FRCaMP,a Red Fluorescent Genetically Encoded Calcium Indicator Based on Calmodulin from Schizosaccharomyces Pombe Fungus

Red fluorescent genetically encoded calcium indicators (GECIs) have expanded the available pallet of colors used for the visualization of neuronal calcium activity in vivo. However, their calcium-binding domain is restricted by calmodulin from metazoans. In this study, we developed red GECI, called FRCaMP, using calmodulin (CaM) from Schizosaccharomyces pombe fungus as a calcium binding domain. Compared to the R-GECO1 indicator in vitro, the purified protein FRCaMP had similar spectral characteristics, brightness, and pH stability but a 1.3-fold lower ΔF/F calcium response and 2.6-fold tighter calcium affinity with K_d of 441 nM and 2.4–6.6-fold lower photostability. In the cytosol of cultured HeLa cells, FRCaMP visualized calcium transients with a ΔF/F dynamic range of 5.6, which was similar to that of R-GECO1. FRCaMP robustly visualized the spontaneous activity of neuronal cultures and had a similar ΔF/F dynamic range of 1.7 but 2.1-fold faster decay kinetics vs. NCaMP7. On electrically stimulated cultured neurons, FRCaMP demonstrated 1.8-fold faster decay kinetics and 1.7-fold lower ΔF/F values per one action potential of 0.23 compared to the NCaMP7 indicator. The fungus-originating CaM of the FRCaMP indicator version with a deleted M13-like peptide did not interact with the cytosolic environment of the HeLa cells in contrast to the metazoa-originating CaM of the similarly truncated version of the GCaMP6s indicator with a deleted M13-like peptide. Finally, we generated a split version of the FRCaMP indicator, which allowed the simultaneous detection of calcium transients and the heterodimerization of bJun/bFos interacting proteins in the nuclei of HeLa cells with a ΔF/F dynamic range of 9.4 and a contrast of 2.3–3.5, respectively.     

Kinetics of the formation of titanium oxynitride and nitride under the action of VUV, studied by means of ellipsometry

Preparation of thin nanolayers (approximately 10 nm) with the required stoichiometry and minimal grain size is important for the development of nanostructures. The kinetics of the formation of titanium nitride and titanium oxynitride layers through nitridation of the titanium matrix was investigated in the present work. It was shown that the UV radiation causes an increase in nitridation rate, depending on radiation energy, within the studied range 4 to 21 eV. The investigation was carried out with the help of ellipsometry and independent methods: atomic force microscopy, electron microscopy, and X-ray photoelectron spectroscopy. The mechanism of titanium interaction with nitrogen resulting in the formation of nitride and oxynitride layers at the Si/Ti and SiO2/Ti interfaces was investigated, the role of the UV radiation in solid-state reactions was revealed, and the mechanism of the process was proposed on the basis of the experimental data and results of quantum chemical simulation. The use of UV radiation allowed us to obtain the layers at low temperatures (0-5 degrees C) and to achieve a short reaction time due to an increase in reaction rate. The resulting layers have good masking properties (minimal density of pores and defects, high smoothness of the surface). This allows one to use these layers for chemical and electronic passivation and stabilization of the surface of semiconductor nano-objects (quantum dots, quantum wires, nanowhiskers etc.) for electronic and photon nanodevices.     

BOOK REVIEW

ABSTRACT

A previous paper reported the effect of increasing concentrations of hydrofluoric, oxalic, sulfuric and phosphoric acids at three fixed HCl or HNO₃ concentrations on the retention of Am(III), Th(IV) or Np(IV), and U(VI) by the new chelating ion-exchange resin Diphonix?. In this paper the metal uptake data have been analyzed by calculating the effect that complex formation in solution has on the overall metal uptake by the resin. The calculations performed have allowed us to conclude that in most cases the uptake of Am(III) and U(VI) by Diphonix can be explained by assuming that only the uncomplexed metal cation is sorbed. With tetravalent actinides, on the contrary, the uptake data can only be explained if the simultaneous sorption of the uncomplexed cation and of neutral metal complexes is assumed. Indirect evidence has also been obtained on the existence of anionic fluoride complexes of Np(IV). In all other cases, with minor exceptions, the complex formation data available in the literature seem to describe accurately the behavior of the investigated systems.     

Planar Graph Coloring Avoiding Monochromatic Subgraphs: Trees and Paths Make It Difficult

We consider the problem of coloring a planar graph with the minimum number of colors so that each color class avoids one or more forbidden graphs as subgraphs. We perform a detailed study of the computational complexity of this problem. We present a complete picture for the case with a single forbidden connected (induced or noninduced) subgraph. The 2-coloring problem is NP-hard if the forbidden subgraph is a tree with at least two edges, and it is polynomially solvable in all other cases. The 3-coloring problem is NP-hard if the forbidden subgraph is a path with at least one edge, and it is polynomially solvable in all other cases. We also derive results for several forbidden sets of cycles. In particular, we prove that it is NP-complete to decide if a planar graph can be 2-colored so that no cycle of length at most 5 is monochromatic.     

Spin Polarization in Single Spin Experiments on Defects in Diamond

Generation of pure spin states is an important step towards coherent control of single spin systems. Especially for nitrogen-vacancy defects in diamond, where readout of single spins using optical detection is available, fast initialization of spin is significant in the context of quantum computing applications. In this system the spin polarization is caused by an intersystem crossing process via the meta-stable singlet state ¹ . The slowest relaxation rate is the intersystem to the triplet ground-state ³ on a timescale of 400 ns. The intersystem crossing process mainly populates the ms = 0 spin sublevels of the paramagnetic ground state. Although no direct nuclear spin polarization is seen for low magnetic fields, frequency selective microwave pulses can be used to transfer electron spin polarization to ¹³C nuclear spin states.     

Automating Mashups for Next-Generation Enterprise Portals

The increasing number of resources available through portals establish a need to tailor information to individual needs and situations. Mashups are tools for dynamically integrating independent applications. For portals, what is needed are means to automatically create personalized mashups that optimally fit a user's information needs in a given situation. At the core of our approach are different ontology-based models that describe the user, the domain, possible information needs in this domain, and personalization rules determining which information to present to which user in which situation.