Resumo A região Neotropical, detentora da maior riqueza de espécies no globo, ocorre do México Central ao sul do Brasil. Neste trabalho, buscamos sumarizar as principais informações disponíveis na literatura que caracterizam os biomas neotropicais de Florestas Sazonalmente Seca (FTSS), Chaco e Savanas. Revisamos hipóteses biogeográficas concernentes a esses ambientes que buscam explicar sua dinâmica histórica. Nosso objetivo é oferecer uma caracterização desses biomas como etapa principal para o entendimento das principais hipóteses biogeográficas a eles associadas. Ainda que comporte como um cenário atraente para pesquisa, as espécies neotropicais são pouco estudas, sendo questões referentes a seus aspectos ecológicos, origem, história evolutiva e manutenção da elevada biodiversidade desconhecidas ou, ainda, pouco compreendidas. Embora, nossa revisão apresente pesquisas com diferentes pontos de vista quanto à dinâmica biogeográfica das formações vegetais, há consenso de que é produto de complexa interação entre os processos históricos, ecológicos e biológicos. Os estudos em biodiversidade de regiões ameaçadas, como os Neotrópicos, são norteadores para simulações e previsões de impactos, planos e estratégias de pesquisa.

Abstract The Neotropical region holds the largest species richness in the globe, occurring from Central Mexico to southern of Brazil. In this paper, we aim to summarize the main information available in the literature that characterizes the Neotropical biomes of Seasonally Dry Forests (SDF), Chaco and Savannas. Here we surveyed and reviewed biogeographic hypotheses concerning these environments that seek to explain their historical dynamics. Our goal is to offer a characterization of these biomes as a major step towards the understanding of the main hypotheses biogeographical associated with them. Although it supports an attractive scenario for research, Neotropical species are poorly studied, and questions concerning their ecological aspects, origin, evolutionary history and maintenance of the high biodiversity are unknown or even little understood. Although our review presents researches with different points of view regarding the biogeographic dynamics of vegetation formations, there is a consensus of being the product of a complex interaction between the historical, ecological and biological processes. Biodiversity studies of threatened regions, such as the Neotropic, are guidance for simulations and impacts predictions, for plans and research strategies.

The verification of the acute effects of ethanol on the midbrain, which neurons are mainly formed in E14, will ratify if the acute effects of ethanol are associated, in terms of prevalence, to the date of birth of neurons in certain regions of the brain. The aim of this study was to determine the effects of acute exposure to ethanol on the neuronal density of the midbrain and to associate these results with acute effects of ethanol in other regions of the brain under the same conditions. The rats were treated with intraperitoneal ethanol during one day (E12) and 1h after the last ethanol injection was applied to BrdU. The animals were sacrificed; the brains were removed and sectioned. The sections were treated with DAB for the BrdU revelation, the slides were stained with safranin for one group and another group was stained with H & E. The effects of acute injection of ethanol in E12 on the midbrain were not detected in this study. Data from literature suggest that the deleterious action of acute ethanol consumption only occur if the drug is injected at times near the beginning of the migration of neurons in that particular region of the brain.

La verificación de los efectos agudos del etanol sobre el mesencéfalo, cuyas neuronas se forman principalmente en la E14, puede ratificar si los efectos agudos del etanol están asociados, en términos de prevalencia, a la fecha de nacimiento de neuronas en ciertas regiones del cerebro. El objetivo de este estudio fue determinar los efectos de la exposición aguda al etanol sobre la densidad neuronal del mesencéfalo y asociar estos resultados con los efectos agudos de etanol en otras regiones del cerebro bajo las mismas condiciones. Las ratas fueron tratadas con etanol intraperitoneal durante un día (E12) y 1h después de la última inyección de etanol fue aplicado BrdU. Los animales fueron sacrificados, los cerebros fueron removidos y seccionados. Las secciones fueron tratados con DAB para la revelación de BrdU, las secciones fueron teñidas con safranina para un grupo y otro grupo se tiñeron con H&E. Los efectos agudos de la inyección de etanol en E12 sobre el mesencéfalo no fueron detectados en este estudio. Los datos de la literatura sugieren que los efectos deletéreos del consumo agudo de etanol sólo se producen si la droga se inyecta en etapas cercanas al comienzo de la migración de las neuronas en esa región particular del cerebro.