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.     

Soluble minerals in chemical evolution

The adsorption of 5-AMP and 5-CMP was studied in saturated solutions of several soluble mineral salts (NaCl, Na₂SO₄, MgCl₂·6H₂O, MgSO₄·7H₂O, CaCl₂·2H₂O, CaSO₄·2H₂O, SrCl₂·6H₂O, SrSO₄, and ZnSO₄·7H₂O) as a function of pH, ionic strength, and surface area of the solid salt. The adsorption shows a pH dependence; this can be correlated with the charge on the nucleotide molecule which is determined by the state of protonation of the N-1 nitrogen of 5-AMP or N-3 nitrogen of 5-CMP and the phosphate oxygens. The adsorption which results from the binding between the nucleotide molecule and the salt surface is proposed as being due to electrostatic forces. It was concluded that the adsorption was reversible in nature. The adsorption shows a strong dependence upon ionic strength and decreases with increasing ionic strength. Surface area is shown to be an important factor in evaluating and comparing the magnitude of adsorption of nucleotides onto various mineral salts. The implications of the results of the study are discussed in terms of the importance of soluble mineral salts as adsorption sites in the characterization of the adsorption reactions of an adsorbed template in biogeochemical cycles.     

Carboxylmethylation of Calmodulin in Cultured Pituitary Cells

We have used fast protein liquid chromatography (FPLC) and reverse-phase HPLC to rapidly resolve carboxylmethylated proteins in cultured pituitary GH3 cells. This procedure preserves labile carboxylmethyl esters, which are lost under the usual procedures employed for protein fractionation. GH3 cells were incubated with [methyl-3H]-methionine in culture and incorporation of label into the soluble fraction, total cell protein, and protein carboxylmethyl esters was determined; protein carboxylmethyl ester formation was shown to be resistant to cycloheximide. Fractionation of protein carboxylmethyl esters from GH3 cells by gel permeation FPLC, anion-exchange FPLC, and reverse-phase HPLC in the presence of calcium and in the presence of EGTA identified two proteins that are major substrates for protein carboxylmethyltransferase and indicated that one of these proteins is calmodulin. Similar results were obtained when a cytosolic fraction from GH3 cells was incubated with S-adenosyl-L-[methyl-3H]methionine. These results indicate that rapid chromatography at low temperature and low pH is useful for the analysis of eucaryotic carboxylmethylated proteins and that contrary to reports obtained in other systems, calmodulin is carboxylmethylated in intact pituitary cells.     

Optimizing the expression of chimeric genes in plant cells

Summary The Serratia marcescens chiA gene encodes a secreted chitinase activity which contributes to the fungal growth inhibition exhibited by this bacterium. The coding region from the chiA gene was fused to the promoter and 3 polyadenylation region of the Agrobacterium nopaline synthase gene. Site-directed mutagenesis of specific nucleotides surrounding the initiating AUG of the coding sequence of this chimeric gene resulted in up to an eight-fold increase in the amount of chitinase protein detected in transformed plant tissue. Analysis of the chiA mRNA indicated that these nucleotides also affected mRNA levels. At least 50% of the chitinase protein produced in transformed tobacco cells was the same molecular weight as the S. marcescen secreted protein.     

Chemical modification of human alpha 1-proteinase inhibitor by tetranitromethane. Structure-function relationship.

Nitration of tyrosine residues of alpha 1-proteinase inhibitor (alpha 1-PI) by tetranitromethane yielded a product that maintained its inhibitory activity against trypsin but lost most of its inhibitory activity against elastase. Chemical analysis of the product showed that four out of the six tyrosine residues in alpha 1-PI had been nitrated to various degrees: Tyr-38 and Tyr-297 were not nitrated, whereas Tyr-138, Tyr-160, Tyr-187 and Tyr-244 were nitrated to extents in the range 40-80%. We interpreted these data to mean that modification of these tyrosine residues decreased the association constant between alpha 1-PI and the proteinases and that the decrease differs from one proteinase to the other. When either alpha 1-PI-trypsin or alpha 1-PI-elastase complex was nitrated, nitration took place only to a very slight extent at these latter four tyrosine residues. On the other hand, Tyr-38 and Tyr-297 underwent nitration to about 20%. We concluded that Tyr-138, Tyr-160, Tyr-187 and Tyr-244 were located on the surface of alpha 1-PI that interacts with either trypsin or elastase in the formation of complexes, and were therefore protected from nitration.     

Acute inflammation in gram-negative infection: endotoxin, interleukin 1, tumor necrosis factor, and neutrophils

Experimental bacterial infection of the dermis induced with gram-negative microorganisms is associated with an acute inflammatory reaction, which represents the principal local defense against spread of the infection. When the inflammatory reaction is quantitated with radiolabeled cells and proteins, the kinetics resemble acute inflammation induced with other agents, such as immune complexes or chemotaxins. There is an interrelationship between the components or events of the inflammatory reaction; inasmuch as vascular injury is neutrophil-dependent, neutrophils must migrate to the site where the bacteria multiply. In neutropenic animals there is no such emigration and bacterial multiplication is not inhibited. The microorganisms shed endotoxin, which in turn induces secretion of interleukin 1 (IL 1) and probably tumor necrosis factor. Endotoxin is the most potent agent (10(-15) mol vs. 10(-12) mol of C5ades Arg) capable of inducing a neutrophil influx. Desensitization or tachyphylaxis of the tissues (probably of postcapillary venular endothelium) to IL 1 seems to control cessation of the neutrophil influx (also in vitro evidence). Phagocytosis of the bacteria by neutrophils is associated with release of oxygen radicals and lysosomal proteases from the neutrophils. These are instrumental in eliciting microvascular injury, which is characterized by enhanced vasopermeability, hemorrhage, and thrombosis.     

The primary structure of rat ribosomal protein L7. The presence near the amino terminus of L7 of five tandem repeats of a sequence of 12 amino acids

The covalent structure of rat ribosomal protein L7 was determined in part from the sequence of nucleotides in a recombinant cDNA and in part from the sequence of amino acids in portions of the protein. The complementary analyses supplemented and confirmed each other. Ribosomal protein L7 contains 258 amino acids and has a molecular weight of 30,040. The protein has an unusual and striking structural feature near the NH2 terminus: five tandem repeats of a sequence of 12 residues. Rat L7 appears to be related to ribosomal protein L7 from the moderate halophile Vibrio costicola and perhaps to L30 from Bacillus stearothermophilus, to L7 from the moderate halophile NRCC 41227, and to L22 from Nicotinia tobaccum chloroplast. In addition, there is a sequence of 24 amino acids in rat protein L7 that may be related to segments of the same number of residues in Escherichia coli ribosomal proteins S10, S15, L9, and L22.