Mitochondria and metabolism: the role of SAGA complex in budding yeast respiration

Mitochondrion is the energy center of the cell in which different metabolic pathways converge. Cell respiration takes place in this organelle with high production of ATP. Nucleus-mitochondrion communication represents an essential level of cell homeostasis regulation. This crosstalk is strictly related to epigenetic mechanisms, in particular to histone and non-histone proteins acetylation. Budding yeast is a suitable model system to study the interplay between epigenetic and metabolism; in this organism it is possible to analyse fermentative and respiratory pathways varying the carbon source in growth medium. SAGA complex is a transcriptional co-activator with two catalytic domains: the deubiquitination module with DUB Ubp8 and the acetylation domain with HAT Gcn5. In yeast, Gcn5 has a major role in protein acetylation at global and specific lysine; moreover, it is implicated in mitochondrion-nucleus communication. In this work, we found that SAGA complex and its catalytic activities are necessary for cell respiration. Results showed that KAT Gcn5 and DUB Ubp8 are upregulated in respiration at both transcriptional and protein levels. We identify two interactors, the E3 ubiquitin ligase Psh1 and the HDAC Hda1, whose deletion is able to rescue defective respiratory phenotype of strains lacking respectively Ubp8 and Gcn5. We demonstrated that histone residue H3K18 is the preferential target of Hda1 and Gcn5 and its acetylation is needed in respiration. Surprising, we found that Gcn5, Ubp8 and Psh1 localize in both nucleus and mitochondria highlighting a dual role as chromatin modifiers and mitochondrial factors. Moreover, our data showed that Ubp8 expression is regulated by Gcn5, while its cell localization is influenced by Psh1. Finally, results suggest that acetylation is an important mark in respiratory condition

Gcn5 histone acetyltransferase is present in the mitoplasts

In Saccharomyces cerevisiae the Lysine-acetyltransferase Gcn5 (KAT2) is part of the SAGA complex and is responsible for histone acetylation widely or at specific lysines. In this paper we report that GCN5 deletion differently affects the growth of two strains. The defective mitochondrial phenotype is related to a marked decrease in mtDNA content, which also involves the deletion of specific regions of the molecule. We also show that in wild-type mitochondria the Gcn5 protein is present in the mitoplasts, suggesting a new mitochondrial function independent from the SAGA complex and possibly a new function for this protein connecting epigenetics and metabolism

Drosophila melanogaster, un modelo animal emergente en el estudio de enfermedades cardíacas humanas

Background: The need to work with model organisms in medical research has revealed the usefulness of the fruit fly Drosophila melanogaster, considering its advantages to perform classic genetic studies and modern techniques of genome edition. Several human genes are similar to those of the fruit fly. We have developed for the first time in the country a cardiovascular line of research to study the genetics of aging, addictions and chronic consumption of substances in humans like caffeine. Objective: The aim of this study was to provide experimental evidence that validates Drosophila melanogaster as a model to study human cardiomyopathies related to the pharmacological action of caffeine on the heart. Methods: Cardiac function and the effect of caffeine were studied in semi-intact preparations of Drosophila melanogaster. Heart rate and the intracellular calcium transient were recorded and analyzed in 3, 7 and 40-day-old adult flies harboring one genetically encoded reporter system. Hearts of adult flies were dissected to show the myofibrillar structural organization and specific proteins such as SERCA. Results: Aging and caffeine alter contraction rate and intracellular calcium handling in the adult heart of Drosophila melanogaster in a similar way as mammals Conclusion: The study supports the use of this model of fast and easy reproductive cycle to identify the genes involved in the mechanisms through which aging, caffeine (and other substances) and environmental factors affect the heart.Introducción: La necesidad de trabajar con modelos de organismos en la investigación sobre salud ha revelado las utilidades de la mosca de la fruta Drosophila melanogaster considerando sus ventajas para realizar genética clásica y modernas técnicas de edición del genoma. Muchos genes humanos son homólogos a los genes de la mosca. Hemos desarrollado por primera vez en el país una línea de investigación cardiovascular para estudiar la genética del envejecimiento, las adicciones y sustancias de consumo crónico en el humano como la cafeína. Objetivo: Aportar evidencia experimental que valida el modelo de Drosophila melanogaster para el estudio de miocardiopatías humanas en relación con la acción farmacológica de la cafeína sobre el corazón. Material y métodos: Se analizaron la función cardíaca y el efecto de la cafeína en preparados semiintactos de Drosophila melanogaster. Se registró la frecuencia cardíaca y se analizó el transitorio de calcio intracelular en moscas adultas de 3, 7 y 40 días mediante un reportero codificado genéticamente. Corazones de moscas adultas se disecaron para mostrar la organización estructural de las miofibrillas y proteínas específicas como la SERCA. Resultados: La cafeína y el envejecimiento afectan la frecuencia de contracción y el manejo de calcio intracelular en el corazón adulto de Drosophila melanogaster en forma similar a lo que ocurre en mamíferos. Conclusión: El estudio abre la posibilidad de usar este modelo de fácil y rápida reproducción en busca de genes que permitan conocer los mecanismos por los cuales el envejecimiento, la cafeína (u otros compuestos) y factores ambientales actúan sobre el corazón.Facultad de Ciencias Médicas (FCM)Facultad de Ciencias Veterinarias (FCV

Développement de capteurs électrochimiques basés sur des ensembles de nanoélectrodes

Dans le cadre de cette thèse nous avons élaboré et optimisé une procédure de fabrication de réseaux de nanofils métalliques incorporé dans une matrice de polymère. Les propriétés physico-chimiques des réseaux ont été étudié. La surface constituant un ensemble de nanoélectrodes a été modifiée par des monocouches autoassemblées de molécules possédant des propriétés catalytiques. Ceci a permis ensuite l'adsorption de substances bioactives, comme des enzymes, qui montrent des propriétés de reconnaissance moléculaire. Lénsemble de nanoélectrodes modifié ainsi a été testé avec succès comme biocapteur électrochimique..

Knockdown of DOM/Tip60 complex subunits impairs male meiosis of Drosophila melanogaster

ATP-dependent chromatin remodeling complexes are involved in nucleosome sliding and eviction and/or the incorporation of histone variants into chromatin to facilitate several cellular and biological processes, including DNA transcription, replication and repair. The DOM/TIP60 chromatin remodeling complex of Drosophila melanogaster contains 18 subunits, including the DOMINO (DOM), an ATPase that catalyzes the exchange of the canonical H2A with its variant (H2A.V), and TIP60, a lysine-acetyltransferase that acetylates H4, H2A and H2A.V histones. In recent decades, experimental evidence has shown that ATP-dependent chromatin remodeling factors, in addition to their role in chromatin organization, have a functional relevance in cell division. In particular, emerging studies suggested the direct roles of ATP-dependent chromatin remodeling complex subunits in controlling mitosis and cytokinesis in both humans and D. melanogaster. However, little is known about their possible involvement during meiosis. The results of this work show that the knockdown of 12 of DOM/TIP60 complex subunits generates cell division defects that, in turn, cause total/partial sterility in Drosophila males, providing new insights into the functions of chromatin remodelers in cell division control during gametogenesis

Preliminary Studies on the Iodide Determination in the Marine Environment by Nanoelectrode Ensembles.

Ensembles of gold nanodisk electrodes( NEE,- Nano ElectrodesEnsemble)30 nm in diameter are presented, focusing on their capability of furnishing improved signal/background current ratios with respect to conventional electrodes. NEEs are employed here for the voltammetric determination of iodide concentration in samples of interest in marine environmental studies. Specifically, NEEs are applied to determine directly the iodide at micromolar concentration levels in iodized edible salt by cyclic voltammetry as well as at sub-micromolar concentration levels in lagoon waters by square wave voltammetry

Drosophila melanogaster, un modelo animal emergente en el estudio de enfermedades cardíacas humanas

Background: The need to work with model organisms in medical research has revealed the usefulness of the fruit fly Drosophila melanogaster, considering its advantages to perform classic genetic studies and modern techniques of genome edition. Several human genes are similar to those of the fruit fly. We have developed for the first time in the country a cardiovascular line of research to study the genetics of aging, addictions and chronic consumption of substances in humans like caffeine. Objective: The aim of this study was to provide experimental evidence that validates Drosophila melanogaster as a model to study human cardiomyopathies related to the pharmacological action of caffeine on the heart. Methods: Cardiac function and the effect of caffeine were studied in semi-intact preparations of Drosophila melanogaster. Heart rate and the intracellular calcium transient were recorded and analyzed in 3, 7 and 40-day-old adult flies harboring one genetically encoded reporter system. Hearts of adult flies were dissected to show the myofibrillar structural organization and specific proteins such as SERCA. Results: Aging and caffeine alter contraction rate and intracellular calcium handling in the adult heart of Drosophila melanogaster in a similar way as mammals Conclusion: The study supports the use of this model of fast and easy reproductive cycle to identify the genes involved in the mechanisms through which aging, caffeine (and other substances) and environmental factors affect the heart.Introducción: La necesidad de trabajar con modelos de organismos en la investigación sobre salud ha revelado las utilidades de la mosca de la fruta Drosophila melanogaster considerando sus ventajas para realizar genética clásica y modernas técnicas de edición del genoma. Muchos genes humanos son homólogos a los genes de la mosca. Hemos desarrollado por primera vez en el país una línea de investigación cardiovascular para estudiar la genética del envejecimiento, las adicciones y sustancias de consumo crónico en el humano como la cafeína. Objetivo: Aportar evidencia experimental que valida el modelo de Drosophila melanogaster para el estudio de miocardiopatías humanas en relación con la acción farmacológica de la cafeína sobre el corazón. Material y métodos: Se analizaron la función cardíaca y el efecto de la cafeína en preparados semiintactos de Drosophila melanogaster. Se registró la frecuencia cardíaca y se analizó el transitorio de calcio intracelular en moscas adultas de 3, 7 y 40 días mediante un reportero codificado genéticamente. Corazones de moscas adultas se disecaron para mostrar la organización estructural de las miofibrillas y proteínas específicas como la SERCA. Resultados: La cafeína y el envejecimiento afectan la frecuencia de contracción y el manejo de calcio intracelular en el corazón adulto de Drosophila melanogaster en forma similar a lo que ocurre en mamíferos. Conclusión: El estudio abre la posibilidad de usar este modelo de fácil y rápida reproducción en busca de genes que permitan conocer los mecanismos por los cuales el envejecimiento, la cafeína (u otros compuestos) y factores ambientales actúan sobre el corazón.Facultad de Ciencias Médicas (FCM)Facultad de Ciencias Veterinarias (FCV

Big-data-driven modeling unveils country-wide drivers of endemic schistosomiasis

Schistosomiasis is a parasitic infection that is widespread in sub-Saharan Africa, where it represents a major health problem. We study the drivers of its geographical distribution in Senegal via a spatially explicit network model accounting for epidemiological dynamics driven by local socioeconomic and environmental conditions, and human mobility. The model is parameterized by tapping several available geodatabases and a large dataset of mobile phone traces. It reliably reproduces the observed spatial patterns of regional schistosomiasis prevalence throughout the country, provided that spatial heterogeneity and human mobility are suitably accounted for. Specifically, a fine-grained description of the socioeconomic and environmental heterogeneities involved in local disease transmission is crucial to capturing the spatial variability of disease prevalence, while the inclusion of human mobility significantly improves the explanatory power of the model. Concerning human movement, we find that moderate mobility may reduce disease prevalence, whereas either high or low mobility may result in increased prevalence of infection. The effects of control strategies based on exposure and contamination reduction via improved access to safe water or educational campaigns are also analyzed. To our knowledge, this represents the first application of an integrative schistosomiasis transmission model at a whole-country scale

The spatial spread of schistosomiasis: A multidimensional network model applied to Saint-Louis region, Senegal

AbstractSchistosomiasis is a parasitic, water-related disease that is prevalent in tropical and subtropical areas of the world, causing severe and chronic consequences especially among children. Here we study the spatial spread of this disease within a network of connected villages in the endemic region of the Lower Basin of the Senegal River, in Senegal. The analysis is performed by means of a spatially explicit metapopulation model that couples local-scale eco-epidemiological dynamics with spatial mechanisms related to human mobility (estimated from anonymized mobile phone records), snail dispersal and hydrological transport of schistosome larvae along the main water bodies of the region. Results show that the model produces epidemiological patterns consistent with field observations, and point out the key role of spatial connectivity on the spread of the disease. These findings underline the importance of considering different transport pathways in order to elaborate disease control strategies that can be effective within a network of connected populations