Urochloa grass and biofortified maize rotation improve zinc uptake: A promising strategy to fostering human health

Biofortification of crops is a promising strategy for addressing micronutrient deficiencies in populations with limited access to diverse diets. Zinc is a critical trace element for human health, and therefore, more equitable food systems. Zinc deficiency in soil can affect plant growth and yield. The capacity of Urochloa grasses to biologically inhibit nitrification (BNI) and fix nitrogen in the soil, has been shown to improve soil health and crop productivity. In this study, we evaluated the effect of Urochloa grasses subsequently cultivated with maize on the zinc concentration in the grain. We conducted a two-year experiment in 20×20 m plots with nine Urochloa genotypes and a bare soil control, followed by four consecutive cycles of biofortified maize (SGBIOH2). Our results showed an average increase of 9.32 mg/kg of zinc in maize grain compared to the content observed in the control. The genotypes U. humidicola Uh 72 and Urochloa brizantha cv. Marandu showed the highest zinc concentrations during the planting cycles, at 37.29 mg/kg and 36.18 mg/kg, respectively, compared to the average of 25.83 mg/kg in the control treatment. Maize rotation as a subsequent crop of Urochloa grasses had a highly positive effect on zinc concentrations in the grain, enhancing its biofortifying properties. In the soil analysis, high levels of phosphorus were reported, which is inversely related to soil zinc content. Phosphorus is an essential element to produce ATP, the molecule that gives energy to the nitrifying bacteria that carry out nitrification. This may decrease the solubility and mobility of zinc, which in turn affects the nutritional quality of the plants. Brachialactone, an organic compound present in the roots of Urochloa grass, plays an important role in this interaction as it has been scientifically demonstrated that has the potential to inhibit soil microbial activity responsible for nitrification processes. By inhibiting nitrification thanks to the BNI potential of pastures and the root system of a biofortified crop, it is possible to extract and mobilise more zinc from the soil through the roots and plant tissues. Therefore, rotation with Urochloa grasses can be an effective approach to improve the nutritional quality of maize

Mayores concentraciones de Zinc en grano de maíz a través del cultivo en rotación con pastura Urochloa

La rotación de pasturas y maíz biofortificado puede potencialmente mejorar el ciclo de nutrientes y aumentar la capacidad del maíz, como cultivo subsecuente, de absorber y acumular micronutrientes en el grano para el beneficio de la salud humana. Las gramíneas de la especie Urochloa humidicola tienen la capacidad de inhibir el proceso de nitrificación en el suelo (oxidación del amonio a nitrato mediado por microorganismos) y por ende mejorar la disponibilidad del nitrógeno en el suelo. Estudios recientes han demostrado los efectos positivos en el rendimiento de maíz cuando se utiliza en rotación como cultivo subsecuente al cultivo de pastos de Urochloa. En el marco de la iniciativa del OneCGIAR en Ganadería y Clima, se evaluó el efecto de pastos Urochloa sobre la concentración de Zn en el grano de maíz como cultivo subsecuente. Se realizó un experimento de dos años en parcelas de 20 × 20 m con nueve genotipos de Urochloa y un control de suelo desnudo, seguido de cuatro ciclos consecutivos del hibrido de maíz biofortificado (SGBIOH2). Los resultados mostraron un aumento del 36% en el contenido de Zn en el grano en los tratamientos de maíz precedidos de pasturas con un promedio de 35.14 mg/kg versus 25,83 mg/kg observado en el control sin rotación con Urochloa. Es posible que mayor suministro de nitrógeno producto de la inhibición de la nitrificación, haya favorecido la salud de las plantas de maíz mejorando la capacidad para absorber Zn, lo que en última instancia conduciría a una mayor acumulación de Zn en los granos de maíz. Otra posible explicación podría estar en el aumento de la materia orgánica del suelo, promovido por las pasturas, lo cual aumentaría la mineralización en las parcelas con pasto con respecto al control resultando en una mayor solubilización de Zn. Otras variables explicativas al fenómeno observado (i.e., mayor concentración de Zn) están siendo estudiadas tales como cambios en el pH y textura del suelo. Aunque se necesita más investigación en el tema para entender este proceso

Collaborative Research from the Center for Membrane Biosciences

poster abstractThe Center for Membrane Biosciences has been facilitating new research activities between the IUPUI School of Science and IU School of Medicine in the structure, biochemistry, and physiology of biological membranes. Results from two projects resulting from these collaborations are presented. Project 1: Ceramides are sphingolipids involved in the development of lung alveolar cell apoptosis (programmed death) and possibly in the clearance of apoptotic cells by alveolar macrophages. We use a combination of molecular and cellular methods to determine the effect of ceramides on the ability of alveolar macrophages to engulf apoptotic cells. Engulfment experiments of labeled apoptotic Jurkat cells were performed with rat alveolar macrophages (AM) obtained via bronchoalveolar lavage. AM were treated with various ceramide species and efferocytosis was quantified by flow cytometry. Using small-angle X-ray scattering and solid state 2H NMR we determined how ceramides (C6:0, C18:1) affect the molecular organization and the physical properties of model membranes. These studies can lead to a better understanding of the molecular mechanisms responsible for apoptotic cell clearance. If the clearance process is impaired, apoptotic cells may progress to secondary necrosis, resulting in release of harmful cellular contents and tissue inflammation. Project 2: Highly-photostable quantum dots (QD) conjugated to lipids or antibodies can be utilized to explore changes in compartmentalization of the plasma membrane due to hyperinsulinemia using wide field single molecule fluorescence microscopy. Protocols describing the bio-inertness and monovalent binding of QDs to antibodies are outlined, as well as use of confocal fluorescence correlation spectroscopy to determine colloidal stability of CdSe/ZnS QDs in aqueous solution. Tracking experiments on QD-conjugated to transferrin receptors in healthy and insulin-resistant adipocytes detect changes in membrane compartmentalization. The impact of chromium picolinate on receptor mobility was also investigated

Bayesian estimation of agent-based models

We consider Bayesian inference techniques for agent-based (AB) models, as an alternative to simulated minimum distance (SMD). Three computationally heavy steps are involved: (i) simulating the model, (ii) estimating the likelihood and (iii) sampling from the posterior distribution of the parameters. Computational complexity of AB models implies that efficient techniques have to be used with respect to points (ii) and (iii), possibly involving approximations. We first discuss non-parametric (kernel density) estimation of the likelihood, coupled with Markov chain Monte Carlo sampling schemes. We then turn to parametric approximations of the likelihood, which can be derived by observing the distribution of the simulation outcomes around the statistical equilibria, or by assuming a specific form for the distribution of external deviations in the data. Finally, we introduce Approximate Bayesian Computation techniques for likelihood-free estimation. These allow embedding SMD methods in a Bayesian framework, and are particularly suited when robust estimation is needed. These techniques are first tested in a simple price discovery model with one parameter, and then employed to estimate the behavioural macroeconomic model of De Grauwe (2012), with nine unknown parameters