Institute of Natural Sciences

The objective of the research is development a mobile application (on the Android platform) designed for visualization of the Solar System with the AR technology and the alphabet study, applying the astronomic definitions, which can be used by the teacher and the students for an effective training for studying the subjects of the astronomic cycle in primary school. Augmented Reality cards with the images of the Solar System planets and other celestial bodies were developed, as well as the “Space alphabet” was created. In the developed alphabet every letter of the alphabet becomes a certain celestial body or a different astronomic definition. Augmented Reality gives the opportunity to visualize images of the Solar System as much as possible, in other words to convert 2D images into 3D, as well as “make them alive”. Applying this tool of ICT while studying new data gives the ability to develop and improve the pupils’ spatial thinking, “to see” the invisible and to understand the perce...

The objective of the research is developing a mobile application (on Android) designed to visualize the basic definitions of the discipline “Radiochemistry and radioecology” in 3D. Studying the education material of this discipline (phenomena of radionuclide, radioisotope, the nucleus, the fundamental particle etc and their specifics) requires a more sophisticated explanation from the teacher and dynamic dimensional image from the student. Decent detailed visualization of the study material makes this process easier. So applying the augmented reality is rational for the purpose of visualizing the study material, applying it allows demonstrate 3D-models of the nucleus, the fundamental particles, the nature of radioactive decay, nuclear fission, the specifics of managing the nuclear weapon and the NPS. Involving this instrument of the up-to-date information and communication technologies while studying the new material gives the opportunity to develop and boost the spatial imagination...

The formation of amyloid fibrils of α-synuclein (αSyn), the key protein in Parkinson's disease, is an autocatalytic process that is seeded by mature αSyn fibrils. Based on systematic measurements of the dependence of the fibril growth rate on the concentrations of monomers and preformed fibrillar seeds, we propose a mechanism of αSyn aggregation that includes monomer binding to fibril ends and secondary nucleation by fibril breaking. The model explains the increase of the αSyn aggregation rate under shaking conditions and the exponential increase in the fraction of fibrillar protein at the initial stages of αSyn aggregation. The proposed autocatalytic mechanism also accounts for the high variability in the aggregation lag time. The rate constant of monomer binding to the ends of fibrils, k + ≈ 1.3 mM −1 s −1 , was estimated from the aggregation rate and previously reported average fibril lengths. From the aggregation rates at low concentrations the binding of monomeric αSyn to fibrils was found to be almost irreversible, with an equilibrium dissociation constant (K d) smaller than 3 μM.

The nucleocapsid protein (NC) plays an important role in HIV-1, mainly through interactions with the genomic RNA and its DNA copies. Though the structures of several complexes of NC with oligonucleotides (ODNs) are known, detailed information on the ODN dynamics in the complexes is missing. To address this, we investigated the steady state and time-resolved fluorescence properties of 2-aminopurine (2Ap), a fluorescent adenine analog introduced at positions 2 and 5 of AACGCC and AATGCC sequences. In the absence of NC, 2Ap fluorescence was strongly quenched in the flexible ODNs, mainly through picosecond to nanosecond dynamic quenching by its neighboring bases. NC strongly restricted the ODN flexibility and 2Ap local mobility, impeding the collisions of 2Ap with its neighbors and thus, reducing its dynamic quenching. Phe 16 !Ala and Trp 37 !Leu mutations largely decreased the ability of NC to affect the local dynamics of 2Ap at positions 2 and 5, respectively, while a fingerless NC was totally ineffective. The restriction of 2Ap local mobility was thus associated with the NC hydrophobic platform at the top of the folded fingers. Since this platform supports the NC chaperone properties, the restriction of the local mobility of the bases is likely a mechanistic component of these properties.

Although the function of biopolymer hydrogels in nature depends on structural anisotropy at mesoscopic length scales, the self-assembly of such anisotropic structures in vitro is challenging. Here we show that fibrils of the protein α-synuclein spontaneously self-assemble into structurally anisotropic hydrogel particles. While the fibrils in the interior of these supra-fibrillar aggregates (SFAs) are randomly oriented, the fibrils in the periphery prefer to cross neighboring fibrils at high angles. This difference in organization coincides with a significant difference in polarity of the environment in the central and peripheral parts of the SFA. We rationalize the structural anisotropy of SFAs in the light of the observation that αS fibrils bind a substantial amount of counterions. We propose that, with the progress of protein polymerization into fibrils, this binding of counterions changes the ionic environment which triggers a change in fibril organization resulting in anisotropy in the architecture of hydrogel particles.

Parkinson disease is characterized cytopathologically by the deposition in the midbrain of aggregates composed primarily of the presynaptic neuronal protein ␣-synuclein (AS). Neurotoxicity is currently attributed to oligomeric microaggregates subjected to oxidative modification and promoting mitochondrial and proteasomal dysfunction. Unphysiological binding to membranes of these and other organelles is presumably involved. In this study, we performed a systematic determination of the influence of charge, phase, curvature, defects, and lipid unsaturation on AS binding to model membranes using a new sensitive solvatochromic fluorescent probe. The interaction of AS with vesicular membranes is fast and reversible. The protein dissociates from neutral membranes upon thermal transition to the liquid disordered phase and transfers to vesicles with higher affinity. The binding of AS to neutral and negatively charged membranes occurs by apparently different mechanisms. Interaction with neutral bilayers requires the presence of membrane defects; binding increases with membrane curvature and rigidity and decreases in the presence of cholesterol. The association with negatively charged membranes is much stronger and much less sensitive to membrane curvature, phase, and cholesterol content. The presence of unsaturated lipids increases binding in all cases. These findings provide insight into the relation between membrane physical properties and AS binding affinity and dynamics that presumably define protein localization in vivo and, thereby, the role of AS in the physiopathology of Parkinson disease.