Development of tree-ring maximum latewood density chronologies for the western Tien Shan Mountains,China: Influence of detrending method and climate response

Three tree-ring maximum latewood density chronologies were developed from high elevation Picea schrenkiana sites in the western Tien Shan Mountains using different detrending methods. The new chronologies extend back to the early 16th and late 17th centuries, and contain significant late spring and summer temperature signals, respectively. An assessment of varying detrending methods and band-pass filtering the chronologies revealed only slightly differing low frequency trends retained in the maximum latewood densities. The distance between sampling sites and the varying seasonality of limiting climatic factors are identified as key drivers affecting the correlation among the maximum latewood density records in the study region. The new chronologies represent reliable proxies of high elevation late spring and summer temperature variability in an area underrepresented by such data, and are ready-to-use for network analyses addressing longer-term climate variations in eastern central Asia.     

Independent evolution of song diversity and song motor performance in canaries,goldfinches and allies indicates clade-specific trade-offs in birdsong

The diversity and the motor performance of birdsongs can both be sexually selected. In wood warblers, most species with high motor performance sing a greater proportion of trills, presumably to advertise performance, and thus have lower syllable diversity. We tested if this trade-off between motor performance and syllable diversity extends to canaries, goldfinches and allies, a clade with much longer and more varied songs. We assembled a molecular phylogeny and inferred song motor performance based on the speed of frequency modulation either in trills or in within-song intervals. The two metrics of performance were positively, but only mildly, related across species. While performance evaluated in intervals had high phylogenetic signal, performance evaluated in trills changed independently of phylogeny and was constrained by body size. Species in densely vegetated habitats sang fewer trills, but did not differ in motor performance. Contrary to wood warblers, song motor performance did not predict the proportion of trilled syllables nor within-song syllable diversity, perhaps because large differences in the song duration of canaries, goldfinches and allies prevent trills from severely compromising syllable diversity. Opposed results in wood warblers and in these finches indicate the existence of clade-specific trade-offs in the evolution of birdsong.     

Novel deletion mutation of TRPS1 gene in a Chinese patient of trichorhinophalangeal syndrome type I

Tricho–rhino–phalangeal syndrome (TRPS) is a rare autosomal dominant disorder. Deletion or mutation of the TRPS1 gene leads to the tricho–rhino–phalangeal syndromes type I or type III. In this article, we describe a Chinese patient affected with type I TRPS and showing prominent pilar, rhinal and phalangeal abnormalities. Mutational screening and sequence analysis of TRPS1 gene revealed a previously unidentified four-base-pair deletion of nucleotides 1783–1786 (c.1783_1786delACTT). The mutation causes a frame shift after codon 593, introducing a premature stop codon after 637 residues in the gene sequence. This deletion is an unquestionable loss-of-function mutation, deleting all the functionally important parts of the protein. Our novel discovery indicates that sparse hair and metacarpal defects of tricho–rhino–phalangeal syndromes in this patient are due to this TRPS1 mutation. And this data further supports the critical role of TRPS1 gene in hair and partial skeleton morphogenesis.     

Disorder and order in unfolded and disordered peptides and proteins: A view derived from tripeptide conformational analysis. II. Tripeptides with short side chains populating asx and β‐type like turn conformations

In the preceding paper, we found that ensembles of tripeptides with long or bulky chains can include up to 20% of various turns. Here, we determine the structural and thermodynamic characteristics of GxG peptides with short polar and/or ionizable central residues (D, N, C), whose conformational distributions exhibit higher than average percentage (>20%) of turn conformations. To probe the side‐chain conformations of these peptides, we determined the ³J(H^α,H^β) coupling constants and derived the population of three rotamers with χ₁‐angles of ?60°, 180° and 60°, which were correlated with residue propensities by DFT‐calculations. For protonated GDG, the rotamer distribution provides additional evidence for asx‐turns. A comparison of vibrational spectra and NMR coupling constants of protonated GDG, ionized GDG, and the protonated aspartic acid dipeptide revealed that side chain protonation increases the pPII content at the expense of turn populations. The charged terminal groups, however, have negligible influence on the conformational properties of the central residue. Like protonated GDG, cationic GCG samples asx‐turns to a significant extent. The temperature dependence of the UVCD spectra and ³J(H^NH^α) constants suggest that the turn populations of GDG and GNG are practically temperature‐independent, indicating enthalpic and entropic stabilization. The temperature‐independent J‐coupling and UVCD spectra of GNG require a three‐state model. Our results indicate that short side chains with hydrogen bonding capability in GxG segments of proteins may serve as hinge regions for establishing compact structures of unfolded proteins and peptides. Proteins 2013. © 2012 Wiley Periodicals, Inc.     

Molecular structure,spectroscopic (FT-IR,FT-Raman,UV–vis), NBO,thermochemistry analysis of bis(thiourea)zinc(II) chloride crystals

The experimental and theoretical studies on the molecular structure and vibrational spectra of bis(thiourea)zinc(II) chloride (BTZC) crystals were investigated. The Fourier transform infrared, Fourier transform Raman and UV–vis spectra of BTZC were recorded. The molecular geometry and vibrational frequencies of BTZC in the ground state were calculated by using B3LYP with LANL2DZ as basis set. Comparison of the observed structural parameters of BTZC with single-crystal X-ray studies yields a good agreement. Vibrational analysis of the simultaneous IR and Raman activation of the Zn–Cl stretching mode in the molecule provides the evidence for the charge transfer interaction taking place within the molecule. The energy and oscillator strength are calculated by time-dependent density functional theory. The simulated spectra satisfactorily coincide with the experimental spectra.     

Molecular structure,vibrational spectroscopic,NBO and HOMO–LUMO studies of 2-amino 6-bromo 3-formylchromone

A systematic quantum mechanical study of the possible conformations and vibrational spectra of 2-amino 6-bromo 3-formylchromone has been reported. The equilibrium geometry, harmonic vibrational frequencies, infrared intensities and activities of Raman scattering were calculated by Hartree–Fock and density functional theory employing Becke's three-parameter (local, non-local and HF) hybrid exchange functionals with Lee–Yang–Parr co-relational (B3LYP) functionals using 6-311++G(d,p) basis set with complete relaxation in the potential energy surface. The calculated wavenumbers after proper scaling show a very good agreement with the observed values. The electrostatic potential mapped onto isodensity surface has been obtained. The natural bond orbital analysis has been carried out in order to study the intra-molecular bonding, interactions among bonds and delocalisation of unpaired electrons. The highest occupied molecular orbital–lowest unoccupied molecular orbital studies have been conducted in order to determine the way the molecule interacts with other species.     

Molecular structure,vibrational spectra and HOMO,LUMO analysis of 4-piperidone by density functional theory and ab initio Hartree–Fock calculations

Vibrational frequencies and geometrical parameters of 4-piperidone (4-PID) in the ground state have been calculated by using the Hartree–Fock (HF) and density functional methods (B3LYP) with 6-311++G(d,p) and 6-311+G(3df,2p) basis sets. These methods are proposed as a tool to be applied in the structural characterisation of 4-PID (C₅H₉NO). The title molecule has C _s point group symmetry, thus providing useful support in the interpretation of experimental IR and Raman data. The DFT-B3LYP/6-311+G(3df,2p) calculations have been found more reliable than the ab initio HF/6-311++G(d,p) calculations for the vibrational study of 4-PID. The calculated highest occupied molecular orbital and lowest unoccupied molecular orbital energies show that charge transfer occurs within the molecule. The theoretical spectrograms for FT-IR and FT-Raman spectra of the title molecule have been constructed.     

FT-IR,FT-Raman spectra and DFT vibrational analysis of 2-aminobiphenyl

In this work, the Fourier transform infrared (FT-IR) and Fourier transform Raman (FT-Raman) spectra of 2-aminobiphenyl (2ABP) were recorded in the solid phase. The optimised geometry, frequency and intensity of the vibrational bands of 2ABP were obtained by the density functional theory (BLYP and B3LYP) methods with complete relaxation in the potential energy surface using 6-31G(d) basis set. The harmonic vibrational frequencies were calculated and the scaled values have been compared with experimental FT-IR and FT-Raman spectra. The observed and the calculated frequencies are found to be in good agreement. The experimental spectra also coincide satisfactorily with those of theoretically constructed spectrograms.     

Conformational Equilibria of Bridled Chiroporphyrins in Solution Investigated by Vibrational Circular Dichroism

A series of bridled chiroporphyrins (BCP) and their metal complexes were prepared, in which two n‐methylene straps connect adjacent meso substituents by ester linkages. These compounds can exist as four atropisomers (αααα, αβαβ, αααβ, or ααββ) depending on the position of the meso groups relative to the macrocycle (α when above and β when below). We characterized the conformation of these chiral porphyrins and their metal (Zn, Ni, Mn) complexes by vibrational circular dichroism (VCD) associated with ab initio calculations. VCD spectra of the three metalloporphyrins were recorded in CDCl₃ and benzene solutions and ab initio calculations of their four atropoisomers were performed at the Density Functional Theory (DFT) level. The bridled chiroporphyrin with the longer straps (9 CH₂) and its nickel(II) complex can be isolated as the αβαβ atropisomer in the solid state and were found with the same conformation in CDCl₃ and benzene solutions. The bridled chiroporphyrin with the shortest straps (8 CH₂) and its zinc(II) complex can be isolated as the αααα atropisomer in the solid state, but in solution they are subject to atropisomeric equilibria, resulting in atropisomer distributions that are strongly solvent‐dependent. Comparison of the experimental VCD spectra with the predicted spectra of the four atropisomers allowed the quantification of these distributions. Finally, the manganese(III) complex also exhibits an atropisomeric equilibria in solution which is slightly solvent‐dependent. Chirality 25:480–486, 2013. © 2013 Wiley Periodicals, Inc.     

Absolute Configuration and Predominant Conformations of a Chiral Crown Ether‐Based Colorimetric Sensor: A Vibrational Circular Dichroism Spectroscopy and DFT Study of Chiral Recognition

In the present work, we report a comprehensive vibrational circular dichroism (VCD) spectroscopic study of a chiral crown ether which features an axial chiral 3.3'‐diphenyl‐1,1'‐binaphthyl group as chiral moiety. By comparing the experimental and calculated VCD spectra, we show that the presumably very flexible crown ether preferably adopts only one ring conformation. Conformational flexibility is observed in the 2,4‐dinitrophenyl‐diazophenol group, which was previously introduced for colorimetric detection of primary amines and amino alcohols (Cho et al., Chirality 2011;23:349–353). The VCD spectra of the host–guest complexes with phenyl glycinol (PG) and phenyl alaninol have been studied as well. Based on the spectra calculated, it is shown that the diastereomeric complexes in general can be differentiated using VCD spectroscopy. Furthermore, the experimental VCD spectra of the complexes of the host molecule with PG support the above finding. Chirality 25:294–300, 2013. © 2013 Wiley Periodicals, Inc.