Dans cette thèse, nous nous sommes attaqués au problème de séparation aveugle de mélanges linéaires de sources ayant des propriétés de cyclo-stationnarité. Trois applications ont été abordées à savoir : télécommunications, vibrations mécaniques et biomécaniques. Dans un premier temps, deux nouvelles méthodes ont été proposées, la première a pour but de séparer aveuglement des sources cyclo-stationnaires partageant une ou plusieurs fréquences cycliques inconnues. Elle combine la diagonalisation conjointe à un nouveau détecteur de points utiles (retard-fréquence cyclique) permettant de composer l’ensemble de matrices de corrélation cyclique devant être diagonalisées conjointement. Quant à la deuxième méthode, elle vise à identifier la matrice de mélange de sources cyclostationnaires de fréquences cycliques inconnues et différentes. L’identification commence par une étape de détection des matrices de rang un, puis décompose en éléments propres le produit de matrices sélectionnées, enfin une méthode de regroupement hiérarchique restitue les colonnes de notre matrice recherchée. Les deux solutions ont été appliquées aux signaux de télécommunications. Dans un second temps, nous avons appliqué d’abord la première méthode proposée sur des signaux mécaniques issus d’un banc de roulements défaillants afin de tester son aptitude à séparer les sources. Ensuite, nous avons proposé une approche qui s’appuie sur l’analyse en composantes parcimonieuses pour séparer les composantes de la force de réaction au sol ayant des propriétés cyclo-stationnaires à l’ordre 1 et 2 / In this thesis, we have tackled the problem of blind separation of linear mixtures of sources with cyclo-stationarity properties. Three applications were studied : telecommunications, mechanical vibrations and biomechanics. First, two new methods have been proposed, the first one aims to blindly separate cyclo-stationary sources sharing one or more unknown cyclic frequencies. It combines the joint diagonalization with a new useful point detector (time lag-cyclic frequency) to compose the set of cyclic correlation matrices to be jointly diagonalized. As for the second method, it aims to identify the mixture matrix of cyclo-stationary sources of unknown and different cyclic frequencies. The identification begins with a step of detecting the matrices of rank one, then the product of selected matrices is decomposed into eigen-elements, and finally a hierarchical regrouping method returns the columns of our sought matrix. Both solutions have been applied to telecommunications signals. In a second step, we first applied the first proposed method on mechanical signals coming from a bank of faulty bearings in order to test its ability to separate the sources. Next, we proposed an approach based on sparse component analysis to separate the components of the ground reaction force with cyclo-stationary properties at order 1 and 2

Avec l'augmentation de l'utilisation des smartphones, des objets connectés et des véhicules automatiques, le domaine des systèmes embarqués est devenu omniprésent dans notre environnement. Ces systèmes sont souvent contraints en terme de consommation et de taille. L'utilisation des processeurs many-cores dans des systèmes embarqués permet une conception rapide tout en respectant des contraintes temps-réels et en conservant une consommation énergétique basse.Exécuter une application sur un processeur many-core requiert un dispatching des tâches appelé problème de mapping et est connu comme étant NP-complet.Les contributions de cette thèse sont divisées en trois parties :Tout d'abord, nous étendons d'importantes propriétés dataflow au modèle Phased Computation Graph.Ensuite, nous présentons un générateur de graphe dataflow capable de générer des Synchonous Dataflow Graphs, Cyclo-Static Dataflow Graphs et Phased Computation Graphs vivant avec plus de 10000 tâches en moins de 30 secondes. Le générateur est comparé à SDF3 et PREESM.Enfin, la contribution majeure de cette thèse propose une nouvelle méthode d'évaluation d'un mapping en utilisant les modèles Synchonous Dataflow Graphe et Cyclo-Static Dataflow Graphe. La méthode évalue efficacement la mémoire consommée par les communications d'un dataflow mappé sur une architecture à mémoire distribuée. L'évaluation est déclinée en deux versions, la première garantit la vivacité alors que la seconde ajoute une contrainte de débit. La méthode d'évaluation est expérimentée avec des dataflow générés par Turbine et avec des applications réelles. / With the increasing use of smart-phones, connected objects or automated vehicles, embedded systems have become ubiquitous in our living environment. These systems are often highly constrained in terms of power consumption and size. They are more and more implemented with many-core processor array that allow, rapid design to meet stringent real-time constraints while operating at relatively low frequency, with reduced power consumption.Running an application on a processor array requires dispatching its tasks on the processors in order to meet capacity and performance constraints. This mapping problem is known to be NP-complete.The contributions of this thesis are threefold:First we extend important notions from the Cyclo-Static Dataflow Graph to the Phased Computation Graph model and two equivalent sufficient conditions of liveness.Second, we present a random dataflow graph generator able to generate Synchonous Dataflow Graphs, Cyclo-Static Dataflow Graphs and Phased Computation Graphs. The Generator, is able to generate live dataflow of up to 10,000 tasks in less than 30 seconds. It is compared with SDF3 and PREESM.Third and most important, we propose a new method of evaluation of a mapping using the Synchonous Dataflow Graph and the Cyclo-Static Dataflow Graph models. The method evaluates efficiently the memory footprint of the communications of a dataflow graph mapped on a distributed architecture. The evaluation is declined in two versions, the first guarantees a live mapping while the second accounts for a constraint on throughput.The evaluation method is experimented on dataflow graphs from Turbine and on real-life applications.

Le polyéthylène (PE) est omniprésent dans notre vie de tous les jours et ce principalement car il présente des propriétés thermiques et mécaniques qu'on ne retrouve pas d'autres polymères. Cependant, sa très faible réactivité chimique fait qu'il est difficile de l'incorporer dans des architectures macromoléculaires plus complexes qui pourraient profiter de ses propriétés uniques. La modification de polymères fonctionnels en extrémité de chaîne par des réactions de couplage efficaces est un outil très utilisé pour la conception d'architectures macromoléculaires. Parmi les différentes réactions envisageables, la réaction de cyclo-addition 1,3 dipolaire de Huisgen entre un azoture et un alcyne est très utilisée dans le domaine de la science des polymères pour lier des polymères entre eux. Une autre méthode performante est le couplage par une réaction d'addition de type hétéro Diels-Alder (HDA) entre un diène et un dithioformate. L'objectif de ce travail de thèse est dans un premier temps d'identifier un système de polymérisation catalytique de l'éthylène qui permette de synthétiser du polyéthylène de masse molaire variable et comportant à une extrémité une fonction réactive. Puis cette extrémité réactive est mise à profit dans des réactions de couplage efficaces comme celles mentionnées plus haut pour la synthèse d'architectures macromoléculaires incorporant des segments de PE

Parathormon (PTH) aktiviert am PTH-1 Rezeptor (P1R) mindestens zwei Signalwege: Über Guanosintriphosphat-bindende Proteine (Gs) kommt es intrazellulär zu einem Anstieg von zyklischem Adenosinmonophosphat (cAMP) und zu einer Aktivierung der Proteinkinase A (PKA). Gq Protein-vermittelt erfolgt eine Aktivierung der Phospholipase C (PLC) und ein intrazellulärer Anstieg des Inositoltriphosphat (IP3). Der verwandte PTH-2 Rezeptor (P2R) wird einerseits durch seinen vermutlich physiologischen Liganden, das tuberoinfundibuläre Peptid (TIP39), und andererseits durch PTH aktiviert. Im Gegensatz zum P1R zeigt der P2R nur eine Ankopplung an den cAMP Signalweg und keine an den PLC Signalweg. Voruntersuchungen hatten gezeigt, dass intrazelluläre Abschnitte der zweiten und dritten Schleife sowie Bereiche des C-Terminus des P1R für die Aktivierung des PLC Signalweges verantwortlich sind. In der vorliegenden Dissertation erfolgte eine stufenweise Angleichung intrazellulärer Abschnitte des P2R an den P1R. Die generierten Hybridrezeptoren wurden hinsichtlich ihres Signaltransduktionsverhaltens untersucht. Mit der Bestimmung der akkumulierten Gesamtinositole und des intrazellulären Calciums [Ca]i konnte gezeigt werden, dass trotz einer 95%-igen Übereinstimmung der intrazellulären Aminosäuresequenzen der P2R-Hybridrezeptoren mit denen des P1R, die Ankopplung an den PLC Signalweg nicht übertragen werden kann. Diese Ergebnisse wurden für Stimulationen mit PTH und TIP39 nachgewiesen. Durch Hemmung der Proteinkinasen A und C konnte, wie erwartet, am P1R ein verstärktes IP3 Signal beobachtet werden. Eine Aktivierbarkeit des PLC Signalweges wurde auch hierbei für die Hybridrezeptoren nicht gesehen. Für die Aktivierung des cAMP Signalweges der Hybridrezeptoren konnte beobachtet werden, dass diese sich weitestgehend in Anlehnung zum P2R verhalten. Außerdem konnte gezeigt werden, dass für eine effiziente Ankopplung an den cAMP Signalweg alle aus dem P1R in den P2R einfügten Teilabschnitte (zweite, dritte Schleife und C-Terminus) zusammenwirken. Der Hybridrezeptor, an dem alle drei Teilabschnitte ausgetauscht wurden, führte zu einer signifikant besseren Ankopplung an den cAMP Signalweg, als die Einzelmutation des C-Terminus. Die Messung zum cAMP Signalweg wurden mit den Liganden TIP39 und PTH durchgeführt. Für die Aktivierung des Gs Protein-vermittelten cAMP Signalweg am P1R oder P2R sind daher vermutlich Interaktionen verschiedener Rezeptorabschnitte verantwortlich. Insgesamt konnten in dieser Arbeit weitere wichtige Erkenntnisse bezüglich unterschiedlicher Aspekte der Signaltransduktion des P1R und des P2R gewonnen werden. / Activation of the phospholipase C (PLC) pathway upon stimulation with PTH is unique to the PTH-1 receptor (P1R) and is virtually absent in the PTH-2 receptor (P2R). The sites of P1R mutations known to reduce PLC signaling may achieve this indirectly by disturbing coupling at other sites. We therefore chose a more stringent approach and attempt to reestablish PLC signaling in the closely (70%) related P2R by gradually adapting the P2Rs cytosolic interface to a P1R-like sequence by engineering hybrid P1R/P2R constructs. Key differing regions of the P1R´s second loop (DT272-273:EK), third loop (IW344-345:LR), and C-terminal tail (T440-end: K-end) were put into the P2R. A fourth chimeric P1R/P2R receptor, combining all these changes, thus had a > 90% sequence identity with the cytosolic interface of the P1R. All mutants were expressed on the cell surface of stably transfected HEK 293 cells, using a radioreceptor assay with [125I]-Nle8,21-Tyr34-rat PTH(1-34), with a similar density of 1.1 to 2.5 mio receptors/cell. Activation of the PLC pathway was assessed by: 1) accumulation of total inositol phosphates in myo[3H]-inositol-prelabeled cells. No increase was detectable in the P2R or any of the receptor chimeras, even after enhancing the possible response by blockade of protein kinases A and C, despite an up to 13-fold increase with the P1R upon PTH stimulation. 2) Similarly, a PTH-induced increase in intracellular calcium (detected by fluo-3) of the wildtype P1R with as little as 1 nM hPTH(1-34) was completely absent in all mutants as well as in the P2R. The PTH-induced max. response of the cyclic AMP pathway was virtually identical for the P1R and P2R. However, the max. response of the mutant with the P1R tail sequence was reduced to only 35% (PTH) and 26% (TIP39) of the P2R response. Surprisingly, this signaling loss could be overcome by introducing more P1R sequence into the second and third cytoplasmic loop of this P1R/P2R hybrid receptor thus regaining a max. cAMP response of 64% (PTH) and 85% (TIP39). Presumably, an interaction of P1R sequences seems to result in a more effective coupling to the cAMP signaling pathway. In conclusion, these results suggest that the activation of the IP / intracellular calcium signaling pathway by the P1R is highly dependent on a P1R-like intracellular contact interface, which can not be mimicked easily even in the presence of > 90% of P1R sequence in the cytosolic interface of the P2R.

ACTH é o hormônio trófico que estimula a esteroidogênese, promove o crescimento e a manutenção do córtex adrenal. Porém, em linhagens adrenocorticais, assim como em culturas primárias, ACTH inibe a proliferação celular. A linhagem Y-1 de células adrenocorticais de camundongo tem as seguintes respostas a ACTH: aumento da esteroidogênese, arredondamento celular, bloqueio do ciclo celular em G1 e indução dos proto-oncogenes fos e jun. Esta linhagem também responde muito Sem a FGF2, um protótipo da família dos FGFs (Fibroblast Growth Factors) que regula diferenciação e proliferação de diversos tipos celulares, sendo estimulada a transitar pelas fases G0→G1→S do ciclo celular. ACTH antagoniza este efeito de FGF2, inibindo parcialmente a entrada em S induzida por FGF2. Este projeto buscou compreender o papel de c-Myc no controle do ciclo celular de Y-1, com ênfase nos efeitos de ACTH e FGF2 na expressão e atividade de c-Myc. Mostramos que os dois principais controles da expressão de c-Myc em Y-1 são transcrição e degradação da proteína, sendo a concentração de c-Myc o único controle sobre o sistema Myc/Max/Mad, uma vez que a expressão de Max e de Mad-1 , Mad-4 e Mxi é constitutiva em células Y-1. FGF2 induz a expressão de c-Myc através da indução da transcrição e aumento da estabilidade da proteína de forma totalmente dependente da via de Erk-MAPK. ACTH, por outro lado, não interfere com a transcrição de c-myc, mas promove fortemente a degradação da proteína, dependentemente da via de PKA. Utilizando um sistema de transfecção transiente, transfectamos uma quimera da proteína c-Myc com o receptor de estrógeno, MycER. Quando ativada por tamoxifen, a quimera migra para o núcleo e reverte a ação anti-mitogênica de ACTH sobre FGF2, porém, não tem efeito sobre células carenciadas tratadas ou não com ACTH apenas. Em conclusão, o antagonismo entre ACTH e FGF2 no controle da transição G0→G1→S do ciclo celular de Y-1 pode ser explicado pelas suas ações antagônicas sobre a estabilidade da proteína c-Myc. / ACTH is the trophic hormone that stimulates steroidogenesis, promotes growth and maintenance of the adrenal cortex. However, in adrenal cell lines, as well as in primary cultures, ACTH inhibits cell proliferation. ACTH effects on Y-1 cells are: increasing in steroidogenesis, cell rounding, cell cycle blocking in G1 phase and induction of fos and jun proto-oncogenes expression. Y-1 cell line displays a robust response to FGF2, a member from the FGFs family (Fibroblast Growth Factors), which regulates differentiation and proliferation in many cell types, being induced to enter G0→G1→S phases of fhe cell cycle upon FGF2 stimulation. ACTH antagonizes FGF2 effect, partially inhibiting cell cycle progression stimulated by FGF2. This project aimed to investigate c-Myc role in Y-1 cell cycle control, with emphasis on ACTH and FGF2 effects on its expression and activity control. We have shown that there are two main controls of c-Myc expression in Y-1 cells, transcription and protein stability. c-Myc concentration regulates the system Myc/Max/Mad, once Max and also Mad-1, Mad-4 and Mxi expression is constitutive in Y-1 cells. FGF2 induces c-Myc expression by increasing its transcription rate and stabilizing the protein in an Erk-MAPK pathway dependent manner. ACTH, on the other hand, does not control c-myc transcription but promotes a strong degradation of the protein through the PKA pathway. Using a transient transfection system, we were able to express MycER, a chimera of c-Myc and estrogen receptor in Y-1 cells. When activated by tamoxlfen, MycER is translocated to cell nucleus, where it abolishes the anti-mitogenic effect of ACTH over FGF2. However, it has no effect on cell cycle progression of serum starved cells treated or not with ACTH only. In conclusion, their antagonist effects on c-Myc protein stability can explain the antagonist effects of ACTH and FGF2 on the control of G0→G1→S transition of Y-1 cell cycle.

In this thesis, a compact and light primary switched conversion system for AC-fed railway propulsion is investigated. It is characterized by soft switching of all converter stages and a source commutated primary converter comprising series connected valves. Both weight and volume of the conversion system are reduced significantly compared to a conventional system with a low frequency transformer. The conversion system is made up of N isolated AC/DC conversion cells, each comprising a cycloconverter and a voltage source converter (VSC) coupled by a medium frequency transformer. The cells are series connected on the AC side and connected to a common DC-link. Thus, 2N+1 voltage levels can be synthesized at the AC terminal and the voltage stress on the transformer and line filter is reduced compared to a one cell solution. Series connection of semiconductor valves allows independent choice of blocking voltage and number of converter cells. Choosing two converter cells is an attractive compromise. Five level output reduces the harmonic distortion and simplify transformer and line filter design while keeping the complexity of the conversion system low. The mutually commutated converter (MCC) allows a transformer frequency in the range of 4 to 8 kHz without derating the line side converter due to zero voltage switching of the VSC. Modern magnetic materials, like high silicon steel, amorphous and noncrystalline materials allow design of the transformer with high efficiency at elevated frequencies. In a 15 kV system, the peak voltage at the catenary is typically beyond 32 kV which is far beyond the voltage capability of currently available semiconductors. Therefore, several semiconductors are connected in series. Favourable commutation conditions and a new gate drive arrangement allow snubberless commutation of the primary converter stage. Thus, the primary converter can be highly integrated, reducing both weight and volume. The conversion system can be placed on the roof or in the underframe without compromising efficiency or vehicle performance. The feasibility of the conversion concept has been demonstrated by means of a down-scaled prototype. Snubberless commutation of series connected valves is demonstrated. / QC 20100723

Favorisant plusieurs altérations physiologiques et autres conditions telle l'instabilité génomique, l'inflammation chronique joue un rôle central de l'initiation jusqu'au développement du cancer. Cette condition requiert la contribution de plusieurs types cellulaires et de médiateurs inflammatoires telle que la protéine transductrice du signal et activatrice de la transcription 3 (STAT3). Cette dernière est un médiateur majeur dans l'induction et le maintien d'un microenvironnement tumoral inflammatoire. En effet, la phosphorylation de STAT3 est essentielle à la régulation et à la transcription de plusieurs facteurs de croissance et cytokines incluant la cyclooxygénase-2 (COX)-2 et l'interleukine-6 (IL6), mais par son rôle de transducteur, elle répond aussi à plusieurs stimuli tant endogènes qu'environnementaux. Une des voies les plus importantes à cet effet est celle de JAK/STAT3. Une boucle rétroactive d'activation de STAT3 alimente d'ailleurs les processus impliqués dans le développement tumoral comme la prolifération, l'anti-apoptose, l'angiogenèse et la métastase. Les objectifs de notre étude sont, dans un premier temps, d'évaluer les effets de 5 polyphénols connus pour leur propriété anti-angiogénique; la lutéoline (Lut), l'apigénine (Api), l'épigallocatéchine gallate (EGCG), la delphinidine (Dp) et l'acide éllagique (EA), sur différentes étapes de l'angiogenèse déclenchée par l'IL-6 et d'en déterminer le mécanisme d'action au niveau moléculaire. Dans un deuxième temps, nous avons évalué chez les cellules souches mésenchymateuses (MSC) ayant un phénotype pro-inflammatoire induit par la concanavaline A (ConA), l'implication de la métalloprotéinase membranaire matricielle de type-1 (MT1-MMP) dans l'activation de STAT3 et l'expression de COX-2. Les résultats ont montré principalement que la Lut et l'Api inhibent très significativement la prolifération, la migration et la tubulogenèse des cellules endothéliales (EC) induite par l'IL-6 via la voie JAK/STAT3. En deuxième lieu, chez les MSC, la MT1-MMP semble être un contributeur important dans le phénotype pro-inflammatoire et implique également la voie JAK/STAT3. De façon inattendue l'inactivation de STAT3 potentialise l'expression de COX-2. Étant donné que les MSC sont recrutées aux sites inflammatoires de plusieurs cancers, ces résultats confirment l'importance de la MT1-MMP dans la régulation de la signalisation intracellulaire pro-inflammatoire des MSC. L'action double de STAT3 régulé par la MT1-MMP, montre son rôle majeur comme contributeur dans l'équilibre de l'expression de COX-2. Ce mécanisme permettrait ainsi aux MSC de s'adapter au microenvironnement inflammatoire pro-tumoral. Connaissant la diversité des polyphénols d'origine alimentaire et leur potentiel anti-inflammatoire, anti-angiogénique et anticancéreux on a aussi montré dans le cadre de cette étude que le potentiel de l'activité anti -inflammatoire de la Lut et d'Api permet, en partie d'expliquer leur activité anti-angiogénique et anti-cancer. Ainsi, ces flavones pourraient non seulement servir de base de recherche d'agents thérapeutiques anti-angiogéniques minimisant la résistance aux agents chimiothérapeutiques, mais aussi mettre en lumière le rôle majeur de l'alimentation dans la prévention du cancer. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : STAT3, MT1-MMP, angiogenèse, inflammation, IL6, COX-2

Many digital signal processing and real-time streaming systems are modeled using dataflow graphs, such as Synchronous Dataflow (SDF) and Cyclo-static Dataflow (CSDF) graphs that allow static analysis and optimization techniques. However, mapping of such descriptions into tightly constrained real-time implementations requires optimization of resource sharing, buffering and scheduling across a multi-dimensional latency-throughput-area objective space. This requires techniques that can find the Pareto-optimal set of implementations for the designer to choose from. In this work, we address the problem of multi-objective mapping and scheduling of SDF and CSDF graphs onto heterogeneous multi-processor platforms. Building on previous work, this thesis extends existing two-stage hybrid heuristics that combine an evolutionary algorithm with an integer linear programming (ILP) model to jointly optimize throughput, area and latency for SDF graphs. The primary contributions of this work include: (1) extension of the ILP model to support CSDFGs with additional buffer size optimizations; (2) a further optimization in the ILP-based scheduling model to achieve a runtime speedup of almost a factor of 10 compared to the existing SDFG formulation; (3) a list scheduling heuristic that replaces the ILP model in the hybrid heuristic to generate Pareto-optimal solutions at significantly decreased runtime while maintaining near-optimality of the solutions within an acceptable gap of 10% when compared to its ILP counterparts. The list scheduling heuristic presented in this work is based on existing modulo scheduling approaches for software pipelining in the compiler domain, but has been extended by introducing a new concept of mobility-based rescheduling before resorting to backtracking. It has been proved in this work that if mobility-based rescheduling is performed, the number of required backtrackings and hence overall complexity and runtime is less. / text

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / This study aimed to the chemical and pharmacological research of biodiversity of marine fungi associated with sediment from the coastline of northeastern Brazil, especially the state of CearÃ. From the collection of marine sediments at the beach Pecem - SÃo GonÃalo do Amarante-CE, were cultivated various fungi, of which the strain identified as Aspergillus sp. (BRF 087), showed a preliminary cytotoxic activity. The methodology has been directed in finding secondary metabolites with cytotoxic activity using a kinetic fungus study was grown in four different media, BD (potato dextrose), BDL (potato dextrose and yeast), MPD (malt, peptone and dextrose ) and MntPL (mannitol, peptone and yeast) and in different culture periods (7, 14, 21, 28 days). This procedure resulted in the isolation of nine diketopiperazines two tetrapeptides cycle, 3 derivatives of succinic acid and p-hydroxyphenylacetic acid, characterized as cyclo (L-Pro-L-Leu) (A-1), cyclo (L-Pro-L -Phe) (A-2), cyclo (4-OH-Pro-Leu) (A-3), cyclo (4-OH-Pro-Phe) (A-4), cyclo (L-Pro-L-tyr ) (A-5), cyclo (L-Leu-L-Val) (A-6), cyclo (L-Phe-L-Val) (A-7), cyclo (L-Phe-L-Leu) (A-8), cyclo (L-Leu-L-Ile) (A-9), cyclo (L-Ile-L-Pro-L-Leu-L-Pro) (A-10), cyclo (Leu-Ile Leu-Phe) (A-11), 2-metilenosuccinic acid (A-12), 3-Methyl-2-metilenosuccinic (A-13), 4-metoxy-2-methylidene-4-oxobutanoic acid (A-14) and p-hydroxyphenylacetic acid (A-15). The isolation of secondary metabolites was conducted by using usual chromatographic techniques, including chromatography on reverse phase C18 column and high-performance liquid chromatography (HPLC). For structural characterization of the compounds were used customary spectrometric techniques like IR, mass spectrometry and nuclear magnetic resonance (NMR), one and two dimensional, and compared with literature data. / O presente trabalho teve como objetivo principal a investigaÃÃo quÃmico-farmacolÃgica da biodiversidade dos fungos marinhos associados a sedimentos da costa litorÃnea do Nordeste do Brasil, e em especial do estado do CearÃ. A partir da coleta de sedimentos marinhos na praia do PecÃm - SÃo GonÃalo do Amarante-CE, foram cultivados vÃrios fungos, dos quais a cepa identificada como Aspergillus sp. (BRF 087), mostrou uma atividade citotÃxica preliminar. A metodologia empregada foi direcionada na busca de metabÃlitos secundÃrios com atividade citotÃxica, atravÃs de um estudo cinÃtico do fungo que foi cultivado em quatro meios diferentes, BD (batata dextrose), BDL (batata dextrose e levedura), MPD (malte, peptona e dextrose) e MntPL (manitol, peptona e levedura) e em diferentes perÃodos de cultivo (7, 14, 21, 28 dias). Este procedimento resultou no isolamento de nove dicetopiperazinas, dois ciclo tetrapeptÃdeos, 3 derivados do Ãcido succinio e o Ãcido p-hidroxifenilacÃtico, caracterizados como ciclo (L-Pro-L-Leu) (A-1), ciclo (L-Pro-L-Fen) (A-2),ciclo (4-OH-Pro-Leu) (A-3), ciclo (4-OH-Pro-Fen) (A-4), ciclo (L-Pro-L-Tyr) (A-5), ciclo (L-Leu-L-Val) (A-6), ciclo (L-Fen-L-Val) (A-7), ciclo (L-Fen-L-Leu) (A-8), ciclo (L-Leu-L-Ile) (A-9), ciclo (L-Ile-L-Pro-L-Leu-L-Pro) (A-10), ciclo (Leu-Ile-Leu-Fen) (A-11), Ãcido 2-metilenosuccinio (A-12), Ãcido 3-metil-2-metilenosuccinio (A-13), Ãcido 4-metoxi-2-metileno-4-oxobutanÃico (A-14) e o Ãcido p-hidroxifenilacÃtico (A-15). O isolamento dos metabÃlitos secundÃrios foi realizado atravÃs do uso de tÃcnicas cromatogrÃficas usuais, incluindo cromatografia em coluna de fase reversa C18 e cromatografia lÃquida de alta eficiÃncia (CLAE). Para a caracterizaÃÃo estrutural dos compostos foram utilizadas tÃcnicas espectromÃtricas usuais como infravermelho, espectrometria de massa e ressonÃncia magnÃtica nuclear (RMN), uni e bidimensional, alÃm de comparaÃÃo com dados da literatura.

ACTH é o hormônio trófico que estimula a esteroidogênese, promove o crescimento e a manutenção do córtex adrenal. Porém, em linhagens adrenocorticais, assim como em culturas primárias, ACTH inibe a proliferação celular. A linhagem Y-1 de células adrenocorticais de camundongo tem as seguintes respostas a ACTH: aumento da esteroidogênese, arredondamento celular, bloqueio do ciclo celular em G1 e indução dos proto-oncogenes fos e jun. Esta linhagem também responde muito Sem a FGF2, um protótipo da família dos FGFs (Fibroblast Growth Factors) que regula diferenciação e proliferação de diversos tipos celulares, sendo estimulada a transitar pelas fases G0→G1→S do ciclo celular. ACTH antagoniza este efeito de FGF2, inibindo parcialmente a entrada em S induzida por FGF2. Este projeto buscou compreender o papel de c-Myc no controle do ciclo celular de Y-1, com ênfase nos efeitos de ACTH e FGF2 na expressão e atividade de c-Myc. Mostramos que os dois principais controles da expressão de c-Myc em Y-1 são transcrição e degradação da proteína, sendo a concentração de c-Myc o único controle sobre o sistema Myc/Max/Mad, uma vez que a expressão de Max e de Mad-1 , Mad-4 e Mxi é constitutiva em células Y-1. FGF2 induz a expressão de c-Myc através da indução da transcrição e aumento da estabilidade da proteína de forma totalmente dependente da via de Erk-MAPK. ACTH, por outro lado, não interfere com a transcrição de c-myc, mas promove fortemente a degradação da proteína, dependentemente da via de PKA. Utilizando um sistema de transfecção transiente, transfectamos uma quimera da proteína c-Myc com o receptor de estrógeno, MycER. Quando ativada por tamoxifen, a quimera migra para o núcleo e reverte a ação anti-mitogênica de ACTH sobre FGF2, porém, não tem efeito sobre células carenciadas tratadas ou não com ACTH apenas. Em conclusão, o antagonismo entre ACTH e FGF2 no controle da transição G0→G1→S do ciclo celular de Y-1 pode ser explicado pelas suas ações antagônicas sobre a estabilidade da proteína c-Myc. / ACTH is the trophic hormone that stimulates steroidogenesis, promotes growth and maintenance of the adrenal cortex. However, in adrenal cell lines, as well as in primary cultures, ACTH inhibits cell proliferation. ACTH effects on Y-1 cells are: increasing in steroidogenesis, cell rounding, cell cycle blocking in G1 phase and induction of fos and jun proto-oncogenes expression. Y-1 cell line displays a robust response to FGF2, a member from the FGFs family (Fibroblast Growth Factors), which regulates differentiation and proliferation in many cell types, being induced to enter G0→G1→S phases of fhe cell cycle upon FGF2 stimulation. ACTH antagonizes FGF2 effect, partially inhibiting cell cycle progression stimulated by FGF2. This project aimed to investigate c-Myc role in Y-1 cell cycle control, with emphasis on ACTH and FGF2 effects on its expression and activity control. We have shown that there are two main controls of c-Myc expression in Y-1 cells, transcription and protein stability. c-Myc concentration regulates the system Myc/Max/Mad, once Max and also Mad-1, Mad-4 and Mxi expression is constitutive in Y-1 cells. FGF2 induces c-Myc expression by increasing its transcription rate and stabilizing the protein in an Erk-MAPK pathway dependent manner. ACTH, on the other hand, does not control c-myc transcription but promotes a strong degradation of the protein through the PKA pathway. Using a transient transfection system, we were able to express MycER, a chimera of c-Myc and estrogen receptor in Y-1 cells. When activated by tamoxlfen, MycER is translocated to cell nucleus, where it abolishes the anti-mitogenic effect of ACTH over FGF2. However, it has no effect on cell cycle progression of serum starved cells treated or not with ACTH only. In conclusion, their antagonist effects on c-Myc protein stability can explain the antagonist effects of ACTH and FGF2 on the control of G0→G1→S transition of Y-1 cell cycle.