Geology of the Caloris basin, Mercury: a view from MESSENGER

The Caloris basin, the youngest known large impact basin on Mercury, is revealed in MESSENGER images to be modified by volcanism and deformation in a manner distinct from that of lunar impact basins. The morphology and spatial distribution of basin materials themselves closely match lunar counterparts. Evidence for a volcanic origin of the basin's interior plains includes embayed craters on the basin floor and diffuse deposits surrounding rimless depressions interpreted to be of pyroclastic origin. Unlike lunar maria, the volcanic plains in Caloris are higher in albedo than surrounding basin materials and lack spectral evidence for ferrous iron-bearing silicates. Tectonic landforms, contractional wrinkle ridges and extensional troughs, have distributions and age relations different from their counterparts in and around lunar basins, indicating a different stress history.     

Fundamental issues in the geology and geophysics of venus

A number of important and currently unresolved issues in the global geology and geophysics of Venus will be addressable with the radar imaging, altimetry, and gravity measurements now forthcoming from the Magellan mission. Among these are the global volcanic flux and the rate of formation of new crust; the global heat flux and its regional variations; the relative importance of localized hot spots and linear centers of crustal spreading to crustal formation and tectonics; and the planform of mantle convection on Venus and the nature of the interactions among interior convective flow, near-surface deformation and magmatism.     

Molecular analysis of acute promyelocytic leukemia breakpoint cluster region on chromosome 17

Acute promyelocytic leukemia (APL; FAB M3) is characterized by a predominance of malignant promyelocytes that carry a reciprocal translocation between the long arms of chromosomes 15 and 17, t(15;17) (q22;q11.2-q12). This translocation has become diagnostic for APL, as it is present in almost 100 percent of cases. A Not I linking clone was used to detect this translocation initially on pulsed-field gel electrophoresis and subsequently with conventional Southern (DNA) analysis. The breakpoints in ten APL cases examined were shown to cluster in a 12-kb region of chromosome 17, containing two CpG-rich islands. The region is the first intron of the retinoic acid receptor alpha gene (RARA).     

Low-molecular-weight proteins related to Bence Jones proteins in multiple myeloma

Urinary proteins distinct from Bence Jones proteins, but sharing antigenic determinants, were found in the urine of a number of patients with multiple myeloma. These components were smaller in size and antigenically deficient compared with Bence Jones proteins. They were best detected with antiserums to the homologous Bence Jones proteins and, in some cases, were related to the variable portion of the Bence Jones protein molecule.     

Phosphorylation of proteins by inositol pyrophosphates

The inositol pyrophosphates IP7 and IP8 contain highly energetic pyrophosphate bonds. Although implicated in various biologic functions, their molecular sites of action have not been clarified. Using radiolabeled IP7, we detected phosphorylation of multiple eukaryotic proteins. We also observed phosphorylation of endogenous proteins by endogenous IP7 in yeast. Phosphorylation by IP7 is nonenzymatic and may represent a novel intracellular signaling mechanism.     

Inducible nitric oxide synthase binds, S-nitrosylates, and activates cyclooxygenase-2

Cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) are two major inflammatory mediators. Here we show that iNOS specifically binds to COX-2 and S-nitrosylates it, enhancing COX-2 catalytic activity. Selectively disrupting iNOS-COX-2 binding prevented NO-mediated activation of COX-2. This synergistic molecular interaction between two inflammatory systems may inform the development of anti-inflammatory drugs.     

Yield related interpretations of irrigation uniformity and efficiency measures

Summary A number of irrigation performance parameters have been used to quantify irrigation uniformity and efficiency. These parameters are usually regarded as performance indices only, without a physically significant interpretation. Common irrigation uniformity and efficiency measures can be related to expected yields from non-uniform irrigation of certain hypothetical crops. Calculation of these measures is equivalent to, or closely related to, calculation of expected yields with non-uniform irrigation for the water-yield functions of Fig. 1. This relationship between performance measures and expected yield lends physical significance to irrigation uniformity measures, and suggests useful generalizations of traditional uniformity and efficiency measures that are directly related to crop yield.Contribution from the U.S. Salinity Laboratory, USDA-ARS, Riverside, CA 92501     

The global terrestrial carbon cycle

There is great uncertainty with regard to the future role of the terrestrial biosphere in the global carbon cycle. The uncertainty arises from both an inadequate understanding of current pools and fluxes as well as the potential effects of rising atmospheric concentrations of CO₂ on natural ecosystems. Despite these limitations, a number of studies have estimated current and future patterns of terrestrial carbon storage. Future estimates focus on the effects of a climate change associated with a doubled atmospheric concentration of CO₂. Available models for examining the dynamics of terrestrial carbon storage and the potential role of forest management and landuse practices on carbon conservation and sequestration are discussed.