Molybdenum (Mo) is an essential trace element in all kingdoms of life. Mo is bioavailable as the oxyanion molybdate and gains biological activity in eukaryotes when bound to molybdopterin, forming the molybdenum cofactor. The imbalance of molybdate homeostasis results in growth deficiencies or toxic symptoms within plants, fungi and animals. Recently, fluorescence resonance energy transfer (FRET) methods have emerged, monitoring cellular and subcellular molybdate distribution dynamics using a genetically encoded molybdate-specific FRET nanosensor, named MolyProbe. Here, we show that the MolyProbe system is a fast and reliable in vitro assay for quantitative molybdate determination. We added a Strep-TagII affinity tag to the MolyProbe protein for quick and easy purification. This MolyProbe is highly stable, resistant to freezing and can be stored for several weeks at 4 °C. Furthermore, the molybdate sensitivity of the assay peaked at low nM levels. Additionally, The MolyProbe was applied in vitro for quantitative molybdate determination in cell extracts of the plant Arabidopsis thaliana, the fungus Neurospora crassa and the yeast Saccharomyces cerevisiae. Our results show the functionality of the Arabidopsis thaliana molybdate transporter MOT1.1 and indicate that FRET-based molybdate detection is an excellent tool for measuring bioavailable Mo.

The eukaryotic actin cytoskeleton comprises the protein itself in its monomeric and filamentous forms, G- and F-actin, as well as multiple interaction partners (actin-binding proteins, ABPs). This gives rise to a temporally and spatially controlled, dynamic network, eliciting a plethora of motility-associated processes. To interfere with the complex inter- and intracellular interactions the actin cytoskeleton confers, small molecular inhibitors have been used, foremost of all to study the relevance of actin filaments and their turnover for various cellular processes. The most prominent inhibitors act by, e.g., sequestering monomers or by interfering with the polymerization of new filaments and the elongation of existing filaments. Among these inhibitors used as tool compounds are the cytochalasans, fungal secondary metabolites known for decades and exploited for their F-actin polymerization inhibitory capabilities. In spite of their application as tool compounds for decades, comprehensive data are lacking that explain (i) how the structural deviances of the more than 400 cytochalasans described to date influence their bioactivity mechanistically and (ii) how the intricate network of ABPs reacts (or adapts) to cytochalasan binding. This review thus aims to summarize the information available concerning the structural features of cytochalasans and their influence on the described activities on cell morphology and actin cytoskeleton organization in eukaryotic cells.

The most established numerical methods for calculation of sound radiation are the boundary-element-method (BEM) and the finite-element-method (FEM). For large-scale geometries and high-frequency ranges these methods are limited by enormous numerical costs. The applicability of the energy-finite-element-method (EFEM) in these cases is analyzed within the research project EPES, sponsored by the Federal Ministry of Economy and Technology. Under certain assumptions, the equations describing structure-borne sound and sound radiation can be condensed to the static heat conduction equation, transforming the pressure and velocities in energy densities. Using EFEM, the structure geometry and acoustic cavities are separately modeled and coupled by transmission coefficients for energy flow interactions. An important value calculating the coefficients is the radiation efficiency. This paper focuses on the analysis of the radiation efficiency for EFEM calculations. This contribution presents the EFEM approach, calculations of radiation efficiency, transmission coefficients and energy densities of different fluid-structure interactions. Based on those calculations, the applicability of the EFEM is discussed.

The most established numerical methods for calculation of sound radiation are the Boundary-Element-Method (BEM) and the FiniteElementMethod (FEM). For large-scale geometries and high-frequency ranges these methods are limited by enormous numerical costs. The applicability of the Energy-Finite-Element-Method (EFEM) in these cases is analyzed within the research project EPES, sponsored by the federal ministry of economy and technology. Under certain assumptions the equations describing structure-borne sound and sound radiation can be condensed to the static heat conduction equation, transforming the pressure and velocities in energy densities. Using the Energy-FiniteElement-Method (EFEM) the structure geometry and acoustic cavities are separately modeled and coupled by transmission coefficients for energy flow interactions. An important value calculating the coefficients is the radiation efficiency. This paper focuses on the analysis of the radiation efficiency for EFEM calculations. This contribution presents the EFEM approach, calculations of radiation efficiency, transmission coefficients and energy densities of different fluid-structure interactions. Based on those calculations, the applicability of the EFEM is discussed.