Solution structure of the integral human membrane protein VDAC-1 in detergent micelles

The voltage-dependent anion channel (VDAC) mediates trafficking of small molecules and ions across the eukaryotic outer mitochondrial membrane. VDAC also interacts with antiapoptotic proteins from the Bcl-2 family, and this interaction inhibits release of apoptogenic proteins from the mitochondrion. We present the nuclear magnetic resonance (NMR) solution structure of recombinant human VDAC-1 reconstituted in detergent micelles. It forms a 19-stranded beta barrel with the first and last strand parallel. The hydrophobic outside perimeter of the barrel is covered by detergent molecules in a beltlike fashion. In the presence of cholesterol, recombinant VDAC-1 can form voltage-gated channels in phospholipid bilayers similar to those of the native protein. NMR measurements revealed the binding sites of VDAC-1 for the Bcl-2 protein Bcl-x(L), for reduced beta-nicotinamide adenine dinucleotide, and for cholesterol. Bcl-x(L) interacts with the VDAC barrel laterally at strands 17 and 18.     

Oscillatory thermomechanical instability of an ultrathin catalyst

Because of the small thermal capacity of ultrathin ( approximately 200 nanometers) metal single crystals, it is possible to explore the coupling of catalytic and thermal action at low pressures. We analyzed a chemothermomechanical instability in this regime, in which catalytic reaction kinetics interact with heat transfer and mechanical buckling to create oscillations. These interacting components are separated and explored through experimentation, mathematical modeling, and scientific computation, and an explanation of the phenomenon emerges from their synthesis.     

Cassini imaging of Jupiter's atmosphere,satellites, and rings

The Cassini Imaging Science Subsystem acquired about 26,000 images of the Jupiter system as the spacecraft encountered the giant planet en route to Saturn. We report findings on Jupiter's zonal winds, convective storms, low-latitude upper troposphere, polar stratosphere, and northern aurora. We also describe previously unseen emissions arising from Io and Europa in eclipse, a giant volcanic plume over Io's north pole, disk-resolved images of the satellite Himalia, circumstantial evidence for a causal relation between the satellites Metis and Adrastea and the main jovian ring, and information on the nature of the ring particles.     

VelB/VeA/LaeA complex coordinates light signal with fungal development and secondary metabolism

Differentiation and secondary metabolism are correlated processes in fungi that respond to light. In Aspergillus nidulans, light inhibits sexual reproduction as well as secondary metabolism. We identified the heterotrimeric velvet complex VelB/VeA/LaeA connecting light-responding developmental regulation and control of secondary metabolism. VeA, which is primarily expressed in the dark, physically interacts with VelB, which is expressed during sexual development. VeA bridges VelB to the nuclear master regulator of secondary metabolism, LaeA. Deletion of either velB or veA results in defects in both sexual fruiting-body formation and the production of secondary metabolites.     

Interhemispheric ice-sheet synchronicity during the Last Glacial Maximum

The timing of the last maximum extent of the Antarctic ice sheets relative to those in the Northern Hemisphere remains poorly understood. We develop a chronology for the Weddell Sea sector of the East Antarctic Ice Sheet that, combined with ages from other Antarctic ice-sheet sectors, indicates that the advance to and retreat from their maximum extent was within dating uncertainties synchronous with most sectors of Northern Hemisphere ice sheets. Surface climate forcing of Antarctic mass balance would probably cause an opposite response, whereby a warming climate would increase accumulation but not surface melting. Our new data support teleconnections involving sea-level forcing from Northern Hemisphere ice sheets and changes in North Atlantic deep-water formation and attendant heat flux to Antarctic grounding lines to synchronize the hemispheric ice sheets.     

Potential for chemolithoautotrophy among ubiquitous bacteria lineages in the dark ocean

Recent studies suggest that unidentified prokaryotes fix inorganic carbon at globally significant rates in the immense dark ocean. Using single-cell sorting and whole-genome amplification of prokaryotes from two subtropical gyres, we obtained genomic DNA from 738 cells representing most cosmopolitan lineages. Multiple cells of Deltaproteobacteria cluster SAR324, Gammaproteobacteria clusters ARCTIC96BD-19 and Agg47, and some Oceanospirillales from the lower mesopelagic contained ribulose-1,5-bisphosphate carboxylase-oxygenase and sulfur oxidation genes. These results corroborated community DNA and RNA profiling from diverse geographic regions. The SAR324 genomes also suggested C(1) metabolism and a particle-associated life-style. Microautoradiography and fluorescence in situ hybridization confirmed bicarbonate uptake and particle association of SAR324 cells. Our study suggests potential chemolithoautotrophy in several uncultured Proteobacteria lineages that are ubiquitous in the dark oxygenated ocean and provides new perspective on carbon cycling in the ocean's largest habitat.     

Determining soil water‐balance components using an irrigated grass lysimeter in NE Austria

The water balance of a certain soil profile in a certain time interval is subjected to changes of soil water content within the respective profile, and fluxes at its upper and lower boundary. Weighing lysimeters are valuable instruments for water‐balance studies. Typically, mass changes—thus, changes of soil profile water content—are detected by a weighing system, while seepage water outflow is measured by a tipping bucket, and precipitation data originate from a rain gauge. Hence, evapotranspiration as unknown component can be determined by solving a simple water‐balance equation. However, using separately measured precipitation data may cause implausible (negative) evapotranspiration. In this study, change of soil profile water content, seepage water, precipitation, and evapotranspiration were determined directly from 10‐min lysimeter data from 2011. Precipitation measured with the lysimeter was in total 20% greater than rain‐gauge values. Even dew formation was measured and considered as water‐balance component; however, its total amount was rather low. Evapotranspiration calculated on daily and hourly base indicated a sound correlation with measured data, but measured values were considerably smaller. Both calculated and measured dew amount were of the same magnitude. Comparison of lysimeter evapotranspiration with daily calculations (neglecting dew) and hourly computation (considering dew) delivered similar results. Generally, the utilized lysimeter facility and the specific data management provided sound water‐balance components with high accuracy and temporal resolution, respectively.     

Bud development and dormancy in slash and loblolly pine. I. Speed of budbreak and second year height as related to lifting date

Slash and loblolly pine 1-0 seedlings were lifted from the nurserybed in late November, mid-December, late December, and mid-February. The buds of the seedlings were classified as set or growing two weeks prior to lifting and were re-examined upon lifting. For both species, buds that had set remained set whereas those that were classified as growing showed an decreasing trend of setting from November through December. A subset of seedlings was potted and maintained in a greenhouse to determine rate of budbreak; the remainder were field planted. In the greenhouse, loblolly pine broke bud fastest and slowest when lifted in mid-February and mid-December, respectively. The rate of slash pine budbreak increased over successive lifting dates. In the field, loblolly pine lifted in mid-December exhibited the highest percentage of growing seedlings; these seedlings were also tallest after one year in the field. Field-planted slash pine had the highest percentage of growing seedlings when lifted in late November. However, seedlings lifted in mid-December were tallest after one year.