Lichens as air pollution indicators in the metropolitan area of San José, Costa Rica

Lichens were used as air pollution indicators in the metropolitan area of San José, Costa Rica. Transplants showed a positive correlation between the percentage of dead cells in the thallus and the ketone soluble substances deposited on it. Those parts of the city where pollution is greatest (industrial areas and heavy traffic) were also the ones where lichens suffered the most, and in some extreme cases the thallus died after 8 months of exposure. Besides this transplant experiment, the coverage of Parmelia lichens on the bark of several tree species was determined in some areas of the city. The results of these observations suggest that the city of San José has three different kinds of air environment in relation to lichen survival: normal, transitional and desertic, as reported for other cities of the world. The most frequent air pollutants in San José are: CO, CO2, C2H5OH, Cl2, HCl, H2S, H3PO4, H2CrO4, NO, NH3, NH4 Cl, SO2 and Zn.     

Osmoregulatory role of alanine during salt stress in the nitrogen fixing cyanobacterium Anabaena sp. 287.

The freshwater cyanobacterium, Anabaena sp. 287 exhibited enhanced tolerance to NaCl in the presence of ammonium, nitrate, and the amino acids, alanine, valine, proline, lysine, histidine, methionine and aspartic acid. Apart from providing permanent protection to the growth during stress, like NO3- and NH4+, alanine also relieved the initial salt mediated inhibition on enzymes involved in nitrogen fixation, photosynthesis and respiration. The accumulation of sugars was observed only during molecular nitrogen growth in the presence of salt. The cellular total nitrogen content was inversely proportional to the total sugar concentration. All nitrogenous substances which supported growth in the presence of salt curtailed the Na+ influx. Sodium chloride concentration-dependent [3H]D-alanine uptake in this cyanobacterium favours the conclusion that alanine acts as an osmoregulator along with sugars.     

空气NH3增高情况下不同形式氮源对荫香光合作用和氮利用的影响

 生长在供给NO-3 N、NH+4 N和NH4NO3 N氮源下的荫香（Cinnamomum burmanni）幼树暴露在增高空气NH3浓度下30 d。利用气体交换测定和氮分析研究了植株的光合作用、氮利用和氮在光合过程一些组分中的分配,根据Farquhar-von Caemmerer模式得出相关光合参数。结果表明在增高空气NH3下生长于NO-3 N的植株Rubisco最大羧化速率（Vcmax）和最大光合电子传递速率（Jmax）较正常空气下的高,但生长于NH+4 N和NH4NO3 N的植株则较正常空气下的低。无论生长于何种形式氮下的植株,在空气NH3增高下以单位叶面积为基准的叶氮含量（Na）显著增高（p<0.05）。在增高空气NH3下,生长于NO-3 N下的植株,其类囊体氮量（NT）、Rubisco氮（NR）和结合于光合电子传递链的氮（NE）的含量较正常空气下的增高（p<0.05）;而生长于NH+4 N和NH4NO3 N下的植株则较正常空气下的低。表明在空气NH3增高下生长于NO－3 N的植株能有效地利用氮合成光合过程必要的组份,而生长于NH+4 N和NH4NO－3 N的植株氮在NT、NR和NE的分配受到部分限制。在空气NH3增高下生长于NO－3 N和NH4NO3 N的植株,其以单位干重为基准的有机氮量较正常空气下的高,但生长于NH+4 N的植株则较正常空气下的低,此外在空气NH3增高下生长于NO－3 N的植株的可溶性蛋白氮较正常空气下增高,而生长在NH+4 N的植株亦见降低。结果表明空气NH3增高可能有利于NO－3 N下生长的荫香植株利用空气中的氮,促进叶片光合速率提高,而空气NH3增高能抑制NH+4 N或NH4NO3 N下生长的荫香植株光合作用和氮的利用和再分配。     

Metabolic recovery of continental antarctic cryptogams after winter

The activation of metabolism after the winter period was investigated in several mosses and lichens in continental Antarctica. Thalli that were still in their over-wintering inactive state in early spring were sprayed artificially and the time-dependent activation of photosystem II (PSII), carbon fixation and respiration was determined using gas exchange and chlorophyll a fluorescence techniques. The investigated lichens recovered PSII activity almost completely within the first few minutes and gross photosynthesis was fully reactivated within a few hours. In contrast, photosynthesis took much longer to recover in mosses, which could indicate a general difference between the green-algal symbionts in lichens and moss chloroplasts. Only small and quickly reversible increased rates of respiration were observed for the foliose lichen Umbilicaria aprina from a more xeric habitat. In contrast, species occurring near persistent meltwater, such as the moss Bryum subrotundifolium and the lichen Physcia caesia, had highly increased respiration rates that were maintained for several days after activation. Calculation of the carbon balances indicated that the activation pattern strongly dictated the length of time before a carbon gain was achieved. It appears that the differences in recovery reflect the water relations of the main growth period in summer.     

Estimation of cytoplasmic nitrate and its electrochemical potential in barley roots using 13NO3 and compartmental analysis

13NO3 was used to determine the intracellular compartmentation of NO3 in barley roots (Hordeum vulgare cv. Klondike), followed by a thermodynamic analysis of nitrate transport.Plants were grown in one-tenth Johnson's medium with 1 mol m3 NO3 (NO3-grown plants) or 1 mol m3 NH4NO3 (NH4NO3-grown plants).The cytoplasmic concentrations of NO3 in roots were only approx. 3-6 mol m3 (half-time for exchange approx. 21 s) in both NO3 and NH4NO3 plants. These pool sizes are consistent with published nitrate microelectrode data, but not with previous compartmental analyses.The electrochemical potential gradient for nitrate across the plasmalemma was +26 +/-1 kJ mol1 in both NO3- and NH4NO3-grown plants, indicating active uptake of nitrate. At an external pH of 6, the plasmalemma electrochemical potential for protons would be approx. -29 +/- 4 kJ mol1. If the cytoplasmic pH was 7.3 +/- 0.2, then 2H+/1NO3 cotransport, or a primary ATP-driven pump (2NO3/1ATP), are both thermodynamically possible. NO3 is also actively transported across the tonoplast (approx. +6 to 7 kJ mol1).     

Hardening by partial dehydration and ABA increase desiccation tolerance in the cyanobacterial lichen Peltigera polydactylon

* BACKGROUND AND AIMS: The ability of partial dehydration and abscisic acid pretreatments to increase desiccation tolerance in the cyanobacterial lichen Peltigera polydactylon was tested. * METHODS: Net photosynthesis and respiration were measured using infrared gas analysis during a drying and rehydration cycle. At the same time, the efficiency of photosystem two was measured using chlorophyll fluorescence, and the concentrations of chlorophyll a were spectrophotometrically assayed. Heat production was also measured during a shorter drying and rehydration cycle using differential dark microcalorimetry. * KEY RESULTS: Pretreating lichens by dehydrating them to a relative water content of approx. 0.65 for 3 d, followed by storing thalli hydrated for 1 d in the light, significantly improved their ability to recover net photosynthesis during rehydration after desiccation for 15 but not 30 d. Abscisic acid pretreatment could substitute for partial dehydration. The improved rates of photosynthesis during the rehydration of pretreated material were not accompanied by preservation of photosystem two activity or chlorophyll a concentrations compared with untreated lichens. Partial dehydration and ABA pretreatments appeared to have little direct effect on the desiccation tolerance of the mycobiont, because the bursts of respiration and heat production that occurred during rehydration were similar in control and pretreated lichens. * CONCLUSIONS: Results indicate that the photobiont of P. polydactylon possesses inducible tolerance mechanisms that reduce desiccation-induced damage to carbon fixation, and will therefore improve the supply of carbohydrates to the whole thallus following stress. In this lichen, ABA is involved in signal transduction pathways that increase tolerance of the photobiont.     

Interactive effects of UV-B and Cu on photosynthesis,uptake and metabolism of nutrients in a green alga Chlorella vulgaris under simulated ozone column

This study demonstrated a general reduction in photosynthesis (carbon fixation, O(2)-evolution and photochemical electron transport chain), the uptake of NH(4)(+), NO(3)(-), urea and PO(4)(3+), and activities of nitrate reductase, urease, acid phosphatase and ATPase following UV-B and copper exposure of Chlorella vulgaris in the absence or presence of 1 and 2 ppm concentrations of a 4-inch-thick ozone layer. Though the effect of stressors used in combination was very detrimental to the above processes, selected concentrations of ozone not only counteracted the UV-B-induced inhibition of the above processes, but also stimulated O(2)-evolution and the photochemical electron transport chain. Kinetics of nutrient uptake and enzyme activities demonstrated that UV-B causes structural change(s) in the enzymes/carriers responsible for the uptake of NH(4)(+), NO(3)(-), urea and PO(4)(3+) as well as their assimilatory enzymes. Except for nitrate reductase, copper was found to compete for the binding sites of all the above enzymes. Synergistic inhibition of photosynthetic activity, nutrient (except NH(4)(+)) uptake, and enzyme activities by UV-B+Cu seems to be due to increased Cu uptake as a consequence of altered membrane permeability brought about by the peroxidation of membrane lipids in UV-B-exposed cells.     

The influence of pretreatment with different cations on anaerobic nitrite production by excisedPisum sativum roots

The influence of pretreatment with some cations on anaerobic nitrite production (in an assay medium lacking nitrate) by excised primary roots of pea (Pisum sativum L., ov. Raman), detached from six-day-old seedlings germinated in distilled water, was investigated. When the excised roots were precultivated in one-salt-solutions of KNO3, then these roots produced at 9 mM and 15 mM NO3- concentrations under anaerobic conditions significantly more NO2-, than those precultivated in a nutrient solution containing besides K+ ions also Ca2+ and Mg2+ ions, and they produced nitrite for a longer time. The KNO3 dependent increase in anaerobic NO2- production was counteracted most by Ca2+ and to a lesser extent by Mg2+; Na+ was without effect. NH4+ at higher concentrations (12 and 15 mM) significantly depressed nitrite production both by roots precultivated in a solution containing besides NH4+ only K+, and by roots precultivated in a full nutrient solution containing K+, Ca2+ and Mg2+, however at lower NH4+ concentrations (0.6 and 2mMNH4+; 15mMNO3-) the decrease was more conspicuous in the KNO3 solution than in the full nutrient solution. Nitrate reductase level was not influenced by this pretreatment. When 6% and 7.5% n-propanol, which increases membrane permeability and causes mixing of storage and metabolic nitrate pools in the cells, was added to the assay medium lacking nitrate, anaerobic nitrite production increased and the differences caused by the precultivation disappeared. These results show that higher K+ concentrations in unbalanced one-salt-solutions of KNO3 can cause higher membrane permeability by accentuating Ca8+ deficiency, which results in a faster penetration of NO3- from the storage pool to the sites of its reduction and in an easier penetration of NO2- out of the roots, and that higher NH4+ concentrations can change nitrate compartmentation and diminish the metabolic NO3- pool which results in a slower nitrate reduction. Besides that, lower NH4+ concentrations in KNO3 solutions (15mMNO3-) probably partially counteract the K+ dependent increase in membrane permeability. The results obtained show that there is no simple, direct relationship between the so-called metabolic pool of nitrate (i.e. anaerobic nitrite production) and the level of nitrate reductase, but that the velocity of nitrate reduction can be influenced by nitrate compartmentation in the cell.     

Differential effects of lichens,mosses and grasses on respiration and nitrogen mineralization in soils of the New Jersey Pinelands

In the New Jersey Pinelands, severely disturbed areas often do not undergo a rapid succession to forest; rather, a patchy cover of lichens, mosses and grasses persists for decades. We hypothesized that these plant covers affect soil microbial processes in different ways, and that these effects may alter the successional dynamics of the patches. We predicted that the moss and grass covers stimulate soil microbial activity, whereas lichens inhibit it, which may in turn inhibit succession. We collected soil cores from beneath each type of cover plus bare soil within two types of highly disturbed areas—sites subjected to hot wildfires, and areas mined for sand. Organic matter (OM) content, soil respiration and potential N mineralization were measured in the cores. Soils under mosses were similar to those under grasses; they accumulated more OM and produced more mineral N, predominantly in the form of ammonium, than either the bare soils or the soils beneath lichens. Mineralization under lichens, like that of the bare soils but unlike the soils beneath mosses or grasses, was dominated by net nitrification. These patterns were reproduced in experimentally transplanted moss and lichen mats. Mosses appear to create high-nutrient microsites via high rates of OM accumulation and production of ammonium, whereas lichens maintain low-nutrient patches similar to bare soil via low OM accumulation rates and production of mineral N predominantly in the mobile nitrate form. These differences in soil properties may explain the lack of vascular plant invasion in lichen mats, in contrast to the moss-dominated areas.     

Effects of inorganic nitrogen on C2H2 reduction and CO2 exchange in the Peltigera praetextata-Nostoc and Peltigera aphthosa-Coccomyxa-Nostoc symbioses

Uptake of NH ₄ ⁺ and NO ₃ ^- by the N₂-fixing lichens Peltigera praetextata (two-component lichen) and P. aphthosa (three-component lichen) was studied. In addition, the effects of these ions, separately and in combination, on C₂H₂ reduction and CO₂ exchange were examined. Both NH ₄ ⁺ and NO ₃ ^- were utilized by the lichens. NH₄NO₃ caused an increased liberation of NO ₃ ^- from the lichens as compared to the release observed in untreated lichen thalli. NH ₄ ⁺ and NO ₃ ^- led to reduced C₂H₂ reduction by P. praetextata, which, however, was less pronounced than when the two ions were given in combination. In P. aphthosa the C₂H₂ reduction was inhibited by NH ₄ ⁺ and NH₄NO₃, but not by NO ₃ ^- alone. NH ₄ ⁺ and NO ₃ ^- had no effect on the net photosynthesis of P. praetextata, while, in combination, they led to inhibition, although only at a concentration higher than that inhibitory to the C₂H₂ reduction of P. aphthosa. The photsynthesis was inhibited by all salts, but only initially, probably a salt effect. Effects of NH ₄ ⁺ on the membrane potential of the cyanobiont are suggested as an important factor causing the depression of net photosynthesis.     

不同覆盖方式对底泥内源营养盐释放的控制效果

通过底泥内源营养盐释放控制室内模拟试验,考察了塑料包被、斜发沸石、方解石、石英砂和硝酸钙5种覆盖材料对底泥氮磷释放效率的影响,系统分析了各自优劣程度,为实际环境中不同污染背景水体选择适宜的控制技术提供科学依据.结果表明: 不同覆盖材料对底泥总磷释放的控制效果依次为:塑料包被>硝酸钙>斜发沸石>方解石>石英砂;不同覆盖材料对底泥总氮释放的控制效果依次为:斜发沸石>塑料包被>方解石>石英砂>硝酸钙;不同覆盖材料对底泥硝态氮释放的控制效果依次为:塑料包被>斜发沸石>方解石>石英砂>硝酸钙;不同覆盖材料对底泥铵态氮释放的控制效果依次为:硝酸钙>石英砂>斜发沸石>方解石>塑料包被;温度和底泥内源营养盐释放有对应关系,水样中总磷、总氮和硝态氮浓度会随着温度上升而增加,而铵态氮浓度呈下降趋势.     

The position of nitrate respiration in evolution

Egami's hypothesis that oxygen respiration evolved from nitrate respiration, and this from nitrate fermentation, is not accepted. The reasons are: (1) Presumably there was no nitrate before O₂ in the biosphere. (2) On mechanistic grounds, respiration (oxidative phosphorylation) is to be derived directly from photosynthesis (photosynthetic phosphorylation) rather than from any form of fermentation.     

The effect of nitrate and ammonium concentrations on growth and alkaloid accumulation of Atropa belladonna hairy roots

The growth, the alkaloid production, as well as the scopolamine/hyoscyamine ratio of two clones of belladonna hairy roots were studied. The effects of nitrate and ammonium concentrations on these cultures were investigated. A rise in ammonium concentration caused the decline of the hairy roots, while nitrate had a marked effect on the alkaloid content. The alkaloid production obtained with 15.8 mM of NO3- and 20.5 mM of NH4+ was 1.2-1.4 times higher than that obtained when the roots were grown in the standard Murashige and Skoog medium (MS medium, 39.5 mM of NO3- and 20.5 mM of NH4+). The nitrate and ammonium concentrations in the culture medium also had a strong influence on the scopolamine/hyoscyamine ratio. When nitrate or ammonium concentrations were raised, that ratio also was increased 2-3-fold. The hairy root clones originating from transformations with two distinct strains of Agrobacterium had similar responses.     

形态对不同小麦基因型氮素吸收的光合作用的影响

利用水培试验,研究了3个小麦基因型对不同形态N素吸收和积累的差异,结果表明,在不同N浓度优势,与次敏感型莱州953和钝感到江东门相比,敏感型扬麦158不仅具有较强的NO3^-和NH4^ 吸收能力,而且具有最强的增铵营养吸收能力,增铵营养促进了扬麦158和莱州953对NO3^-和NH4^ 的吸收,但在一定程度上抑制了江东门对NO3^-的吸收,与NO3^-营养及NH4^ 营养相比,增铵营养显著提高了杨表158和莱州953的全株、地上部N积累量和叶片合速率,而对江东门影响较小,因此,增铵营养促进了植株的N吸收,提高了N积累和光合速率,从而促进了小麦生长。     

Vegetation and ecology of ice-free areas of Northern Victoria Land,Antarctica

Summary At Birthday Ridge, a small ice free area in northern Victoria Land (70°48S, 167°00E), cryptogamic vegetation is mostly confined to gaps between granitc rocks. The sheltering effect on lichens and mosses was analyzed by continuous measurements of the microclimate at various levels between the rocks. Although warming by solar radiation was favourable for the existence of cryptogams, rocks strongly insolated were mostly devoid of lichens and mosses. Lichens in the soaked active state were heated to above air temperature but did not reach more than 10°C. The presence of lichens was dependent on the moisture conditions of the habitat. It was observed that snow, the only source of moisture, accumulated in summer only in deeper levels between rocks, and that the snow rapidly melted on contact with the lichens. After a snow shower,Usnea sulphurea gained 67% andUmbilicaria decussata 94% of their maximum water capacity. During one quarter of the time period of 7 days the lichens were soaked and therefore capable of carrying out photosynthesis. The lichens in soaked state had always less than optimum temperatures for net photosynthesis. The rock gaps at Birthday Ridge form oases, the only localities where moisture is provided, and temperature is high enough to enable growth of lichens and mosses.Bryum is also able to exist in the upper 3 cm of soil.     

Influence of Elevated CO2 Concentration and Nitrogen Source on Photosynthetic Traits in the Invasive Species Eupatorium adenophorum (Asteraceae)

Increases in the concentration of atmospheric CO2 and plant invasion are two important problems that face humans worldwide. In some plants, exposure to a short term elevated concentration of CO2 (SE［CO2］) promotes photosynthesis, but the promotion of elevated ［CO2］ (E ［CO2］) to photosynthesis might disappear after long term treatment (so called “CO2 acclimation”); this might result from the associated inhibition of nitrate assimilation. The present study investigated the physiological effects of short term (8 days) and long term (40 days) exposure to E［CO2］ when these were combined with different forms of inorganic N (full N; nitrate (NO3-) N) in the invasive species Eupatorium adenophorum. Exposure to E［CO2］ increased the biomass of Eadenophorum, regardless of the duration of exposure to E［CO2］ and the type of inorganic N that was supplied. E［CO2］ could promote the photosynthesis of Eadenophorum seedlings fertilised with non depleted Hoagland solutions (full N). For plants fertilised with NH4+ depleted Hoagland solution (NO3- N), LE［CO2］ treatment promoted the photosynthesis of Eadenop horum, but the promotion of photosynthesis by E［CO2］ disappeared under SE［CO2］ conditions. Photosynthetic pigments contents were determined to estimate potential changes in the photosynthetic capacity of Eadenophorum. For plants fertilised with non depleted Hoagland solution, there were no significant differences in chlorophyll among the three ［CO2］ treatments, but the treatment of SE［CO2］ increased the levels of chlorophyll in leaves. The apparent promotion of biomass accumulation and photosynthesis at LE［CO2］ without a decrease in chlorophyll indicates that Eadenophorum might not acclimate to long term exposure to E［CO2］. NH4+ depletion did not affect the capacity of LE［CO2］ to promote the photosynthesis of Eadenophorum. Thus, considering some plants fertilised with NO3- acclimating to LE［CO2］, Eadenophorum might be more competitive in areas where the soils are relatively poor in NH4+ as levels of atmospheric CO2 continue to rise.     

RATE OF PHOTOSYNTHESIS AND RESPIRATION IN DIFFERENT LICHEN TISSUES BY THE CARTESIAN DIVER TECHNIQUE

The Cartesian diver technique has been used for measuring respiration in Protozoa, small crustaceans, insects, and in animal tissue; it can also be used to measure both respiration and photosynthesis in unicellular plants and in plant tissues. In two lichens, Peltigera canina and Evernia prunastri, algal-containing tissues were more than 2½ times as active metabolically as medulla. In Peltigera, cortex was slightly more active, rhizines about equally active, and apothecia about a tenth as active as medulla. Light compensation point and peak rates of apparent photosynthesis were reached at higher light intensities in Evernia than in Peltigera. In both lichens, light seemed to retard respiration in the medulla.     

Seasonal dynamics of N in two Sphagnum moss species and the underlying peat treated with 15NH415NO3

Uptake of 15N labelled NH4NO3 by two Sphagnum mosses on a raised bog in north east Scotland was measured at different times of the year. In a field experiment, fortnightly additions of NH4NO3 at natural abundance, equivalent to 3 g N m-2 yr-1, were made over 14 months to cores of Sphagnum capillifolium occupying hummocks and S. recurvum colonizing hollows. Pre-harvested cores were treated with 15NH415NO3 two weeks before harvesting and 15N abundance determined for the total N in the moss, inorganic and dissolved organic N (DON) in the moss water and extractable inorganic, organic and microbial N in the underlying peat. The proportion of added 15N taken up by the mosses two weeks after each addition averaged 72% and ranged between 11 and 100%, tending to be least during October when the rising water table reached the surface, particularly for S. recurvum. A small proportion of the 15N was detected in the moss water as NH4+ (0.01%) and as DON (0.03%) and on occasions a large proportion remained unaccounted for. In waters from S. capillifolium, DON was proportional to the amount of inorganic N added, but this was not the case for S. recurvum. Little or no 15N was detected in the underlying peat partly because of the large size and variability of the NH4+, DON and microbial N pools.     

Correlating on-line monitoring parameters, pH, DO and ORP with nutrient removal in an intermittent cyclic process bioreactor system

The paper presents the study correlating the profile of on-line monitoring parameters and nutrient removal in an intermittent cyclic process bioreactor (ICPBR) system, thereby utilizing the parameters as operational tool. A laboratory scale ICPBR was employed to treat low C/N ratio domestic wastewater from a township. The study was conducted for correlating biological nutrient removal and on-line monitored parameters pH, dissolved oxygen (DO) and oxidation-reduction potential (ORP). The results revealed that pH, DO and ORP related with the dynamic behavior of nutrient concentration (NH4-N, NO3-N, and PO4-P) during treatment in an ICPBR system. The variation in pH and ORP of the reactor liquor correlate to conversion of ammonia (NH4-N) and nitrate (NO3-N) concentrations, respectively. As the bioconversion of ammonia nitrogen and phosphorus are related to the varying profile of the on-line monitored parameters, the profiles could possibly be used as onsite process control parameters.     

Comparisons of photosynthesis-related traits among understory lichens,mosses and vascular plant leaves in a high-elevation subalpine forest

对比高海拔亚高山森林林下地衣、藓类及维管植物叶片的光合相关性状 在高海拔亚高山森林中，许多地衣和藓类植物欣欣向荣，甚至成为林地表层的优势物种。尽管它们在森林生态系统中承担着不可替代的功能，但我们对其光合作用相关的功能性状水平知之甚少，对相同生境下藓类植物和维管植物的比较研究也较为匮乏。因此，本研究选择中国青藏高原东缘亚高山林下常见的3种地衣、3种藓类和4种维管植物，测定并对比了它们的碳、氮、磷含量及化学计量比、单位面积光合组织干重、叶绿素含量及光合光响应曲线的异同。研究结果表明，林下地衣的氮含量高于藓类植物，二者的氮、磷、叶绿素、光合速率及光合氮利用效率均低于维管植物叶片。不同种类地衣的光合相关性状与其生长环境相符，而林地表层的3种藓类植物和3种草本植物的功能性状在各自功能群中的种间差异均不显著。总之，这些结果表明高海拔亚高山林下地衣和藓类植物的优势与其光合相关性状关系不大，对严酷环境较强的适应能力可能是它们得以繁荣生长的关键。