Exploring artificial photosynthesis : reductive processes on surfaces

[Resumen] El aumento cada vez mayor de la concentración de CO2 en todo el planeta preocupa enormemente por su implicación en el efecto invernadero y sus consecuencias. Por este motivo, en la actualidad existen varias líneas de investigación que buscan reducir su concentración en la atmósfera. Una de ellas es su transformación mediante fotorreducción bajo la luz solar en otros compuestos menos perjudiciales y que puedan resultar útiles; pero para ello es necesario sintetizar catalizadores activados por la luz solar que sean capaces de llevar a cabo dicha reacción con éxito, tarea relacionada con el área de la fotoquímica y fotocatálisis y en la que se centra este proyecto. Así pues, en el presente Trabajo de Fin de Grado se llevó a cabo la síntesis y caracterización de nanopartículas de ZnO y ZnO funcionalizado con monoetanolamina (MEA) con el propósito de utilizarlas como fotocatalizadores para la reducción de CO2 a otros derivados como CO, HCO2H, HCHO, CH3OH y CH4; y comparar sus rendimientos. Para caracterizar los productos obtenidos se utilizaron las siguientes técnicas: difracción de rayos X en polvo (DRX-P), fluorescencia de rayos X (FRX), espectroscopía de IR (FT-IR), microscopía electrónica de transmisión (MET) y de barrido (MEB), adsorción de N2 y espectroscopía de reflectancia difusa UV-Vis (ERD). La composición de los gases resultantes de la fotorreducción fue seguida mediante cromatografía de gases (CG). Se comprobó que ambos productos sintetizados se correspondían a nanopartículas de ZnO de estructura wurzita con un 98% de pureza y eran activados con la luz solar. Además, el producto funcionalizado efectivamente estaba enlazado covalentemente a la MEA y obtenía una mayor adsorción de N2 frente al ZnO. El procedimiento, en su conjunto, apunta a la existencia de un proceso de fotorreducción de CO2. Sin embargo, no fue posible llevar a cabo comparaciones entre la eficiencia de ambos catalizadores, dado que los productos esperados estaban por debajo del límite de detección[Resumo] O aumento cada vez maior da concentración de CO2 en todo o planeta preocupa enormemente pola súa implicación no efecto invernadoiro e as súas consecuencias. Por este motivo, na actualidade existen varias liñas de investigación que buscan reducir a súa concentración na atmosfera. Unha delas é a súa transformación mediante fotorreducción baixo a luz solar noutros compostos menos prexudiciais e que poidan resultar útiles; pero para iso é necesario sintetizar catalizadores activados pola luz solar que sexan capaces de levar a cabo dita reacción con éxito, tarefa relacionada coa área da fotoquímica e fotocatálise e na que se centra este proxecto. Así pois, no presente Traballo de Fin de Grao levouse a cabo a síntese e caracterización de nanopartículas de ZnO e ZnO funcionalizado con monoetanolamina (MEA) co propósito de utilizalas como fotocatalizadores para a redución de CO2 a outros derivados como CO, HCO2H, HCHO, CH3OH e CH4; e comparar os seus rendementos. Para caracterizar os produtos obtidos utilizáronse as seguintes técnicas: difracción de raios X en po (DRX-P), fluorescencia de raios X (FRX), espectroscopia de IR (FT-IR), microscopia electrónica de transmisión (MET) e de varrido (MEV), adsorción de N2 e espectroscopia de reflectancia difusa UV-Vis (ERD). A composición dos gases resultantes da fotorreducción foi seguida mediante cromatografía de gases (CG). Comprobouse que ambos os produtos sintetizados correspondíanse a nanopartículas de ZnO de estrutura wurzita cun 98% de pureza e eran activados coa luz solar. Ademais, o produto funcionalizado efectivamente estaba enlazado covalentemente á MEA e obtiña unha maior adsorción de N2 fronte ao ZnO. O procedemento, no seu conxunto, apunta á existencia dun proceso de fotorreducción de CO2. Con todo, non foi posible levar a cabo comparacións entre a eficiencia dos dous catalizadores, dado que os produtos esperados estaban por baixo do límite de detección.[Abstract] The worlwide increase of CO2 concentration is highly worrying, due to its involvement in greenhouse effect and the corresponding consequences. For this reason, there are currently several research lines aiming to reduce CO2 concentration in the atmosphere. One of these is its photoreductive transformation to less environmentally lesive (and more useful) compounds using sunlight. For this, it is necessary to use catalysts that may be photoactivated by sunlight and that are able to successfully perform this reaction. This is fully involved in the fields of photochemistry and photocatalysis for Green Chemistry purposes, the core of this project. In this End of Degree Thesis we carried out the synthesis and characterization of ZnO and monoethanolamine (MEA)-functionalized ZnO nanoparticles, with the aim to used them as photocatalysts for the reduction of CO2 to other derived molecules, such as CO, HCO2H, HCHO, CH3OH or, ideally, CH4, and to compare their yields. To characterize the obtained products we used the following techniques: X-ray powder diffraction (XRD), X-ray fluorescence (XRF), Fourier transformed IR spectroscopy (FT-IR), transmission electron microscopy (TEM) and scanning electron microscopy (SEM), N2 adsorption and diffuse reflectance spectroscopy (DRS). The final gas composition after photoreductin was followed by gas chromatography (GC). Both synthesized photocatalysts showed a wurzite ZnO structure, with 98% purity and were sunlight activated. Besides, the functionalized catalyst was covalently bonded to MEA and showed a higher N2 adsorption as compared to ZnO. The procedure, as a whole, points to the existence of a photoreduction of CO2. However, it was not possible to carry out efficiency comparisons between both catalysts, as the expected products were below detection limits.Traballo fin de grao (UDC.CIE). Química. Curso 2015/201

Análisis de dos sistemas acuáticos : un enfoque ecohidrológico

Se aplicó el concepto de ecohidrología en dos cuencas: río Paraná Inferior y Arroyo Durazno con el objeto de estudiar las respuestas biogeoquímicas en ambos sistemas diferenciados por área de drenaje, magnitud de caudal y uso de la tierra. La primera presenta una amplia llanura aluvial (12.350 km2) vegetada por macrófitas. Durante las crecientes estivales, las condiciones favorecen la denitrificación en humedales y disminución de nitratos en cauce principal, siendo el intervalo de mayor frecuencia 25-108,3 μg N-NO3 -/l en aguas altas y 191,6-274,9 μg N-NO3 -/l en aguas bajas. Durante una creciente invernal (El Niño 1991-1992) se detectó correlación positiva significativa entre concentraciones de nitratos y amonio y altura hidrométrica. El arroyo Durazno (360 km2) no recibe aporte directo de contaminantes y presenta una rápida respuesta ante un evento de precipitación. En las primeras horas de la tormenta las concentraciones de nitratos y fósforo reactivo soluble (PRS) fueron mayores que al finalizar, debido al aporte por escorrentía. Los resultados revelan el efecto del valle aluvial sobre la hidroquímica de los cauces principales. El análisis muestra que cambios en componentes del ciclo hidrológico y/o en el uso de la tierra podrían alterar la calidad de aguas aun en cuencas de extensiones y caudales diferentes.The concept of ecohydrology was applied to the Lower Paraná river and the El Durazno stream catchments in order to study the biogeochemistry responses of the two systems, which differ in their drainage area, discharge and land use. The first catchment presents a vast floodplain dominated by macrophyte (12,350 km2). During summer rise, denitrification in wetlands is favoured, producing nitrate concentration reduction in the main channel. The nitrate range most frequently found in high water levels was 25-108,3 μg N-NO3 -/l and in low water levels was 191,6-274,9 μg N-NO3 -/l. During a winter rise (El Niño 1991-1992), a significant positive correlation was detected between nitrate and ammonia concentrations and hydrometric height. The El Durazno stream (360 km2) does not receive any direct polluted flow and responds rapidly to precipitation events. During the first hours of the studied storm and as consequence of runoff, nitrate and phosphorous concentrations were higher than at the beginning. The results here revealed the effect of the alluvial valley on the main river bed hydrochemistry. The analysis showed that changes in water cycle and/or in land use may alter water quality, even in catchments of different extension and river discharge.Fil: De Cabo, Laura.Fil: Seoane, Rafael. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de HidráulicaFil: Arreghini, Silvana. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Recursos Naturales y AmbienteFil: Callau, Ana. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Hidráulic

Developmental Coordination Disorder, Motor Performance, and Daily Participation in Children with Attention Deficit and Hyperactivity Disorder

[Abstract] Children with Attention Deficit and Hyperactivity Disorder (ADHD) often present with Developmental Coordination Disorder (DCD) or motor coordination problems that further impact their daily functioning. However, little is known about the prevalence of co-occurring DCD and ADHD in the Spanish context, and research about the impact of ADHD on performance and participation in motor-based activities of daily living (ADL) is scarce. The aims of this study were to explore the prevalence of co-occurring DCD in children with ADHD, and to examine differences in performance and participation in motor-based ADL between children with ADHD and typically developing children. We conducted a case-control study including 20 children with ADHD and 40 typically developing controls randomly matched for exact age and sex (males = 80%; mean age = 8, 9 (2, 3) years). Presence of probable DCD (p-DCD) was confirmed with the Developmental Coordination Disorder Questionnaire (DCDQ). The DCDDaily-Q was administered to assess performance and participation in ADL. A 75% prevalence of p-DCD was found in the ADHD group (OR = 27; p < 0.001). Children with ADHD showed poorer motor performance and less participation in ADL (p < 0.01; d = 0.9–1.4). These findings contribute to understand the functional consequences of ADHD in motor-based ADL and its relationship with DCD.Xunta de Galicia; ED481A-2018/15

Assessment of cytotoxicity biomarkers on the microalga "Chlamydomonas reinhardtii" exposed to emerging and priority pollutants

[Abstract] Contamination of aquatic ecosystems linked to anthropogenic activity is currently a major concern; therefore, ecotoxicological studies are needed to assess its effect on organisms. The main objective of this study was to investigate the effects of different pollutants on microalgae in search of sensitive biomarkers that can promote a common cytotoxic response regardless of the contaminant. Cultures of the freshwater microalga Chlamydomonas reinhardtii were exposed for 24 h to four chemicals, three emerging pollutants (benzophenone-3, bisphenol A and oxytetracycline) and one priority substance (atrazine). A cytometric panel was carried out to assess toxicity biomarkers including cellular growth, inherent cell properties, viability, vitality, cytoplasmic membrane potential and ROS levels. Lipid peroxidation, photosynthetic efficiency and transcriptional responses of photosynthesis- and oxidative stress-related genes using RT-qPCR were also studied. Some toxicity responses showed a similar pattern; a decrease in growth rate, vitality and photosynthetic efficiency and an increase in autofluorescence and in the number of cells with depolarised cytoplasmic membrane and were found for all chemicals tested. However, ATZ and OTC provoked a decrease in cell size, whereas BP-3 and BPA caused an increase in cell size, intracellular complexity and ROS levels and a decrease in cell viability. Assayed pollutants generally promoted an overexpression of genes related to cellular antioxidant defence system and a subexpression of photosynthesis-related genes. In addition to the traditional growth endpoint, cell vitality, autofluorescence and gene expression of catalase, glutathione peroxidase and Fe-superoxide dismutase were significantly affected for all chemicals tested, showing a common cytotoxic response. Among the tested substances, BP-3 provoked the strongest cytotoxic alterations on this microalga, pointing out that some emerging contaminants could be more harmful to organisms than priority pollutants.Ministerio de Economía, Industria y Competitividad; CTM 2017- 88668-

Cytotoxicity of BP-3 and BP-4: Blockage of Extrusion Pumps, Oxidative Damage and Programmed Cell Death on Chlamydomonas reinhardtii

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract] The health concern associated with the dangers related to exposure to UV radiation has led to an increase in the use of sunscreens containing UV-filters that can reach aquatic environments and possibly affect ecosystems. Benzophenone-3 (BP-3) and benzophenone-4 (BP-4) are two of the most used UV-filters. In the present work, the microalga Chlamydomonas reinhardtii was exposed to several concentrations of both chemicals. To evaluate their potential cytotoxicity on microalgal cells, different parameters were analysed including fast response biomarkers (increase in intracellular free Ca2+) as well as biomarkers related with the presence of oxidative stress (lipid peroxidation), energy metabolism (photosynthetic yield and cytoplasmic lipid accumulations), cell division (proliferation and F-actin content), programmed cell death (PCD) (caspase activation and DNA fragmentation) and possible mechanisms of resistance to xenobiotics (operation of extrusion pumps and presence of autophagic vacuoles). Results showed an increment of the percentage of cells with cytosolic free Ca2+ that could act as a secondary messenger in response to the stress. A decrease in photosynthetic yield and an increase in cytoplasmic lipid accumulations and lipid peroxidation levels were also detected. In addition, a decrease in cell proliferation was observed, linked to a decrease in the percentage of cells with F-actin. The increase observed in the microalgal population with caspase activity, together with the DNA fragmentation and the alterations in the cytoskeleton, suggested the induction of processes linked to PCD. Moreover, a blockage of extrusion pumps, which could be related to the toxicity mechanism of these compounds, and an increase in autophagic vacuoles, as an attempt to repair the damage caused by benzophenones, were detected. Overall, these biomarkers indicate that both UV-filters can be a serious threat to non-target photosynthetic microorganisms in aquatic environments, although BP-3 affected C. reinhardtii more markedly.This research has been funded by Spanish “Ministerio de Economía, Industria y Competitividad” (CTM2017- 88668-R). M. S. and M. E. were funded by a grant from “Diputación Provincial de A Coruña

Toxicidad aguda de la plata sobre Cnesterodon decemmaculatus (Pisces: Poeciliidae) en un río con características extremas de calidad de agua

 A 96 h acute silver toxicity test was performed in order to determine silver toxicity (LC ) to a local fsh species (Cnester- 50 odon decemmaculatus) in a river with extreme water-quality characteristics (Pilcomayo River, South America) and evaluate a cross-fsh-species extrapolation of the Biotic Ligand Model. The dissolved silver concentrations tested were 0.095, 0.148, 0.175  calculated for C. decemmaculatus was 0.14 mg L and 0.285 mg Ag L . The 96 h Ag LC  (0.18 - 0.10) and the value predicted −1 −1 50 by BLM for Pimephales promelas was 0.051 mg Ag L . Test water elevated hardness may have exerted some protective effect. −1 High mean water pH may have exerted a major protective effect by reducing silver free ion form and causing silver precipitation. The mortality pattern observed in this toxicity test may lend some support to a relationship between gill silver accumulation and mortality. A cross-fsh-species extrapolation of Ag BLM for P. promelas was not valid in Pilcomayo River water and experimental conditions of this toxicity test. Con el objeto de determinar la toxicidad de la plata en un pez nativo (Cnesterodon decemmaculatus), se llevó a cabo un ensayo estático de toxicidad aguda a 96 horas en un agua natural con características de calidad de agua, extremas (río Pilcomayo, Sudamérica). Asimismo, se evaluó una posible extrapolación inter-especie del Modelo del Ligando Biótico en el agua experimental. La concentración inicial de plata en solución en los distintos tratamientos fue de 0,095; 0,148; 0,175 y 0,285 mg Ag L−1. La CL50 a las 96 horas calculada para C. decemmaculatus fue de 0,14 (0.18 - 0.10) mg Ag L−1 y el valor predicho por el BLM para Pimephales promelas fue de 0,051 mg Ag L−1. La elevada dureza del agua experimental pudo haber tenido algún efecto protector frente a la toxicidad de la plata. El valor medio de pH del ensayo fue elevado y posiblemente tuvo un gran efecto protector por reducción de la forma iónica libre y precipitación del metal. El patrón de mortalidad observado en este ensayo de toxicidad apoyaría la relación causa-efecto entre acumulación de plata en las branquias y mortalidad. La extrapolación inter-especie del BLM para P. promelas no resultó válida en el agua del río Pilcomayo y en las condiciones experimentales de este ensayo.Fil: Casares, Maria Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales; Argentina;Fil: de Cabo, Laura Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales; Argentina;Fil: Seoane, Rafael Santiago. Ministerio de Planificación Federal, Inversión Pública y Servicios. Secretaria de Obras Publicas. Subsecretaria de Recursos Hídricos. Instituto Nacional del Agua y del Ambiente (Ezeiza); Argentina; Universidad de Buenos Aires. Facultad de Ingeniería; Argentina;Fil: Natale, Oscar. Ministerio de Planificación Federal, Inversión Pública y Servicios. Secretaria de Obras Publicas. Subsecretaria de Recursos Hídricos. Instituto Nacional del Agua y del Ambiente (Ezeiza); Argentina

Toxicidad aguda de la plata sobre Cnesterodon decemmaculatus (Pisces: Poeciliidae)

A 96 h acute silver toxicity test was performed in order to determine silver toxicity (LC50) to a local fish species (Cnesterodon decemmaculatus) in a river with extreme water-quality characteristics (Pilcomayo River, South America) and evaluate a cross-fish-species extrapolation of the Biotic Ligand Model. The dissolved silver concentrations tested were 0.095, 0.148, 0.175 and 0.285 mg Ag L-1. The 96 h Ag LC50 calculated for C. decemmaculatus was 0.14 mg L-1 (0.18 - 0.10) and the value predicted by BLM for Pimephales promelas was 0.051 mg Ag L-1. Test water elevated hardness may have exerted some protective effect. High mean water pH may have exerted a major protective effect by reducing silver free ion form and causing silver precipitation. The mortality pattern observed in this toxicity test may lend some support to a relationship between gill silver accumulation and mortality. A cross-fish-species extrapolation of Ag BLM for P. promelas was not valid in Pilcomayo River water and experimental conditions of this toxicity test.Con el objeto de determinar la toxicidad de la plata en un pez nativo (Cnesterodon decemmaculatus), se llevó a cabo un ensayo estático de toxicidad aguda a 96 horas en un agua natural con características de calidad de agua, extremas (río Pilcomayo, Sudamérica). Asimismo, se evaluó una posible extrapolación inter-especie del Modelo del Ligando Biótico en el agua experimental. La concentración inicial de plata en solución en los distintos tratamientos fue de 0,095; 0,148; 0,175 y 0,285 mg Ag L -1 . La CL50 a las 96 horas calculada para C. decemmaculatus fue de 0,14 (0.18 - 0.10) mg Ag L-1 y el valor predicho por el BLM para Pimephales promelas fue de 0,051 mg Ag L-1. La elevada dureza del agua experimental pudo haber tenido algún efecto protector frente a la toxicidad de la plata. El valor medio de pH del ensayo fue elevado y posiblemente tuvo un gran efecto protector por reducción de la forma iónica libre y precipitación del metal. El patrón de mortalidad observado en este ensayo de toxicidad apoyaría la relación causa-efecto entre acumulación de plata en las branquias y mortalidad. La extrapolación inter-especie del BLM para P. promelas no resultó válida en el agua del río Pilcomayo y en las condiciones experimentales de este ensayo.Fil: Casares, Maria Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales; ArgentinaFil: de Cabo, Laura Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales; ArgentinaFil: Seoane, Rafael Santiago. Ministerio de Planificación Federal, Inversión Pública y Servicios. Secretaria de Obras Publicas. Subsecretaria de Recursos Hídricos. Instituto Nacional del Agua y del Ambiente (Ezeiza); Argentina. Universidad de Buenos Aires. Facultad de Ingeniería; ArgentinaFil: Natale, Oscar. Ministerio de Planificación Federal, Inversión Pública y Servicios. Secretaria de Obras Publicas. Subsecretaria de Recursos Hídricos. Instituto Nacional del Agua y del Ambiente (Ezeiza); Argentin

Functional connectivity of the hippocampus and its subfields in resting-state networks

First published: 30 March 2021Many neuroimaging studies have shown that the hippocampus participates in a resting-state network called the default mode network. However, how the hippocampus connects to the default mode network, whether the hippocampus connects to other resting-state networks and how the different hippocampal subfields take part in resting-state networks remains poorly understood. Here, we examined these issues using the high spatial-resolution 7T resting-state fMRI dataset from the Human Connectome Project. We used data-driven techniques that relied on spatially-restricted Independent Component Analysis, Dual Regression and linear mixed-effect group-analyses based on participant-specific brain morphology. The results revealed two main activity hotspots inside the hippocampus. The first hotspot was located in an anterior location and was correlated with the somatomotor network. This network was subserved by co-activity in the CA1, CA3, CA4 and Dentate Gyrus fields. In addition, there was an activity hotspot that extended from middle to posterior locations along the hippocampal long-axis and correlated with the default mode network. This network reflected activity in the Subiculum, CA4 and Dentate Gyrus fields. These results show how different sections of the hippocampus participate in two known resting-state networks and how these two resting-state networks depend on different configurations of hippocampal subfield co-activity.Agencia Canaria de Investigación, Innovación y Sociedad de la Información; Ministerio de Ciencia, Innovación y Universidades, Grant/Award Number: PSI2017-84933- P, PSI2017-91955- EXP and TEC2016-80063- C3- 2- R; NIH Blueprint for Neuroscience Research, Grant/Award Number: 1U54MH091657; McDonnell Center for Systems Neuroscience; European Social Fund (ESF

Mediators linking insecure attachment to eating symptoms: A systematic review and meta-analysis

In the last two decades, the number of studies focused on the mediators connecting insecure attachment with Eating Disorders (EDs), at both clinical and sub-clinical level, has considerably increased. However, there has not been a systematic synthesis of this literature to date. To fill this gap, the current meta-analytic review aimed at identifying and quantifying the extent to which mediators contribute to the explanation of this relationship. The present study was registered with PROSPERO (CRD42017076807). A comprehensive search process in seven different electronic databases retrieved 24 studies that examined how insecure attachment leads to ED symptoms through mediation analysis. Standardized regression coefficients of the indirect and total paths of 21 mediation models were pooled. Studies were coded and ranked for quality. We found evidence to show that maladaptive emotion regulation and depressive symptoms had the highest effect size for mediation (mediation ratio [PM] = 0.71). Further, body dissatisfaction, neuroticism, perfectionism, mindfulness and social comparison had significant, but moderate to low mediating effects (PM = 0.21–0.58). The methodological quality of these studies was mostly low to moderate and potential areas for development were highlighted. Our findings support the direct targeting of these psychological constructs in prevention programs and treatment of EDs. Future investigations addressing the time sequence between the variables will provide valuable clues to untangle the prospective contribution of each variable on the development and maintenance of eating pathology.Dr. Takkouche would like to thank the Regional Ministry of Education, Universities and Vocational Training (Consellería de Educación, Universidades y Formación Profesional) (ED431C 2018/20), Santiago de Compostela, SpainS

Interacción entre Salvinia minima y Lemna gibba

Nutrient uptake and competitive ability of the aquatic species Lemna gibba and Salvinia minima were evaluated. The experiment was carried out in a greenhouse and plants were grown as mono-plant cultures and mixed-plant cultures. Three different media were used: tap water and the chemically defined media Lemna and Hutner 1/10. Duration of the experiment was 7 days. Initial and final dry weights and DIN and SRP concentrations were determined. Relative growth rates (RGR) and nutrient uptake rates were calculated. L. gibba´s RGR values increased significantly in Hutner 1/10 medium when types of cultures were analyzed separately. RGR values decreased in Lemna and Hutner 1/10 media in mixed-plant cultures. S. minima did not show significant differences in its RGR values. In mono-plant cultures N and P uptake rates in Lemna medium were significantly larger for L. gibba. In Hutner 1/10 medium P uptake rate was greater for S. minima and N uptake rate was larger for L. gibba. The presence of S. minima negatively affected L. gibba´s growth.Nutrient uptake and competitive ability of the aquatic species Lemna gibba and Salvinia minima were evaluated. The experiment was carried out in a greenhouse and plants were grown as mono-plant cultures and mixed-plant cultures. Three different media were used: tap water and the chemically defined media Lemna and Hutner 1/10. Duration of the experiment was 7 days. Initial and final dry weights and DIN and SRP concentrations were determined. Relative growth rates (RGR) and nutrient uptake rates were calculated. L. gibba´s RGR values increased significantly in Hutner 1/10 medium when types of cultures were analyzed separately. RGR values decreased in Lemna and Hutner 1/10 media in mixed-plant cultures. S. minima did not show significant differences in its RGR values. In mono-plant cultures N and P uptake rates in Lemna medium were significantly larger for L. gibba. In Hutner 1/10 medium P uptake rate was greater for S. minima and N uptake rate was larger for L. gibba. The presence of S. minima negatively affected L. gibba´s growth