytic pathway is binding of peptidic antigens by major histocompatibility complex class II (MHC class II) molecules. The bound peptide is then presented on the cell surface where it can be recognized by T helper lymphocytes. NetMHCIIpan is a state-of-the-art method for the quantitative prediction of peptide binding to any human or mouse MHC class II molecule of known sequence. In this paper, we describe an updated version of the method with improved peptide binding register identification. Binding register prediction is concerned with determining the minimal core region of nine residues directly in contact with the MHC binding cleft, a crucial piece of information both for the identification and design of CD4+ T cell antigens. When applied to a set of 51 crystal structures of peptide-MHC complexes with known binding registers, the new method NetMHCIIpan-3.1 significantly outperformed the earlier 3.0 version. We illustrate the impact of accurate binding core identification for the interpretation of T cell cross-reactivity using tetramer double staining with a CMV epitope and its variants mapped to the epitope binding core. NetMHCIIpan is publicly available at http://www.cbs.dtu.dk/services/NetMHCIIpan-3.1.

Author affiliation: Andreatta, Massimo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas (subsede Chascomús) | Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas (subsede Chascomús); Argentina

Author affiliation: Karosiene, Edita. La Jolla Institute for Allergy and Immunology; Estados Unidos

Author affiliation: Rasmussen, Michael. Universidad de Copenhagen; Dinamarca

Author affiliation: Stryhn, Anette. Universidad de Copenhagen; Dinamarca

Author affiliation: Buus, Søren. Universidad de Copenhagen; Dinamarca

Author affiliation: Nielsen, Morten. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas (subsede Chascomús) | Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas (subsede Chascomús); Argentina. Technical University of Denmark; Dinamarca

Abstract:

Este trabajo de tesis esta focalizado en dos aspectos centrales: el calculo de propiedades electrónicas de sistemas de baja dimensionalidad utilizados en transporte electrónico a través de nanoestructuras y el otro refiere a problemas de adsorción de átomos en superficies metálicas. En el caso de transporte electrónico a través de junturas atómicas o moleculares es importante conocer la forma y orientación cristalina de los contactos lo que define posibles canales de conducción. En este sentido hemos estudiado las geometrías: puntas piramidales crecidas en las direcciones Pd(001) y Pd(111) y las superficies Pd(001) y Pd(111). En el caso de la adsorción de átomos sobre superficies metálicas, elegimos estudiar teoricamente el caso de S/Au(111) dado que presenta un rico escenario experimental de situaciones de adsorción conforme cambia la temperatura de la muestra y su recubrimiento. La herramienta principal que hemos utilizado es un código de cálculo ab-initio (FIREBALL), basado en DFT, en el cual hemos utilizado la aproximación LDA para la parte de correlación e intercambio. Este programa además realiza dinámica molecular a temperaturas diferentes de cero. Complementariamente hemos profundizado el uso y aplicación del modelo de enlaces de a pares, el cual esta basado en un hamiltoniano tipo Anderson con aproximación Hartree-Fock y donde los términos de dicho hamiltoniano son calculados a partir de las funciones atómicas de cada uno de los agentes interactuantes, superficie - adsorbato. En este caso el sistema estudiado fue el de adsorción de átomos de hidrógeno sobre superficies de Al(111) y Al(001).

This thesis is focused in two important aspects of surface physics and nanoscopic systems: the calculation of electronic properties low dimensional systems, used in electronic transport through of nanostructures; and the adsorption of atoms on metallic surfaces. In the electric transport through atomic or molecular junction is very important to know the contact forms and the crystalline orientation, since they can define channels of conduction. In this sense, we examine different geometries of contacts of palladium, pyramidal lead grown following (001) and (111) directions, and the surfaces Pd(001) and Pd(111). In the adsorption of atoms on metallic surfaces, we choose study theoreticaly the case of sulfur adsorbed on Au(111). This complex represents an active research area in which, depending on the coverage and the temperature, a very rich variety of superficial sulfur structures and adsorption properties are reported. The calculations have been done in the frame of the LDA for the exchange-correlation functional to the DFT applied to systems with or without translational periodicity. We use the FIREBALL code. This program, is a realization of a tight-binding DFT approach complemented with a molecular dynamic allowing calculations at temperatures different to cero. Complementary, we have improved the use and application to the own developed Bond-Pair model. Based in a Anderson’s model Hamiltonian (solved here whithin a Hartree-Fock approximation), the terms of the Hamiltonian are calculated from the atomic functions of each interacting agents, adsorbate-surface. In this case, the studying system was the adsorption of atoms to hydrogen on surfaces Al (111) and Al(001).

Consejo Nacional de Investigaciones Científicas y Técnicas

Abstract:

A parametric study on the stability performance of a prototypical natural circulation BWR is performed with the downscaled GENESIS facility. The GENESIS design is based on fluid-to-fluid modeling and includes an artificial void reactivity feedback (VRF) system for simulating the neutronic-thermal-hydraulic coupling. In this work a more sophisticated VRF system than its predecessors is developed and implemented. The VRF allowed investigating different configurations relevant for the reactor design. The experiments show that changing the fuel rods diameter to a half (doubling) decreases (increases) the stability performance of the system while the resonance frequency increases (decreases). In addition, it is found that the use of MOX fuels in a BWR slightly decreases the stability performance of the reactor. On top of this, it is clearly observed that at least two oscillatory modes exists in the system, the thermal-hydraulic mode (associated to density waves traveling thorough the core plus chimney section) and the so-called reactor mode (related to density waves travelling thorough the core). It is observed that the last one is amplified by increasing (in an absolute sense) the void reactivity feedback coefficient. Details regarding the interplay between these oscillatory modes is also given.

Author affiliation: Marcel, Christian Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina

Author affiliation: Rohde Scheel, María Eugenia. Delft University of Technology; Países Bajos

Author affiliation: Van Der Hagen, T. H. J. J.. Delft University of Technology; Países Bajos

Abstract:

El proyecto de tesis analiza las modificaciones de la respuesta astroglial postlesional, en modelos in vitro e in vivo. El Capitulo I describe el estudio de la respuesta astroglial a la lesión en modelos in vitro a fin de evaluar su modulación por las condiciones de cultivo. Tal respuesta, dependería de la interrupción de la inhibición por contacto celular, y no por señales mitogénicas astrogliales liberadas en el sitio de la herida. El Capítulo II contempla el análisis de los efectos postlesionales a distancia sobre el gliopilo luego de una lesión cortical en monos Cebus apella. La lesión cortical focalizada dio lugar a una respuesta de incorporación nuclear de BrdU predominante en láminas supragranulares de áreas corticales distantes y relacionadas funcionalmente con el área lesionada. El tipo celular involucrado en dicha respuesta a distancia no se logró especificar con los marcacdores celulares analizados, por lo que serían necesarios estudios adicionales. El Capítulo III expone el análisis de la modulación de la reactividad astroglial postlesional por exposición a una condición de Enriquecimiento Ambiental (EA), en ratas Sprague- Dawley. La exposición de los animales a EA en la etapa de desarrollo postnatal previa a la lesión, disminuyó la astrogliosis reactiva postlesional sugiriendo el impacto favorable de esta condición sobre los procesos de reorganización cortical postlesional. El aumento de la inmunomarcación de ezrina cortical de las ratas expuestas a EA, pudo haber sido impulsado por la formación de nuevas sinapsis, o el refuerzo de la participación astroglial en las sinapsis existentes. La lesión interfirió con este efecto cuando ambos tratamientos se aplicaron juntos en el grupo experimental.

The thesis project focused on analyzing changes on astroglial postlesional response in in vitro and in vivo models. Chapter I describes the study of astroglial response to injury in in vitro models, to assess its modulation by culture conditions. Such in vitro response would depend on the disruption of cell contact inhibition, but not on astroglial mitogenic signals released into the wound site. Chapter II provides an analysis of the postlesional effects on the gliopilo at remote sites after a cortical injury in Cebus apella monkeys. Focal cortical lesions resulted in a BrdU nuclear incorporation response predominantly in supragranular layers of cortical areas distant and functionally related to the injured area. Specification of the cellular type involved in this remote response was not achieved with the cellular markers analyzed, so further studies are needed. Chapter III presents the analysis of the astroglial postlesional reactivity modulation by exposure to an Environmental Enrichment (EE) condition, in Sprague-Dawley rats. The exposure of animals to EE during postnatal development and previous to the lesion, decreased postlesional reactive astrogliosis suggesting the favorable impact of this condition on the postlesional cortical reorganization. Increased cortical ezrin immunostaining in rats exposed to EE could have been driven by the formation of new synapses or the reinforcement of astroglial involvement in the existing ones. The injury interfered with this effect when both treatments were applied together in the experimental group.

Author affiliation: Lanosa, Ximena Alejandra. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

Abstract:

Se estudió el desempeño de catalizadores novedosos de metales soportados (Pd y Cu), promovidos con galio, en la síntesis de metanol por hidrogenación selectiva, a partir de mezclas ricas en dióxido de carbono (CO2). Se simuló un módulo de recuperación de CO2 alimentado por mezclas H2/CO2 y con reciclo de gases incondensables. En “equilibrio termodinámico” y en condiciones industriales de proceso la recuperación sería cercana al 100 %. Con catalizadores comerciales (CuO/ZnO/Al2O3) sería superior al 50 % mientras que con un catalizador novedoso basado en paladio (Ga2O3-Pd/SiO2) ésta sería menor debido –en parte- a la quimisorción de CO en el Pd lo que limita la capacidad hidrogenante. Se evaluó la actividad catalítica de nuevos catalizadores binarios y ternarios compuestos por Cu-Zr-Ga, desarrollados en INTEC. Los de mejores desempeños (más activos, selectivos y estables) fueron aquellos en los que la galia es agregada al precursor Cu/ZrO2 seco y calcinado, habiéndose incorporando el metal por intercambio iónico (Ga2O3-Cu/ZrO2). Para obtener información cinética y mecanística de los catalizadores Cu/ZrO2 y Ga2O3-Cu/ZrO2 se diseñó un microrreactor Carberry apto para determinar velocidades iniciales de reacción y realizar estudios con isótopos. Se ponderó la capacidad hidrogenante de los catalizadores mediante intercambio isotópico (H/D). Se concluyó que la provisión de hidrógeno no es limitante en la síntesis de metanol. Se analizó la reacción reversa de gas de agua (RWGS) con mezclas de H2(D2)/CO2/Ar lo que permitió inferir que la RWGS ocurre principalmente en la superficie del cobre. Estos resultados permitieron explicar la mayor selectividad del catalizador ternario.

The performance of novel metal supported catalysts (Pd and Cu), promoted with gallium, in the methanol synthesis by selective hydrogenation from CO2-rich mixtures was studied. A CO2 capture module, with H2/CO2 feed and recycle of condensable gases, was simulated. Under "thermodynamic equilibrium" and industrial process conditions the CO2 capture would be close to 100%. With commercial catalysts (CuO/ZnO/Al2O3) it would be greater than 50% whereas with a novel palladium catalyst (Ga2O3-Pd/SiO2) it would be lower due to –partly- the CO chemisorption on Pd which limits the hydrogenating capacity. The catalytic activity of new binary and ternary Cu-Zr-Ga catalysts, developed in INTEC, was evaluated. The best performance (more active, selective and stable) was achieved by those in which gallium is added to the dry and calcined Cu/ZrO2 precursor, having incorporated the metal by ion exchange (Ga2O3-Cu/ZrO2). In order to obtain kinetic and mechanistic information of Cu/ZrO2 and Ga2O3-Cu/ZrO2 catalysts, a Carberry microreactor suitable to determine initial rates of reaction and to carry out isotopic studies was designed. The hydrogenating capacity of the catalysts was considered by isotopic exchange (H/D). It was concluded that the hydrogen supply is not limited in the methanol synthesis. The reverse water gas shift reaction (RWGS) was also tested with mixtures of H2(D2)/CO2/Ar. It was inferred that the RWGS occurs primarily on the copper surface. These results allowed to explain the greater selectivity of the ternary catalyst.

Consejo Nacional de Investigaciones Científicas y Técnicas

Agencia Nacional de Promoción Científica y Tecnológica

Abstract:

The gas-phase reaction of Cl atom with 2,2,2-trifluoroethylacrylate (k1), 1,1,1,3,3,3-hexafluoroisopropylacrylate (k2), 2,2,2-trifluoroethylmethacrylate (k3) and 1,1,1,3,3,3-hexafluoroisopropylmethacrylate (k4), have been investigated at 298 K and 1 atm using the relative method by gas chromatography coupled with flame ionization detection (GC-FID). The values obtained are (in cm3 molecule−1 s−1): k1(Cl+CH2=CHC(O)OCH2CF3) = (2.41 ± 0.57) × 10−10, k2(Cl+CH2=CHC(O)OCH(CF3)2) = (1.39 ± 0.34) × 10−10, k3(Cl+CH2=C(CH3)C(O)OCH2CF3) = (2.22 ± 0.45) × 10−10, and k4(Cl +CH2=C(CH3)C(O)OCH(CF3)2 = (2.44 ± 0.52) × 10−10. Products identification studies were performed by solid-phase microextraction (SPME) method, with on-fiber products derivatization using o-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine hydrochloride, coupled with gas chromatography with mass spectrometry detection (GC-MS). Chloroacetone, trifluoroacetaldehyde and formaldehyde were observed as degradation products and a general mechanism is proposed. Additionally, reactivity trends and atmospheric implications are discussed. Significant ozone photochemical potentials (POCP) and acidification potentials lead to local and or regional impact of the esters under study although is expected to a have a minor impact on global warming and climate change.

Author affiliation: Rivela Fretes, Cynthia Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina

Author affiliation: Blanco, Maria Belen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina

Author affiliation: Teruel, Mariano Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina

Abstract:

Startle is a fast response elicited by sudden acoustic, tactile or visual stimuli in a variety of animal species and in humans. The magnitude of startle response can be modulated by external and internal variables and can be a useful tool to study the sensory-motor integration in animals. Different stimuli have been used to induce startle in horses, which makes it difficult to compare the responses to these different approaches. The present study uses ultra-short-term heart rate variability (HRV) analysis to characterize the cardiac autonomic modulation, reactivity assessment and blood cortisol measurements to describe the behavioural and endocrine responses to a simple, easy to replicate, effective and safe method of startle (an umbrella is abruptly opened near the horse). The ultra-short-term (64 s) heart rate (HR) series were interpolated (4 Hz) and divided into 256 points segments then the spectra calculated (Fast Fourier Transform). The spectra were then integrated into low (LF; 0.01–0.07 Hz; Index of Cardiac Sympathetic Modulation) and high (HF; 0.07–0.50 Hz;Index of Cardiac Parasympathetic Modulation)frequency bands. Following the startle test, the HR (p = 0.0101), the power of the LF band of the cardiac interval spectrum (p = 0.0002) and the LF/HF ratio (p = 0.0066) were found to be higher, whereas the power of the HF band of the cardiac interval spectrum was found to be lower (p = 0.0002). Also, the horses showed a noticeable escape response, with latency of reaction varying from 0.28 to 1.28 s, duration of reaction ranging from 1.52 to 7.92 s and escape distance covered varying from 3.43 to 9.97 m. However, the endocrine measurements failed to reveal significant changes in the cortisol levels after the startle test. We conclude that the startle test used in the current study was effective to produce changes in behavioural parameters and cardiac autonomic modulation of the horses and can therefore be an appropriate tool for neurobiological studies. Furthermore, the use of ultra-short segments (64 s) for HRV analysis appears to be effective and promising for the detection of mental stress in horses.

Author affiliation: Villas Boas, Julia Dias. Universidade Federal do Rio de Janeiro; Brasil

Author affiliation: Dias, Daniel Penteado Martins. Universidade de Sao Paulo; Brasil

Author affiliation: Trigo, Pablo Ignacio. Universidade Federal do Rio de Janeiro; Brasil. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Author affiliation: dos Santos Almeida, Norma Aparecida. Universidade Federal do Rio de Janeiro; Brasil

Author affiliation: Queiroz de Almeida, Fernando. Universidade Federal do Rio de Janeiro; Brasil

Author affiliation: Alves de Medeiros, Magda. Universidade Federal do Rio de Janeiro; Brasil

Abstract:

Startle is a fast response elicited by sudden acoustic, tactile or visual stimuli in a variety of animal species and in humans. The magnitude of startle response can be modulated by external and internal variables and can be a useful tool to study the sensory-motor integration in animals. Different stimuli have been used to induce startle in horses, which makes it difficult to compare the responses to these different approaches. The present study uses ultra-short-term heart rate variability (HRV) analysis to characterize the cardiac autonomic modulation, reactivity assessment and blood cortisol measurements to describe the behavioural and endocrine responses to a simple, easy to replicate, effective and safe method of startle (an umbrella is abruptly opened near the horse). The ultra-short-term (64 s) heart rate (HR) series were interpolated (4 Hz) and divided into 256 points segments then the spectra calculated (Fast Fourier Transform). The spectra were then integrated into low (LF; 0.01–0.07 Hz; Index of Cardiac Sympathetic Modulation) and high (HF; 0.07–0.50 Hz; Index of Cardiac Parasympathetic Modulation) frequency bands. Following the startle test, the HR (p = 0.0101), the power of the LF band of the cardiac interval spectrum (p = 0.0002) and the LF/HF ratio (p = 0.0066) were found to be higher, whereas the power of the HF band of the cardiac interval spectrum was found to be lower (p = 0.0002). Also, the horses showed a noticeable escape response, with latency of reaction varying from 0.28 to 1.28 s, duration of reaction ranging from 1.52 to 7.92 s and escape distance covered varying from 3.43 to 9.97 m. However, the endocrine measurements failed to reveal significant changes in the cortisol levels after the startle test. We conclude that the startle test used in the current study was effective to produce changes in behavioural parameters and cardiac autonomic modulation of the horses and can therefore be an appropriate tool for neurobiological studies. Furthermore, the use of ultra-short segments (64 s) for HRV analysis appears to be effective and promising for the detection of mental stress in horses.

Author affiliation: Villas Boas, Julia Dias. Universidade Federal Rural de Rio de Janeiro; Brasil

Author affiliation: Martins Dias, Daniel Penteado. Universidade de Sao Paulo; Brasil

Author affiliation: Trigo, Pablo Ignacio. Universidade Federal Rural de Rio de Janeiro; Brasil. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Author affiliation: dos Santos Almeida, Norma Aparecida. Universidade Federal Rural de Rio de Janeiro; Brasil

Author affiliation: de Almeida, Fernando Queiroz. Universidade Federal Rural de Rio de Janeiro; Brasil

Author affiliation: de Madeiros, Magda Alves. Universidade Federal Rural de Rio de Janeiro; Brasil

Abstract:

Abstract This study evaluated the effects of a Zuccagniapunctata standardized hydroalcoholic extract (ZpE) and threeof its major flavonoids [2′,4′-dihydroxychalcone (DHC), 7-hydroxyflavanone (HF) and 3,7-dihydroxyflavone (DHF)] onthe vascular reactivity of aortic rings with endothelial dysfunctioninduced by feeding rabbits on a high cholesteroldiet. Rabbits were fed with either normal chow or a dietcontaining 1% cholesterol for 5?6 weeks. Isometric contractionswere measured. Concentration response curves to ZpE(range from 4×10−2 to 4 ×10 μg gallic acid equivalent/ml),DHC, DHF or HF (range from 10−9 to 10−4 M) showedconcentration-dependent relaxation of arteries pre-contractedwith phenylephrine. ZpE (4×10−2, 4 ×10−1 and 4 μg gallicacid equivalent/ml), HF (10−9, 10−7, 10−5 M), DHC (10−9M) and DHF (10−9 M) added to the bath improved acetylcholineaffinity. Pre-treatment of arteries with ZpE (4×10−2 μg gallic acid equivalent/ml) and DHC (10−9 M)reduced phenylephrine-induced contraction. Incubationwith the higher dose of ZpE (4 μg gallic acid equivalent/ml)reduced the angiotensin II-maximal contraction (Cmax) actingas a non-competitive antagonist, while DHC and DHF(10−5 M) caused a non-parallel rightward of the angiotensinII-concentration response curves and reduced the Cmaxacting as mixed antagonists. ZpE (4 × 10−2 μg gallic acidequivalent/ml), DHC and DHF (10−9 M) caused a rightwarddisplacement of angiotensin II-concentration responsecurves acting as competitive antagonists. In conclusion, thepresent study demonstrated that a ZpE and its major flavonoidshad beneficial effects in arteries with vasculardysfunction induced by hypercholesterolemia. Therefore itsuse as herbal medicine to prevent cardiovascular risks factorsmay be promising.

Author affiliation: Roco, Julieta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina

Author affiliation: Alarcón, Gabriela del Jesús. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina

Author affiliation: Sierra, Liliana Beatríz. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; Argentina

Author affiliation: Zampini, Iris Catiana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; Argentina

Author affiliation: Isla, Maria Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; Argentina

Author affiliation: Jerez, Susana Josefina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; Argentina

Abstract:

The taste reactivity test is considered as an objective measure to assess the hedonic impact of tastes. Both the appetitive and aversive pattern of responses are plastic and can change based on previous experience. The present study assessed the repertoire of taste responses elicited by sucrose and quinine in preweanling rats, and described changes in these taste reactivity patterns after exposure to the other tastant. We exposed infant rats (17 days old at the start of training) to sweet (2% sucrose) or bitter (0.01% quinine) tastants during 4, 10-min trials in two different random sequences. The subjects were weighed before and after each trial to provide a measure of percent body weight gained. The following taste reactivity responses were registered: duration of mouthing and paw lick, frequency of chin rub, head shake and flailing of the forelimbs, frequency and duration of face washing, wall climbing and paw tread. The consummatory and affective taste responses changed depending on the order in which the solutions were administered. The order of exposure to the tastants did not affect the levels of sucrose intake. Conversely, rat pups showed more ingestive, and fewer aversive, responses to the sweet tastant when access to the solution followed the intraoral infusion of quinine. Likewise, intraoral delivery of quinine elicited a more aversive taste reactivity pattern when delivered after the access to sucrose than when presented to sucrose-naïve pups. This research contributes to the analysis of taste reactivity responses during the early ontogeny of the rat and highlights the importance of previous experiences on the subsequent assessment of rewards.

Author affiliation: Suarez, Andrea Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Médicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Médicas; Argentina. Universidad Abierta Interamericana; Argentina

Author affiliation: Ifrán, María Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Médicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Médicas; Argentina. Universidad Abierta Interamericana; Argentina

Author affiliation: Pautassi, Ricardo Marcos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra. Universidad Nacional de Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra; Argentina

Author affiliation: Kamenetzky, Giselle Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Médicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Médicas; Argentina. Universidad Abierta Interamericana; Argentina