Development of methods for monitoring organic objects using arsenated sorbents

The paper considers the use of arsenic organic compounds as selective sorbents for the separation and analysis of complex organic mixtures. Based on the chromatographic factors of polarity, it was found that the studied sorbents range is characterized by high hydroxyl selectivity of the analyzed sorbates separation, due to the arsenyl oxygen presence in the structure of their molecule, which has an unshielded electron pair. It is shown that the functional substituents in the structure of the arsenic sorbents molecule have a direct effect on the chromatographic factors of polarity, the values of which increase when the functional substituents in the the phenyl ring (para-position) are introduced into the structure of the molecule. It was found that relatively low values of the chromatographic polarity factor (x) are observed for benzene, which also increases in the para-position of the ring. Based on the five-dimensional space and projection on the plane corresponding to the chromatographic factors of polarity, arsenic sorbents with extreme characteristics that have higher chromatographic factors of polarity (y) in comparison with known analogues were identified. Based on the conducted research, it was found that arsenic sorbents show high separation selectivity of aliphatic alcohols from hydrocarbons. Thus, when developing specific methods for the analysis of complex alcohol-hydrocarbon mixtures, we propose to use arsenic compounds as selective sorbents intended for the separation and analysis of substances capable of forming intermolecular hydrogen bonds under gas-liquid chromatography. At the same time, their retention times are higher than similar characteristics of non-polar compounds. This allows you to separate the analyzed components with close retention times.

Activation of polarized cell growth by inhibition of cell polarity

A key feature of cells is the capacity to activate new functional polarized domains contemporaneously to pre-existing ones. How cells accomplish this is not clear. Here, we show that in fission yeast inhibition of cell polarity at pre-existing domains of polarized cell growth is required to activate new growth. This inhibition is mediated by the ERM-related polarity factor Tea3, which antagonizes the activation of the Rho-GTPase Cdc42 by its co-factor Scd2. We demonstrate that Tea3 acts in a phosphorylation-dependent manner controlled by the PAK kinase Shk1 and that, like Scd2, Tea3 is direct substrate of Shk1. Importantly, we show that Tea3 and Scd2 compete for their binding to Shk1, indicating that their biochemical competition for Shk1 underpins their antagonistic roles in controlling polarity. Thus, by preventing pre-existing growth domains from becoming overpowering, Tea3 allows cells to redistribute their polarity-activating machinery to prospective sites and control their timing of activation.

Meru couples planar cell polarity with apical-basal polarity during asymmetric cell division

Polarity is a shared feature of most cells. In epithelia, apical-basal polarity often coexists, and sometimes intersects with planar cell polarity (PCP), which orients cells in the epithelial plane. From a limited set of core building blocks (e.g. the Par complexes for apical-basal polarity and the Frizzled/Dishevelled complex for PCP), a diverse array of polarized cells and tissues are generated. This suggests the existence of little-studied tissue-specific factors that rewire the core polarity modules to the appropriate conformation. In Drosophila sensory organ precursors (SOPs), the core PCP components initiate the planar polarization of apical-basal determinants, ensuring asymmetric division into daughter cells of different fates. We show that Meru, a RASSF9/RASSF10 homologue, is expressed specifically in SOPs, recruited to the posterior cortex by Frizzled/Dishevelled, and in turn polarizes the apical-basal polarity factor Bazooka (Par3). Thus, Meru belongs to a class of proteins that act cell/tissue-specifically to remodel the core polarity machinery.

Reconstructing regulatory pathways by systematically mapping protein localization interdependency networks

ABSTRACTA key goal of functional genomics is to elucidate how genes and proteins act together in space and time, wired as pathways, to control specific aspects of cell biological function. Here, we develop a method to quantitatively determine proteins’ localization interdependencies at high throughput. We show that this method can be used to systematically obtain weighted, signed and directional pathway relationships, and hence to reconstruct a detailed pathway wiring. As proof-of-principle, we focus on 42 factors that control cell polarity in fission yeast (Schizosaccharomyces pombe) and use high-throughput confocal microscopy and quantitative image analysis to reconstruct their Localization Interdependency Network (LIN). Through this approach we identify 554 pairwise interactions across the factors, including 98% putative new directed links. Validation of an unexpected interaction between two polarity factor subgroups - the polarity landmark proteins and the cell integrity pathway components - by orthogonal phenotyping demonstrates the power of the LIN approach in detecting subtle, systems-level causal connections.