Análisis de la especificación de las neuronas Va en la Cuerda Nerviosa Ventral de Drosophila melanogaster

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Biología Molecular. Fecha de lectura: 18-06-2014Durante el desarrollo embrionario, cada una de las células originadas a partir de los progenitores neurales, conocidos como neuroblastos (NB), adquiere un destino celular concreto que responde a diferentes requerimientos funcionales y estructurales, como los establecidos a lo largo del eje Antero-Posterior (A-P) del individuo. La familia de genes Hox interviene de manera decisiva en el desarrollo de las estructuras morfológicamente diferentes encontradas a lo largo del eje A-P, incluyendo la diferenciación de los linajes de NBs. Para profundizar en el conocimiento de los mecanismos involucrados en este proceso, se ha estudiado el desarrollo del sistema de neuronas Va, una serie de neuronas homologas creadas por NBs homólogos en segmentos diferentes. Dichas neuronas se originan en estadios tempranos en todos los segmentos de la Cuerda Nervioso Ventral (CNV) como neuronas equivalentes, pero posteriormente sufren 4 procesos de especificación distintos determinados por la acción, aparentemente post-mitótica, de los genes Hox. La actuación de Abd-B provoca la apoptosis de las neuronas de los segmentos A5-A7. En los segmentos torácicos, las neuronas dejan de ser localizables a partir de estadio 15 tardío, y Antp determina su destino desconocido. Las neuronas Va de los segmentos A2-A4 expresan el neuropéptido Capability (Capa) (Va-Capa) bajo la influencia del gen abd-A, mientras que Ubx determina la expresión de Alatostatina-A (Ast-A) y la Hormona Diurética 31 (DH31) en el segmento A1 (Va-DH31). Se trata por tanto del primer caso en el que la acción de los genes Hox determina 4 destinos celulares diferentes a partir de una serie de neuronas homólogas, 2 de los cuales resultan ser destinos peptidérgicos. Para finalizar, se ha llevado a cabo un screening genético en el que se han identificado varios genes implicados en la correcta especificación de las neuronas Va-Capa. Entre ellos se encuentran scribbler (sbb) y dachshund (dac), que resultan imprescindibles para la muerte celular dirigida por Abd-B de las neuronas Va de los segmentos A5-A6. Además, se describe cómo el factor de transcripción Klumpfuss resulta esencial en el proceso de división asimétrica de la Célula Madre Ganglionar (CMG), diferenciando el destino de las neuronas Va que expresan Capa (Va-Capa) y del de sus neuronas hermanas que sufren apoptosis. En mutantes klu, se producen dos neuronas de tipo Notch-OFF, que expresan Capa, en vez de una de tipo Notch-OFF y otra Notch-ON. Además de incrementar el conocimiento sobre los procesos de especificación neural, a través de esta tesis se ha perfilado el sistema de las neuronas Va como un valioso modelo con el que llevar a cabo futuras investigaciones sobre importantes aspectos del desarrollo de la CNV de Drosophila.During embryogenesis, cells of the Central Nervous System (SNC) are generated from neural progenitors, called neuroblasts (NB). Different functional and structural requirements, as those found along the anteroposterior axis (A-P) of the individual, are endowed by specific cellular fates acquired by each neuron. The Hox gene family plays a key role in the development of morphologically distinct structures along the A-P axis, including the differentiation of diverse NBs lineages. To gain insights into the underlying mechanisms involved in this process, this thesis focuses on the Va neuronal system, which includes a series of homologous neurons which originate from homologous NBs at different segments of the Ventral Nerve Cord (CNV). Initially, during the early stages of the development, these neurons appear in all segments as equivalent cells, but subsequently undergo 4 different specification processes, determined by the action of the Hox genes through apparently post-mitotic mechanisms. In this scenario, the Abdominal-B gene (Abd-B) induces apoptosis in the A5 -A7 segments. The Va neurons in the thoracic segments cannot be traced from late stage 15 onwards, and Antp gene determines its unknown fate. The Va neurons in the A2 -A4 segments express the neuropeptide Capability (Capa; Va-Capa neurons) under the abd-A gene influence, whereas Allatostatine -A (Ast -A) and Diuretic Hormone 31 (DH31; Va-DH31 neurons) are expressed in the A1 segment due to the action of Ubx. Thus, this system represents the first case in which the action of Hox genes determines 4 different cell fates from a series of homologous neurons, 2 of which are peptidergic. Furthemore, a targeted genetic screening was conducted to identify genes involved in the specification of Va- Capa neurons. Among the candidate genes, scribbler (sbb) and dachshund (dac) were shown to be essential for the programmed cell death triggered by Abd-B in the A5- A6 segments. In addition, the transcription factor Klumpfuss was identified as an essential element in the asymmetric division of the Ganglion Mother Cell (GMC), acting to differentiate between the Va-Capa neurons and their siblings, which undergo apoptosis. This role of Klumpsfuss explains why klu mutants exhibit two Notch-OFF type neurons, which express Capa, instead of one Notch-OFF and its respective Notch-ON sibling cell. Beyond increasing the knowledge about the process of neural specification, this thesis has portrayed the Va neuronal system as a valuable model to explore important aspects of the development of the CNV in Drosophila

Bioactive compounds of two orange-fleshed sweet potato cultivars (Ipomoea batatas (L.) Lam.) in fresh, stored and processed roots

Sweet potatoes are a rich source of bioactive compounds, which are considered to promote human health. This study aimed to analyse the main bioactives of two orange-fleshed sweet potato cultivars, Beauregard and Colorado INTA, freshly harvested, after storage, and after processing of sweet potato paste, a solid dessert widely consumed in Argentina. In the flesh, phenolic compounds, carotenoids, anthocyanin contents, and radical scavenging activity were significantly higher in Colorado INTA cultivar. The carotenoid contents were 555 and 712 µg β-carotene/g dw in the flesh of Beauregard and Colorado INTA, respectively. In the peel of both cultivars, phenolic contents and antioxidant activities were notably higher than in the flesh. Extended storage has markedly increased phenolics and antioxidant properties in the flesh of Colorado INTA, further accentuating the differences between both cultivars. Paste processing negatively affected all parameters, particularly in Beauregard. The major phenolic compounds in both cultivars, chlorogenic and 3,5-dicaffeoylquinic acids, were the most affected by processing. The main reductions of bioactives stemmed from sugar addition. The inclusion of the peel, traditionally discarded during processing, could confer an additional value to the paste. The high bioactive contents of Beauregard and Colorado INTA cultivars, especially the latter, can contribute to provide health benefits and to reduce vitamin A deficiency. The valuable attributes of these cultivars could represent a useful tool for sweet potato producers to add value to this product and to foment its consumption.EEA San PedroFil: Gabilondo, Julieta. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria San Pedro; ArgentinaFil: Corbino, Graciela Beatriz. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria San Pedro; ArgentinaFil: Corbino, Graciela Beatriz. Universidad de Buenos Aires. Facultad de Agronomía. Cátedra de Química de Biomoléculas; ArgentinaFil: Chludil, Hugo Daniel. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Biología Aplicada y Alimentos; ArgentinaFil: Chludil, Hugo Daniel. Universidad de Buenos Aires. Facultad de Agronomía. Parque Científico y Tecnológico; ArgentinaFil: Malec, Laura. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento Química Orgánica; Argentin

Description and selection within a peach backcross population and parental segregation for the aptitude for fruits postharvest conservation trait

PosterThe aim of this study was to describe the quality characteristics of fruits from 45 peach genotypes obtained from the backcross (BC1) between Dixiland and DixFla 141 (a hybrid between Dixiland x Flavorcrest), make a preliminary selection and assessment the aptitude for conservation of Dixiland, Flavorcrest and DixFla 141.EEA San PedroFil: Chirino, Julián Santiago. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria San Pedro; ArgentinaFil: Gabilondo, Julieta. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria San Pedro; ArgentinaFil: Budde, Claudio Olaf. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria San Pedro; ArgentinaFil: Valentini, Gabriel Hugo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria San Pedro; ArgentinaFil: Sánchez, Gerardo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria San Pedro; Argentin

Segmentally homologous neurons acquire two different terminal neuropeptidergic fates in the Drosophila nervous system

This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. In this study, we identify the means by which segmentally homologous neurons acquire different neuropeptide fates in Drosophila. Ventral abdominal (Va)-neurons in the A1 segment of the ventral nerve cord express DH31 and AstA neuropeptides (neuropeptidergic fate I) by virtue of Ubx activity, whereas the A2-A4 Va-neurons express the Capa neuropeptide (neuropeptidergic fate II) under the influence of abdA. These different fates are attained through segment-specific programs of neural subtype specification undergone by segmentally homologous neurons. This is an attractive alternative by which Hox genes can shape Drosophila segmental neural architecture (more sophisticated than the previously identified binary “to live” or “not to live” mechanism). These data refine our knowledge of the mechanisms involved in diversifying neuronal identity within the central nervous systemThis study was supported by grant number: BFU2013-43858-

Seven up acts as a temporal factor during two different stages of neuroblast 5-6 development

Drosophila embryonic neuroblasts generate different cell types at different time points. This is controlled by a temporal cascade of HbrKrrPdmrCasrGrh, which acts to dictate distinct competence windows sequentially. In addition, Seven up (Svp), a member of the nuclear hormone receptor family, acts early in the temporal cascade, to ensure the transition from Hb to Kr, and has been referred to as a ‘switching factor’. However, Svp is also expressed in a second wave within the developing CNS, but here, the possible role of Svp has not been previously addressed. In a genetic screen for mutants affecting the last-born cell in the embryonic NB5-6T lineage, the Ap4/FMRFamide neuron, we have isolated a novel allele of svp. Expression analysis shows that Svp is expressed in two distinct pulses in NB5-6T, and mutant analysis reveals that svp plays two distinct roles. In the first pulse, svp acts to ensure proper downregulation of Hb. In the second pulse, which occurs in a Cas/Grh double-positive window, svp acts to ensure proper sub-division of this window. These studies show that a temporal factor may play dual roles, acting at two different stages during the development of one neural lineage.This work was supported by the Swedish Research Council, by the Swedish Strategic Research Foundation, by the Knut and Alice Wallenberg foundation, by the Swedish Brain Foundation, by the Swedish Cancer Foundation, by the Swedish Royal Academy of Sciences [S.T.], and by a grant from the Spanish Ministerio de Ciencia e Innovación [BFU-2008-04683-C02-02 to L.T.]

Reform of the Coal Sector in an Open Economy: The Case of China

Cheap, abundant and easy to transport and store, coal has been produced and consumed to meet people's energy needs. The last decade's growth in global coal use has been driven mainly by developing economies like China, whose phenomenal economic growth has been powered by coal-fired electricity and promoted by the export of manufactured goods. A recent reform focus in China's coal sector is on coal taxation. The paper develops a game-theoretic model tailored to the context of China where coal taxation reform takes place against the background of privatisation of coal firms and an open economy. It finds that the adoption of special coal taxes is optimal for social welfare under most circumstances, but may induce coal firms to commit opportunistic behaviour in the process of privatisation. The paper also cautions about potential resistance to the reform from consumers, coal firms and government officials

Variación de ácidos fenólicos en dos cultivares de batata durante el almacenamiento

El objetivo de este trabajo fue estudiar y comparar el contenido de polifenoles totales (PFT), la actividad antioxidante (AA) y separar los principales fenoles ácidos en piel y pulpa de dos cultivares de batata (Beauregard y Colorado INTA) en el producto fresco y luego de 90 días de almacenamiento en cámara a 13°C. El contenido de PFT se determinó con el reactivo de Folin-Ciocalteau, la AA mediante la reducción del radical 2,2-difenil-1-picril-hidracilo (DPPH·) y los fenoles ácidos mediante cromatografía líquida de alta resolución (HPLC) en fase reversa. El contenido de PFT y la AA tanto en la pulpa como en la piel, resultaron considerablemente mayores en el cultivar Colorado INTA. Los valores de PFT y AA obtenidos en la piel, fueron superiores a los de la pulpa para ambos cultivares. Después del almacenamiento, el contenido de PFT y la AA aumentaron en la pulpa del cultivar Colorado INTA. Por el contrario, en la piel, ambos parámetros disminuyeron aproximadamente 30% en ambos cultivares. Los principales fenoles identificados fueron los isómeros de los ácidos clorogénico y dicafeoilquínicos. El incremento observado en los compuestos bioactivos de la batata acentuaron aún más las diferencias entre las propiedades funcionales de ambos cultivares. Abstract: The aim of this work was to study and to compare the content of total polyphenols (PP), the antioxidant activity (AA) and to separate the main phenolic acids in skin and pulp of two sweetpotato cultivars (Beauregard and Colorado INTA) in the fresh product and after 90 days of storage at 13°C chamber .The PP content was determined with the Folin-Ciocalteu reagent, AA by 2,2-diphenyl-1-picrylhydrazyl radical (DPPH·) radical-scavenging activity assay and phenolic acids were performed by high performance liquid chromatography (HPLC) on reversed phase. The PP content and AA in pulp and skin were significantly higher in the cultivar Colorado INTA. PP and AA values obtained from skin were superior to those of pulp for both cultivars. After storage, the PP and AA increased in the pulp of cultivar Colorado INTA. By contrast, both parameters decreased approximately 30 % in the skin of both cultivars. The main polyphenols identified were the isomers of chlorogenic and dicaffeoylquinic acids. The observed increase of the bioactive compounds of the sweetpotatoes during storage further accentuated the differences between the functional properties of both cultivars.EEA San PedroFil: Gabilondo, Juieta. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria San Pedro; ArgentinaFil: Corbino, Graciela. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria San Pedro; ArgentinaFil: Chludil, Hugo. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Malec, Laura. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentin

A targeted genetic screen identifies crucial players in the specification of the Drosophila abdominal Capaergic neurons

The central nervous system contains a wide variety of neuronal subclasses generated by neural progenitors. The achievement of a unique neural fate is the consequence of a sequence of early and increasingly restricted regulatory events, which culminates in the expression of a specific genetic combinatorial code that confers individual characteristics to the differentiated cell. How the earlier regulatory events influence post-mitotic cell fate decisions is beginning to be understood in the Drosophila NB 5-6 lineage. However, it remains unknown to what extent these events operate in other lineages. To better understand this issue, we have used a very highly specific marker that identifies a small subset of abdominal cells expressing the Drosophila neuropeptide Capa: the ABCA neurons. Our data support the birth of the ABCA neurons from NB 5-3 in a cas temporal window in the abdominal segments A2–A4. Moreover, we show that the ABCA neuron has an ABCA-sibling cell which dies by apoptosis. Surprisingly, both cells are also generated in the abdominal segments A5–A7, although they undergo apoptosis before expressing Capa. In addition, we have performed a targeted genetic screen to identify players involved in ABCA specification. We have found that the ABCA fate requires zfh2, grain, Grunge and hedgehog genes. Finally, we show that the NB 5-3 generates other subtype of Capa-expressing cells (SECAs) in the third suboesophageal segment, which are born during a pdm/cas temporal window, and have different genetic requirements for their specification.This work was supported by a grant from the Spanish Ministerio de Ciencia e Innovación (BFU-2008-04683-C02-02 to L.T.)

Lineage-unrelated neurons generated in different temporal windows and expressing different combinatorial codes can converge in the activation of the same terminal differentiation gene

It is becoming increasingly clear that the activation of specific terminal differentiation genes during neural development is critically dependent upon the establishment of unique combinatorial transcription factor codes within distinct neural cell subtypes. However, it is still unclear to which extent these codes are shared by lineage-unrelated neurons expressing the same terminal differentiation genes. Additionally, it is not known if the activation of a specific terminal differentiation gene is restricted to cells born at a particular developmental time point. Here, we utilize the terminal differentiation gene FMRFa which is expressed by the Ap4 and SE2 neurons in the Drosophila ventral nerve cord, to explore these issues in depth. We find that the Ap4 and SE2 neurons are generated by different neural progenitors and use different combinatorial codes to activate FMRFa expression. Additionally, we find that the Ap4 and SE2 neurons are generated in different temporal gene expression windows. Extending the investigation to include a second Drosophila terminal differentiation gene, Leucokinin, we find similar results, suggesting that neurons generated by different progenitors might commonly use different transcription factor codes to activate the same terminal differentiation gene. Furthermore, these results imply that the activation of a particular terminal differentiation gene in temporally unrestricted.This work was supported by a grant from the Spanish Ministerio de Ciencia e Innovación (BFU-2008- 04683-C02-02 to L.T.)

Dachshund acts with Abdominal-B to trigger programmed cell death in the Drosophila central nervous system at the frontiers of Abd-B expression

A striking feature of the nervous system pertains to the appearance of different neural cell subtypes at different axial levels. Studies in the Drosophila central nervous system reveal that one mechanism underlying such segmental differences pertains to the segment-specific removal of cells by programmed cell death (PCD). One group of genes involved in segment-specific PCD is the Hox homeotic genes. However, while segment-specific PCD is highly precise, Hox gene expression is evident in gradients, raising the issue of how the Hox gene function is precisely gated to trigger PCD in specific segments at the outer limits of Hox expression. The Drosophila Va neurons are initially generated in all nerve cord segments but removed by PCD in posterior segments. Va PCD is triggered by the posteriorly expressed Hox gene Abdominal-B (Abd-B). However, Va PCD is highly reproducible despite exceedingly weak Abd-B expression in the anterior frontiers of its expression. Here, we found that the transcriptional cofactor Dachshund supports Abd-B-mediated PCD in its anterior domain. In vivo bimolecular fluorescence complementation analysis lends support to the idea that the Dachshund/Abd-B interplay may involve physical interactions. These findings provide an example of how combinatorial codes of transcription factors ensure precision in Hox-mediated PCD in specific segments at the outer limits of Hox expressionMinisterio de Ciencia y Educación, Grant/Award Number: PID2019-110952GB-I0