ROLE OF THE HISTONE DEMETHYLASE JMJD3 IN CORTICAL DEVELOPMENT AND NEURAL DIFFERENTIATION

Jmjd3 is a H3K27 demethylase that is required for the neural commitment of ESCs and controls the expression of key drivers and markers of neurulation through the demethylation of H3K27me3. Previous work from our lab has demonstrated that loss of Jmjd3 in mouse embryos causes a complex neurodevelopmental phenotype that results in perinatal death. Such lethality is due to a respiratory failure resulting from the lack of a functional pre-Bo\u308tzinger complex, a small network of neurons that is responsible for respiratory rhythm generation. Rescue experiments performed with catalytically active or inactive Jmjd3 have demonstrated that its demethylase activity is necessary for developing and maintaining the embryonic respiratory neuronal network. This unanticipated finding claims a broader role in brain development for Jmjd3, whose importance extends from early differentiation choices to the late development of neuronal networks. To investigate the effect of Jmjd3 loss on neocortical development, we analyzed Jmjd3 KO embryonic brains at different developmental stages using markers for stem cells and differentiated neurons. We found that loss of Jmjd3 causes a late-onset increase in the number of ventricular zone (VZ) neural precursor cells (NPCs) and a reduction in the cortical neuronal production. Jmjd3 KO VZ NPCs display a higher rate of cell cycle re-entry than their WT counterpart, and have an overall longer cell cycle. In order to pinpoint the mechanism by which Jmjd3 is causally linked to the lengthening of the NPC cell cycle and to the VZ expansion, we investigated the transcriptional effect of Jmjd3 loss by performing RNAseq on mRNA extracted from WT and KO cultured E13.5 primary NPCs. A detailed molecular characterization at the transcriptional level revealed that the phenotype that we observed both in vivo and in vitro in Jmjd3 KO NPCs is linked to supraphysiological activation of the Wnt/B-catenin and Notch pathways, two known regulators of the choice between self- renewal and differentiation in the VZ NPCs of the developing brains, whose upregulation has already been shown to correlate with an increased proliferative potential and hampered neuronal differentiation

Using an on-line image analysis technique to characterize sucrose crystal morphology during a crystallization run

The morphological forms and habits of crystals and agglomeration are important properties on crystallization processes. Online techniques for realtime measurement of these properties are mandatory for a better comprehension of crystal growth phenomenon. The present paper presents and describes a new online method to determine the complexity level of a crystal or a population of crystals during a crystallization process. An image analysis technique is combined with discriminant factorial analysis leading to results that allow the computation of the complexity of crystals through the parameter agglomeration degree of crystals. With this methodology, it has been possible to distinguish online and automatically among three different classes of crystals according to their complexity. It further describes the application of such methodology on the study of CaCl2, D-fructose, and D-glucose influence on the crystallization of sucrose, namely, on crystal size, morphology, and complexity. The effect of supersaturation, growth rate, and impurity concentration on the type, amount, and complexity level of the agglomerates was determined at different temperatures. The combination of image analysis and kinetic results allowed to understand better the crystallization phenomena in the presence and absence of impurities. The image analysis results suggest the possible application of this tool for process control, optimizing, by this way, laboratory and industrial crystallizers.This work was supported by Fundacao para a Ciencia e Tecnologia under program contract numbers SFRH/BD/11315/2002 and SFRH/BPD/45637/2008

Implicazioni di principi teorici e di metodologie sperimentali di crescita sulla cristallizzazione di massa.

In questo capitolo sono inizialmente discussi gli aspetti fondamentali della cristallizzazione da soluzione e fornita una rassegna delle principali teorie di nucleazione e di crescita. Successivamente sono esaminati i meccanismi con cui varie tipologie di impurezze rallentano la velocità di crescita ed alcuni modelli predittivi sono analizzati. Infine sono discusse cinetica e morfologia di crescita di cristalli di saccarosio ottenuti da soluzioni acquose in differenti condizioni, nonché alcune applicazioni alla cristallizzazione in massa sulla base delle considerazioni precedenti

L'equilibrio cristallo-fase madre. Introduzione ai concetti di base e implicazioni sulla crescita.

In questo capitolo è dato particolare risalto agli aspetti termodinamici della cristallizzazione. Sono così analizzati i principali fattori da cui dipendono gli equilibri cristallo/fase madre. E' poi discussa la termodinamica della nucleazione da fasi omogenee o eterogenee. Le forme di equilibrio dei cristalli sono analizzate attraverso l'approccio termodinamico statistico di Stranski-Kaischev e l'approccio strutturale di Hartman e Perdok. Largo spazio è riservato al fenomeno dell'epitassia su substrati omogenei ed eterogenei. Infine è esaminato l'equilibrio di una popolazione di cristalli attraverso il fenomeno del "ripening "di Ostwaldi

Fundamental Aspects of Equilibrium and Crystallization Kinetics.

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Crescita, Adsorbimento e Morfologia di cristalli di saccarosio in soluzioni acquose contenenti raffinosio.

Dall'esame delle isoterme di crescita delle quattro più importanti forme cristallografiche 100, 10-1, 110, -1-10 di cristalli di saccarosio, ottenuti a 40 °C da soluzioni additivate con concentrazioni variabili di Raffinosio, gli autori confermano il drastico rallentamento, fino all'inibizione, delle cinetiche di tutte, tranne l'ultima. Tuttavia il comune andamento parabolico delle isoterme indica la sostanziale conservazione del meccanismo di crescita dislocativo. Il modello previsionale di Kubota-Mullin per le cinetiche di crescita da soluzioni con differenti sovrasaturazioni e concentrazioni di impurezze si è dimostrato soddisfacentemente coerente con i dati sperimentali. Infine i morfodromi (sovrassaturazione, concentrazione Raffinosio) forniscono un'efficace rappresentazione delle morfologie dei cristalli nelle diverse condizioni

Growth of sucrose single crystals from solutions in the presence of raffinose.Experiments and kinetic models.

Raffinose affects the shape of the growth isotherms of the most important flate forms of sucrose crystals obtained from impure solutions , but the (-1-10) one

Automatic Management of Sucrose Cooling Crystallization Based on Near-Infrared Spectroscopy.

The control and correct management of an industrial crystallization process requires the knowledge in real time of some chemico.physical and technological parameters. These often are difficult to evaluate because the process is in continuous evolution. To optimize an industrial crystallization process in order to obtain the best characteristics of both the crystals and the magma, we need to know not only the solubility curve and its variation with the concentration of the impurities, but also: the real-time supersaturation of the solution; the growth kinetics and their variations with the temperature, concentration of impurities and the hydrodynamic conditions of the magma; the surface area of the crystals and its variation during the crystallization process and the morphology of the crystals and their variations with the temperature, supersaturation and the presence of impurities. The correct management of an industrial process is possible if we could know, in real-time, the amount of crystals present in the magma, the ratio between the crystals and the mother liquor, the composition of the mother liquor and, as a consequence, the correct value of the supersaturation and the optimal conditions of the growth kinetics. To obtain all these data and their variations during the crystallization process we tried to utilize the NIR (near infra-red) techinque via a special probe submerged in the growing magma. The first results obtained using this techinque applied to a cooling crystalliztion of pure sucrose are presented and discussed