Air pollution as a possible cause for the decline of some phanerogamic species in The Netherlands

In The Netherlands the decline of some phanerogamic species cannot be readily explained from obvious factors such as lowering of the groundwater table, eutrophication or land reclamation. For a number of species the hypothesis was tested that the decline is partly due to air pollution. A two-factor model was made in which decline is accounted for by (a) habitat destruction assessed from topographic maps and (b) air pollution measured as the SO₂ 95-percentile over the winter period 1978/1979. Effects of both factors were assumed to follow a sigmoid dose-effect curve. For a number of species decline proved to be significantly correlated with air pollution. These are notably species from the syntaxon Violion caninae. A comparison was made with results obtained for epiphytic lichens. It appears that for some phanerogamic species sensitivity is about the same as for moderately sensitive lichens.Nomenclature follows Heukels & van der Meijden (1983).Thanks are due to the Rijksherbarium, for providing some of their unpublished data; and to Ada Groeneveld, for technical assistance.     

The CR1 and CR3 domains of the adenovirus type 5 E1A proteins can independently mediate activation of ATF-2.

The adenovirus 12S E1A protein can stimulate the activity of the c-jun promoter through a conserved region 1 (CR1)-dependent mechanism. The effect is mediated by two AP-1/ATF-like elements, jun1 and jun2, that preferentially bind c-Jun-ATF-2 heterodimers. In this study, we show that the ATF-2 component of the c-Jun-ATF-2 heterodimer is the primary target for 12S E1A: 12S E1A can enhance the transactivating activity of the N terminus of ATF-2 when fused to a heterologous DNA-binding domain, whereas the transactivating activity of the c-Jun N terminus is not significantly affected. Activation of the ATF-2 N terminus by 12S E1A is dependent on CR1. In the context of the 13S E1A protein, CR1 and CR3 can both contribute to activation of ATF-2, and their relative contributions are dependent on the cell type. In contrast to activation of ATF-2 by stress-inducing agents, CR1-dependent activation of ATF-2 was found not to depend strictly on the presence of threonines 69 and 71 in the N terminus of ATF-2, which are targets for phosphorylation by stress-activated protein kinases (SAPKs). In agreement with this observation, we did not observe phosphorylation of threonines 69 and 71 or constitutively enhanced SAPK activity in E1A- plus E1B-transformed cell lines. These data suggest that CR1-dependent activation of ATF-2 by 12S E1A does not require phosphorylation of threonines 69 and 71 by SAPK.     

Role of glucose signaling in yeast metabolism

In this article, knowledge concerning the relation between uptake of and signaling by glucose in the yeast Saccharomyces cerevisiae is reviewed and compared to the analogous process in prokaryotes. It is concluded that (much) more fundamental knowledge concerning these processes is required before rational redesign of metabolic fluxes from glucose in yeast can be achieved. (c) 1996 John Wiley & Sons, Inc.     

Quantification of the regulation of glycerol and maltose metabolism by IIAGlc of the phosphoenolpyruvate-dependent glucose phosphotransferase system in Salmonella typhimurium.

The amount of IIAGlc, one of the proteins of the phosphoenolpyruvate:glucose phosphotransferase system (PTS), was modulated over a broad range with the help of inducible expression plasmids in Salmonella typhimurium. The in vivo effects of different levels of IIAGlc on glycerol and maltose metabolism were studied. The inhibition of glycerol uptake, by the addition of a PTS sugar, was sigmoidally related to the amount of IIAGlc. For complete inhibition of glycerol uptake, a minimal ratio of about 3.6 mol of IIAGlc to 1 mol of glycerol kinase (tetramer) was required. Varying the level of IIAGlc (from 0 to 1,000% of the wild-type level) did not affect the growth rate on glycerol, the rate of glycerol uptake, or the synthesis of glycerol kinase. In contrast, the growth rate on maltose, the rate of maltose uptake, and the synthesis of the maltose-binding protein increased two- to fivefold with increasing levels of IIAGlc. In the presence of cyclic AMP, the maximal levels were obtained at all IIAGlc concentrations. The synthesis of the MalK protein, the target of IIAGlc, was not affected by varying the levels of IIAGlc. The inhibition of maltose uptake was sigmoidally related to the amount of IIAGlc. For complete inhibition of maltose uptake by a PTS sugar, a ratio of about 18 mol of IIAGlc to 1 mol of MalK protein (taken as a dimer) was required.     

Role of lipoxygenase products in the effects of angiotensin II in the isolated aorta and perfused heart of the rat

The objective of this study was to determine whether arachidonate metabolites are involved in the vasoconstrictive effects of angiotensin II in rats. In the isolated perfused heart, dexamethasone (4 mg/kg) significantly suppressed the maximal decreases in coronary flow induced by angiotensin II and vasopressin (reference drug). In the heart, the nonselective lipoxygenase inhibitor nordihydroguaiaretic acid (NDGA, 1 muM) markedly suppressed the angiotensin II-induced decreases in coronary flow. NDGA (10 muM) inhibited both angiotensin II- and methoxamine- (reference drug) induced contractions in aortic rings with (in the presence of L-NAME) and without endothelium. In the heart, the leukotriene synthesis inhibitor MK-886 (0.3 muM) significantly reduced the maximal effects to angiotensin II, but the leukotriene antagonist FPL 55712 (0.1 and 0.3 muM) had no effect. We conclude that in the isolated perfused rat heart angiotensin II-induced decreases in coronary flow are in part mediated by Hpoxygenase products, which might be derived from the 5-Hpoxygenase pathway, but are probably not leukotrienes. Furthermore, endothelium independent Hpoxygenase products mediate part of the contractile responses to angiotensin II in the isolated rat aorta.     

Proton movements coupled to sugar transport via the galactose transport system in Salmonella typhimurium.

We have studied proton movements associated with substrate transport via the galactose transport system in Salmonella typhimurium. The addition of galactose to lightly buffered suspensions of anaerobic, non-metabolizing cells of Salmonella typhimurium, specifically induced for the galactose transport system, causes an increase in extracellularpH as galactose and protons enter the cell together. Other substrates for this transport system, D-fucose, 2-deoxygalactose, glucose and 2-deoxyglucose similarly cause an influx of protons when transported. In contrast, transport via the other major transport system for galactose, the methylgalactoside transport system, is not coupled to H+ influx. Comparison of kinetic data obtained from pH measurements with data obtained from measurement of active transport of galactose via the galactose transport system suggests that the apparent Km of the galactose transport system for this sugar differs under energized and non-energized conditions. At pH 7.2 the permeant anion SCN- increases both the rate and extent of galactose-induced proton influx; at pH 6 the rate, but not the extent is increased by SCN-.     

Alkaloids of Papaver bracteatum: 14-β-hydroxycodeinone, 14-β-hydroxycodeine and N-methylcorydaldine

Three new alkaloids have been identified from Papaver bracteatum, 14-β-hydroxycodeinone, 14-β-hydroxycodeine and N-methylcorydaldine. The presence of alpinigenine was also confirmed.     

Avian alcohol dehydrogenase. Characterization of the quail enzyme, functional interpretations, and relationships to the different classes of mammalian alcohol dehydrogenase

The primary structure of the major quail liver alcohol dehydrogenase was determined. It is a long-chain, zinc-containing alcohol dehydrogenase of the type occurring also in mammals and hence allows judgement of the gene duplications giving rise to the classes of the human alcohol dehydrogenase system. The avian form is most closely related to the class I mammalian enzyme (72-75% residue identity), least related to class II (60% identity), and intermediately related to class III (64-65% identity). This pattern distinguishes the mammalian enzyme classes and separates classes I and II in particular. In addition to the generally larger similarities with class I, the avian enzyme exhibits certain residue patterns otherwise typical of the other classes, including an extra Trp residue, present in both class II and III but not in class I, with a corresponding increase in the UV absorbance. The avian enzyme further shows that a Gly residue at position 260 previously considered strictly conserved in alcohol dehydrogenases can be exchanged with Lys. However, zinc-binding residues, coenzyme-binding residues, and to a large extent substrate-binding residues are unchanged in the avian enzyme, suggesting its functional properties to be related to those of the class I mammalian alcohol dehydrogenases. In contrast, the areas of subunit interactions in the dimers differ substantially. These results show that (a) the vertebrate enzyme classes are of distant origin, (b) the submammalian enzyme exhibits partly mixed properties in relation to the classes, and (c) the three mammalian enzyme classes are not as equidistantly related as initially apparent but suggest origins from two sublevels.