Highly sensitive non‐isotopic restriction endonuclease fingerprinting of nucleotide variability in the gp60 gene within Cryptosporidium species,genotypes and subgenotypes infective to humans,and its implications

The high‐resolution analysis of genetic variation has major implications for the identification of parasites and micro‐organisms to species and subspecies as well as for population genetic and epidemiological studies. In this study, we critically assessed the effectiveness of a PCR‐based restriction endonuclease fingerprinting (REF) method for the detection of mutations in the 60 kDa glycoprotein gene (gp60) of Cryptosporidium, a genus of parasitic protists of major human and animal health importance globally. This gene displays substantial intraspecific variability in sequence, particularly in a TCA (perfect and imperfect) microsatellite region, is present as a single copy in the nuclear genome and is used widely as a marker in molecular epidemiological studies of Cryptosporidium hominis and C. parvum, the two predominant species that infect humans. The results of this study demonstrated an exquisite capacity of REF to detect nucleotide variability in the gp60 gene within each of the two species. The differentiation of genotypes/subgenotypes based on REF analysis was supported by targeted sequencing, allowing the detection of levels of variation as low as a single‐nucleotide transversion for amplicons of ∼1 kb in size. The high‐throughput potential and relatively low‐cost of REF make it a particularly useful tool for large‐scale genetic analyses of C. hominis and C. parvum. REF could also be utilized for comparative surveys of genetic variability across large nuclear genomic regions. Such analyses of Cryptosporidium in clinical and environmental samples by REF have important implications for identifying sources of infection, modes of transmission and/or possible infectivity to humans, thus assisting in the surveillance and control of cryptosporidiosis. Given its excellent mutation detection capacity, REF should find broad applicability to various single‐copy genes as well as a wide range of other protozoan and metazoan parasites. (The nucleotide sequences reported in this article are available in the GenBank database under accession numbers GU214343–GU214371).     

Universal abelian covers of superisolated singularities

We give explicit examples of Gorenstein surface singularities with integral homology sphere link, which are not complete intersections. Their existence was shown by Luengo–Velasco, Melle–Hernández and Némethi, thereby providing counterexamples to the universal abelian covering conjecture of Neumann and Wahl (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Copper-mediated N- and O-arylations with arylboronic acids in a continuous flow microreactor: a new avenue for efficient scalability

A continuous flow procedure has been elaborated for the copper(II)-mediated N- and O-arylation of a range of compounds with arylboronic acids using a commercial microreactor setup. The compounds could be continuously generated in good yields paving the way for efficient scalability.     

Developments in liquid-crystalline dimers and oligomers

ABSTRACT

Liquid-crystalline dimers and bimesogens have attracted much attention due to their propensity to exhibit the spontaneously chiral twist-bend mesophase (N_TB), most often by dimers with methylene spacers. Despite their relative ease of synthesis, the number of ether-linked twist-bend materials significantly lags behind those of methylene-linked compounds. In this work, we have prepared and studied a range of ether-linked bimesogens homologous in structure to the FFO9OCB; as with methylene-linked systems, it appears that it is molecular topology and the gross molecular shape that are the primary drivers for the formation of this phase of matter. Dimers and bimesogens are well studied within the context of the twist-bend phase; however, present understanding of this mesophase in oligomeric systems lags far behind. We report our recent efforts to prepare further examples of oligomeric twist-bend nematogens, including further examples of our ‘n+1’ methodology, which may allow the synthesis of high-purity, monodisperse materials of any given length to be prepared. We have observed that there is a tendency for these materials to exhibit highly ordered soft-crystalline mesophases as opposed to the twist-bend phase.     

Heats of formation of C(6)H(5)(•), C(6)H(5)(+), and C(6)H(5)NO by threshold photoelectron photoion coincidence and active thermochemical tables analysis

Threshold photoelectron photoion coincidence has been used to prepare selected internal energy distributions of nitrosobenzene ions [C(6)H(5)NO(+)]. Dissociation to C(6)H(5)(+) + NO products was measured over a range of internal energies and rate constants from 10(3) to 10(7) s(-1) and fitted with the statistical theory of unimolecular decay. A 0 K dissociative photoionization onset energy of 10.607 ± 0.020 eV was derived by using the simplified statistical adiabatic channel model. The thermochemical network of Active Thermochemical Tables (ATcT) was expanded to include phenyl and phenylium, as well as nitrosobenzene. The current ATcT heats of formation of these three species at 0 K (298.15 K) are 350.6 (337.3) ± 0.6, 1148.7 (1136.8) ± 1.0, and 215.6 (198.6) ± 1.5 kJ mol(-1), respectively. The resulting adiabatic ionization energy of phenyl is 8.272 ± 0.010 eV. The new ATcT thermochemistry for phenyl entails a 0 K (298.15 K) C-H bond dissociation enthalpy of benzene of 465.9 (472.1) ± 0.6 kJ mol(-1). Several related thermochemical quantities from ATcT, including the current enthalpies of formation of benzene, monohalobenzenes, and their ions, as well as interim ATcT values for the constituent atoms, are also given.     

Overconvergent modular sheaves and modular forms for GL 2/F

Given a totally real field F and a prime integer p which is unramified in F, we construct p-adic families of overconvergent Hilbert modular forms (of non-necessarily parallel weight) as sections of, so called, overconvergent Hilbert modular sheaves. We prove that the classical Hilbert modular forms of integral weights are overconvergent in our sense. We compare our notion with Katz’s definition of p-adic Hilbert modular forms. For F = ?, we prove that our notion of (families of) overconvergent elliptic modular forms coincides with those of R. Coleman and V. Pilloni.     

Ethynyl and Propynylpyrene Inhibitors of Cytochrome P450

Abstract  

The single-crystal X-ray structures and in vivo activities of three aryl acetylenic inhibitors of cytochromes P450 1A1, 1A2, 2A6, and 2B1 have been determined and are reported herein. These are 1-ethynylpyrene, 1-propynylpyrene, and 4-propynylpyrene. To investigate electronic influences on the mechanism of enzyme inhibition, the experimental electron density distribution of 1-ethynylpyrene has been determined using low-temperature X-ray diffraction measurements, and the resulting net atomic charges compared with various theoretical calculations. A total of 82,390 reflections were measured with Mo Kα radiation to a (sinθ/λ)_max = 0.985 Å⁻¹. Averaging symmetry equivalent reflections yielded 8,889 unique reflections. A least squares refinement procedure was used in which multipole parameters were added to describe the distortions of the atomic electron distributions from spherical symmetry. A map of the model electron density distribution of 1-ethynylpyrene was obtained. Net atomic charges calculated from refined monopole population parameters yielded charges that showed that the terminal acetylenic carbon atom (C18) is more negative than the internal carbon (C17). Net atomic charges calculated by ab initio, density functional theory, and semi-empirical methods are consistent with this trend suggesting that the terminal acetylenic carbon atom is more likely to be the site of oxidation. This is consistent with the inhibition mechanism pathway that results in the formation of a reactive ketene intermediate. This is also consistent with assay results that determined that 1-ethynylpyrene acts as a mechanism-based inhibitor of P450s 1A1 and 1A2 and as a reversible inhibitor of P450 2B1. Crystallographic data: 1-ethynylpyrene, C₁₈H₁₀, P2₁/c, a = 14.571(2) Å, b = 3.9094(5) Å, c = 20.242(3) Å, β = 105.042(2)°, V = 1,113.5(2) Å³; 1-propynylpyrene, C₁₉H₁₂, P2₁/n, a = 8.970(2) Å, b = 10.136(1) Å, c = 14.080(3) Å, β = 99.77(2)°, V = 1,261.5(4) Å³; 4-propynylpyrene, C₁₉H₁₂, Pbca, a = 9.904(1) Å, b = 13.174(2) Å, c = 19.401(1) Å, V = 2,531.4(5) Å³.     

Synthesis,characterization, and star polymer assembly of boronic acid end‐functionalized polycaprolactone

Boronic acid end‐functionalized polycaprolactone (PCL) polymers were synthesized by ring‐opening polymerization using a pinacol boronate ester‐containing (Bpin) initiator. The polymerization provides access to boron‐terminated polymers (i.e. Bpin‐PCL‐OH) with narrow molecular weight distributions (PDI = 1.09). Postsynthetic manipulation of the polymer's terminal hydroxyl group by copper‐catalyzed azide‐alkyne cycloaddition chemistry provides a series of bis end‐functionalized polymers with significant structural diversity at the termini. Deprotection of the boronate ester end group was accomplished with an acidic solid phase DOWEX resin. The boronate ester deprotection methodology does not result in hydrolysis of the polymeric backbone. The boronic acid‐tipped polymers were converted into star polymer assemblies using thermal dehydration and ligand‐facilitated trimerization. Thermal dehydration of (HO)₂B‐PCL‐OAc to the corresponding boroxine‐based star polymer assembly was inefficient and lead to degradation products. Ligand‐facilitated trimerization using either pyridine or 7‐azaindole as the Lewis base was efficient and mild. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Inclusion Complexes of Gossypol with 2-Pentanone, 3-Pentanone, and 2-Hexanone

Inclusion complexes of gossypol with 2-pentanone, 3-pentanone, and 2-hexanone were prepared by crystallization from the corresponding ketone and hexane, and their structures were determined by low-temperature X-ray diffraction. All three compounds crystallize in monoclinic systems and have a 2:1 gossypol-to-solvent molar ratio. Both gossypol–pentanone complexes crystallize in C2/c space groups, and the solvent cavities in these structures have C₂ symmetry. The 3-pentanone molecule, which has C₂ symmetry, sits symmetrically within the cavity, while the 2-pentanone molecule, which lacks C₂ symmetry, takes two equally probable orientations within the cavity. Both structures are similar to previously reported gossypol inclusion complexes formed with small esters and 3-hexanone. The distal positioning of the carbonyl group in 2-hexanone does not allow it to fit into the same solvent cavity that exists in the pentanone structures. In the gossypol-2-hexanone complex, the solvent cages are skewed, and the C₂ site symmetry is lost. As a result, the structure crystallizes in a Cc space group and has a larger asymmetric unit and unit cell. Although the 2-hexanone structure retains many of the features of the gossypol–pentanone complexes, this is the first report of a gossypol inclusion compound with this extended structure.     

Ferrihydrite modification by boron doping

Application of the electrostatic ion storage ring ELISA to studies of clusters and biomolecules is discussed. Ions injected from a plasma source or a sputter source are hot, and at short times the yield of neutrals is usually dominated by decay of metastable ions. We have demonstrated that the decay function is close to a 1/t dependence when the internal energy of the ions is conserved, i.e., when photon emission can be ignored. Deviations from a 1/t distribution therefore gives information about the radiative lifetime or, for larger systems, about the intensity of the emitted radiation. Systematic measurements have been carried out for fullerene anions C _N ^?, for even values of N from 36 to 96, to test a classical dielectric model. Recently we have installed an electrospray ion source with a Paul trap for bunching, which can be used to inject biomolecular ions from solution, and the first experiments on laser spectroscopy of biomolecules have been carried out. Also lifetimes of excited states have been measured for stored biomolecular ions excited by a laser pulse.