Navegando por Palavras-chave "Condensation"

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    A biophysical study of DNA condensation mediated by histones and protamines
    (Elsivier, 2022-12-15) da Silva, Emerson Rodrigo [UNIFESP]; Souza, Bruna B.S. [UNIFESP]; Lourenço, Thiago C. [UNIFESP]; Gerbelli, Barbara B.; Oseliero Filho, Pedro L.; Oliveira, Cristiano L.P. [UNIFESP]; Miranda, Antonio [UNIFESP]; http://lattes.cnpq.br/7800589206457326
    The compaction of long DNA strands into confined spaces such as the nuclei of eukaryotic cells is an essential phenomenon towards the emergence of elaborated forms of life. Histones and protamines are the major nucleoproteins involved in this task participating in the formation of chromatin in somatic and germinative cells, respectively. In addition to a fundamental understanding of critical biological processes, DNA condensation also holds strong potential in biotechnology. Herein, we investigate the mesoscale structure of complexes formed between DNA and histones or protamines. A sophisticated set of biophysical methods encompassing steady-state fluorimetry, small-angle X-ray scattering and infrared nano spectroscopy was used to unveil both the self-assembly and molecular interactions of these complexes. We explored the fluorescence of a molecular rotor, thioflavin T, to investigate the accessibility of ligands in the inter-base environment of DNA strands. AFM-based infrared spectroscopy was used for the first time to probe the vibrational signature of individual DNA/nucleoprotein nano assemblies and disclose secondary-structure features. Our results show that protamines form highly compact structures in which DNA folding hinders access to the inter-base spacing. These assemblies exhibit diversified secondary-structure conformations, with the presence of -sheets stabilizing the packing. In contrast, histone-based complexes are characterized by fibrillar nano assemblies exhibiting larger inter strands separations and access to guest molecules that intercalate between bases. The findings presented here may help the understanding of DNA condensation mediated by these two major nucleoproteins and may assist the optimization of gene vehicles based on these promising nano assemblies.
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    Effects of the stimulus phase on the air-conducted ocular vestibular evoked myogenic potential in healthy subjects
    (Elsevier Ireland Ltd, 2017) Amorim, Fernanda Emanuelle Almeida Castro [UNIFESP]; Sahdo, Alinne Martiniano [UNIFESP]; Giuliano, Lydia Maria Pereira [UNIFESP]; Pinheiro, Denise Spinola [UNIFESP]; Braga, Nadia Iandoli de Oliveira [UNIFESP]; Manzano, Gilberto Mastrocola [UNIFESP]
    Objective: The study aimed to examine the effect of the stimulus phase of air-conducted sound on ocular vestibular evoked myogenic potentials (oVEMPs). Methods: oVEMPs were recorded after air-conducted sounds (500 Hz, 4 ms duration), presented with initial condensation (positive), rarefaction (negative), and alternant polarities from 12 healthy subjects. Results: Most responses showed a bifid n10 peak separated by similar to 1.9 ms. The most prominent sub-peak after condensation was shorter than the most prominent sub-peak after rarefaction