Transgenic HLA-DR alpha faithfully reconstitutes IE-controlled immune functions and induces cross-tolerance to E alpha in E alpha 0 mutant mice

We have constructed transgenic mice that express the human class II MHC molecule HLA-DR alpha on a genetic background in which the equivalent endogenous gene, H-2 IE alpha, is not expressed. In these mice, DR alpha complemented the E beta chain such that tissue-specific expression of an interspecies hybrid DR alpha-E beta heterodimer was obtained. Despite 25% amino acid differences between DR alpha and E alpha, immune responsiveness to IE-controlled antigens, clonal deletion of IE-reactive T cells, and alloantigenicity were quantitatively and qualitatively indistinguishable in IE-positive mice and in mice that had integrated at least four copies of the transgene. These results demonstrate a remarkable degree of structural, regulatory, and functional conservation. They also suggest that tolerance induction involves only discrete portions of MHC molecules.     

Radiolysis of DNA in aqueous solution in the presence of a scavenger: A kinetic model based on a nonhomogeneous reaction of OH radicals with DNA molecules of spherical or cylindrical shape

Summary Two expressions are given for the survival dose of DNA exposed to high-energy radiation in aqueous solution in the presence of a scavenger. They are derived from a model where a diffusion controlled reaction of OH radicals occurs on the surface of the DNA macromolecules in competition with scavenging in the bulk of the solution. The DNA molecules are approximated either by spheres or by cylinders. The model based on molecules of spherical shape corresponds closely to that developed by van Rijn et al. [20]. Expressions obtained from the cylindrical model are used to account for the dependence on the scavenger concentration of some experimentally measured quantities, namely the survival dose and theG value for single-strand breaks upon Co -irradiation ofX 174 DNA and polyadenylic acid, respectively.In memoriam Prof. Dr. O.E. Polansky     

Developmental expression of 44-kDa bone phosphoprotein (osteopontin) and bone γ-carboxyglutamic acid (Gla)-containing protein (osteocalcin) in calcifying tissues of rat

New aspects of the distribution and developmental appearance of the 44-kDa bone phosphoprotein (44K BPP, also called sialoprotein I or osteopontin) and bone gamma-carboxyglutamic acid (Gla)-containing protein (BGP, also called osteocalcin) during osteogenesis and dentinogenesis were investigated with immunocytochemical techniques using monospecific, affinity-purified polyclonal antibodies. Sections from newborn rat incisors and from various bone anlagen of newborn animals and fetuses were processed for detection of 44K BPP or BGP antigenicity. In addition, histochemical reactions for detection of alkaline phosphatase or calcium salts were performed on a number of the sections. The 44K BPP appears to be synthesized and secreted by chondrocytes only in the areas of cartilage-to-bone transition; these cells could participate indirectly in the process of bone formation by providing a suitable scaffold onto which primary marrow osteoblasts attach and spread. During osteogenesis, 44K BPP is found in bone-forming cells almost concomitantly with the appearance of alkaline phosphatase and before osteoid deposition, whereas BGP is still absent during early stages of mineralization. We hypothesize that this dramatic difference between the developmental appearance of 44K BPP and BGP reflects the delayed expression of the BGP gene relative to that of 44K BPP. In long-term cultures of bone marrow from adult mice, some fibroblastic cells expressed the 44K BPP phenotype; these cells could represent early osteogenic progenitor cells. Some experiments also suggested that, as with BGP, 44K BPP or an immunologically related protein is synthesized by some odontoblasts and secreted into predentin, prior to the onset of mineralization.     

The role of transmembrane cationic gradients in immune complex stimulation of human polymorphonuclear leukocytes

The role of monovalent cationic gradients in human polymorphonuclear leukocyte (PMNL) stimulation was investigated by monitoring immune complex-stimulated transmembrane depolarization and superoxide production, events which accompany--and have been used as indicators of --PMNL activation. Abolishing only the Na+ gradient by substitution of choline for extracellular Na+ did not affect the resting membrane potential but reduced the rate of stimulus-induced transmembrane depolarization to 50% of control. In contrast, collapsing both Na+ and K+ gradients by suspension in K+ buffer (high K-PRK) depolarized the cells and reduced the stimulus-induced rate of depolarization to 11% of control. Pretreatment of cells suspended in Na+ buffers with 5-(N,N-dimethyl)amiloride hydrochloride (DMA) or with valinomycin reduced by one-half the rate of immune complex induced membrane depolarization. Conversely, in the absence of either or of both Na+ or K+ gradients, or in the presence of valinomycin, immune complex elicited an enhanced rate of superoxide production. However, PMNL prepared via NH4Cl (NH4Cl-PMNL) instead of H2O (H2O-PMNL) lysis of residual red blood cells exhibited an absolute requirement for an intact Na+ gradient in cell stimulation. The present results thus demonstrate that: 1) both Na+ and K+ gradients participate equally in the membrane depolarization elicited by immune complex; 2) neither a Na+ or a K+ gradient is required for immune complex activation, or for activity of the respiratory burst; and 3) an artifactual requirement for an intact Na+ gradient occurs in neutrophils prepared by the NH4Cl lysis technique.     

Indomethacin, but not dazoxiben, reduced lung fluid filtration after E. coli infusion

Goats were divided into three groups and given infusions of live Escherichia coli bacteria. Group I received no treatment, group II was treated with indomethacin (a cyclooxygenase inhibitor), and group III with dazoxiben (a thromboxane synthase inhibitor). Double indicator-dilution extravascular lung water (EVLW) in group I was significantly different from the treated groups. There was an early increase in EVLW in group I and group III but not in group II animals. At 6 h EVLW's in group I, group II, and group III were 100, 45, and 30% above base line, respectively. Lymph flow (QL) and lymph-to-plasma protein ratio (L/P) was not statistically different between groups. Estimated total fluid filtration [QL + d(EVLW)/dt] in group I and III was markedly elevated between 0 and 1.5-2 h after E. coli infusion. Cardiac output (QT) decreased to 40% of base line in group I, and it decreased slightly in group II because of the indomethacin but did not decrease after E. coli. QT decreased in group III but recovered more rapidly than group I. Mean pulmonary arterial pressure increased more rapidly in group I and reached a higher peak than either treated group. At 6 h these groups had similar pulmonary arterial and pulmonary arterial wedge pressures. We conclude that 1) indomethacin but not dazoxiben blocks the early increase in total fluid filtration after bacterial infusion, 2) dazoxiben does not prevent the increased endothelial permeability resulting from infusion of live bacteria, and 3) indomethacin may somewhat ameliorate the endothelial permeability change.(ABSTRACT TRUNCATED AT 250 WORDS)     

Glyphosate tolerant flax plants from Agrobacterium mediated gene transfer

Agrobacterium tumefaciens carrying a disarmed Ti-plasmid vector containing a chimeric NPT-II gene and a glyphosate resistance plant-derived 5-enolpyruvylshikimate-3-phosphate synthase gene was used to transform flax hypocotyl tissues. Transformed shoots could be regenerated from the inoculated tissue and were proven to be transgenic by the combination of leaf callus assays, nopaline assays and progeny tests. Co-segregation was observed in the progeny for kanamycin and glyphosate resistance.     

Paleobiology of a Neoproterozoic tidal flat/lagoonal complex: the Draken Conglomerate Formation, Spitsbergen

Carbonates and rare shales of the ca 700-800 Ma old Draken Conglomerate Formation, northeastern Spitsbergen, preserve a record of environmental variation within a Neoproterozoic tidal flat/lagoon complex. Forty-two microfossil taxa have been recognized in Draken rocks, and of these, 39 can be characterized in terms of their paleoenvironmental distributions along a gradient from the supratidal zone to permanently submerged lagoons. Supratidal to subtidal trends include: increasing microbenthic diversity, increasing abundance and diversity of included allochthonous (presumably planktonic) elements, decreasing sheath thickness of mat-building organisms (with significant taphonomic consequences), and an increasing sediment/fossil ratio in fossiliferous rocks. Five principal and several minor biofacies can be distinguished. The paleoecological resolution obtainable in the Draken Conglomerate Formation rivals that achieved for most Phanerozoic fossil deposits. It documents the complexity and diversity of Proterozoic coastal ecosystems and indicates that both environment and taphonomy need to be taken into explicit consideration in attempts to understand evolutionary trends in early fossil record. Three species, Coniunctiophycus majorinum, Myxococcoides distola, and M. chlorelloidea, are described as new; Siphonophycus robustum, Siphonophycus septatum, and Gorgonisphaeridium maximum are proposed as new combinations.     

Influence of mefluidide on growth,development, and cell wall digestibility of sorghum

Application of mefluidide (N-[2,4-dimethyl-5-([(trifluoromethyl)sulfonyl]amino) phenyl]acetamide) inhibits plant development in perennial grasses. This study examined the effect of mefluidide on the morphological development and digestibility of sorghum. In the greenhouse, 5.9 × 10^–5 g active ingredient (a.i.) plant^–1 applied at the seedling, eight-leaf and boot stages reduced mean plant height 70%, 59%, and 2%, respectively. Heights were also reduced 14%, 15% and 35% by 5.9 × 10^–8, 5.9 × 10^–7 and 5.9 × 10^–6 gram a.i. plant^–1 applied at the eight-leaf stage. Field application of 0.26 or 0.52 kg ha^–1 mefluidide at either the eight-leaf or flagleaf stage reduced mean plant height of all cultivars. Basal tiller numbers increased 319% 28 d, and dry matter production was reduced 65% 42 d following mefluidide application at the eight-leaf stage. Treated stems were 34% higher and treated leaves were 7% higher in cellulase dry matter digestibility than control plants following mefluidide application at the eight-leaf stage. These results indicate that mefluidide application to vegetative stages in sorghum may enhance the forage value of the plants while it inhibits normal plant growth.