Electron Probe Micro-Analysis and Laser Microprobe Mass Analysis of Material Leached from a Limestone Cathedral

Electron probe X-ray micro-analysis (EPXMA) and Laser microprobe mass analysis (LAMMA), were applied to characterize the leachate of sandy limestones of a Belgian cathedral. Individual suspended particles, found in water that was sprayed over the cathedral walls ( 1 each ate water ), were sized and analyzed by automated EPXMA-analysis, and classified with hierarchical cluster methods. LAMMA was used to gather more information about particles, present in the solution, as well as in suspension. It was found that the leachate from black walls, had a high sulphate concentration and a large variety of particles in suspension, with different morphology and composition, with silicates as most abundant group. The leachate from white walls is characterized by a predominant Ca-rich suspension, with both original and recrystallized calcite particles, and by a much lower sulphate-ion concentration in the solution. LAMMA-analysis revealed that the organic group of the EPXMA-analysis, consists mostly of carbon-containing fly-ash particles. Hence, in general, it could be concluded that walls which are not subject to direct rainfall are generally covered with a gypsum crust, that turns black due to adhesion of soil dust and fly-ash particles, while white walls become thinner due to rainwater erosion of weathering products and original stone components

Molecular basis and dual ligand regulation of tetrameric Estrogen Receptor α/14-3-3ζ protein complex

Therapeutic strategies targeting Nuclear Receptors (NRs) beyond their endogenous ligand binding pocket have gained significant scientific interest, driven by a need to circumvent problems associated with drug resistance and pharmacological profile. The hub protein 14-3-3 is an endogenous regulator of various NRs, providing a novel entry point for small molecule modulation of NR activity. Exemplified, 14-3-3 binding to the C-terminal F-domain of the Estrogen Receptor alpha (ERα), and small molecule stabilization of the ERα/14-3-3ζ protein complex by the natural product Fusicoccin A (FC-A), was demonstrated to downregulate ERα-mediated breast cancer proliferation. This presents a novel drug discovery approach to target ERα, however, structural and mechanistic insights into ERα/14-3-3 complex formation are lacking. Here, we provide an in-depth molecular understanding of the ERα/14-3-3ζ complex by isolating 14-3-3ζ in complex with an ERα protein construct comprising its Ligand Binding Domain (LBD) and phosphorylated F-domain. Bacterial co-expression and co-purification of the ERα/14-3-3ζ complex, followed by extensive biophysical and structural characterization, revealed a tetrameric complex between the ERα homodimer and the 14-3-3ζ homodimer. 14-3-3ζ binding to ERα, and ERα/14-3-3ζ complex stabilization by FC-A, appeared to be orthogonal to ERα endogenous agonist (E2) binding, E2-induced conformational changes, and cofactor recruitment. Similarly, the ERα antagonist 4-hydroxytamoxifen inhibited cofactor recruitment to the ERα LBD while ERα was bound to 14-3-3ζ. Furthermore, stabilization of the ERα/14-3-3ζ protein complex by FC-A was not influenced by the disease-associated and 4-hydroxytamoxifen resistant ERα-Y537S mutant. Together, these molecular and mechanistic insights provide direction for targeting ERα via the ERα/14-3-3 complex as an alternative drug discovery approach.</p

Micro-CT-scanning as a valuable source of data for musculoskeletal studies in biology

Over time, so-called classic biological studies (such as anatomical studies) have evolved into modern, highly integrated strategies tackling important questions in evolutionary biology. Where early morphologists limited themselves to descriptions based on dissections, non-invasive imaging techniques nowadays allow to uncover details of anatomy in a way that morphologists can go far beyond basic and descriptive anatomy, e.g. through modelling. In this presentation, an overview is presented on some on-going research projects that rely on X-ray tomography data, which focus on the adaptive evolution of musculoskeletal systems in different vertebrate lineages. Cases discussed are (1) a study on the cranial anatomical diversity and functional implications in the feeding apparatus in seahorses, (2) as well as multi-body modelling of the tail system in these fishes; and (3) structural diversity in Darwin’s finches in relation to high performance seed cracking. These cases clearly show the (still not fully explored) potential for testing specific hypotheses with respect to adaptive evolution, where X-ray tomography provides the tools to model experimental conditions that are impossible to achieve with live specimens (e.g. perfect control of specific parameters)

Organophosphate Insecticides Target the Serotonergic System in Developing Rat Brain Regions: Disparate Effects of Diazinon and Parathion at Doses Spanning the Threshold for Cholinesterase Inhibition

BACKGROUND: In the developing brain, serotonin (5HT) systems are among the most sensitive to disruption by organophosphates. OBJECTIVES: We exposed neonatal rats to daily doses of diazinon or parathion on postnatal days (PND)1–4 and evaluated 5HT receptors and the 5HT transporter in brainstem and forebrain on PND5, focusing on doses of each agent below the maximum tolerated dose and spanning the threshold for cholinesterase inhibition: 0.5, 1, or 2 mg/kg for diazinon, and 0.02, 0.05, and 0.1 mg/kg for parathion. RESULTS: Diazinon evoked up-regulation of 5HT(1A) and 5HT(2) receptor expression even at doses devoid of effects on cholinesterase activity, a pattern similar to that seen earlier for another organophosphate, chlorpyrifos. In contrast, parathion decreased 5HT(1A) receptors, again at doses below those required for effects on cholinesterase. The two agents also differed in their effects on the 5HT transporter. Diazinon evoked a decrease in the brainstem and an increase in the forebrain, again similar to that seen for chlorpyrifos; this pattern is typical of damage of nerve terminals and reactive sprouting. Parathion had smaller, nonsignificant effects. CONCLUSIONS: Our results buttress the idea that, in the developing brain, the various organophosphates target specific neurotransmitter systems differently from each other and without the requirement for cholinesterase inhibition, their supposed common mechanism of action