Proline dehydrogenase regulates redox state and respiratory metabolism in Trypanosoma Cruzi

Over the past three decades, L-proline has become recognized as an important metabolite for trypanosomatids. It is involved in a number of key processes, including energy metabolism, resistance to oxidative and nutritional stress and osmoregulation. In addition, this amino acid supports critical parasite life cycle processes by acting as an energy source, thus enabling host-cell invasion by the parasite and subsequent parasite differentiation. In this paper, we demonstrate that L-proline is oxidized to Δ(1)-pyrroline-5-carboxylate (P5C) by the enzyme proline dehydrogenase (TcPRODH, E.C. 1.5.99.8) localized in Trypanosoma cruzi mitochondria. When expressed in its active form in Escherichia coli, TcPRODH exhibits a Km of 16.58±1.69 µM and a Vmax of 66±2 nmol/min mg. Furthermore, we demonstrate that TcPRODH is a FAD-dependent dimeric state protein. TcPRODH mRNA and protein expression are strongly upregulated in the intracellular epimastigote, a stage which requires an external supply of proline. In addition, when Saccharomyces cerevisiae null mutants for this gene (PUT1) were complemented with the TcPRODH gene, diminished free intracellular proline levels and an enhanced sensitivity to oxidative stress in comparison to the null mutant were observed, supporting the hypothesis that free proline accumulation constitutes a defense against oxidative imbalance. Finally, we show that proline oxidation increases cytochrome c oxidase activity in mitochondrial vesicles. Overall, these results demonstrate that TcPRODH is involved in proline-dependant cytoprotection during periods of oxidative imbalance and also shed light on the participation of proline in energy metabolism, which drives critical processes of the T. cruzi life cycle.

The gender wage gap in developing and transition countries

The aim of my dissertation is to study the gender wage gap with a specific focus on developing and transition countries. In the first chapter I present the main existing theories proposed to analyse the gender wage gap and I review the empirical literature on the gender wage gap in developing and transition countries and its main findings. Then, I discuss the overall empirical issues related to the estimation of the gender wage gap and the issues specific to developing and transition countries. The second chapter is an empirical analysis of the gender wage gap in a developing countries, the Union of Comoros, using data from the multidimensional household budget survey “Enquete integrale auprès des ménages” (EIM) run in 2004. The interest of my work is to provide a benchmark analysis for further studies on the situation of women in the Comorian labour market and to contribute to the literature on gender wage gap in Africa by making available more information on the dynamics and mechanism of the gender wage gap, given the limited interest on the topic in this area of the world. The third chapter is an applied analysis of the gender wage gap in a transition country, Poland, using data from the Labour Force Survey (LSF) collected for the years 1994 and 2004. I provide a detailed examination of how gender earning differentials have changed over the period starting from 1994 to a more advanced transition phase in 2004, when market elements have become much more important in the functioning of the Polish economy than in the earlier phase. The main contribution of my dissertation is the application of the econometrical methodology that I describe in the beginning of the second chapter. First, I run a preliminary OLS and quantile regression analysis to estimate and describe the raw and conditional wage gaps along the distribution. Second, I estimate quantile regressions separately for males and females, in order to allow for different rewards to characteristics. Third, I proceed to decompose the raw wage gap estimated at the mean through the Oaxaca-Blinder (1973) procedure. In the second chapter I run a two-steps Heckman procedure by estimating a model of participation in the labour market which shows a significant selection bias for females. Forth, I apply the Machado-Mata (2005) techniques to extend the decomposition analysis at all points of the distribution. In Poland I can also implement the Juhn, Murphy and Pierce (1991) decomposition over the period 1994-2004, to account for effects to the pay gap due to changes in overall wage dispersion beyond Oaxaca’s standard decomposition.

Tris(trimethylsilyl)silyl substituted alkali- and transition metal guaiazulenides

In der vorliegenden Arbeit wird ein prochirales, aus natürlichen Resourcen gewonnenes Azulen, das Guajazulen genutzt, um neuartige chirale Cyclopentadienyl-Systeme aufzubauen. Mit Alkalimetallhypersilaniden als starke und sperrige Nukleophile gelingt es hypersilylsubstituierte Gujazulenide zu synthetisieren. Diese wurden mittels Elementaranalyse, NMR-Spektroskopie und Röntgendiffraktometrie charakterisiert. Durch nachfolgende Metathesen mit Übergangsmetallhalogeniden konnten in vielen Fällen die entsprechenden Metallocene erhalten werden. Die Experimente enthüllen eine ausgeprägte Regioselektivität der Addition des sperrigen Hypersilyanions an das Guajazulen, die durch das eingesetzte Lösungsmittel graduell verändert werden kann. In nicht-koordinierenden Lösungsmitteln findet man ausschließlich eine Addition an der 6-Position, die 6-Hypersilyl-2,6-dihydroguajazulenide (6-Hyp-Hgual) (M=Li 1, K 2, Cs 4) in ausgezeichneten Ausbeuten liefert. In polaren Solventien erhält man hingegen Mischungen der 6- und 8-Regioisomeren: 2 bzw. (8-Hyp-Hgual) (3). 2 bleibt aber hierbei das Hauptprodukt. Röntgenbeugungsexperimente zeigen, dass 1 im Kristall als dimerer Sandwich-Komplex, meso-[Li2(6-Hyp-Hgual)2], und die THF-Solvate (thf)4K(6-Hyp-Hgual) (2a) sowie (thf)4K(8-Hyp-Hgual) (3a) jeweils als Halb-Sandwich-Komplexe in einer racemischen Mischung vorliegen. Die Verbindungen 1, 2, 3 and 4 eignen sich sehr gut dazu, in Metathesereaktionen als Precursor für neuartige chirale Metallozen-Komplexe eingesetzt zu werden. Insbesondere das Kaliumderivat 2 besticht durch die einfache und relativ preiswerte Synthese, die erzielten hohen Ausbeuten (>80%) und seine leichte Handhabbarkeit. In THF als Solvent wurden die Metallocene 5:5-M’(6-Hyp-Hgual)2 (M’ = Mn 5, Fe 6, Ni 8) und 5:5-Fe(8-Hyp-Hgual)2 (7) erhalten. Bei Verwendung einiger redox-aktiver Metallhalogenide beobachtet man jedoch die Zersetzung der Metallocene unter Bildung des oxidativen Kopplungsproduktes (3-Hyp-6-Hgual)2 (9) sowie der Ausscheidung von Metall. Die Umsetzung von Halogeniden der Gruppe 4 (TiCl3 and M’’Cl4 (M’’ = Ti, Zr, Hf)) mit 2 liefert in THF ausschließlich die Metallozendichloride M’’(6-Hyp-Hgual)2Cl2 (M’’ = Ti (10), Zr (11), Hf (12)). Die erhaltenen Metallozenderivate fallen als Diastereomeren-Gemische an, die sich durch fraktionierende Kristallisation teilweise oder vollständig in ihre Bestandteile, das jeweilige R,R-Racemat und das R,S-meso-Diastereomer auftrennen lassen. Die Strukturen der rac-Diastereomere konnten durch Beugungsexperimente aufgeklärt werden. Durch eine Metathese von 2 mit Hyp-Cl kann eine zweite Hypersilylgruppe in die 2-Position des Guajazulen-Gerüstes eingeführt werden. Das entstehende 2,6-bis(Hyp)-H2gua (14) kann anschließend mit nBuLi in das extrem luft- und feuchtigkeitsempfindliche Li[2,6-bis(Hyp)-Hgual] (15) überführt werden, dass wie 1 eine dimere Sandwich-Struktur aufweist. Durch Einführung des zweiten Hypersilylrestes werden die chemischen Eigenschaften des Azulenids dramatisch verändert. Während Verbindung 1 sich als guter Precursor für Metallocene erwies, gelang es uns bislang nicht, entsprechende Derivate der Verbindung 15 zu isolieren.

Quantum groups and vertex models

Nella tesi vengono presentate alcune relazioni fra gruppi quantici e modelli reticolari. In particolare si associa un modello vertex a una rappresentazione di un'algebra inviluppante quantizzata affine e si mostra che, specializzando il parametro quantistico ad una radice dell'unità, si manifestano speciali simmetrie.

Interpreting Judgements using Knowledge Representation Methods and Computational Models of Argument

The goal of the present research is to define a Semantic Web framework for precedent modelling, by using knowledge extracted from text, metadata, and rules, while maintaining a strong text-to-knowledge morphism between legal text and legal concepts, in order to fill the gap between legal document and its semantics. The framework is composed of four different models that make use of standard languages from the Semantic Web stack of technologies: a document metadata structure, modelling the main parts of a judgement, and creating a bridge between a text and its semantic annotations of legal concepts; a legal core ontology, modelling abstract legal concepts and institutions contained in a rule of law; a legal domain ontology, modelling the main legal concepts in a specific domain concerned by case-law; an argumentation system, modelling the structure of argumentation. The input to the framework includes metadata associated with judicial concepts, and an ontology library representing the structure of case-law. The research relies on the previous efforts of the community in the field of legal knowledge representation and rule interchange for applications in the legal domain, in order to apply the theory to a set of real legal documents, stressing the OWL axioms definitions as much as possible in order to enable them to provide a semantically powerful representation of the legal document and a solid ground for an argumentation system using a defeasible subset of predicate logics. It appears that some new features of OWL2 unlock useful reasoning features for legal knowledge, especially if combined with defeasible rules and argumentation schemes. The main task is thus to formalize legal concepts and argumentation patterns contained in a judgement, with the following requirement: to check, validate and reuse the discourse of a judge - and the argumentation he produces - as expressed by the judicial text.

Metabolomics reveals attenuation of the SLC6A20 kidney transporter in nonhuman primate and mouse models of type 2 diabetes mellitus

To enhance understanding of the metabolic indicators of type 2 diabetes mellitus (T2DM) disease pathogenesis and progression, the urinary metabolomes of well characterized rhesus macaques (normal or spontaneously and naturally diabetic) were examined. High-resolution ultra-performance liquid chromatography coupled with the accurate mass determination of time-of-flight mass spectrometry was used to analyze spot urine samples from normal (n = 10) and T2DM (n = 11) male monkeys. The machine-learning algorithm random forests classified urine samples as either from normal or T2DM monkeys. The metabolites important for developing the classifier were further examined for their biological significance. Random forests models had a misclassification error of less than 5%. Metabolites were identified based on accurate masses (<10 ppm) and confirmed by tandem mass spectrometry of authentic compounds. Urinary compounds significantly increased (p < 0.05) in the T2DM when compared with the normal group included glycine betaine (9-fold), citric acid (2.8-fold), kynurenic acid (1.8-fold), glucose (68-fold), and pipecolic acid (6.5-fold). When compared with the conventional definition of T2DM, the metabolites were also useful in defining the T2DM condition, and the urinary elevations in glycine betaine and pipecolic acid (as well as proline) indicated defective re-absorption in the kidney proximal tubules by SLC6A20, a Na(+)-dependent transporter. The mRNA levels of SLC6A20 were significantly reduced in the kidneys of monkeys with T2DM. These observations were validated in the db/db mouse model of T2DM. This study provides convincing evidence of the power of metabolomics for identifying functional changes at many levels in the omics pipeline.