Intercellular communication: the Drosophila innexin multiprotein family of gap junction proteins

Gap junctions belong to the most conserved cellular structures in multicellular organisms, from Hydra to man. They contain tightly packed clusters of hydrophilic membrane channels connecting the cytoplasms of adjacent cells, thus allowing direct communication of cells and tissues through the diffusion of ions, metabolites, and cyclic nucleotides. Recent evidence suggests that gap junctions are constructed by three different families of four transmembrane proteins: the Connexins and the Innexins found in vertebrates and in invertebrates, respectively, and the Innexin-like Pannexins, which were recently discovered in humans. This article focuses on the Drosophila Innexin multiprotein family, which is comprised of eight members. We highlight common structural features and discuss recent findings that suggest close similarities in cellular distribution, function, and regulation of Drosophila Innexins and vertebrate gap junction proteins.     

Isonitrile trapping reactions under thermolysis of alkoxyamines for the synthesis of quinolines

[reaction: see text] An efficient tandem radical process comprising a thermal alkoxyamine homolysis, an isonitrile trapping reaction, a 5-exo-trig cyclization, and a homolytic aromatic substitution leads to substituted dihydroquinolines. Depending on the substituent R(1), oxidation to dihydro-1H-cyclopenta[b]quinolines (for R(1) = aryl) or tautomerization to tetrahydro-1H-cyclopenta[b]quinolines (for R(1) = CO(2)Me, CN) occurs. The heterocycles are obtained in moderate to good yields. Upon using microwave-induced heating, the reaction time can be shortened from 3 days to 30 min.     

Perturbations of positive semigroups on AM-spaces

We consider positive perturbations of positive semigroups on AM-spaces and prove a result which is the dual counterpart of a famous perturbation result of Desch in AL-spaces. As an application we present unbounded perturbations of the shift semigroup.     

Solvent Effects on the NMR Chemical Shifts of Imidazolium-Based Ionic Liquids and Cellulose Therein

The interactions of ionic liquids (IL) with solvents usually used in liquid-state nuclear magnetic resonance (NMR) spectroscopy are studied. The ¹H- and ¹³C-NMR chemical shift values of 1-n-butyl-3-methyl (BM)- and 1-ethyl-3-methyl (EM)-substituted imidazolium (IM) -chlorides (Cl) and -acetates (Ac) are determined before and after diluting with deuterated solvents (DMSO-d₆, D₂O, CD₃OD, and CDCl₃). The dilution offers structural modifications of the IL due to the solvents capacity to ionization. For further investigation of highly viscous cellulose dopes made of imidazolium-based IL, solid-state NMR spectroscopy enables the reproducibility of liquid-state NMR data of pure IL. The correlation of liquid- and solid-state NMR is shown on EMIM-Ac and cellulose/EMIM-Ac dope (10 wt %).     

The Transitive Minimum Manhattan Subnetwork Problem in 3 dimensions

We consider the Minimum Manhattan Subnetwork (MMSN) Problem which generalizes the already known Minimum Manhattan Network (MMN) Problem: Given a set P of n points in the plane, find shortest rectilinear paths between all pairs of points. These paths form a network, the total length of which has to be minimized. From a graph theoretical point of view, a MMN is a 1-spanner with respect to the L₁ metric. In contrast to the MMN problem, a solution to the MMSN problem does not demand L₁-shortest paths for all point pairs, but only for a given set R⊆P×P of pairs. The complexity status of the MMN problem is still unsolved in ≥2 dimensions, whereas the MMSN was shown to be NP-complete considering general relations R in the plane. We restrict the MMSN problem to transitive relations R_T (Transitive Minimum Manhattan Subnetwork (TMMSN) Problem) and show that the TMMSN problem in 3 dimensions is NP-complete.     

Using Goffman's concepts to explore collaborative interaction processes in elementary school mathematics

The present paper describes the combined implementation of two approaches which are based on the work of Erving Goffman and focus on the analysis of the interactional participation structures. Our aim is to examine the ways that differing interpretations of the ongoing interactions may lead the students to adopt differing roles, which in turn affects the process of negotiating and establishing shared meanings. For this purpose we analyse the interaction processes in one ‘expert’ group within the ‘Jigsaw’ form of cooperation (Aronson, 1978 Aronson, E. 1978. The jigsaw classroom, Beverly Hills, CA: Sage.  [Google Scholar]), decomposing the participants’ roles according to their interactional status and their interpersonal effect. Our analysis points out the different roles that emerge in the process of collaborative interaction, and the influence of these roles on group achievement and individual learning possibilities.     

Crystal Growth and Structure Determination of Pigment Orange 82

The crystal structure of the important industrial orange pigment PO82, major part of the BASF Colors & Effects^® product Sicopal^® Orange K/L 2430, was solved from combined X‐ray single crystal, X‐ray and neutron powder diffraction, ¹¹⁹Sn Mössbauer spectroscopy, transmission electron microscopy, electron diffraction, and chemical analyses. The structure contains Keggin type clusters composed of four [M₃O₁₃] trimers consisting each of three MO₆ octahedra that share edges and one common oxygen atom connecting the trimers to the central ZnO₄ tetrahedron. The octahedrally coordinated metal atom position is mixed occupied by Ti⁴⁺, Sn⁴⁺, and Zn²⁺. Adjacent Keggin clusters share vertices and are further interconnected to four ZnO₄ tetrahedra. This framework of interconnected MO₆ octahedra and ZnO₄ tetrahedra contains channels along [110], in which the Sn²⁺ cations are located.