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Stanley D. Smith - One of the best experts on this subject based on the ideXlab platform.
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effects of enhanced summer monsoons nitrogen deposition and soil disturbance on Larrea tridentata productivity and subsequent herbivory in the mojave desert
2012Co-Authors: Cheryl Vanier, Beth A Newingham, Therese N Charlet, Stanley D. SmithAbstract:Important global change factors in the Mojave Desert include altered precipitation, nitrogen deposition and soil disturbance. We examined the effects of enhanced summer monsoons, nitrogen deposition, and decreased nitrogen inputs via soil disturbance on Larrea tridentata productivity, reproduction, and herbivory. Larrea growth increased with summer monsoons in the dry years of 2004 and 2006, while Larrea growth decreased with summer monsoons in the wet year of 2005. Contrary to predictions, nitrogen addition only increased branch production in the summer of 2005. Combined treatments of monsoons and nitrogen did not result in enhanced growth or reproduction. Disturbance, which was intended to decrease N inputs from biological soil crust, decreased stem elongation in 2005. No treatments affected Larrea reproduction or insect herbivory. Substantial branch-level herbivory by mammals was observed, which significantly increased in the fall of 2005 and 2006, particularly with enhanced monsoons. While nitrogen addition alone had no effect, the addition of water and nitrogen significantly increased branch removal. Our results suggest that increased summer monsoons and nitrogen deposition may result in only small growth increases by Larrea in the Mojave Desert. However, any biomass gains are likely to be lost due to extensive mammalian herbivory with water and nitrogen additions.
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enhanced monsoon precipitation and nitrogen deposition affect leaf traits and photosynthesis differently in spring and summer in the desert shrub Larrea tridentata
2006Co-Authors: D H Barker, Elke Naumburg, Beth A Newingham, Cheryl Vanier, Therese N Charlet, K M Nielsen, Stanley D. SmithAbstract:Summary • Leaf-level CO2 assimilation (Aarea) can largely be predicted from stomatal conductance (gs), leaf morphology (SLA) and nitrogen (N) content (Narea) in species across biomes and functional groups. • The effects of simulated global change scenarios, increased summer monsoon rain (+H2O), N deposition (+N) and the combination (+H2O +N), were hypothesized to affect leaf trait-photosynthesis relationships differently in the short- and long-term for the desert shrub Larrea tridentata. • During the spring, +H2O and +H2O +N plants had lower Aarea and gs, but similar shoot water potential (Ψshoot) compared with control and +N plants; differences in Aarea were attributed to lower leaf Narea and gs. During the summer, +H2O and +H2O +N plants displayed higher Aarea than control and +N plants, which was attributed to higher Ψshoot, gs and SLA. Throughout the year, Aarea was strongly correlated with gs but weakly correlated with leaf Narea and SLA. • We concluded that increased summer monsoon had a stronger effect on the performance of Larrea than increased N deposition. In the short term, the +H2O and +H2O +N treatments were associated with increasing Aarea in summer, but also with low leaf Narea and lower Aarea in the long term the following spring.
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Photosynthetic responses of Larrea tridentata to seasonal temperature extremes under elevated CO2
2004Co-Authors: Elke Naumburg, Michael E. Loik, Stanley D. SmithAbstract:Summary • Elevated CO 2 potentially decreases the effects of temperature stress on photosynthesis. Under both freezing and high temperatures previous studies have shown that elevated CO 2 can particularly enhance photosynthetic rates, although results from freezing studies are more variable. • Here we show gas exchange responses of Larrea tridentata to elevated CO 2 over a 6-yr period when temperature stress events may have had a significant effect on photosynthesis in the field. • Nighttime freezing air temperatures decreased subsequent daytime photosynthetic rates, stomatal conductance, and the maximum yield of PSII similarly under ambient and elevated CO 2 . Further, we found no statistically significant relationship between leaf temperature and photosynthetic enhancement. Overall, the degree of photosynthetic enhancement under elevated CO 2 was directly proportional to the response of stomatal conductance to CO 2 . • Thus, elevated CO 2 does not significantly affect apparent physiological responses of Larrea to temperature extremes. However, because of the tight relationship between stomatal conductance and photosynthetic enhancement, potential climate change effects on stomatal conductance will significantly influence Larrea performance in the future.
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photosynthetic responses of mojave desert shrubs to free air co2 enrichment are greatest during wet years
2003Co-Authors: Elke Naumburg, Michael E. Loik, Travis E. Huxman, Therese N Charlet, David C Housman, Stanley D. SmithAbstract:It has been suggested that desert vegetation will show the strongest response to rising atmospheric carbon dioxide due to strong water limitations in these systems that may be ameliorated by both photosynthetic enhancements and reductions in stomatal conductance. Here, we report the long-term effect of 55 Pa atmospheric CO2 on photosynthesis and stomatal conductance for three Mojave Desert shrubs of differing leaf phenology (Ambrosia dumosa—drought-deciduous, Krameria erecta—winter-deciduous, Larrea tridentata—evergreen). The shrubs were growing in an undisturbed ecosystem fumigated using FACE technology and were measured over a four-year period that included both above and below-average precipitation. Daily integrated photosynthesis (Aday) was significantly enhanced by elevated CO2 for all three species, although Krameria erecta showed the greatest enhancements (63% vs. 32% for the other species) enhancements were constant throughout the entire measurement period. Only one species, Larrea tridentata, decreased stomatal conductance by 25–50% in response to elevated CO2, and then only at the onset of the summer dry season and following late summer convective precipitation. Similarly, reductions in the maximum carboxylation rate of Rubisco were limited to Larrea during spring. These results suggest that the elevated CO2 response of desert vegetation is a function of complex interactions between species functional types and prevailing environmental conditions. Elevated CO2 did not extend the active growing season into the summer dry season because of overall negligible stomatal conductance responses that did not result in significant water conservation. Overall, we expect the greatest response of desert vegetation during years with above-average precipitation when the active growing season is not limited to ∼2 months and, consequently, the effects of increased photosynthesis can accumulate over a biologically significant time period.
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ecological responses of two mojave desert shrubs to soil horizon development and soil water dynamics
2002Co-Authors: Erik P Hamerlynck, Joseph R Mcauliffe, Eric V Mcdonald, Stanley D. SmithAbstract:In the arid southwestern United States, subtle differences in soil horizon development affect seasonal soil hydrology and consequently influence plant performance and community structure. We measured canopy development, population structure, and seasonal ecophysiology (predawn water potential, ψpd, and midday net photosynthetic assimilation, Anet) of two co-dominant warm-desert shrubs, the evergreen Larrea tridentata and drought-deciduous Ambrosia dumosa, in five Mojave Desert soils varying in surface and sub-surface soil development, and we used process-based soil hydrology modeling output to determine longer-term soil water dynamics underlying soil/plant responses. We hypothesized that ecophysiological performance would covary with plant development, which would reflect soil hydrological characteristics. Among three sites on alluvial fan deposits of different geological ages (Young Alluvial, <4000 yr BP; Intermediate Alluvial, ∼12 000 yr BP; Old Alluvial, ∼40 000 yr BP), total canopy volume of Larrea (c...
Blas Micalizzi - One of the best experts on this subject based on the ideXlab platform.
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Actividad antifungica de extractos de plantas usadas en medicina popular en Argentina
2013Co-Authors: Roberto Davicino, María Aída Mattar, Yolanda Angelina Casali, Silvia Graciela Correa, Elisa Margarita Pettenati, Blas MicalizziAbstract:Los hongos pueden causar enfermedades en humanos, especialmente en pacientes inmunosuprimidos. En este estudio, extractos de 10 plantas utilizadas en medicina popular en Argentina fueron ensayadas para estudiar la actividad antifúngica in vitro contra 4 cepas de hongos. De todas las plantas testeadas, solo 4 mostraron actividad antifúngica: Larrea divaricata Cav, Gnaphalium gaudichaudianum D.C, Baccharis trimera Less y Schinus terebenthifolius
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in vivo immunomodulatory effects of aqueous extracts of Larrea divaricata cav
2007Co-Authors: Roberto Davicino, Aida Mattar, Yolanda Casali, Carina Porporatto, Silvia G Correa, Blas MicalizziAbstract:Several medicinal plants are considered immunomodulatory as they display a variety of anti-inflammatory, antimicrobial and antitumoral effects. Larrea divaricata Cav. (jarilla) (Zygophyllaceae) is a plant widely used in popular medicine to treat tumors, infections, and inflammatory diseases. So far, the immunostimulating activities of Larrea divaricata have not been studied in vivo. In this work, we used healthy mice to assess the immunomodulatory potential of aqueous extracts of Larrea divaricata Cav. We found that Decoction (D) and Infusion (I) from Larrea divaricata Cav showed any acute hepatotoxic activity. Only D at 0.5 mg/kg increased the carrageenan-induced inflammation. Macrophages harvested from treated mice showed no signs of apoptosis. These cells showed a significant increase in NO and TNF-alpha release and exhibited the strongest expression of iNOS. Decoction also increased the phagocytosis of zymosan and the binding of LPS-FITC. The expression of CD14, TLR4 and CR3 was lower in macrophages of mice treated than in controls. Thus, Larrea divaricata was able to prime Mphi in vivo and to induce full activation in vitro. Our finding contribute to characterize the biological activity of Larrea divaricata and to understand the ability of these extracts to enhance immune responses.
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antimicrobial activity of aqueous extracts of Larrea divaricata cav jarilla against helicobacter pylori
2006Co-Authors: Patricia W Stege, Roberto Davicino, Yolanda Casali, Silvia G Correa, A E Vega, Blas MicalizziAbstract:We studied here the effect of aqueous extracts of Larrea divaricata Cav on the growth of Helicobacter pylori. Results show that cold extract, infusion, decoction and simulated digestion had inhibitory activity at 0.04-0.1 mg/l against clarithromycin and metronidazole susceptible and resistant H. pylori strains. These results support the popular use of L. divaricata Cav in gastric disturbances and prompt further research to characterize these compounds with a therapeutic potential against gastric ulcers and gastric cancer associated with H. pylori.
Elke Naumburg - One of the best experts on this subject based on the ideXlab platform.
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enhanced monsoon precipitation and nitrogen deposition affect leaf traits and photosynthesis differently in spring and summer in the desert shrub Larrea tridentata
2006Co-Authors: D H Barker, Elke Naumburg, Beth A Newingham, Cheryl Vanier, Therese N Charlet, K M Nielsen, Stanley D. SmithAbstract:Summary • Leaf-level CO2 assimilation (Aarea) can largely be predicted from stomatal conductance (gs), leaf morphology (SLA) and nitrogen (N) content (Narea) in species across biomes and functional groups. • The effects of simulated global change scenarios, increased summer monsoon rain (+H2O), N deposition (+N) and the combination (+H2O +N), were hypothesized to affect leaf trait-photosynthesis relationships differently in the short- and long-term for the desert shrub Larrea tridentata. • During the spring, +H2O and +H2O +N plants had lower Aarea and gs, but similar shoot water potential (Ψshoot) compared with control and +N plants; differences in Aarea were attributed to lower leaf Narea and gs. During the summer, +H2O and +H2O +N plants displayed higher Aarea than control and +N plants, which was attributed to higher Ψshoot, gs and SLA. Throughout the year, Aarea was strongly correlated with gs but weakly correlated with leaf Narea and SLA. • We concluded that increased summer monsoon had a stronger effect on the performance of Larrea than increased N deposition. In the short term, the +H2O and +H2O +N treatments were associated with increasing Aarea in summer, but also with low leaf Narea and lower Aarea in the long term the following spring.
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Photosynthetic responses of Larrea tridentata to seasonal temperature extremes under elevated CO2
2004Co-Authors: Elke Naumburg, Michael E. Loik, Stanley D. SmithAbstract:Summary • Elevated CO 2 potentially decreases the effects of temperature stress on photosynthesis. Under both freezing and high temperatures previous studies have shown that elevated CO 2 can particularly enhance photosynthetic rates, although results from freezing studies are more variable. • Here we show gas exchange responses of Larrea tridentata to elevated CO 2 over a 6-yr period when temperature stress events may have had a significant effect on photosynthesis in the field. • Nighttime freezing air temperatures decreased subsequent daytime photosynthetic rates, stomatal conductance, and the maximum yield of PSII similarly under ambient and elevated CO 2 . Further, we found no statistically significant relationship between leaf temperature and photosynthetic enhancement. Overall, the degree of photosynthetic enhancement under elevated CO 2 was directly proportional to the response of stomatal conductance to CO 2 . • Thus, elevated CO 2 does not significantly affect apparent physiological responses of Larrea to temperature extremes. However, because of the tight relationship between stomatal conductance and photosynthetic enhancement, potential climate change effects on stomatal conductance will significantly influence Larrea performance in the future.
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photosynthetic responses of mojave desert shrubs to free air co2 enrichment are greatest during wet years
2003Co-Authors: Elke Naumburg, Michael E. Loik, Travis E. Huxman, Therese N Charlet, David C Housman, Stanley D. SmithAbstract:It has been suggested that desert vegetation will show the strongest response to rising atmospheric carbon dioxide due to strong water limitations in these systems that may be ameliorated by both photosynthetic enhancements and reductions in stomatal conductance. Here, we report the long-term effect of 55 Pa atmospheric CO2 on photosynthesis and stomatal conductance for three Mojave Desert shrubs of differing leaf phenology (Ambrosia dumosa—drought-deciduous, Krameria erecta—winter-deciduous, Larrea tridentata—evergreen). The shrubs were growing in an undisturbed ecosystem fumigated using FACE technology and were measured over a four-year period that included both above and below-average precipitation. Daily integrated photosynthesis (Aday) was significantly enhanced by elevated CO2 for all three species, although Krameria erecta showed the greatest enhancements (63% vs. 32% for the other species) enhancements were constant throughout the entire measurement period. Only one species, Larrea tridentata, decreased stomatal conductance by 25–50% in response to elevated CO2, and then only at the onset of the summer dry season and following late summer convective precipitation. Similarly, reductions in the maximum carboxylation rate of Rubisco were limited to Larrea during spring. These results suggest that the elevated CO2 response of desert vegetation is a function of complex interactions between species functional types and prevailing environmental conditions. Elevated CO2 did not extend the active growing season into the summer dry season because of overall negligible stomatal conductance responses that did not result in significant water conservation. Overall, we expect the greatest response of desert vegetation during years with above-average precipitation when the active growing season is not limited to ∼2 months and, consequently, the effects of increased photosynthesis can accumulate over a biologically significant time period.
Travis E. Huxman - One of the best experts on this subject based on the ideXlab platform.
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Volatile organic compound emissions from Larrea tridentata (creosotebush)
2010Co-Authors: Kolby J. Jardine, Leif Abrell, Shirley A. Kurc, Travis E. Huxman, John OrtegaAbstract:Abstract. We present results from the CREosote ATmosphere Interactions through Volatile Emissions (CREATIVE 2009) field study in southern Arizona aimed at quantifying emission rates of VOCs from creosotebush (Larrea tridentata) during the summer 2009 monsoon season. This species was chosen because of its vast distribution in North and South American deserts and because its resins have been reported to contain a rich set of volatile organic compounds (VOC). While a variety of ecosystems have been investigated for VOC emissions, deserts remain essentially unstudied, partially because of their low biomass densities and water limitations. However, during the North American monsoon, a pronounced increase in rainfall from an extremely dry June ( 80 mm) occurs over large areas of the Sonoran desert in the southwestern United States and northwestern Mexico. We observed a strong diurnal pattern of branch emissions and ambient concentrations of an extensive suite of VOCs with maxima in early afternoon. These include VOCs typically observed in forest sites (oxygenated VOCs and volatile isoprenoids) as well as a large number of other compounds, some of which have not been previously described from any plant including 1-chloro-2-methoxy-benzene and isobutyronitrile. Although generally considered to be derived from anthropogenic sources, we observed emissions of aromatic compounds including benzene, and a broad range of phenolics. Dimethyl sulfide emissions from creosotebush were higher than reported from any previously studied plant suggesting that terrestrial ecosystems should be reconsidered as an important source of this climatically important gas. We also present direct, primary emission measurements of isoprene and its apparent oxidation products methyl vinyl ketone, methacrolein, and 3-methyl furan (the later three compounds are typically assumed to form from secondary reactions within the atmosphere), as well as a group of compounds considered to be fatty acid oxidation products. These results suggest that one important function of some VOCs in creosotebush is as an antioxidant. We also find that emissions of nitriles from creosotebush could represent a significant but previously unaccounted nitrogen loss from this arid ecosystem. Our results demonstrate the richness of creosotebush volatile emissions and highlight the need for further research into their atmospheric and ecological impacts.
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photosynthetic responses of mojave desert shrubs to free air co2 enrichment are greatest during wet years
2003Co-Authors: Elke Naumburg, Michael E. Loik, Travis E. Huxman, Therese N Charlet, David C Housman, Stanley D. SmithAbstract:It has been suggested that desert vegetation will show the strongest response to rising atmospheric carbon dioxide due to strong water limitations in these systems that may be ameliorated by both photosynthetic enhancements and reductions in stomatal conductance. Here, we report the long-term effect of 55 Pa atmospheric CO2 on photosynthesis and stomatal conductance for three Mojave Desert shrubs of differing leaf phenology (Ambrosia dumosa—drought-deciduous, Krameria erecta—winter-deciduous, Larrea tridentata—evergreen). The shrubs were growing in an undisturbed ecosystem fumigated using FACE technology and were measured over a four-year period that included both above and below-average precipitation. Daily integrated photosynthesis (Aday) was significantly enhanced by elevated CO2 for all three species, although Krameria erecta showed the greatest enhancements (63% vs. 32% for the other species) enhancements were constant throughout the entire measurement period. Only one species, Larrea tridentata, decreased stomatal conductance by 25–50% in response to elevated CO2, and then only at the onset of the summer dry season and following late summer convective precipitation. Similarly, reductions in the maximum carboxylation rate of Rubisco were limited to Larrea during spring. These results suggest that the elevated CO2 response of desert vegetation is a function of complex interactions between species functional types and prevailing environmental conditions. Elevated CO2 did not extend the active growing season into the summer dry season because of overall negligible stomatal conductance responses that did not result in significant water conservation. Overall, we expect the greatest response of desert vegetation during years with above-average precipitation when the active growing season is not limited to ∼2 months and, consequently, the effects of increased photosynthesis can accumulate over a biologically significant time period.
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photosynthetic responses of Larrea tridentata to a step increase in atmospheric co2at the nevada desert face facility
2000Co-Authors: Michael E. Loik, Travis E. Huxman, Robert S Nowak, Erik P Hamerlynck, Dean N Jordan, Stephen F Zitzer, James S Coleman, S Redar, Jeffrey R SeemannAbstract:Abstract Of all terrestrial ecosystems, the productivity of deserts has been suggested to be the most responsive to increasing atmospheric CO2. The extent to which this prediction holds will depend in part on plant responses to elevated CO2under the highly variable conditions characteristic of arid regions. The photosynthetic responses ofLarrea tridentata , an evergreen shrub, to a step-increase in atmospheric CO2(to 550 μmolmol−1) were examined in the field using Free-Air CO2Enrichment (FACE) under seasonally varying moisture conditions. Elevated CO2substantially increased net assimilation rate (Anet) in Larrea during both moist and dry periods of the potential growing season, while stomatal conductance (gs) did not differ between elevated and ambient CO2treatments. Seasonal and diurnal gas exchange dynamics in elevated CO2mirrored patterns in ambient CO2, indicating that elevated CO2did not extend photosynthetic activity longer into the dry season or during more stressful times of the day. Net assimilation vs. internal CO2(A/Ci) responses showed no evidence of photosynthetic down-regulation during the dry season. In contrast, after significant autumn rains, Amax(the CO2saturated rate of photosynthesis) and CE (carboxylation efficiency) were lower in Larrea under elevated CO2. In situ chlorophyll fluorescence estimation ofLarrea Photosystem II efficiency (Fv/Fm) responded more to water limitation than to elevated CO2. These findings suggest that predictions regarding desert plant responses to elevated CO2should account for seasonal patterns of photosynthetic regulatory responses, which may vary across species and plant functional types.
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photosynthetic responses of Larrea tridentata to a step increase in atmospheric co2 at the nevada desert face facility
2000Co-Authors: Michael E. Loik, Travis E. Huxman, Robert S Nowak, Erik P Hamerlynck, Dean N Jordan, Stephen F Zitzer, James S Coleman, S Redar, Jeffrey R SeemannAbstract:Abstract Of all terrestrial ecosystems, the productivity of deserts has been suggested to be the most responsive to increasing atmospheric CO2. The extent to which this prediction holds will depend in part on plant responses to elevated CO2under the highly variable conditions characteristic of arid regions. The photosynthetic responses ofLarrea tridentata , an evergreen shrub, to a step-increase in atmospheric CO2(to 550 μmolmol−1) were examined in the field using Free-Air CO2Enrichment (FACE) under seasonally varying moisture conditions. Elevated CO2substantially increased net assimilation rate (Anet) in Larrea during both moist and dry periods of the potential growing season, while stomatal conductance (gs) did not differ between elevated and ambient CO2treatments. Seasonal and diurnal gas exchange dynamics in elevated CO2mirrored patterns in ambient CO2, indicating that elevated CO2did not extend photosynthetic activity longer into the dry season or during more stressful times of the day. Net assimilation vs. internal CO2(A/Ci) responses showed no evidence of photosynthetic down-regulation during the dry season. In contrast, after significant autumn rains, Amax(the CO2saturated rate of photosynthesis) and CE (carboxylation efficiency) were lower in Larrea under elevated CO2. In situ chlorophyll fluorescence estimation ofLarrea Photosystem II efficiency (Fv/Fm) responded more to water limitation than to elevated CO2. These findings suggest that predictions regarding desert plant responses to elevated CO2should account for seasonal patterns of photosynthetic regulatory responses, which may vary across species and plant functional types.
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photosynthetic down regulation in Larrea tridentata exposed to elevated atmospheric co2 interaction with drought under glasshouse and field face exposure
1998Co-Authors: Travis E. Huxman, Stanley D. Smith, Robert S Nowak, Erik P Hamerlynck, Brandon D Moore, Dean N Jordan, Stephen F Zitzer, James S Coleman, Jeffrey R SeemannAbstract:The photosynthetic response of Larrea tridentata Cav., an evergreen Mojave Desert shrub, to elevated atmospheric CO2 and drought was examined to assist in the understanding of how plants from water-limited ecosystems will respond to rising CO2. We hypothesized that photosynthetic down-regulation would disappear during periods of water limitation, and would, therefore, likely be a seasonally transient event. To test this we measured photosynthetic, water relations and fluorescence responses during periods of increased and decreased water availability in two different treatment implementations: (1) from seedlings exposed to 360, 550, and 700 μmol mol ‐1 CO2 in a glasshouse; and (2) from intact adults exposed to 360 and 550 μmol mol ‐1 CO2 at the Nevada Desert FACE (Free Air CO2 Enrichment) Facility. FACE and glasshouse well-watered Larrea significantly down-regulated photosynthesis at elevated CO 2, reducing maximum photosynthetic rate (Amax), carboxylation efficiency (CE), and Rubisco catalytic sites, whereas droughted Larrea showed a differing response depending on treatment technique. Amax and CE were lower in droughted Larrea compared with well-watered plants, and CO2 had no effect on these reduced photosynthetic parameters. However, Rubisco catalytic sites decreased in droughted Larrea at elevated CO2. Operating Ci increased at elevated CO2 in droughted plants, resulting in greater photosynthetic rates at elevated CO2 as compared with ambient CO2. In well-watered plants, the changes in operating Ci, CE and Amax resulted in similar photosynthetic rates across CO2 treatments. Our results suggest that drought can diminish photosynthetic down-regulation to elevated CO2 in Larrea, resulting in seasonally transient patterns of enhanced carbon gain. These results suggest that water status may ultimately control the photosynthetic response of desert systems to rising CO2.
Roberto Davicino - One of the best experts on this subject based on the ideXlab platform.
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Actividad antifungica de extractos de plantas usadas en medicina popular en Argentina
2013Co-Authors: Roberto Davicino, María Aída Mattar, Yolanda Angelina Casali, Silvia Graciela Correa, Elisa Margarita Pettenati, Blas MicalizziAbstract:Los hongos pueden causar enfermedades en humanos, especialmente en pacientes inmunosuprimidos. En este estudio, extractos de 10 plantas utilizadas en medicina popular en Argentina fueron ensayadas para estudiar la actividad antifúngica in vitro contra 4 cepas de hongos. De todas las plantas testeadas, solo 4 mostraron actividad antifúngica: Larrea divaricata Cav, Gnaphalium gaudichaudianum D.C, Baccharis trimera Less y Schinus terebenthifolius
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in vivo immunomodulatory effects of aqueous extracts of Larrea divaricata cav
2007Co-Authors: Roberto Davicino, Aida Mattar, Yolanda Casali, Carina Porporatto, Silvia G Correa, Blas MicalizziAbstract:Several medicinal plants are considered immunomodulatory as they display a variety of anti-inflammatory, antimicrobial and antitumoral effects. Larrea divaricata Cav. (jarilla) (Zygophyllaceae) is a plant widely used in popular medicine to treat tumors, infections, and inflammatory diseases. So far, the immunostimulating activities of Larrea divaricata have not been studied in vivo. In this work, we used healthy mice to assess the immunomodulatory potential of aqueous extracts of Larrea divaricata Cav. We found that Decoction (D) and Infusion (I) from Larrea divaricata Cav showed any acute hepatotoxic activity. Only D at 0.5 mg/kg increased the carrageenan-induced inflammation. Macrophages harvested from treated mice showed no signs of apoptosis. These cells showed a significant increase in NO and TNF-alpha release and exhibited the strongest expression of iNOS. Decoction also increased the phagocytosis of zymosan and the binding of LPS-FITC. The expression of CD14, TLR4 and CR3 was lower in macrophages of mice treated than in controls. Thus, Larrea divaricata was able to prime Mphi in vivo and to induce full activation in vitro. Our finding contribute to characterize the biological activity of Larrea divaricata and to understand the ability of these extracts to enhance immune responses.
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antimicrobial activity of aqueous extracts of Larrea divaricata cav jarilla against helicobacter pylori
2006Co-Authors: Patricia W Stege, Roberto Davicino, Yolanda Casali, Silvia G Correa, A E Vega, Blas MicalizziAbstract:We studied here the effect of aqueous extracts of Larrea divaricata Cav on the growth of Helicobacter pylori. Results show that cold extract, infusion, decoction and simulated digestion had inhibitory activity at 0.04-0.1 mg/l against clarithromycin and metronidazole susceptible and resistant H. pylori strains. These results support the popular use of L. divaricata Cav in gastric disturbances and prompt further research to characterize these compounds with a therapeutic potential against gastric ulcers and gastric cancer associated with H. pylori.
