Enzyme activities in a clay-loam soil amended with various crop residues

Summary Amylase, dehydrogenase, arylsulphatase and phosphatases activities were measured in a clay-loam soil amended with seven different crop residues. All enzyme activities, except phosphomonoesterase, were generally higher in the derived soil samples than in the original soil. Addition of tobacco and sunflower residues caused an increase on most of the enzyme activities while tomato residues increased only the amylase and phosphodiesterase activities. As the enzyme activities were positively correlated to each other, a common source of the enzymes is suggested even though the coefficients of correlation demonstrate that only a low percentage of the variability can be ascribed to the interactions among enzyme activities.     

Decomposition of three halophytes in different habitats of an eastern scheldt salt marsh

Summary A 20.5-month study was undertaken to determine detrital processing of the halophytesSpartina anglica, Elytrigia pungens, andHalimione portulacoides in three different habitats of an estuarine salt marsh in the South-West Netherlands. Decomposition was measured using litter-bags of three different mesh sizes to partition the effects of different faunal groups on decomposition. From April 1980 through October 1981 litter-bags were sampled regulary from a creek, the upper marsh, and from a plant-debris belt on the higher marsh. Dry weights and nutritive values were measured and animals were counted. Mainly rates of loss are reported here. Zonal differences were significant. At first, decomposition in the creek was most rapid. After two months the processes in the creek slowed down because of the trapping of silt by the bags, which probably simulated the natural course of the decomposition process in the water. Decomposition on the marsh followed the most regular pattern, while in the plant-debris belt the pattern was very irregular. Population dynamics of microfaunal organisms supported these findings. In the plant-debris belts loss rates seem to be higher than on the marsh, because of the influence of detritivorous macrofaunal organisms. The loss rates of the three plant species differed significantly.Halimione decomposed fastest, especially in the beginning, and in the plant-debris habitat. On the upper marsh and in the plant-debris belt the loss rates ofSpartina seem to be a little higher than those ofElytrigia.Communication No. 233, Delta Institute for Hydrobiological Research, Yerseke, The Netherlands.     

Drought resistance in pearl millet

The influence of wilting on the levels of free proline, soluble proteins, reducing sugars, starch and on the activities of nitrate reductase, invertase, amylase and pyrophosphatases have been studied in the leaf tissue of five cultivars of pearl millet at their vegetative stage under pot culture conditions. The metabolic changes could not be correlated with the yield behaviour of the cultivars under a drought condition in the field.     

Regulation of the L-arabinose transport operons in Escherichia coli

l-Arabinose is transported into Escherichia coli via two independent transport systems, a system possessing relatively low affinity for arabinose, the araE system, and a system of higher affinity for arabinose, the araFG system. In the work reported here we demonstrate that insertion of the Mu-lac bacteriophage isolated by Casadaban &; Cohen (1979) permits a reliable measurement of the expression of these two operons. Using appropriate Mu-lac insertion strains we found that both of the arabinose transport operons can be induced approximately 150-fold by the presence of arabinose, and that induction of both transport operons requires CRP (cyclic AMP receptor protein), but that their catabolite sensitivities differ from one another. In addition, we show that the araC⁺ allele is dominant to the C^c allele in the control of the transport operons, just as is found in the araBAD operon.     

Phosphorylation of liver pyruvate kinase by Ca++/calmodulin-dependent protein kinase: characterization of two phosphorylation sites

Rat liver pyruvate kinase is phosphorylated by calcium/calmodulin-dependent protein kinase II at serine and threonine residues in a 3-4 kDa CNBr fragment located near the amino terminus. The two sites of phosphorylation were separated by reverse-phase HPLC of a thermolysin digest. Sequence analysis established the sites of phosphorylation as follows: Leu-Arg-Arg-Ala-Ser(PO4)-Val-Ala-Gln-Leu-Thr(PO4)-Gln-Glu.     

The scale-up from 0.1 to 100 liter of a unit process system based on 3-mm-diameter glass spheres for the production of four strains of FMDV from BHK monolayer cells

This paper describes the scale-up from 0.1 to 100 liter of the unit process based on 3-mm-diameter glass spheres for the growth of BHK monolayer cells. The production of four strains of FMD virus at the 0.1-, 10-, and 100-liter scales was examined. Cell growth was estimated from measurements of the concentration of glucose in the growth medium, while the release of virus was inferred from measuring the concentration of LDH in the culture supernatant fluid. The yields of virus at 0.1-, 1-, and 10-liter scales were similar but that from the 100-liter version was somewhat lower. The reason for this lower yield and the method used to overcome it over outlined.     

Tissue producing the serum factor stimulating the release of cathepsin D from lysosomes in vitro

Pancreatectomy as well as thyroparathyroidectomy resulted in the quick disappearance of a serum factor (stimulating cathepsin D release from lysosomes in vitro) from the rat or mouse blood. Extirpation of other organs such as duodenum, stomach, spleen, kidney, submaxillary gland, testis, adrenal gland or hypophysis, showed no effect on the serum factor level. Glucagon (but not insulin or thyroxine) given to the pancreatectomized animals restored the serum factor level in a dose-dependent manner. The serum factor-like activity was detected only in the parathyroids (but not thyroid), and the release of activity from parathyroid-slices was stimulated by glucagon, suggesting that the parathyroid may produce and/or secrete the serum factor under the influence of glucagon.     

Possible incorporation of phosphoserine into globin readthrough protein via bovine opal suppressor phosphoseryl-tRNA

Suppressor [32P]phosphoseryl-tRNA, prepared using bovine seryl-tRNA synthetase and ATP:seryl-tRNA phosphotransferase, was mixed with rabbit reticulocyte lysates containing endogenous hemoglobin mRNA having the termination codon UGA (opal). The chromatographic pattern of the lysate on Sephacryl S-200 showed that the radioactivity of [32P]phosphate in the hot trichloroacetic acid-precipitate (phosphoprotein) was eluted at the position between mature hemoglobin and globin subunits. The phosphoprotein, obtained by chromatography on S-200, moved to the position corresponding to that of globin readthrough protein on SDS-PAGE. The analyses of the hydrolyzate of the phosphoprotein showed the presence of phosphoserine in the protein. These results suggest that animal opal suppressor tRNA functions in vitro to transfer phosphoserine to the position of the termination codon UGA (opal) on mRNA.