Direct observation of Tomonaga-Luttinger-liquid state in carbon nanotubes at low temperatures

The electronic transport properties of conventional three-dimensional metals are successfully described by Fermi-liquid theory. But when the dimensionality of such a system is reduced to one, the Fermi-liquid state becomes unstable to Coulomb interactions, and the conduction electrons should instead behave according to Tomonaga-Luttinger-liquid (TLL) theory. Such a state reveals itself through interaction-dependent anomalous exponents in the correlation functions, density of states and momentum distribution of the electrons. Metallic single-walled carbon nanotubes (SWNTs) are considered to be ideal one-dimensional systems for realizing TLL states. Indeed, the results of transport measurements on metal-SWNT and SWNT-SWNT junctions have been attributed to the effects of tunnelling into or between TLLs, although there remains some ambiguity in these interpretations. Direct observations of the electronic states in SWNTs are therefore needed to resolve these uncertainties. Here we report angle-integrated photoemission measurements of SWNTs. Our results reveal an oscillation in the pi-electron density of states owing to one-dimensional van Hove singularities, confirming the one-dimensional nature of the valence band. The spectral function and intensities at the Fermi level both exhibit power-law behaviour (with almost identical exponents) in good agreement with theoretical predictions for the TLL state in SWNTs.     

ChiraSac Study on Chiral Spectroscopy and Photobiology

Weak interactions of molecules with solvents and/or environments are of crucial importance in material science and biology,but rather difficult to investigate quantitatively.Circular dichroism(CD)spectra reflect sensitively the conformational structures of chiral molecules,their(weak)interactions with solvents and/or proteins,etc.The SAC-CI method gives their CD spectra very reliably.     

Whole-genome sequencing of liver cancers identifies etiological influences on mutation patterns and recurrent mutations in chromatin regulators

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related death worldwide. We sequenced and analyzed the whole genomes of 27 HCCs, 25 of which were associated with hepatitis B or C virus infections, including two sets of multicentric tumors. Although no common somatic mutations were identified in the multicentric tumor pairs, their whole-genome substitution patterns were similar, suggesting that these tumors developed from independent mutations, although their shared etiological backgrounds may have strongly influenced their somatic mutation patterns. Statistical and functional analyses yielded a list of recurrently mutated genes. Multiple chromatin regulators, including ARID1A, ARID1B, ARID2, MLL and MLL3, were mutated in ～50% of the tumors. Hepatitis B virus genome integration in the TERT locus was frequently observed in a high clonal proportion. Our whole-genome sequencing analysis of HCCs identified the influence of etiological background on somatic mutation patterns and subsequent carcinogenesis, as well as recurrent mutations in chromatin regulators in HCCs.     

Positive and negative peptide signals control stomatal density

The stoma is a micro valve found on aerial plant organs that promotes gas exchange between the atmosphere and the plant body. Each stoma is formed by a strict cell lineage during the early stages of leaf development. Molecular genetics research using the model plant Arabidopsis has revealed the genes involved in stomatal differentiation. Cysteine-rich secretory peptides of the EPIDERMAL PATTERNING FACTOR-LIKE (EPFL) family play crucial roles as extracellular signaling factors. Stomatal development is orchestrated by the positive factor STOMAGEN/EPFL9 and the negative factors EPF1, EPF2, and CHALLAH/EPFL6 in combination with multiple receptors. EPF1 and EPF2 are produced in the stomatal lineage cells of the epidermis, whereas STOMAGEN and CHALLAH are derived from the inner tissues. These findings highlight the complex cell-to-cell and intertissue communications that regulate stomatal development. To optimize gas exchange, particularly the balance between the uptake of carbon dioxide (CO(2)) and loss of water, plants control stomatal activity in response to environmental conditions. The CO(2) level and light intensity influence stomatal density. Plants sense environmental cues in mature leaves and adjust the stomatal density of newly forming leaves, indicating the involvement of long-distance systemic signaling. This review summarizes recent research progress in the peptide signaling of stomatal development and discusses the evolutionary model of the signaling machinery.     

Hydrous olivine unable to account for conductivity anomaly at the top of the asthenosphere

The oceanic asthenosphere is observed to have high electrical conductivity, which is highly anisotropic in some locations. In the directions parallel and normal to the plate motion, the conductivity is of the order of 10(-1) and 10(-2) S m(-1), respectively, which cannot be explained by the conductivity of anhydrous olivine. But because hydrogen can be incorporated in olivine at mantle pressures, this observation has been attributed to olivine hydration, which might cause anisotropically high conductivity by proton migration. To examine this hypothesis, here we report the effect of water on electrical conductivity and its anisotropy for hydrogen-doped and undoped olivine at 500-1,500 K and 3 GPa. The hydrous olivine has much higher conductivity and lower activation energy than anhydrous olivine in the investigated temperature range. Nevertheless, extrapolation of the experimental results suggests that conductivity of hydrous olivine at the top of the asthenosphere should be nearly isotropic and only of the order of 10(-2) S m(-1). Our data indicate that the hydration of olivine cannot account for the geophysical observations, which instead may be explained by the presence of partial melt elongated in the direction of plate motion.     

Structural basis for recognition of acidic-cluster dileucine sequence by GGA1

GGAs (Golgi-localizing, gamma-adaptin ear homology domain, ARF-interacting proteins) are critical for the transport of soluble proteins from the trans-Golgi network (TGN) to endosomes/lysosomes by means of interactions with TGN-sorting receptors, ADP-ribosylation factor (ARF), and clathrin. The amino-terminal VHS domains of GGAs form complexes with the cytoplasmic domains of sorting receptors by recognizing acidic-cluster dileucine (ACLL) sequences. Here we report the X-ray structure of the GGA1 VHS domain alone, and in complex with the carboxy-terminal peptide of cation-independent mannose 6-phosphate receptor containing an ACLL sequence. The VHS domain forms a super helix with eight alpha-helices, similar to the VHS domains of TOM1 and Hrs. Unidirectional movements of helices alpha6 and alpha8, and some of their side chains, create a set of electrostatic and hydrophobic interactions for correct recognition of the ACLL peptide. This recognition mechanism provides the basis for regulation of protein transport from the TGN to endosomes/lysosomes, which is shared by sortilin and low-density lipoprotein receptor-related protein.     

Imaging plate illuminates many fields

The erasable phosphor imaging plate developed for medical radiography has found new uses in the laboratory. X-ray diffraction, protein crystallography and autoradiography have all benefited from this technology transfer from the clinic.