Airborne Ns (NO2 and NH3) in the Rijeka Bay area (Croatia), 1980-1995

The determination of ambient levels of nitrogen dioxide (NO2) and ammonia (NH3) in the Rijeka Bay area started in 1980, as a part of the air quality monitoring programme. The results of 15 years of surveying (1980/81-1994/95) on ambient levels of these pollutants at two sampling sites are given in this work. Site 1 is located in the city, opposite the old petroleum refinery facilities, while Site 2 is located in the settlement 25 km from the city, opposite the eastern industrial zone. Annual means of NO2 varied between 34 and 60 g/m3 at Site 1 and between 14 and 26 g/m3 at Site 2, but do not follow the 40% reduction in industrial emissions of this pollutant, probably due to the dominant impact of other minor sources, like traffic. Yearly averages of NH3 were in the range of 13 to 26 g/m 3 at Site 1 and 7 to 16 g/m3 at Site 2, and are practically constant during the period studied.     

Mechanistic studies on metal-pyrophosphate hydrolysis. Structure of tetraammine(chloroaquo)cobalt (III) dichloride ([Co(NH3)4ClH2O]2+.2Cl-), an acid hydrolysis product of Co(NH3)4HP2O7 and Co(NH3)4PO4

The octahedral complex tetraammine(chloroaquo)cobalt(III) dichloride is shown to be the HCl hydrolysis product of both P1,2-bidentate tetraammine(pyrophosphato)cobalt(III) [Co(NH3)4HP2O7 or CoPP] and bidentate tetraammine(phosphato)cobalt(III) [Co(NH3)4PO4 or CoP]. The complex crystallizes in the orthorhombic space group Pna21 with cell dimensions a = 13.033(2)A, b = 6.710(1)A, and c = 10.318(2)A; the crystal structure was refined to a final disagreement index of 0.033. The average of the four Co-N distances is 1.944 +/- 6A. The Co-Cl distance is 2.257(2)A and the Co-O(W) distance is 1.971(4)A. Both protons of the coordinated water molecule are engaged in strong hydrogen bonds to the two nonbonded chloride counterions with O(W)-Cl distances of 3.087(6)A and 3.123(6)A. Each nonbonded chloride is engaged in seven hydrogen bonding interactions resulting from the high ratio of hydrogen bond donors to acceptors in the CoP structure. Cobalt bisphosphate (CoP2) is the final enzyme hydrolysis product when CoPP is used as substrate in the yeast inorganic pyrophosphatase reaction. The bridge oxygen atom is the site of initial CoPP cleavage both for HCl catalyzed hydrolysis as well as for enzyme catalyzed hydrolysis.     

Electrochemical investigations of platinum-methyluracil-blue and the related binuclear complex [(NH3)2Pt(MeU)2Pt(NH3)2](NO3)2

The redox behavior of the head-to-head bis(μ- (1-methyluracilato-N³,O²)-bis(cis-diammine platinum(II)) dinitrate, PtMeU, and platinum 1-methyluracil blue, PtMeUB, was studied by cyclic voltammetry (CV), rotating disk voltammetry (RDV), and controlled-potential coulometry (CPC). Redox titrimetry, electrochemistry/electron paramagnetic resonance spectroscopy (EPR), and liquid chromatography (LC) served as complementary techniques. The former reactant exhibits two-step electro-oxidation, consistent with the formation of a mixed-valence Pt(II, III) state en route to Pt(III, III). The latter also appears to oxidize to a uniform Pt(III) state. Although the oxidative-reductive electrochemistry of both reactants exhibits chemical reversibility, the heterogeneous electron-transfer kinetics are notably sluggish. The latter appears to be associated with the formation of an inhibiting film on the electrode surface. A slow conversion of PtMeU to a PtMeUB-like state was revealed by CV and LC. The complex, oligomeric nature of PtMeUB was revealed by means of gradient LC examination. Comparing oxidative and reductive electrolysis curves for PtMeUB yielded an average platinum oxidation state of 2.08. All observed behavior for PtMeUB, as well as for PtMeU, is accounted for by invoking +2 and +3 oxidation states for platinum; redox titrimetry using Ce(IV) revealed inconsequential oxidation of both of these systems beyond the III state. An estimate of molecular weight for the platinum blue was made by employing RDV in conjunction with the Einstein-Stokes equation.     

Photosynthetic Assimilation of NO(3) by Intact Cells of the Cyanobacterium Anacystis nidulans: Influence of NO(3) and NH(4) Assimilation on CO(2) Fixation

Illuminated suspensions of Anacystis nidulans, supplied with saturating concentrations of CO₂ evolved O₂ at a greater rate when nitrate was simultaneously present. The extent of the stimulation of noncyclic electron flow induced by nitrate was dependent on light intensity, being maximal under light saturating conditions. Accordingly, nitrate depressed the rate of CO₂ fixation at limiting but not at saturating light, this depression reflecting the competition between both processes for assimilatory power. In contrast, ammonium stimulated CO₂ fixation at any light intensity assayed, the stimulation being dependent on the incorporation of ammonium to carbon skeletons. The positive effect of ammonium on CO₂ fixation also appeared to occur when nitrate was the nitrogen source, since with either nitrogen source an increase in the incorporation of newly fixed carbon into acid-soluble metabolites took place. From these results, the in vivo partitioning of assimilatory power between photosynthetic nitrogen and carbon assimilation and the quantitative and qualitative effects of inorganic nitrogen assimilation on CO₂ fixation are discussed.     

Effects of NaCl on Growth, Nitrogen Incorporation and Chemical Composition of Inoculated and NH4NO3 Fertilized Vicia faba (L. ) Plants

Vicia faba cv. Maris Bead was grown either on fixed nitrogenor on ammonium nitrate. After 4 weeks growth, nutrient solutionswere supplemented with 50, 75 and 100 mol m^–3 NaCl for15 d. Five harvests were made at weekly intervals, beginningat 4 weeks. Effects of salinity were directly related to dose,plant growth (fresh and dry weight) being depressed in bothN-fixing and N-fertilized plants. The number of nodules perplant and the proportion of those formed which developed intothe active nitrogen fixing state were depressed by salt stress.Increased size of nodules in salt-stressed plants only partlycompensated for the lower specific nitrogenase activity. Theeffects of salinity on plant nitrogen content were more pronouncedon N-flxing than on N-fertilized plants. The former took upmore Na⁺ and Cl^– than the latter: the implications ofthis and of ionic imbalance are discussed. Key words: Vicia faba, Growth, Salt stress, Nodulation     

Uptake and Assimilation of NO(3) and NH(4) by Nitrogen-Deficient Perennial Ryegrass Turf

Assimilation of NO₃⁻ and NH₄⁺ by perennial ryegrass (Lolium perenne L.) turf, previously deprived of N for 7 days, was examined. Nitrogen uptake rate was increased up to four- to five-fold for both forms of N by N-deprivation as compared to N-sufficient controls, with the deficiency-enhanced N absorption persisting through a 48 hour uptake period. Nitrate, but not NH₄⁺, accumulated in the roots and to a lesser degree in shoots. By 48 hours, 53% of the absorbed NO₃⁻ had been reduced, whereas 97% of the NH₄⁺ had been assimilated. During the early stages (0 to 8 hours) of NO₃⁻ uptake by N-deficient turf, reduction occurred primarily in the roots. Between 8 and 16 hours, however, the site of reduction shifted to the shoots. Nitrogen form did not affect partitioning of the absorbed N between roots (40%) and shoots (60%) but did affect growth. Compared to NO₃⁻, NH₄⁺ uptake inhibited root, but not shoot, growth. Total soluble carbohydrates decreased in both roots and shoots during the uptake period, principally the result of fructan metabolism. Ammonium uptake resulted in greater total depletion of soluble carbohydrates in the root compared to NO₃⁻ uptake. The data indicate that N assimilation by ryegrass turf utilizes stored sugars but is also dependent on current photosynthate.     

Rhizosphere pH as a result of nitrogen levels and NH4/NO3 ratio and its effect on zinc availability and on growth of rice flower (Ozothamnus diosmifolius)

The effect of modification of the rhizosphere pH, via solution-N concentration and source, on rice flower (Ozothamnus diosmifolius, Astraceae) growth was investigated in two different experiments. In order to simulate a wide range of pHs easily, the plants were grown in an inert artificial substrate (perlite). In the first the rhizosphere pH was modified through variation of N concentrations and the NH₄/NO₃-N ratio in the irrigation water. In the second the rhizosphere pH was modified solely by altering the NH₄/NO₃-N ratio while irrigation-N concentration was held at the level found to be optimal in the first experiment. Cultivation of rice flower, a new crop in Israel, is hampered by lack of knowledge on its Zn nutrition. Because availability of soil Zn largely depends on pH we investigated in the second experiment the effect of Zn foliar application. The growth of rice flower plants under low-N fertilization or low NH₄/NO₃-N ratio was poor and the plants exhibited growth disorders such as tipburn, severe chlorosis and necrosis. These growth disorders could not be ascribed to any direct effect of N nutrition therefore it was suggested that the indirect effect of the treatments, e.g., the rhizosphere pH dominates rice flower growth through its effect on nutrient availability. The only nutrient that was significantly correlated with pH and yield parameters in both experiments was Zn. All irrigation-nutrients concentrations were within the recommended range for hydroponically grown plants; however, the leaf-Mn concentration of plants grown in pH above 7.5 was in the toxic range while that of Zn was deficient. The high preferential uptake of Mn over Zn by rice flower plants and the question of whether high Mn uptake induced Zn deficiency remain open.     

盐胁迫下不同的钙盐对小麦幼苗耐盐性的影响

利用Ca(N03)2和CaCl2可以提高生长在盐渍条件下小麦幼苗的耐盐能力,增加幼苗的干、鲜重。其原因是由于两种钙盐均能防止膜脂过氧化,降低质膜透性,减少细胞内营养物质外渗,阻止Na+进入细胞。实验结果证明,在降低小麦幼苗盐害方面,Ca(N03)2好于CaCl2。讨论了两个钙盐在降低盐害机理方面的差异。     

Modeling the C Economy of Anabaena flos-aquae: Estimates of Establishment, Maintenance, and Active Costs Associated with Growth on NH(3), NO(3), and N(2)

Steady state cultures of Anabaena flos-aquae were established over a wide range of phosphate-limited growth rates while N was supplied as either NH₃, NO₃⁻, or N₂ gas. At growth rates greater than 0.03 per hour, rates of gross and net carbon fixation were similar on all N sources. However, at lower growth rates (<0.03 per hour) in the NO₃⁻ and N₂ cultures, gross photosynthesis greatly exceeded net photosynthesis. The increase in photosynthetic O₂ evolution with growth rate was greatest when N requirements were met by NO₃⁻ and least when met by NH₃. These results were combined with previously reported measurements of cellular chemical composition, N assimilation, and acetylene reduction (Layzell, Turpin, Elrifi 1985 Plant Physiol 78: 739-745) to construct empirical models of carbon and energy flow for cultures grown at 30, 60, and 100% of their maximal growth rate on all N sources. The models suggested that over this growth range, 89 to 100% of photodriven electrons were allocated to biomass production in the NH₃ cells, whereas only 49 to 74% and 54 to 90% were partitioned to biomass in the NO₃⁻-and N₂-grown cells, respectively. The models were used to estimate the relative contribution of active, maintenance, and establishment costs associated with NO₃⁻ and N₂ assimilation over the entire range of growth rates. The models showed that the relative contribution of the component costs of N assimilation were growth rate dependent. At higher growth rates, the major costs for NO₃⁻ assimilation were the active costs, while in N₂-fixing cultures the major energetic requirements were those associated with heterocyst establishment and maintenance. It was concluded that compared with NO₃⁻ assimilation, N₂ fixation was energetically unfavorable due to the costs of heterocyst establishment and maintenance, rather than the active costs of N₂ assimilation.     

Effects of NaCl and CaCl(2) on Cell Enlargement and Cell Production in Cotton Roots

In many crop species, supplemental Ca²⁺ alleviates the inhibition of growth typical of exposure to salt stress. In hydroponically grown cotton seedlings (Gossypium hirsutum L. cv Acala SJ-2), both length and weight of the primary root were enhanced by moderate salinities (25 to 100 millimolar NaCl) in the presence of 10 millimolar Ca²⁺, but the roots became thinner. Anatomical analysis showed that the cortical cells of these roots were longer and narrower than those of the control plants, while cortical cells of roots grown at the same salinities but in the presence of only 0.4 millimolar Ca²⁺ became shorter and more nearly isodiametrical. Cell volume, however, was not affected by salinities up to 200 millimolar NaCl at either 0.4 or 10 millimolar Ca²⁺. Our observations suggest Ca²⁺-dependent effects of salinity on the cytoskeleton. The rate of cell production declined with increasing salinity at 0.4 millimolar Ca²⁺ but at 10 millimolar Ca²⁺ was not affected by salinities up to 150 millimolar NaCl.     

Dissimilatory Reduction of NO(2) to NH(4) and N(2)O by a Soil Citrobacter sp

Dissimilatory reduction of NO(2) to N(2)O and NH(4) by a soil Citrobacter sp. was studied in an attempt to elucidate the physiological and ecological significance of N(2)O production by this mechanism. In batch cultures with defined media, NO(2) reduction to NH(4) was favored by high glucose and low NO(3) concentrations. Nitrous oxide production was greatest at high glucose and intermediate NO(3) concentrations. With succinate as the energy source, little or no NO(2) was reduced to NH(4) but N(2)O was produced. Resting cell suspensions reduced NO(2) simultaneously to N(2)O and free extracellular NH(4). Chloramphenicol prevented the induction of N(2)O-producing activity. The K(m) for NO(2) reduction to N(2)O was estimated to be 0.9 mM NO(2), yet the apparent K(m) for overall NO(2) reduction was considerably lower, no greater than 0.04 mM NO(2). Activities for N(2)O and NH(4) production increased markedly after depletion of NO(3) from the media. Amendment with NO(3) inhibited N(2)O and NH(4) production by molybdate-grown cells but not by tungstate-grown cells. Sulfite inhibited production of NH(4) but not of N(2)O. In a related experiment, three Escherichia coli mutants lacking NADH-dependent nitrite reductase produced N(2)O at rates equal to the wild type. These observations suggest that N(2)O is produced enzymatically but not by the same enzyme system responsible for dissimilatory reduction of NO(2) to NH(4).     

外源NO对NaCl胁迫下黄瓜幼苗氮化合物和硝酸还原酶活性的影响

采用营养液水培的方法,研究了外源一氧化氮(nitric oxide,NO)对50 mmol?L-1NaCl胁迫下黄瓜(Cucu-mis sativusL.)幼苗根系和叶片内硝酸还原酶(nitrate reductase,NR)活性、硝态氮(NO3--N)、铵态氮(NH4 -N)及可溶性蛋白含量的影响.结果表明:100μmol?L-1外源NO供体硝普钠(sodium nitroprusside,SNP)能明显提高NaCl胁迫下黄瓜幼苗叶片和根系内NR的活性,缓解由于盐胁迫造成的NO3--N含量的下降,减少NH4 -N在植株体内的过量积累,提高渗透调节物质可溶性蛋白的含量,从而减轻由于盐胁迫对黄瓜幼苗植株造成的伤害.     

The effect of sodium salts and pH on hydrogenase activity of the haloalkaliphilic sulfate-reducing bacteria

Hydrogenase is the main catabolic enzyme of hydrogen-utilizing sulfate-reducing bacteria. In haloalkaliphilic sulfate reducers, hydrogenase, particularly if it is periplasmic, functions at high concentrations of Na+ ions and low concentrations of H+ ions. The hydrogenases of the newly isolated sulfate-reducing bacteria Desulfonatronum thiodismutans, D. lacustre, and Desulfonatrovibrio hydrogenovorans exhibit different sensitivity to Na+ ions and remain active at NaCl concentrations between 0 and 4.3 M and NaHCO3 concentrations between 0 and 1.2 M. The hydrogenases of D. lacustre and D. thiodismutans remain active at pH values between 6 and 12. The optimum pH for the hydrogenase of D. thiodismutans is 9.5. The optimum pH for the cytoplasmic and periplasmic hydrogenases of D. lacustre is 10. Thus, the hydrogenases of D. thiodismutans, D. lacustre, and Dv. hydrogenovorans are tolerant to high concentrations of sodium salts and extremely tolerant to high pH values, which makes them unique objects for biochemical studies and biotechnological applications.     

The effect of cocaine on gastric mucosal PGE(2), LTC(4) and ulcerations

The association between cocaine use and acute gastroduodenal perforation is known. The effect of cocaine and stress on gastric mucosal ulceration and the levels of prostaglandin E(2) (PGE(2)) and leukotriene C(4) (LTC(4)) was studied in 40 Sprague-Dawley rats. Controls received intraperitoneal (i.p.) saline, ten received i.p. cocaine (35 mg/kg), ten were stressed by the cold restraint method, and ten had i.p. cocaine and stress. Cocaine alone did not induce ulceration, but decreased PGE(2) levels. Stress alone caused ulceration, but was not associated with a change in either PGE(2) or LTC(4) levels. When combined with stress, however, cocaine caused a three-fold increase in ulceration and a significant increase in PGE(2) and LTC(4) levels. Stress may predispose the cocaine addict to loss of gastroduodenal mucosal integrity, which is related to an imbalance of PGE(2) and LTC(4) synthesis.     

The effects of NaCl and CaCl2 on photosynthesis and growth of alfalfa plants

The effects of 0, 30, 60, and 90 mM NaCl, and 0 and 5 mM CaCl2 on certain parameters of photosynthesis and growth in alfalfa (Medicago sativa L. cv. Ghara yonjeh) plants were studied. The increasing NaCl concentration in the Hoagland nutrient solution decreased the contents of chlorophylls and the net photosynthetic rate, and increased the rate of respiration (RD) and CO2 compensation concentration in the leaves of treated plants. The contents of carotenoids (Car) were not significantly affected. The addition of 5 mM CaCl2 enhanced the RD and increased the Car contents in treated leaves. With the NaCl concentration in the culture medium increasing, the dry matter production in both root and shoot decreased, as well as the relative growth rate (RGR), net assimilation rate (NAR), and leaf area ratio (LAR). The addition of CaCl2 caused a partial elimination of the NaCl effects on the root and shoot, RGR and NAR, and it decreased the LAR.     

The effect of NO3- and NH4 + ions on enzymes involved in nitrogen assimilation inPisum sativum L

Nitrate reductase level in leaves of pea plants is higher than in roots despite of the lower content of endogenous nitrate. Addition of ammonium ions to nutrient solution containing nitrate decreases nitrate reductase level in leaves estimatedin vivo while its level estimatedin vitro is increased. Glutamine synthetase (GS) level in roots decreases during short (24 and 48 h) and long (14 d) term cultivation of seedlings in solutions containing ammonium ions. This decrease occurs in leaves only after the long term influence of ammonium ions. Level of this enzyme is higher in plants grown in the presence of nitrogen (ammonium and nitrate) as compared to those grown without the nitrogen. Level of glutamate dehydrogenase in roots is increased after both short and long term cultivation of plants in the presence of ammonium ions.     

Interaction of cis-[Pt(NH3)2(H2O)2](NO3)2 with ribose deoxyribose diguanosine phosphates

The three diguanosine phosphates GpG (4 X 10(-4) M), d(GpG) (10(-5) M), and d(pGpG) (10(-5) M) have been reacted with cis-[Pt(NH3)2(H2O)2](NO3)2 (1 Pt/dinucleotide) in water at pH 5.5 and 37 degrees C. In each case a single product is formed. The three complexes have been characterized by proton nuclear magnetic resonance (1H NMR) and circular dichroism (CD) analyses. They are N(7)-N(7) chelates of the metal with an anti-anti configuration of the bases. They present a conformational change upon deprotonation of guanine N(1)H whose pKa is ca. 8.7 (D2O). Their CD spectra, compared to those of the free dinucleotides, exhibit an increase of ellipticity in the 275-nm region, which can be qualitatively related to the characteristic increase reported for platinated DNA and poly(dG) . poly(dC). These results are in favor of the hypothesis of intrastrand cross-linking of adjacent guanines, by the cis-PtII(NH3)2 moiety, after a local denaturation of DNA.     

Feasible boundaries of aqueous two-phase systems with NH(3) and CO(2) as recyclable volatile salts

Aqueous two-phase systems (ATPSs) have great potential for use in the downstream processing of fermentation products. A major drawback of these systems, limiting application in industrial practice up till now, is the consumption of large amounts of auxiliary materials such as polymers and salts. Making use of alternative auxiliaries can diminish this relatively large discharge. A possible approach is to make use of volatile salts induced by combinations of ammonia and carbon dioxide that can be recycled to the extraction system. As part of an ongoing research effort on ATPSs with volatile salts, this work aims at getting more information on the system boundaries or operating conditions of these systems in terms of phase behavior. The results show that the NH(3)/CO(2) ratio is an important parameter that has a large influence on the system boundaries. Both for systems with PEG 2000 and PEG 4000, this ratio has to be larger than about 1.75 to make a liquid-liquid phase separation possible. The most optimal ratio seems to be 2.0 for reasons of solution composition and absence of solid salt.     

Plant Characteristics and Nutrient Composition and Mobility of Broccoli (Brassica oleracea var. italica) Supplied with NH4+, NO3"" or NH4NO3

Shelp, B. J. 1987. Plant characteristics and nutrient compositionand mobility of broccoli (Brassica oleracea var. italica) suppliedwith NH⁺₄, NO₃ or NH₄NO₃.—J. exp. Bot. 38: 1603–1618. The effects of varying NH⁺₄, NO₃ or NH₄NO₃ concentration onthe final plant characteristics, element composition, and accumulationof NO₃-N, NH⁺₄-N and organic-N were evaluated in broccoli (Brassicaoleracea var. italicacv. Futura and Premium Crop) plants culturedin vermiculite under greenhouse conditions supplemented withlight. NH⁺₄-grown plants were stunted and exhibited signs ofmarginal necrosis on the old leaves, accompanied by an accumulationof NH4. The tissue levels of N, P, Mn, Cu, Zn and B were generallyincreased by NH⁺₄ versus NO₃ nutrition whereas the reverse wastrue for Ca; Mg and K were only slightly affected, if at all.These results are attributed to: changes in element availabilityresulting from reduced rhizosphere pH due to NH⁺₄uptake ratherthan NO ₃uptake; competition of Ca uptake by NH⁺₄; and dilutionof N by increased vegetative growth with NO₃-nutrition. Theelement concentrations of N, P or K were similar in all tissueswhereas Ca, B and Mn were markedly less in the florets and youngleaves compared to mature leaves; this supports literature indicatingthat the former elements are phloem-mobile whereas the latterare not. Assuming that the nutrient supply for mature leavesis delivered principally via the xylem stream, the data suggestthat nutrients for developing leaves and florets are suppliedpredominantly in the phloem. If so, under our experimental conditions.Zn and Cu were also readily mobile in the phloem whereas Mgmovement was restricted. NH₄⁺ versus NO₄⁺ J nutrition alteredthe distribution of these elements. The two broccoli cultivarstested under the greenhouse environment differed in NH⁺₄ toleranceand in the distribution of K and Cu suggesting there was a geneticbasis for cultivar variation in mineral acquisition and redistribution. Key words: Plant nutrition, phloem mobility, elemental composition.