Three-phase Contact Expansion During the Bubble Adhesion on an Inclined Plane

AbstractThe bubble attachment onto a collecting surface is a common natural phenomenon and the bubble-particle interactions are used in numerous industrial applications. The adhesion process between a small single rising bubble and a stationary solid particle with hydrophobic surface in stagnant liquid is studied in this project. The real particle is replaced by a prism with an inclined plane representing a spherical particle with infinite diameter. Experiments were performed using a freely rising bubble method. The influence of bubble size and type of bubble surface mobility was studied and described both experimentally and theoretically. The molecular-kinetic and hydrodynamic models were used for theoretical description of the TPC expansion. According to our results, hydrodynamic model is not appropriate for the TPC line calculation. The value of its adjustable parameter is not in accordance with physical assumption. The molecular-kinetic model gives better results. Two adjustable parameters (the frequency of the molecular displacement and the average jumping distance) were calculated and their values correspond to the physical assumptions. It was found that the bubble size is the most important parameter influencing the TPC line expansion. The influence of bubble surface mobility is surprisingly low. Only the frequency of the molecular displacement differs for bubbles with mobile or immobile surface. This conclusion corresponds to the theoretical assumption that the presence of surface active agents decelerates the bubble motion

Quantitative differential proteomics of yeast extracellular matrix: there is more to it than meets the eye

Background: Saccharomyces cerevisiae multicellular communities are sustained by a scaffolding extracellular matrix, which provides spatial organization, and nutrient and water availability, and ensures group survival. According to this tissue-like biology, the yeast extracellular matrix (yECM) is analogous to the higher Eukaryotes counterpart for its polysaccharide and proteinaceous nature. Few works focused on yeast biofilms, identifying the flocculin Flo11 and several members of the HSP70 in the extracellular space. Molecular composition of the yECM, is therefore mostly unknown. The homologue of yeast Gup1 protein in high Eukaryotes (HHATL) acts as a regulator of Hedgehog signal secretion, therefore interfering in morphogenesis and cell-cell communication through the ECM, which mediates but is also regulated by this signalling pathway. In yeast, the deletion of GUP1 was associated with a vast number of diverse phenotypes including the cellular differentiation that accompanies biofilm formation. Methods: S. cerevisiae W303-1A wt strain and gup1Δ mutant were used as previously described to generate biofilmlike mats in YPDa from which the yECM proteome was extracted. The proteome from extracellular medium from batch liquid growing cultures was used as control for yECM-only secreted proteins. Proteins were separated by SDS-PAGE and 2DE. Identification was performed by HPLC, LC-MS/MS and MALDI-TOF/TOF. The protein expression comparison between the two strains was done by DIGE, and analysed by DeCyder Extended Data Analysis that included Principal Component Analysis and Hierarchical Cluster Analysis. Results: The proteome of S. cerevisiae yECM from biofilm-like mats was purified and analysed by Nano LC-MS/MS, 2D Difference Gel Electrophoresis (DIGE), and MALDI-TOF/TOF. Two strains were compared, wild type and the mutant defective in GUP1. As controls for the identification of the yECM-only proteins, the proteome from liquid batch cultures was also identified. Proteins were grouped into distinct functional classes, mostly Metabolism, Protein Fate/Remodelling and Cell Rescue and Defence mechanisms, standing out the presence of heat shock chaperones, metalloproteinases, broad signalling cross-talkers and other putative signalling proteins. The data has been deposited to the ProteomeXchange with identifier PXD001133.Conclusions: yECM, as the mammalian counterpart, emerges as highly proteinaceous. As in higher Eukaryotes ECM, numerous proteins that could allow dynamic remodelling, and signalling events to occur in/and via yECM were identified. Importantly, large sets of enzymes encompassing full antagonistic metabolic pathways, suggest that mats develop into two metabolically distinct populations, suggesting that either extensive moonlighting or actual metabolism occurs extracellularly. The gup1Δ showed abnormally loose ECM texture. Accordingly, the correspondent differences in proteome unveiled acetic and citric acid producing enzymes as putative players in structural integrity maintenance.This work was funded by the Marie Curie Initial Training Network GLYCOPHARM (PITN-GA-2012-317297), and by national funds from FCT I.P. through the strategic funding UID/BIA/04050/2013. Fábio Faria-Oliveira was supported by a PhD scholarship (SFRH/BD/45368/2008) from FCT (Fundação para a Ciência e a Tecnologia). We thank David Caceres and Montserrat MartinezGomariz from the Unidad de Proteómica, Universidad Complutense de Madrid – Parque Científico de Madrid, Spain for excellent technical assistance in the successful implementation of all proteomics procedures including peptide identification, and Joana Tulha from the CBMA, Universidade do Minho, Portugal, for helping with the SDS-PAGE experiments, and the tedious and laborious ECM extraction procedures. The mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium, via the PRIDE partner repository, with the dataset identifier PXD001133. We would like to thank the PRIDE team for all the help and support during the submission process.info:eu-repo/semantics/publishedVersio

Methodologies to generate, extract, purify and fractionate yeast ECM for analytical use in proteomics and glycomics

In a multicellular organism, the extracellular matrix (ECM) provides a cell-supporting scaffold and helps maintaining the biophysical integrity of tissues and organs. At the same time it plays crucial roles in cellular communication and signalling, with implications in spatial organisation, motility and differentiation. Similarly, the presence of an ECM-like extracellular polymeric substance is known to support and protect bacterial and fungal multicellular aggregates, such as biofilms or colonies. However, the roles and composition of this microbial ECM are still poorly understood.Authors would like to acknowledge Joana Tulha for assistance on yeasts overlay photographs, and to Rui Armada for C. albicans ECM SDS-PAGE experiment. The proteomic analysis was carried out at the proteomics facility UCM-PCM, a member of the ProteoRed network. The polysaccharide analysis was performed at the Laboratory of Glycoconjugates Biochemistry and Cellular Biology, UFRJ, Brazil. Fabio Faria-Oliveira was supported by a PhD scholarship SFRH/BD/45368/2008 from FCT (Fundacao para a Ciencia e a Tecnologia). This work was funded by Marie Curie Initial Training Network GLYCOPHARM (PITN-GA-2012-317297), and by FCT/MEC through Portuguese funds (PIDDAC) - PEst-OE/BIA/UI4050/2014. The authors would also like to acknowledge Hugh S. Johnson for critical reading of the manuscript regarding English usage