Before programs: The physical origination of multicellular forms

ABSTRACT By examining the formative role of physical processes in modern-day developmental systems, we infer that although such determinants are subject to constraints and rarely act in a “pure ” fashion, they are identical to processes generic to all viscoelastic, chemically excitable media, non-living as well as living. The processes considered are free diffusion, immiscible liquid behavior, oscillation and multistability of chemical state, reaction-diffusion coupling and mecha-nochemical responsivity. We suggest that such processes had freer reign at early stages in the history of multicellular life, when less evolution had occurred of genetic mechanisms for stabilization and entrenchment of functionally successful morphologies. From this we devise a hypothetical scenario for pattern formation and morphogenesis in the earliest metazoa. We show that the expected morphologies that would arise during this relatively unconstrained “physical” stage of evolution correspond to the hollow, multilayered and segmented morphotypes seen in the gastrulation stage embryos of modern-day metazoa as well as in Ediacaran fossil deposits of ~600 Ma. We suggest several ways in which organisms that were originally formed by predomi-nantly physical mechanisms could have evolved genetic mechanisms to perpetuate their mor-phologies

Integrated Analysis of Patterning, Morphogenesis, and Cell Divisions in Embryonic Development by in toto Imaging and Quantitative Cell Tracking

Patterning, morphogenesis, and cell divisions are distinct processes during development yet are concurrent and likely highly integrated. However, it has been challenging to investigate them as a whole. Recent advances in imaging and labeling tools make it possible to observe live tissues with high coverage and resolution. In this dissertation work, we developed a novel imaging platform that allowed us to fully capture the early neural tube formation process in live zebrafish embryos at cellular resolution. Importantly, these datasets allow us to reliably track single neural progenitors. These tracks carry information on the history of cell movement, shape change, division, and gene expression all together. By comparing tracks of different progenitor fates, we found they show a spatially noisy response to Sonic hedgehog (Shh) and become specified in a positionally mixed manner, in surprising contrast to the "French Flag" morphogen patterning model. Both cell movement and division contribute to cell mixing. In addition, we decoupled the temporal and genetic regulatory network (GRN) noises in Shh interpretation using tracks that carry both Shh signaling and cell fate reporters. Our tracks suggest that, after specification, progenitors undergo sorting to self-assemble a sharp pattern. Consistent with this hypothesis, we found ectopically induced progenitors move to correct locations. Furthermore, we show that proper adhesion is required for cell sorting to happen (Chapters 2 and 3). In the cleavage stage embryos, the cells on the surface undergo shape changes followed by lineage separation and differentiation. We quantitatively measured this morphogenesis process and tracked cell divisions. By applying a mathematical model we uncover a predictive, and perhaps general link between cell division orientation, mechanical interaction, and the morphogenetic behavior of the whole surface layer (Chapter 4). Finally, we discuss the concepts and tools of cell tracking including a multi-color cell labeling method we developed by modifying the "Brainbow" system (Chapter 5). Together this dissertation showcases the importance and promise of live observation based, quantitative and integrated analysis in our understanding of complex multi-cellular developmental processes

Study of genetic and phenotypic variability for adaptative traits in natural populations of Drosophila melanogaster

Si bien se ha progresado sustancialmente en la dilucidación de los factores fisiológicos y ambientales que determinan la variabilidad fenotípica en los caracteres adaptativos del desarrollo, se conoce poco acerca de la arquitectura genética de los mismos. El estudio de la arquitectura genética requiere identificar y caracterizar los genes que contribuyen a la expresión fenotípica de los caracteres así como los factores que afectan la variabilidad de los mismos, lo cual puede lograrse por diversos medios. En el presente trabajo se analizó la variabilidad fenotípica para distintos caracteres adaptativos del desarrollo (Tiempo de Desarrollo larval y pupal, Viabilidad larval y pupal, Altura de formación de pupas, sus plasticidades fenotípicas, Coeficientes de Variación Ambiental y la relación entre Tiempo de Desarrollo Larval y Pupal) en el organismo modelo Drosophila melanogaster a dos temperaturas de cría usando un panel de 40 líneas derivadas de una población natural. Con los datos genómicos correspondientes a estas líneas se obtuvieron 1186 SNPs y 923 genes candidatos que orquestarían la expresión de estos distintos caracteres durante la ontogenia. Algunos de estos SNPs o genes fueron pleiotrópicos. Los genes candidatos estarían principalmente implicados en morfogénesis de distintas estructuras anatómicas, metamorfosis, comportamientos de locomoción o alimentación y metabolismo, entre otras funciones biológicas; varios de ellos forman parte de importantes pathways o cascadas de señalización con papeles decisivos en el desarrollo. Mediante el uso de líneas mutagenizadas, algunos de los genes candidatos más significativos para los distintos caracteres fueron validados. Por otro lado, con el objetivo de caracterizar la variabilidad para estos caracteres en otras poblaciones naturales y relacionarla con variables geográficas, se generaron líneas isogénicas derivadas de poblaciones naturales de dos locaciones argentinas situadas a diferente altitud, midiéndose en ellas los mismos caracteres a dos temperaturas de cría. Las tres poblaciones analizadas presentaron amplia variabilidad fenotípica para todos los caracteres medidos, determinada por el genotipo, el ambiente y la interacción entre ambos factores. Se detectó un grado de canalización microambiental variable en los fenotipos, dependiendo tanto del genotipo como del ambiente de origen y el de medición; las líneas provenientes de la localidad de altura presentaron mayor canalización en los fenotipos a bajas temperaturas y viceversa. En las tres poblaciones se detectaron correlaciones significativas entre distintos caracteres, particularmente entre los caracteres larvales, y se comprobó un desacople entre los caracteres para los estadíos larval y pupal. En conjunto, nuestros resultados resaltan el papel de importantes procesos del desarrollo conectados e interdependientes subyaciendo a los caracteres medidos, demuestran la existencia de variabilidad genética afectando estos procesos y por lo tanto la expresión de los caracteres y su robustez (a nivel macro y microambiental), y destacan la importancia de las fuerzas selectivas que operan sobre las poblaciones naturales en el establecimiento de esta variabilidad.Although substantial progress has been made to elucidate the physiologic and environmental aspects underlying phenotypic variability for adaptive developmental traits, little is known about their genetic architecture. Its study requires identifying and characterizing the genes that affect the phenotypic expression of these traits as well as the factors affecting their variability, a task that can be achieved by different means. Here we analyze phenotypic variability for several developmental adaptive traits (Larval and Pupal Developmental Time, Larval and Pupal Viability, Pupation Height, their plasticities, Coefficients of Environmental Variance and the ratio of Larval/Pupal Developmental Time) in the model organism Drosophila melanogaster at two rearing temperatures, using a panel of 40 lines derived from a natural population. Using the genomic data from these lines we obtained 1186 SNPs and 923 candidate genes that would orchestrate the expression of these characters during ontogeny. Some of these SNPs or genes are pleiotropic. The candidates are mostly involved in the morphogenesis of different anatomical structures, metamorphosis, locomotion, feeding behavior and metabolism, among other biological functions; several of them take part in important pathways or signaling cascades with decisive roles in development. Through the use of mutagenized lines, some of the most significative candidates were validated. Besides, to assess the variability for these traits in other natural populations and relate it with geographic variables, we generated isogenic lines derived from two natural populations from Argentina collected in locations with differing altitudes. We measured the same traits on these lines at the two rearing temperatures. For the three populations, substantial phenotypic variability for all traits was found, which was affected by their genotype, the rearing environment and the interaction between both factors. A variable degree of microenvironmental canalization was detected for all phenotypes, depending on genotype as well as on the environment of origin and rearing temperature; lines from the Argentine highland population showed more canalized phenotypes when measured at lower temperatures and vice versa. For the three populations significant correlations between traits were detected, particularly between larval traits, and the uncoupling between larval and pupal traits was confirmed. To summarize, our results highlight the role of important and interdependent developmental processes underlying the traits here considered, demonstrate the existence of genetic variability affecting these processes and thus the expression of the traits and their macro and microenvironmental robustness, and draw attention to the importance of the selective forces operating over natural populations on the establishment of said variability.Fil: Petino Zappala, María Alejandra. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

CIMODE 2016: 3º Congresso Internacional de Moda e Design: proceedings

O CIMODE 2016 é o terceiro Congresso Internacional de Moda e Design, a decorrer de 9 a 12 de maio de 2016 na cidade de Buenos Aires, subordinado ao tema : EM--‐TRAMAS. A presente edição é organizada pela Faculdade de Arquitetura, Desenho e Urbanismo da Universidade de Buenos Aires, em conjunto com o Departamento de Engenharia Têxtil da Universidade do Minho e com a ABEPEM – Associação Brasileira de Estudos e Pesquisa em Moda.info:eu-repo/semantics/publishedVersio