Effects of dietary supplements on space radiation-induced oxidative stress in Sprague-Dawley rats

Of particular concern for the health of astronauts during space travel is radiation from protons and high-mass, high-atomic-number (Z), and high-energy particles (HZE particles). Space radiation is known to induce oxidative stress in astronauts after extended space flight. In the present study, the total antioxidant status was used as a biomarker to evaluate oxidative stress induced by gamma rays, protons and HZE-particle radiation. The results demonstrate that the plasma level of total antioxidants in Sprague-Dawley rats was significantly decreased (P < 0.01) in a dose-dependent manner within 4 h after exposure to gamma rays. Exposure to protons and HZE-particle radiation also significantly decreased the serum or plasma level of total antioxidants in the irradiated animals. Diet supplementation with L-selenomethionine alone or a combination of selected antioxidant agents was shown to partially or completely prevent the decrease in the serum or plasma levels of total antioxidants in animals exposed to gamma rays, protons or HZE particles. These findings suggest that exposure to space radiation may compromise the capacity of the host antioxidant defense and that this adverse biological effect can be prevented at least partially by dietary supplementation with L-selenomethionine and antioxidants.     

Structurally distinct recognition motifs in lymphotoxin-beta receptor and CD40 for tumor necrosis factor receptor-associated factor (TRAF)-mediated signaling

Lymphotoxin-beta receptor (LTbetaR) and CD40 are members of the tumor necrosis factor family of signaling receptors that regulate cell survival or death through activation of NF-kappaB. These receptors transmit signals through downstream adaptor proteins called tumor necrosis factor receptor-associated factors (TRAFs). In this study, the crystal structure of a region of the cytoplasmic domain of LTbetaR bound to TRAF3 has revealed an unexpected new recognition motif, 388IPEEGD393, for TRAF3 binding. Although this motif is distinct in sequence and structure from the PVQET motif in CD40 and PIQCT in the regulator TRAF-associated NF-kappaB activator (TANK), recognition is mediated in the same binding crevice on the surface of TRAF3. The results reveal structurally adaptive "hot spots" in the TRAF3-binding crevice that promote molecular interactions driving specific signaling after contact with LTbetaR, CD40, or the downstream regulator TANK.     

DeltaBAFF,an alternate splice isoform that regulates receptor binding and biopresentation of the B cell survival cytokine,BAFF

The tumor necrosis family member BAFF is limiting for the survival of follicular B lymphocytes, but excessive BAFF signaling can lead to autoimmunity, suggesting that its activity must be tightly regulated. We have identified a conserved alternate splice isoform of BAFF, called deltaBAFF, which lacks 57 nt encoding the A-A1 loop and is co-expressed with BAFF in many mouse and human myeloid cells. Mouse deltaBAFF appears on the plasma membrane, but unlike BAFF it is inefficiently released by proteolysis. DeltaBAFF can associate with BAFF in heteromultimers and diminish BAFF bioactivity and release. Thus, alternative splicing of the BAFF gene suppresses BAFF B cell stimulatory function in several ways, and deltaBAFF may promote other functions as well.     

Gramene: development and integration of trait and gene ontologies for rice

Gramene (http://www.gramene.org/) is a comparative genome database for cereal crops and a community resource for rice. We are populating and curating Gramene with annotated rice (Oryza sativa) genomic sequence data and associated biological information including molecular markers, mutants, phenotypes, polymorphisms and Quantitative Trait Loci (QTL). In order to support queries across various data sets as well as across external databases, Gramene will employ three related controlled vocabularies. The specific goal of Gramene is, first to provide a Trait Ontology (TO) that can be used across the cereal crops to facilitate phenotypic comparisons both within and between the genera. Second, a vocabulary for plant anatomy terms, the Plant Ontology (PO) will facilitate the curation of morphological and anatomical feature information with respect to expression, localization of genes and gene products and the affected plant parts in a phenotype. The TO and PO are both in the early stages of development in collaboration with the International Rice Research Institute, TAIR and MaizeDB as part of the Plant Ontology Consortium. Finally, as part of another consortium comprising macromolecular databases from other model organisms, the Gene Ontology Consortium, we are annotating the confirmed and predicted protein entries from rice using both electronic and manual curation.     

Defining a pathway of communication from the C-terminal peptide binding domain to the N-terminal ATPase domain in a AAA protein

AAA proteins remodel other proteins to affect a multitude of biological processes. Their power to remodel substrates must lie in their capacity to couple substrate binding to conformational changes via cycles of nucleotide binding and hydrolysis, but these relationships have not yet been deciphered for any member. We report that when one AAA protein, Hsp104, engages polypeptide at the C-terminal peptide-binding region, the ATPase cycle of the C-terminal nucleotide-binding domain (NBD2) drives a conformational change in the middle region. This, in turn, drives ATP hydrolysis in the N-terminal ATPase domain (NBD1). This interdomain communication pathway can be blocked by mutation in the middle region or bypassed by antibodies that bind there, demonstrating the crucial role this region plays in transducing signals from one end of the molecule to the other.     

Genome-wide detection of LOH in prostate cancer using human SNP microarray technology

Loss of heterozygosity (LOH) of chromosomal regions is crucial in tumor progression. In this study we assessed the potential of the Affymetrix GeneChip HuSNP mapping assay for detecting genome-wide LOH in prostate tumors. We analyzed two human prostate cell lines, P69SV40Tag (P69) and its tumorigenic subline, M12, and 11 prostate cancer cases. The M12 cells showed LOH in chromosomes 3p12.1-p22.1, 11q22.1-q24.2, 19p13.12, and 19q13.42. All of the prostate cases with informative single-nucleotide polymorphism (SNP) markers showed LOH in 1p31.2, 10q11.21, 12p13.1, 16q23.1-q23.2, 17p13.3, 17q21.31, and 21q21.2. Additionally, a high percentage of cases showed LOH at 6p25.1-p25.3 (75%), 8p22-p23.2, and 10q22.1 (70%). Several tumor suppressor genes (TSGs) have been mapped in these loci. These results demonstrate that the HuSNP mapping assay can serve as an alternative to comparative genomic hybridization for assessing genome-wide LOH and can identify chromosomal regions harboring candidate TSGs implicated in prostate cancer.     

Evaluation of an alternative IMS dissociation procedure for use with Method 1622: detection of Cryptosporidium in water

U.S. EPA Methods 1622 and 1623 are used to detect and quantify Cryptosporidium oocysts in water. The protocol consists of filtration, immunomagnetic separation (IMS), staining with a fluorescent antibody, and microscopic analysis. Microscopic analysis includes detection by fluorescent antibody and confirmation by the demonstration of 1-4 sporozoites or nuclei after staining with 4',6-diamidino-2-phenyl indole dihydrochloride (DAPI). The purpose of this study was to evaluate a new IMS dissociation, a 10-min incubation at 80 degrees C. Heat dissociation improved the average oocyst recovery from 41% to 71% in seeded reagent water, and from 10% to 51% in seeded river samples. The average DAPI confirmation rate improved from 49% to 93% in reagent water, and from 48% to 73% in river samples. This modification improved both oocyst recovery and confirmation.     

Discrete signaling regions in the lymphotoxin-beta receptor for tumor necrosis factor receptor-associated factor binding, subcellular localization, and activation of cell death and NF-kappaB pathways

Lymphotoxin-beta receptor (LTbetaR), a member of the tumor necrosis factor receptor superfamily, is essential for the development and organization of secondary lymphoid tissue. Wild type and mutant LTbetaR containing successive truncations of the cytoplasmic domain were investigated by retrovirus-mediated gene transfer into HT29.14s and in 293T cells by transfection. Wild type receptors accumulated in perinuclear compartments and enhanced responsiveness to ligand-induced cell death and ligand-independent activation of NFkappaB p50 dimers. Coimmunoprecipitation and confocal microscopy mapped the TRAF3 binding site to amino acids PEEGDPG at position 389. However, LTbetaR truncated at position Pro(379) acted as a dominant positive mutant that down-modulated surface expression and recruited TRAF3 to endogenous LTbetaR. This mutant exhibited ligand-independent cell death and activated NF-kappaB p50 dimers. By contrast, truncation at Gly(359) created a dominant-negative mutant that inhibited ligand-induced cell death and activation of NF-kappaB p50/p65 heterodimers. This mutant also blocked accumulation of wild type receptor into perinuclear compartments, suggesting subcellular localization may be crucial for signal transduction. A cryptic TRAF-independent NF-kappaB activating region was identified. These mutants define discrete subregions of a novel proline-rich domain that is required for subcellular localization and signal transduction by the LTbetaR.