The limited access to functional human brain tissue has led to the development of stem cell-based alternative models. The differentiation of human pluripotent stem cells into cerebral organoids with self-organized architecture has created novel opportunities to study the early stages of the human cerebral formation. Here we applied state-of-the-art label-free shotgun proteomics to compare the proteome of stem cell-derived cerebral organoids to the human fetal brain. We identified 3,073 proteins associated with different developmental stages, from neural progenitors to neurons, astrocytes, or oligodendrocytes. The major protein groups are associated with neurogenesis, axon guidance, synaptogenesis, and cortical brain development. Glial cell proteins related to cell growth and maintenance, energy metabolism, cell communication, and signaling were also described. Our data support the variety of cells and neural network functional pathways observed within cell-derived cerebral organoids, confirming their usefulness as an alternative model. The characterization of brain organoid proteome is key to explore, in a dish, atypical and disrupted processes during brain development or neurodevelopmental, neurodegenerative, and neuropsychiatric diseases.
Docosahexaenoic acid (DHA) is an n-3 polyunsaturated fatty acid that is highly enriched in the brain, and the oxidation products of DHA are present or increased during neurodegenerative disease progression. The characterization of the oxidation products of DHA is critical to understanding the roles that these products play in the development of such diseases. In this study, we developed a sensitive and specific analytical tool for the detection and quantification of twelve major DHA hydroperoxide (HpDoHE) and hydroxide (HDoHE) isomers (isomers at positions 4, 5, 7, 8, 10, 11, 13, 14, 16, 17, 19 and 20) in biological systems. In this study, HpDoHE were synthesized by photooxidation, and the corresponding hydroxides were obtained by reduction with NaBH4. The isolated isomers were characterized by LC-MS/MS, and unique and specific fragment ions were chosen to construct a selected reaction monitoring (SRM) method for the targeted quantitative analysis of each HpDoHE and HDoHE isomer. The detection limits for the LC-MS/MS-SRM assay were 1−670 pg for HpDoHE and 0.5−8.5 pg for HDoHE injected onto a column. Using this method, it was possible to detect the basal levels of HDoHE isomers in both rat plasma and brain samples. Therefore, the developed LC-MS/MS-SRM can be used as an important tool to identify and quantify the hydro(pero)xy derivatives of DHA in biological system and may be helpful for the oxidative lipidomic studies.
Recebido em 24/8/11; aceito em 29/8/11; publicado na web em 30/9/11 MASS SPECTROMETRY NOMENCLATURE IN PORTUGUESE LANGUAGE. In commemoration of the International Year of Chemistry this article presents the normalization and standardization of key terms used in mass spectrometry in Portuguese Language.Keywords: mass spectrometry; nomenclature; Portuguese language. INTRODUÇÃOO Ano Internacional da Química (AIQ), em 2011, tem sido celebrado através de diferentes ações. Os colegas, durante este ano, já perceberam o resultado dessa iniciativa tomada na 63 a Sessão da Assembleia Geral da ONU, que visa celebrar a contribuição da Química para a humanidade, com o lema Chemistry -our life, our future. Além da esperada reflexão sobre o estado da arte na Química, as sociedades científicas estão atuando na organização de eventos de grande porte com fóruns internacionais, em ações de divulgação como feiras de ciências e mídia, em ações educativas como confecção de materiais didáticos para o ensino médio, entre outras. Nesse contexto, o Presidente da Sociedade Internacional de Espectrometria de Massas, um dos organizadores do compêndio de nomenclatura na área junto à IUPAC, indicou a membros da Sociedade Brasileira de Espectrometria de Massas e da Sociedade Brasileira de Química que organizassem um material didático sobre o tema em língua portuguesa. O material compilado faz uma adaptação para nossa língua dos termos e definições usados de forma corrente em espectrometria de massas. Para isso, sugerimos a leitura das referências que se encontram no final desse texto, 1-11 onde estão as definições em língua inglesa, com os créditos aos autores pioneiros, que compilaram as terminologias originais. Esperamos que esse material educativo auxilie o grande número de pesquisadores, professores e estudantes que atuam na área e que, assim, possamos ter uma comunicação em espectrometria de massas mais eficiente em nosso idioma. TERMOS EM ORDEM ALFABÉTICAAblação por laser -laser ablation Remoção de material de uma amostra sólida ou líquida, através de energia fornecida por um laser de pulso curto para formar espécies em fase gasosa e partículas.Abundância isotópica natural -natural isotopic abundance A abundância isotópica de um elemento da maneira como encontrado na natureza. Afinidade eletrônica (AE) -electron affinity (EA)Energia mínima necessária para a formação de uma espécie neutra a partir de um ânion radical pelo processo M - Agregado iônico -ion clusterUm íon formado pela combinação, por interações não covalentes, de dois ou mais átomos ou moléculas de uma ou mais espécies quí-
Atmospheric solids analysis probe mass spectrometry (ASAP-MS) is a powerful tool for analysis of solid and liquid samples. It is an excellent alternative for crude oil analysis without any sample preparation step. Here, ASAP-MS in positive ion mode, ASAP(+)-MS, has been optimized for analysis of condensed aromatics (CA) standards, crude oil, and paraffinic fraction samples using a Synapt G2-S HDMS. Initially, two methodologies were used to access the chemical composition of samples: (1) using a temperature gradient varying from 150 to 600 °C at a heating rate of 150 °C min, and (2) with constant temperature of 300 and 400 °C. ASAP(+)-MS ionized many compounds with a typical petroleum profile, showing a greater signals range of m/z 250-1300 and 200-1400 for crude oil and paraffin samples, respectively. Such performance, mainly related to the detection of high molecular weight compounds (>1000 Da), is superior to that of other traditional ionization sources, such as ESI, APCI, DART, and DESI. Additionally, the CA standards were identified in both forms: radicals, [M], and protonated cations, [M + H], with minimum fragmentation. Therefore, ASAP was more efficient in accessing the chemical composition of nonpolar and polar compounds. It is promising in its application with ultrahigh resolution MS instruments, such as FT-ICR MS and Orbitrap, since molecular formulas with greater resolution and mass accuracy (<1 ppm) would be assigned. Graphical Abstract ᅟ.
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