Benefits of frontal waters for the growth of Engraulis anchoita larvae: The influence of food availability Do Souto, Marina; Spinelli, Mariela Lorena; Brown, Daniel Roberto; Pajaro, Marcelo; Diaz, Marina Vera; Capitanio, Fabiana Lia We studied the abundance, size and growth rates of Engraulis anchoita larvae during the end of the species’ spawning season in relation to environmental variables. Two sampling transects, one in Península Valdés (northern transect: NT) and the other in Isla Escondida (southern transect: ST), with four stations each, were established in late summer. Both locations are characterized by high concentrations of E. anchoita larvae in spring, strongly associated with the presence of frontal waters, at the beginning of the species’ spawning season. Zooplankton and ichthyoplankton were sampled, and temperature profiles and chlorophyll-a satellite images were analyzed for each sampling station. Zooplankton samples were divided in size fractions, and composition and abundances were estimated. Standard length (SL), ontogenetic stages, and abundance (including eggs) were estimated. Additionally, age and growth rates were determined by otolith analysis. Two different scenarios were observed in both transects. In the NT, a frontal structure was found, while at the ST, the water column was completely homogeneous. Total zooplankton abundance was maximum at frontal waters, with 22,195 ind. m−3, being the small size fraction (<200 μm) the most abundant, mainly composed of nauplii (9000 ind. m−3) and cyclopoid copepodites (4000 ind. m−3). The NT showed higher abundance (mean of 126.5 ind. m−2 per station in NT; 29.75 ind. m−2 in ST), faster growth rates of E. anchoita larvae (NT: 0.45 ± 0.04 mm day−1; ST: 0.34 ± 0.09 mm day−1; n = 90), and higher mean SL at frontal waters (7.57 ± 1.52 mm SL) than the ST. In the NT, E. anchoita growth rates were constant in time, whereas in the ST, they decreased with age. Our results support the classical theory, which states that frontal waters provide advantageous environmental conditions for fish larvae feeding, growth and, thus, survival.

Non-aversive photographic measurement method for subcutaneous tumours in nude mice Resasco, Agustina; Carranza Martin, Ana Cristina; Ayala, Miguel Angel; Diaz, Silvina Laura; Carbone, Cecilia We have developed a new method for the measurement of subcutaneous tumour volume which consists in taking photographs of mice in their home cages, to refine the standard method of measurement with calipers. We consider this new method to be non-aversive, as it may be more compatible with mice behavioural preferences and, therefore, improve their welfare. Photographs are captured when mice voluntarily go into an acrylic tube containing graph paper that is later used as a scale. Tumour volumes measured with the caliper and the non-aversive photographic method were compared to those obtained by water displacement volume and weight. Behavioural and physiological changes were evaluated to assess animal welfare. Significant differences were found between measurements obtained with the caliper and the non-aversive photographic method, v. the reference volume acquired by water displacement (P < 0.001). Nevertheless, there was good consistency for these measurements when tumours were measured repeatedly, with all Intra-Class Correlation Coefficients above 0.95. Mice on which the non-aversive photographic method was employed were significantly less reluctant to establish contact with the experimenter (P < 0.001) and behaved less anxiously in a modified-Novelty Suppressed Feeding test. Particularly, statistically significant differences were found in connection with the latency to eat an almond piece (P < 0.05), the frequency of grooming (P < 0.001) and the frequency of defecation (P < 0.001). Corticosterone concentration in faeces and blood glucose were determined and no significant changes were found. Therefore, we propose the non-aversive photographic method to measure subcutaneous tumours as a way to refine methodologies in the field of experimental oncology.

Identification of driver and subclonal mutations in ASXL1 and IDH1/IDH2 genes in an Argentine series of patients with myelofibrosis Scheps, Karen; Meyer, C.; Bestach, Yesica Soledad; Enrico, A.; Bengio, Ruben Guillermo; Rodriguez Zubieta, Mariana; Rivas, M.; de Brasi, Carlos Daniel; Larripa, Irene Beatriz Myelofibrosis (MF) is a Philadelphia-negative myeloproliferative neoplasm (MPN) characterized by clonal proliferation of hematopoietic stem cells, progressive bone marrow fibrosis, abnormal cytokine expression, anemia, splenomegaly, extramedullary hematopoiesis, constitutional symptoms, cachexia, leukemic progression, and shortened survival.1 MF can be diagnosed as a primary myelofibrosis (PMF) disorder or as a complication of the evolution of polycythemia vera (MF post-PV) or essential thrombocythemia (MF post-ET)...

Noncontact AC Voltage Measurements: Error and Noise Analysis Haberman, Marcelo Alejandro; Spinelli, Enrique Mario A capacitive noncontact ac voltage measurement technique and its feasibility to measure arbitrary waveform signals are analyzed. The method provides self-calibration of the scale factor, an important feature considering the high variability that coupling capacitances present. The analysis of several errors related to the technique is performed, showing the impact of different design parameters on the final accuracy. Scaling errors due to the electronic circuit can be constrained to less than 0.5%, and can be disaffected, whereas those due to the frequency dependence of cable sheath permittivity can be up to 3% for polyvinyl chloride sheathed cables. This error is not controllable by electronic design but requires working on electrode probe. A noise model is also proposed and experimentally validated, showing that signal-to-noise ratios of up to 100 dB are achievable with common components. A functional prototype was built and tested by acquiring power-line voltage and other arbitrary signals without contact. Instantaneous voltage signals were acquired by the proposed technique and contrasted with those acquired directly. For the measurement of power-line voltage and using the self-calibration feature, the instantaneous error was lower than 7 V (2.2%) for a ±1300 V measurement range at 50 Hz. If manual correction is applied, the error can be reduced to 0.28 V rms (0.12%)

On two species of Riocypris (Crustacea, ostracoda) from northern Patagonia and their relation to eucypris fontana: Implications in paleoenvironmental reconstructions Coviaga, Corina Anabel; Perez, Alejandra Patricia; Ramos, Lorena Yésica; Alvear, Pablo Andres; Cusminsky, Gabriela Catalina Two species of ostracods new to Patagonia, Argentina, are described. One of them, Riocypris whatleyi sp. nov., is described for the first time, and the second, Riocypris sarsi (Daday, 1902) comb. nov., is reallocated from genus Eucypris to genus Riocypris. Inter-and intra-specific variations in shape, size, and sexual dimorphism were evaluated based on geometric morphometric analysis. Moreover, morphological and morphometric comparative analyses were applied to re-examine living and quaternary specimens recovered from previous studies. Based on these results, a generic reassignment for the Patagonian Eucypris fontana (Jurine, 1820) into the genus Riocypris is proposed. Contributing to the knowledge on the systematic and autecology of this enigmatic species, widely distributed in Patagonia and frequently used in paleolimnological reconstructions, generates science-based evidence for their use as indicator species. Additionally, our results emphasize the usefulness of studying the living representatives (i.e., with valves and appendages) for elucidating the taxonomic status of the individual specimens, especially those present in paleontological records and used as bioproxies in paleolimnological studies.

Efficacy and safety of amantadine for the treatment of L-DOPA-induced dyskinesia Pérez Lloret, Santiago; Rascol, Olivier l-DOPA induced dyskinesias (LIDs) may affect up to 40% of Parkinson’s disease (PD) and impact negatively health-related quality of life. Amantadine has demonstrated significant antidyskinetic effects in animal PD models and in randomized double-blind placebo-controlled trials (RCTs) in patients with PD. These effects are thought to be related to the blockade of NMDA receptors modulating cortico-striatal glutamatergic–dopaminergic interactions involved in the genesis of LIDs. There are three pharmaceutical forms of amantadine currently available in the market: an oral immediate-release (IR) formulation, which is widely available; an extended-release (ER) formulation (ADS-5102) which has been recently developed and approved by the FDA; and an intravenous infusion (IV) solution, which is not commonly used in clinical practice. RCTs with amantadine IR or ER, involving more than 650 patients have shown consistent and long-lasting reductions in LIDs. Interestingly, ADS-5102 not only reduced LIDs, but also reduced significantly at the same time the duration of daily OFF-time, a unique finding compared with other antiparkinsonian medications that usually reduce time spent OFF at the cost of worsening of LIDs. Amantadine IR might also have possible effects on other PD symptoms such as apathy or fatigue. The most common adverse reactions with amantadine are constipation, cardiovascular dysfunction including QT prolongation, orthostatic hypotension and edema, neuropsychiatric symptoms such as hallucinations, confusion and delirium, nausea and livedo reticularis. Corneal degeneration is rare but critical. In summary, amantadine immediate and extended-release are effective and safe for the treatment of LIDs.

Panthera onca (Carnivora, Felidae) in the late Pleistocene-early Holocene of northern Argentina Rodriguez, Sergio Gabriel; Méndez, Cecilia Romina; Soibelzon, Esteban; Soibelzon, Leopoldo Héctor; Contreras, Silvina Andrea; Friedrichs, Juan; Luna, Carlos Alberto; Zurita, Alfredo Eduardo The most northern fossil record of Panthera onca (LINNAEUS, 1758) from Argentina is here reported. The specimen, PVE-F 130, represented by an articulated and well preserved cranium and mandible, atlas and a fragment of left humerus, was exhumed from levels assigned to the Río Bermejo Formation (late Pleistocene-early Holocene; ca. 12.0-9.7 ka), near Villa Escolar, Formosa Province. The associated paleofauna, comprised mostly of large and megafaunal mammals, has a clear taxonomic similarity to that of the Pampean region of Argentina, and suggests open arid to semiarid environments. Indeed, previous analyses of plant remains associated with these vertebrates support the predominance of mega/mesothermal grasslands characterized by C3/C4 grass species.

Spatial segregation and connectivity in young and adult stages of Megaleporinus obtusidens inferred from otolith elemental signatures: Implications for management Avigliano, Esteban; Pisonero, Jorge; Domanico, Alejandro; Silva, Natalia Andrea; Sánchez, Sebastián; Volpedo, Alejandra Boga Megaleporinus obtusidens is a teleost fish of economical and sport importance from Río de la Plata Basin (South America). Otolith core and edge elemental ratios (Ba:Ca, Cu:Ca, Li:Ca, Mg:Ca, Mn:Ca, Pb:Ca, Rb:Ca and Sr:Ca) were compared among three sampling areas from the Río de la Plata Basin (Paraná and Uruguay Rivers and Río de la Plata Estuary) to evaluate the applicability of the fingerprint to study segregation and connectivity in young and adult stages. Several ratios were significantly different among sites for otolith core and edge (p < 0.05). PERMANOVA (p < 0.05) and quadratic discriminant function analysis (classification rates: 86.8% and 82.5% for otolith core and edge, respectively) were found to be highly effective in detecting differences in otolith core and edge fingerprints between sampling sites suggesting the existence of spatial segregation in young and adult life stages, respectively. The presence of relatively isolated groups may require the need to manage the stocks separately.

CLCA2 epigenetic regulation by CTBP1, HDACs, ZEB1, EP300 and miR-196b-5p impacts prostate cancer cell adhesion and EMT in metabolic syndrome disease Porretti, Juliana Carla; Dalton, Guillermo Nicolás; Massillo, Cintia Lorena; Scalise, Georgina Daniela; Farré, Paula Lucía; Elble, Randolph; Gerez, Esther Noemi; Accialini, Paula Lucia; Cabanillas, Ana Maria de Los A.; Gardner, Kevin; de Luca, Paola; de Siervi, Adriana Prostate cancer (PCa) is the most common cancer among men. Metabolic syndrome (MeS) is associated with increased PCa aggressiveness and recurrence. Previously, we proposed C-terminal binding protein 1 (CTBP1), a transcriptional co-repressor, as a molecular link between these two conditions. Notably, CTBP1 depletion decreased PCa growth in MeS mice. The aim of this study was to investigate the molecular mechanisms that explain the link between MeS and PCa mediated by CTBP1. We found that CTBP1 repressed chloride channel accessory 2 (CLCA2) expression in prostate xenografts developed in MeS animals. CTBP1 bound to CLCA2 promoter and repressed its transcription and promoter activity in PCa cell lines. Furthermore, we found that CTBP1 formed a repressor complex with ZEB1, EP300 and HDACs that modulates the CLCA2 promoter activity. CLCA2 promoted PCa cell adhesion inhibiting epithelial–mesenchymal transition (EMT) and activating CTNNB1 together with epithelial marker (CDH1) induction, and mesenchymal markers (SNAI2 and TWIST1) repression. Moreover, CLCA2 depletion in PCa cells injected subcutaneously in MeS mice increased the circulating tumor cells foci compared to control. A microRNA (miRNA) expression microarray from PCa xenografts developed in MeS mice, showed 21 miRNAs modulated by CTBP1 involved in angiogenesis, extracellular matrix organization, focal adhesion and adherents junctions, among others. We found that miR-196b-5p directly targets CLCA2 by cloning CLCA2 3′UTR and performing reporter assays. Altogether, we identified a new molecular mechanism to explain PCa and MeS link based on CLCA2 repression by CTBP1 and miR-196b-5p molecules that might act as key factors in the progression onset of this disease.

Spatial and temporal plant-to-plant variability effects on soybean yield Masino, Alejandra; Rugeroni, Pablo; Borras, Lucas; Rotundo, José Luis Plant density and row spacing are management practices that farmers use to maximize soybean (Glycine max (L.) Merr.) yield. Other canopy aspects related to seedling establishment like spatial (spacing among plants) and temporal (timing of plant emergence) within-row plant-to-plant variability have received less attention. Negative yield effects of non-uniform stands have been reported for maize (Zea mays subsp. Mays L.), but it is commonly accepted that soybean plants compensate for any plant-to-plant growth difference. Planting quality is becoming relevant because small yield effects can have a high economic return due to high soybean prices and low implementation costs. The objectives were to assess the impact of non-uniform spatial and temporal seedling establishment on soybean yields and to identify putative mechanisms. Results showed that, across planting dates and plant densities, there was no yield loss due to increased spatial plant-to-plant variation in a later maturity group cultivar (MG IV), but reduced yield in an earlier one (MG III). Contrarily, non-uniform temporal distributions significantly reduced yield across cultivars. Having a poor spatial distribution had no effect on the average plant growth rate or its plant-to-plant variability. A poor temporal distribution did not affect individual average plant growth rate but variability was increased. This increased variability determined that some individuals had higher plant growth but reduced seed number because of reduced reproductive partitioning. Novel findings can be summarized as: (i) the higher relative importance of temporal vs. spatial non-uniform canopies in determining soybean yield reductions, (ii) the influence of reduced seed set at higher plant growth rates to mechanistically explain yield reductions in non-uniform temporal canopies; (iii) the concept that the yield effect of non-uniform temporal canopies cannot be overcome by increased plant densities. Future research needs to better understand the interactions between cultivar reproductive characteristics and susceptibility to non-uniform temporal canopies.

Molecular confirmation of the linkage between the rhizopus oryzae CYP51A gene coding region and its intrinsic voriconazole and fluconazole resistance Macedo, Daiana; Leonardelli, Florencia; Dudiuk, Catiana Beatriz; Theill, Laura; Cabeza, Matías Sebastián; Gamarra, Soledad; Garcia, Guillermo Manuel Rhizopus oryzae is the most prevalent causative agent of mucormycosis, an increasingly reported opportunistic fungal infection. These Mucorales are intrinsically resistant to Candida- and Aspergillus-active antifungal azole drugs, such as fluconazole (FLC) and voriconazole, respectively. Despite its importance, the molecular mechanisms of its intrinsic azole resistance have not been elucidated yet. The aim of this work was to establish if the Rhizopus oryzae CYP51 genes are uniquely responsible for intrinsic voriconazole and fluconazole resistance in these fungal pathogens. Two CYP51 genes were identified in the R. oryzae genome. We classified them as CYP51A and CYP51B based on their sequence similarity with other known fungal CYP51 genes. Later, we obtained a chimeric Aspergillus fumigatus strain harboring a functional R. oryzae CYP51A gene expressed under the regulation of the wild-type A. fumigatus CYP51A promoter and terminator. The mutant was selected after transformation by using a novel procedure taking advantage of the FLC hypersusceptibility of the A. fumigatus CYP51A deletion mutant used as the recipient strain. The azole susceptibility patterns of the A. fumigatus transformants harboring R. oryzae CYP51A mimicked exactly the azole susceptibility patterns of this mucormycete. The data presented in this work demonstrate that the R. oryzae CYP51A coding sequence is uniquely responsible for the R. oryzae azole susceptibility patterns.

El concepto de capitalismo en la perspectiva pragmática de Boltanski y Chiapello; The Concept of Capitalism in Boltanski and Chiapello’s Pragmatic Perspective Gonnet, Juan Pablo; Abril, Francisco Manuel En el presente trabajo proponemos un análisis crítico de la conceptualización del capitalismo ofrecida por la perspectiva pragmática de Boltanski y Chiapello en su libro El nuevo espíritu del capitalismo. Para estos autores el capitalismo es la exigencia de acumulación ilimitada de capital que se legitima mediante justificaciones morales, reconociéndose un vínculo ineludible entre el capitalismo y la moral. Nuestro objetivo es mostrar que el mismo es interpretado de modos variables, ambiguos y contradictorios, lo que genera una teorización imprecisa en torno al capitalismo y a los aportes que la corriente sociológica del pragmatismo podría brindar para su comprensión.; This article critically examines the pragmatic conceptualization of capitalism offered in Boltanski and Chiapello’s book El nuevo espíritu del capitalismo (The New Spirit of Capitalism). For them, capitalism is the demand for unlimited accumulation of capital legitimized through moral justifications, thus recognizing an unavoidable link between capitalism and morality. The article’s authors aim to show that this is interpreted in different ways that are both ambiguous and contradictory, thus generating an imprecise theorization of capitalism and the contributions that the pragmatist sociological current can offer for understanding it.

¿Centros o cuerpos de delegados?: Las luchas estudiantiles de los años setenta frente al debate acerca de las formas organizativas. El caso de la UBA; Student centers or bodies o delegates?: The student struggles of the seventy years against the debate about the organizational forms. The case of the UBA Califa, Juan Sebastián En este trabajo se dará cuenta de las pujas generadas a comienzos de los años setenta en el movimiento estudiantil argentino en lo concerniente a los principios organizativos más eficaces para derrotar a la dictadura imperante. Mientras que el reformismo bregaba por reconstruir los centros de estudiantes, otras organizaciones de izquierda y en menor medida peronistas se orientaban a fortalecer los cuerpos de delegados por curso. Los avatares de esta competencia, con sus ganadores y perdedores, permite adentrarse en un período clave de la universidad argentina, revisitando así el debate acerca de la vigencia del reformismo como identidad programática entre sus capas más jóvenes. Este artículo, se adentrará en lo acaecido en la Universidad de Buenos Aires (UBA), acudiendo a fuentes y bibliografía variadas.; In this paper, we will see the bids generated in the early seventies in the Argentine student movement regarding the most effective organizing principles to defeat the ruling dictatorship. While reformism struggled to rebuild student centers, other organizations of the left and, to a lesser extent, Peronists aimed to strengthen the bodies of delegates per course. The ups and downs of this competition, with its winners and losers, allows us to enter a key period of the Argentine university, revisiting the debate about the validity of reformism as a programmatic identity among its younger layers. This article will delve into what happened at the University of Buenos Aires (UBA), going to sources and bibliography varied.

Categorías espaciales y dicotomías jerárquicas en la definición de la santidad femenina de María Egipciaca; Spatial Categories and Hierarchical Dichotomies in the Definition of the Female Sanctity of Mary of Egypt Zubillaga, Carina Alejandra En la "Vida de Santa María Egipciaca", poema hispánico de la primera mitad del siglo XIII transmitido por el códice K-III-4 de la Biblioteca de San Lorenzo de El Escorial del siglo XIV, las categorías espaciales exterior-interior, margen-centro, bajo-alto permiten ahondar en la santidad femenina del período como práctica social, a partir de la configuración de la leyenda de esta figura paradigmática de las prostitutas arrepentidas. En el presente artículo, se ponen de relieve los espacios comunitarios del templo y el monasterio frente al espaciodesolado del desierto, representativo de una de las variantes de la marginalidad de la espiritualidad femenina en el Medioevo.

Interaction of gabaergic ketones with model membranes: A molecular dynamics and experimental approach Miguel, Virginia; Sánchez, Mariela Eugenia; Garcia, Daniel Asmed γ-Aminobutyric-acid receptor (GABA A -R), a membrane intrinsic protein, is activated by GABA and modulated by a wide variety of recognized drugs. GABA A -R is also target for several insecticides which act by recognition of a non-competitive blocking site. Mentha oil is rich in several ketones with established activity against various insects/pests. Considering that mint ketones are highly lipophilic, their action mechanism could involve, at least in part, a non-specific receptor modulation by interacting with the surrounding lipids. In the present work, we studied in detail the effect on membranes of five cyclic ketones present in mint plants, with demonstrated insecticide and gabaergic activity. Particularly, we have explored their effect on the organization and dynamics of the membrane, by using Molecular Dynamics (MD) Simulation studies in a bilayer model of DPPC. We performed free diffusion MD and obtained spatially resolved free energy profiles of ketones partition into bilayers based on umbrella sampling. The most favored location of ketones in the membrane corresponded to the lower region of the carbonyl groups. Both hydrocarbon chains were slightly affected by the presence of ketones, presenting an ordering effect for the methylene groups closer to the carbonyl. MD simulations results were also contrasted with experimental data from fluorescence anisotropy studies which evaluate changes in membrane fluidity. In agreement, these assays indicated that the presence of ketones between lipid molecules induced an enhancement of the intermolecular interaction, increasing the molecular order throughout the bilayer thickness.

Beta-Glucan and Phenolic Compounds: Their Concentration and Behavior during in Vitro Gastrointestinal Digestion and Colonic Fermentation of Different Barley-Based Food Products Mosse, Juana Inés; Motilva, Maria José; Ludwig, Iziar A. Among cereals, barley (Hordeum vulgare L.) is notable for its high content of bioactives such as β-glucan and phenolic compounds, but it is not used as widely in human nutrition as wheat. To compare the impact of food formulation and processing on barley bioactives, crackers, cookies, and fresh pasta were prepared combining wheat and barley flour. After quantification of β-glucan and PCs in the barley flour and barley-based products, their behavior during in vitro gastrointestinal digestion and colonic fermentation was studied. The β-glucan and PCs were not drastically affected by processing. The amount of bioaccessible compounds after gastrointestinal digestion was lower than the amount retained in the undigested fraction. After in vitro colonic fermentation, β-glucan was mainly metabolized to acetic and propionic acids and PCs to phenylpropionic and phenylacetic acids. Based on the results of the study, the daily ingestion of barley-based foods may contribute to the intake of beneficial bioactive compounds.

Natural products to control biofilm on painted surfaces Bogdan, Sofia Tamara; Deya, Marta Cecilia; Micheloni, Oscar Bernardo; Bellotti, Natalia; Romagnoli, Roberto This paper aims to study five vegetables extracts as possible additives to control bacterial growth on indoor water-borne paints. The extracts were obtained from the weeds Raphanus sativus, Rapistrum rugosum, Sinapis arvensis, Nicotiana longiflora and Dipsacus fullonum, used in traditional medicine as antimicrobial compounds.As a general rule, results showed that tested paints were efficient in inhibitingbiofilm formation, specially that formulated with Nicotiana longiflora.The tested paints can be used to protect walls from microbial colonizationwhich shortened coatings useful life by discoloration and/or degradation.Concomitantly, indoor microbial colonization by aerosols could be alsodiminished. This is especially important in places that should have highstandards of environmental hygiene as in the food industry, health-care andsanitary centers, etc.

CO preferential oxidation on cordierite monoliths coated with CuO-CeO2/SBA-15 catalysts. Further insights into the physico-chemical aspects of the catalytic behavior Lacoste, Albano Mauricio; Tiscornia, Ines Silvia; Boix, Alicia Viviana CuO-CeO2/SBA-15 catalysts deposited over cordierite monoliths were prepared to be tested in CO preferential oxidation (COPrOx). The influence of molar ratio between the CuO and CeO2 active phases, their concentration, and the incorporation method into the mesoporous structure were analyzed. Powder catalysts were also studied in order to select the best formulations to coat the monolith walls. Four CuO/CeO2 molar ratios over SBA-15 were obtained by incipient wetness impregnation technique (successive impregnation and co-impregnation). The CuO/CeO2 = 0.55 ratio powder catalyst showed the best CO conversion in the temperature range studied, reaching 100% at 160 °C. The incorporation of active phases into the structured support produced similar or better catalytic behaviors. The addition of 10% CO2 slightly decreased the CO conversion, while the addition of 10% H2O partially deactivated the catalyst. The structured and powder catalysts prepared were characterized by N2 sorption, TEM, SEM, XRD, XPS and TPR in order to identify and relate their physico-chemical properties with the catalytic behavior.

Optimal design of dynamic experiments in the development of cybernetic models for bioreactors Luna, Martín Francisco; Martínez, Ernesto Carlos Cybernetic models of bioreactors are appealing due to their capacity to account for regulatory mechanisms in cell metabolism by modeling the synthesis of enzymes and their activities. For a given objective of interest, experimental data used to fit the cybernetic model parameters should be maximally informative. To excite purposefully the most relevant metabolic pathways, a dynamic experiment is designed by accounting for the sensitivity of the chosen objective to time-varying operating conditions. In this work, the bioreactor feeding profile and sampling times are designed to maximize the information content. A Bayesian optimization approach is proposed to solve the resulting mathematical program. As a case study, biomass production is used as the objective to be maximized in fed-batch cultivation of Saccharomyces cerevisiae growing on glucose as a carbon source. Experimental results demonstrate that the proposed approach helps to iteratively improve a cybernetic model by designing experiments that maximize the information content.

Effects of nutrient enrichment and grazing by an invasive filter feeder on phytoplankton biomass in a South West Atlantic coastal lagoon Bruschetti, Carlos Martin; Addino, Mariana del Sol; Luppi, Tomas Atilio; Iribarne, Oscar Osvaldo Invasive species can exert strong effects on structure and function of marine ecosystem. In estuaries, nutrient enhancement due to anthropogenic activities can increase microalgal biomass but invading filter-feeders can eventually regulate their abundance. This is what we hypothesized that is happening in a SW Atlantic coastal lagoon (Mar Chiquita, 37°40′S, 57°23′W, Argentina) invaded by the polychaete Ficopomatus enigmaticus. Here, we experimentally evaluated this hypothesis in a mesocosms experiment. Four treatments were performed: (T1) with nutrients (NO3, PO4 and NH4), (T2) with reefs and nutrients, (T3) with reefs, and (T4) without reefs or nutrients. Water samples were obtained to determine in vivo chlorophyll a (Chla) and nutrients concentration. Additionally, to evaluate the trophic position and particle selectivity by the polychaete, analysis of stable isotopes of particulate organic matter (POM) of the water and individuals were performed. Stable isotopes analysis showed that the main resource used by F. enigmaticus was the fraction of POM between 62 and 250 µm, showing particle selectivity and suggesting that the reefs have the potential to promote shifts in size, composition and biomass of local food source. Mesocosms experiments showed that nutrient supply increased the Chla concentration, but when reefs were added, the Chla decreased. Thus, nutrients increased the phytoplankton biomass but grazing by the reefs counteracted these increments. This indicates that an invader such as F. enigmaticus might modulate an anthropogenic impact via suspension feeding, and therefore its role in mitigate the consequences of eutrophication may be highly important.