Extração seletiva da fração húmica característica das terras pretas de índios.

As Terras Pretas de Índios (TPI), encontradas na Amazônia, são solos extremamente férteis e ricos em carbono, e essa fertilidade se mantém no tempo a despeito do seu uso (resiliência). Essas características se devem principalmente às propriedades da matéria orgânica desses solos, de caráter pirogênico. Tendo isso em vista, esses solos nos fornecem um excelente modelo de agricultura sustentável e que seqüestra carbono. Embora o empenho na reprodução das TPI seja grande, não existe um método analítico que possa aferir seu êxito. Estudos utilizando a espectroscopia de Ressonância Magnética Nuclear de 13C e Resolução Multivariada de Curvas (MCR) mostram que os ácidos húmicos (AH) das TPI podem ser satisfatoriamente modelados como uma mistura binária, sendo o espectro estimado de um dos componentes similar àquele de AH obtidos de solos tropicais ordinários. Por outro lado, o outro componente é caracterizado por estruturas aromáticas policondensadas e funcionalizadas com grupos carboxílicos ligados diretamente aos C aromáticos, sendo essa a responsável pela principal diferença encontrada entre as TPI e os solos adjacente, explicando sua elevada fertilidade e sustentabilidade. Os espectros dos AH das TPI obtidos a partir da extração com soluções aquosas de NaOH ajustadas a pH 7 e 10,6 apresentaram uma grande similaridade com aquele obtido com MCR para o componente rico em estruturas policondensadas e funcionalizadas, o que vem não somente confirmar a precisão e exatidão do modelo matemático, como também sugerir a utilização dessa extração como um método rápido para aferição das propostas de se reproduzir esses solos especiais

Bioactive CMC-Based films enriched with green coffee oil and itsresidues.

SIAN. 17 e 18 de junho de 2019. Oral. R002

Fyn Mediates Leptin Actions in the Thymus of Rodents

BACKGROUND:Several effects of leptin in the immune system rely on its capacity to modulate cytokine expression and apoptosis in the thymus. Surprisingly, some of these effects are dependent on signal transduction through the IRS1/PI3-kinase, but not on the activation of JAK2. Since all the well known effects of leptin in different cell types and tissues seem to be dependent on JAK2 activation, we hypothesized that, at least for the control of thymic function, another, unknown kinase could mediate the transduction of the leptin signal from the ObR towards the IRS1/PI3-kinase signaling cascade. METHODOLOGY/PRINCIPAL FINDINGS:Here, by employing immunoblot, real-time PCR and flow citometry we show that the tyrosine kinase, Fyn, is constitutively associated with the ObR in thymic cells. Following a leptin stimulus, Fyn undergoes an activating tyrosine phosphorylation and a transient association with IRS1. All these effects are independent of JAK2 activation and, upon Fyn inhibition, the signal transduction towards IRS1/PI3-kinase is abolished. In addition, the inhibition of Fyn significantly modifies the effects of leptin on thymic cytokine expression. CONCLUSION/SIGNIFICANCE:Therefore, in the thymus, Fyn acts as a tyrosine kinase that transduces the leptin signal independently of JAK2 activation, and mediates some of the immunomodulatory effects of leptin in this tissue

High-Fat Diet Induces Apoptosis of Hypothalamic Neurons

Consumption of dietary fats is amongst the most important environmental factors leading to obesity. In rodents, the consumption of fat-rich diets blunts leptin and insulin anorexigenic signaling in the hypothalamus by a mechanism dependent on the in situ activation of inflammation. Since inflammatory signal transduction can lead to the activation of apoptotic signaling pathways, we evaluated the effect of high-fat feeding on the induction of apoptosis of hypothalamic cells. Here, we show that consumption of dietary fats induce apoptosis of neurons and a reduction of synaptic inputs in the arcuate nucleus and lateral hypothalamus. This effect is dependent upon diet composition, and not on caloric intake, since pair-feeding is not sufficient to reduce the expression of apoptotic markers. The presence of an intact TLR4 receptor, protects cells from further apoptotic signals. In diet-induced inflammation of the hypothalamus, TLR4 exerts a dual function, on one side activating pro-inflammatory pathways that play a central role in the development of resistance to leptin and insulin, and on the other side restraining further damage by controlling the apoptotic activity