Enriched Pt-Re-Os isotope systematics in plume lavas explained by metasomatic sulfides

To explain the elevated osmium isotope (186Os-187Os) signatures in oceanic basalts, the possibility of material flux from the metallic core into the crust has been invoked. This hypothesis conflicts with theoretical constraints on Earth's thermal and dynamic history. To test the veracity and uniqueness of elevated 186Os-187Os in tracing core-mantle exchange, we present highly siderophile element analyses of pyroxenites, eclogites plus their sulfides, and new 186Os/188Os measurements on pyroxenites and platinum-rich alloys. Modeling shows that involvement in the mantle source of either bulk pyroxenite or, more likely, metasomatic sulfides derived from either pyroxenite or peridotite melts can explain the 186Os-187Os signatures of oceanic basalts. This removes the requirement for core-mantle exchange and provides an effective mechanism for generating Os isotope diversity in basalt source regions.     

Gas adsorption sites in a large-pore metal-organic framework

The primary adsorption sites for Ar and N2 within metal-organic framework-5, a cubic structure composed of Zn4O(CO2)6 units and phenylene links defining large pores 12 and 15 angstroms in diameter, have been identified by single-crystal x-ray diffraction. Refinement of data collected between 293 and 30 kelvin revealed a total of eight symmetry-independent adsorption sites. Five of these are sites on the zinc oxide unit and the organic link; the remaining three sites form a second layer in the pores. The structural integrity and high symmetry of the framework are retained throughout, with negligible changes resulting from gas adsorption.     

Long-range interactions within a nonnative protein

Protein folding and unfolding are coupled to a range of biological phenomena, from the regulation of cellular activity to the onset of neurodegenerative diseases. Defining the nature of the conformations sampled in nonnative proteins is crucial for understanding the origins of such phenomena. We have used a combination of nuclear magnetic resonance (NMR) spectroscopy and site-directed mutagenesis to study unfolded states of the protein lysozyme. Extensive clusters of hydrophobic structure exist within the wild-type protein even under strongly denaturing conditions. These clusters involve distinct regions of the sequence but are all disrupted by a single point mutation that replaced residue Trp62 with Gly located at the interface of the two major structural domains in the native state. Thus, nativelike structure in the denatured protein is stabilized by the involvement of Trp62 in nonnative and long-range interactions.     

Curcumin, a major constituent of turmeric, corrects cystic fibrosis defects

Cystic fibrosis is caused by mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR). The most common mutation, DeltaF508, results in the production of a misfolded CFTR protein that is retained in the endoplasmic reticulum and targeted for degradation. Curcumin is a nontoxic Ca-adenosine triphosphatase pump inhibitor that can be administered to humans safely. Oral administration of curcumin to homozygous DeltaF508 CFTR mice in doses comparable, on a weight-per-weight basis, to those well tolerated by humans corrected these animals' characteristic nasal potential difference defect. These effects were not observed in mice homozygous for a complete knockout of the CFTR gene. Curcumin also induced the functional appearance of DeltaF508 CFTR protein in the plasma membranes of transfected baby hamster kidney cells. Thus, curcumin treatment may be able to correct defects associated with the homozygous expression of DeltaF508 CFTR.     

Effects of Simulated Acid Mist on a Sitka Spruce Forest Approaching Canopy Closure: Significance of Acidified Versus Non-Acidified Nitrogen Inputs

Effects of enhanced N, S and NS Acid additions, up to approximately 100 kg N and S ha^?1 y^?1, are described for a 15-year-old Sitka spruce forest growing on an acid peat in Scotland. Groups of 10 trees, replicated over 4 blocks, have been treated at canopy height on approximately 50 or 100 occasions with 2 mm precipitation equivalent, between April and November, since 1996. Relative stem volume increment (RSVI) has been consistently higher in the NS Acid treated trees compared with control or N treated trees since the second year of treatment, although no dose response was found. Litterfall was also considerably increased in the NS Acid treatments and showed a clear dose effect but was not correlated with RSVI. Base cation concentrations in soil waters, collected using zero tension lysimeters reflected the presence or absence of the spray treatments and showed a dose related increase in response to NS Acid inputs. Treatment with 2NS Acid increased NH₄-N and NO₃-N by an order of magnitude. Results after 4 years of treatment showed a positive growth and litterfall response to NS Acid inputs but no effect of N alone. Enhanced stemwood growth may be linked to the higher base cation and phosphate concentrations measured in the soil water in the presence of NS Acid and S treatments.     

Polyacetylenes from the Apiaceae vegetables carrot, celery, fennel, parsley, and parsnip and their cytotoxic activities

A dichloromethane extract of root celery yielded falcarinol, falcarindiol, panaxydiol, and the new polyacetylene 8-O-methylfalcarindiol. The structure of the new compound was established by one- and two-dimensional (1D and 2D) NMR, mass spectrometry, and optical rotation data. Nonpolar extracts of roots and bulbs of carrots, celery, fennel, parsley, and parsnip were investigated for their content of polyacetylenes by high-performance liquid chromatography with diode array detection (HPLC-DAD). All five species contained polyacetylenes, although carrots and fennel only in minor amounts. Additionally, the cytotoxicity of the four polyacetylenes against five different cell lines was evaluated by the annexin V-PI assay. Falcarinol proved to be the most active compound with a pronounced toxicity against acute lymphoblastic leukemia cell line CEM-C7H2, with an IC(50) of 3.5 micromol/L. The possible chemopreventive impact of the presented findings is discussed briefly.