GABAergic presubicular projections to the medial entorhinal cortex of the rat

We characterized presubicular neurons giving rise to bilateral projections to the medial entorhinal cortex (MEA) of the rat. Retrograde labeling of presubiculo–entorhinal projections with horseradish peroxidase and subsequent GABA immunocytochemistry revealed that 20–30 % of the ipsilaterally projecting neurons are GABAergic. No GABAergic projections to the contralateral MEA were observed. GABAergic projection neurons were observed only in the dorsal part of the presubiculum, which, when taking into account the topography of presubicular projections to MEA, indicates that only the dorsal part of MEA receives GABAergic input. The GABAergic projection neurons constitute �30-40 % of all GABAergic neurons present in the superficial layers of the dorsal presubiculum. Using doublelabel fluorescent retrograde tracing, we found that the ipsilateral and contralateral presubiculo–entorhinal projections originat

What Does the Anatomical Organization of the Entorhinal Cortex Tell Us?

The entorhinal cortex is commonly perceived as a major input and output structure of the hippocampal formation, entertaining the role of the nodal point of cortico-hippocampal circuits. Superficial layers receive convergent cortical information, which is relayed to structures in the hippocampus, and hippocampal output reaches deep layers of entorhinal cortex, that project back to the cortex. The finding of the grid cells in all layers and reports on interactions between deep and superficial layers indicate that this rather simplistic perception may be at fault. Therefore, an integrative approach on the entorhinal cortex, that takes into account recent additions to our knowledge database on entorhinal connectivity, is timely. We argue that layers in entorhinal cortex show different functional characteristics most likely not on the basis of strikingly different inputs or outputs, but much more likely on the basis of differences in intrinsic organization, combined with very specific sets of inputs. Here, we aim to summarize recent anatomical data supporting the notion that the traditional description of the entorhinal cortex as a layered input-output structure for the hippocampal formation does not give the deserved credit to what this structure might be contributing to the overall functions of cortico-hippocampal networks

Coexpression of vesicular glutamate transporters 1 and 2, glutamic acid decarboxylase and calretinin in rat entorhinal cortex

We studied the distribution and coexpression of vesicular glutamate transporters (VGluT1, VGluT2), glutamic acid decarboxylase (GAD) and calretinin (CR, calcium-binding protein) in rat entorhinal cortex, using immunofluorescence staining and multichannel confocal laser scanning microscopy. Images were computer processed and subjected to automated 3D object recognition, colocalization analysis and 3D reconstruction. Since the VGluTs (in contrast to CR and GAD) occurred in fibers and axon terminals only, we focused our attention on these neuronal processes. An intense, punctate VGluT1-staining occurred everywhere in the entorhinal cortex. Our computer program resolved these punctae as small 3D objects. Also VGluT2 showed a punctate immunostaining pattern, yet with half the number of 3D objects per tissue volume compared with VGluT1, and with statistically significantly larger 3D objects. Both VGluTs were distributed homogeneously across cortical layers, with in MEA VGluT1 slightly more densely distributed than in LEA. The distribution pattern and the size distribution of GAD 3D objects resembled that of VGluT2. CR-immunopositive fibers were abundant in all cortical layers. In double-stained sections we noted ample colocalization of CR and VGluT2, whereas coexpression of CR and VGluT1 was nearly absent. Also in triple-staining experiments (VGluT2, GAD and CR combined) we noted coexpression of VGluT2 and CR and, in addition, frequent coexpression of GAD and CR. Modest colocalization occurred of VGluT2 and GAD, and incidental colocalization of all three markers. We conclude that the CR-containing axon terminals in the entorhinal cortex belong to at least two subpopulations of CR-neurons: a glutamatergic excitatory and a GABAergic inhibitory

Use of peroxidase substrate Vector VIP for multiple staining in light microscop

The study of the distribution of a fiber input to a particular brain area and the visualization of the anatomical relationships of that input with both projection- and interneurons, requires a triple-staining that allows the unequivocal distinction of each of the three components in one and the same histological section. In this regard, we investigated the properties of a recently introduced peroxidase chromogen, VIP (V-VIP; Vector Labs) in combination with two traditional substrates, standard diaminobenzidine (DAB, brown precipitate) and nickel-enhanced DAB (DAB-Ni, black). In rats, the anterograde tracer biotinylated dextran amine (BDA) and the retrograde tracer fluorogold (FG) were injected in the perirhinal cortex and hippocampus, respectively. Transported BDA was detected with an avidin-biotin-peroxidase complex, whereas the transported FG was detected via a PAP method. Tracing with BDA and FG was combined with parvalbumin- or calbindin-immunocytochemistry. We compared various combinations and staining sequences. The best results were obtained with a staining sequence comprising first the BDA stain with DAB-Ni as chromogen, second the FG protocol with the chromogen DAB and finally, parvalbumin- or calbinding-immunocytochemistry using the chromogen V-VIP. The order with which the chromogens were applied appeared to be critical. Partial or even total loss of V-VIP reaction product has been observed after standard dehydration in ethanol. As an alternative, a quick dehydration procedure in toluene yields much better staining. Colour separation is excellent and the sensitivity is high. This procedure may also be used for detection of any other combination of three different labels, taking the usual care to avoid cross-reactivity between antibodies

Multiple axonal tracing: simultaneous detection of three tracers in the same section

Multiple neuroanatomical tract-tracing methods are important tools for elucidating the connectivity between different populations of neurons. Evaluation of the question as to whether two specific fiber inputs converge on a particular, identified population of projection neurons requires the application of a triple-staining procedure that allows the unequivocal detection of three markers in a single section. The present report deals with a combination of tracing methods using anterogradely transported Phaseolus vulgaris leucoagglutinin and biotinylated dextran amine in conjunction with retrogradely transported Fluoro-Gold. These tracers were simultaneously detected according to a three-color paradigm, which includes the use of three different peroxidase substrates (nickel-enhanced diaminobenzidine, diaminobenzidine, and Vector VIP), thus resulting in three distinct precipitates: black, brown, and purple. We illustrate this method by showing convergence of projections arising from neurons located in two separate basal ganglia-related nuclei onto identified thalamostriatal projection neurons

Complex brain circuits studied via simultaneous and permanent detection of three transported neuroanatomical tracers in the same histological section.

Experimental neuroanatomical tracing methods lie at the basis of the study of the nervous system. When the scientific question is relatively straightforward, it may be sufficient to derive satisfactory answers from experiments in which a single neuroanatomical tracing method is applied. In various scientific paradigms however, for instance when the degree of convergence of two different projections on a particular cortical area or subcortical nucleus is the subject of study, the application of single tracing methods can be either insufficient or uneconomical to solve the questions asked. In cases where chains of projections are the subjects of study, the simultaneous application of two tracing methods or even more may be compulsory. The present contribution focuses on combinations of several neuroanatomical tract-tracing strategies, enabling in the end the simultaneous, unambiguous and permanent detection of three transported markers according to a three-color paradigm. A number of combinations of three tracers or of two tracers plus the immunocytochemical detection of a neuroactive substance can be conceived; we describe several of these combinations implemented by us using the present multitracer protocol

Evaluación de híbridos de girasol en el departamento La Paz (Ciclo agrícola 2021/22)

El departamento La Paz registró para el ciclo agrícola 2020/21 el 43 % del área sembrada con girasol y el 46 % de la producción (BOLSACER, 2022), siendo el departamento de mayor área sembrada en la provincia de Entre Ríos con girasol. El mismo se encuentra distante de las principales áreas de producción de girasol (Parodi et al., 2020) fuente de generación de la tecnología de manejo del cultivo motivo por el cual se hace necesario generar información local. Una de las principales decisiones de manejo es la selección del híbrido en función de la evaluación del comportamiento productivo, sanitario y de calidad de los mismos. En este sentido productores y técnicos deberían realizar la elección de los cultivares en función de maximizar el uso de recursos y minimizar impactos ambientales negativos (Zuil, 2019). Actualmente, una de las principales limitantes detectadas, es la dificultad de contar con datos comparativos en la provincia de los genotipos nuevos lanzados al mercado. El objetivo del presente trabajo fue comparar el rendimiento de distintos híbridos disponibles comercialmente adaptados para la zona.EEA ParanáFil: Behr, Enrique Federico. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Paraná. Agencia de Extensión Rural Crespo; ArgentinaFil: Boffa, Susana Bertilde. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Paraná. Agencia de Extensión Rural La Paz; ArgentinaFil: Pautasso, Juan Manuel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Paraná. Agencia de Extensión Rural Diamante; ArgentinaFil: Kahl, Mirta Beatriz. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Paraná. Agencia de Extensión Rural Crespo; ArgentinaFil: Wouterlood, Natalia. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Paraná. Agencia de Extensión Rural La Paz; Argentin

Evaluación de híbridos de maíz en red de las Agencias Extensión Rural del INTA EEA Paraná (Ciclo agrícola 2021/22)

El presente trabajo resume la experiencia realizada por las Agencias de Extensión del INTA EEA Paraná, atendiendo la demanda de semilleros y productores en búsqueda de información local sobre el comportamiento de los principales híbridos de maíz disponibles en el mercado por su potencial de rendimiento en distintos ambientes productivos con manejo de productor. Se determinaron diferencias significativas de rendimientos según sitio y según híbridos, pero el ordenamiento productivo de los híbridos fue similar en cada sitio.EEA ParanáFil: Pautasso, Juan Manuel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Paraná. Agencia de Extensión Rural Diamante; ArgentinaFil: Kahl, Mirta Beatriz. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Paraná. Agencia de Extensión Rural Crespo; ArgentinaFil: Vallejos, Maximiliano. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Paraná. Agencia de Extensión Rural Victoria; ArgentinaFil: Brassesco, Raul Francisco. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Paraná. Agencia de Extensión Rural Victoria; ArgentinaFil: Maydana, Haydeé Cristina. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Paraná. Agencia de Extensión Rural Nogoya; ArgentinaFil: Boffa, Susana Bertilde. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Paraná. Agencia de Extensión Rural La Paz; ArgentinaFil: Wouterlood, Natalia. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Paraná. Agencia de Extensión Rural La Paz; ArgentinaFil: Behr, Enrique Federico. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Paraná. Agencia de Extensión Rural Crespo; Argentin

Evaluación de cultivares de trigo en red de las agencias de la EEA Paraná (Ciclo agrícola 2021-22)

El presente trabajo evalúa el comportamiento de cultivares desarrollados en INTA y disponibles en el mercado, en lotes de productores ubicados en diferentes ambientes productivos de la provincia, en el área de influencia de la EEA Paraná.EEA ParanáFil: Pautasso, Juan Manuel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Paraná. Agencia de Extensión Rural Diamante; Argentina.Fil: Maydana, Haydeé Cristina. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Paraná. Agencia de Extensión Rural Nogoyá; ArgentinaFil: Boffa, Susana Bertilde. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Paraná. Agencia de Extensión Rural La Paz; ArgentinaFil: Wouterlood, Natalia. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Paraná. Agencia de Extensión Rural La Paz; ArgentinaFil: Kahl, Mirta Beatriz. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Paraná. Agencia de Extensión Rural Crespo; ArgentinaFil: Gallardo, Maricel Andrea. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Paraná. Departamento Mejoramiento; ArgentinaFil: Gieco, Lucrecia Cristina. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Paraná. Departamento Mejoramiento; Argentina.Fil: Behr, Enrique Federico. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Paraná. Agencia de Extensión Rural Crespo; Argentin