Description: The properties of snow on East Antarctic sea ice off Wilkes Land were examined during the Sea Ice Physics and Ecosystem Experiment (SIPEX) in late winter of 2007, focusing on the interaction with sea ice. This observation includes 11 transect lines for the measurement of ice thickness, freeboard, and snow depth, 50 snow pits on 13 ice floes, and diurnal variation of surface heat flux on three ice floes. The detailed profiling of topography along the transects and the d18O, salinity, and density datasets of snow made it possible to examine the snow-sea-ice interaction quantitatively for the first time in this area. In general, the snow displayed significant heterogeneity in types, thickness (mean: 0.14 +- 0.13 m), and density (325 +- 38 kg/m**3), as reported in other East Antarctic regions. High salinity was confined to the lowest 0.1 m. Salinity and d18O data within this layer revealed that saline water originated from the surface brine of sea ice in 20% of the total sites and from seawater in 80%. From the vertical profiles of snow density, bulk thermal conductivity of snow was estimated as 0.15 W/K/m on average, only half of the value used for numerical sea-ice models. Although the upward heat flux within snow estimated with this value was significantly lower than that within ice, it turned out that a higher value of thermal conductivity (0.3 to 0.4 W/K/m) is preferable for estimating ice growth amount in current numerical models. Diurnal measurements showed that upward conductive heat flux within the snow and net long-wave radiation at the surface seem to play important roles in the formation of snow ice from slush. The detailed surface topography allowed us to compare the air-ice drag coefficients of ice and snow surfaces under neutral conditions, and to examine the possibility of the retrieval of ice thickness distribution from satellite remote sensing. It was found that overall snow cover works to enhance the surface roughness of sea ice rather than moderate it, and increases the drag coefficient by about 10%. As for thickness retrieval, mean ice thickness had a higher correlation with ice surface roughness than mean freeboard or surface elevation, which indicates the potential usefulness of satellite L-band SAR in estimating the ice thickness distribution in the seasonal sea-ice zone.

Description: We report on observations of dense shelf water overflows and Antarctic Bottom Water (AABW) formation along the continental margin of the Adelie and George V Land coast between 140°E and 149°E. Vertical sections and bottom layer water mass properties sampled during two RVIB Nathaniel B Palmer hydrographic surveys (NBP00-08, December 2000/January 2001 and NBP04-08, October 2004) describe the spreading of cold, dense shelf water on the continental slope and rise from two independent source regions. The primary source region is the Adelie Depression, exporting high-salinity dense shelf water through the Adelie Sill at 143°E. An additional eastern source region of lower-salinity dense shelf water from the Mertz Depression is identified for the first time from bottom layer properties northwest of the Mertz Sill and Mertz Bank (146°E-148°E) that extend as far as the Buffon Channel (144.75°E) in summer. Regional analysis of satellite-derived ice production estimates over the entire region from 1992 to 2005 suggests that up to 40% of the total ice production for the region occurs over the Mertz Depression and therefore this area is likely to make a significant contribution to the total dense shelf water export. Concurrent time series from bottom-mounted Microcats and ADCP instruments from the Mertz Polynya Experiment (April 1998 to May 1999) near the Adelie Sill and on the upper continental slope (1150 m) and lower continental rise (3250 m) to the north describe the seasonal variability in downslope events and their interaction with the ambient water masses. The critical density for shelf water to produce AABW is examined and found to be 27.85 kg/m**3 from the Adelie Depression and as low as 27.80 kg/m**3 from the Mertz Depression. This study suggests previous dense shelf water export estimates based on the flow through the Adelie Sill alone are conservative and that other regions around East Antarctica with similar ice production to the Mertz Depression could be contributing to the total AABW in the Australian-Antarctic Basin.

Description: Preliminary results are presented from the first validation of geophysical dataproducts (ice concentration, snow thickness on sea ice ( ) and ice temperature ( ) fromthe NASA EOS Aqua AMSR-E sensor, in East Antarctica (in September-October 2003). Thechallenge of collecting sufficient measurements with which to adequately validate thecoarse-resolution AMSR-E data products was addressed by means of a hierarchicalapproach, using detailed in situ measurements, digital aerial photography and other satellitedata. Initial results indicate that, at least under cold conditions with a dry snowcover, thereis a reasonably close agreement between satellite- and aerial photo-derived iceconcentrations i.e., 97.2 ±3.6% for NT2 and 96.5 ±2.5% for BBA algorithms versus 94.3±10% for the aerial photos. In general, the AMSR-E concentration represents a slightoverestimate of the actual concentration, with the largest discrepancies occurring in regionscontaining a relatively high proportion of thin ice. Although the AMSR-E concentrations fromthe NT2 and BBA algorithms are similar on average, differences of 〉5% occur on a point-by-point basis, again related to thin ice distribution. The AMSR-E ice temperature ( ) productagrees with coincident surface measurements to within approximately 0.5o C. Regardingsnow thickness, the AMSR retrieval is a significant underestimate compared to in situmeasurements weighted by the percentage of thin ice (and open water) present. For thecase study analysed, the underestimate was 46% for the overall average, but 23%compared to smooth ice measurements. An encouraging factor is that the spatialdistribution of the AMSR-E product follows an expected and consistent spatial pattern,suggesting that the observed difference may be an offset (at least under freezingconditions). Areas of discrepancy are identified, and the need for future work highlighted.

Description: Proteasomes execute the degradation of most cellular proteins. Although the 20S core particle (CP) has been studied in great detail, the structure of the 19S regulatory particle (RP), which prepares ubiquitylated substrates for degradation, has remained elusive. Here, we report the crystal structure of one of the RP subunits, Rpn6, and we describe its integration into the cryo-EM density map of the 26S holocomplex at 9.1 Å resolution. Rpn6 consists of an α-solenoid-like fold and a proteasome COP9/signalosome eIF3 (PCI) module in a right-handed suprahelical configuration. Highly conserved surface areas of Rpn6 interact with the conserved surfaces of the Pre8 (alpha2) and Rpt6 subunits from the alpha and ATPase rings, respectively. The structure suggests that Rpn6 has a pivotal role in stabilizing the otherwise weak interaction between the CP and the RP.

Description: Detection of an immature dentate gyrus feature in human schizophrenia/bipolar patients Translational Psychiatry 2, e135 (July 2012). doi:10.1038/tp.2012.56 Authors: N M Walton, Y Zhou, J H Kogan, R Shin, M Webster, A K Gross, C L Heusner, Q Chen, S Miyake, K Tajinda, K Tamura, T Miyakawa & M Matsumoto

Description: Motivation: Metabolic pathways are complex systems of chemical reactions taking place in every living cell to degrade substrates and synthesize molecules needed for life. Modeling the robustness of these networks with respect to the dysfunction of one or several reactions is important to understand the basic principles of biological network organization, and to identify new drug targets. While several approaches have been proposed for that purpose, they are computationally too intensive to analyze large networks, and do not properly handle reversible reactions. Results: We propose a new model — the flux balance impact degree — to model the robustness of large metabolic networks with respect to gene knock-out. We formulate the computation of the impact of one or several reaction blocking as linear programs, and propose efficient strategies to solve them. We show that the proposed method better predicts the phenotypic impact of single gene deletions on Escherichia coli than existing methods. Availability: https://sunflower.kuicr.kyoto-u.ac.jp/~tyoyo/fbid/index.html Contact: takutsu@kuicr.kyoto-u.ac.jp or Jean-Philippe.Vert@mines.org Supplementary information: Supplementary data are available at Bioinformatics online.