Adenosine-5′-d: rotational conformation of the 5′-carbinol group

A synthesis of adenosine-5′-d (4), and its p.m.r. spectral characteristics, are described. The presence of deuterium in 4 gives rise to a 2:1 mixture of R and S configurations at C-5, thereby permitting specific assignments for the resonances of the residual 5′-protons. From the observed spin-spin coupling between the latter and H-4′, and estimate has been made of the rotamer population of the exocyclic 5′-carbinol group. It is shown that the gauche-gauche rotamer is preponderant (≈70%) and the gauche-trans one of minor importance (≈20%) in aqueous solution, which contrasts markedly with the preference for the latter rotamer exhibited by adenosine in the solid state.     

Expression, regulation, and function of P2X4 purinergic receptor in human cervical epithelial cells

Micromolarconcentrations of ATP stimulate biphasic change in transepithelialconductance across CaSki cultures on filters, an acute transientincrease (phase I response; triggered by P2Y₂ receptor and mediated by calcium mobilization-dependent cell volume decrease) followed by a slower decrease in permeability (phase II response). Phase II response is mediated byaugmented calcium influx and protein kinase C-dependent increase intight junctional resistance. The objective of the study was todetermine the role of P2X₄ receptor as a mediator ofphase II response. Human cervical epithelial cells expressP2X₄ receptor mRNA (1.4-, 2.2-, and 4.4-kb isoforms byNorthern blot analysis) and P2X₄ protein. Depletion ofvitamin A reversibly downregulated P2X₄ receptor mRNA andprotein and ATP-induced calcium influx. Depletion of vitamin Aabrogated phase II response, and the effect could bepartially reversed only with retinoic acid receptor (RAR)-selectiveretinoids but not retinoid X receptor (RXR) agonists. Depletion ofvitamin A also abrogated protein kinase C increase in tight junctionalresistance, and the effect could not be reversed with retinoids.Depletion of vitamin A also abrogated phase I increase inpermeability and reversibly downregulated P2Y₂ receptormRNA and ATP-induced calcium mobilization. However, in contrast tophase II response, both RAR and RXR agonists could fullyreverse those effects. These results suggest that phase IIresponse is mediated by a P2X₄ receptor mechanism.

     

Gene transfection of the HuLy-m2 (Leu-9) antigen into mouse L cells

Human DNA was transfected into mouse L cells and tk⁺ HuLy-m2⁺ (= CD7⁺) transfectants isolated after growth in hypoxanthine, aminopterin, thymidine medium and repeated cloning. After several cycles of transfection, > 90% of HuLy-m2⁺ L cells could be detected, by rosetting and by cytofluorography, which showed the transfectants to have a density of CD7 two to five times that found on peripheral blood lymphocytes. Despite this, the 37 kd CD7⁺ dimer could only be identified with difficulty using cell-surface radioiodination and sodium dodecyl sulfate-polyacrylamide gel electrophoresis techniques. An antiserum was produced (C3H anti-HuLy-m2⁺ L cells) which, after absorption, was shown to react with HuLy-m2 antigens present on human thymocytes and lymphocytes and on CD7⁺ transfected L cells.Abbreviations BSA bovine serum albumin - DME Dulbecco's modified Eagle's medium - EDTA ethylenediamine-tetraacetate - HAT hypoxanthine, aminopterin, thymidine - HSV herpes simplex virus - PBL peripheral blood lymphocyte - PBS phosphate-buffered saline - RFC rosette-forming cell - SDS-PAGE sodium dodecyl sulfate-polyacrylamide gel electrophoresis - tk thymidine kinase     

Big Moose Basin: simulation of response to acidic deposition

The ILWAS model has been enhanced for application to multiple-lake hydrologic basins. This version of the model has been applied to the Big Moose basin, which includes Big Moose Lake and its tributary streams, lakes, and watersheds. The basin, as defined, includes an area of 96 km², with over 20 lakes and ponds, and 70 km of streams. Hydrologic and chemical calibrations have been made using data from seven sampling stations. When total atmospheric sulfur loading to the basin is halved, the model predicts, after four years of simulation, a decreasing sulfate concentration and to a lesser extent a rising alkalinity at Big Moose Lake outlet. At the end of four years, the results show an increase in pH of 0.1 to 0.5 pH units depending upon season.     

Ethylene and wound-induced cyanide-resistant respiration climaxes in potato: The synergistic role of CO2 and the selective role of lycorine

When treated with ethylene in O₂, conditioned potato (Solanum tuberosum L. cv. Russet Burbank) tubers – that is, tubers kept at room temperature for 10 days or more – yield slices that are CN^? resistant. Ten % CO₂ in the gas mixture not only synergizes the effect of ethylene, but replaces the need for conditioning as well. The response to CO₂ is more pronounced with increasing time from harvest. By contrast fresh slices from untreated tubers are CN^? sensitive, as are slices from tubers incubated in O₂ or O₂ plus CO₂. The suggestion is made that CN^? resistance is constitutive, and that treatment with ethylene/CO₂ in O₂ confers on potato tuber tissue a resistance to the extensive degradation of membrane phospholipids that normally attends slicing and leads to the loss of CN^? resistance. In this connection respiration inhibition by imidazole, an inhibitor of fatty acid α-oxidation, is extensive in slices of untreated tubers, and sharply diminished in slices of ethylene-treated tubers in proportion to their CN^? resistance. The coextensive rise of respiration rate and CN^? resistance in aged potato slices has led to the presumption that the CN^?-resistant path mediates the respiration climax. Accordingly the alkaloid, lycorine, has been considered to inhibit the development of CN^? resistance in aging potato slices because it curtails the wound-induced respiration. A comparison was carried out on the effect of lycorine on CN^?-sensitive and CN^?-resistant fresh slices – the latter obtained from ethylene/CO₂-treated tubers. Lycorine suppressed the development of the wound-induced respiration without restricting the development of CN^? resistance.     

Characterization of the chicken oocyte receptor for low and very low density lipoproteins

The chicken oocyte receptor for low and very low density lipoproteins has been identified and characterized. Receptor activity present in octyl-beta-D-glucoside extracts of oocyte membranes was measured by a solid phase filtration assay, and the receptor was visualized by ligand blotting. The protein had an apparent Mr of 95,000 in sodium dodecyl sulfate-polyacrylamide gels under nonreducing conditions and exhibited high affinity for apolipoprotein B-containing lipoproteins, but not for high density lipoproteins or lipoproteins in which lysine residues had been reductively methylated. Binding of lipoproteins was sensitive to EDTA, suramin, and treatment with Pronase. In these aspects, the avian oocyte system was analogous to the mammalian low density lipoprotein receptor in somatic cells. Furthermore, a structural relationship between the mammalian and avian receptors was revealed by immunoblotting: polyclonal antibodies directed against the purified bovine low density lipoprotein receptor reacted selectively with the 95-kDa chicken receptor present in crude oocyte membrane extracts.     

Influence of Nitrogen Fertilizers on Growth, Spore Production and Germination, and Biocontrol Potential of Trichoderma and Gliocladium

The mycelial weight of eight out of nine isolates of Trichoderma spp. and Gliocladium virens increased in media supplemented with 2000 mg/l of nitrogen (N) from the fertilizers NH₄Cl, NaNO₃, and a commercial 20–20–20. In general, the greatest increase in growth (up to 311 %) occurred with 20–20–20. The extent of growth was similar with either NH₄Cl or NaNO₃, but was less than that with 20–20–20. Measured by radial development on agar surfacesgrowth of isolates was either not affected or was constricted by supplemental fertilizers. Production of conidia by six out of eight isolates was stimulated by 20–20–20 but not by NH₄Cl or NaNO₃. Germination of conidia of all isolates, generally was high (> 85 %) on amended and nonamended agar. Chlamydospore formation by three Trichoderma isolates in liquid media was not affected by fertilizers. Antagonism or overgrowth of the pathogen Rhizoctonia solani by Trichoderma isolates in culture was reduced appreciably by NaNO₃, but was not affected by NH₄Cl or 20–20–20. Addition of 20–20–20 to natural soil did not reduce further the survival of R. solani caused by germling preparations of six out of seven Trichoderma isolates. However, reduction in survival of the pathogen caused by a T. hamatum isolate was stimulated further (45 %) by the fertilizer.