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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
201

Caractérisation des gènes AP2/ERF impliqués dans le développement chez Hevea brasiliensis / Characterization of the AP2/ERF genes involved in development of Hevea brasiliensis

Piyatrakul, Piyanuch 13 December 2013 (has links)
Hevea brasiliensis est une culture industrielle majeure pour la production de caoutchouc naturel (CN). La stimulation par l'éthéphon, un libérateur d'éthylène, est utilisée pour augmenter la production de latex en prolongeant son écoulement et en stimulant le métabolisme pour la régénération du latex. Cependant, le mécanisme d'action de l'éthylène n'est pas clairement élucidé chez l'hévéa. L'éthylène est un signal important qui régule le développement des plantes. Les facteurs de transcription AP2/ERF, et plus particulièrement les Ethylene Response Factors, jouent un rôle crucial dans le développement et la réponse aux stress biotiques et abiotiques chez les plantes. La production d'éthylène et sa signalisation sont aussi importantes en embryogenèse somatique et tout spécialement chez les espèces récalcitrantes à la culture in vitro.Dans cette étude, le transcriptome de référence a été amélioré par addition des fragments de séquence d'ARN issus de tissus reproducteurs lors d'un nouvel assemblage. Les 30.342 contigs ont été annotés par la base de données Gene Ontology. L'analyse des facteurs de transcription a permis d'identifier 2.448 contigs qui ont été classés en 58 familles de facteurs de transcription. Six pourcents de ces facteurs de transcription correspondent aux membres de la superfamille des AP2/ERF. L'accumulation de transcrits des gènes AP2/ERF a été analysée au cours du processus d'embryogenèse somatique chez des lignées de cal avec différents potentiels de régénération et dans différents tissus végétatifs et reproducteurs. L'analyse de l'abondance relative de transcrits dans les différents tissus montre que les ERFs des groupes I, VII et VIII sont fortement présents à tous les stades de l'embryogenèse somatique et dans les tissus immatures et matures de fleurs males et femelle, d'embryons zygotiques, de feuilles, d'écorce et de latex. Quarante gènes AP2/ERF représentent des marqueurs d'expression génique pour le potentiel de régénération de plantes de lignées de cal à différents stades du processus d'embryogenèse somatique. Quatorze marqueurs d'expression génique permettent même de prédire la capacité de régénération dès le stade de multiplication du cal. Cinquante-neuf marqueurs d'expression géniques sont spécifiquement exprimés dans les différents tissus de l'hévéa, et plusieurs AP2/ERFs ont les transcrits fortement accumulés dans le latex. La plupart des marqueurs de l'expression génique du latex appartient aux ERF du groupe VII. Les ERFs de ce groupe ont un motif conservé en N-terminal (MCGGAII), lequel est impliqué dans la voie N-end rule. Les analyses de localisation subcellulaire et de transactivation suggèrent que ces gènes HbERF-VII codent pour des facteurs de transcription fonctionnels potentiellement impliqués dans la réponse à l'hypoxie dans le latex. / Hevea brasiliensis is the major industrial crop for natural rubber (NR) production. Ethephon stimulation, an ethylene releaser, is used for increasing latex production by prolonging latex flow and stimulating the metabolism required for the latex regeneration. However, the mechanism of ethylene action is not clearly elucidated in this species. Ethylene is an important signal regulating the plant development. AP2/ERF transcription factors, and especially Ethylene-Response Factors, play a crucial role in plant development and response to biotic and abiotic stresses. Ethylene production and signalling are also important to somatic embryogenesis, especially for species that are recalcitrant in in vitro culture.In this study, a comprehensive Hevea transcriptome was improved using additional RNA reads from reproductive tissues in a new assembly. The 30,342 contigs were annotated in the Gene Ontology database. The analysis of transcription factors led to 2,448 contigs being identified, which were classed in 58 transcription factor families. Six percent of the transcription factors corresponded to members from the AP2/ERF superfamily. The transcript accumulation of AP2/ERF genes was analyzed during somatic embryogenesis for callus lines with different regeneration potential and in various vegetative and reproductive tissue of Hevea. The relative transcript abundance were studied and showed that ERFs from group I, VII and VIII were abundant at all stages of the somatic embryogenesis as well as, in both immature and mature male and female flowers, zygotic embryos, leaf, bark and latex. Forty genes were identified as expression marker for callus with different plant regeneration potential regeneration capacity. Interestingly, fourteen expression marker genes were found that be able to predict the regeneration capacity of callus at proliferating calli, the early stage of somatic embryogenesis process. Fifty-nine expression marker genes were found in the various plant tissues. Several AP2/ERF genes were shown highly transcript accumulation in latex and were assigned as latex expression marker genes. Almost of latex expression marker genes belong to the ERF group VII. Base on conserved motif analysis showed this ERF group contained the conserved N-terminal motif (MCGGAII) involved in the N-end rule pathway. Subcellular localization and transactivation analyses suggested that HbERF-VII candidate genes encoded functional transcription factors.
202

A sinalização pelo ácido retinóico e a origem evolutiva das câmaras cardíacas. / Retinoic acid signaling and the evolutionary origins of cardiac chambers.

Marcos Sawada Simões Costa 17 April 2009 (has links)
Nos últimos anos, nós propusemos um modelo de duas etapas para a padronização antero-posterior do coração. Ácido retinóico (AR) produzido pela enzima RALDH2 induz o destino sino atrial nos precursores cardíacos posteriores. Subsequentemente, estes precursores adquirem a capacidade de expressar RALDH2, formando uma onda caudo-rostral desta enzima. A nossa hipótese é que esta onda surgiu nos para padronizar as células precursoras da bomba circulatória ancestral em regiões de influxo e efluxo, resultando na origem das câmaras cardíacas. Para testar se a onda cauro-rostral é ancestral nos vertebrados, nós mapeamos a expressão de RALDH2 em relação ao campo cardíaco em anfíbios, vertebrados basais e no cordado invertebrado anfioxo. Nossos dados sugerem que o modelo de duas etapas está presente em anfíbios e peixes. Clonagem do gene RALDH em lampréias indica presença de AR no campo cardíaco. Em anfioxo, a caracterização do padrão de expressão do ortólogo da RALDH2 revela ausência da onda caudo-rostral. Nossos resultados sugerem que a onda caudo-rostral de RALDH2 foi cooptada nos vertebrados para padronizar o campo cardíaco no eixo AP, o que corrobora a hipotése de que este mecanismo foi importante na origem evolutiva das câmaras cardíacas. / In the last years, we have proposed a 2-step model for the establishment of cardiac chamber identities. Retinoic acid (RA) produced by its synthetic enzyme RALDH2, induces an atrial fate in posterior cardiac precursors of amniote embryos. Subsequently, a RALDH2 caudorostral wave engulfs posterior precursors. Our hypothesis is that this wave evolved in vertebrates to pattern an ancestral circulatory pump into AP fields, which were later fashioned into cardiac chambers. To test whether the wave is an ancestral or derived feature of amniotes, we mapped expression of RALDH2 in relation to the cardiac field in amphibians, basal vertebrates and the amphioxus. Our data suggests RA signaling patterns amphibian and piscine hearts. Cloning of RALDH in lampreys shows that RA synthesis takes place in the heart field. In the amphioxus, cloning of RALDH reveals a vertebrate-like expression pattern, although the RALDH2 wave is absent. Our results support the hypothesis that the caudorostral wave of RALDH2 was coopted to pattern the vertebrate cardiac field. This supports the hypothesis that the caudorostral wave of RALDH2 was an important player in the evolutionary origin of the cardiac chambers.
203

Ácido salicílico como sinalizador durante a embriogênese de Araucaria angustifolia (Bert.) O. Kuntze / Salicylic acid as a marker during embryogenesis in Araucaria angustifolia (Bert.) O. Kuntze

Caroline Arcanjo Bueno 10 November 2014 (has links)
A Araucaria angustifólia é uma conífera nativa do Brasil que apresenta sementes recalcitrantes. Devido a sua importância econômica, foi intensamente explorada ao longo dos anos, encontrando-se atualmente classificada como espécie em perigo crítico de extinção pela International Union for Conservation of Nature. A embriogênese somática apresenta-se como uma ferramenta biotecnológica de grande valia na propagação de espécies recalcitrantes e de difícil propagação, com aplicação em programas de conservação, reflorestamento, e melhoramento genético vegetal. Estudos comparativos dos processos de embriogênese somática e zigótica têm permitido o conhecimento dos fatores bioquímicos, fisiológicos e genéticos que controlam o desenvolvimento do embrião, e o estabelecimento as condições artificiais para o correto desenvolvimento embrionário in vitro. O objetivo deste trabalho foi estudar a participação do ácido salicílico como sinalizador do processo de embriogênese zigótica e somática em A. angustifólia. Para tanto foi determinado o conteúdo de ácido salicílico livre e conjugado ao longo da embriogênese zigótica, e o efeito de sua suplementação em culturas embriogênicas com diferentes potenciais para a maturação. Para a embriogênese somática, a presença do ácido salicílico foi correlacionada com a geração de óxido nítrico e espécies reativas de oxigênio , e com a expressão do gene \"Somatic Embryogenesis Receptor Kinase\" (AaSERK). Os resultados obtidos demonstram que: a) ocorre um maior conteúdo de ácido salicílico na forma livre e conjugada nas etapas iniciais da embriogênese zigótica; b) a suplementação de ácido salicílico, nas concentrações de 0,5 a 2 mM, inibiram a indução de culturas embriogênicas; c) culturas embriogênicas incubadas em ácido salicílico apresentaram redução da síntese endógena de espécies reativas de oxigênio e aumento no conteúdo de óxido nítrico; d) a redução de espécies reativas de oxigênio indicou uma relação dose dependente com o ácido salicílico; e) a adição de um doador de óxido nítrico e um sequestrador inibiram a produção de espécies reativas de oxigênio; f) a expressão do gene AaSERK atingiu o maior nível no período de quatro horas de incubação em 0,1 mM de AS / Araucaria angustifolia is a conifer native of Brazil with recalcitrant seeds. Due to its economic importance, the exploration has been extensively over the years, currently this specie is classified as critically endangered by the International Union for Conservation of Nature. Somatic embryogenesis is presented as a biotechnological tool of great value in the propagation of recalcitrant species and difficult to spread, with applications in conservation, reforestation programs, and plant breeding. Comparative studies of the processes of zygotic and somatic embryogenesis has allowed the knowledge of biochemical, physiological and genetic factors that control embryo development, and the establishment artificial conditions for proper embryonic development in vitro. The objective of this work was to study the role of salicylic acid as a marker of zygotic embryogenesis and somatic process in A. angustifolia. Thus, we determined the content of free salicylic acid and conjugated along the zygotic embryogenesis, and the effect of their supplementation with different potential embryogenic cultures for maturation. For somatic embryogenesis, the presence of salicylic acid was correlated with the generation of nitric oxide, reactive oxygen species and in the gene expression \"Somatic embryogenesis Receptor Kinase\" (AaSERK). The results show that: a) there is an increased content of salicylic acid in free and conjugated form in the initial stages of zygotic embryogenesis; b) salicylic acid supplementation, in concentrations from 0.5 to 2 mM, inhibited the induction of embryogenic cultures; c) embryos incubated in salicylic acid decreased endogenous synthesis of reactive oxygen species and increase in content of nitric oxide; d) the reduction of reactive oxygen species indicated a dose-dependent relationship with salicylic acid; e) the addition of a nitric oxide donor and a kidnapper inhibited the production of reactive oxygen species; f) the expression of the gene AaSERK reached the highest level in four hours of incubation in 0.1 mM AS
204

Reverse-time inference of biological dynamics

Lenner, Nicolas 13 November 2019 (has links)
No description available.
205

Investigating the localization mechanism of Bsg25D mRNA in Drosophila melanogaster

Velupillai, Sinduja 04 1900 (has links)
Le transport subcellulaire et la traduction localisée des molécules d'ARNm semble être un processus très répandu et important pour contrôler la distribution asymétrique des protéines dans les cellules. L’ARNm, Bsg25D, connu pour se localiser aux centrosomes et aux microtubules astraux dans les embryons de drosophile au cours des premiers événements d'embryogenèse, a été sélectionné pour déterminer le rôle et l'importance du ciblage de l'ARNm à l'appareil mitotique lors de la division cellulaire. La localisation de Bsg25D aux centrosomes dans les embryons de drosophile est conservée entre espèces telles que D. melanogaster, D. simulans et D. yakuba. Bsg25D encode une protéine qui est étroitement liée à la Ninein (Nin) et à la Ninein-like protein (Nlp), deux protéines associées aux centrosomes présentes dans les cellules mammifères. L’analyse structure-fonction démontre que la région codante et la région 3’UTR de Bsg25D sont nécessaires pour son ciblage. Ceci suggère qu’un élément de régulation en cis, qui favorise sa localisation se situe dans la région codante + 3’UTR. / The subcellular transport and localized translation of mRNA molecules is emerging as a highly prevalent and important process for controlling asymmetric protein distribution in cells. A candidate mRNA, Bsg25D, known to localize to centrosomes and astral microtubules in Drosophila embryos during early events of embryogenesis, was selected to determine the role and importance of mRNA targeting to the mitotic apparatus during cell division. The localization of Bsg25D to centrosomes in Drosophila embryos is conserved between species such as D. melanogaster, D. simulans and D. yakuba. Bsg25D encodes a protein closely related to centrosome-associated proteins Ninein (Nin) and Ninein-like protein (Nlp) in mammalian cells. Structure function analysis revealed that the coding and 3’UTR of Bsg25D are necessary for its targeting pattern, suggesting that a cis-regulatory motif that drives its localization, is in the coding + 3’ UTR region.
206

Jamming in Embryogenesis and Cancer Progression

Blauth, Eliane, Kubitschke, Hans, Gottheil, Pablo, Grosser, Steffen, Käs, Josef A. 30 March 2023 (has links)
The ability of tissues and cells to move and rearrange is central to a broad range of diverse biological processes such as tissue remodeling and rearrangement in embryogenesis, cell migration in wound healing, or cancer progression. These processes are linked to a solidlike to fluid-like transition, also known as unjamming transition, a not rigorously defined framework that describes switching between a stable, resting state and an active, moving state. Various mechanisms, that is, proliferation and motility, are critical drivers for the (un) jamming transition on the cellular scale. However, beyond the scope of these fundamental mechanisms of cells, a unifying understanding remains to be established. During embryogenesis, the proliferation rate of cells is high, and the number density is continuously increasing, which indicates number-density-driven jamming. In contrast, cells have to unjam in tissues that are already densely packed during tumor progression, pointing toward a shape-driven unjamming transition. Here, we review recent investigations of jamming transitions during embryogenesis and cancer progression and pursue the question of how they might be interlinked. We discuss the role of density and shape during the jamming transition and the different biological factors driving it.
207

Developmental Regulation of Prion Expression in Cattle and Mouse Embryonic Stem Cells

Peralta, Oscar A. 03 September 2008 (has links)
The host encoded cellular prion protein (PrPC) is an N-linked glycoprotein tethered to the cell membrane by a glycophosphatidylinositol (GPI) anchor. Under certain conditions, PrPC can undergo conversion into a conformationally-altered isoform (PrPSc) widely believed to be the pathogenic agent of transmissible spongiform encephalopathies (TSEs). Thus, tissues expressing PrPC are potential sites for conversion of PrPSc during TSE pathogenesis. Although much is known about the role of PrPSc in prion diseases, the normal function of PrPC is poorly understood. Lines of mice and cattle in which PrPC has been ablated by gene knockout show no major phenotypical alterations other than resistance to TSE infection. However, recent reports using Prnp-null mouse models have suggested the participation of PrPC in neural stem/progenitor cell proliferation and differentiation. The first objective in our study was to map the expression of PrPC in twenty six somatic and reproductive tissues in ruminants. Our second objective was to characterize the ontogeny of PrPC expression during bovine embryonic and early fetal development. Finally, we used a mouse embryonic stem cell (mESC) model to study the potential role of PrPC during neurogenesis. In adult tissues, intense expression of PrPC was detected in the central nervous system (CNS), thymus and testes, whereas the liver, striated muscle and female reproductive tissues showed the lowest expression. We observed that PrPC was associated with tissues undergoing cellular differentiation including spermatogenesis, lymphocyte activation and hair follicle regeneration. Analyses in bovine embryos and fetuses indicated peaks in expression of PrPC at days 4 and 18 post-fertilization, stages associated with the maternal-zygote transition and the maternal recognition of pregnancy and initiation of placental attachment, respectively. Later in development, PrPC was expressed in the CNS where it was localized in mature neurons of the neuroepithelium and emerging neural trunks. Based on these observations, we hypothesized that PrPC was involved in neurogenesis. We tested this hypothesis in a murine embryonic stem cell model (mESC). mESC were induced to form embryoid bodies (EBs) by placing them in suspension culture under differentiating conditions and allowed to differentiate in vitro for 20 days. We detected increasing levels of PrPC starting on day 12 (8.21- fold higher vs. day 0; P < 0.05) and continuing until day 20 (20.77-fold higher vs. day 0; P < 0.05). PrPC expression was negatively correlated with pluripotency marker Oct-4 (r= -0.85) confirming that mESC had indeed differentiated. To provide a more robust system for assessing the role of PrPC in neural differentiation, mESC were cultured with or without retinoic acid (RA) to encourage differentiation into neural lineages. Induction of EBs with retinoic acid (RA) resulted in an earlier up-regulation of PrPC and nestin (day 12 vs. day 16; P < 0.05). In addition, immunofluorescence studies indicated co-expression of PrPC and nestin in the same cells. The results of these experiments suggested a temporal link between PrPC expression and expression of nestin, a marker of neural progenitor cells. We next tested whether PrPC was involved in RA-enhanced neural differentiation from mESC using a PrPC knockdown model. Plasmid vectors designed to express either a PrP-targeted shRNA or scrambled, control shRNA were transfected into mESC. Stable transfectants were selected under G418 and cloned. PrP-targeted and control shRNA clones, as well as wild-type mESC, were differentiated in presence of RA and sampled as above. PrPC expression was knocked down in PrP-targeted shRNA cultures between days 12 and 20 (62.2 % average reduction vs. scrambled shRNA controls). Nestin expression was reduced at days 16 and 20 in PrPC knockdown cells (61.3% and 70.7%, respectively vs. scrambled shRNA controls). These results provide evidence that PrPC plays a role in the neural differentiation at a point up-stream from the stages at which nestin is expressed. In conclusion, the widely distributed expression of PrPC in ruminant tissues suggests an important biological role for this protein. In the present work we have provided evidence for the participation of PrPC in the differentiation of mESC along the neurogenic pathway. / Ph. D.
208

Elucidating the Function of Krüppel Homolog 1 (Kr-h1) Associated Proteins (KAPs) in Aedes aegypti Reproduction Through RNA Interference-Mediated Downregulation

Zhang, Liyan 15 July 2024 (has links)
The transcription factor Krüppel homolog 1 (Kr-h1) is crucial in multiple reproductive processes of Aedes aegypti mosquitoes, including previtellogenesis, vitellogenesis, and oogenesis. This study explores the interaction between Kr-h1 and its potential associated proteins (KAPs), with a specific focus on the dimerization partner (DP-1), and how this interaction regulates gene expression pathways critical for mosquito reproduction. Utilizing RNA interference (RNAi), the research identifies DP-1 as a significant regulator of follicle growth post-eclosion (PE), highlighting its vital role in the mosquito reproductive regulatory pathway. The experimental approach included RNAi-mediated knockdown of DP-1, accompanied by evaluations using quantitative PCR (qPCR), Western blotting (WB), co-immunoprecipitation (Co-IP), follicle length measurement, and egg counting to assess the role of DP-1 in reproductive functions. For the first time, the inhibition of DP-1 expression was found to significantly impede A. aegypti follicular development. The elucidation of the mechanistic roles of Kr-h1 and DP-1 provides valuable insights that could lead to innovative strategies for mosquito population control and effective disease vector management. / Master of Science in Life Sciences / Mosquitoes can spread serious insect-borne diseases such as dengue, Zika, and malaria, etc. These diseases can infect hundreds of millions of individual and cause around a million of death annually. This study focuses on a specific mosquito species, Aedes aegypti, which is a major carrier of these diseases. To manage their populations and reduce the spread of these diseases, scientists are constantly seeking new methods to control their reproduction. Chemical insecticides are one of the most efficient and widely used strategies. However, these insecticides face significant challenges, including the development of resistance in mosquito populations and the potential damage to non-target species to affect the ecosystem. To address this issue, the development of new insecticides is crucial. We can identify new targets to pave the way to research novel effective insecticides. Inside mosquitoes, there are various proteins that help control their ability to reproduce. One of these proteins is called Krüppel homolog 1 (Kr-h1). Kr-h1 plays a crucial role in the development and reproductive processes of mosquitoes. Our research looked at how Kr-h1 interacts with other types of protein to control mosquito reproduction. Through various experiments, including gene expression analysis and protein studies, we found that DP-1 is essential for the proper development of mosquito eggs. This insight helps us understand more about the biological processes and hormonal pathways during mosquito reproduction, therefore provide greater opportunity to develop insecticides to reduce their populations and the spread of the diseases they carry.
209

Multidisciplinary study of the role of calcium in plant in vitro embryogenesis

Calabuig Serna, Antonio 06 September 2023 (has links)
[ES] El calcio (Ca2+) es un catión esencial que juega un papel fundamental en todos los organismos vivos. Desde el punto de vista funcional, el Ca2+ actúa como un segundo mensajero que regula distintos procesos celulares. Trabajos anteriores indican que la señalización mediante Ca2+ podría estar implicada en las primeras etapas de la inducción de la embriogénesis in vitro de las plantas, pero el verdadero papel del Ca2+ en este proceso es aún desconocido. Por eso, el principal objetivo de la presente Tesis es el estudio del papel del Ca2+ en la embriogénesis in vitro mediante dos sistemas in vitro: la embriogénesis somática y la embriogénesis de microsporas. Para determinar la importancia de la homeostasis del Ca2+ en la inducción de la embriogénesis y las dinámicas de los niveles de Ca2+ durante la inducción y el establecimiento de embriones somáticos y derivados de microsporas, se utilizaron tratamientos químicos y se detectaron los niveles de Ca2+ mediante sondas fluorescentes y sensores cameleon codificados genéticamente, visualizados con microscopía fluorescente y confocal. Observamos que el aumento de Ca2+ es un marcador temprano en la inducción de la embriogénesis in vitro y que los niveles de Ca2+ durante la embriogénesis in vitro son dinámicos en todos los sistemas estudiados. Además, las oscilaciones en los niveles de Ca2+ podrían estar relacionadas con los procesos de diferenciación que ocurren en las células inducidas una vez une el Ca2+ a la calmodulina. Mostramos que un aumento de Ca2+ dentro de un rango definido de concentración tiene un efecto positivo, dependiendo del sistema, en la producción de embriones, siendo más sensibles aquellos sistemas basados en suspensiones de células aisladas que aquellos que usan tejidos como explantes. Finalmente, estudiamos el papel de la calosa durante la embriogénesis somática, observando que la inhibición de la deposición de calosa impide el desarrollo embrionario, lo que sugiere una relación entre la formación de una barrera de calosa y el establecimiento de la identidad embrionaria en las células somáticas. / [CAT] El calci (Ca2+) és un catió essencial que juga un paper fonamental en tots els organismes vius. Des del punt de vista funcional, el Ca2+ actua com a un segon missatger que regula diferents processos cel·lulars. Treballs anteriors indiquen que la senyalització mitjançant el Ca2+ podria estar implicada en les primeres etapes de la inducció de l'embriogènesi in vitro de les plantes, però el paper real del Ca2+ en aquest procés encara és desconegut. Per això, el principal objectiu de la present Tesi és l'estudi del paper del Ca2+ en l'embriogènesi in vitro mitjançant dos sistemes in vitro: l'embriogènesi somàtica i l'embriogènesi de micròspores. Per tal de determinar la importància de l'homeòstasi del Ca2+ en la inducció de l'embriogènesi i les dinàmiques dels nivells de Ca2+ durant la inducció i l'establiment d'embrions somàtics i derivats de micròspores, es van utilitzar tractaments químics i es van detectar els nivells de Ca2+ mitjançant sondes fluorescents i sensors de cameleon codificats genèticament, visualitzats amb microscòpia fluorescent i confocal. Vam observar que l'augment de Ca2+ és un marcador primerenc en la inducció de l'embriogènesi in vitro i que els nivells de Ca2+ durant l'embriogènesi in vitro són dinàmics en tots els sistemes estudiats. A més, les oscil·lacions en els nivells de Ca2+ podrien estar relacionades amb els processos de diferenciació que tenen lloc en les cèl·lules induïdes una vegada uneix el Ca2+ a la calmodulina. Vam mostrar que un augment de Ca2+ dins d'un rang definit de concentració té un efecte positiu, depenent del sistema, en la producció d'embrions, essent més sensibles aquells sistemes basats en suspensions de cèl·lules aïllades que aquells que usen teixits com a explants. Finalment, vam estudiar el paper de la cal·losa durant l'embriogènesi somàtica, i vam observar que la inhibició de la deposició de cal·losa impedeix el desenvolupament embrionari, la qual cosa suggereix una relació entre la formació d'una barrera de cal·losa i l'establiment de la identitat embrionària en les cèl·lules somàtiques. / [EN] Calcium (Ca2+) is an essential cation that plays fundamental roles in all living organisms. From a functional point of view, Ca2+ acts as a second messenger that regulates different cellular processes. Previous works point to the fact that Ca2+ signaling may be involved in the early stages of induction of in vitro plant embryogenesis, but the actual role of Ca2+ in this process remained unveiled. Thus, the main goal of the present Thesis is to study the role of Ca2+ in in vitro embryogenesis using two in vitro systems: somatic embryogenesis and microspore embryogenesis. Chemical treatments and detection of Ca2+ with fluorescent probes and genetically-encoded cameleon sensors imaged by fluorescence and confocal microscopy were performed to determine the importance of Ca2+ homeostasis for induction of embryogenesis and the dynamics of Ca2+ levels during the induction and establishment of somatic and microspore-derived embryos. We observed that Ca2+ increase is an early marker of induction of in vitro embryogenesis and Ca2+ levels during in vitro embryogenesis are dynamic in all the systems we studied. Moreover, Ca2+ oscillations might be related to the differentiation processes that take place in the induced cells upon binding to calmodulin. We showed that Ca2+ increase within a defined range has system-specific positive effects in embryo yield, being more sensitive those systems using isolated cell suspensions rather than those using tissues as explants. Finally, we studied the role of callose during somatic embryogenesis, and we observed that inhibiting callose deposition prevents embryo development, which suggests a relationship between the formation of a callose barrier and the establishment of embryo identity in somatic cells. / Calabuig Serna, A. (2023). Multidisciplinary study of the role of calcium in plant in vitro embryogenesis [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/196022
210

Größenegulation der Augenanlage von Xenopus laevis durch Inhibition von Hedgehog-, Fgf- und Wnt-Signalen / size-regulation of the Xenopus laevis eye anlage by inhibition of Hedgehog-, Fgf- and Wnt-signals

Cornesse, Yvonne 05 November 2003 (has links)
No description available.

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