O histologista espanhol Santiago Ramón y Cajal participou do processo de restauração e institucionalização da Ciência Espanhola no final do século XIX e início do século XX. Em 1889, Ramón y Cajal demostrou à comunidade científica que o tecido nervoso é composto por células individuais, em contraposição à teoria do reticularismo vigente à época. Sua contribuição foi importante para os estudos histológicos e para a criação da área que depois viria a ser chamada Neurociência. O mérito de seu trabalho investigativo foi reconhecido com o prêmio Nobel de Fisiologia ou Medicina em 1906. Seu prestígio internacional impulsionou a investigação científica espanhola em diversas aéreas, especialmente na de Ciências da Vida, e o levou à direção da principal agência pública de fomento à pesquisa, a Junta para Ampliação dos Estudos e Investigações Científicas. Este trabalho tem o objetivo de analisar a participação e a influência de Ramón y Cajal na formulação de políticas de amparo à produção científica na Espanha, na formação de pesquisadores e no consequente avanço do conhecimento ocorrido no país no período indicado / The Spanish histologist Santiago Ramón y Cajal was a fundamental actor of the restoration and institutionalization of science in Spain in late 19th and early 20th centuries. In 1889, Ramón y Cajal demonstrated to the world scientific community that the nervous system is composed of individual cells, in contrast to the theory of reticularism in force at the time. His contribution was important to the histological studies of the brain and to the creation of what was to become neuroscience. The merit of his investigative was recognized with the Nobel Prize in Physiology or Medicine in 1906. His international prestige boosted many fields of Spanish science, specifically life sciences, and led him to become the director of the main public science funding agency in the country, the so called the Board for Expansion of Scientific Studies and Research. This work aims to analyze the participation and the influence of Ramón y Cajal in the formulation of policies to support the Spanish scientific production, in the training of researchers and in the consequent advancement of the knowledge in Spain in the mentioned period

Santiago Ramon y Cajal’s lifelong pursuit of understanding the intricate cell types in the nervous system ignited a pivotal inquiry in neurobiology. Despite advancements, the fundamental question persists: How does the human brain generate its diverse neuronal cell types? While progress has been made, the mechanisms governing neuronal diversity during brain development remain elusive. Numerous transcription factors and their regulatory mechanisms await elucidation, posing a formidable challenge due to the complexity of the task. The nematode Caenorhabditis elegans serves as an ideal model organism for investigating neuronal fate specification, owing to its small size, rapid generation time, transparency, and well-annotated genome. This dissertation focuses on the pharyngeal nervous system of C. elegans, comprised of only 20 neurons delineated into 14 distinct types. This simplicity enables detailed analyses of neuronal specifications within a largely autonomous circuit. This study employs two main approaches: a candidate gene analysis and an unbiased forward genetic screen. Through expression analysis in the laboratory, several homeodomain transcription factors were identified in pharyngeal neurons. Subsequent mutant analysis of these candidate genes tested their roles in specifying the pharyngeal nervous system. Additionally, this research explored the shifts in homeotic identity between pharyngeal neurons governed by these transcription factors. The forward genetic screen led to the discovery that the chd-7 chromatin regulatory factor plays an essential role in regulating I2 neuronal identity. These insights deepen our understanding of neuronal fate specification and suggest broader implications for understanding complex neural systems.