Opposing effects of ecdysone signaling regulate neuroblast proliferation to ensure coordination of brain and organism development.

Growth regulation must be robust to ensure correct final size, but also adaptative to adjust to less favorable environmental conditions. Developmental coordination between whole-organism and the brain is particularly important, as the brain is a critical organ with little adaptability. Brain growth mainly depends on neural stem cell (NSC) proliferation to generate differentiated neural cells, it is however unclear how organism developmental progression is coordinated with NSCs. Here we demonstrate that the steroid hormone ecdysone plays a multi-step, stage specific role in regulating Drosophila NSCs, the neuroblasts. We used animals that are unable to synthesize ecdysone, to show that the developmental milestone called "critical weight peak", the peak that informs the body has reached minimum viable weight to survive metamorphosis, acts a checkpoint necessary to set neuroblast cell cycle pace during larval neurogenesis. The peaks of ecdysone that occur post-critical weight are no longer required to maintain neuroblast division rate. We additionally show that in a second stage, at the onset of pupariation, ecdysone is instead required to trigger neuroblast's proliferation exit and consequently the end of neurogenesis. We demonstrate that, without this signal from ecdysone, neuroblasts lose their ability to exit proliferation. Interestingly, although these neuroblasts proliferate for a longer period, the number of differentiated neurons is smaller compared to wild-type brains, suggesting a role for ecdysone in neuron maintenance. Our study provides insights into how neural stem cells coordinate their division rate with the pace of body growth, identifying a novel coordination mechanism between animal development and NSC proliferation.

String/Cdc25 phosphatase is a suppressor of Tau-associated neurodegeneration.

Tau pathology is defined by the intracellular accumulation of abnormally phosphorylated Tau (MAPT) and is prevalent in several neurodegenerative disorders. The identification of modulators of Tau abnormal phosphorylation and aggregation is key to understanding disease progression and developing targeted therapeutic approaches. In this study, we identified String (Stg)/Cdc25 phosphatase as a suppressor of abnormal Tau phosphorylation and associated toxicity. Using a Drosophila model of tauopathy, we showed that Tau dephosphorylation by Stg/Cdc25 correlates with reduced Tau oligomerization, brain vacuolization and locomotor deficits in flies. Moreover, using a disease mimetic model, we provided evidence that Stg/Cdc25 reduces Tau phosphorylation levels independently of Tau aggregation status and delays neurodegeneration progression in the fly. These findings uncover a role for Stg/Cdc25 phosphatases as regulators of Tau biology that extends beyond their well-characterized function as cell-cycle regulators during cell proliferation, and indicate Stg/Cdc25-based approaches as promising entry points to target abnormal Tau phosphorylation.

Integrating animal development: How hormones and metabolism regulate developmental transitions and brain formation.

Our current knowledge on how individual tissues or organs are formed during animal development is considerable. However, the development of each organ does not occur in isolation and thus their formation needs to be done in a coordinated manner. This coordination is regulated by hormones, systemic signals that instruct the simultaneous development of all organs and direct tissue specific developmental programs. In addition, multi- and individual-organ development requires the integration of the nutritional state of the animal, since this affects nutrient availability necessary for the progression of development and growth. Variations in the nutritional state of the animal are normal during development, as the sources and access to nutrients greatly differ depending on the animal stage. Furthermore, adversities of the external environment also exert major alterations in extrinsic nutritional conditions. Thus, both in normal and malnutrition circumstances, the animal needs to trigger metabolic changes to maintain energy homeostasis and sustain growth and development. This metabolic flexibility is mediated by hormones, that drive both developmental encoded metabolic transitions throughout development and adaptation responses according to the nutritional state of the animal. This review aims to provide a comprehensive summary of the current knowledge of how endocrine regulation coordinates multi-organ development by orchestrating metabolic transitions and how it integrates metabolic adaptation responses to starvation. We also focus on the particular case of brain development, as it is extremely sensitive to hormonally induced metabolic changes. Finally, we discuss how brain development is prioritized over the development of other organs, as its growth can be spared from nutrient deprivation.

Six-minute walk test in healthy children: is the leg length important?

RATIONALE: Measures as height, age, and weight influence the six-minute walk test (6MWT). It was shown that children's true leg length (TLL) influence the 6MWT distance but so far it has never been evaluated how much this variable could predict the distance walked related to height. Our hypothesis is that there should not have any significant difference between models including height or TLL. OBJECTIVE: To establish and to compare the predicted walked distance of healthy children in the 6MWT by two distinct models, one including TLL and other including height. METHODS: Observational cross sectional study. A total of 161 healthy children (84 girls, 52.2%), 6-13 years old from three local primary and secondary schools. Two 6MWT were performed following ATS guidelines. Weight, height, and TLL were measured. The longer walked distance was selected for statistical analysis. RESULTS: Anthropometric data were similar for both genders into each group of age. Mean (±SD) walked distances in whole group were: boys 704.4 m (77.7); girls 681.6 m (67.9; P = 0.049). In the univariate regression to predict the distance walked, the adjusted coefficients to TLL and height were in boys: 0.46 and 0.39; and in girls: 0.35 and 0.29, respectively. After adjusting for age and weight, the residuals of the two equations were not significantly different (P = 0.998). CONCLUSION: The model including TLL to predict the walked distance by healthy children explained more of the variation on the walked distance in the 6MWT than the model using the height but without significant difference between the models.

Estereótipos e essencialização de brancos e negros: um estudo comparativo / Stereotypes and the essencialization of black and white people: a comparative study

O combate aos efeitos negativos dos estereótipos, dos preconceitos e da exclusão social é um problema recorrente da nossa época. Um dos maiores desafios enfrentados por quem se dedica a refletir acerca deste tema se refere ao papel desempenhado pelo raciocínio categórico essencialista. O objetivo principal do presente artigo é apresentar os resultados de um estudo sobre a essencialização da categoria social raça. O estudo contou com 101 participantes brasileiros e 138 espanhóis. Foi constatado um claro efeito do país no grau de essencialização, assim como foram obtidas evidências de que a essencialização sofreu o impacto da hegemonia da categoria. A análise das explicações adotadas pelos participantes permitiu concluir que, dentre as teorias implícitas, as causas internas foram adotadas com maior frequência, a história causal foi predominantemente utilizada para explicar as mudanças no comportamento e as pressões situacionais foram arroladas para explicar, preferencialmente, a estabilidade da conduta.

Nowadays, one of the main problems of our societies is to fight against the negative effects of stereotypes, prejudices and social exclusion. One of the greatest challenges faced by anyone doing research on this topic is related to the role played by the categorical essentialist thinking. The main objective of this paper is to present the results of the essentialization of race as a social category. 101 Brazilians and 138 Spaniards took part in this study. The results obtained showed a clear effect of the country and the hegemony of the category on the level of essentialization. The analysis of the explanations used by the participants allows us to conclude that within common sense theories, internal causes were the ones most frequently pointed out, causal history was predominantly adopted to explain changes in behavior and, finally, situational pressures were presented to explain, preferably, stability in behavior.

Estereótipos e essencialização de brancos e negros: um estudo comparativo / Stereotypes and the essencialization of black and white people: a comparative study

O combate aos efeitos negativos dos estereótipos, dos preconceitos e da exclusão social é um problema recorrente da nossa época. Um dos maiores desafios enfrentados por quem se dedica a refletir acerca deste tema se refere ao papel desempenhado pelo raciocínio categórico essencialista. O objetivo principal do presente artigo é apresentar os resultados de um estudo sobre a essencialização da categoria social raça. O estudo contou com 101 participantes brasileiros e 138 espanhóis. Foi constatado um claro efeito do país no grau de essencialização, assim como foram obtidas evidências de que a essencialização sofreu o impacto da hegemonia da categoria. A análise das explicações adotadas pelos participantes permitiu concluir que, dentre as teorias implícitas, as causas internas foram adotadas com maior frequência, a história causal foi predominantemente utilizada para explicar as mudanças no comportamento e as pressões situacionais foram arroladas para explicar, preferencialmente, a estabilidade da conduta.(AU)

Nowadays, one of the main problems of our societies is to fight against the negative effects of stereotypes, prejudices and social exclusion. One of the greatest challenges faced by anyone doing research on this topic is related to the role played by the categorical essentialist thinking. The main objective of this paper is to present the results of the essentialization of race as a social category. 101 Brazilians and 138 Spaniards took part in this study. The results obtained showed a clear effect of the country and the hegemony of the category on the level of essentialization. The analysis of the explanations used by the participants allows us to conclude that within common sense theories, internal causes were the ones most frequently pointed out, causal history was predominantly adopted to explain changes in behavior and, finally, situational pressures were presented to explain, preferably, stability in behavior.(AU)