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Sample records for ventilatory co2 response

  1. Response time and sensitivity of the ventilatory response to CO2 in unanesthetized intact dogs: central vs. peripheral chemoreceptors.

    Science.gov (United States)

    Smith, C A; Rodman, J R; Chenuel, B J A; Henderson, K S; Dempsey, J A

    2006-01-01

    We assessed the speed of the ventilatory response to square-wave changes in alveolar P(CO2) and the relative gains of the steady-state ventilatory response to CO2 of the central chemoreceptors vs. the carotid body chemoreceptors in intact, unanesthetized dogs. We used extracorporeal perfusion of the reversibly isolated carotid sinus to maintain normal tonic activity of the carotid body chemoreceptor while preventing it from sensing systemic changes in CO2, thereby allowing us to determine the response of the central chemoreceptors alone. We found the following. 1) The ventilatory response of the central chemoreceptors alone is 11.2 (SD = 3.6) s slower than when carotid bodies are allowed to sense CO2 changes. 2) On average, the central chemoreceptors contribute approximately 63% of the gain to steady-state increases in CO2. There was wide dog-to-dog variability in the relative contributions of central vs. carotid body chemoreceptors; the central exceeded the carotid body gain in four of six dogs, but in two dogs carotid body gain exceeded central CO2 gain. If humans respond similarly to dogs, we propose that the slower response of the central chemoreceptors vs. the carotid chemoreceptors prevents the central chemoreceptors from contributing significantly to ventilatory responses to rapid, transient changes in arterial P(CO2) such as those after periods of hypoventilation or hyperventilation ("ventilatory undershoots or overshoots") observed during sleep-disordered breathing. However, the greater average responsiveness of the central chemoreceptors to brain hypercapnia in the steady-state suggests that these receptors may contribute significantly to ventilatory overshoots once unstable/periodic breathing is fully established.

  2. Contributions of central and peripheral chemoreceptors to the ventilatory response to CO2/H+.

    Science.gov (United States)

    Forster, H V; Smith, C A

    2010-04-01

    The major objective of this review is to evaluate existing information and reach conclusions regarding whether there is interaction between P(CO(2))/H(+) stimulation of carotid (peripheral) and intracranial (central) chemoreceptors. Interaction is defined as a ventilatory response to simultaneous changes in the degree of Pco2/H(+) stimulation of both chemoreceptors that is greater (hyperadditive) or less (hypoadditive) than the sum of the responses when stimulation of each set of chemoreceptors is individually altered. Simple summation of the simultaneous changes in stimuli results in no interaction (i.e., additive interaction). Knowledge of the nature of central/peripheral interaction is crucial for determining the physiological significance of newer models of ventilatory control based on recent neuroanatomic observations of the circuitry of key elements of the ventilatory control system. In this review, we will propose that these two sets of receptors are not functionally separate but rather that they are dependent on one another such that the sensitivity of the medullary chemoreceptors is critically determined by input from the peripheral chemoreceptors and possibly other breathing-related reflex afferents as well. The short format of this minireview demands that we be somewhat selective in developing our ideas. We will briefly discuss the limitations of experiments used to study CO(2)/H(+) sensitivity and interaction to date, traditional views of the relative contributions of peripheral and central chemoreceptors to CO(2)/H(+) sensitivity, the evidence for and against different types of interaction, and the effect of tonic carotid chemoreceptor afferent activity on central control mechanisms.

  3. Orexinergic system in the locus coeruleus modulates the CO2 ventilatory response.

    Science.gov (United States)

    Vicente, Mariane C; Dias, Mirela B; Fonseca, Elisa M; Bícego, Kênia C; Gargaglioni, Luciane H

    2016-05-01

    The orexins are hypothalamic neuropeptides involved in an array of functions such as regulation of sleep/wake states and chemoreception to CO2/pH. The locus coeruleus (LC) is a chemosensitive site and expresses an extensive population of orexin receptor 1 (OX1R). We tested the hypothesis that OX1Rs located in the LC participate in the ventilatory response to hypercapnia in a vigilance state and diurnal cycle-dependent manner. For this, we performed unilateral injections of SB-334867 (OX1R antagonist, 5 mM) into the LC of male Wistar rats and evaluated the ventilatory response to 7 % CO2 during wakefulness and sleep in the dark and light phases of the diurnal cycle. Hypercapnia induced an increase in ventilation (V E) in all groups compared to normocapnic values. However, during the dark phase, but not in the light phase, SB-334867 injection promoted an attenuation of the hypercapnic chemoreflex during wakefulness (V E: vehicle, 1502.6 ± 100 mL kg(-1) min(-1) vs SB-334867, 1200.3 ± 70.0 mL kg(-1) min(-1)) but not during sleep (V E: vehicle, 1383.0 ± 113.9 vs SB-334687, 1287.6 ± 92.1 mL kg(-1) min(-1)), due to changes in tidal volume (V T). We suggest that projections of orexin-containing neurons to the LC contribute, via OX1Rs, to the hypercapnic chemoreflex during wakefulness in the dark phase.

  4. Contributions of central and peripheral chemoreceptors to the ventilatory response to CO2/H+

    OpenAIRE

    Forster, H. V.; Smith, C A

    2010-01-01

    The major objective of this review is to evaluate existing information and reach conclusions regarding whether there is interaction between Pco2/H+ stimulation of carotid (peripheral) and intracranial (central) chemoreceptors. Interaction is defined as a ventilatory response to simultaneous changes in the degree of Pco2/H+ stimulation of both chemoreceptors that is greater (hyperadditive) or less (hypoadditive) than the sum of the responses when stimulation of each set of chemoreceptors is in...

  5. Metabolic acidosis and ventilatory response

    NARCIS (Netherlands)

    Langbroek, Aart Jan Mattheüs

    1988-01-01

    In terrestrial vertebrates lung ventilation is nescessary to accmplish exchange of oxygen (O2) and carbon dioxide (CO2) between the gas phase (lung alveoli) and the fluid phase (the blood flowing through the lung capillaries). The ventilatory control system adjusts the arterial carbon dioxide

  6. Fluoxetine augments ventilatory CO2 sensitivity in Brown Norway but not Sprague Dawley rats

    Science.gov (United States)

    Hodges, Matthew R.; Echert, Ashley E.; Puissant, Madeleine M.; Mouradian, Gary C.

    2013-01-01

    The Brown Norway (BN; BN/NHsdMcwi) rat exhibits a deficit in ventilatory CO2 sensitivity and a modest serotonin (5-HT) deficiency. Here, we tested the hypothesis that the selective serotonin reuptake inhibitor fluoxetine would augment CO2 sensitivity in BN but not Sprague Dawley (SD) rats. Ventilation during room air or 7 % CO2 exposure was measured before, during and after 3 weeks of daily injections of saline or fluoxetine (10 mg/kg/day) in adult male BN and SD rats. Fluoxetine had minimal effects on room air breathing in BN and SD rats (p>0.05), although tidal volume (VT) was reduced in BN rats (pfluoxetine on CO2 sensitivity in SD rats, but fluoxetine increased minute ventilation, breathing frequency and VT during hypercapnia in BN rats (pfluoxetine. Brain levels of biogenic amines were largely unaffected, but 5-HIAA and the ratio of 5-HIAA/5-HT were reduced (pfluoxetine increases ventilatory CO2 sensitivity in BN but not SD rats, further suggesting altered 5-HT system function may contribute to the inherently low CO2 sensitivity in the BN rat. PMID:23454023

  7. Ventilatory responses to imagined exercise.

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    Gallego, J; Denot-Ledunois, S; Vardon, G; Perruchet, P

    1996-11-01

    We studied whether the ventilatory responses to imagined exercise are influenced by automatic processes. Twentynine athletes produced mental images of a sport event with successive focus on the environment, the preparation, and the exercise. Mean breathing frequency increased from 15 to 22 breaths/min. Five participants reported having voluntarily controlled breathing, two of them during preparation. Twenty participants reported that their breathing pattern changed during the experiment: 11 participants were unable to correctly report on the direction of changes in frequency, and 13 incorrectly reported changes in amplitude. This finding suggests that these changes were not voluntary in most participants and may therefore reveal automatic forebrain influences on exercise hyperpnea. However, these changes may also reflect nonspecific processes (e.g., arousal) different from those occurring during actual exercise.

  8. Chest vibration redistributes intra-airway CO2 during tracheal insufflation in ventilatory failure.

    Science.gov (United States)

    Eckmann, D M; Gavriely, N

    1996-03-01

    To determine if high-frequency external chest wall vibration added to low flow intratracheal fresh gas insufflation alters the intra-airway CO2 distribution and the resistance to CO2 transport from the lungs. Prospective study. Experimental laboratory. Six adult anesthesized and paralyzed mongrel dogs (mean weight 24.3+/- 4.4 kg). Dogs were ventilated by three methods: a) intermittent positive pressure ventilation; b) intermittent positive pressure ventilation with tracheal insufflation of fresh gas (FIO2 of 0.4) flowing at 0.15 L/kg/min through a catheter positioned at the carina; and c) intermittent positive pressure ventilation with tracheal insufflation and with external high-frequency chest wall vibration of the dependent hemithorax. We measured arterial blood gas values as an index of global gas exchange, and intrapulmonary airway CO2 concentrations as an index of local gas exchange. Intra-airway CO2 concentrations along the axis of the airways were measured via a sampling catheter. Airway axial concentration profiles were constructed and resistances to gas transport were calculated from the measured data. Vibration increased intraluminal CO2 concentrations from 1.1% to 2.5% mouthward of the insufflation catheter tip. Peak resistance to CO2 transport decreased by 65% during vibration relative to the insufflation-only value. Vibration displaced peak transport resistance from second- to fourth-generation airways. Global gas exchange improves during ventilation by chest wall vibration with low flow insufflation. Local gas exchange in the central airways is also improved due to increased intraluminal mixing and CO2 elimination. This ventilation technique may confer therapeutic advantages over conventional mechanical ventilation in the treatment of ventilatory failure.

  9. Adrenaline release evokes hyperpnoea and an increase in ventilatory CO2 sensitivity during hypoglycaemia: a role for the carotid body.

    Science.gov (United States)

    Thompson, Emma L; Ray, Clare J; Holmes, Andrew P; Pye, Richard L; Wyatt, Christopher N; Coney, Andrew M; Kumar, Prem

    2016-08-01

    Hypoglycaemia is counteracted by release of hormones and an increase in ventilation and CO2 sensitivity to restore blood glucose levels and prevent a fall in blood pH. The full counter-regulatory response and an appropriate increase in ventilation is dependent on carotid body stimulation. We show that the hypoglycaemia-induced increase in ventilation and CO2 sensitivity is abolished by preventing adrenaline release or blocking its receptors. Physiological levels of adrenaline mimicked the effect of hypoglycaemia on ventilation and CO2 sensitivity. These results suggest that adrenaline, rather than low glucose, is an adequate stimulus for the carotid body-mediated changes in ventilation and CO2 sensitivity during hypoglycaemia to prevent a serious acidosis in poorly controlled diabetes. Hypoglycaemia in vivo induces a counter-regulatory response that involves the release of hormones to restore blood glucose levels. Concomitantly, hypoglycaemia evokes a carotid body-mediated hyperpnoea that maintains arterial CO2 levels and prevents respiratory acidosis in the face of increased metabolism. It is unclear whether the carotid body is directly stimulated by low glucose or by a counter-regulatory hormone such as adrenaline. Minute ventilation was recorded during infusion of insulin-induced hypoglycaemia (8-17 mIU kg(-1)  min(-1) ) in Alfaxan-anaesthetised male Wistar rats. Hypoglycaemia significantly augmented minute ventilation (123 ± 4 to 143 ± 7 ml min(-1) ) and CO2 sensitivity (3.3 ± 0.3 to 4.4 ± 0.4 ml min(-1)  mmHg(-1) ). These effects were abolished by either β-adrenoreceptor blockade with propranolol or adrenalectomy. In this hypermetabolic, hypoglycaemic state, propranolol stimulated a rise in P aC O2, suggestive of a ventilation-metabolism mismatch. Infusion of adrenaline (1 μg kg(-1)  min(-1) ) increased minute ventilation (145 ± 4 to 173 ± 5 ml min(-1) ) without altering P aC O2 or pH and enhanced ventilatory CO2 sensitivity (3

  10. Ventilatory responses to hypercapnia and hypoxia after 6 h passive hyperventilation in humans

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    Ren, Xiaohui; Robbins, Peter A

    1999-01-01

    Acute exposure to hypoxia stimulates ventilation and induces hypocapnia. Long-term exposure to hypoxia generates changes in respiratory control known as ventilatory acclimatization to hypoxia. The object of this study was to investigate the degree to which the hyperventilation and hypocapnia can induce the changes known as ventilatory acclimatization to hypoxia, in the absence of the primary hypoxic stimulus itself.Three 6 h protocols were each performed on twelve healthy volunteers: (1) passive hypocapnic hyperventilation, with end-tidal CO2 pressure (PET,CO2) held 10 Torr below the eupnoeic value; (2) passive eucapnic hyperventilation, with PET,CO2 maintained eucapnic; (3) control.Ventilatory responses to acute hypercapnia and hypoxia were assessed before and half an hour after each protocol.The presence of prior hypocapnia, but not prior hyperventilation, caused a reduction in air-breathing PET,CO2 (P hyperventilation, but not prior hypocapnia, caused an increase in the ventilatory sensitivity to CO2 (P hyperventilation: (i) the left shift of the VE-PET,CO2 relationship is due to alkalosis and not to hyperventilation; (ii) the increase in slope of the VE-PET,CO2 relationship is due to the hyperventilation and not the alkalosis; and (iii) ventilatory sensitivity to hypoxia is unaltered. PMID:9882758

  11. Short-term modulation of the ventilatory response to exercise is preserved in obstructive sleep apnea.

    Science.gov (United States)

    Bernhardt, Vipa; Mitchell, Gordon S; Lee, Won Y; Babb, Tony G

    2017-02-01

    The ventilatory response to exercise can be transiently adjusted in response to environmentally (e.g., breathing apparatus) or physiologically altered conditions (e.g., respiratory disease), maintaining constant relative arterial PCO2 regulation from rest to exercise (Mitchell and Babb, 2006); this augmentation is called short-term modulation (STM) of the exercise ventilatory response. Obesity and/or obstructive sleep apnea could affect the exercise ventilatory response and the capacity for STM due to chronically increased mechanical and/or ventilatory loads on the respiratory system, and/or recurrent (chronic) intermittent hypoxia experienced during sleep. We hypothesized that: (1) the exercise ventilatory response is augmented in obese OSA patients compared with obese non-OSA adults, and (2) the capacity for STM with added dead space is diminished in obese OSA patients. Nine obese adults with OSA (age: 39±6 yr, BMI: 40±5kg/m(2), AHI: 25±24 events/h [range 6-73], mean±SD) and 8 obese adults without OSA (age: 38±10 yr, BMI: 37±6kg/m(2), AHI: 1±2) completed three, 20-min bouts of constant-load submaximal cycling exercise (8min rest, 6min at 10 and 30W) with or without added external dead space (200 or 400mL; 20min rest between bouts). Steady-state measurements were made of ventilation (V˙E), oxygen consumption V˙O2), carbon dioxide production (V˙CO2), and end-tidal PCO2 (PETCO2). The exercise ventilatory response was defined as the slope of the V˙E-V˙CO2 relationship (ΔV˙E/ΔV˙CO2). In control (i.e. no added dead space), the exercise ventilatory response was not significantly different between non-OSA and OSA groups (ΔV˙E/ΔV˙CO2 slope: 30.5±4.2 vs 30.5±3.8, p>0.05); PETCO2 regulation from rest to exercise did not differ between groups (p>0.05). In trials with added external dead space, ΔV˙E/ΔV˙CO2 increased with increased dead space (p exercise remained small (groups, demonstrating STM. There were no significant differences between groups

  12. Ventilatory Responses to Hypercapnia during Wakefulness and Sleep in Obese Adolescents With and Without Obstructive Sleep Apnea Syndrome

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    Yuan, Haibo; Pinto, Swaroop J.; Huang, Jingtao; McDonough, Joseph M.; Ward, Michelle B.; Lee, Yin N.; Bradford, Ruth M.; Gallagher, Paul R.; Shults, Justine; Konstantinopoulou, Sophia; Samuel, John M.; Katz, Eliot S.; Hua, Shucheng; Tapia, Ignacio E.; Marcus, Carole L.

    2012-01-01

    Study Objectives: Abnormal ventilatory drive may contribute to the pathophysiology of the childhood obstructive sleep apnea syndrome (OSAS). Concomitant with the obesity epidemic, more adolescents are developing OSAS. However, few studies have specifically evaluated the obese adolescent group. The authors hypothesized that obese adolescents with OSAS would have a blunted hypercapnic ventilatory response (HCVR) while awake and blunted ventilatory responses to carbon dioxide (CO2) during sleep compared with obese and lean adolescents without OSAS. Design: CVR was measured during wakefulness. During nonrapid eye movement (NREM) and rapid eye movement (REM) sleep, respiratory parameters and genioglossal electromyogram were measured during CO2 administration in comparison with room air in obese adolescents with OSAS, obese control study participants, and lean control study participants. Setting: Sleep laboratory. Participants: Twenty-eight obese patients with OSAS, 21 obese control study participants, and 37 lean control study participants. Results: The obese OSAS and obese control groups had a higher HCVR compared with the lean control group during wakefulness. During both sleep states, all 3 groups had a response to CO2; however, the obese OSAS group had lower percentage changes in minute ventilation, inspiratory flow, inspiratory time, and tidal volume compared with the 2 control groups. There were no significance differences in genioglossal activity between groups. Conclusions: HCVR during wakefulness is increased in obese adolescents. Obese adolescents with OSAS have blunted ventilatory responses to CO2 during sleep and do not have a compensatory prolongation of inspiratory time, despite having normal CO2 responsivity during wakefulness. Central drive may play a greater role than upper airway neuromotor tone in adapting to hypercapnia. Citation: Yuan H; Pinto SJ; Huang J; McDonough JM; Ward MB; Lee YN; Bradford RM; Gallagher PR; Shults J; Konstantinopoulou S

  13. Ventilatory functions response to breathing training versus aerobic ...

    African Journals Online (AJOL)

    EL-HAKIM

    Egypt J Pediatr Allergy Immunol 2012;10(1):33-37. 33. Ventilatory functions response to breathing training versus aerobic training in asthmatic children. INTRODUCTION ... as anxiety, light headedness, and fatigue4. Many previous ... Objective: To compare the effects of a program of breathing training and aerobic training ...

  14. Ventilatory responses to hypercapnia during wakefulness and sleep in obese adolescents with and without obstructive sleep apnea syndrome.

    Science.gov (United States)

    Yuan, Haibo; Pinto, Swaroop J; Huang, Jingtao; McDonough, Joseph M; Ward, Michelle B; Lee, Yin N; Bradford, Ruth M; Gallagher, Paul R; Shults, Justine; Konstantinopoulou, Sophia; Samuel, John M; Katz, Eliot S; Hua, Shucheng; Tapia, Ignacio E; Marcus, Carole L

    2012-09-01

    Abnormal ventilatory drive may contribute to the pathophysiology of the childhood obstructive sleep apnea syndrome (OSAS). Concomitant with the obesity epidemic, more adolescents are developing OSAS. However, few studies have specifically evaluated the obese adolescent group. The authors hypothesized that obese adolescents with OSAS would have a blunted hypercapnic ventilatory response (HCVR) while awake and blunted ventilatory responses to carbon dioxide (CO(2)) during sleep compared with obese and lean adolescents without OSAS. CVR was measured during wakefulness. During nonrapid eye movement (NREM) and rapid eye movement (REM) sleep, respiratory parameters and genioglossal electromyogram were measured during CO(2) administration in comparison with room air in obese adolescents with OSAS, obese control study participants, and lean control study participants. Sleep laboratory. Twenty-eight obese patients with OSAS, 21 obese control study participants, and 37 lean control study participants. The obese OSAS and obese control groups had a higher HCVR compared with the lean control group during wakefulness. During both sleep states, all 3 groups had a response to CO(2); however, the obese OSAS group had lower percentage changes in minute ventilation, inspiratory flow, inspiratory time, and tidal volume compared with the 2 control groups. There were no significance differences in genioglossal activity between groups. HCVR during wakefulness is increased in obese adolescents. Obese adolescents with OSAS have blunted ventilatory responses to CO(2) during sleep and do not have a compensatory prolongation of inspiratory time, despite having normal CO(2) responsivity during wakefulness. Central drive may play a greater role than upper airway neuromotor tone in adapting to hypercapnia.

  15. Adaptive support and pressure support ventilation behavior in response to increased ventilatory demand.

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    Jaber, Samir; Sebbane, Mustapha; Verzilli, Daniel; Matecki, Stefan; Wysocki, Marc; Eledjam, Jean-Jacques; Brochard, Laurent

    2009-03-01

    Dual-control modes of ventilation adapt the pressure delivery to keep a volume target in response to changes in respiratory mechanics, but they may respond poorly to changes in ventilatory demand. Adaptive support ventilation (ASV), a complex minute volume-targeted pressure-regulated ventilation, was compared to adaptive pressure ventilation (APV), a dual-mode in which the pressure level is adjusted to deliver a preset tidal volume, and to pressure support ventilation (PSV) when facing an increase in ventilatory demand. A total of 14 intensive care unit patients being weaned off mechanical ventilation were included in this randomized crossover study. The effect of adding a heat-and-moisture exchanger to augment circuit dead space was assessed with a same fixed level of ASV, PSV, and APV. Arterial blood gases, ventilator response, and patient respiratory effort parameters were evaluated at the end of the six periods. Adding dead space significantly increased minute ventilation and PaCO2 values with the three modes. Indexes of respiratory effort (pressure-time index of respiratory muscles and work of breathing) increased with all ventilatory modes after dead-space augmentation. This increase was significantly greater with APV than with PSV or ASV (P ventilator.

  16. Sensory Transduction of the CO2 Response of Guard Cells

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Eduardo Zeiger

    2003-06-30

    Stomata have a key role in the regulation of gas exchange and intercellular CO2 concentrations of leaves. Guard cells sense internal and external signals in the leaf environment and transduce these signals into osmoregulatory processes that control stomatal apertures. This research proposal addresses the characterization of the sensory transduction of the CO2 signal in guard cells. Recent studies have shown that in Vicia leaves kept at constant light and temperature in a growth chamber, changes in ambient CO2 concentrations cause large changes in guard cell zeaxanthin that are linear with CO2-dependent changes in stomatal apertures. Research proposed here will test the hypothesis that zeaxanthin function as a transducer of CO2 signals in guard cells. Three central aspects of this hypothesis will be investigated: CO2 sensing by the carboxylation reaction of Rubisco in the guard cell chloroplast, which would modulate zeaxanthin concentrations via changes in lumen pH; transduction of the CO2 signal by zeaxanthin via a transducing cascade that controls guard cell osmoregulation; and blue light dependence of the CO2 signal transduction by zeaxanthin, required for the formation of an isomeric form of zeaxanthin that is physiologically active as a transducer. The role of Rubisco in CO2 sensing will be investigated in experiments characterizing the stomatal response to CO2 in the Arabidopsis mutants R100 and rca-, which have reduced rates of Rubisco-dependent carboxylation. The role of zeaxanthin as a CO2 transducer will be studied in npq1, a zeaxanthin-less mutant. The blue light-dependence of CO2 sensing will be studied in experiments characterizing the stomatal response to CO2 under red light. Arabidopsis mutants will also be used in further studies of an acclimation of the stomatal response to CO2, and a possible role of the xanthophyll cycle of the guard cell chloroplast in acclimations of the stomatal response to CO2. Studies on the osmoregulatory role of sucrose in

  17. CO2-Responsive Polymer-Functionalized Au Nanoparticles for CO2 Sensor.

    Science.gov (United States)

    Ma, Ying; Promthaveepong, Kittithat; Li, Nan

    2016-08-16

    Metallic nanoparticles (NPs) coated with stimuli-responsive polymers (SRPs) exhibit tunable optical properties responding to external stimuli and show promising sensing applications. We present a new CO2-responsive polymer, poly(N-(3-amidino)-aniline) (PNAAN), coated gold NPs (AuNPs) synthesized by directly reducing HAuCl4 with a CO2-responsive monomer N-(3-amidino)-aniline (NAAN). The amidine group of PNAAN can be protonated into a hydrophilic amidinium group by dissolved CO2 (dCO2). This induces the PNAAN to swell and detach from the AuNP surface, resulting in AuNP aggregation and color change. By monitoring the UV absorbance change of AuNPs, a sensitive dCO2 sensor with a linear range of 0.0132 to 0.1584 hPa and a limit of detection (LOD) of 0.0024 hPa is developed. This method shows dramatic improvement in sensitivity and convenience of sample preparation compared with the previously reported dCO2 sensor.

  18. Behavioral, Ventilatory and Thermoregulatory Responses to Hypercapnia and Hypoxia in the Wistar Audiogenic Rat (WAR Strain.

    Directory of Open Access Journals (Sweden)

    Érica Maria Granjeiro

    Full Text Available We investigated the behavioral, respiratory, and thermoregulatory responses elicited by acute exposure to both hypercapnic and hypoxic environments in Wistar audiogenic rats (WARs. The WAR strain represents a genetic animal model of epilepsy.Behavioral analyses were performed using neuroethological methods, and flowcharts were constructed to illustrate behavioral findings. The body plethysmography method was used to obtain pulmonary ventilation (VE measurements, and body temperature (Tb measurements were taken via temperature sensors implanted in the abdominal cavities of the animals.No significant difference was observed between the WAR and Wistar control group with respect to the thermoregulatory response elicited by exposure to both acute hypercapnia and acute hypoxia (p>0.05. However, we found that the VE of WARs was attenuated relative to that of Wistar control animals during exposure to both hypercapnic (WAR: 133 ± 11% vs. Wistar: 243 ± 23%, p<0.01 and hypoxic conditions (WAR: 138 ± 8% vs. Wistar: 177 ± 8%; p<0.01. In addition, we noted that this ventilatory attenuation was followed by alterations in the behavioral responses of these animals.Our results indicate that WARs, a genetic model of epilepsy, have important alterations in their ability to compensate for changes in levels of various arterial blood gasses. WARs present an attenuated ventilatory response to an increased PaCO2 or decreased PaO2, coupled to behavioral changes, which make them a suitable model to further study respiratory risks associated to epilepsy.

  19. Increasing stomatal conductance in response to rising atmospheric CO2.

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    Purcell, C; Batke, S P; Yiotis, C; Caballero, R; Soh, W K; Murray, M; McElwain, J C

    2018-01-31

    Studies have indicated that plant stomatal conductance (gs) decreases in response to elevated atmospheric CO2, a phenomenon of significance for the global hydrological cycle. However, gs increases across certain CO2 ranges have been predicted by optimization models. The aim of this work was to demonstrate that under certain environmental conditions, gs can increase in response to elevated CO2. Using (1) an extensive, up-to-date synthesis of gs responses in free air CO2 enrichment (FACE)experiments, (2) in situ measurements across four biomes showing dynamic gs responses to a CO2 rise of ~50 ppm (characterizing the change in this greenhouse gas over the past three decades) and (3) a photosynthesis-stomatal conductance model, it is demonstrated that gs can in some cases increase in response to increasing atmospheric CO2. Field observations are corroborated by an extensive synthesis of gs responses in FACE experiments showing that 11.8 % of gs responses under experimentally elevated CO2 are positive. They are further supported by a strong data-model fit (r2 = 0.607) using a stomatal optimization model applied to the field gs dataset. A parameter space identified in the Farquhar-Ball-Berry photosynthesis-stomatal conductance model confirms field observations of increasing gs under elevated CO2 in hot dry conditions. Contrary to the general assumption, positive gs responses to elevated CO2, although relatively rare, are a feature of woody taxa adapted to warm, low-humidity conditions, and this response is also demonstrated in global simulations using the Community Land Model (CLM4). The results contradict the over-simplistic notion that global vegetation always responds with decreasing gs to elevated CO2, a finding that has important implications for predicting future vegetation feedbacks on the hydrological cycle at the regional level.

  20. Hemodynamic and ventilatory response to different levels of hypoxia and hypercapnia in carotid body-denervated rats

    Directory of Open Access Journals (Sweden)

    João Paulo J. Sabino

    2013-01-01

    Full Text Available OBJECTIVE: Chemoreceptors play an important role in the autonomic modulation of circulatory and ventilatory responses to changes in arterial O2 and/or CO2. However, studies evaluating hemodynamic responses to hypoxia and hypercapnia in rats have shown inconsistent results. Our aim was to evaluate hemodynamic and respiratory responses to different levels of hypoxia and hypercapnia in conscious intact or carotid body-denervated rats. METHODS: Male Wistar rats were submitted to bilateral ligature of carotid body arteries (or sham-operation and received catheters into the left femoral artery and vein. After two days, each animal was placed into a plethysmographic chamber and, after baseline measurements of respiratory parameters and arterial pressure, each animal was subjected to three levels of hypoxia (15, 10 and 6% O2 and hypercapnia (10% CO2. RESULTS: The results indicated that 15% O2 decreased the mean arterial pressure and increased the heart rate (HR in both intact (n = 8 and carotid body-denervated (n = 7 rats. In contrast, 10% O2did not change the mean arterial pressure but still increased the HR in intact rats, and it decreased the mean arterial pressure and increased the heart rate in carotid body-denervated rats. Furthermore, 6% O2 increased the mean arterial pressure and decreased the HR in intact rats, but it decreased the mean arterial pressure and did not change the HR in carotid body-denervated rats. The 3 levels of hypoxia increased pulmonary ventilation in both groups, with attenuated responses in carotid body-denervated rats. Hypercapnia with 10% CO2 increased the mean arterial pressure and decreased HR similarly in both groups. Hypercapnia also increased pulmonary ventilation in both groups to the same extent. CONCLUSION: This study demonstrates that the hemodynamic and ventilatory responses varied according to the level of hypoxia. Nevertheless, the hemodynamic and ventilatory responses to hypercapnia did not depend on the

  1. Responses of soil CO2 efflux to changes in plant CO2 uptake and transpiration

    Science.gov (United States)

    Balogh, János; de Luca, Giulia; Mészáros, Ádám; Trieber, Júlia; Gecse, Bernadett; Fóti, Szilvia; Pintér, Krisztina; Nagy, Zoltán

    2017-04-01

    results, the effect of the assimilated CO2 appeared after 3 hours in soil CO2 efflux. The lack of light (24 hours) caused 20% decrease in total soil CO2 efflux. The decrease of the plant transpiration rate slightly increased the autotrophic component. These responses could be useful in clarifying the drivers behind the diel variability of soil respiration.

  2. Varied growth response of cogongrass ecotypes to elevated CO2

    Directory of Open Access Journals (Sweden)

    G. Brett Runion

    2016-01-01

    Full Text Available Cogongrass [Imperata cylindrica (L. P. Beauv] is an invasive C4 perennial grass which is listed as one of the top ten worst weeds in the world and is a major problem in the Southeast US. Five cogongrass ecotypes (Florida, Hybrid, Louisiana, Mobile, and North Alabama collected across the Southeast and a red-tip ornamental variety were container grown for six months in open top chambers under ambient and elevated (ambient plus 200 ppm atmospheric CO2. Elevated CO2 increased average dry weight (13% which is typical for grasses. Elevated CO2 increased height growth and both nitrogen and water use efficiencies, but lowered tissue nitrogen concentration; again, these are typical plant responses to elevated CO2. The hybrid ecotype tended to exhibit the greatest growth (followed by Louisiana, North Alabama, and Florida ecotypes while the red-tip and Mobile ecotypes were smallest. Interactions of CO2 with ecotype generally showed that the hybrid, Louisiana, Florida, and/or North Alabama ecotypes showed a positive response to CO2 while the Mobile and red-tip ecotypes did not. Cogongrass is a problematic invasive weed in the southeastern U.S. and some ecotypes may become more so as atmospheric CO2 continues to rise.

  3. Identification of a CO2 responsive regulon in Bordetella.

    Science.gov (United States)

    Hester, Sara E; Lui, Minghsun; Nicholson, Tracy; Nowacki, Daryl; Harvill, Eric T

    2012-01-01

    Sensing the environment allows pathogenic bacteria to coordinately regulate gene expression to maximize survival within or outside of a host. Here we show that Bordetella species regulate virulence factor expression in response to carbon dioxide levels that mimic in vivo conditions within the respiratory tract. We found strains of Bordetella bronchiseptica that did not produce adenylate cyclase toxin (ACT) when grown in liquid or solid media with ambient air aeration, but produced ACT and additional antigens when grown in air supplemented to 5% CO(2). Transcriptome analysis and quantitative real time-PCR analysis revealed that strain 761, as well as strain RB50, increased transcription of genes encoding ACT, filamentous hemagglutinin (FHA), pertactin, fimbriae and the type III secretion system in 5% CO(2) conditions, relative to ambient air. Furthermore, transcription of cyaA and fhaB in response to 5% CO(2) was increased even in the absence of BvgS. In vitro analysis also revealed increases in cytotoxicity and adherence when strains were grown in 5% CO(2). The human pathogens B. pertussis and B. parapertussis also increased transcription of several virulence factors when grown in 5% CO(2), indicating that this response is conserved among the classical bordetellae. Together, our data indicate that Bordetella species can sense and respond to physiologically relevant changes in CO(2) concentrations by regulating virulence factors important for colonization, persistence and evasion of the host immune response.

  4. Identification of a CO2 responsive regulon in Bordetella.

    Directory of Open Access Journals (Sweden)

    Sara E Hester

    Full Text Available Sensing the environment allows pathogenic bacteria to coordinately regulate gene expression to maximize survival within or outside of a host. Here we show that Bordetella species regulate virulence factor expression in response to carbon dioxide levels that mimic in vivo conditions within the respiratory tract. We found strains of Bordetella bronchiseptica that did not produce adenylate cyclase toxin (ACT when grown in liquid or solid media with ambient air aeration, but produced ACT and additional antigens when grown in air supplemented to 5% CO(2. Transcriptome analysis and quantitative real time-PCR analysis revealed that strain 761, as well as strain RB50, increased transcription of genes encoding ACT, filamentous hemagglutinin (FHA, pertactin, fimbriae and the type III secretion system in 5% CO(2 conditions, relative to ambient air. Furthermore, transcription of cyaA and fhaB in response to 5% CO(2 was increased even in the absence of BvgS. In vitro analysis also revealed increases in cytotoxicity and adherence when strains were grown in 5% CO(2. The human pathogens B. pertussis and B. parapertussis also increased transcription of several virulence factors when grown in 5% CO(2, indicating that this response is conserved among the classical bordetellae. Together, our data indicate that Bordetella species can sense and respond to physiologically relevant changes in CO(2 concentrations by regulating virulence factors important for colonization, persistence and evasion of the host immune response.

  5. Ventilatory response to progressive curarization in patients during light halothane, N2O in O2 anaesthesia.

    Science.gov (United States)

    Linko, K; Wirtavuori, K; Tammisto, T

    1984-06-01

    The effects of progressive curarization on spontaneous ventilation were studied in 23 patients during light halothane-nitrous oxide-oxygen anaesthesia. In 11 patients, in whom the end-expiratory CO2 concentration and evoked mechanical response were recorded, increasing curarization caused first a slow CO2 accumulation and later an abrupt ventilatory impairment at a twitch tension of between 5 and 50% of original muscle strength. In 12 patients, in whom the evoked integrated hypothenar EMG, spontaneous frontal EMG and mean frequency and amplitude of the EEG were recorded, the spontaneous frontal EMG and ventilation diminished within 3 min, following the first 5 mg dose of tubocurarine. At this stage muscle strength, indicated by the amplitude of the evoked EMG and the train-of-four ratio, was unchanged. Repeated 5 mg doses of tubocurarine caused an almost linear decrease in ventilation and an increase in end-tidal CO2 concentration without affecting the rate of breathing until the sudden impairment of ventilation that occurred usually after the fourth dose of tubocurarine. The EEG changes during curarization were minimal and no common trend was seen. The results suggest that tubocurarine may be given to anaesthetized patients in a dose which is too small to produce, using the evoked EMG, a detectable neuromuscular block, but is sufficient to cause ventilatory depression without a compensatory increase in the rate of breathing.

  6. Polycythemia and high levels of erythropoietin in blood and brain blunt the hypercapnic ventilatory response in adult mice.

    Science.gov (United States)

    Menuet, Clément; Khemiri, Hanan; de la Poëze d'Harambure, Théodora; Gestreau, Christian

    2016-05-15

    Changes in arterial Po2, Pco2, and pH are the strongest stimuli sensed by peripheral and central chemoreceptors to adjust ventilation to the metabolic demand. Erythropoietin (Epo), the main regulator of red blood cell production, increases the hypoxic ventilatory response, an effect attributed to the presence of Epo receptors in both carotid bodies and key brainstem structures involved in integration of peripheral inputs and control of breathing. However, it is not known whether Epo also has an effect on the hypercapnic chemoreflex. In a first attempt to answer this question, we tested the hypothesis that Epo alters the ventilatory response to increased CO2 levels. Basal ventilation and hypercapnic ventilatory response (HCVR) were recorded from control mice and from two transgenic mouse lines constitutively expressing high levels of human Epo in brain only (Tg21) or in brain and plasma (Tg6), the latter leading to polycythemia. To tease apart the potential effects of polycythemia and levels of plasma Epo in the HCVR, control animals were injected with an Epo analog (Aranesp), and Tg6 mice were treated with the hemolytic agent phenylhydrazine after splenectomy. Ventilatory parameters measured by plethysmography in conscious mice were consistent with data from electrophysiological recordings in anesthetized animals and revealed a blunted HCVR in Tg6 mice. Polycythemia alone and increased levels of plasma Epo blunt the HCVR. In addition, Tg21 mice with an augmented level of cerebral Epo also had a decreased HCVR. We discuss the potential implications of these findings in several physiopathological conditions. Copyright © 2016 the American Physiological Society.

  7. CO2-induced photosynthetic and stoichiometric responses to phosphorus limitation

    Science.gov (United States)

    de Boer, Hugo; di Lallo, Giacomo; van Dijk, Jerry

    2017-04-01

    Carbon fertilisation from rising atmospheric CO2 concentrations increases the productivity of plants globally. Meanwhile, the global cycles of Nitrogen (N) and Phosphorus (P) are also altered due to anthropogenic emissions. In general, the additional supply of N is expected to exceed that of P, leading to an increase in P limitation in natural ecosystems. Although the direct carbon fertilisation effect and the interaction with available N is relatively well understood, it remains uncertain how carbon fertilisation is confounded by the availability of P. It is hypothesised that (i) the photosynthetic P-use efficiency increases at elevated CO2 owing to a direct increase in photosynthesis and (ii) the photosynthetic maximum carboxylation rate (Vcmax) and electron transport rate (Jmax) are down-regulated in response to a combination of elevated CO2 and P-limitation via a coordinated reduction of leaf N and P content per unit leaf area. In this study we examined the hypothesised effects of P limitation and CO2 fertilisation on the photosynthetic and stoichiometric responses of three plant species: Holcus lanatus (C3 grass), Panicum miliaceum (C4 grass) and Solanum dulcamara (C3 herb). Individuals of these species were grown at sub-ambient (150 ppm), modern (450 ppm) and elevated CO2 concentrations (800 ppm) and exposed to an N:P treatment consisting of either severe nitrogen limitation at an N:P ratio of 1:1, or severe P limitation at an N:P ratio of 45:1, with a similar supply rate of N. Our results show significant effects of growth CO2 and P supply on Vcmax and Jmax, as well as the whole-plant biomass at the point of harvest. Interaction effects between growth CO2 and P supply were observed for the light-saturated photosynthesis rate, stomatal conductance, leaf P content, and the N:P ratio of the leaf. No significant change in the leaf N content was observed across treatments. These results suggest that limited availability of P constrains the biochemical potential

  8. Stomatal Responses to CO2 in Paphiopedilum and Phragmipedium1

    Science.gov (United States)

    Assmann, Sarah M.; Zeiger, Eduardo

    1985-01-01

    A role of the guard cell chloroplasts in the CO2 response of stomata was investigated through a comparison of the leaf gas exchange characteristics of two closely related orchids: Paphiopedilum harrisianum, which lacks guard cell chloroplasts and Phragmipedium longifolium, which has chlorophyllous guard cells. Leaves of both species had an apparent quantum yield for assimilation of about 0.05, with photosynthesis saturating at 0.300 to 0.400 millimoles per square meter per second. CO2 curves were obtained by measuring steady-state assimilation and stomatal conductance under 0.180 or 0.053 millimoles per square meter per second white light, or darkness, at 0 to 400 microliters per liter ambient CO2. The response of assimilation to changes in CO2 was similar in the two species, but the response of conductance was consistently weaker in Paphiopedilum than in Phragmipedium. The data suggest involvement of guard cell chloroplasts in the stomatal response to CO2 and in the coupling of assimilation and conductance in the intact leaf. PMID:16664075

  9. Ventilatory functions response to breathing training versus aerobic ...

    African Journals Online (AJOL)

    Background: There is worldwide public interest in physical therapies for asthma. Objective: To compare the effects of a program of breathing training and aerobic training on ventilatory functions in children with bronchial asthma. Methods: Forty asthmatic children from both genders (22 boys and 18 girls) were recruited to ...

  10. Influence of menstrual phase on ventilatory response to submaximal ...

    African Journals Online (AJOL)

    Objectives. To determine whether an increase in respiratory drive, due to elevated progesterone and oestrogen concentration during various menstrual phases, persists throughout prolonged submaximal exercise and potentially contributes to fatigue. Furthermore, to determine whether the difference in the ventilatory ...

  11. Increased ventilatory response to carbon dioxide in COPD patients following vitamin C administration

    Directory of Open Access Journals (Sweden)

    Sara E. Hartmann

    2015-09-01

    Full Text Available Patients with chronic obstructive pulmonary disease (COPD have decreased ventilatory and cerebrovascular responses to hypercapnia. Antioxidants increase the ventilatory response to hypercapnia in healthy humans. Cerebral blood flow is an important determinant of carbon dioxide/hydrogen ion concentration at the central chemoreceptors and may be affected by antioxidants. It is unknown whether antioxidants can improve the ventilatory and cerebral blood flow response in individuals in whom these are diminished. Thus, we aimed to determine the effect of vitamin C administration on the ventilatory and cerebrovascular responses to hypercapnia during healthy ageing and in COPD. Using transcranial Doppler ultrasound, we measured the ventilatory and cerebral blood flow responses to hyperoxic hypercapnia before and after an intravenous vitamin C infusion in healthy young (Younger and older (Older subjects and in moderate COPD. Vitamin C increased the ventilatory response in COPD patients (mean (95% CI 1.1 (0.9–1.1 versus 1.5 (1.1–2.0 L·min−1·mmHg−1, p0.05 or Older (1.3 (1.0–1.7 versus 1.3 (1.0–1.7 L·min−1·mmHg−1, p>0.05 healthy subjects. Vitamin C did not affect the cerebral blood flow response in the young or older healthy subjects or COPD subjects (p>0.05. Vitamin C increases the ventilatory but not cerebrovascular response to hyperoxic hypercapnia in patients with moderate COPD.

  12. Elevated [CO2] modified the drought acclimation response in peanut

    Science.gov (United States)

    Peanut agroecosystems play a key role in food production and are a major source of protein in many arid and semi-arid regions where extreme weather events are expected to increase in frequency. We are taking a systems-level approach to investigate the response of peanut to elevated [CO2], water defi...

  13. Coccolithophore Response to CO2 Increase and Related Ecological Changes

    Science.gov (United States)

    Ziveri, P.

    2007-12-01

    Changes in ocean chemistry due to anthropogenic CO2 emissions affect marine life, nutrient cycles and biocalcification. Ocean acidification has been identified as a major consequence of rising atmospheric CO2 levels. This makes understanding the response of calcareous plankton, and other effects of global change, an urgent challenge. There have been controversial results from culture experiments and field observations, on the impact of CO2 increase on coccolithophore calcification and ecology. The objective of this presentation is to report the state-of-the-art on the impact of ocean acidification on coccolithophores and possible consequences on their biogeography and ecology. Results will also be reported from a workshop sponsored by the European Science Foundation (Euroclimate Program) and PAGES on Atmopheric CO2, ocean acidification and ecological changes in planktonic calcifying organisms. A wide range of experts contributed to that workshop, from the cellular and genetic to the ecological and global carbon cycle levels. Questions include how the predicted CO2 increase and acidification is likely to affect coccolithophores, what the possible secondary consequences may be, and what research is needed to allow robust predictions for the future.

  14. Chemosensitivity, Cardiovascular Risk, and the Ventilatory Response to Exercise in COPD.

    Science.gov (United States)

    Stickland, Michael K; Fuhr, Desi P; Edgell, Heather; Byers, Brad W; Bhutani, Mohit; Wong, Eric Y L; Steinback, Craig D

    2016-01-01

    COPD is associated with elevated cardiovascular risk and a potentiated ventilatory response to exercise. Enhanced carotid chemoreceptor (CC) activity/sensitivity is present in other clinical conditions, has been shown to contribute to sympathetic vasoconstrictor outflow, and is predictive of mortality. CC activity/sensitivity, and the resulting functional significance, has not been well examined in COPD. We hypothesized that CC activity/sensitivity would be elevated in COPD, and related to increased pulse wave velocity (a marker of CV risk) and the ventilatory response to exercise. 30 COPD patients and 10 healthy age-matched controls were examined. Participants performed baseline cardiopulmonary exercise and pulmonary function testing. CC activity was later evaluated by the drop in ventilation with breathing 100% O2, and CC sensitivity was then assessed by the ventilatory response to hypoxia (ΔVE/ΔSpO2). Peripheral arterial stiffness was subsequently evaluated by measurement of pulse wave velocity (PWV) using applanation tonometry while the subjects were breathing room air, and then following chemoreceptor inhibition by breathing 100% O2 for 2 minutes. CC activity, CC sensitivity, PWV and the ventilatory response to exercise were all increased in COPD relative to controls. CC sensitivity was related to PWV; however, neither CC activity nor CC sensitivity was related to the ventilatory response to exercise in COPD. CC inhibition by breathing 100% O2 normalized PWV in COPD, while no effect was observed in controls. CC activity and sensitivity are elevated in COPD, and appear related to cardiovascular risk; however, CC activity/sensitivity does not contribute to the potentiated ventilatory response to exercise.

  15. Photosynthetic responses to elevated CO(2) and O(3) in Quercus ilex leaves at a natural CO(2) spring.

    Science.gov (United States)

    Paoletti, E; Seufert, G; Della Rocca, G; Thomsen, H

    2007-06-01

    Photosynthetic stimulation and stomatal conductance (Gs) depression in Quercus ilex leaves at a CO(2) spring suggested no down-regulation. The insensitivity of Gs to a CO(2) increase (from ambient 1500 to 2000 micromol mol(-1)) suggested stomatal acclimation. Both responses are likely adaptations to the special environment of CO(2) springs. At the CO(2)-enriched site, not at the control site, photosynthesis decreased 9% in leaves exposed to 2x ambient O(3) concentrations in branch enclosures, compared to controls in charcoal-filtered air. The stomatal density reduction at high CO(2) was one-third lower than the concomitant Gs reduction, so that the O(3) uptake per single stoma was lower than at ambient CO(2). No significant variation in monoterpene emission was measured. Higher trichome and mesophyll density were recorded at the CO(2)-enriched site, accounting for lower O(3) sensitivity. A long-term exposure to H(2)S, reflected by higher foliar S-content, and CO(2) might depress the antioxidant capacity of leaves close to the vent and increase their O(3) sensitivity.

  16. Impaired Ventilatory and Thermoregulatory Responses to Hypoxic Stress in Newborn Phox2b Heterozygous Knock-Out Mice

    Science.gov (United States)

    Ramanantsoa, Nelina; Matrot, Boris; Vardon, Guy; Lajard, Anne-Marie; Voituron, Nicolas; Dauger, Stéphane; Denjean, André; Hilaire, Gérard; Gallego, Jorge

    2011-01-01

    The Phox2b genesis necessary for the development of the autonomic nervous system, and especially, of respiratory neuronal circuits. In the present study, we examined the role of Phox2b in ventilatory and thermoregulatory responses to hypoxic stress, which are closely related in the postnatal period. Hypoxic stress was generated by strong thermal stimulus, combined or not with reduced inspired O2. To this end, we exposed 6-day-old Phox2b+/− pups and their wild-type littermates (Phox2b+/+) to hypoxia (10% O2) or hypercapnia (8% CO2) under thermoneutral (33°C) or cold (26°C) conditions. We found that Phox2b+/− pups showed less normoxic ventilation (VE) in the cold than Phox2b+/+ pups. Phox2b+/− pups also showed lower oxygen consumption (VO2) in the cold, reflecting reduced thermogenesis and a lower body temperature. Furthermore, while the cold depressed ventilatory responses to hypoxia and hypercapnia in both genotype groups, this effect was less pronounced in Phox2b+/− pups. Finally, because serotonin (5-HT) neurons are pivotal to respiratory and thermoregulatory circuits and depend on Phox2b for their differentiation, we studied 5-HT metabolism using high pressure liquid chromatography, and found that it was altered in Phox2b+/− pups. We conclude that Phox2b haploinsufficiency alters the ability of newborns to cope with metabolic challenges, possibly due to 5-HT signaling impairments. PMID:21977017

  17. Responses of pink salmon to CO2-induced aquatic acidification

    Science.gov (United States)

    Ou, Michelle; Hamilton, Trevor J.; Eom, Junho; Lyall, Emily M.; Gallup, Joshua; Jiang, Amy; Lee, Jason; Close, David A.; Yun, Sang-Seon; Brauner, Colin J.

    2015-10-01

    Ocean acidification negatively affects many marine species and is predicted to cause widespread changes to marine ecosystems. Similarly, freshwater ecosystems may potentially be affected by climate-change-related acidification; however, this has received far less attention. Freshwater fish represent 40% of all fishes, and salmon, which rear and spawn in freshwater, are of immense ecosystem, economical and cultural importance. In this study, we investigate the impacts of CO2-induced acidification during the development of pink salmon, in freshwater and following early seawater entry. At this critical and sensitive life stage, we show dose-dependent reductions in growth, yolk-to-tissue conversion and maximal O2 uptake capacity; as well as significant alterations in olfactory responses, anti-predator behaviour and anxiety under projected future increases in CO2 levels. These data indicate that future populations of pink salmon may be at risk without mitigation and highlight the need for further studies on the impact of CO2-induced acidification on freshwater systems.

  18. Assumption Centred Modelling of Ecosystem Responses to CO2 at Six US Atmospheric CO2 Enrichment Experiments.

    Science.gov (United States)

    Walker, A. P.; De Kauwe, M. G.; Medlyn, B. E.; Zaehle, S.; Luus, K. A.; Ryan, E.; Xia, J.; Norby, R. J.

    2015-12-01

    Plant photosynthetic rates increase and stomatal apertures decrease in response to elevated atmospheric CO[2] (eCO2), increasing both plant carbon (C) availability and water use efficiency. These physiological responses to eCO2 are well characterised and understood, however the ecological effects of these responses as they cascade through a suite of plant and ecosystem processes are complex and subject to multiple interactions and feedbacks. Therefore the response of the terrestrial carbon sink to increasing atmospheric CO[2] remains the largest uncertainty in global C cycle modelling to date, and is a huge contributor to uncertainty in climate change projections. Phase 2 of the FACE Model-Data Synthesis (FACE-MDS) project synthesises ecosystem observations from five long-term Free-Air CO[2] Enrichment (FACE) experiments and one open top chamber (OTC) experiment to evaluate the assumptions of a suite of terrestrial ecosystem models. The experiments are: The evergreen needleleaf Duke Forest FACE (NC), the deciduous broadleaf Oak Ridge FACE (TN), the prairie heating and FACE (WY), and the Nevada desert FACE, and the evergreen scrub oak OTC (FL). An assumption centered approach is being used to analyse: the interaction between eCO2 and water limitation on plant productivity; the interaction between eCO2 and temperature on plant productivity; whether increased rates of soil decomposition observed in many eCO2 experiments can account for model deficiencies in N uptake shown during Phase 1 of the FACE-MDS; and tracing carbon through the ecosystem to identify the exact cause of changes in ecosystem C storage.

  19. Cardiovascular and ventilatory responses to electrically induced cycling with complete epidural anaesthesia in humans

    DEFF Research Database (Denmark)

    Kjaer, M; Perko, G; Secher, N H

    1994-01-01

    Cardiovascular and ventilatory responses to electrically induced dynamic exercise were investigated in eight healthy young males with afferent neural influence from the legs blocked by epidural anaesthesia (25 ml 2% lidocaine) at L3-L4. This caused cutaneous sensory anaesthesia below T8-T9 and co...

  20. Ventilatory responses of children to changes in deadspace volume. Studies using the T-piece (Mapleson F) system.

    Science.gov (United States)

    Charlton, A J; Lindahl, S G; Hatch, D J

    1985-06-01

    Twelve patients (4.3-25.3 kg) undergoing minor surgical procedures were investigated during halothane anaesthesia with spontaneous breathing through a modified T-piece (Mapleson F) with an apparatus deadspace that could be changed from 2 ml (VDsmall) to 16 ml (VDlarge). Immediately following the switch from VDsmall to Vlarge ETCO2 (mean +/- 1 SD) increased from 6.89 +/- 1.09% to 7.61 +/- 1.14% (ns) then gradually decreased during a 10-min period. The initial plateau of FlCO2 (mean +/- 1 SD) with VDlarge was 0.74 +/- 0.34%, but gradually decreased to 0.63 +/- 0.25% after 10 min. This was achieved by an increase in VE (P less than 0.05 by 2 min). After 10 min VE had increased by more than 40% (P less than 0.01) as a result of an increase in VT (mean +/- 1 SD) of 14.6 +/- 6.5 ml. After 10 min of VDlarge ventilation, VA and VCO2 were maintained at VDsmall values. The adequate ventilatory response to the large deadspace was seen in all patients, but the ventilatory efficiency, as judged by VD/VT and VENCO2 ratios, was reduced significantly in the children weighing less than 10 kg.

  1. Diversity of CO2-concentrating mechanisms and responses to CO2 concentration in marine and freshwater diatoms.

    Science.gov (United States)

    Clement, Romain; Jensen, Erik; Prioretti, Laura; Maberly, Stephen C; Gontero, Brigitte

    2017-06-01

    The presence of CO2-concentrating mechanisms (CCMs) is believed to be one of the characteristics that allows diatoms to thrive in many environments and to be major contributors to global productivity. Here, the type of CCM and the responses to variable CO2 concentration were studied in marine and freshwater diatoms. At 400 ppm, there was a large diversity in physiological and biochemical mechanisms among the species. While Phaeodactylum tricornutum mainly used HCO3-, Thalassiosira pseudonana mainly used CO2. Carbonic anhydrase was an important component of the CCM in all species and C4 metabolism was absent, even with T. weissflogii. For all species, at 20 000 ppm, the affinity for dissolved inorganic carbon was lower than at 400 ppm CO2 and the reliance on CO2 was higher. Despite the difference in availability of inorganic carbon in marine and fresh waters, there were only small differences in CCMs between species from the two environments, and Navicula pelliculosa behaved similarly when grown in the two environments. The results suggest that species-specific differences are great, and more important than environmental differences in determining the nature and effectiveness of the CCM in diatoms. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  2. Changes in Ventilatory Response to Exercise in Trained Athletes: Respiratory Physiological Benefits Beyond Cardiovascular Performance.

    Science.gov (United States)

    di Paco, Adriano; Dubé, Bruno-Pierre; Laveneziana, Pierantonio

    2017-05-01

    The beneficial impact of an 8-month competitive season on the ventilatory profile response to exercise in soccer players has never been evaluated. Ventilatory profile (evaluated by determining individual tidal volume [VT] relative to minute ventilation [VE] inflection points during exercise) and metabolic responses to incremental exercise were evaluated in 2 professional soccer teams before and after an 8-month competitive season. No differences between teams in anthropometric characteristics or in resting cardiopulmonary variables, included oxygen uptake (VO2) and heart rate (HR), before and during the competitive season were found. At iso-speed, there were overall improvements in carbon dioxide output (VCO2), VE/VO2, VE/VCO2, VE and respiratory frequency (fR) during the season. The VT/VE inflection points 1 and 2 occurred with greater exercise time, HR, VO2, VCO2, VE and VT during the competitive season. Despite very high baseline performance and a negligible improvement in VO2, an 8-month competitive season improved ventilatory profile response to exercise in elite athletes. Copyright © 2016 SEPAR. Publicado por Elsevier España, S.L.U. All rights reserved.

  3. Simulated response of conterminous United States ecosystems to climate change at different levels of fire suppression, CO2 emission rate, and growth response to CO2

    Science.gov (United States)

    James M. Lenihan; Dominique Bachelet; Ronald P. Neilson; Raymond Drapek

    2008-01-01

    A modeling experiment was designed to investigate the impact of fire management, CO2 emission rate, and the growth response to CO2 on the response of ecosystems in the conterminous United States to climate scenarios produced by three different general circulation models (GCMs) as simulated by the MCl Dynamic General...

  4. Ventilatory Responsiveness of Goats with Ablated Carotid Bodies,

    Science.gov (United States)

    1982-06-03

    and CSF, and on responses to respiratory stimuli (hypercapnia, hypoxia, injection of cyanide). Hyperventilation in response to acute hypoxia was...Environmental Medicine, Natick 01760; and Departments of Anesthesia and Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston...techniques of Pappenheimer et al (22). 2 The carotid bodies were excised under general anesthesia . From a ventral midline incision in the neck, the

  5. Whole-body CO2 production as an index of the metabolic response to sepsis

    Science.gov (United States)

    Whole-body carbon dioxide (CO2) production (RaCO2) is an index of substrate oxidation and energy expenditure; therefore, it may provide information about the metabolic response to sepsis. Using stable isotope techniques, we determined RaCO2 and its relationship to protein and glucose metabolism in m...

  6. Soil carbon dioxide (CO 2 ) efflux of two shrubs in response to plant ...

    African Journals Online (AJOL)

    Although plant density should affect soil carbon dioxide (CO2) efflux and carbon cycling in semi-arid regions, the effects of plant density on soil CO2 efflux are not well known. This study was performed to investigate the responses of soil CO2 efflux of two dominant shrubs (Caragana korshinkii and Salix psammophila) to ...

  7. The response of photosynthesis and stomatal conductance to rising [CO2]: mechanisms and environmental interactions.

    Science.gov (United States)

    Ainsworth, Elizabeth A; Rogers, Alistair

    2007-03-01

    This review summarizes current understanding of the mechanisms that underlie the response of photosynthesis and stomatal conductance to elevated carbon dioxide concentration ([CO2]), and examines how downstream processes and environmental constraints modulate these two fundamental responses. The results from free-air CO2 enrichment (FACE) experiments were summarized via meta-analysis to quantify the mean responses of stomatal and photosynthetic parameters to elevated [CO2]. Elevation of [CO2] in FACE experiments reduced stomatal conductance by 22%, yet, this reduction was not associated with a similar change in stomatal density. Elevated [CO2] stimulated light-saturated photosynthesis (Asat) in C3 plants grown in FACE by an average of 31%. However, the magnitude of the increase in Asat varied with functional group and environment. Functional groups with ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco)-limited photosynthesis at elevated [CO2] had greater potential for increases in Asat than those where photosynthesis became ribulose-1,5-bisphosphate (RubP)-limited at elevated [CO2]. Both nitrogen supply and sink capacity modulated the response of photosynthesis to elevated [CO2] through their impact on the acclimation of carboxylation capacity. Increased understanding of the molecular and biochemical mechanisms by which plants respond to elevated [CO2], and the feedback of environmental factors upon them, will improve our ability to predict ecosystem responses to rising [CO2] and increase our potential to adapt crops and managed ecosystems to future atmospheric [CO2].

  8. Altered breathing mechanics and ventilatory response during exercise in children born extremely preterm.

    Science.gov (United States)

    MacLean, J E; DeHaan, K; Fuhr, D; Hariharan, S; Kamstra, B; Hendson, L; Adatia, I; Majaesic, C; Lovering, A T; Thompson, R B; Nicholas, D; Thebaud, B; Stickland, M K

    2016-11-01

    Extreme preterm birth confers risk of long-term impairments in lung function and exercise capacity. There are limited data on the factors contributing to exercise limitation following extreme preterm birth. This study examined respiratory mechanics and ventilatory response during exercise in a large cohort of children born extremely preterm (EP). This cohort study included children 8-12 years of age who were born EP (≤28 weeks gestation) between 1997 and 2004 and treated in a large regionalised neonatal intensive care unit in western Canada. EP children were divided into no/mild bronchopulmonary dysplasia (BPD) (ie, supplementary oxygen or ventilation ceased before 36 weeks gestational age; n=53) and moderate/severe BPD (ie, continued supplementary oxygen or ventilation at 36 weeks gestational age; n=50). Age-matched control children (n=65) were born at full term. All children attempted lung function and cardiopulmonary exercise testing measurements. Compared with control children, EP children had lower airway flows and diffusion capacity but preserved total lung capacity. Children with moderate/severe BPD had evidence of gas trapping relative to other groups. The mean difference in exercise capacity (as measured by oxygen uptake (VO2)% predicted) in children with moderate/severe BPD was -18±5% and -14±5.0% below children with no/mild BPD and control children, respectively. Children with moderate/severe BPD demonstrated a potentiated ventilatory response and greater prevalence of expiratory flow limitation during exercise compared with other groups. Resting lung function did not correlate with exercise capacity. Expiratory flow limitation and an exaggerated ventilatory response contribute to respiratory limitation to exercise in children born EP with moderate/severe BPD. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  9. Ventilatory responses to muscle metaboreflex activation in chronic obstructive pulmonary disease.

    Science.gov (United States)

    Bruce, Richard M; Turner, Alice; White, Michael J

    2016-10-15

    Recent evidence indicates a role for group III/IV muscle afferents in reflex control of the human ventilatory response to exercise. Dyspnoea in chronic obstructive pulmonary disease (COPD) may be linked to this reflex response. This study shows that activation of the muscle metaboreflex causes a ventilatory response in COPD patients but not in healthy controls. This indicates abnormal involvement of muscle afferents in the control of ventilation in COPD which may be a contributing factor to exercise dyspnoea. Blockade of thin fibre muscle afferent feedback during dynamic exercise reduces exercise hyperpnoea in health and chronic obstructive pulmonary disease (COPD). Therefore, we hypothesised that activation of the muscle metaboreflex at rest would cause hyperpnoea. We evaluated the effect of muscle metaboreflex activation on ventilation, in resting COPD patients and healthy participants. Following a bout of rhythmic hand grip exercise, post exercise circulatory occlusion (PECO) was applied to the resting forearm to sustain activation of the muscle metaboreflex, in 18 COPD patients (FEV 1 /FVC ratio abnormally involved in the control of ventilation in COPD and may be a contributing factor to exercise dyspnoea. © 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.

  10. Developmental stage specificity of transcriptional, biochemical and CO2 efflux responses of leaf dark respiration to growth of Arabidopsis thaliana at elevated [CO2].

    Science.gov (United States)

    Markelz, R J Cody; Vosseller, Lauren N; Leakey, Andrew D B

    2014-11-01

    Plant respiration responses to elevated growth [CO(2)] are key uncertainties in predicting future crop and ecosystem function. In particular, the effects of elevated growth [CO(2)] on respiration over leaf development are poorly understood. This study tested the prediction that, due to greater whole plant photoassimilate availability and growth, elevated [CO(2)] induces transcriptional reprogramming and a stimulation of nighttime respiration in leaf primordia, expanding leaves and mature leaves of Arabidopsis thaliana. In primordia, elevated [CO(2)] altered transcript abundance, but not for genes encoding respiratory proteins. In expanding leaves, elevated [CO(2)] induced greater glucose content and transcript abundance for some respiratory genes, but did not alter respiratory CO(2) efflux. In mature leaves, elevated [CO(2)] led to greater glucose, sucrose and starch content, plus greater transcript abundance for many components of the respiratory pathway, and greater respiratory CO(2) efflux. Therefore, growth at elevated [CO(2)] stimulated dark respiration only after leaves transitioned from carbon sinks into carbon sources. This coincided with greater photoassimilate production by mature leaves under elevated [CO(2)] and peak respiratory transcriptional responses. It remains to be determined if biochemical and transcriptional responses to elevated [CO(2)] in primordial and expanding leaves are essential prerequisites for subsequent alterations of respiratory metabolism in mature leaves. © 2014 John Wiley & Sons Ltd.

  11. Seaweed community response to a massive CO2 input

    Science.gov (United States)

    Sangil, Carlos; Clemente, Sabrina; Brito, Alberto; Rodríguez, Adriana; Balsalobre, Marc; Mendoza, José Carlos; Martínez, David; Hernández, José Carlos

    2016-09-01

    Changes in the structure of seaweed communities were examined following a massive CO2 input caused by a submarine eruption near the coast of El Hierro island (Canary Islands, Spain). The event lasted almost five months (October 2011-March 2012) and created a significant pH gradient. Specifically, we compared three different zones: highly affected with extreme low pH (6.7-7.3), affected with low pH (7.6-7.8), and unaffected ambient pH zone (∼8.1) according to the pH gradient generated by the predominate currents and waves in the south of the island. Studies were carried out before, during and after the CO2 input event in each zone. We found community-wide effects on seaweed communities during the eruption; these included changes in species abundance and changes in the diversity. However, changes in all these community traits were only evident in the highly affected zone, where there were major shifts in the seaweed community, with a replacement of Lobophora variegata by ephemeral seaweeds. Lobophora variegata dropped in cover from 87-94 to 27% while ephemeral seaweeds increased 6-10 to 29%. When the impact ended Lobophora variegata began to recover reaching a cover higher than 60%. In the moderate affected area the Lobophora variegata canopies maintained their integrity avoiding phase shifts to turfs. Here the only significant changes were the reduction of the cover of the crustose and geniculate coralline algae.

  12. Ventilatory and metabolic responses of burrowing owls, Athene cunicularia, to moderate and extreme hypoxia: analysis of the hypoxic ventilatory threshold vs. hemoglobin oxygen affinity relationship in birds.

    Science.gov (United States)

    Kilgore, Delbert L; Boggs, Dona F; Kilgore, Trevor J; Colby, Conrad; Williams, Burl R; Bavis, Ryan W

    2008-06-01

    We measured ventilation, oxygen consumption and blood gases in burrowing owls (Athene cunicularia) breathing moderate and extreme hypoxic gas mixtures to determine their hypoxic ventilatory threshold (HVT) and to assess if they, like other birds and mammals, exhibit a relationship between HVT and hemoglobin O2 affinity (P(50)) of their blood. An earlier report of an attenuated ventilatory responsiveness of this species to hypoxia was enigmatic given the low O2 affinity (high P(50)) of burrowing owl hemoglobin. In the current study, burrowing owls breathing 11% and 9% O2 showed a significantly elevated total ventilation. The arterial partial pressure of oxygen (PaO2) at which ventilation is elevated above normoxic values in burrowing owls was 58 mm Hg. This threshold value conforms well to expectations based on the high P(50) of their hemoglobin and the HVT vs. P(50) relationship for birds developed in this study. Correcting for phylogenetic relatedness in the multi-species analysis had no effect on the HVT vs. P(50) relationship. Also, because burrowing owls in this study did not show a hypometabolic response at any level of hypoxia (even at 9% O2); HVT described in terms of percent change in oxygen convection requirement is identical to that based on ventilation alone.

  13. Evolutionary context for understanding and manipulating plant responses to past, present and future atmospheric [CO2

    Science.gov (United States)

    Leakey, Andrew D. B.; Lau, Jennifer A.

    2012-01-01

    Variation in atmospheric [CO2] is a prominent feature of the environmental history over which vascular plants have evolved. Periods of falling and low [CO2] in the palaeo-record appear to have created selective pressure for important adaptations in modern plants. Today, rising [CO2] is a key component of anthropogenic global environmental change that will impact plants and the ecosystem goods and services they deliver. Currently, there is limited evidence that natural plant populations have evolved in response to contemporary increases in [CO2] in ways that increase plant productivity or fitness, and no evidence for incidental breeding of crop varieties to achieve greater yield enhancement from rising [CO2]. Evolutionary responses to elevated [CO2] have been studied by applying selection in controlled environments, quantitative genetics and trait-based approaches. Findings to date suggest that adaptive changes in plant traits in response to future [CO2] will not be consistently observed across species or environments and will not be large in magnitude compared with physiological and ecological responses to future [CO2]. This lack of evidence for strong evolutionary effects of elevated [CO2] is surprising, given the large effects of elevated [CO2] on plant phenotypes. New studies under more stressful, complex environmental conditions associated with climate change may revise this view. Efforts are underway to engineer plants to: (i) overcome the limitations to photosynthesis from today's [CO2] and (ii) benefit maximally from future, greater [CO2]. Targets range in scale from manipulating the function of a single enzyme (e.g. Rubisco) to adding metabolic pathways from bacteria as well as engineering the structural and functional components necessary for C4 photosynthesis into C3 leaves. Successfully improving plant performance will depend on combining the knowledge of the evolutionary context, cellular basis and physiological integration of plant responses to varying

  14. Elevated-CO2 Response of Stomata and Its Dependence on Environmental Factors

    Science.gov (United States)

    Xu, Zhenzhu; Jiang, Yanling; Jia, Bingrui; Zhou, Guangsheng

    2016-01-01

    Stomata control the flow of gases between plants and the atmosphere. This review is centered on stomatal responses to elevated CO2 concentration and considers other key environmental factors and underlying mechanisms at multiple levels. First, an outline of general responses in stomatal conductance under elevated CO2 is presented. Second, stomatal density response, its development, and the trade-off with leaf growth under elevated CO2 conditions are depicted. Third, the molecular mechanism regulating guard cell movement at elevated CO2 is suggested. Finally, the interactive effects of elevated CO2 with other factors critical to stomatal behavior are reviewed. It may be useful to better understand how stomata respond to elevated CO2 levels while considering other key environmental factors and mechanisms, including molecular mechanism, biochemical processes, and ecophysiological regulation. This understanding may provide profound new insights into how plants cope with climate change. PMID:27242858

  15. Phenotypic Plasticity Conditions the Response of Soybean Seed Yield to Elevated Atmospheric CO2 Concentration.

    Science.gov (United States)

    Kumagai, Etsushi; Aoki, Naohiro; Masuya, Yusuke; Shimono, Hiroyuki

    2015-11-01

    Selection for cultivars with superior responsiveness to elevated atmospheric CO2 concentrations (eCO2) is a powerful option for boosting crop productivity under future eCO2. However, neither criteria for eCO2 responsiveness nor prescreening methods have been established. The purpose of this study was to identify traits responsible for eCO2 responsiveness of soybean (Glycine max). We grew 12 Japanese and U.S. soybean cultivars that differed in their maturity group and determinacy under ambient CO2 and eCO2 for 2 years in temperature gradient chambers. CO2 elevation significantly increased seed yield per plant, and the magnitude varied widely among the cultivars (from 0% to 62%). The yield increase was best explained by increased aboveground biomass and pod number per plant. These results suggest that the plasticity of pod production under eCO2 results from biomass enhancement, and would therefore be a key factor in the yield response to eCO2, a resource-rich environment. To test this hypothesis, we grew the same cultivars at low planting density, a resource-rich environment that improved the light and nutrient supplies by minimizing competition. Low planting density significantly increased seed yield per plant, and the magnitude ranged from 5% to 105% among the cultivars owing to increased biomass and pod number per plant. The yield increase due to low-density planting was significantly positively correlated with the eCO2 response in both years. These results confirm our hypothesis and suggest that high plasticity of biomass and pod production at a low planting density reveals suitable parameters for breeding to maximize soybean yield under eCO2. © 2015 American Society of Plant Biologists. All Rights Reserved.

  16. Metabolomics and Proteomics of Brassica napus Guard Cells in Response to Low CO2.

    Science.gov (United States)

    Geng, Sisi; Yu, Bing; Zhu, Ning; Dufresne, Craig; Chen, Sixue

    2017-01-01

    Stomatal guard cell response to various stimuli is an important process that balances plant carbon dioxide (CO2) uptake and water transpiration. Elevated CO2 induces stomatal closure, while low CO2 promotes stomatal opening. The signaling process of elevated CO2 induced stomatal closure has been extensively studied in recent years. However, the mechanism of low CO2 induced stomatal opening is not fully understood. Here we report metabolomic and proteomic responses of Brassica napus guard cells to low CO2 using hyphenated mass spectrometry technologies. A total of 411 metabolites and 1397 proteins were quantified in a time-course study of low CO2 effects. Metabolites and proteins that exhibited significant changes are overrepresented in fatty acid metabolism, starch and sucrose metabolism, glycolysis and redox regulation. Concomitantly, multiple hormones that promote stomatal opening increased in response to low CO2. Interestingly, jasmonic acid precursors were diverted to a branch pathway of traumatic acid biosynthesis. These results indicate that the low CO2 response is mediated by a complex crosstalk between different phytohormones.

  17. Elevated CO2-Induced Responses in Stomata Require ABA and ABA Signaling.

    Science.gov (United States)

    Chater, Caspar; Peng, Kai; Movahedi, Mahsa; Dunn, Jessica A; Walker, Heather J; Liang, Yun-Kuan; McLachlan, Deirdre H; Casson, Stuart; Isner, Jean Charles; Wilson, Ian; Neill, Steven J; Hedrich, Rainer; Gray, Julie E; Hetherington, Alistair M

    2015-10-19

    An integral part of global environment change is an increase in the atmospheric concentration of CO2 ([CO2]) [1]. Increased [CO2] reduces leaf stomatal apertures and density of stomata that plays out as reductions in evapotranspiration [2-4]. Surprisingly, given the importance of transpiration to the control of terrestrial water fluxes [5] and plant nutrient acquisition [6], we know comparatively little about the molecular components involved in the intracellular signaling pathways by which [CO2] controls stomatal development and function [7]. Here, we report that elevated [CO2]-induced closure and reductions in stomatal density require the generation of reactive oxygen species (ROS), thereby adding a new common element to these signaling pathways. We also show that the PYR/RCAR family of ABA receptors [8, 9] and ABA itself are required in both responses. Using genetic approaches, we show that ABA in guard cells or their precursors is sufficient to mediate the [CO2]-induced stomatal density response. Taken together, our results suggest that stomatal responses to increased [CO2] operate through the intermediacy of ABA. In the case of [CO2]-induced reductions in stomatal aperture, this occurs by accessing the guard cell ABA signaling pathway. In both [CO2]-mediated responses, our data are consistent with a mechanism in which ABA increases the sensitivity of the system to [CO2] but could also be explained by requirement for a CO2-induced increase in ABA biosynthesis specifically in the guard cell lineage. Furthermore, the dependency of stomatal [CO2] signaling on ABA suggests that the ABA pathway is, in evolutionary terms, likely to be ancestral. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  18. Hemiparasite abundance in an alpine treeline ecotone increases in response to atmospheric CO(2) enrichment.

    Science.gov (United States)

    Hättenschwiler, Stephan; Zumbrunn, Thomas

    2006-02-01

    Populations of the annual hemiparasites Melampyrum pratense L. and Melampyrum sylvaticum L. were studied at the treeline in the Swiss Alps after 3 years of in situ CO(2) enrichment. The total density of Melampyrum doubled to an average of 44 individuals per square meter at elevated CO(2) compared to ambient CO(2). In response to elevated CO(2), the height of the more abundant and more evenly distributed M. pratense increased by 20%, the number of seeds per fruit by 21%, and the total seed dry mass per fruit by 27%, but the individual seed size did not change. These results suggest that rising atmospheric CO(2) may stimulate the reproductive output and increase the abundance of Melampyrum in the alpine treeline ecotone. Because hemiparasites can have important effects on community dynamics and ecosystem processes, notably the N cycle, changing Melampyrum abundance may potentially influence the functioning of alpine ecosystems in a future CO(2)-rich atmosphere.

  19. Effects of elevated CO2 on litter chemistry and subsequent invertebrate detritivore feeding responses.

    Directory of Open Access Journals (Sweden)

    Matthew W Dray

    Full Text Available Elevated atmospheric CO2 can change foliar tissue chemistry. This alters leaf litter palatability to macroinvertebrate detritivores with consequences for decomposition, nutrient turnover, and food-web structure. Currently there is no consensus on the link between CO2 enrichment, litter chemistry, and macroinvertebrate-mediated leaf decomposition. To identify any unifying mechanisms, we presented eight invertebrate species from aquatic and terrestrial ecosystems with litter from Alnus glutinosa (common alder or Betula pendula (silver birch trees propagated under ambient (380 ppm or elevated (ambient +200 ppm CO2 concentrations. Alder litter was largely unaffected by CO2 enrichment, but birch litter from leaves grown under elevated CO2 had reduced nitrogen concentrations and greater C/N ratios. Invertebrates were provided individually with either (i two litter discs, one of each CO2 treatment ('choice', or (ii one litter disc of each CO2 treatment alone ('no-choice'. Consumption was recorded. Only Odontocerum albicorne showed a feeding preference in the choice test, consuming more ambient- than elevated-CO2 birch litter. Species' responses to alder were highly idiosyncratic in the no-choice test: Gammarus pulex and O. albicorne consumed more elevated-CO2 than ambient-CO2 litter, indicating compensatory feeding, while Oniscus asellus consumed more of the ambient-CO2 litter. No species responded to CO2 treatment when fed birch litter. Overall, these results show how elevated atmospheric CO2 can alter litter chemistry, affecting invertebrate feeding behaviour in species-specific ways. The data highlight the need for greater species-level information when predicting changes to detrital processing-a key ecosystem function-under atmospheric change.

  20. Importance of vegetation processes for model spread in the fast precipitation response to CO2 forcing

    Science.gov (United States)

    DeAngelis, Anthony M.; Qu, Xin; Hall, Alex

    2016-12-01

    In the current generation of climate models, the projected increase in global precipitation over the 21st century ranges from 2% to 10% under a high-emission scenario. Some of this uncertainty can be traced to the rapid response to carbon dioxide (CO2) forcing. We analyze an ensemble of simulations to better understand model spread in this rapid response. A substantial amount is linked to how the land surface partitions a change in latent versus sensible heat flux in response to the CO2-induced radiative perturbation; a larger increase in sensible heat results in a larger decrease in global precipitation. Model differences in the land surface response appear to be strongly related to the vegetation response to increased CO2, specifically, the closure of leaf stomata. Future research should thus focus on evaluation of the vegetation physiological response, including stomatal conductance parameterizations, for the purpose of constraining the fast response of Earth's hydrologic cycle to CO2 forcing.

  1. Inorganic nitrogen form: a major player in wheat and Arabidopsis responses to elevated CO2.

    Science.gov (United States)

    Rubio-Asensio, José S; Bloom, Arnold J

    2017-05-01

    Critical for predicting the future of primary productivity is a better understanding of plant responses to rising atmospheric carbon dioxide (CO2) concentration. This review considers recent results on the role of the inorganic nitrogen (N) forms nitrate (NO3-) and ammonium (NH4+) in determining the responses of wheat and Arabidopsis to elevated atmospheric CO2 concentration. Here, we identify four key issues: (i) the possibility that different plant species respond similarly to elevated CO2 if one accounts for the N form that they are using; (ii) the major influence that plant-soil N interactions have on plant responses to elevated CO2; (iii) the observation that elevated CO2 may favor the uptake of one N form over others; and (iv) the finding that plants receiving NH4+ nutrition respond more positively to elevated CO2 than those receiving NO3- nutrition because elevated CO2 inhibits the assimilation of NO3- in shoots of C3 plants. We conclude that the form and amount of N available to plants from the rhizosphere and plant preferences for the different N forms are essential for predicting plant responses to elevated CO2. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  2. Elevated CO2 affects plant responses to variation in boron availability

    Science.gov (United States)

    Effects of elevated CO2 on N relations are well studied, but effects on other nutrients, especially micronutrients, are not. We investigated effects of elevated CO2 on response to variation in boron (B) availability in three unrelated species: geranium (Pelargonium x hortorum), barley (Hordeum vulga...

  3. Response of a Sphagnum bog plant community to elevated CO2 and N supply

    NARCIS (Netherlands)

    Heijmans, M.M.P.D.; Klees, H.; Visser, de W.; Berendse, F.

    2002-01-01

    The response of plant growth to rising CO2 levels appears to depend on nutrient availability, but it is not known whether the growth of bog plants reacts similarly. We therefore studied the effects of elevated CO2 in combination with N supply on the growth of Sphagnum mosses and vascular plants in

  4. Absence of OsβCA1 causes a CO2 deficit and affects leaf photosynthesis and the stomatal response to CO2 in rice.

    Science.gov (United States)

    Chen, Taiyu; Wu, Huan; Wu, Jiemin; Fan, Xiaolei; Li, Xianghua; Lin, Yongjun

    2017-04-01

    Plants always adjust the opening of stomatal pores to adapt to the environment, for example CO2 concentration ([CO2 ]), humidity and temperature. Low [CO2 ] will trigger the opening of stomatal pores to absorb extra CO2 . However, little is known about how CO2 supply affects the carbon fixation and opening of stomatal pores in rice. Here, a chloroplast-located gene coding for β-carbonic anhydrase (βCA) was found to be involved in carbon assimilation and the CO2 -mediated stomatal pore response in rice. OsβCA1 was constitutively expressed in all tissues and its transcripts were induced by high [CO2 ] in leaves. Both T-DNA mutant and RNA interference lines showed phenotypes of lower biomass and CA activities. Knockout of OsβCA1 obviously decreased photosynthetic capacity, as demonstrated by the increased CO2 compensation point and decreased light saturation point in the mutant, while knockout increased the opening ratio of stomatal pores and the rate of water loss. Moreover, the mutant showed a delayed response to low [CO2 ], and stomatal pores could not be closed to the same degree as those of wild type even though the stomatal pores could rapidly respond to high [CO2 ]. Genome-wide gene expression analysis via RNA sequencing demonstrated that the transcript abundance of genes related to Rubisco, photosystem compounds and the opening of stomatal pores was globally upregulated in the mutant. Taken together, the inadequate CO2 supply caused by the absence of OsβCA1 reduces photosynthetic efficiency, triggers the opening of stomatal pores and finally decreases their sensitivity to CO2 fluctuation. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

  5. Do gender differences exist in the ventilatory response to progressive exercise in males and females of average fitness?

    Science.gov (United States)

    Kilbride, Emma; McLoughlin, Paul; Gallagher, Charles G; Harty, Helen R

    2003-08-01

    Gender differences in lung volumes and flow rates, and in respiratory control have been documented previously. How these gender differences affect exercise responses in normal subjects is less clear, particularly as many studies involved highly fit subjects. This study aimed to investigate potential gender differences occurring during progressive exercise in healthy males and females of average fitness. Fourteen males and ten females of mean (SD) age 23 (0.35) years completed a progressive exercise test to exhaustion on a cycle ergometer, with a ramp increase of 15 W min(-1) (female) or 20 W min(-1) (male). All females were studied during the follicular phase of their menstrual cycle. Cardiorespiratory variables were measured, breath by breath, and values were compared at rest, at 40 W, at physiologically equivalent workloads below, at and above the gas exchange threshold and at peak oxygen uptake (VO(2peak)). Mean VO(2peak) (SEM) was 32.4 (2.01) ml kg(-1) min(-1) for the females and 41.9 (1.80) ml kg(-1) min(-1) for the males. Females had a significantly lower end-tidal partial CO(2) pressure at rest and throughout exercise. Increases in exercise minute ventilation were achieved by a significantly greater tidal volume in males, whereas females adopted a significantly greater breathing frequency. Ratings of respiratory discomfort were significantly greater in the male group at physiologically equivalent workloads compared to the female group. This study shows gender differences exist in the ventilatory and sensory response to progressive exercise in untrained subjects. Further work is required to ascertain if these effects are altered during the luteal phase of the menstrual cycle.

  6. CO2-Induced Changes in Wheat Grain Composition: Meta-Analysis and Response Functions

    Directory of Open Access Journals (Sweden)

    Malin C. Broberg

    2017-04-01

    Full Text Available Elevated carbon dioxide (eCO2 stimulates wheat grain yield, but simultaneously reduces protein/nitrogen (N concentration. Also, other essential nutrients are subject to change. This study is a synthesis of wheat experiments with eCO2, estimating the effects on N, minerals (B, Ca, Cd, Fe, K, Mg, Mn, Na, P, S, Zn, and starch. The analysis was performed by (i deriving response functions to assess the gradual change in element concentration with increasing CO2 concentration, (ii meta-analysis to test the average magnitude and significance of observed effects, and (iii relating CO2 effects on minerals to effects on N and grain yield. Responses ranged from zero to strong negative effects of eCO2 on mineral concentration, with the largest reductions for the nutritionally important elements of N, Fe, S, Zn, and Mg. Together with the positive but small and non-significant effect on starch concentration, the large variation in effects suggests that CO2-induced responses cannot be explained only by a simple dilution model. To explain the observed pattern, uptake and transport mechanisms may have to be considered, along with the link of different elements to N uptake. Our study shows that eCO2 has a significant effect on wheat grain stoichiometry, with implications for human nutrition in a world of rising CO2.

  7. CO2-response function of radiation use efficiency in rice for climate change scenarios

    Directory of Open Access Journals (Sweden)

    Nereu Augusto Streck

    2012-07-01

    Full Text Available The objective of this work was to evaluate a generalized response function to the atmospheric CO2 concentration [f(CO2] by the radiation use efficiency (RUE in rice. Experimental data on RUE at different CO2 concentrations were collected from rice trials performed in several locations around the world. RUE data were then normalized, so that all RUE at current CO2 concentration were equal to 1. The response function was obtained by fitting normalized RUE versus CO2 concentration to a Morgan-Mercer-Flodin (MMF function, and by using Marquardt's method to estimate the model coefficients. Goodness of fit was measured by the standard deviation of the estimated coefficients, the coefficient of determination (R², and the root mean square error (RMSE. The f(CO2 describes a nonlinear sigmoidal response of RUE in rice, in function of the atmospheric CO2 concentration, which has an ecophysiological background, and, therefore, renders a robust function that can be easily coupled to rice simulation models, besides covering the range of CO2 emissions for the next generation of climate scenarios for the 21st century.

  8. Photosynthesis and metabolite responses of Isatis indigotica Fortune to elevated [CO2

    Directory of Open Access Journals (Sweden)

    Ping Li

    2017-08-01

    Full Text Available Climate change is affecting global crop productivity, food quality, and security. However, few studies have addressed the mechanism by which elevated CO2 may affect the growth of medicinal plants. Isatis indigotica Fortune is a widely used Chinese medicinal herb with multiple pharmacological properties. To investigate the physiological mechanism of I. indigotica response to elevated [CO2], plants were grown at either ambient [CO2] (385 μmol mol−1 or elevated [CO2] (590 μmol mol−1 in an open-top chamber (OTC experimental facility in North China. A significant reduction in transpiration rate (Tr and stomatal conductance (gs and a large increase in water-use efficiency contributed to an increase in net photosynthetic rate (Pn under elevated [CO2] 76 days after sowing. Leaf non-photochemical quenching (NPQ was decreased, so that more energy was used in effective quantum yield of PSII photochemistry (ΦPSII under elevated [CO2]. High ΦPSII, meaning high electron transfer efficiency, also increased Pn. The [CO2]-induced increase in photosynthesis significantly increased biomass by 36.8%. Amounts of metabolic compounds involved in sucrose metabolism, pyrimidine metabolism, flavonoid biosynthesis, and other processes in leaves were reduced under elevated [CO2]. These results showed that the fertilization effect of elevated [CO2] is conducive to increasing dry weight but not secondary metabolism in I. indigotica.

  9. Unique responsiveness of angiosperm stomata to elevated CO2 explained by calcium signalling.

    Science.gov (United States)

    Brodribb, Timothy J; McAdam, Scott A M

    2013-01-01

    Angiosperm and conifer tree species respond differently when exposed to elevated CO2, with angiosperms found to dynamically reduce water loss while conifers appear insensitive. Such distinct responses are likely to affect competition between these tree groups as atmospheric CO2 concentration rises. Seeking the mechanism behind this globally important phenomenon we targeted the Ca(2+)-dependent signalling pathway, a mediator of stomatal closure in response to elevated CO2, as a possible explanation for the differentiation of stomatal behaviours. Sampling across the diversity of vascular plants including lycophytes, ferns, gymnosperms and angiosperms we show that only angiosperms possess the stomatal behaviour and prerequisite genetic coding, linked to Ca(2+)-dependent stomatal signalling. We conclude that the evolution of Ca(2+)-dependent stomatal signalling gives angiosperms adaptive benefits in terms of highly efficient water use, but that stomatal sensitivity to high CO2 may penalise angiosperm productivity relative to other plant groups in the current era of soaring atmospheric CO2.

  10. Forest response to elevated CO2 is conserved across a broad range of productivity

    Science.gov (United States)

    Norby, Richard J.; DeLucia, Evan H.; Gielen, Birgit; Calfapietra, Carlo; Giardina, Christian P.; King, John S.; Ledford, Joanne; McCarthy, Heather R.; Moore, David J. P.; Ceulemans, Reinhart; De Angelis, Paolo; Finzi, Adrien C.; Karnosky, David F.; Kubiske, Mark E.; Lukac, Martin; Pregitzer, Kurt S.; Scarascia-Mugnozza, Giuseppe E.; Schlesinger, William H.; Oren, Ram

    2005-01-01

    Climate change predictions derived from coupled carbon-climate models are highly dependent on assumptions about feedbacks between the biosphere and atmosphere. One critical feedback occurs if C uptake by the biosphere increases in response to the fossil-fuel driven increase in atmospheric [CO2] (“CO2 fertilization”), thereby slowing the rate of increase in atmospheric [CO2]. Carbon exchanges between the terrestrial biosphere and atmosphere are often first represented in models as net primary productivity (NPP). However, the contribution of CO2 fertilization to the future global C cycle has been uncertain, especially in forest ecosystems that dominate global NPP, and models that include a feedback between terrestrial biosphere metabolism and atmospheric [CO2] are poorly constrained by experimental evidence. We analyzed the response of NPP to elevated CO2 (≈550 ppm) in four free-air CO2 enrichment experiments in forest stands. We show that the response of forest NPP to elevated [CO2] is highly conserved across a broad range of productivity, with a stimulation at the median of 23 ± 2%. At low leaf area indices, a large portion of the response was attributable to increased light absorption, but as leaf area indices increased, the response to elevated [CO2] was wholly caused by increased light-use efficiency. The surprising consistency of response across diverse sites provides a benchmark to evaluate predictions of ecosystem and global models and allows us now to focus on unresolved questions about carbon partitioning and retention, and spatial variation in NPP response caused by availability of other growth limiting resources. PMID:16330779

  11. Coupling of EIT with computational lung modeling for predicting patient-specific ventilatory responses.

    Science.gov (United States)

    Roth, Christian J; Becher, Tobias; Frerichs, Inéz; Weiler, Norbert; Wall, Wolfgang A

    2017-04-01

    Providing optimal personalized mechanical ventilation for patients with acute or chronic respiratory failure is still a challenge within a clinical setting for each case anew. In this article, we integrate electrical impedance tomography (EIT) monitoring into a powerful patient-specific computational lung model to create an approach for personalizing protective ventilatory treatment. The underlying computational lung model is based on a single computed tomography scan and able to predict global airflow quantities, as well as local tissue aeration and strains for any ventilation maneuver. For validation, a novel "virtual EIT" module is added to our computational lung model, allowing to simulate EIT images based on the patient's thorax geometry and the results of our numerically predicted tissue aeration. Clinically measured EIT images are not used to calibrate the computational model. Thus they provide an independent method to validate the computational predictions at high temporal resolution. The performance of this coupling approach has been tested in an example patient with acute respiratory distress syndrome. The method shows good agreement between computationally predicted and clinically measured airflow data and EIT images. These results imply that the proposed framework can be used for numerical prediction of patient-specific responses to certain therapeutic measures before applying them to an actual patient. In the long run, definition of patient-specific optimal ventilation protocols might be assisted by computational modeling.NEW & NOTEWORTHY In this work, we present a patient-specific computational lung model that is able to predict global and local ventilatory quantities for a given patient and any selected ventilation protocol. For the first time, such a predictive lung model is equipped with a virtual electrical impedance tomography module allowing real-time validation of the computed results with the patient measurements. First promising results

  12. Biochar addition induced the same plant responses as elevated CO2 in mine spoil.

    Science.gov (United States)

    Zhang, Yaling; Drigo, Barbara; Bai, Shahla Hosseini; Menke, Carl; Zhang, Manyun; Xu, Zhihong

    2017-10-31

    Nitrogen (N) limitation is one of the major constrain factors for biochar in improving plant growth, the same for elevated atmospheric carbon dioxide (CO2). Hence, we hypothesized that (1) biochar would induce the same plant responses as elevated CO2 under N-poor conditions; (2) elevated CO2 would decrease the potential of biochar application in improving plant growth. To test these hypotheses, we assessed the effects of pinewood biochar, produced at three pyrolytic temperatures (650, 750 and 850 °C), on C and N allocation at the whole-plant level of three plant species (Austrostipa ramossissima, Dichelachne micrantha and Isolepis nodosa) grown in the N poor mine spoil under both ambient (400 μL L(-1)) and elevated (700 μL L(-1)) CO2 concentrations. Our data showed that biochar addition (1) significantly decreased leaf total N and δ(15)N (P CO2 than under elevated CO2 concentration. Hence, it remained a strong possibility that biochar addition induced the same plant physiological responses as elevated CO2 in the N-deficient mine spoil. As expected, elevated CO2 decreased the ability of biochar addition in improving plant growth.

  13. Thermodynamic and kinetic response of microbial reactions to high CO2

    Directory of Open Access Journals (Sweden)

    Qusheng Jin

    2016-11-01

    Full Text Available Geological carbon sequestration captures CO2 from industrial sources and stores the CO2 in subsurface reservoirs, a viable strategy for mitigating global climate change. In assessing the environmental impact of the strategy, a key question is how microbial reactions respond to the elevated CO2 concentration. This study uses biogeochemical modeling to explore the influence of CO2 on the thermodynamics and kinetics of common microbial reactions in subsurface environments, including syntrophic oxidation, iron reduction, sulfate reduction, and methanogenesis. The results show that increasing CO2 levels decreases groundwater pH and modulates chemical speciation of weak acids in groundwater, which in turn affect microbial reactions in different ways and to different extents. Specifically, a thermodynamic analysis shows that increasing CO2 partial pressure lowers the energy available from syntrophic oxidation and acetoclastic methanogenesis, but raises the available energy of microbial iron reduction, hydrogenotrophic sulfate reduction and methanogenesis. Kinetic modeling suggests that high CO2 has the potential of inhibiting microbial sulfate reduction while promoting iron reduction. These results are consistent with the observations of previous laboratory and field studies, and highlight the complexity in microbiological responses to elevated CO2 abundance, and the potential power of biogeochemical modeling in evaluating and quantifying these responses.

  14. Effects of hydralazine on mouth occlusion pressure and ventilatory response to hypercapnia in patients with chronic obstructive pulmonary disease and pulmonary hypertension.

    Science.gov (United States)

    Corriveau, M L; Shepard, J W; Dolan, G F

    1987-01-01

    Hydralazine has been shown to increase minute ventilation (VE) in patients with chronic obstructive pulmonary disease and pulmonary hypertension. The mechanism by which hydralazine produces this effect has not been defined. We investigated the effects of orally administered hydralazine on hypercapnic ventilatory response (delta VE/delta PaCO2) and central respiratory drive (delta P0.1/delta PaCO2) as well as the effects on hemodynamics, ventilation, and gas exchange in 10 male patients (mean age, 59 +/- 2 yr). The patients had a severe degree of chronic air-flow obstruction (FEV1, 1.07 +/- 0.08 L) and mild pulmonary hypertension (mean pulmonary artery pressure, 25 +/- 4 mm Hg). After hydralazine, the slope of delta VE/delta PaCO2 increased by 177% (p less than 0.005), and the slope of delta P0.1/delta PaCO2 increased by 145% (p less than 0.05). Resting ventilation increased from 14.8 +/- 1.0 to 17.1 +/- 1.4 L/min (p less than 0.02), primarily as a result of increased respiratory frequency. After hydralazine, PaO2 increased from 66 +/- 4 to 70 +/- 3 mm Hg (p less than 0.05) at rest and from 54 +/- 3 to 59 +/- 3 mm Hg (p less than 0.02) during exercise. PaCO2 decreased from 46 +/- 3 to 42 +/- 3 mm Hg (p less than 0.001) at rest and from 50 +/- 3 to 45 +/- 3 mm Hg (p less than 0.001) during exercise. No change was seen in the dead space to tidal volume ratio or the degree of venous admixture. Mean pulmonary artery pressure and total pulmonary resistance both at rest and during exercise were unchanged after hydralazine.(ABSTRACT TRUNCATED AT 250 WORDS)

  15. Continuous Flow Ventilatory Support (Clinical Experience

    Directory of Open Access Journals (Sweden)

    Pavol Török

    2006-01-01

    Full Text Available Background. The world literature contains no reports on the clinical application of continuous flow ventilatory support by an insufflation catheter. Despite the use of different forms of ventilatory support, disconnection of patients from artificial ventilation is unsuccessful in 10—30% of cases despite the fact that the clinical and biochemical criteria are met.Objective: to discuss the efficiency of the new ventilation regime — continuous flow ventilatory support in the clinical setting.Methods: continuous flow ventilatory support with an original licensed multi-jet insufflation catheter or a terminal one-orifice catheter nasally inserted into the trachea was applied to 70 patients. It was used in a subgroup of 64 patients with chronic obstructive lung disease (COLD due to the occurrence of global respiratory insufficiency caused by infectious complications and in a group of 6 patients as a ventilatory regime for their disconnection from long-term artificial ventilation, whose disconnection other ventilatory regimens being used were unsuccessful.Results. None patient with COLD should be intubated, and just 30 minutes after the initiation of ventilatory support with a multi-jet catheter, there were decreases in the mean respiration rate from 33±2.8 to 27±2.5 cycles/min and in paCo2 from 11.9±1.7 to 10.8±1.6 kPa and an increase in paCo2 from 5.7±1.1 to 6.8±1.3 kPa at FiO2 =0.3. Within 24 hours after the initiation of ventilatory support, blood gas levels changed in response to the values typical of partial respiratory insufficiency. The spontaneous ventilation rate decreased to 20±2.2, paCO2 reduced to 6.4±1.2  kPa  and  pO2 continuously  increased  up  to  the  value  8.9±1.4  kPa  (FiO2 =0.3  at  hour  24  of  ventilatory  support. Ventilatory support lasted an average of 5 days. Statistical comparison of the study parameters showed a significant improvement (p<0.05 just 6 hours after ventilatory support and a

  16. OPTIMALITY PRINCIPLE INTEGRATES PLANT RESPONSES TO ELEVATED CO2 AND SOIL NITROGEN AVAILABILITY

    Science.gov (United States)

    Franklin, O.

    2009-12-01

    INTRODUCTION Soil N availability is of particular importance for the response of forests to elevated CO2 (eCO2) because it often limits tree growth responses to eCO2 and changes C allocation among foliage, wood and root systems. Clearly, understanding the interactive effects of eCO2 and soil N availability is essential for accurate projections of forest responses to rising atmospheric CO2. HYPOTHESIS Plants acclimate to soil N availability and atmospheric CO2 by maximizing net growth through three nested optimizations operating on different time scales: short term - vertical canopy N distribution, medium term - Leaf area index (LAI) for a given total canopy N (Nc) and longer term - Nc and root allocation. N uptake is a function of root exploration for N (fine root production) and soil N availability. RESULTS The model explained a range of observed forest CO2 responses of productivity and LAI in FACE experiments (Franklin et al. 2009) (Franklin 2007). N use efficiency increased with soil N availability, which is in line with recent findings regarding resource use efficiency, but contrasts with some earlier conceptual models. The model gives rise to a relationship between root production and total plant N demand, which implies that root production and N uptake is always increased by eCO2 (fig. 1). The increased N uptake associated with increased demand for fine-root production may lead to declining soil N availability (progressive N limitation), which was observed in the ORNL FACE experiment. The principle of maximization of net growth to control allocation could serve as a basis for simplification and generalization of foliage/stem/root allocation in larger scale forest models. REFERENCES Franklin O. (2007) Optimal nitrogen allocation controls tree responses to elevated CO 2. New Phytologist, 174, 811-822 Franklin O., McMurtrie R.E., Iversen C.M., Crous K.Y., Finzi A.C., Tissue D.T., Ellsworth D.S., Oren R. & Norby R.J. (2009) Forest fine-root production and

  17. Plant responses to atmospheric CO2 enrichment with emphasis on roots and the rhizosphere.

    Science.gov (United States)

    Rogers, H H; Runion, G B; Krupa, S V

    1994-01-01

    Empirical records provide incontestable evidence of global changes: foremost among these changes is the rising concentration of CO(2) in the earth's atmosphere. Plant growth is nearly always stimulated by elevation of CO(2). Photosynthesis increases, more plant biomass accumulates per unit of water consumed, and economic yield is enhanced. The profitable use of supplemental CO(2) over years of greenhouse practice points to the value of CO(2) for plant production. Plant responses to CO(2) are known to interact with other environmental factors, e.g. light, temperature, soil water, and humidity. Important stresses including drought, temperature, salinity, and air pollution have been shown to be ameliorated when CO(2) levels are elevated. In the agricultural context, the growing season has been shortened for some crops with the application of more CO(2); less water use has generally, but not always, been observed and is under further study; experimental studies have shown that economic yield for most crops increases by about 33% for a doubling of ambient CO(2) concentration. However, there are some reports of negligible or negative effects. Plant species respond differently to CO(2) enrichment, therefore, clearly competitive shifts within natural communities could occur. Though of less importance in managed agro-ecosystems, competition between crops and weeds could also be altered. Tissue composition can vary as CO(2) increases (e.g. higher C: N ratios) leading to changes in herbivory, but tests of crop products (consumed by man) from elevated CO(2) experiments have generally not revealed significant differences in their quality. However, any CO(2)-induced change in plant chemical or structural make-up could lead to alterations in the plant's interaction with any number of environmental factors-physicochemical or biological. Host-pathogen relationships, defense against physical stressors, and the capacity to overcome resource shortages could be impacted by rises in CO

  18. Elevated-CO2 Response of Stomata and Its Dependence on Environmental Factors

    National Research Council Canada - National Science Library

    Xu, Zhenzhu; Jiang, Yanling; Jia, Bingrui; Zhou, Guangsheng

    2016-01-01

    Stomata control the flow of gases between plants and the atmosphere. This review is centered on stomatal responses to elevated CO2 concentration and considers other key environmental factors and underlying mechanisms at multiple levels...

  19. Growth response of Spirulina platensis PCC9108 to elevated CO2 levels and flue gas

    Directory of Open Access Journals (Sweden)

    Seyedmahdi Hoseini

    2014-01-01

    Full Text Available Introduction: Because their ability to capture CO2, photosynthetical microorganisms have some advantages to CO2 mitigation from high CO2 streams such as flue gases and they can use CO2 as carbon source. Recently, experts have made efforts to exploit microorganisms intended for recovering CO2 from power plants. Materials and methods: To achieve this purpose, we studied the growth response of the cyanobacterium Spirulina platensis PCC9108 under different concentrations of carbon dioxide (ranging from 0.036% to 10% and flue gas in a bench-scale system. Preparation of different concentrations of CO2 and injection into Erlenmeyer flasks was performed by a system including air compressor, CO2 capsule, pressure gauge and flow meter. Results: The main goal of studying this paper is a survey of organism's potential to grow by generated CO2 from flue gas of power plant. It already had the potential and highest biomass production recorded at 8% CO2 (v/v. Also we proved that S.platensis PCC9108 can be grown under flue gas, although biomass production decreased fairly. Total lipid content of algae interestingly enhanced with elevated CO2 levels from ambient air to 4% and 6% which ranged from 14.5 to 15.8 and 16 dry weight (wt. % respectively. In contrast, total protein content illustrated no difference between all treatment and its value was about 46 wt.%. Discussion and conclusion: The results of present study suggested that understudied S.platensis PCC9108 is appropriate for mitigating CO2 because of its carbon fixation ability. Also due to its high protein content, this cyanobacterium is a good candidate to produce SCP (single cell protein.

  20. Responses of the marine diatom Thalassiosira pseudonana to changes in CO2 concentration: a proteomic approach.

    Science.gov (United States)

    Clement, Romain; Lignon, Sabrina; Mansuelle, Pascal; Jensen, Erik; Pophillat, Matthieu; Lebrun, Regine; Denis, Yann; Puppo, Carine; Maberly, Stephen C; Gontero, Brigitte

    2017-02-09

    The concentration of CO2 in many aquatic systems is variable, often lower than the KM of the primary carboxylating enzyme Rubisco, and in order to photosynthesize efficiently, many algae operate a facultative CO2 concentrating mechanism (CCM). Here we measured the responses of a marine diatom, Thalassiosira pseudonana, to high and low concentrations of CO2 at the level of transcripts, proteins and enzyme activity. Low CO2 caused many metabolic pathways to be remodeled. Carbon acquisition enzymes, primarily carbonic anhydrase, stress, degradation and signaling proteins were more abundant while proteins associated with nitrogen metabolism, energy production and chaperones were less abundant. A protein with similarities to the Ca(2+)/ calmodulin dependent protein kinase II_association domain, having a chloroplast targeting sequence, was only present at low CO2. This protein might be a specific response to CO2 limitation since a previous study showed that other stresses caused its reduction. The protein sequence was found in other marine diatoms and may play an important role in their response to low CO2 concentration.

  1. INTERACTION BETWEEN DELTA OPIOID RECEPTORS AND BENZODIAZEPINES IN CO2- INDUCED RESPIRATORY RESPONSES IN MICE

    Science.gov (United States)

    Borkowski, Anne H.; Barnes, Dylan C.; Blanchette, Derek R.; Castellanos, F. Xavier; Klein, Donald F.; Wilson, Donald A.

    2011-01-01

    The false-suffocation hypothesis of panic disorder (Klein, 1993) suggested δ-opioid receptors as a possible source of the respiratory dysfunction manifested in panic attacks occurring in panic disorder (Preter and Klein, 2008). This study sought to determine if a lack of δ-opioid receptors in a mouse model affects respiratory response to elevated CO2, and whether the response is modulated by benzodiazepines, which are widely used to treat panic disorder. In a whole-body plethysmograph, respiratory responses to 5% CO2 were compared between δ-opioid receptor knockout mice and wild-type mice after saline, diazepam (1 mg/kg), and alprazolam (0.3 mg/kg) injection. The results show that lack of δ-opioid receptors does not affect normal response to elevated CO2, but does prevent benzodiazepines from modulating that response. Thus, in the presence of benzodiazepine agonists, respiratory responses to elevated CO2 were enhanced in δ-opioid receptor knockout mice compared to wild-type mice. This suggests an interplay between benzodiazepine receptors and δ-opioid receptors in regulating the respiratory effects of elevated CO2, which might be related to CO2 induced panic. PMID:21561601

  2. Variation in Yield Responses to Elevated CO2 and a Brief High Temperature Treatment in Quinoa

    Science.gov (United States)

    Bunce, James A.

    2017-01-01

    Intraspecific variation in crop responses to global climate change conditions would provide opportunities to adapt crops to future climates. These experiments explored intraspecific variation in response to elevated CO2 and to high temperature during anthesis in Chenopodium quinoa Wild. Three cultivars of quinoa were grown to maturity at 400 (“ambient”) and 600 (“elevated”) μmol·mol−1 CO2 concentrations at 20/14 °C day/night (“control”) temperatures, with or without exposure to day/night temperatures of 35/29 °C (“high” temperatures) for seven days during anthesis. At control temperatures, the elevated CO2 concentration increased the total aboveground dry mass at maturity similarly in all cultivars, but by only about 10%. A large down-regulation of photosynthesis at elevated CO2 occurred during grain filling. In contrast to shoot mass, the increase in seed dry mass at elevated CO2 ranged from 12% to 44% among cultivars at the control temperature. At ambient CO2, the week-long high temperature treatment greatly decreased (0.30 × control) or increased (1.70 × control) seed yield, depending on the cultivar. At elevated CO2, the high temperature treatment increased seed yield moderately in all cultivars. These quinoa cultivars had a wide range of responses to both elevated CO2 and to high temperatures during anthesis, and much more variation in harvest index responses to elevated CO2 than other crops that have been examined. PMID:28678208

  3. Variation in Yield Responses to Elevated CO2 and a Brief High Temperature Treatment in Quinoa

    Directory of Open Access Journals (Sweden)

    James A. Bunce

    2017-07-01

    Full Text Available Intraspecific variation in crop responses to global climate change conditions would provide opportunities to adapt crops to future climates. These experiments explored intraspecific variation in response to elevated CO2 and to high temperature during anthesis in Chenopodium quinoa Wild. Three cultivars of quinoa were grown to maturity at 400 (“ambient” and 600 (“elevated” μmol·mol−1 CO2 concentrations at 20/14 °C day/night (“control” temperatures, with or without exposure to day/night temperatures of 35/29 °C (“high” temperatures for seven days during anthesis. At control temperatures, the elevated CO2 concentration increased the total aboveground dry mass at maturity similarly in all cultivars, but by only about 10%. A large down-regulation of photosynthesis at elevated CO2 occurred during grain filling. In contrast to shoot mass, the increase in seed dry mass at elevated CO2 ranged from 12% to 44% among cultivars at the control temperature. At ambient CO2, the week-long high temperature treatment greatly decreased (0.30 × control or increased (1.70 × control seed yield, depending on the cultivar. At elevated CO2, the high temperature treatment increased seed yield moderately in all cultivars. These quinoa cultivars had a wide range of responses to both elevated CO2 and to high temperatures during anthesis, and much more variation in harvest index responses to elevated CO2 than other crops that have been examined.

  4. Germination of CO2-enriched Pinus taeda L. seeds and subsequent seedling growth responses to CO2 enrichment

    Science.gov (United States)

    M. Hussain; M. E. Kubiske; K. F. Connor

    2001-01-01

    Increasing atmospheric carbon dioxide concentration, [CO2], has profound effects on growth and development of trees. Adoubling of [C02] generally stimulates photosynthesis (Murray 1995; Saxe, Ellsworth & Heath 1998) and can lead to a substantial increase in tree growth (Poorter 1993). For example, doubling [C0

  5. Belowground heathland responses after 2 years of combined warming, elevated CO2 and summer drought

    DEFF Research Database (Denmark)

    Andresen, Louise C.; Michelsen, Anders; Ambus, Per

    2010-01-01

    Terrestrial ecosystems are exposed to atmospheric and climatic changes including increases in atmospheric CO2 concentration, temperature and alterations of precipitation patterns, which are predicted to continue with consequences for ecosystem services and functioning in the future. In a field sc...... and periodic drought did not unambiguously express the ecosystem responses of single factors additively, which complicates predictions of ecosystem responses to multifactor climate change.......Terrestrial ecosystems are exposed to atmospheric and climatic changes including increases in atmospheric CO2 concentration, temperature and alterations of precipitation patterns, which are predicted to continue with consequences for ecosystem services and functioning in the future. In a field...... (1 year after 13C215N-glycine was injected into the soil) increased in warmed plots and in elevated CO2 plots, but not when these treatments were combined. Furthermore, drought led to an increase in Calluna biomass and total plant nitrogen pool. The full combination of warming, elevated CO2...

  6. Serotonin nerve terminals in the dorsomedial medulla facilitate sympathetic and ventilatory responses to hemorrhage and peripheral chemoreflex activation.

    Science.gov (United States)

    Kung, Ling-Hsuan; Scrogin, Karie E

    2011-11-01

    Serotonin neurons of the caudal raphe facilitate ventilatory and sympathetic responses that develop following blood loss in conscious rats. Here, we tested whether serotonin projections to the caudal portion of the dorsomedial brain stem (including regions of the nucleus tractus solitarius that receive cardiovascular and chemosensory afferents) contribute to cardiorespiratory compensation following hemorrhage. Injections of the serotonin neurotoxin 5,7-dihydroxytryptamine produced >90% depletion of serotonin nerve terminals in the region of injection. Withdrawal of ∼21% of blood volume over 10 min produced a characteristic three-phase response that included 1) a normotensive compensatory phase, 2) rapid sympathetic withdrawal and hypotension, and 3) rapid blood pressure recovery accompanied by slower recovery of heart rate and sympathetic activity. A gradual tachypnea developed throughout hemorrhage, which quickly reversed with the advent of sympathetic withdrawal. Subsequently, breathing frequency and neural minute volume (determined by diaphragmatic electromyography) declined below baseline following termination of hemorrhage but gradually recovered over time. Lesioned rats showed attenuated sympathetic and ventilatory responses during early compensation and later recovery from hemorrhage. Both ventilatory and sympathetic responses to chemoreceptor activation with potassium cyanide injection were attenuated by the lesion. In contrast, the gain of sympathetic and heart rate baroreflex responses was greater, and low-frequency oscillations in blood pressure were reduced after lesion. Together, the data are consistent with the view that serotonin innervation of the caudal dorsomedial brain stem contributes to sympathetic compensation during hypovolemia, possibly through facilitation of peripheral chemoreflex responses.

  7. The hypoxic ventilatory response and ventilatory long-term facilitation are altered by time of day and repeated daily exposure to intermittent hypoxia

    Science.gov (United States)

    Gerst, David G.; Yokhana, Sanar S.; Carney, Laura M.; Lee, Dorothy S.; Badr, M. Safwan; Qureshi, Tabarak; Anthouard, Magalie N.

    2011-01-01

    This study examined whether time of day and repeated exposure to intermittent hypoxia have an impact on the hypoxic ventilatory response (HVR) and ventilatory long-term facilitation (vLTF). Thirteen participants with sleep apnea were exposed to twelve 4-min episodes of isocapnic hypoxia followed by a 30-min recovery period each day for 10 days. On days 1 (initial day) and 10 (final day) participants completed the protocol in the evening (PM); on the remaining days the protocol was completed in the morning (AM). The HVR was increased in the morning compared with evening on the initial (AM 0.83 ± 0.08 vs. PM 0.64 ± 0.11 l·min−1·%SaO2−1; P ≤ 0.01) and final days (AM 1.0 ± 0.08 vs. PM 0.81 ± 0.09 l·min−1·%SaO2−1; P ≤ 0.01, where %SaO2 refers to percent arterial oxygen saturation). Moreover, the magnitude of the HVR was enhanced following daily exposure to intermittent hypoxia in the morning (initial day 0.83 ± 0.08 vs. final day 1.0 ± 0.08 l·min−1·%SaO2−1; P ≤ 0.03) and evening (initial day 0.64 ± 0.11 vs. final day 0.81 ± 0.09 l·min−1·%SaO2−1; P ≤ 0.03). vLTF was reduced in the morning compared with the evening on the initial (AM 19.03 ± 0.35 vs. PM 22.30 ± 0.49 l/min; P ≤ 0.001) and final (AM 20.54 ± 0.32 vs. PM 23.11 ± 0.54 l/min; P ≤ 0.01) days. Following daily exposure to intermittent hypoxia, vLTF was enhanced in the morning (initial day 19.03 ± 0.35 vs. final day 20.54 ± 0.32 l/min; P ≤ 0.01). We conclude that the HVR is increased while vLTF is decreased in the morning compared with the evening in individuals with sleep apnea and that the magnitudes of these phenomena are enhanced following daily exposure to intermittent hypoxia. PMID:20724571

  8. Responses of soil CO(2) efflux to precipitation pulses in two subtropical forests in southern China.

    Science.gov (United States)

    Deng, Qi; Zhou, Guoyi; Liu, Shizhong; Chu, Guowei; Zhang, Deqiang

    2011-12-01

    This study was designed to examine the responses of soil CO(2) efflux to precipitation pulses of varying intensities using precipitation simulations in two subtropical forests [i.e., mixed and broadleaf forests (MF and BF)] in southern China. The artificial precipitation event was achieved by spraying a known amount of water evenly in a plot (50 × 50 cm(2)) over a 30 min period, with intensities ranging from 10, 20, 50 and 100 mm within the 30 min. The various intensities were simulated in both dry season (in December 2007) and wet (in May 2008) season. We characterized the dynamic patterns of soil CO(2) efflux rate and environmental factors over the 5 h experimental period. Results showed that both soil moisture and soil CO(2) efflux rate increased to peak values for most of the simulated precipitation treatments, and gradually returned to the pre-irrigation levels after irrigation in two forests. The maximum peak of soil CO(2) efflux rate occurred at the 10 mm precipitation event in the dry season in BF and was about 3.5 times that of the pre-irrigation value. The change in cumulative soil CO(2) efflux following precipitation pulses ranged from -0.68 to 1.72 g CO(2) m(-2) over 5 h compared to the pre-irrigation levels and was generally larger in the dry season than in the wet season. The positive responses of soil CO(2) efflux to precipitation pulses declined with the increases in precipitation intensity, and surprisingly turned to negative when precipitation intensity reached 50 and 100 mm in the wet season. These findings indicated that soil CO(2) efflux could be changed via pulse-like fluxes in subtropical forests in southern China as fewer but extreme precipitation events occur in the future.

  9. Anterior cerebral blood velocity and end-tidal CO2 responses to exercise differ in children and adults.

    Science.gov (United States)

    Ellis, Lindsay A; Ainslie, Philip N; Armstrong, Victoria A; Morris, Laura E; Simair, Ryan G; Sletten, Nathan R; Tallon, Christine M; McManus, Ali M

    2017-06-01

    Little is known about the response of the cerebrovasculature to acute exercise in children and how these responses might differ with adults. Therefore, we compared changes in middle cerebral artery blood velocity (MCAVmean), end-tidal Pco2 ([Formula: see text]), blood pressure, and minute ventilation (V̇e) in response to incremental exercise between children and adults. Thirteen children [age: 9 ± 1 (SD) yr] and thirteen sex-matched adults (age: 25 ± 4 yr) completed a maximal exercise test, during which MCAVmean, [Formula: see text], and V̇e were measured continuously. These variables were measured at rest, at exercise intensities specific to individual ventilatory thresholds, and at maximum. Although MCAVmean was higher at rest in children compared with adults, there were smaller increases in children (1-12%) compared with adults (12-25%) at all exercise intensities. There were alterations in [Formula: see text] with exercise intensity in an age-dependent manner [F(2.5,54.5) = 7.983, P 0.05) until hyperventilation-induced reductions following the respiratory compensation point. In adults, [Formula: see text] increased with exercise intensity (36-45 mmHg, P adults showed a greater hyperventilation-induced hypocapnia than children. These findings show that the relative increase in MCAVmean during exercise was attenuated in children compared with adults. There was also a weaker relationship between MCAVmean and [Formula: see text] during exercise in children, suggesting that cerebral perfusion may be regulated by different mechanisms during exercise in the child.NEW & NOTEWORTHY These findings provide the first direct evidence that exercise increases cerebral blood flow in children to a lesser extent than in adults. Changes in end-tidal CO2 parallel changes in cerebral perfusion in adults but not in children, suggesting age-dependent regulatory mechanisms of cerebral blood flow during exercise. Copyright © 2017 the American Physiological Society.

  10. [CO2 response process and its simulation of Prunus sibirica photosynthesis under different soil moisture conditions].

    Science.gov (United States)

    Wu, Qin; Zhang, Guang-Can; Pei, Bin; Xu, Zhi-Qiang; Zhao, Yu; Fang, Li-Dong

    2013-06-01

    Taking the two-year old potted Prunus sibirica seedlings as test materials, and using CIRAS-2 photosynthetic system, this paper studied the CO2 response process of P. sibirica photosynthesis in semi-arid loess hilly region under eight soil moisture conditions. The CO2 response data of P. sibirica were fitted and analyzed by rectangular hyperbola model, exponential equation, and modified rectangular hyperbola model. Meanwhile, the quantitative relationships between the photosynthesis and the soil moisture were discussed. The results showed that the CO2 response process of P. sibirica photosynthesis had obvious response characteristics to the soil moisture threshold. The relative soil water content (RWC) required to maintain the higher photosynthetic rate (P(n)) and carboxylation efficiency (CE) of P. sibirica was in the range of 46.3%-81.9%. In this RWC range, the photosynthesis did not appear obvious CO2 saturated inhibition phenomenon. When the RWC exceeded this range, the photosynthetic capacity (P(n max)), CE, and CO2 saturation point (CSP) decreased evidently. Under different soil moisture conditions, there existed obvious differences among the three models in simulating the CO2 response data of P. sibirica. When the RWC was in the range of 46.3%-81.9%, the CO2 response process and the characteristic parameters such as CE, CO2 compensation point (see symbol), and photorespiration rate (R(p)) could be well fitted by the three models, and the accuracy was in the order of modified rectangular hyperbola model > exponential equation > rectangular hyperbola model. When the RWC was too high or too low, namely, the RWC was > 81.9% or process and the characteristic parameters. It was suggested that when the RWC was from 46.3% to 81.9%, the photosynthetic efficiency of P. sibirica was higher, and, as compared with rectangular hyperbola model and exponential equation, modified rectangular hyperbola model had more applicability to fit the CO2 response data of P. sibirica

  11. Younger Dryas cooling and the Greenland climate response to CO2.

    Science.gov (United States)

    Liu, Zhengyu; Carlson, Anders E; He, Feng; Brady, Esther C; Otto-Bliesner, Bette L; Briegleb, Bruce P; Wehrenberg, Mark; Clark, Peter U; Wu, Shu; Cheng, Jun; Zhang, Jiaxu; Noone, David; Zhu, Jiang

    2012-07-10

    Greenland ice-core δ(18)O-temperature reconstructions suggest a dramatic cooling during the Younger Dryas (YD; 12.9-11.7 ka), with temperatures being as cold as the earlier Oldest Dryas (OD; 18.0-14.6 ka) despite an approximately 50 ppm rise in atmospheric CO(2). Such YD cooling implies a muted Greenland climate response to atmospheric CO(2), contrary to physical predictions of an enhanced high-latitude response to future increases in CO(2). Here we show that North Atlantic sea surface temperature reconstructions as well as transient climate model simulations suggest that the YD over Greenland should be substantially warmer than the OD by approximately 5 °C in response to increased atmospheric CO(2). Additional experiments with an isotope-enabled model suggest that the apparent YD temperature reconstruction derived from the ice-core δ(18)O record is likely an artifact of an altered temperature-δ(18)O relationship due to changing deglacial atmospheric circulation. Our results thus suggest that Greenland climate was warmer during the YD relative to the OD in response to rising atmospheric CO(2), consistent with sea surface temperature reconstructions and physical predictions, and has a sensitivity approximately twice that found in climate models for current climate due to an enhanced albedo feedback during the last deglaciation.

  12. Stomatal Responses to CO(2) in Paphiopedilum and Phragmipedium: Role of the Guard Cell Chloroplast.

    Science.gov (United States)

    Assmann, S M; Zeiger, E

    1985-02-01

    A role of the guard cell chloroplasts in the CO(2) response of stomata was investigated through a comparison of the leaf gas exchange characteristics of two closely related orchids: Paphiopedilum harrisianum, which lacks guard cell chloroplasts and Phragmipedium longifolium, which has chlorophyllous guard cells. Leaves of both species had an apparent quantum yield for assimilation of about 0.05, with photosynthesis saturating at 0.300 to 0.400 millimoles per square meter per second. CO(2) curves were obtained by measuring steady-state assimilation and stomatal conductance under 0.180 or 0.053 millimoles per square meter per second white light, or darkness, at 0 to 400 microliters per liter ambient CO(2). The response of assimilation to changes in CO(2) was similar in the two species, but the response of conductance was consistently weaker in Paphiopedilum than in Phragmipedium. The data suggest involvement of guard cell chloroplasts in the stomatal response to CO(2) and in the coupling of assimilation and conductance in the intact leaf.

  13. Ventilatory response at the onset of voluntary exercise and passive movement in endurance runners.

    Science.gov (United States)

    Miyamura, M; Ishida, K; Hashimoto, I; Yuza, N

    1997-01-01

    The present study was performed to examine whether or not the ventilatory response at the onset of voluntary exercise and passive movement in endurance runners is the same as in untrained subjects. Twelve long-distance runners belonging to the varsity athletic club and 13 untrained subjects of our university participated as subjects in this study. Maximum oxygen uptake was significantly higher in the endurance runner group [mean (SD) 70.8 (4.7) ml.kg-1.min-1] than in the untrained group [49.8 (6.3) ml.kg-1.min-1]. Cardiorespiratory responses during voluntary exercise and passive movement of alternate flexion-extension of the right and left legs for about 15 s at a frequency of about 60 rpm, were determined by means of breath-by-breath techniques. Minute inspiratory ventilation (VI), tidal volume (VT), respiratory frequency (fb), cardiac output (Qc), stroke volume (SV) and heart rate (HR) increased significantly immediately at the onset of voluntary exercise and passive movement. The incremental rate for VI was greater than that for Qc. Average values and standard deviations of changes in VI were calculated as the difference between the mean of the first and second breath and the mean of five breaths preceding the exercise or movement. The rates obtained in voluntary exercise and passive movement in the endurance runner group [2.34 (0.82) and 1.72 (0.71 l.min-1), respectively] were significantly (P untrained group [4.16 (2.66) and 2.71 (1.56 l.min-1), respectively]. Also changes in VT and HR were significantly lower in the endurance group than in the untrained group with regard to both voluntary exercise and passive movement. The results suggest that the magnitude of cardiorespiratory responses at the onset of voluntary exercise and passive movement in humans is influenced by chronic endurance training for long periods.

  14. Growth and photosynthetic responses of the cordgrass Spartina maritima to CO2 enrichment and salinity.

    Science.gov (United States)

    Mateos-Naranjo, E; Redondo-Gómez, S; Andrades-Moreno, L; Davy, A J

    2010-10-01

    Future climatic scenarios combine increasing concentrations of atmospheric CO(2) and rising sea levels. Spartina maritima is a C(4) halophyte that is an important pioneer and ecosystem engineer in salt marshes of the Atlantic coast of southern Europe. A glasshouse experiment investigated the combined effects on its growth and photosynthetic apparatus of approximately doubling CO(2) concentration (from 380 to 700 μmol mol(-1)) at a range of salinity (0, 171 and 510 mM NaCl). We measured relative growth rates, gas exchange, chlorophyll fluorescence parameters, photosynthetic pigment concentrations, and total ash, Na(+), K(2+), Ca(2+) and N concentrations. Elevated CO(2) stimulated growth of S. maritima by c. 65% at all external salinities; this growth enhancement was associated with greater net photosynthetic rate (A) and improved leaf water relations. A increased despite a drop in stomatal conductance in response to 700 μmol mol(-1) CO(2). CO(2) and salinity had a marked overall effect on the photochemical (PSII) apparatus and the synthesis of photosynthetic pigments. Φ(PSII) values at midday decreased significantly with external salinity in plants grown at 380 μmol mol(-1) CO(2); and F(v)/F(m) and Φ(PSII) values were higher at 700 μmol mol(-1) CO(2) in presence of NaCl. Plant nutrient concentrations declined under elevated CO(2), which can be ascribed to the dilution effect caused by an increase in biomass. The results suggest that the productivity S. maritima and the ecosystem services it provides will increase in likely future climatic scenarios. Copyright © 2010 Elsevier Ltd. All rights reserved.

  15. Assessment of ventilatory neuromuscular drive in patients with obstructive sleep apnea

    Directory of Open Access Journals (Sweden)

    L.R.A. Bittencourt

    1998-04-01

    Full Text Available The presence of abnormalities of the respiratory center in obstructive sleep apnea (OSA patients and their correlation with polysomnographic data are still a matter of controversy. Moderately obese, sleep-deprived OSA patients presenting daytime hypersomnolence, with normocapnia and no clinical or spirometric evidence of pulmonary disease, were selected. We assessed the ventilatory control and correlated it with polysomnographic data. Ventilatory neuromuscular drive was evaluated in these patients by measuring the ventilatory response (VE, the inspiratory occlusion pressure (P.1 and the ventilatory pattern (VT/TI, TI/TTOT at rest and during submaximal exercise, breathing room air. These analyses were also performed after inhalation of a hypercapnic mixture of CO2 (DP.1/DPETCO2, DVE/DPETCO2. Average rest and exercise ventilatory response (VE: 12.2 and 32.6 l/min, respectively, inspiratory occlusion pressure (P.1: 1.5 and 4.7 cmH2O, respectively, and ventilatory pattern (VT/TI: 0.42 and 1.09 l/s; TI/TTOT: 0.47 and 0.46 l/s, respectively were within the normal range. In response to hypercapnia, the values of ventilatory response (DVE/DPETCO2: 1.51 l min-1 mmHg-1 and inspiratory occlusion pressure (DP.1/DPETCO2: 0.22 cmH2O were normal or slightly reduced in the normocapnic OSA patients. No association or correlation between ventilatory neuromuscular drive and ventilatory pattern, hypersomnolence score and polysomnographic data was found; however a significant positive correlation was observed between P.1 and weight. Our results indicate the existence of a group of normocapnic OSA patients who have a normal awake neuromuscular ventilatory drive at rest or during exercise that is partially influenced by obesity

  16. Optimisation modelling predicts leaf trait variation and response to elevated CO2

    Science.gov (United States)

    Pepper, D. A.; McMurtrie, R. E.; Norby, R. J.

    2009-12-01

    The capacities of a plant to obtain the resources it requires and the efficiencies of use of those resources are important determinants of the rate of plant carbon production. Such capacities and efficiencies rely strongly on plant traits, across all relevant scales of plant function (molecular to whole plant). Within inherent (genetic) constraints to the expression of plant traits by any one plant species, a plant would do well to adjust its traits in such a way as to maximise production. We test this hypothesis using a simple plant carbon-nitrogen model applied to a free-air CO2 enrichment (FACE) experiment on sweetgum forest at Oak Ridge, Tennessee, USA. The sweetgum (Liquidambar styraciflua) stand, exposed to ambient atmospheric CO2 or air enriched with CO2 to 550 ppm since 1998, has shown a positive response of net primary productivity (NPP) to elevated CO2 compared to the ambient control. Experiments like this one have been conducted to gauge the response of the biosphere to the significant increase in atmospheric CO2 concentration. In this study we use optimisation modelling to maximise photosynthetic nitrogen use efficiency and output corresponding optimal leaf traits, including (on a per unit leaf area basis): leaf nitrogen content (N), leaf mass (LMA), maximum rate of CO2 assimilation (Amax), average rate of CO2 assimilation (A), and leaf respiration (R). The optimal leaf traits change under a diminishing light level with canopy depth. Integration over canopy depth provides an estimate of canopy total carbon (carbon allocated to leaves), carbon production, canopy carbon export (carbon allocation to wood, fine roots and reproductive structures), and plant N demand to support a canopy comprised of optimal leaves. Thus, simulated plant N demand depends on leaf traits and light level. When simulated plant N demand exceeds N availability, leaf area adjustment occurs, which has impacts on canopy total carbon, carbon production, and canopy carbon export (plant

  17. Response of Heterogeneous and Fractured Carbonate Samples to CO2-Brine Exposure

    Science.gov (United States)

    Smith, M. M.; Mason, H. E.; Hao, Y.; Carroll, S.

    2014-12-01

    Carbonate rock units are often considered as candidate sites for storage of carbon dioxide (CO2), whether as stand-alone reservoirs or coupled with enhanced oil recovery efforts. In order to accept injected carbon dioxide, carbonate reservoirs must either possess sufficient preexisting connected void space, or react with CO2-acidified fluids to produce more pore space and improve permeability. However, upward migration of CO2 through barrier zones or seal layers must be minimized for effective safe storage. Therefore, prediction of the changes to porosity and permeability in these systems over time is a key component of reservoir management. Towards this goal, we present the results of several experiments on carbonate core samples from the Wellington, Kansas 1-32 well, conducted under reservoir temperature, pressure, and CO2 conditions. These samples were imaged by X-ray computed tomography (XRCT) and analyzed with nuclear magnetic resonance (NMR) spectroscopy both prior to and after reaction with CO2-enriched brines. The carbonate samples each displayed distinct responses to CO2 exposure in terms of permeability change with time and relative abundance of calcite versus dolomite dissolution. The measured permeability of each sample was also much lower than that estimated by downhole NMR logging, with samples with larger fractured regions possessing higher permeability values. We present also our modeling approach and preliminary simulation results for a specific sample from the targeted injection zone. The heterogeneous composition as well as the presence of large fractured zones within the rock necessitated the use of a nested three-region approach to represent the range of void space observed via tomography. Currently, the physical response to CO2-brine flow (i.e., pressure declines with time) is reproduced well but the extent of chemical reaction is overestimated by the model.

  18. A multi-biome gap in understanding of crop and ecosystem responses to elevated CO2.

    Science.gov (United States)

    Leakey, Andrew D B; Bishop, Kristen A; Ainsworth, Elizabeth A

    2012-06-01

    A key finding from elevated [CO(2)] field experiments is that the impact of elevated [CO(2)] on plant and ecosystem function is highly dependent upon other environmental conditions, namely temperature and the availability of nutrients and soil moisture. In addition, there is significant variation in the response to elevated [CO(2)] among plant functional types, species and crop varieties. However, experimental data on plant and ecosystem responses to elevated [CO(2)] are strongly biased to economically and ecologically important systems in the temperate zone. There is a multi-biome gap in experimental data that is most severe in the tropics and subtropics, but also includes high latitudes. Physiological understanding of the environmental conditions and species found at high and low latitudes suggest they may respond differently to elevated [CO(2)] than well-studied temperate systems. Addressing this knowledge gap should be a high priority as it is vital to understanding 21st century food supply and ecosystem feedbacks on climate change. Published by Elsevier Ltd.

  19. Unique responsiveness of angiosperm stomata to elevated CO2 explained by calcium signalling.

    Directory of Open Access Journals (Sweden)

    Timothy J Brodribb

    Full Text Available Angiosperm and conifer tree species respond differently when exposed to elevated CO2, with angiosperms found to dynamically reduce water loss while conifers appear insensitive. Such distinct responses are likely to affect competition between these tree groups as atmospheric CO2 concentration rises. Seeking the mechanism behind this globally important phenomenon we targeted the Ca(2+-dependent signalling pathway, a mediator of stomatal closure in response to elevated CO2, as a possible explanation for the differentiation of stomatal behaviours. Sampling across the diversity of vascular plants including lycophytes, ferns, gymnosperms and angiosperms we show that only angiosperms possess the stomatal behaviour and prerequisite genetic coding, linked to Ca(2+-dependent stomatal signalling. We conclude that the evolution of Ca(2+-dependent stomatal signalling gives angiosperms adaptive benefits in terms of highly efficient water use, but that stomatal sensitivity to high CO2 may penalise angiosperm productivity relative to other plant groups in the current era of soaring atmospheric CO2.

  20. Modeling forest C and N allocation responses to free-air CO2 enrichment

    Science.gov (United States)

    Luus, Kristina; De Kauwe, Martin; Walker, Anthony; Werner, Christian; Iversen, Colleen; McCarthy, Heather; Medlyn, Belinda; Norby, Richard; Oren, Ram; Zak, Donald; Zaehle, Sönke

    2015-04-01

    Vegetation allocation patterns and soil-vegetation partitioning of C and N are predicted to change in response to rising atmospheric concentrations of CO2. These allocation responses to rising CO2 have been examined at the ecosystem level through through free-air CO2 enrichment (FACE) experiments, and their global implications for the timing of progressive N limitation (PNL) and C sequestration have been predicted for ~100 years using a variety of ecosystem models. However, recent FACE model-data syntheses studies [1,2,3] have indicated that ecosystem models do not capture the 5-10 year site-level ecosystem allocation responses to elevated CO2. This may be due in part to the missing representation of the rhizosphere interactions between plants and soil biota in models. Ecosystem allocation of C and N is altered by interactions between soil and vegetation through the priming effect: as plant N availability diminishes, plants respond physiologically by altering their tissue allocation strategies so as to increase rates of root growth and rhizodeposition. In response, either soil organic material begins to accumulate, which hastens the onset of PNL, or soil microbes start to decompose C more rapidly, resulting in increased N availability for plant uptake, which delays PNL. In this study, a straightforward approach for representing rhizosphere interactions in ecosystem models was developed through which C and N allocation to roots and rhizodeposition responds dynamically to elevated CO2 conditions, modifying soil decomposition rates without pre-specification of the direction in which soil C and N accumulation should shift in response to elevated CO2. This approach was implemented in a variety of ecosystem models ranging from stand (G'DAY), to land surface (CLM 4.5, O-CN), to dynamic global vegetation (LPJ-GUESS) models. Comparisons against data from three forest FACE sites (Duke, Oak Ridge & Rhinelander) indicated that representing rhizosphere interactions allowed

  1. The growth response of plants to elevated CO2 under non-optimal environmental conditions.

    Science.gov (United States)

    Poorter, Hendrik; Pérez-Soba, Marta

    2001-09-01

    strongly increased, to the extent that high CO2 even compensated in an absolute way for the harmful effect of ozone on growth. No systematic difference in response was found between herbaceous and woody species for any of the environmental variables considered.

  2. Ventilatory Response to Hypercapnia Predicts Dementia with Lewy Bodies in Late-Onset Major Depressive Disorder.

    Science.gov (United States)

    Takahashi, Sho; Mizukami, Katsuyoshi; Arai, Tetsuaki; Ogawa, Ryoko; Kikuchi, Norihiro; Hattori, Satoshi; Darby, David; Asada, Takashi

    2016-01-01

    Studies have shown that developing major depressive disorder (MDD) at 50 years of age or older can predict dementia. Depression is particularly common in dementia with Lewy bodies (DLB), and occasionally occurs before the onset of extrapyramidal symptoms. Moreover, systemic autonomic dysfunction, including an abnormal ventilatory response to hypercapnia (VRH), is common in patients with DLB. Here, we aimed to determine whether the VRH is useful for distinguishing depression that is predictive of DLB from other types of MDD. Participants were 35 consecutive patients with first onset MDD at 50 years or older with bradykinesia. After diagnosing the clinical subtype of MDD according to DSM-IV criteria, each subject underwent a battery of psychological tests, autonomic examinations including VRH, brain magnetic resonance imaging, and 123I-meta-iodobenzylguanidine scintigraphy. Longitudinal follow-up showed that all 18 patients with abnormal VRH results developed DLB, whereas none of the 17 patients with normal VRH results converted to DLB within the study period (sensitivity: 100% , specificity: 100%). Additionally, over half of the DLB converters showed abnormalities on other autonomic examinations. For converters, the most common MDD subtype had psychotic and melancholic features simultaneously. The frequency of hypersensitivity to psychotropics was higher in converters than it was in non-converters. In the present study, patients with abnormal VRH results were very likely to develop DLB. Thus, for patients with late-onset MDD accompanied by bradykinesia, the VRH in combination with the clinical subtype of MDD or hypersensitivity to psychotropics may be useful for diagnosing prodromal DLB.

  3. Simulatd Nitrogen Cycling Response to Elevated CO2 in Pinus taeda and Mixed Dediduous Forests

    Science.gov (United States)

    D.W. Johnson

    1999-01-01

    Interactions between elevated CO2 and N cycling were explored with a nutrient cycling model (NuCM, Johnson et al. 1993, 1995) for a Pinus tuedu L. site at Duke University North Carolina, and a mixed deciduous site at Walker Branch, Tennessee. The simulations tested whether N limitation would prevent growth increases in response to elevated CO...

  4. Response to elevated CO 2 from a natural spring in a C 4 ...

    African Journals Online (AJOL)

    ... the late season. CO2-responsiveness in the field generally followed the seasonal phenologies of each species, being greatest during the most active growth period. Keywords: climate change; gas exchange; photosynthetic regulation; stomatal conductance. African Journal of Range & Forage Science: 2002 19(2): 81-91 ...

  5. Detection of elevated CO 2 responsive QTLs for yield and its ...

    African Journals Online (AJOL)

    Transgressive segregation and continuous distribution in the CSSLs were observed for elevated CO2 response values (the value in FACE minus that in Ambient), in panicle number per plant (PN), grain number per panicle (GN), 1000 grain weight (GW) and yield per plant (YD), suggesting that all the tested traits responding ...

  6. Temperature response of biological materials to pulsed non-ablative CO2 laser irradiation

    NARCIS (Netherlands)

    Brugmans, M. J.; Kemper, J.; Gijsbers, G. H.; van der Meulen, F. W.; van Gemert, M. J.

    1991-01-01

    This paper presents surface temperature responses of various tissue phantoms and in vitro and in vivo biological materials in air to non-ablative pulsed CO2 laser irradiation, measured with a thermocamera. We studied cooling off behavior of the materials after a laser pulse, to come to an

  7. Seed vigor of contrasting rice cutivars in response to rising CO2

    Science.gov (United States)

    Although a number of studies have shown that rising atmospheric carbon dioxide concentration, [CO2], can differentially affect the growth and yield potential of rice (Oryza sativa L.) cultivars, there has been no attempt to determine if the response is associated with changes in seed vigor, an essen...

  8. The influence of the stratosphere on the tropospheric zonal wind response to CO2 doubling

    NARCIS (Netherlands)

    Hinssen, Y.B.L.; Bell, C.J.; Siegmund, P.C.

    2011-01-01

    The influence of a CO2 doubling on the stratospheric potential vorticity (PV) is examined in two climate models. Subsequently, the influence of changes in the stratosphere on the tropospheric zonal wind response is investigated, by inverting the stratospheric PV. Radiative effects seem to dominate

  9. Synthesis of Scrub-Oak Ecosystem Responses to Elevated CO2

    Energy Technology Data Exchange (ETDEWEB)

    Hungate, Bruce

    2014-11-07

    This report summarizes a synthesis project of a long-term global change experiment conducted at the Kennedy Space Center, Florida, investigating how increasing concentrations of atmospheric carbon dioxide (CO2) influences the functioning of a fire-dominated scrub-oak ecosystem. The experiment began in 1996 and ended in 2007. Results presented here summarize the effects of elevated CO2 on plant growth, soil processes, carbon and nutrient cycling, and other responses. Products include archived data from the experiment, as well as six publications in the peer-reviewed literature.

  10. Comparison of equilibrium and transient responses to CO2 increase in eight state-of-the-art climate models

    Science.gov (United States)

    Yokohata, Tokuta; Emori, Seita; Nozawa, Toru; Ogura, Tomoo; Kawamiya, Michio; Tsushima, Yoko; Suzuki, Tatsuo; Yukimoto, Seiji; Abe-Ouchi, Ayako; Hasumi, Hiroyasu; Sumi, Akimasa; Kimoto, Masahide

    2008-10-01

    We compared the climate response of doubled CO2 equilibrium experiments (2 × CO2) by atmosphere-slab ocean coupled general circulation models (ASGCMs) and that of 1% per year CO2 increase experiments (1%CO2 by atmosphere-ocean coupled general circulation models (AOGCMs) using eight state-of-the-art climate models. Climate feedback processes in 2 × CO2 are different from those in 1%CO2, and the equilibrium climate sensitivity (T2×) in 2 × CO2 is different from the effective climate sensitivity (T2×,eff) in 1%CO2. The difference between T2× and T2×,eff is from -1.3 to 1.6 K, a large part of which can be explained by the difference in the ice-albedo and cloud feedback. The largest contribution is cloud SW feedback, and the difference in cloud SW feedback for 2 ×CO2 and 1%CO2 could be determined by the distribution of the SAT anomaly which causes differences in the atmospheric thermal structure. An important factor which determines the difference in ice-albedo feedback is the initial sea ice distribution at the Southern Ocean, which is generally overestimated in 2 ×CO2 as compared to 1%CO2 and observation. Through the comparison of climate feedback processes in 2 ×CO2 and 1%CO2, the possible behaviour of the time evolution of T2×,eff is discussed.

  11. Ecohydrological responses of dense canopies to environmental variability: 2. Role of acclimation under elevated CO2

    Science.gov (United States)

    Drewry, D. T.; Kumar, P.; Long, S.; Bernacchi, C.; Liang, X.-Z.; Sivapalan, M.

    2010-12-01

    The ability to accurately predict land-atmosphere exchange of mass, energy, and momentum over the coming century requires the consideration of plant biochemical, ecophysiological, and structural acclimation to modifications of the ambient environment. Amongst the most important environmental changes experienced by terrestrial vegetation over the last century has been the increase in ambient carbon dioxide (CO2) concentrations, with a projected doubling in CO2 from preindustrial levels by the middle of this century. This change in atmospheric composition has been demonstrated to significantly alter a variety of leaf and plant properties across a range of species, with the potential to modify land-atmosphere interactions and their associated feedbacks. Free Air Carbon Enrichment (FACE) technology has provided significant insight into the functioning of vegetation in natural conditions under elevated CO2, but remains limited in its ability to quantify the exchange of CO2, water vapor, and energy at the canopy scale. This paper addresses the roles of ecophysiological, biochemical, and structural plant acclimation on canopy-scale exchange of CO2, water vapor, and energy through the application of a multilayer canopy-root-soil model (MLCan) capable of resolving changes induced by elevated CO2 through the canopy and soil systems. Previous validation of MLCan flux estimates were made for soybean and maize in the companion paper using a record of six growing seasons of eddy covariance data from the Bondville Ameriflux site. Observations of leaf-level photosynthesis, stomatal conductance, and surface temperature collected at the SoyFACE experimental facility in central Illinois provide a basis for examining the ability of MLCan to capture vegetation responses to an enriched CO2 environment. Simulations of control (370 [ppm]) and elevated (550 [ppm]) CO2 environments allow for an examination of the vertical variation and canopy-scale responses of vegetation states and fluxes

  12. Soil CO2, N2O and Nox Flux Responses to Biofuel Crop Plantation

    Science.gov (United States)

    Liang, L.; Eberwein, J.; Allsman, L.; Grantz, D. A.; Jenerette, D.

    2014-12-01

    Biofuel crops in high temperature environments, e.g, sorghum in southern California, USA, have a high capacity to assimilate atmospheric CO2. Photosynthates from the canopy may provide extra labile carbon source to feed soil microorganisms and influence trace gas fluxes, including CO2, N2O and NOx. Understanding how soil microorganisms balance the carbon (energy) and nitrogen (nutrients) allocation between growing microbial biomass and respiration is critical for evaluating the GHG emissions and emissions of regional air quality pollutants. We conducted experiments in a high temperature agroecosystem both in fallow and sorghum production fields with an experimental nitrogen gradient (0,50 and 100 kg/ha, marked as control, low and high with triplicate repeat) to investigate the CO2, N2O and NOx flux responses. All gas fluxes were measured simultaneously from three replicate locations for each treatment in the field biweekly. Measurements were performed 2-5 days after irrigation. We found that planting sorghum has significant effects on soil CO2 (p<0.0001), N2O (p<0.0001) and NOx (p=0.04) fluxes, but nitrogen amendments only have marginally significant effects on CO2 flux (p=0.07). Surprisingly, no significant response of N2O (p=0.27) and NOx (p=0.61) were observed in responses to N amendments. Compared to the fallow field, the CO2 flux in sorghum field increased 77%, 134% and 202% in control, low and high N level amendments, respectively. N2O flux from the sorghum field are consistently higher than from fallow field, with 207%, 174% and 1064% increase in control, low and high N level amendments, respectively. For the NOx flux, no significant difference was found between fallow and sorghum field. Although nitrogen amendments did not show significant effects on CO2, N2O and NOx flux, the high N treatment in sorghum field continuously gains the highest flux rates. Our results suggested additional C inputs may be an important factor regulating CO2, N2O and NOx fluxes in

  13. Laboratory calibration of the seismo-acoustic response of CO2 saturated sandstones

    Science.gov (United States)

    Siggins, A. F.; Lwin, M.; Wisman, P.

    2009-04-01

    Geological sequestration can be regarded as one of the promising mitigation strategies against the negative effects of atmospheric carbon dioxide on global climate change. Injection of CO2into depleted natural gas reservoirs in particular, sandstone formations at depth with suitable porosity and seals, seems to be a promising scenario for on-land storage. In fact, a demonstration project is currently underway in the Otway Basin in South Eastern Australia under the auspices of the Australian CO2CRC. One of the most useful geophysical remote sensing tools for monitoring sub surface CO2 injection is seismic imaging. Interpretation of seismic data for the quantitative measurement of the distribution and saturations of CO2 in the subsurface requires a knowledge of the effects of CO2as a pore fluid on the seismo-acoustic response of the reservoir rocks. This report describes some recent experiments that we have conducted to investigate this aspect under controlled laboratory conditions at pressures representative of in-situ reservoir conditions. Prior to the availability of core from the actual Otway injection site, two synthetic sandstones were tested ultrasonically in a computer controlled triaxial testing rig under a range of confining pressures and pore pressures representative of in-situ reservoir pressures. These sandstones comprised; (1) a synthetic material with calcite intergranular cement (CIPS) and (2), a synthetic sandstone with silica intergranular cement. Porosities of the sandstones were respectively, 32%,and 33%. Initial testing was carried on the cores at room temperature-dried condition with confining pressures up to 65MPa in steps of 5 MPa. Cores were then flooded with CO2, initially at 6MPa, 22 degrees C, then with liquid phase CO2at pressures from 7MPa to 17 MPa in steps of 5 MPa. Confining pressures varied from 10 MPa to 65 MPa. A limited number of experiments were also conducted in an additional rig at 50oC with supercritical phase CO2. Ultrasonic

  14. CO2 induced growth response in a diatom dominated phytoplankton community from SW Bay of Bengal coastal water

    Science.gov (United States)

    Biswas, Haimanti; Shaik, Aziz Ur Rahman; Bandyopadhyay, Debasmita; Chowdhury, Neha

    2017-11-01

    The ongoing increase in surface seawater CO2 level could potentially impact phytoplankton primary production in coastal waters; however, CO2 sensitivity studies on tropical coastal phytoplankton assemblages are rare. The present study investigated the interactive impacts of variable CO2 level, light and zinc (Zn) addition on the diatom dominated phytoplankton assemblages from the western coastal Bay of Bengal. Increased CO2 supply enhanced particulate organic matter (POC) production; a concomitant depletion in δ13CPOM values at elevated CO2 suggested increased CO2 diffusive influx inside the cell. Trace amount of Zn added under low CO2 level accelerated growth probably by accelerating Zn-Carbonic Anhydrase activity which helps in converting bicarbonate ion to CO2. Almost identical values of δ13CPOM in the low CO2 treated cells grown with and without Zn indicated a low discrimination between 13C and 12C probably due to bicarbonate uptake. These evidences collectively indicated the existence of the carbon concentration mechanisms (CCMs) at low CO2. A minimum growth rate was observed at low CO2 and light limited condition indicating light dependence of CCMs activity. Upon the increase of light and CO2 level, growth response was maximum. The cells grown in the low CO2 levels showed higher light stress (higher values of both diatoxanthin index and the ratio of photo-protective to light-harvesting pigments) that was alleviated by both increasing CO2 supply and Zn addition (probably by efficient light energy utilization in presence of adequate CO2). This is likely that the diatom dominated phytoplankton communities benefited from the increasing CO2 supply and thus may enhance primary production in response to any further increase in coastal water CO2 levels and can have large biogeochemical consequences in the study area.

  15. Phosphorus supply drives nonlinear responses of cottonwood (Populus deltoides) to increases in CO2 concentration from glacial to future concentrations.

    Science.gov (United States)

    Lewis, James D; Ward, Joy K; Tissue, David T

    2010-07-01

    *Despite the importance of nutrient availability in determining plant responses to climate change, few studies have addressed the interactive effects of phosphorus (P) supply and rising atmospheric CO(2) concentration ([CO(2)]) from glacial to modern and future concentrations on tree seedling growth. *The objective of our study was to examine interactive effects across a range of P supply (six concentrations from 0.004 to 0.5 mM) and [CO(2)] (200 (glacial), 350 (modern) and 700 (future) ppm) on growth, dry mass allocation, and light-saturated photosynthesis (A(sat)) in Populus deltoides (cottonwood) seedlings grown in well-watered conditions. *Increasing [CO(2)] from glacial to modern concentrations increased growth by 25% across P treatments, reflecting reduced [CO(2)] limitations to photosynthesis and increased A(sat). Conversely, the growth response to future [CO(2)] was very sensitive to P supply. Future [CO(2)] increased growth by 80% in the highest P supply but only by 7% in the lowest P supply, reflecting P limitations to A(sat), leaf area and leaf area ratio (LAR), compared with modern [CO(2)]. *Our results suggest that future [CO(2)] will minimally increase cottonwood growth in low-P soils, but in high-P soils may stimulate production to a greater extent than predicted based on responses to past increases in [CO(2)]. Our results indicate that the capacity for [CO(2)] stimulation of cottonwood growth does not decline as [CO(2)] rises from glacial to future concentrations.

  16. Elevated CO2and salinity are responsible for phenolics-enrichment in two differently pigmented lettuces.

    Science.gov (United States)

    Sgherri, Cristina; Pérez-López, Usue; Micaelli, Francesco; Miranda-Apodaca, Jon; Mena-Petite, Amaia; Muñoz-Rueda, Alberto; Quartacci, Mike Frank

    2017-06-01

    Both salt stress and high CO 2 level, besides influencing secondary metabolism, can affect oxidative status of plants mainly acting in an opposite way with salinity provoking oxidative stress and elevated CO 2 alleviating it. The aim of the present work was to study the changes in the composition of phenolic acids and flavonoids as well as in the antioxidant activity in two differently pigmented lettuce cvs (green or red leaf) when submitted to salinity (200 mM NaCl) or elevated CO 2 (700 ppm) or to their combination in order to evaluate how a future global change can affect lettuce quality. Following treatments, the red cv. always maintained higher levels of antioxidant secondary metabolites as well as antioxidant activity, proving to be more responsive to altered environmental conditions than the green one. Overall, these results suggest that the application of moderate salinity or elevated CO 2 , alone or in combination, can induce the production of some phenolics that increase the health benefits of lettuce. In particular, moderate salinity was able to induce the synthesis of the flavonoids quercetin, quercetin-3-O-glucoside, quercetin-3-O-glucuronide and quercitrin. Phenolics-enrichment as well as a higher antioxidant capacity were also observed under high CO 2 with the red lettuce accumulating cyanidin, free chlorogenic acid, conjugated caffeic and ferulic acid as well as quercetin, quercetin-3-O-glucoside, quercetin-3-O-glucuronide, luteolin-7-O-glucoside, rutin, quercitrin and kaempferol. When salinity was present in combination with elevated CO 2 , reduction in yield was prevented and a higher presence of phenolic compounds, in particular luteolin, was observed compared to salinity alone. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  17. Plant growth responses to elevated atmospheric CO2 are increased by phosphorus sufficiency but not by arbuscular mycorrhizas

    DEFF Research Database (Denmark)

    Jakobsen, Iver; Smith, Sally E.; Smith, F. Andrew

    2016-01-01

    Capturing the full growth potential in crops under future elevated CO2 (eCO2) concentrations would be facilitated by improved understanding of eCO2 effects on uptake and use of mineral nutrients. This study investigates interactions of eCO2, soil phosphorus (P), and arbuscular mycorrhizal (AM...... into biomass. Expression of PT genes was influenced by eCO2, but effects were inconsistent across genes and species. The ability of eCO2 to partly mitigate P limitation-induced growth reductions in B. distachyon was associated with enhanced P use efficiency, and requirements for P fertilizers may not increase......) symbiosis in Medicago truncatula and Brachypodium distachyon grown under the same conditions. The focus was on eCO2 effects on vegetative growth, efficiency in acquisition and use of P, and expression of phosphate transporter (PT) genes. Growth responses to eCO2 were positive at P sufficiency, but under low...

  18. Plant responses to increasing CO2 reduce estimates of climate impacts on drought severity.

    Science.gov (United States)

    Swann, Abigail L S; Hoffman, Forrest M; Koven, Charles D; Randerson, James T

    2016-09-06

    Rising atmospheric CO2 will make Earth warmer, and many studies have inferred that this warming will cause droughts to become more widespread and severe. However, rising atmospheric CO2 also modifies stomatal conductance and plant water use, processes that are often are overlooked in impact analysis. We find that plant physiological responses to CO2 reduce predictions of future drought stress, and that this reduction is captured by using plant-centric rather than atmosphere-centric metrics from Earth system models (ESMs). The atmosphere-centric Palmer Drought Severity Index predicts future increases in drought stress for more than 70% of global land area. This area drops to 37% with the use of precipitation minus evapotranspiration (P-E), a measure that represents the water flux available to downstream ecosystems and humans. The two metrics yield consistent estimates of increasing stress in regions where precipitation decreases are more robust (southern North America, northeastern South America, and southern Europe). The metrics produce diverging estimates elsewhere, with P-E predicting decreasing stress across temperate Asia and central Africa. The differing sensitivity of drought metrics to radiative and physiological aspects of increasing CO2 partly explains the divergent estimates of future drought reported in recent studies. Further, use of ESM output in offline models may double-count plant feedbacks on relative humidity and other surface variables, leading to overestimates of future stress. The use of drought metrics that account for the response of plant transpiration to changing CO2, including direct use of P-E and soil moisture from ESMs, is needed to reduce uncertainties in future assessment.

  19. Plant responses to increasing CO2 reduce estimates of climate impacts on drought severity

    Science.gov (United States)

    Swann, Abigail L. S.; Hoffman, Forrest M.; Koven, Charles D.; Randerson, James T.

    2016-09-01

    Rising atmospheric CO2 will make Earth warmer, and many studies have inferred that this warming will cause droughts to become more widespread and severe. However, rising atmospheric CO2 also modifies stomatal conductance and plant water use, processes that are often are overlooked in impact analysis. We find that plant physiological responses to CO2 reduce predictions of future drought stress, and that this reduction is captured by using plant-centric rather than atmosphere-centric metrics from Earth system models (ESMs). The atmosphere-centric Palmer Drought Severity Index predicts future increases in drought stress for more than 70% of global land area. This area drops to 37% with the use of precipitation minus evapotranspiration (P-E), a measure that represents the water flux available to downstream ecosystems and humans. The two metrics yield consistent estimates of increasing stress in regions where precipitation decreases are more robust (southern North America, northeastern South America, and southern Europe). The metrics produce diverging estimates elsewhere, with P-E predicting decreasing stress across temperate Asia and central Africa. The differing sensitivity of drought metrics to radiative and physiological aspects of increasing CO2 partly explains the divergent estimates of future drought reported in recent studies. Further, use of ESM output in offline models may double-count plant feedbacks on relative humidity and other surface variables, leading to overestimates of future stress. The use of drought metrics that account for the response of plant transpiration to changing CO2, including direct use of P-E and soil moisture from ESMs, is needed to reduce uncertainties in future assessment.

  20. [Responses of agricultural crops of free-air CO2 enrichment].

    Science.gov (United States)

    Kimball, B A; Zhu, Jianguo; Cheng, Lei; Kobayashi, K; Bindi, M

    2002-10-01

    Over the past decade, free-air CO2 enrichment (FACE) experiments have been conducted on several agricultural crops: wheat(Triticum aestivum L.), perennial ryegrass (Lolium perenne), and rice(Oryza sativa L.) which are C3 grasses; sorghum (Sorghum bicolor (L.) Möench), a C4 grass; white clover (Trifolium repens), a C3 legume; potato (Solanum tuberosum L.), a C3 forb with tuber storage; and cotton (Gossypium hirsutum L.) and grape (Vitis vinifera L.) which are C3 woody perennials. Using reports from these experiments, the relative responses of these crops was discussed with regard to photosynthesis, stomatal conductance, canopy temperature, water use, water potential, leaf area index, shoot and root biomass accumulation, agricultural yield, radiation use efficiency, specific leaf area, tissue nitrogen concentration, nitrogen yield, carbohydrate concentration, phenology, soil microbiology, soil respiration, trace gas emissions, and soil carbon sequestration. Generally, the magnitude of these responses varied with the functional type of plant and with the soil nitrogen and water status. As expected, the elevated CO2 increased photosynthesis and biomass production and yield substantially in C3 species, but little in C4, and it decreased stomatal conductance and transpiration in both C3 and C4 species and greatly improved water-use efficiency in all the crops. Growth stimulations were as large or larger under water-stress compared to well-watered conditions. Growth stimulations of non-legumes were reduced at low soil nitrogen, whereas elevated CO2 strongly stimulated the growth of the clover legume both at ample and under low N conditions. Roots were generally stimulated more than shoots. Woody perennials had larger growth responses to elevated CO2, while at the same time, their reductions in stomatal conductance were smaller. Tissue nitrogen concentrations went down while carbohydrate and some other carbon-based compounds went up due to elevated CO2, with leaves and

  1. Short-term carbon cycling responses of a mature eucalypt woodland to gradual stepwise enrichment of atmospheric CO2 concentration.

    Science.gov (United States)

    Drake, John E; Macdonald, Catriona A; Tjoelker, Mark G; Crous, Kristine Y; Gimeno, Teresa E; Singh, Brajesh K; Reich, Peter B; Anderson, Ian C; Ellsworth, David S

    2016-01-01

    Projections of future climate are highly sensitive to uncertainties regarding carbon (C) uptake and storage by terrestrial ecosystems. The Eucalyptus Free-Air CO2 Enrichment (EucFACE) experiment was established to study the effects of elevated atmospheric CO2 concentrations (eCO2 ) on a native mature eucalypt woodland with low fertility soils in southeast Australia. In contrast to other FACE experiments, the concentration of CO2 at EucFACE was increased gradually in steps above ambient (+0, 30, 60, 90, 120, and 150 ppm CO2 above ambient of ~400 ppm), with each step lasting approximately 5 weeks. This provided a unique opportunity to study the short-term (weeks to months) response of C cycle flux components to eCO2 across a range of CO2 concentrations in an intact ecosystem. Soil CO2 efflux (i.e., soil respiration or Rsoil ) increased in response to initial enrichment (e.g., +30 and +60 ppm CO2 ) but did not continue to increase as the CO2 enrichment was stepped up to higher concentrations. Light-saturated photosynthesis of canopy leaves (Asat ) also showed similar stimulation by elevated CO2 at +60 ppm as at +150 ppm CO2 . The lack of significant effects of eCO2 on soil moisture, microbial biomass, or activity suggests that the increase in Rsoil likely reflected increased root and rhizosphere respiration rather than increased microbial decomposition of soil organic matter. This rapid increase in Rsoil suggests that under eCO2, additional photosynthate was produced, transported belowground, and respired. The consequences of this increased belowground activity and whether it is sustained through time in mature ecosystems under eCO2 are a priority for future research. © 2015 John Wiley & Sons Ltd.

  2. Emphysema on Thoracic CT and Exercise Ventilatory Inefficiency in Mild-to-Moderate COPD.

    Science.gov (United States)

    Jones, Joshua H; Zelt, Joel T; Hirai, Daniel M; Diniz, Camilla V; Zaza, Aida; O'Donnell, Denis E; Neder, J Alberto

    2017-04-01

    There is growing evidence that emphysema on thoracic computed tomography (CT) is associated with poor exercise tolerance in COPD patients with only mild-to-moderate airflow obstruction. We hypothesized that an excessive ventilatory response to exercise (ventilatory inefficiency) would underlie these abnormalities. In a prospective study, 19 patients (FEV1 = 82 ± 13%, 12 Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage 1) and 26 controls underwent an incremental exercise test. Ventilatory inefficiency was assessed by the ventilation ([Formula: see text]E)/CO2 output ([Formula: see text]CO2) nadir. Pulmonary blood flow (PBF) in a submaximal test was calculated by inert gas rebreathing. Emphysema was quantified as % of attenuation areas below 950 HU. Patients typically presented with centrilobular emphysema (76.8 ± 10.1% of total emphysema) in the upper lobes (upper/total lung ratio = 0.82 ± 0.04). They had lower peak oxygen uptake ([Formula: see text]O2), higher [Formula: see text]E/[Formula: see text]CO2 nadir, and greater dyspnea scores than controls (p exercise (p exercise (r = -0.69) (p exercise ventilatory efficiency in mild-to-moderate COPD. Exercise ventilatory inefficiency links structure (emphysema) and function (DLCO) to a key clinical outcome (poor exercise tolerance) in COPD patients with only modest spirometric abnormalities.

  3. Tropical forest responses to increasing [CO2]: current knowledge and opportunities for future research

    Energy Technology Data Exchange (ETDEWEB)

    Cernusak, Lucas [Australian National University, Canberra, Australia; Winter, Klaus [Smithsonian Tropical Research Institute; Dalling, James [University of Illinois, Urbana-Champaign; Holtum, Joseph [James Cook University; Jaramillo, Carlos [Smithsonian Tropical Research Institute; Korner, Christian [University of Basel; Leakey, Andrew D.B. [University of Illinois; Norby, Richard J [ORNL; Poulter, Benjamin [Laboratoire des Sciences du Climat et de l' Environement, France; Turner, Benjamin [Smithsonian Tropical Research Institute; Wright, S. Joseph [Smithsonian Tropical Research Institute

    2013-01-01

    Elevated atmospheric [CO2] (ca) will undoubtedly affect the metabolism of tropical forests worldwide; however, critical aspects of how tropical forests will respond remain largely unknown. Here we review the current state of knowledge about physiological and ecological responses, with the aim of providing a framework that can help to guide future experimental research. Modelling studies have indicated that elevated ca can potentially stimulate photosynthesis more in the tropics than at higher latitudes, because suppression of photorespiration by elevated ca increases with temperature. However, canopy leaves in tropical forests could also potentially reach a high temperature threshold under elevated ca that will moderate the rise in photosynthesis. Belowground responses, including fine root production, nutrient foraging, and soil organic matter processing, will be especially important to the integrated ecosystem response to elevated CO2. Water-use efficiency will increase as ca rises, potentially impacting upon soil moisture status and nutrient availability. Recruitment may be differentially altered for some functional groups, potentially decreasing ecosystem carbon storage. Whole-forest CO2 enrichment experiments are urgently needed to test predictions of tropical forest functioning under elevated ca. Smaller scale experiments in the understory and in gaps would also be informative, and could provide stepping stones toward stand-scale manipulations.

  4. P ET CO2 e SpO2 permitem ajuste ventilatório adequado em pacientes obesos mórbidos P ET CO2 y SpO2 permiten ajuste de ventilación adecuada en pacientes obesos mórbidos P ET CO2 and SpO2 allow adequate ventilatory adjustment in morbidly obese patients

    Directory of Open Access Journals (Sweden)

    Fábio Ely Martins Benseñor

    2004-08-01

    Full Text Available JUSTIFICATIVA E OBJETIVOS: Apesar das diversas propostas ventilatórias para anestesia em pacientes obesos mórbidos, um consenso não foi estabelecido. Este estudo avaliou o ajuste ventilatório nestes pacientes durante anestesia baseado na oximetria e capnografia. MÉTODO: O consentimento prévio foi obtido da Comissão de Ética e dos pacientes. Excluíram-se tabagistas e portadores de doença cardíaca ou pulmonar. Foram estudados 11 pacientes com índice de massa corpórea (IMC de 59,2 ± 8,3 submetidos à gastroplastia sob anestesia geral (Grupo O. Oito não-obesos (IMC 20,2 ± 3,9 submetidos à gastrectomia formaram o grupo controle (NO. Ajustou-se a ventilação visando dióxido de carbono expiratório final (P ET CO2 menor que 40 mmHg e saturação periférica de oxigênio (SpO2 maior que 95%. Não se utilizou PEEP. Através de monitor respiratório CO2SMO Plus, mediu-se espaços mortos fisiológico, alveolar e de vias aéreas (VD phy, VD alv e VD aw e o volume corrente alveolar (VT alv. Amostras de sangue arterial e venoso central permitiram calcular PaO2/FIO2 e VD phy/VT. Os dados foram comparados e analisados por ANOVA (p JUSTIFICATIVA Y OBJETIVOS: A pesar de las diversas propuestas de ventilación para anestesia en pacientes obesos mórbidos, un consenso no fue establecido. Este estudio evaluó el ajuste de ventilación en estos pacientes durante anestesia fundamentado en la oximetria y capnografia. MÉTODO: El consentimiento previo fue obtenido de la Comisión de Ética y de los pacientes. Fueron excluidos fumantes y portadores de enfermedad cardíaca o pulmonar. Fueron estudiados once pacientes con índice de masa corpórea (IMC de 59,2 ± 8,3 sometidos a gastroplastia bajo anestesia general (Grupo O. Ocho no obesos (IMC 20,2 ± 3,9 sometidos a gastrectomia formaron el grupo control (NO. Se ajustó la ventilación visando el dióxido de carbono expiratorio final (P ET CO2 menor que 40 mmHg y saturación periférica de oxígeno (Sp

  5. A layer stripping approach for monitoring CO2 storage sites using surface magnetotelluric responses

    Science.gov (United States)

    Ogaya, X.; Ledo, J.; Queralt, P.; Jones, A. G.; Marcuello, A.

    2015-12-01

    In this work we present an approach, called "layer stripping", to enhance the sensitivity of surface magnetotelluric responses to subtle subsurface temporal variations in electrical resistivity. The proposed methodology is based on the analytical solution of the one-dimensional magnetotelluric problem, and that both resolution and sensitivity to resistivity changes produced at a given depth increase when the data are acquired closer to the depth where the resistivity changes are taking place. Thus, given a well-known geoelectrical baseline model of a reservoir site, the layer stripping approach aims to remove the effects of the upper, unchanging, structures in order to obtain the time-varying magnetotelluric responses at the target depth. The layer stripping methodology is suggested for monitoring all types of reservoirs but in this work we focus on its application on CO2 geological storage sites. Different injections of CO2 are studied simulating one-dimensional and three-dimensional resistivity variations in the reservoir layer, and the feasibility of the method is appraised evaluating the error of the approach. The geoelectrical baseline model of the Hontomín site (Spain) for CO2 geological storage in a deep saline aquifer is used to assess how this methodology could be implemented in an actual monitoring survey. The resistivity model of the site defines the subsurface in the pre-injection state and allows applying the layer stripping approach to remove the effect of the upper structures not affected by injection of the CO2 gas from the surface MT responses. The proposed approach constitutes an innovative contribution to detect resistivity variations and locate them more precisely in the space. The obtained results show the potential of the method also to sense any possible leakage.

  6. Functional response of a near-surface soil microbial community to a simulated underground CO2 storage leak.

    Directory of Open Access Journals (Sweden)

    Sergio E Morales

    Full Text Available Understanding the impacts of leaks from geologic carbon sequestration, also known as carbon capture and storage, is key to developing effective strategies for carbon dioxide (CO2 emissions management and mitigation of potential negative effects. Here, we provide the first report on the potential effects of leaks from carbon capture and storage sites on microbial functional groups in surface and near-surface soils. Using a simulated subsurface CO2 storage leak scenario, we demonstrate how CO2 flow upward through the soil column altered both the abundance (DNA and activity (mRNA of microbial functional groups mediating carbon and nitrogen transformations. These microbial responses were found to be seasonally dependent and correlated to shifts in atmospheric conditions. While both DNA and mRNA levels were affected by elevated CO2, they did not react equally, suggesting two separate mechanisms for soil microbial community response to high CO2 levels. The results did not always agree with previous studies on elevated atmospheric (rather than subsurface CO2 using FACE (Free-Air CO2 Enrichment systems, suggesting that microbial community response to CO2 seepage from the subsurface might differ from its response to atmospheric CO2 increases.

  7. Photoprotective responses in a brown macroalgae Cystoseira tamariscifolia to increases in CO2 and temperature.

    Science.gov (United States)

    Celis-Plá, Paula S M; Martínez, Brezo; Korbee, Nathalie; Hall-Spencer, Jason M; Figueroa, Félix L

    2017-09-01

    Global warming and ocean acidification are increasingly affecting coastal ecosystems, with impacts that vary regionally depending upon local biogeography. Ocean acidification drives shifts in seaweed community dominance that depend on interactions with other factors such as light and nutrients. In this study, we investigated the photophysiological responses in the brown macroalgae species Cystoseira tamariscifolia (Hudson) Papenfuss with important structural role in the coastal Mediterranean communities. These algae were collected in the Cabo de Gata-Nijar Natural Park in ultraoligotrophic waters (algae exposed under high irradiance and less nutrient conditions) vs. those collected in the La Araña beach in oligotrophic waters (algae exposed at middle nutrient and irradiance conditions) in the Mediterranean Sea. They were incubated in mesocosms, under two levels of CO2; ambient (400-500 ppm) and high CO2 (1200-1300 ppm), combined with two temperatures (ambient temperature; 20 °C and ambient temperature + 4 °C; 24 °C) and the same nutrient conditions of the waters of the origin of macroalgae. Thalli from two sites on the Spanish Mediterranean coast were significantly affected by increases in pCO2 and temperature. The carotenoids (fucoxanthin, violaxanthin and β-carotene) contents were higher in algae from oligotrophic than that from ultraoligotrophic water, i.e., algae collected under higher nutrient conditions respect to less conditions, increase photoprotective pigments content. Thalli from both locations upregulated photosynthesis (as Fv/Fm) at increased pCO2 levels. Our study shows that ongoing ocean acidification and warming can increase photoprotection and photosynthesis in intertidal macroalgae. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Plasticity of central chemoreceptors: effect of bilateral carotid body resection on central CO2 sensitivity.

    Directory of Open Access Journals (Sweden)

    Albert Dahan

    2007-07-01

    Full Text Available Human breathing is regulated by feedback and feed-forward control mechanisms, allowing a strict matching between metabolic needs and the uptake of oxygen in the lungs. The most important control mechanism, the metabolic ventilatory control system, is fine-tuned by two sets of chemoreceptors, the peripheral chemoreceptors in the carotid bodies (located in the bifurcation of the common carotid arteries and the central CO2 chemoreceptors in the ventral medulla. Animal data indicate that resection of the carotid bodies results, apart from the loss of the peripheral chemoreceptors, in reduced activity of the central CO2 sensors. We assessed the acute and chronic effect of carotid body resection in three humans who underwent bilateral carotid body resection (bCBR after developing carotid body tumors.The three patients (two men, one woman were suffering from a hereditary form of carotid body tumors. They were studied prior to surgery and at regular intervals for 2-4 y following bCBR. We obtained inspired minute ventilation (Vi responses to hypoxia and CO2. The Vi-CO2 responses were separated into a peripheral (fast response and a central (slow response with a two-compartment model of the ventilatory control system. Following surgery the ventilatory CO2 sensitivity of the peripheral chemoreceptors and the hypoxic responses were not different from zero or below 10% of preoperative values. The ventilatory CO2 sensitivity of the central chemoreceptors decreased by about 75% after surgery, with peak reduction occurring between 3 and 6 mo postoperatively. This was followed by a slow return to values close to preoperative values within 2 y. During this slow return, the Vi-CO2 response shifted slowly to the right by about 8 mm Hg.The reduction in central Vi-CO2 sensitivity after the loss of the carotid bodies suggests that the carotid bodies exert a tonic drive or tonic facilitation on the output of the central chemoreceptors that is lost upon their resection

  9. Plasticity of central chemoreceptors: effect of bilateral carotid body resection on central CO2 sensitivity.

    Science.gov (United States)

    Dahan, Albert; Nieuwenhuijs, Diederik; Teppema, Luc

    2007-07-24

    Human breathing is regulated by feedback and feed-forward control mechanisms, allowing a strict matching between metabolic needs and the uptake of oxygen in the lungs. The most important control mechanism, the metabolic ventilatory control system, is fine-tuned by two sets of chemoreceptors, the peripheral chemoreceptors in the carotid bodies (located in the bifurcation of the common carotid arteries) and the central CO2 chemoreceptors in the ventral medulla. Animal data indicate that resection of the carotid bodies results, apart from the loss of the peripheral chemoreceptors, in reduced activity of the central CO2 sensors. We assessed the acute and chronic effect of carotid body resection in three humans who underwent bilateral carotid body resection (bCBR) after developing carotid body tumors. The three patients (two men, one woman) were suffering from a hereditary form of carotid body tumors. They were studied prior to surgery and at regular intervals for 2-4 y following bCBR. We obtained inspired minute ventilation (Vi) responses to hypoxia and CO2. The Vi-CO2 responses were separated into a peripheral (fast) response and a central (slow) response with a two-compartment model of the ventilatory control system. Following surgery the ventilatory CO2 sensitivity of the peripheral chemoreceptors and the hypoxic responses were not different from zero or below 10% of preoperative values. The ventilatory CO2 sensitivity of the central chemoreceptors decreased by about 75% after surgery, with peak reduction occurring between 3 and 6 mo postoperatively. This was followed by a slow return to values close to preoperative values within 2 y. During this slow return, the Vi-CO2 response shifted slowly to the right by about 8 mm Hg. The reduction in central Vi-CO2 sensitivity after the loss of the carotid bodies suggests that the carotid bodies exert a tonic drive or tonic facilitation on the output of the central chemoreceptors that is lost upon their resection. The

  10. The nonlinear North Atlantic-Arctic ocean response to CO2 forcing

    Science.gov (United States)

    van der Linden, Eveline C.; Bintanja, Richard; Hazeleger, Wilco

    2017-04-01

    Most climate models project an increase in oceanic energy transport towards high northern latitudes in future climate projections, but the physical mechanisms are not yet fully understood. To obtain a more fundamental understanding of the processes that cause the ocean heat transport to increase, we carried out a set of sensitivity experiments using a coupled atmosphere-ocean general circulation model. Within these experiments, atmospheric CO2 levels are instantaneously set to one-fourth to four times current values. These model integrations, each with a length of 550 years, result in five considerably different quasi-equilibrium climate states. Our simulations show that poleward ocean heat transport in the Atlantic sector of the Arctic at 70°N increases from 0.03 PW in the coldest climate state to 0.2 PW in the warmest climate state. This increase is caused primarily by changes in sea ice cover, in horizontal ocean currents owing to anomalous winds in response to sea ice changes, and in ocean advection of thermal anomalies. Surprisingly, at subpolar latitudes, the subpolar gyre is found to weaken toward both the warmer and colder climates, relative to the current climate. This nonlinear response is caused by a complex interplay between seasonal sea ice melt, the near-surface wind response to sea ice changes, and changes in the density-driven circulation. The Atlantic Meridional Overturning Circulation (AMOC) and its associated heat transport even oppose the total ocean heat transport towards the Arctic in the warmest climate. Going from warm to cold climates, or from high to low CO2 concentrations, the strength of the AMOC initially increases, but then declines towards the coldest climate, implying a nonlinear AMOC-response to CO2-induced climate change. Evidently, the North Atlantic-Arctic ocean heat transport depends on an interplay between various (remote) coupled ocean-atmosphere-sea ice mechanisms that respond in a nonlinear way to climate change.

  11. Response of marine bacterioplankton pH homeostasis gene expression to elevated CO2

    Science.gov (United States)

    Bunse, Carina; Lundin, Daniel; Karlsson, Christofer M. G.; Akram, Neelam; Vila-Costa, Maria; Palovaara, Joakim; Svensson, Lovisa; Holmfeldt, Karin; González, José M.; Calvo, Eva; Pelejero, Carles; Marrasé, Cèlia; Dopson, Mark; Gasol, Josep M.; Pinhassi, Jarone

    2016-05-01

    Human-induced ocean acidification impacts marine life. Marine bacteria are major drivers of biogeochemical nutrient cycles and energy fluxes; hence, understanding their performance under projected climate change scenarios is crucial for assessing ecosystem functioning. Whereas genetic and physiological responses of phytoplankton to ocean acidification are being disentangled, corresponding functional responses of bacterioplankton to pH reduction from elevated CO2 are essentially unknown. Here we show, from metatranscriptome analyses of a phytoplankton bloom mesocosm experiment, that marine bacteria responded to lowered pH by enhancing the expression of genes encoding proton pumps, such as respiration complexes, proteorhodopsin and membrane transporters. Moreover, taxonomic transcript analysis showed that distinct bacterial groups expressed different pH homeostasis genes in response to elevated CO2. These responses were substantial for numerous pH homeostasis genes under low-chlorophyll conditions (chlorophyll a 20 μg l-1) were low. Given that proton expulsion through pH homeostasis mechanisms is energetically costly, these findings suggest that bacterioplankton adaptation to ocean acidification could have long-term effects on the economy of ocean ecosystems.

  12. Atmospheric CO2 Alters Resistance of Arabidopsis to Pseudomonas syringae by Affecting Abscisic Acid Accumulation and Stomatal Responsiveness to Coronatine.

    Science.gov (United States)

    Zhou, Yeling; Vroegop-Vos, Irene; Schuurink, Robert C; Pieterse, Corné M J; Van Wees, Saskia C M

    2017-01-01

    Atmospheric CO2 influences plant growth and stomatal aperture. Effects of high or low CO2 levels on plant disease resistance are less well understood. Here, resistance of Arabidopsis thaliana against the foliar pathogen Pseudomonas syringae pv. tomato DC3000 (Pst) was investigated at three different CO2 levels: high (800 ppm), ambient (450 ppm), and low (150 ppm). Under all conditions tested, infection by Pst resulted in stomatal closure within 1 h after inoculation. However, subsequent stomatal reopening at 4 h, triggered by the virulence factor coronatine (COR), occurred only at ambient and high CO2, but not at low CO2. Moreover, infection by Pst was reduced at low CO2 to the same extent as infection by mutant Pst cor(-) . Under all CO2 conditions, the ABA mutants aba2-1 and abi1-1 were as resistant to Pst as wild-type plants under low CO2, which contained less ABA. Moreover, stomatal reopening mediated by COR was dependent on ABA. Our results suggest that reduced ABA levels at low CO2 contribute to the observed enhanced resistance to Pst by deregulation of virulence responses. This implies that enhanced ABA levels at increasing CO2 levels may have a role in weakening plant defense.

  13. Atmospheric CO2 Alters Resistance of Arabidopsis to Pseudomonas syringae by Affecting Abscisic Acid Accumulation and Stomatal Responsiveness to Coronatine

    Directory of Open Access Journals (Sweden)

    Yeling Zhou

    2017-05-01

    Full Text Available Atmospheric CO2 influences plant growth and stomatal aperture. Effects of high or low CO2 levels on plant disease resistance are less well understood. Here, resistance of Arabidopsis thaliana against the foliar pathogen Pseudomonas syringae pv. tomato DC3000 (Pst was investigated at three different CO2 levels: high (800 ppm, ambient (450 ppm, and low (150 ppm. Under all conditions tested, infection by Pst resulted in stomatal closure within 1 h after inoculation. However, subsequent stomatal reopening at 4 h, triggered by the virulence factor coronatine (COR, occurred only at ambient and high CO2, but not at low CO2. Moreover, infection by Pst was reduced at low CO2 to the same extent as infection by mutant Pst cor-. Under all CO2 conditions, the ABA mutants aba2-1 and abi1-1 were as resistant to Pst as wild-type plants under low CO2, which contained less ABA. Moreover, stomatal reopening mediated by COR was dependent on ABA. Our results suggest that reduced ABA levels at low CO2 contribute to the observed enhanced resistance to Pst by deregulation of virulence responses. This implies that enhanced ABA levels at increasing CO2 levels may have a role in weakening plant defense.

  14. Response of the Atlantic Thermohaline Circulation to Increased Atmospheric CO2 in a Coupled Model.

    Science.gov (United States)

    Hu, Aixue; Meehl, Gerald A.; Washington, Warren M.; Dai, Aiguo

    2004-11-01

    Changes in the thermohaline circulation (THC) due to increased CO2 are important in future climate regimes. Using a coupled climate model, the Parallel Climate Model (PCM), regional responses of the THC in the North Atlantic to increased CO2 and the underlying physical processes are studied here. The Atlantic THC shows a 20-yr cycle in the control run, qualitatively agreeing with other modeling results. Compared with the control run, the simulated maximum of the Atlantic THC weakens by about 5 Sv (1 Sv 106 m3 s-1) or 14% in an ensemble of transient experiments with a 1% CO2 increase per year at the time of CO2 doubling. The weakening of the THC is accompanied by reduced poleward heat transport in the midlatitude North Atlantic. Analyses show that oceanic deep convective activity strengthens significantly in the Greenland Iceland Norway (GIN) Seas owing to a saltier (denser) upper ocean, but weakens in the Labrador Sea due to a fresher (lighter) upper ocean and in the south of the Denmark Strait region (SDSR) because of surface warming. The saltiness of the GIN Seas are mainly caused by an increased salty North Atlantic inflow, and reduced sea ice volume fluxes from the Arctic into this region. The warmer SDSR is induced by a reduced heat loss to the atmosphere, and a reduced sea ice flux into this region, resulting in less heat being used to melt ice. Thus, sea ice related salinity effects appear to be more important in the GIN Seas, but sea ice melt-related thermal effects seem to be more important in the SDSR region. On the other hand, the fresher Labrador Sea is mainly attributed to increased precipitation. These regional changes produce the overall weakening of the THC in the Labrador Sea and SDSR, and more vigorous ocean overturning in the GIN Seas. The northward heat transport south of 60°N is reduced with increased CO2, but increased north of 60°N due to the increased flow of North Atlantic water across this latitude.

  15. Multi-Year Leaf-Level Response to Sub-Ambient and Elevated Experimental CO2 in Betula nana

    NARCIS (Netherlands)

    Hincke, Alexandra J C; Broere, Tom; Kürschner, Wolfram M; Donders, Timme H; Wagner-Cremer, Friederike

    2016-01-01

    The strong link between stomatal frequency and CO2 in woody plants is key for understanding past CO2 dynamics, predicting future change, and evaluating the significant role of vegetation in the hydrological cycle. Experimental validation is required to evaluate the long-term adaptive leaf response

  16. [Likeness between respiratory responses on CO2 in conditions of natural breathing and voluntary-controlled mechanical ventilation].

    Science.gov (United States)

    Pogodin, M A; Granstrem, M P; Dimitrienko, A I

    2007-04-01

    We did Read CO2 rebreathing tests in 8 adult males. Both at natural breathing, and at self-controlled mechanical ventilation, volunteers increased ventilation proportionally to growth end-tidal PCO2. Inside individual distinctions of responses to CO2 during controlled mechanical ventilation are result of the voluntary motor control.

  17. Carbon residence time dominates uncertainty in terrestrial vegetation responses to future climate and atmospheric CO2.

    Science.gov (United States)

    Friend, Andrew D; Lucht, Wolfgang; Rademacher, Tim T; Keribin, Rozenn; Betts, Richard; Cadule, Patricia; Ciais, Philippe; Clark, Douglas B; Dankers, Rutger; Falloon, Pete D; Ito, Akihiko; Kahana, Ron; Kleidon, Axel; Lomas, Mark R; Nishina, Kazuya; Ostberg, Sebastian; Pavlick, Ryan; Peylin, Philippe; Schaphoff, Sibyll; Vuichard, Nicolas; Warszawski, Lila; Wiltshire, Andy; Woodward, F Ian

    2014-03-04

    Future climate change and increasing atmospheric CO2 are expected to cause major changes in vegetation structure and function over large fractions of the global land surface. Seven global vegetation models are used to analyze possible responses to future climate simulated by a range of general circulation models run under all four representative concentration pathway scenarios of changing concentrations of greenhouse gases. All 110 simulations predict an increase in global vegetation carbon to 2100, but with substantial variation between vegetation models. For example, at 4 °C of global land surface warming (510-758 ppm of CO2), vegetation carbon increases by 52-477 Pg C (224 Pg C mean), mainly due to CO2 fertilization of photosynthesis. Simulations agree on large regional increases across much of the boreal forest, western Amazonia, central Africa, western China, and southeast Asia, with reductions across southwestern North America, central South America, southern Mediterranean areas, southwestern Africa, and southwestern Australia. Four vegetation models display discontinuities across 4 °C of warming, indicating global thresholds in the balance of positive and negative influences on productivity and biomass. In contrast to previous global vegetation model studies, we emphasize the importance of uncertainties in projected changes in carbon residence times. We find, when all seven models are considered for one representative concentration pathway × general circulation model combination, such uncertainties explain 30% more variation in modeled vegetation carbon change than responses of net primary productivity alone, increasing to 151% for non-HYBRID4 models. A change in research priorities away from production and toward structural dynamics and demographic processes is recommended.

  18. Elevated CO2 Increases Nitrogen Fixation at the Reproductive Phase Contributing to Various Yield Responses of Soybean Cultivars

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    Yansheng Li

    2017-09-01

    Full Text Available Nitrogen deficiency limits crop performance under elevated CO2 (eCO2, depending on the ability of plant N uptake. However, the dynamics and redistribution of N2 fixation, and fertilizer and soil N use in legumes under eCO2 have been little studied. Such an investigation is essential to improve the adaptability of legumes to climate change. We took advantage of genotype-specific responses of soybean to increased CO2 to test which N-uptake phenotypes are most strongly related to enhanced yield. Eight soybean cultivars were grown in open-top chambers with either 390 ppm (aCO2 or 550 ppm CO2 (eCO2. The plants were supplied with 100 mg N kg−1 soil as 15N-labeled calcium nitrate, and harvested at the initial seed-filling (R5 and full-mature (R8 stages. Increased yield in response to eCO2 correlated highly (r = 0.95 with an increase in symbiotically fixed N during the R5 to R8 stage. In contrast, eCO2 only led to small increases in the uptake of fertilizer-derived and soil-derived N during R5 to R8, and these increases did not correlate with enhanced yield. Elevated CO2 also decreased the proportion of seed N redistributed from shoot to seeds, and this decrease strongly correlated with increased yield. Moreover, the total N uptake was associated with increases in fixed-N per nodule in response to eCO2, but not with changes in nodule biomass, nodule density, or root length.

  19. Pressure-Responsive, Surfactant-Free CO2-Based Nanostructured Fluids.

    Science.gov (United States)

    Grimaldi, Natascia; Rojas, Paula Elena; Stehle, Simon; Cordoba, Alba; Schweins, Ralf; Sala, Santi; Luelsdorf, Stefan; Piña, David; Veciana, Jaume; Faraudo, Jordi; Triolo, Alessandro; Braeuer, Andreas Siegfried; Ventosa, Nora

    2017-11-28

    Microemulsions are extensively used in advanced material and chemical processing. However, considerable amounts of surfactant are needed for their formulation, which is a drawback due to both economic and ecological reasons. Here, we describe the nanostructuration of recently discovered surfactant-free, carbon dioxide (CO2)-based microemulsion-like systems in a water/organic-solvent/CO2 pressurized ternary mixture. "Water-rich" nanodomains embedded into a "water-depleted" matrix have been observed and characterized by the combination of Raman spectroscopy, molecular dynamics simulations, and small-angle neutron scattering. These single-phase fluids show a reversible, pressure-responsive nanostructuration; the "water-rich" nanodomains at a given pressure can be instantaneously degraded/expanded by increasing/decreasing the pressure, resulting in a reversible, rapid, and homogeneous mixing/demixing of their content. This pressure-triggered responsiveness, together with other inherent features of these fluids, such as the absence of any contaminant in the ternary mixture (e.g., surfactant), their spontaneous formation, and their solvation capability (enabling the dissolution of both hydrophobic and hydrophilic molecules), make them appealing complex fluid systems to be used in molecular material processing and in chemical engineering.

  20. Multi-scale modeling of Arabidopsis thaliana response to different CO2 conditions: From gene expression to metabolic flux.

    Science.gov (United States)

    Liu, Lin; Shen, Fangzhou; Xin, Changpeng; Wang, Zhuo

    2016-01-01

    Multi-scale investigation from gene transcript level to metabolic activity is important to uncover plant response to environment perturbation. Here we integrated a genome-scale constraint-based metabolic model with transcriptome data to explore Arabidopsis thaliana response to both elevated and low CO2 conditions. The four condition-specific models from low to high CO2 concentrations show differences in active reaction sets, enriched pathways for increased/decreased fluxes, and putative post-transcriptional regulation, which indicates that condition-specific models are necessary to reflect physiological metabolic states. The simulated CO2 fixation flux at different CO2 concentrations is consistent with the measured Assimilation-CO2intercellular curve. Interestingly, we found that reactions in primary metabolism are affected most significantly by CO2 perturbation, whereas secondary metabolic reactions are not influenced a lot. The changes predicted in key pathways are consistent with existing knowledge. Another interesting point is that Arabidopsis is required to make stronger adjustment on metabolism to adapt to the more severe low CO2 stress than elevated CO2 . The challenges of identifying post-transcriptional regulation could also be addressed by the integrative model. In conclusion, this innovative application of multi-scale modeling in plants demonstrates potential to uncover the mechanisms of metabolic response to different conditions. © 2015 Institute of Botany, Chinese Academy of Sciences.

  1. Ocean acidification and responses to predators: can sensory redundancy reduce the apparent impacts of elevated CO2 on fish?

    Science.gov (United States)

    Lönnstedt, Oona M; Munday, Philip L; McCormick, Mark I; Ferrari, Maud C O; Chivers, Douglas P

    2013-01-01

    Carbon dioxide (CO2) levels in the atmosphere and surface ocean are rising at an unprecedented rate due to sustained and accelerating anthropogenic CO2 emissions. Previous studies have documented that exposure to elevated CO2 causes impaired antipredator behavior by coral reef fish in response to chemical cues associated with predation. However, whether ocean acidification will impair visual recognition of common predators is currently unknown. This study examined whether sensory compensation in the presence of multiple sensory cues could reduce the impacts of ocean acidification on antipredator responses. When exposed to seawater enriched with levels of CO2 predicted for the end of this century (880 μatm CO2), prey fish completely lost their response to conspecific alarm cues. While the visual response to a predator was also affected by high CO2, it was not entirely lost. Fish exposed to elevated CO2, spent less time in shelter than current-day controls and did not exhibit antipredator signaling behavior (bobbing) when multiple predator cues were present. They did, however, reduce feeding rate and activity levels to the same level as controls. The results suggest that the response of fish to visual cues may partially compensate for the lack of response to chemical cues. Fish subjected to elevated CO2 levels, and exposed to chemical and visual predation cues simultaneously, responded with the same intensity as controls exposed to visual cues alone. However, these responses were still less than control fish simultaneously exposed to chemical and visual predation cues. Consequently, visual cues improve antipredator behavior of CO2 exposed fish, but do not fully compensate for the loss of response to chemical cues. The reduced ability to correctly respond to a predator will have ramifications for survival in encounters with predators in the field, which could have repercussions for population replenishment in acidified oceans. PMID:24223291

  2. Heart rate response during a simulated Olympic boxing match is predominantly above ventilatory threshold 2: a cross sectional study

    Directory of Open Access Journals (Sweden)

    de Lira CA

    2013-07-01

    Full Text Available Claudio Andre Barbosa de Lira,1 Luiz Fernando Peixinho-Pena,2 Rodrigo Luiz Vancini1,2 Rafael Júlio de Freitas Guina Fachina,3,4 Alexandre Aparecido de Almeida,2 Marília dos Santos Andrade,2 Antonio Carlos da Silva2 1Setor de Fisiologia Humana e do Exercício, Universidade Federal de Goiás (UFG, Câmpus Jataí, Jataí, GO, Brazil; 2Departamento de Fisiologia, Universidade Federal de São Paulo (UNIFESP, São Paulo, SP, Brazil; 3Departamento de Ciência do Esporte, Faculdade de Educação Física (FEF, Universidade Estadual de Campinas (UNICAMP, Campinas, Brazil; 4Confederação Brasileira de Basketball (CBB, Rio de Janeiro, Brazil Abstract: The present study aimed to describe heart rate (HR responses during a simulated Olympic boxing match and examine physiological parameters of boxing athletes. Ten highly trained Olympic boxing athletes (six men and four women performed a maximal graded exercise test on a motorized treadmill to determine maximal oxygen uptake (52.2 mL · kg-1 · min-1 ± 7.2 mL · kg-1 · min-1 and ventilatory thresholds 1 and 2. Ventilatory thresholds 1 and 2 were used to classify the intensity of exercise based on respective HR during a boxing match. In addition, oxygen uptake (VO2 was estimated during the match based on the HR response and the HR-VO2 relationship obtained from a maximal graded exercise test for each participant. On a separate day, participants performed a boxing match lasting three rounds, 2 minutes each, with a 1-minute recovery period between each round, during which HR was measured. In this context, HR and VO2 were above ventilatory threshold 2 during 219.8 seconds ± 67.4 seconds. There was an increase in HR and VO2 as a function of round (round 3 < round 2 < round 1, P < 0.0001.These findings may direct individual training programs for boxing practitioners and other athletes. Keywords: heart rate, physiological profile, intermittent exercise, combat sports, boxing

  3. Photosynthesis of C3 and C4 Species in Response to Increased CO2 Concentration and Drought Stress

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    HAMIM

    2005-12-01

    Full Text Available Photosynthetic gas exchange in response to increased carbon dioxide concentration ([CO2] and drought stress of two C3 (wheat and kale and two C4 species (Echinochloa crusgallii and Amaranthus caudatus were analysed. Plants were grown in controlled growth chambers with ambient (350 μmol mol−1 and doubled ambient [CO2]. Drought was given by withholding water until the plants severely wilted, whereas the control plants were watered daily. Even though stomatal conductance (Gs of C4 species either under ambient or double [CO2] was lower than those in C3, doubled [CO2] decreased Gs of all species under well watered conditions. As a result, the plants grown under doubled [CO2] transpired less water than those grown under ambient [CO2]. Photosynthesis (Pn of the C4 species was sustained during moderate drought when those of the C3 species decreased significantly. Doubled [CO2] increased photosynthesis of C3 but not of C4 species. Increased [CO2] was only able to delay Pn reduction of all species due to the drought, but not remove it completely. The positive effects of increased [CO2] during moderate drought and the disappearance of it under severe drought suggesting that metabolic effect may limit photosynthesis under severe drought.

  4. Photosynthesis of C3 and C4 Species in Response to Increased CO2 Concentration and Drought Stress

    Directory of Open Access Journals (Sweden)

    HAMIM

    2005-12-01

    Full Text Available Photosynthetic gas exchange in response to increased carbon dioxide concentration ([CO2] and drought stress of two C3 (wheat and kale and two C4 species (Echinochloa crusgallii and Amaranthus caudatus were analysed. Plants were grown in controlled growth chambers with ambient (350 mol mol-1 and doubled ambient [CO2]. Drought was given by withholding water until the plants severely wilted, whereas the control plants were watered daily. Even though stomatal conductance (Gs of C4 species either under ambient or double [CO2] was lower than those in C3, doubled [CO2] decreased Gs of all species under well watered conditions. As a result, the plants grown under doubled [CO2] transpired less water than those grown under ambient [CO2]. Photosynthesis (Pn of the C4 species was sustained during moderate drought when those of the C3 species decreased significantly. Doubled [CO2] increased photosynthesis of C3 but not of C4 species. Increased [CO2] was only able to delay Pn reduction of all species due to the drought, but not remove it completely. The positive effects of increased [CO2] during moderate drought and the disappearance of it under severe drought suggesting that metabolic effect may limit photosynthesis under severe drought.

  5. Modelling plant responses to elevated CO2: how important is leaf area index?

    NARCIS (Netherlands)

    Ewert, F.

    2004-01-01

    Background and Aims The problem of increasing CO2 concentration [CO2] and associated climate change has [CO2] on plants. While variation in growth and productivity is generated much interest in modelling effects of closely related to the amount of intercepted radiation, largely determined by leaf

  6. Response of microalgae to elevated CO2 and temperature: impact of climate change on freshwater ecosystems.

    Science.gov (United States)

    Li, Wei; Xu, Xiaoguang; Fujibayashi, Megumu; Niu, Qigui; Tanaka, Nobuyuki; Nishimura, Osamu

    2016-10-01

    To estimate the combined effects of elevated CO2 and temperature on microalgae, three typical and worldwide freshwater species, the green alga Scenedesmus acuminatus, the diatom Cyclotella meneghiniana, and the cyanobacterium Microcystis aeruginosa, as well as mixes of these three species were continuously cultured in controlled environment chambers with CO2 at 390 and 1000 ppm and temperatures of 20, 25, and 30 °C. CO2 and temperature significantly affected the production of microalgae. The cell productivity increased under elevated CO2 and temperature. Although the green alga dominated in the mixed culture within all CO2 and temperature conditions, rising temperature and CO2 intensified the competition of the cyanobacterium with other microalgae. CO2 affected the extracellular polymeric substances (EPS) characteristics of the green alga and the cyanobacterium. Elevated CO2 induced the generation of humic substances in the EPS fractions of the green alga, the cyanobacterium, and the mixed culture. The extracellular carbohydrates of the diatom and the extracellular proteins of the cyanobacterium increased with elevated CO2 and temperature, while the extracellular carbohydrates and proteins of the green alga and the mixes increased under elevated CO2 and temperature. There were synergistic effects of CO2 and temperature on the productivity and the EPS of microalgae. Climate change related CO2 and temperature increases will promote autochthonous organic carbon production in aquatic ecosystems and facilitate the proliferation of cyanobacteria, which potentially changes the carbon cycling and undermines the functioning of ecosystems.

  7. Variation in forest canopy nitrogen and albedo in response to N fertilization and elevated CO2

    Science.gov (United States)

    Wicklein, H. F.; Ollinger, S. V.; Martin, M.; Hollinger, D. Y.; Collatz, G. J.

    2009-12-01

    It is important to understand how high levels of nitrogen (N) deposition, through changes in N status, could influence a forest’s albedo and photosynthetic rates, and therefore the forest’s overall feedback (positive or negative) to global warming. Foliar N and albedo have recently been shown to covary at the canopy level across temperate and boreal forests. The purpose of this study is to examine the nature of this relationship from leaf to canopy scales and how it might change in response N and CO2 fertilization. Research was conducted at two long-term forest experimental sites. The chronic N amendment site at Harvard Forest in Petersham, MA includes three treatments: high N (fertilized with 150 kg N ha-1 yr-1), low N (50 kg N ha-1 yr-1), and ambient deposition (around 8 kg N ha-1 yr-1). The Oak Ridge National Environmental Research Park in Oak Ridge, TN includes a Free Air CO2 Enrichment (FACE) site where plots receive either ambient and elevated CO2 (540 ppm), and an N amendment site where plots are either fertilized with N (200 kg N ha-1 yr-1) or receive ambient deposition (10-15 kg N ha-1 yr-1). At Harvard Forest we measured seven black oak (Quercus velutina) and five red maple (Acer rubrum) trees in each treatment plot. At Oak Ridge we measured five sweetgum (Liquidambar styraciflua) trees in each FACE treatment plot, and four sweetgum trees in each N amendment treatment plot. Leaves were collected from two to three canopy heights from trees in each treatment plot. For each tree height we measured reflectance and transmittance spectra for stacks of 1, 2, 4, and 8 leaves, both abaxial and adaxial sides. We also measured N concentration, water content, and leaf mass per unit area (LMA) of the leaves. Canopy-level reflectance was modeled using the Scattering by Arbitrarily Inclined Leaves (SAIL-2) radiative transfer model. Preliminary results show significant differences in average leaf-level reflectance in the N fertilized treatments, with higher NIR

  8. Sensitivity analysis of modelled responses of vegetation dynamics on the Tibetan Plateau to doubled CO2 and associated climate change

    Science.gov (United States)

    Qiu, Linjing; Liu, Xiaodong

    2016-04-01

    Increases in the atmospheric CO2 concentration affect both the global climate and plant metabolism, particularly for high-altitude ecosystems. Because of the limitations of field experiments, it is difficult to evaluate the responses of vegetation to CO2 increases and separate the effects of CO2 and associated climate change using direct observations at a regional scale. Here, we used the Community Earth System Model (CESM, version 1.0.4) to examine these effects. Initiated from bare ground, we simulated the vegetation composition and productivity under two CO2 concentrations (367 and 734 ppm) and associated climate conditions to separate the comparative contributions of doubled CO2 and CO2-induced climate change to the vegetation dynamics on the Tibetan Plateau (TP). The results revealed whether the individual effect of doubled CO2 and its induced climate change or their combined effects caused a decrease in the foliage projective cover (FPC) of C3 arctic grass on the TP. Both doubled CO2 and climate change had a positive effect on the FPC of the temperate and tropical tree plant functional types (PFTs) on the TP, but doubled CO2 led to FPC decreases of C4 grass and broadleaf deciduous shrubs, whereas the climate change resulted in FPC decrease in C3 non-arctic grass and boreal needleleaf evergreen trees. Although the combination of the doubled CO2 and associated climate change increased the area-averaged leaf area index (LAI), the effect of doubled CO2 on the LAI increase (95 %) was larger than the effect of CO2-induced climate change (5 %). Similarly, the simulated gross primary productivity (GPP) and net primary productivity (NPP) were primarily sensitive to the doubled CO2, compared with the CO2-induced climate change, which alone increased the regional GPP and NPP by 251.22 and 87.79 g C m-2 year-1, respectively. Regionally, the vegetation response was most noticeable in the south-eastern TP. Although both doubled CO2 and associated climate change had a

  9. Variation in foliar nitrogen and albedo in response to nitrogen fertilization and elevated CO2.

    Science.gov (United States)

    Wicklein, Haley F; Ollinger, Scott V; Martin, Mary E; Hollinger, David Y; Lepine, Lucie C; Day, Michelle C; Bartlett, Megan K; Richardson, Andrew D; Norby, Richard J

    2012-08-01

    Foliar nitrogen has been shown to be positively correlated with midsummer canopy albedo and canopy near infrared (NIR) reflectance over a broad range of plant functional types (e.g., forests, grasslands, and agricultural lands). To date, the mechanism(s) driving the nitrogen–albedo relationship have not been established, and it is unknown whether factors affecting nitrogen availability will also influence albedo. To address these questions, we examined variation in foliar nitrogen in relation to leaf spectral properties, leaf mass per unit area, and leaf water content for three deciduous species subjected to either nitrogen (Harvard Forest, MA, and Oak Ridge, TN) or CO(2) fertilization (Oak Ridge, TN). At Oak Ridge, we also obtained canopy reflectance data from the airborne visible/infrared imaging spectrometer (AVIRIS) to examine whether canopy-level spectral responses were consistent with leaf-level results. At the leaf level, results showed no differences in reflectance or transmittance between CO(2) or nitrogen treatments, despite significant changes in foliar nitrogen. Contrary to our expectations, there was a significant, but negative, relationship between foliar nitrogen and leaf albedo, a relationship that held for both full spectrum leaf albedo as well as leaf albedo in the NIR region alone. In contrast, remote sensing data indicated an increase in canopy NIR reflectance with nitrogen fertilization. Collectively, these results suggest that altered nitrogen availability can affect canopy albedo, albeit by mechanisms that involve canopy-level processes rather than changes in leaf-level reflectance.

  10. Response of Spring Diatoms to CO2 Availability in the Western North Pacific as Determined by Next-Generation Sequencing

    Science.gov (United States)

    Endo, Hisashi

    2016-01-01

    Next-generation sequencing (NGS) technologies have enabled us to determine phytoplankton community compositions at high resolution. However, few studies have adopted this approach to assess the responses of natural phytoplankton communities to environmental change. Here, we report the impact of different CO2 levels on spring diatoms in the Oyashio region of the western North Pacific as estimated by NGS of the diatom-specific rbcL gene (DNA), which encodes the large subunit of RubisCO. We also examined the abundance and composition of rbcL transcripts (cDNA) in diatoms to assess their physiological responses to changing CO2 levels. A short-term (3-day) incubation experiment was carried out on-deck using surface Oyashio waters under different pCO2 levels (180, 350, 750, and 1000 μatm) in May 2011. During the incubation, the transcript abundance of the diatom-specific rbcL gene decreased with an increase in seawater pCO2 levels. These results suggest that CO2 fixation capacity of diatoms decreased rapidly under elevated CO2 levels. In the high CO2 treatments (750 and 1000 μatm), diversity of diatom-specific rbcL gene and its transcripts decreased relative to the control treatment (350 μatm), as well as contributions of Chaetocerataceae, Thalassiosiraceae, and Fragilariaceae to the total population, but the contributions of Bacillariaceae increased. In the low CO2 treatment, contributions of Bacillariaceae also increased together with other eukaryotes. These suggest that changes in CO2 levels can alter the community composition of spring diatoms in the Oyashio region. Overall, the NGS technology provided us a deeper understanding of the response of diatoms to changes in CO2 levels in terms of their community composition, diversity, and photosynthetic physiology. PMID:27124280

  11. Multi-Year Leaf-Level Response to Sub-Ambient and Elevated Experimental CO2 in Betula nana.

    Directory of Open Access Journals (Sweden)

    Alexandra J C Hincke

    Full Text Available The strong link between stomatal frequency and CO2 in woody plants is key for understanding past CO2 dynamics, predicting future change, and evaluating the significant role of vegetation in the hydrological cycle. Experimental validation is required to evaluate the long-term adaptive leaf response of C3 plants to CO2 conditions; however, studies to date have only focused on short-term single-season experiments and may not capture (1 the full ontogeny of leaves to experimental CO2 exposure or (2 the true adjustment of structural stomatal properties to CO2, which we postulate is likely to occur over several growing seasons. We conducted controlled growth chamber experiments at 150 ppmv, 450 ppmv and 800 ppmv CO2 with woody C3 shrub Betula nana (dwarf birch over two successive annual growing seasons and evaluated the structural stomatal response to atmospheric CO2 conditions. We find that while some adjustment of leaf morphological and stomatal parameters occurred in the first growing season where plants are exposed to experimental CO2 conditions, amplified adjustment of non-plastic stomatal properties such as stomatal conductance occurred in the second year of experimental CO2 exposure. We postulate that the species response limit to CO2 of B. nana may occur around 400-450 ppmv. Our findings strongly support the necessity for multi-annual experiments in C3 perennials in order to evaluate the effects of environmental conditions and provide a likely explanation of the contradictory results between historical and palaeobotanical records and experimental data.

  12. Response of Spring Diatoms to CO2 Availability in the Western North Pacific as Determined by Next-Generation Sequencing.

    Directory of Open Access Journals (Sweden)

    Hisashi Endo

    Full Text Available Next-generation sequencing (NGS technologies have enabled us to determine phytoplankton community compositions at high resolution. However, few studies have adopted this approach to assess the responses of natural phytoplankton communities to environmental change. Here, we report the impact of different CO2 levels on spring diatoms in the Oyashio region of the western North Pacific as estimated by NGS of the diatom-specific rbcL gene (DNA, which encodes the large subunit of RubisCO. We also examined the abundance and composition of rbcL transcripts (cDNA in diatoms to assess their physiological responses to changing CO2 levels. A short-term (3-day incubation experiment was carried out on-deck using surface Oyashio waters under different pCO2 levels (180, 350, 750, and 1000 μatm in May 2011. During the incubation, the transcript abundance of the diatom-specific rbcL gene decreased with an increase in seawater pCO2 levels. These results suggest that CO2 fixation capacity of diatoms decreased rapidly under elevated CO2 levels. In the high CO2 treatments (750 and 1000 μatm, diversity of diatom-specific rbcL gene and its transcripts decreased relative to the control treatment (350 μatm, as well as contributions of Chaetocerataceae, Thalassiosiraceae, and Fragilariaceae to the total population, but the contributions of Bacillariaceae increased. In the low CO2 treatment, contributions of Bacillariaceae also increased together with other eukaryotes. These suggest that changes in CO2 levels can alter the community composition of spring diatoms in the Oyashio region. Overall, the NGS technology provided us a deeper understanding of the response of diatoms to changes in CO2 levels in terms of their community composition, diversity, and photosynthetic physiology.

  13. Combined Effects of CO2 and Light on the N2-Fixing Cyanobacterium Trichodesmium IMS101: Physiological Responses1[OA

    Science.gov (United States)

    Kranz, Sven A.; Levitan, Orly; Richter, Klaus-Uwe; Prášil, Ondřej; Berman-Frank, Ilana; Rost, Björn

    2010-01-01

    Recent studies on the diazotrophic cyanobacterium Trichodesmium erythraeum (IMS101) showed that increasing CO2 partial pressure (pCO2) enhances N2 fixation and growth. Significant uncertainties remain as to the degree of the sensitivity to pCO2, its modification by other environmental factors, and underlying processes causing these responses. To address these questions, we examined the responses of Trichodesmium IMS101 grown under a matrix of low and high levels of pCO2 (150 and 900 μatm) and irradiance (50 and 200 μmol photons m−2 s−1). Growth rates as well as cellular carbon and nitrogen contents increased with increasing pCO2 and light levels in the cultures. The pCO2-dependent stimulation in organic carbon and nitrogen production was highest under low light. High pCO2 stimulated rates of N2 fixation and prolonged the duration, while high light affected maximum rates only. Gross photosynthesis increased with light but did not change with pCO2. HCO3− was identified as the predominant carbon source taken up in all treatments. Inorganic carbon uptake increased with light, but only gross CO2 uptake was enhanced under high pCO2. A comparison between carbon fluxes in vivo and those derived from 13C fractionation indicates high internal carbon cycling, especially in the low-pCO2 treatment under high light. Light-dependent oxygen uptake was only detected under low pCO2 combined with high light or when low-light-acclimated cells were exposed to high light, indicating that the Mehler reaction functions also as a photoprotective mechanism in Trichodesmium. Our data confirm the pronounced pCO2 effect on N2 fixation and growth in Trichodesmium and further show a strong modulation of these effects by light intensity. We attribute these responses to changes in the allocation of photosynthetic energy between carbon acquisition and the assimilation of carbon and nitrogen under elevated pCO2. These findings are supported by a complementary study looking at photosynthetic

  14. Transcriptome response to elevated atmospheric CO2 concentration in the Formosan subterranean termite, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae).

    Science.gov (United States)

    Wu, Wenjing; Li, Zhiqiang; Zhang, Shijun; Ke, Yunling; Hou, Yahui

    2016-01-01

    Carbon dioxide (CO2) is a pervasive chemical stimulus that plays a critical role in insect life, eliciting behavioral and physiological responses across different species. High CO2 concentration is a major feature of termite nests, which may be used as a cue for locating their nests. Termites also survive under an elevated CO2 concentration. However, the mechanism by which elevated CO2 concentration influences gene expression in termites is poorly understood. To gain a better understanding of the molecular basis involved in the adaptation to CO2 concentration, a transcriptome of Coptotermes formosanus Shiraki was constructed to assemble the reference genes, followed by comparative transcriptomic analyses across different CO2 concentration (0.04%, 0.4%, 4% and 40%) treatments. (1) Based on a high throughput sequencing platform, we obtained approximately 20 GB of clean data and revealed 189,421 unigenes, with a mean length and an N50 length of 629 bp and 974 bp, respectively. (2) The transcriptomic response of C. formosanus to elevated CO2 levels presented discontinuous changes. Comparative analysis of the transcriptomes revealed 2,936 genes regulated among 0.04%, 0.4%, 4% and 40% CO2 concentration treatments, 909 genes derived from termites and 2,027 from gut symbionts. Genes derived from termites appears selectively activated under 4% CO2 level. In 40% CO2 level, most of the down-regulated genes were derived from symbionts. (3) Through similarity searches to data from other species, a number of protein sequences putatively involved in chemosensory reception were identified and characterized in C. formosanus, including odorant receptors, gustatory receptors, ionotropic receptors, odorant binding proteins, and chemosensory proteins. We found that most genes associated with carbohydrate metabolism, energy metabolism, and genetic information processing were regulated under different CO2 concentrations. Results suggested that termites adapt to ∼4% CO2 level and their

  15. Scrub-Oak Biomass Stimulation by CO2 Enrichment: Sustained 11 Years But Mediated by Precipitation and Contrasting Species Responses

    Science.gov (United States)

    Seiler, T.; Li, J.; Dijkstra, P.; Anderson, H.; Johnson, D.; Hinkle, R.; Drake, B.

    2007-12-01

    Terrestrial ecosystems may mitigate rising atmospheric carbon dioxide concentration (CO2) through increased carbon uptake and sequestration in plant biomass. Elevated CO2 commonly produces initial stimulation of photosynthesis and growth, but due primarily to complex interactions with climate related factors (i.e. water, light and nutrients), uncertainty regarding long-term biomass response persists. After 11 years of CO2 enrichment (ambient and ambient + 350 ppm) using open-top chambers, aboveground biomass stimulation was sustained in a Florida scrub-oak ecosystem, yielding a 67% increase at final harvest in June 2007. The scrub oaks Quercus geminata and Quercus myrtifolia represented 85% of total ecosystem aboveground biomass but displayed contrasting responses to elevated CO2. Q. myrtifolia showed consistent increase in shoot biomass over the course of the study (128% stimulation by elevated CO2) while shoot biomass of Q. geminata was not significantly increased (+6% difference between treatments). Both species displayed long-term mean stimulation of net leaf photosynthesis to elevated CO2 under saturated light conditions: stimulation of photosynthesis in Q. myrtifolia was nearly twice that in Q. geminata (63% and 35%, respectively). Over the course of the study, Q. geminata consistently displayed photosynthetic acclimation via reductions in maximum carboxylation rate (Vcmax) and maximum rate of electron transport (Jmax) while Q. myrtifolia photosynthesis did not acclimate to elevated CO2. Inter-annual variation in Q. myrtifolia annual biomass increment was correlated with rainfall and elevated CO2 stimulation of absolute biomass accumulation was greatest in wet years. This effect was muted at the ecosystem level because CO2 stimulation of biomass in Q. geminata, which utilizes the water table to a greater extent than Q. myrtifolia, showed no relationship with rainfall. These advantages afforded to Q. myrtifolia by elevated CO2 produced a significant change in

  16. Response to elevated CO2 in the temperate C3 grass Festuca arundinaceae across ten soil orders

    Directory of Open Access Journals (Sweden)

    Eric A Nord

    2015-02-01

    Full Text Available Soils vary widely in mineral nutrient availability and physical characteristics, but the influence of this variability on plant responses to elevated CO2 remains poorly understood. As a first approximation of the effect of global soil variability on plant growth response to CO2, we evaluated the effect of CO2 on tall fescue (Festuca arundinacea grown in soils representing 10 of the 12 global soil orders plus a high-fertility control. Plants were grown in small pots in continuously stirred reactor tanks in a greenhouse. Elevated CO2 (800 ppm increased plant biomass in the high-fertility control and in two of the more fertile soils. Elevated CO2 had variable effects on foliar mineral concentration - nitrogen was not altered by elevated CO2, and phosphorus and potassium were only affected by CO2 in a small number of soils. While leaf photosynthesis was stimulated by elevated CO2 in six soils, canopy photosynthesis was not stimulated. Four principle components were identified; the first was associated with foliar minerals and soil clay, and the second with soil acidity and foliar manganese concentration. The third principle component was associated with gas exchange, and the fourth with plant biomass and soil minerals. Soils in which tall fescue did not respond to elevated CO2 account for 83% of global land area. These results show that variation in soil physical and chemical properties have important implications for plant responses to global change, and highlight the need to consider soil variability in models of vegetation response to global change.

  17. Public Responses to CO2 Storage Sites. Lessons from Five European Cases

    Energy Technology Data Exchange (ETDEWEB)

    Oltra, C.; Boso, A. [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas CIEMAT, Madrid (Spain); Upham, P. [Finnish Environment Institute, Helsinki and Centre for Integrated Energy Research, University of Leeds, Leeds (United Kingdom); Riesch, H. [Centre for Environmental Policy, Imperial College London, London (United Kingdom); Brunsting, S. [ECN Policy Studies, Energy Research Centre of the Netherlands ECN, Amsterdam (Netherlands); Duetschke, E. [Fraunhofer-Institut fuer System- und Innovationsforschung ISI, Karlsruhe (Germany); Lis, A. [Department of Sociology and Social Anthropology, Central European University, Budapest (Hungary)

    2012-05-24

    Studies of the factors involved in public perceptions of CO2 storage projects reveal a level of complexity and diversity that arguably confounds a comprehensive theoretical account. To some extent, a conceptual approach that simply organises the relevant social scientific knowledge thematically, rather than seeking an integrated explanation, is as useful as any single account that fails to do justice to the contingencies involved. This paper reviews and assembles such knowledge in terms of six themes and applies these themes to five European cases of carbon capture and storage (CCS) implementation. We identify the main factors involved in community responses to CCS as relating to: the characteristics of the project; the engagement process; risk perceptions; the actions of the stakeholders; the characteristics of the community, and the socio-political context.

  18. A physicochemical framework for interpreting the biological calcification response to CO2-induced ocean acidification

    Science.gov (United States)

    Ries, J. B.

    2011-12-01

    Researchers investigating the responses of marine calcifiers to CO2-induced ocean acidification have reported surprisingly variable results. A generalized proton-pumping-based model of marine organisms' calcifying fluids, considered for present and forecasted atmospheric pCO2 scenarios (400 - 2850 μatm), is able to generate the full spectrum of calcification response patterns observed in prior ocean acidification experiments, including negative, non-linear, and positive. The removal of H+ from an organism's calcifying fluid requires energy. Two factors that influence the amount of energy required to regulate calcification site pH are the quantity of H+ removed from a given volume of the calcifying fluid and the H+-gradient across the membrane(s) that bounds the calcifying fluid. The energy required to maintain a H+-gradient across a membrane, known as the Nernst potential (E), can be defined as: E = (RT)/(nF) x ln([H+]e/[H+]i) where R is the universal gas constant, T is absolute temperature, n is the valence charge of H+, F is the Faraday constant, and [H+]e and [H+]i are H+ concentrations of the external seawater and of the organism's calcifying fluid, respectively. Because R, T, n and F are constants in the described H+-membrane system, the magnitude of the Nernst potential, or the energetic cost of maintaining a H+-gradient between external seawater and an organism's membrane-bound calcifying fluid, should be roughly proportional to [H+]e/[H+]i. The proton-pumping model is therefore parameterized by two end-member scenarios: one in which a fixed number of H+ is removed from the calcifying fluid, regardless of atmospheric pCO2, and another in which a fixed [H+]e/[H+]i is maintained. The model is empirically evaluated for the temperate scleractinian coral Astrangia poculata with in situ pH microelectrode measurements of the coral's calcifying fluid under control and acidified conditions. These measurements reveal that (1) the pH and, thus, aragonite saturation

  19. Responses of soil microbial activity to cadmium pollution and elevated CO2.

    Science.gov (United States)

    Chen, Yi Ping; Liu, Qiang; Liu, Yong Jun; Jia, Feng An; He, Xin Hua

    2014-03-06

    To address the combined effects of cadmium (Cd) and elevated CO2 on soil microbial communities, DGGE (denaturing gradient gel electrophoresis) profiles, respiration, carbon (C) and nitrogen (N) concentrations, loessial soils were exposed to four levels of Cd, i.e., 0 (Cd0), 1.5 (Cd1.5), 3.0 (Cd3.0) and 6.0 (Cd6.0) mg Cd kg(-1) soil, and two levels of CO2, i.e., 360 (aCO2) and 480 (eCO2) ppm. Compared to Cd0, Cd1.5 increased fungal abundance but decreased bacterial abundance under both CO2 levels, whilst Cd3.0 and Cd6.0 decreased both fungal and bacterial abundance. Profiles of DGGE revealed alteration of soil microbial communities under eCO2. Soil respiration decreased with Cd concentrations and was greater under eCO2 than under aCO2. Soil total C and N were greater under higher Cd. These results suggest eCO2 could stimulate, while Cd pollution could restrain microbial reproduction and C decomposition with the restraint effect alleviated by eCO2.

  20. Synergic effect of salinity and CO2 enrichment on growth and photosynthetic responses of the invasive cordgrass Spartina densiflora.

    Science.gov (United States)

    Mateos-Naranjo, Enrique; Redondo-Gómez, Susana; Alvarez, Rosario; Cambrollé, Jesús; Gandullo, Jacinto; Figueroa, M Enrique

    2010-06-01

    Spartina densiflora is a C(4) halophytic species that has proved to have a high invasive potential which derives from its clonal growth and its physiological plasticity to environmental factors, such as salinity. A greenhouse experiment was designed to investigate the synergic effect of 380 and 700 ppm CO(2) at 0, 171, and 510 mM NaCl on the growth and the photosynthetic apparatus of S. densiflora by measuring chlorophyll fluorescence parameters, gas exchange and photosynthetic pigment concentrations. PEPC activity and total ash, sodium, potassium, calcium, magnesium, and zinc concentrations were determined, as well as the C/N ratio. Elevated CO(2) stimulated growth of S. densiflora at 0 and 171 mM NaCl external salinity after 90 d of treatment. This growth enhancement was associated with a greater leaf area and improved leaf water relations rather than with variations in net photosynthetic rate (A). Despite the fact that stomatal conductance decreased in response to 700 ppm CO(2) after 30 d of treatment, A was not affected. This response of A to elevated CO(2) concentration might be explained by an enhanced PEPC carboxylation capacity. On the whole, plant nutrient concentrations declined under elevated CO(2), which can be ascribed to the dilution effect caused by an increase in biomass and the higher water content found at 700 ppm CO(2). Finally, CO(2) and salinity had a marked overall effect on the photochemical (PSII) apparatus and the synthesis of photosynthetic pigments.

  1. The response to high CO2 levels requires the neuropeptide secretion component HID-1 to promote pumping inhibition.

    Directory of Open Access Journals (Sweden)

    Kfir Sharabi

    2014-08-01

    Full Text Available Carbon dioxide (CO2 is a key molecule in many biological processes; however, mechanisms by which organisms sense and respond to high CO2 levels remain largely unknown. Here we report that acute CO2 exposure leads to a rapid cessation in the contraction of the pharynx muscles in Caenorhabditis elegans. To uncover the molecular mechanisms underlying this response, we performed a forward genetic screen and found that hid-1, a key component in neuropeptide signaling, regulates this inhibition in muscle contraction. Surprisingly, we found that this hid-1-mediated pathway is independent of any previously known pathways controlling CO2 avoidance and oxygen sensing. In addition, animals with mutations in unc-31 and egl-21 (neuropeptide secretion and maturation components show impaired inhibition of muscle contraction following acute exposure to high CO2 levels, in further support of our findings. Interestingly, the observed response in the pharynx muscle requires the BAG neurons, which also mediate CO2 avoidance. This novel hid-1-mediated pathway sheds new light on the physiological effects of high CO2 levels on animals at the organism-wide level.

  2. Understanding the drivers of Amazonian evapotranspiration (ET) change in response to increased CO2.

    Science.gov (United States)

    Halladay, Kate; Good, Peter

    2016-04-01

    Earth system models allow us to examine the complex interactions and feedbacks between land surface, vegetation and atmosphere. A more thorough understanding of these interactions is essential in reducing uncertainty surrounding the potential impacts of climate and environmental change on the hydrological cycle and the future state and extent of the Amazon rainforest. With HadGEM2-ES simulations from CMIP5 in which CO2 is increased at 1% per year starting from pre-industrial concentrations and reaching 4 times that after 140 years, we separate the various drivers and processes controlling ET in western Amazonia. The design of these simulations allows for radiative and physiological forcings to be examined separately and in combination, and the degree to which the combination of forcings is additive or non-linear. We consider ET as a product of the moisture gradient between the surface and the boundary layer and a conductance term, which includes terms limiting the evaporation from stomata and from the canopy. We find that aside from the direct effects of radiative and physiological forcing, there are a number of other processes occurring: 1) reductions in ET alter the surface energy budget leading to increases in moisture gradient which drive increases in ET, 2) additional reductions in stomatal conductance when surface temperatures exceed optimum temperature for photosynthesis, leading to greater decreases in ET between 2 and 4 times pre-industrial CO2, 3) negative correlation between moisture gradient and conductance terms leads to additional decreases in ET, 4) decreases in canopy water content increases the importance of stomatal conductance which also drives decreases in ET. A combination of these processes leads to non-linear decreases in ET between 2 and 4 times pre-industrial CO2 when both radiative and physiological forcings are operating. These results indicate a major role physiological forcing in the hydrological cycle of Amazonia, highlight the

  3. Seismic modeling of the AVO/AVA response to CO2 injection at the Ketzin site, Germany

    OpenAIRE

    Ivanova, Alexandra; Bergmann, Peter; Kummerow, Juliane; Yang, Can; Lüth, Stefan; Juhlin, Christopher

    2013-01-01

    Over 64 kilotons of CO2 have been injected (May, 2013) into a heterogeneous sandstone reservoir (saline aquifer) at 630-650 m depth. 4D seismics have been applied to monitor CO2 at the Ketzin site. However, the obtained time-lapse seismic signals have been so far interpreted as being caused by fluid saturation changes only. Modeling of the AVO/AVA response allows us to study two kinds of effects: CO2-saturation- and pore-pressure-related effects. Our results indicate that it is rather infeasi...

  4. Physiological, Behavioral, and Histological Responses of Male C57BL/6N Mice to Different CO2 Chamber Replacement Rates

    Science.gov (United States)

    Boivin, Gregory P; Bottomley, Michael A; Dudley, Emily S; Schiml, Patricia A; Wyatt, Christopher N; Grobe, Nadja

    2016-01-01

    Rodent euthanasia with CO2 by using gradual displacement of 10% to 30% of the chamber volume per minute is considered acceptable by the AVMA Panel on Euthanasia. However, whether a 50% to 100% chamber replacement rate (CRR) of CO2 is more painful or distressful than 10% to 30% CRR is unclear. Therefore, we examined physiological and behavioral parameters, corticosterone and ACTH levels, and lung histology of mice euthanized at CRR of 15%, 30%, 50%, or 100%. Adult male C57BL/6N mice were euthanized at different CO2 CRR as physiological parameters were recorded telemetrically. Video recordings were reviewed to determine when the mouse first became ataxic, when it was fully recumbent (characterized by the mouse's nose resting on the cage floor), and when breathing stopped. Overall, CO2 euthanasia increased cardiovascular parameters and activity. Specific significant differences that were associated with 50% to 100% compared with 15% to 30% CO2 CRR included an increase in systolic blood pressure per second from initiation of CO2 until ataxia, a decrease in total diastolic blood pressure until ataxia, and a decrease in total heart rate until ataxia, immobility, and death. All physiological responses occurred more rapidly with higher CRR. Activity levels, behavioral responses, plasma adrenocorticotropic hormone and corticosterone levels, and lung pathology were not different between groups. We found no physiological, behavioral, or histologic evidence that 15% or 30% CO2 CRR is less painful or distressful than is 50% or 100% CO2 CRR. We conclude that 50% to 100% CO2 CRR is acceptable for euthanizing adult male C57BL/6N mice. PMID:27423153

  5. Phloem function: A key to understanding and manipulating plant responses to rising atmospheric [CO2]?

    Science.gov (United States)

    Increasing atmospheric carbon dioxide concentration ([CO2]) directly stimulates photosynthesis and reduces stomatal conductance in C3 plants. Both of these physiological effects have the potential to alter phloem function at elevated [CO2]. Recent research has clearly established that photosynthetic...

  6. Effect of the transgenerational exposure to elevated CO2 on the drought response of winter wheat

    DEFF Research Database (Denmark)

    Li, Yafei; Li, Xiangnan; Yu, Jingjie

    2017-01-01

    in 4 L pots, and the plants were grown separately in greenhouse cells with either a[CO2] or e[CO2]. At stem elongation stage, in each of the cells half of the plants were subjected to progressive drought stress until all the plant available soil water was depleted, and the other half were well-watered...... effect of e[CO2] in combination of drought on stomatal behavior, plant water consumption and water use efficiency (WUE) have not been investigated. Seeds harvested from plants after two generations (2014–2015) continuously grown in ambient CO2 (a[CO2], 400 μmol L−1) and e[CO2] (800 μmol L−1) were sown...... and served as controls. The results showed that transgenerational exposure of the winter wheat plants to e[CO2] could attenuate the negative impact of drought stress on dry biomass (DM) and WUE. The modulations of multi-generational e[CO2] on leaf abscisic acid concentration, stomatal conductance, and leaf...

  7. The growth response of plants to elevated CO2 under non-optimal environmental conditions

    NARCIS (Netherlands)

    Poorter, H.; Pérez-Soba, M.

    2001-01-01

    Under benign environmental conditions, plant growth is generally stimulated by elevated atmospheric CO2 concentrations. When environmental conditions become sub- or supra-optimal for growth, changes in the biomass enhancement ratio (BER; total plant biomass at elevated CO2 divided by plant biomass

  8. Erythropoietin does not have effects on the ventilatory and pulmonary vascular response to acute hypoxia in men and women.

    Science.gov (United States)

    Berendsen, Remco R; Lindeman, Rob C; Boom, Merel; Aarts, Leon P H J; van Dorp, Eveline L A; Teppema, Luc J

    2016-07-13

    Sustained and chronic hypoxia lead to a rise in pulmonary ventilation (hypoxic ventilatory response, HVR) and to an increase in pulmonary vascular resistance (hypoxic pulmonary vasoconstriction, HPV). In this study, we examined the effect of a clinical intravenous dose of recombinant human erythropoietin (rHuEPO,50 IU kg(-1) ) on the isocapnic HVR and HPV in 7 male and 7 female subjects by exposing them to hypoxia for 20 min (end-tidal PO2  ∼ 50 mmHg) while measuring their ventilation and estimating pulmonary arterial pressure from the maximal velocity of the regurgitant jet over the tricuspid valve during systole (ΔPmax) with echocardiography. In placebo, after 5 and 20 min, men responded with a rise in ventilation by 0.0056 and 0.0023 l/min/kg/%SpO2 , respectively, indicating the presence of hypoxic ventilatory depression. In women, the rise in ventilation was 0.0067 and 0.0047 l/min/kg/%SpO2 , respectively. In both sexes, EPO did not alter these responses significantl . In placebo, mean ΔPmax rose by 6.1 ± 0.7 mmHg in men P = 0.035) and by 8.4 ± 1.4 mmHg in women (P = 0.020) during the hypoxic exposure whereby women had a ∼5 mmHg lower end-tidal PCO2 . EPO did not alter these responses: in men a rise in ΔPmax by 7.5 ± 1.1 mmHg (NS vs. placebo) and in women by 9.7 ± 2.2 mmHg (NS vs. placebo). We conclude that women tended to have a greater HPV in placebo and that a clinical dose of EPO has no effect on the HVR and HPV in either sex This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  9. Interactive Effects of Elevated [CO2] and Drought on the Maize Phytochemical Defense Response against Mycotoxigenic Fusarium verticillioides.

    Directory of Open Access Journals (Sweden)

    Martha M Vaughan

    Full Text Available Changes in climate due to rising atmospheric carbon dioxide concentration ([CO2] are predicted to intensify episodes of drought, but our understanding of how these combined conditions will influence crop-pathogen interactions is limited. We recently demonstrated that elevated [CO2] alone enhances maize susceptibility to the mycotoxigenic pathogen, Fusarium verticillioides (Fv but fumonisin levels remain unaffected. In this study we show that maize simultaneously exposed to elevated [CO2] and drought are even more susceptible to Fv proliferation and also prone to higher levels of fumonisin contamination. Despite the increase in fumonisin levels, the amount of fumonisin produced in relation to pathogen biomass remained lower than corresponding plants grown at ambient [CO2]. Therefore, the increase in fumonisin contamination was likely due to even greater pathogen biomass rather than an increase in host-derived stimulants. Drought did not negate the compromising effects of elevated [CO2] on the accumulation of maize phytohormones and metabolites. However, since elevated [CO2] does not influence the drought-induced accumulation of abscisic acid (ABA or root terpenoid phytoalexins, the effects elevated [CO2] are negated belowground, but the stifled defense response aboveground may be a consequence of resource redirection to the roots.

  10. Genes responsive to elevated CO2 concentrations in triploid white poplar and integrated gene network analysis.

    Directory of Open Access Journals (Sweden)

    Juanjuan Liu

    Full Text Available BACKGROUND: The atmospheric CO2 concentration increases every year. While the effects of elevated CO2 on plant growth, physiology and metabolism have been studied, there is now a pressing need to understand the molecular mechanisms of how plants will respond to future increases in CO2 concentration using genomic techniques. PRINCIPAL FINDINGS: Gene expression in triploid white poplar ((Populus tomentosa ×P. bolleana ×P. tomentosa leaves was investigated using the Affymetrix poplar genome gene chip, after three months of growth in controlled environment chambers under three CO2 concentrations. Our physiological findings showed the growth, assessed as stem diameter, was significantly increased, and the net photosynthetic rate was decreased in elevated CO2 concentrations. The concentrations of four major endogenous hormones appeared to actively promote plant development. Leaf tissues under elevated CO2 concentrations had 5,127 genes with different expression patterns in comparison to leaves under the ambient CO2 concentration. Among these, 8 genes were finally selected for further investigation by using randomized variance model corrective ANOVA analysis, dynamic gene expression profiling, gene network construction, and quantitative real-time PCR validation. Among the 8 genes in the network, aldehyde dehydrogenase and pyruvate kinase were situated in the core and had interconnections with other genes. CONCLUSIONS: Under elevated CO2 concentrations, 8 significantly changed key genes involved in metabolism and responding to stimulus of external environment were identified. These genes play crucial roles in the signal transduction network and show strong correlations with elevated CO2 exposure. This study provides several target genes, further investigation of which could provide an initial step for better understanding the molecular mechanisms of plant acclimation and evolution in future rising CO2 concentrations.

  11. Responses of Mycorrhizal Symbioses to Deliberate Leaks from AN Experimental CO2 Sequestration Field: the Zert Site

    Science.gov (United States)

    Apple, M. E.; Rowe, J. O.; Zhou, X.; Jewell, S.; Dobeck, L.; Cunningham, A.; Spangler, L.

    2012-12-01

    Carbon sequestration is a means of reducing the concentration of atmospheric CO2 . It is important to monitor carbon sequestration fields for surface detection of possible leaks of CO2 . At The Zero Emissions Research Technology (ZERT) site, CO2 is injected at 0.15 tonnes/day increased to 0.3 tonnes/day into the soil through a shallow horizontal injection well with deliberate zones of leaking CO2 , which wells up through the soil and reaches concentrations of 16% w/v. The ZERT site is an experimental facility designed for developing means of surface detection of leaking CO2 and for determining the responses of plants to very high soil CO2 . Within 1 - 2 weeks of CO2 injections, dandelions and grasses begin to form circular zones of leaf dieback called hot spots. While the hotspots are visually apparent, the responses of the underground mycorrhizal symbioses to very high soil CO2 at the ZERT site are as yet undetermined. To examine the effects of leaking CO2 on mycorrhizae, we collected soil and root samples between and at the hotspots before CO2 was injected, then inoculated the rhizosphere with mycorrhizal inoculum containing spores of Glomus and Gigaspora sp., and resampled the soil and roots after three weeks of CO2 injection. We then evaluated the samples for percent mycorrhizal colonization via the line-intercept method in cleared roots in which fungal structures were stained with India-ink. Plants with mycorrhizal fungi benefit by improved P uptake, so we hypothesize that where plants have increased anthocyanin production, a symptom of P deficiency, mycorrhizal colonization would be reduced. In previous summers of the ZERT experiments, leaves have turned red/purple with CO2 exposure, and as of August, 2012, current year leaves appear to have increased anthocyanin above hotspots. Plant roots exude organic carbon into the soil, where it is used by mycorrhizal fungi. Mycorrhizal symbioses are key in the carbon dynamics of soil and in linking the above and below

  12. Examining the Latent Class Structure of CO2 Hypersensitivity using Time Course Trajectories of Panic Response Systems

    Science.gov (United States)

    Roberson-Nay, Roxann; Beadel, Jessica R.; Gorlin, Eugenia I.; Latendresse, Shawn J.; Teachman, Bethany A.

    2014-01-01

    Background and Objectives Carbon dioxide (CO2) hypersensitivity is hypothesized to be a robust endophenotypic marker of panic spectrum vulnerability. The goal of the current study was to explore the latent class trajectories of three primary response systems theoretically associated with CO2 hypersensitivity: subjective anxiety, panic symptoms, and respiratory rate (fR). Methods Participants (n=376; 56% female) underwent a maintained 7.5% CO2 breathing task that included three phases: baseline, CO2 air breathing, and recovery. Growth mixture modeling was used to compare response classes (1..n) to identify the best-fit model for each marker. Panic correlates also were examined to determine class differences in panic vulnerability. Results For subjective anxiety ratings, a three-class model was selected, with individuals in one class reporting an acute increase in anxiety during 7.5% CO2 breathing and a return to pre-CO2 levels during recovery. A second, smaller latent class was distinguished by elevated anxiety across all three phases. The third class reported low anxiety reported during room air, a mild increase in anxiety during 7.5% CO2 breathing, and a return to baseline during recovery. Latent class trajectories for fR yielded one class whereas panic symptom response yielded two classes. Limitations This study examined CO2 hypersensitivity in one of the largest samples to date, but did not ascertain a general population sample thereby limiting generalizability. Moreover, a true resting baseline measure of fR was not measured. Conclusions Two classes potentially representing different risk pathways were observed. Implications of results will be discussed in the context of panic risk research. PMID:25496936

  13. Responses of soil CO2 fluxes to short-term experimental warming in alpine steppe ecosystem, Northern Tibet.

    Directory of Open Access Journals (Sweden)

    Xuyang Lu

    Full Text Available Soil carbon dioxide (CO2 emission is one of the largest fluxes in the global carbon cycle. Therefore small changes in the size of this flux can have a large effect on atmospheric CO2 concentrations and potentially constitute a powerful positive feedback to the climate system. Soil CO2 fluxes in the alpine steppe ecosystem of Northern Tibet and their responses to short-term experimental warming were investigated during the growing season in 2011. The results showed that the total soil CO2 emission fluxes during the entire growing season were 55.82 and 104.31 g C m(-2 for the control and warming plots, respectively. Thus, the soil CO2 emission fluxes increased 86.86% with the air temperature increasing 3.74°C. Moreover, the temperature sensitivity coefficient (Q 10 of the control and warming plots were 2.10 and 1.41, respectively. The soil temperature and soil moisture could partially explain the temporal variations of soil CO2 fluxes. The relationship between the temporal variation of soil CO2 fluxes and the soil temperature can be described by exponential equation. These results suggest that warming significantly promoted soil CO2 emission in the alpine steppe ecosystem of Northern Tibet and indicate that this alpine ecosystem is very vulnerable to climate change. In addition, soil temperature and soil moisture are the key factors that controls soil organic matter decomposition and soil CO2 emission, but temperature sensitivity significantly decreases due to the rise in temperature.

  14. Responses of Soil CO2 Emissions to Extreme Precipitation Regimes: a Simulation on Loess Soil in Semi-arid Regions

    Science.gov (United States)

    Wang, R.; Zhao, M.; Hu, Y.; Guo, S.

    2016-12-01

    Responses of soil CO2 emission to natural precipitation play an essential role in regulating regional C cycling. With more erratic precipitation regimes, mostly likely of more frequent heavy rainstorms, projected into the future, extreme precipitation would potentially affect local soil moisture, plant growth, microbial communities, and further soil CO2 emissions. However, responses of soil CO2 emissions to extreme precipitation have not yet been systematically investigated. Such performances could be of particular importance for rainfed arable soil in semi-arid regions where soil microbial respiration stress is highly sensitive to temporal distribution of natural precipitation.In this study, a simulated experiment was conducted on bare loess soil from the semi-arid Chinese Loess Plateau. Three precipitation regimes with total precipitation amounts of 150 mm, 300 mm and 600 mm were carried out to simulate the extremely dry, business as usual, and extremely wet summer. The three regimes were individually materialized by wetting soils in a series of sub-events (10 mm or 150 mm). Co2 emissions from surface soil were continuously measured in-situ for one month. The results show that: 1) Evident CO2 emission pulses were observed immediately after applying sub-events, and cumulative CO2 emissions from events of total amount of 600 mm were greater than that from 150 mm. 3) In particular, for the same total amount of 600 mm, wetting regimes by applying four times of 150 mm sub-events resulted in 20% less CO2 emissions than by applying 60 times of 10 mm sub-events. This is mostly because its harsh 150 mm storms introduced more over-wet soil microbial respiration stress days (moisture > 28%). As opposed, for the same total amount of 150 mm, CO2 emissions from wetting regimes by applying 15 times of 10 mm sub-events were 22% lower than by wetting at once with 150 mm water, probably because its deficiency of soil moisture resulted in more over-dry soil microbial respiration

  15. Variability of North Sea pH and CO2 in response to North Atlantic Oscillation forcing

    DEFF Research Database (Denmark)

    Salt, Lesley A.; Thomas, Helmuth; Prowe, Friederike

    2013-01-01

    [1] High biological activity causes a distinct seasonality of surface water pH in the North Sea, which is a strong sink for atmospheric CO2 via an effective shelf pump. The intimate connection between the North Sea and the North Atlantic Ocean suggests that the variability of the CO2 system...... of the North Atlantic Ocean may, in part, be responsible for the observed variability of pH and CO2 in the North Sea. In this work, we demonstrate the role of the North Atlantic Oscillation (NAO), the dominant climate mode for the North Atlantic, in governing this variability. Based on three extensive...... observational records covering the relevant levels of the NAO index, we provide evidence that the North Sea pH and CO2 system strongly responds to external and internal expressions of the NAO. Under positive NAO, the higher rates of inflow of water from the North Atlantic Ocean and the Baltic outflow lead...

  16. Model-experiment synthesis at two FACE sites in the southeastern US. Forest ecosystem responses to elevated CO[2]. (Invited)

    Science.gov (United States)

    Walker, A. P.; Zaehle, S.; De Kauwe, M. G.; Medlyn, B. E.; Dietze, M.; Hickler, T.; Iversen, C. M.; Jain, A. K.; Luo, Y.; McCarthy, H. R.; Parton, W. J.; Prentice, C.; Thornton, P. E.; Wang, S.; Wang, Y.; Warlind, D.; Warren, J.; Weng, E.; Hanson, P. J.; Oren, R.; Norby, R. J.

    2013-12-01

    Ecosystem observations from two long-term Free-Air CO[2] Enrichment (FACE) experiments (Duke forest and Oak Ridge forest) were used to evaluate the assumptions of 11 terrestrial ecosystem models and the consequences of those assumptions for the responses of ecosystem water, carbon (C) and nitrogen (N) fluxes to elevated CO[2] (eCO[2]). Nitrogen dynamics were the main constraint on simulated productivity responses to eCO[2]. At Oak Ridge some models reproduced the declining response of C and N fluxes, while at Duke none of the models were able to maintain the observed sustained responses. C and N cycles are coupled through a number of complex interactions, which causes uncertainty in model simulations in multiple ways. Nonetheless, the major difference between models and experiments was a larger than observed increase in N-use efficiency and lower than observed response of N uptake. The results indicate that at Duke there were mechanisms by which trees accessed additional N in response to eCO[2] that were not represented in the ecosystem models, and which did not operate with the same efficiency at Oak Ridge. Sequestration of the additional productivity under eCO[2] into forest biomass depended largely on C allocation. Allocation assumptions were classified into three main categories--fixed partitioning coefficients, functional relationships and a partial (leaf allocation only) optimisation. The assumption which best constrained model results was a functional relationship between leaf area and sapwood area (pipe-model) and increased root allocation when nitrogen or water were limiting. Both, productivity and allocation responses to eCO[2] determined the ecosystem-level response of LAI, which together with the response of stomatal conductance (and hence water-use efficiency; WUE) determined the ecosystem response of transpiration. Differences in the WUE response across models were related to the representation of the relationship of stomatal conductance to CO[2] and

  17. Net photosynthesis in Sphagnum mosses has increased in response to the last century's 100 ppm increase in atmospheric CO2

    Science.gov (United States)

    Serk, Henrik; Nilsson, Mats; Schleucher, Jurgen

    2017-04-01

    Peatlands store >25% of the global soil C pool, corresponding to 1/3 of the contemporary CO2-C in the atmosphere. The majority of the accumulated peat is made up by remains of Sphagnum peat mosses. Thus, understanding how various Sphagnum functional groups respond, and have responded, to increasing atmospheric CO2 and temperature constitutes a major challenge for our understanding of the role of peatlands under a changing climate. We have recently demonstrated (Ehlers et al., 2015, PNAS) that the abundance ratio of two deuterium isotopomers (molecules carrying D at specific intramolecular positions, here D6R/S) of photosynthetic glucose reflects the ratio of oxygenation to carboxylation metabolic fluxes at Rubisco. The photosynthetic glucose is prepared from various plant carbohydrates including cellulose. This finding has been established in CO2 manipulation experiments and observed in carbohydrate derived glucose isolated from herbarium samples of all investigated C-3 species. The isotopomer ratio is connected to specific enzymatic processes thus allowing for mechanistic implicit interpretations. Here we demonstrate a clear increase in net photosynthesis of Sphagnum fuscum in response to the increase of 100 ppm CO2 during the last century as deduced from analysis on S. fuscum remains from peat cores. The D6R/S ratio declines from bottom to top in peat cores, indicating CO2-driven reduction of photorespiration in contemporary moss biomass. In contrast to the hummock-forming S. fuscum, hollow-growing species, e.g. S. majus did not show this response or gave significantly weaker response, suggesting important ecological consequences of rising CO2 on peatland ecosystem services. We hypothesize that photosynthesis in hollow-growing species under water saturation is fully or partly disconnected from the atmospheric CO2 partial pressure and thus showing weaker or no response to increased atmospheric CO2. To further test the field observations we grow both hummock and

  18. The Coupling of Peripheral Blood Pressure and Ventilatory Responses during Exercise in Young Adults with Cystic Fibrosis.

    Directory of Open Access Journals (Sweden)

    Erik H Van Iterson

    Full Text Available Cystic fibrosis (CF is commonly recognized as a pulmonary disease associated with reduced airway function. Another primary symptom of CF is low exercise capacity where ventilation and gas-exchange are exacerbated. However, an independent link between pathophysiology of the pulmonary system and abnormal ventilatory and gas-exchange responses during cardiopulmonary exercise testing (CPET has not been established in CF. Complicating this understanding, accumulating evidence suggests CF demonstrate abnormal peripheral vascular function; although, the clinical implications are unclear. We hypothesized that compared to controls, relative to total work performed (WorkTOT, CF would demonstrate increased ventilation accompanied by augmented systolic blood pressure (SBP during CPET.16 CF and 23 controls (age: 23±4 vs. 27±4 years, P = 0.11; FEV1%predicted: 73±14 vs. 96±5, P<0.01 participated in CPET. Breath-by-breath oxygen uptake ([Formula: see text], ventilation ([Formula: see text], and carbon dioxide output ([Formula: see text] were measured continuously during incremental 3-min stage step-wise cycle ergometry CPET. SBP was measured via manual sphygmomanometry. Linear regression was used to calculate [Formula: see text] slope from rest to peak-exercise.Compared to controls, CF performed less WorkTOT during CPET (90±19 vs. 43±14 kJ, respectively, P<0.01. With WorkTOT as a covariate, peak [Formula: see text] (62±8 vs. 90±4 L/min, P = 0.76, [Formula: see text] (1.8±0.3 vs. 2.7±0.1 L/min, P = 0.40, and SBP (144±13 vs. 152±6 mmHg, P = 0.88 were similar between CF and controls, respectively; whereas CF demonstrated increased [Formula: see text] slope (38±4 vs. 28±2, P = 0.02 but lower peak [Formula: see text] versus controls (22±5 vs. 33±4 mL/kg/min, P<0.01. There were modest-to-moderate correlations between peak SBP with [Formula: see text] (r = 0.30, [Formula: see text] (r = 0.70, and [Formula: see text] (r = 0.62 in CF.These data suggest

  19. Elevated CO2 response of photosynthesis depends on ozone concentration in aspen

    Science.gov (United States)

    Asko Noormets; Olevi Kull; Anu Sober; Mark E. Kubiske; David F. Karnosky

    2010-01-01

    The effect of elevated CO2 and O3 on apparent quantum yield (ø), maximum photosynthesis (Pmax), carboxylation efficiency (Vcmax) and electron transport capacity (Jmax) at different canopy locations was studied in two aspen (Populus...

  20. Soil carbon dioxide (CO2) efflux of two shrubs in response to plant ...

    African Journals Online (AJOL)

    Jane

    2010-10-11

    , Institute of Soil and Water ... Although plant density should affect soil carbon dioxide (CO2) efflux and carbon cycling in semi-arid regions, the effects ...... root and microbial contributions to soil respiration in Leymus chinensis ...

  1. Gene expression responses of paper birch to elevated O3 and CO2 during leaf maturation and senescence

    Science.gov (United States)

    Kontunen-Soppela, S.; Parviainen, J.; Ruhanen, H.; Brosché, M.; Keinanen, M.; Thakur, R. C.; Kolehmainen, M.; Kangasjarvi, J.; Oksanen, E.; Karnosky, D. F.; Vapaavuori, E.

    2009-12-01

    Forest trees are exposed to increasing concentrations of O3 and CO2 simultaneously. The rise of concentration in these gases causes changes in the gene expression of trees, which can be small in acclimated trees, but yet pivotal for the metabolism of the trees. We have studied the response of paper birch (Betula papyrifera) leaf gene expression to elevated O3 and CO2 concentrations during leaf maturation and senescence. The hypotheses were:(1) Elevated O3 induces oxidative stress in leaves. During long O3-exposure repair mechanisms are activated. Because chemical defense requires energy and carbon uptake is reduced, leaf senescence is activated earlier. Alternatively, the senescence-associated processes, remobilization and storage of carbohydrates and nutrients, may not be completed. (2) In the combination of elevated CO2+O3, the O3-caused damages are not seen or they are smaller, due to closure of the stomata under elevated CO2 and decreased O3 uptake by the leaves. On the other hand, elevated CO2 may provide energy and increase defense chemicals, enabling leaves to repair the O3-caused damages. Gene expression responses of paper birch leaves to elevated O3 and CO2 were studied with microarray analyses. Samples were collected from the long-term O3 and CO2 fumigation experiment Aspen FACE in Rhinelander, WI, USA (http://aspenface.mtu.edu/). The site contains 12 FACE rings receiving CO2, O3, CO2+O3, and ambient air (controls). Birches have been exposed to elevated CO2 (550ppm) and O3 (1.5X ambient) since 1998. Leaf samples were collected in July, August and September 2004. The cDNA-microarrays used for hybridizations consisted of Populus euphratica ESTs representing ca 6500 different genes. In order to detect similar gene expression patterns within samplings and treatments, the microarray data was analyzed with multivariate methods; clustering with Self-Organizing Map, finding optimal cluster grouping by K-means clustering and visualizing the results with Sammon

  2. Sensitive indicators of Stipa bungeana response to precipitation under ambient and elevated CO2 concentration

    Science.gov (United States)

    Shi, Yaohui; Zhou, Guangsheng; Jiang, Yanling; Wang, Hui; Xu, Zhenzhu

    2017-09-01

    Precipitation is a primary environmental factor in the semiarid grasslands of northern China. With increased concentrations of atmospheric greenhouse gases, precipitation regimes will change, and high-impact weather events may be more common. Currently, many ecophysiological indicators are known to reflect drought conditions, but these indicators vary greatly among species, and few studies focus on the applicability of these drought indicators under high CO2 conditions. In this study, five precipitation levels (- 30%, - 15%, control, + 15%, and + 30%) were used to simulate the effects of precipitation change on 18 ecophysiological characteristics in Stipa bungeana, including leaf area, plant height, leaf nitrogen (N), and chlorophyll content, among others. Two levels of CO2 concentration (ambient, 390 ppm; 550 ppm) were used to simulate the effects of elevated CO2 on these drought indicators. Using gray relational analysis and phenotypic plasticity analysis, we found that total leaf area or leaf number (morphology), leaf water potential or leaf water content (physiology), and aboveground biomass better reflected the water status of S. bungeana under ambient and elevated CO2 than the 13 other analyzed variables. The sensitivity of drought indicators changed under the elevated CO2 condition. By quantifying the relationship between precipitation and the five most sensitive indicators, we found that the thresholds of precipitation decreased under elevated CO2 concentration. These results will be useful for objective monitoring and assessment of the occurrence and development of drought events in S. bungeana grasslands.

  3. The response of Antarctic sea ice algae to changes in pH and CO2.

    Directory of Open Access Journals (Sweden)

    Andrew McMinn

    Full Text Available Ocean acidification substantially alters ocean carbon chemistry and hence pH but the effects on sea ice formation and the CO2 concentration in the enclosed brine channels are unknown. Microbial communities inhabiting sea ice ecosystems currently contribute 10-50% of the annual primary production of polar seas, supporting overwintering zooplankton species, especially Antarctic krill, and seeding spring phytoplankton blooms. Ocean acidification is occurring in all surface waters but the strongest effects will be experienced in polar ecosystems with significant effects on all trophic levels. Brine algae collected from McMurdo Sound (Antarctica sea ice was incubated in situ under various carbonate chemistry conditions. The carbon chemistry was manipulated with acid, bicarbonate and bases to produce a pCO2 and pH range from 238 to 6066 µatm and 7.19 to 8.66, respectively. Elevated pCO2 positively affected the growth rate of the brine algal community, dominated by the unique ice dinoflagellate, Polarella glacialis. Growth rates were significantly reduced when pH dropped below 7.6. However, when the pH was held constant and the pCO2 increased, growth rates of the brine algae increased by more than 20% and showed no decline at pCO2 values more than five times current ambient levels. We suggest that projected increases in seawater pCO2, associated with OA, will not adversely impact brine algal communities.

  4. Obstructive sleep apnea (OSA) does not affect ventilatory and perceptual responses to exercise in morbidly obese subjects.

    Science.gov (United States)

    Innocenti Bruni, Giulia; Gigliotti, Francesco; Scano, Giorgio

    2012-09-30

    We have tested the hypothesis that high mass loading effects and obstructive sleep apnea (OSA) constrain the ventilatory response to exercise in morbidly obese subjects as compared to their counterparts without OSA. Fifteen obese patients with (8) and without OSA and 12 lean healthy subjects performed incremental cycle exercise. The functional evaluation included ventilation, oxygen uptake, carbon dioxide production, end-expiratory-lung-volumes (EELV), inspiratory capacity, heart rate, dyspnea and leg effort (by a modified Borg scale). Changes in ventilation and dyspnea per unit changes in work rate and metabolic variables were similar in the three groups. Breathing pattern and heart rate increased from rest to peak exercise similarly in the three groups. Leg effort was the prevailing symptom for stopping exercise in most subjects. In conclusion, OSA does not limit exercise capacity in morbidly obese subjects. Ventilation contributes to exertional dyspnea similarly as in lean subjects and in obese patients regardless of OSA. Copyright © 2012 Elsevier B.V. All rights reserved.

  5. Does long-term cultivation of saplings under elevated CO2 concentration influence their photosynthetic response to temperature?

    Science.gov (United States)

    Šigut, Ladislav; Holišová, Petra; Klem, Karel; Šprtová, Mirka; Calfapietra, Carlo; Marek, Michal V.; Špunda, Vladimír; Urban, Otmar

    2015-01-01

    Background and Aims Plants growing under elevated atmospheric CO2 concentrations often have reduced stomatal conductance and subsequently increased leaf temperature. This study therefore tested the hypothesis that under long-term elevated CO2 the temperature optima of photosynthetic processes will shift towards higher temperatures and the thermostability of the photosynthetic apparatus will increase. Methods The hypothesis was tested for saplings of broadleaved Fagus sylvatica and coniferous Picea abies exposed for 4–5 years to either ambient (AC; 385 µmol mol−1) or elevated (EC; 700 µmol mol−1) CO2 concentrations. Temperature response curves of photosynthetic processes were determined by gas-exchange and chlorophyll fluorescence techniques. Key Results Initial assumptions of reduced light-saturated stomatal conductance and increased leaf temperatures for EC plants were confirmed. Temperature response curves revealed stimulation of light-saturated rates of CO2 assimilation (Amax) and a decline in photorespiration (RL) as a result of EC within a wide temperature range. However, these effects were negligible or reduced at low and high temperatures. Higher temperature optima (Topt) of Amax, Rubisco carboxylation rates (VCmax) and RL were found for EC saplings compared with AC saplings. However, the shifts in Topt of Amax were instantaneous, and disappeared when measured at identical CO2 concentrations. Higher values of Topt at elevated CO2 were attributed particularly to reduced photorespiration and prevailing limitation of photosynthesis by ribulose-1,5-bisphosphate (RuBP) regeneration. Temperature response curves of fluorescence parameters suggested a negligible effect of EC on enhancement of thermostability of photosystem II photochemistry. Conclusions Elevated CO2 instantaneously increases temperature optima of Amax due to reduced photorespiration and limitation of photosynthesis by RuBP regeneration. However, this increase disappears when plants

  6. Tree height strongly affects estimates of water-use efficiency responses to climate and CO2 using isotopes.

    Science.gov (United States)

    Brienen, R J W; Gloor, E; Clerici, S; Newton, R; Arppe, L; Boom, A; Bottrell, S; Callaghan, M; Heaton, T; Helama, S; Helle, G; Leng, M J; Mielikäinen, K; Oinonen, M; Timonen, M

    2017-08-18

    Various studies report substantial increases in intrinsic water-use efficiency (W i ), estimated using carbon isotopes in tree rings, suggesting trees are gaining increasingly more carbon per unit water lost due to increases in atmospheric CO2. Usually, reconstructions do not, however, correct for the effect of intrinsic developmental changes in W i as trees grow larger. Here we show, by comparing W i across varying tree sizes at one CO2 level, that ignoring such developmental effects can severely affect inferences of trees' W i . W i doubled or even tripled over a trees' lifespan in three broadleaf species due to changes in tree height and light availability alone, and there are also weak trends for Pine trees. Developmental trends in broadleaf species are as large as the trends previously assigned to CO2 and climate. Credible future tree ring isotope studies require explicit accounting for species-specific developmental effects before CO2 and climate effects are inferred.Intrinsic water-use efficiency (W i ) reconstructions using tree rings often disregard developmental changes in W i as trees age. Here, the authors compare W i across varying tree sizes at a fixed CO2 level and show that ignoring developmental changes impacts conclusions on trees' W i responses to CO2 or climate.

  7. Influence of elevated CO2 and mycorrhizae on nitrogen acquisition: contrasting responses in Pinus taeda and Liquidambar styraciflua.

    Science.gov (United States)

    Constable, J V; Bassirirad, H; Lussenhop, J; Zerihun, A

    2001-02-01

    An understanding of root system capacity to acquire nitrogen (N) is critical in assessing the long-term growth impact of rising atmospheric CO2 concentration ([CO2]) on trees and forest ecosystems. We examined the effects of mycorrhizal inoculation and elevated [CO2] on root ammonium (NH4+) and nitrate (NO3-) uptake capacity in sweetgum (Liquidambar styraciflua L.) and loblolly pine (Pinus taeda L.). Mycorrhizal treatments included inoculation of seedlings with the arbuscular mycorrhizal (AM) fungus Glomus intraradices Schenck & Smith in sweetgum and the ectomycorrhizal (EM) fungus Laccaria bicolor (Maire) Orton in loblolly pine. These plants were then equally divided between ambient and elevated [CO2] treatments. After 6 months of treatment, root systems of both species exhibited a greater uptake capacity for NH4+ than for NO3-. In both species, mycorrhizal inoculation significantly increased uptake capacity for NO3-, but not for NH4+. In sweetgum, the mycorrhizal effect on NO3- and NH4+ uptake capacity depended on growth [C02]. Similarly, in loblolly pine, the mycorrhizal effect on NO3- uptake capacity depended on growth [CO2], but the effect on NH4+ uptake capacity did not. Mycorrhizal inoculation significantly enhanced root nitrate reductase activity (NRA) in both species, but elevated [CO2] increased root NRA only in sweetgum. Leaf NRA in sweetgum did not change significantly with mycorrhizal inoculation, but increased in response to [CO2]. Leaf NRA in loblolly pine was unaffected by either treatment. The results indicate that the mycorrhizal effect on specific root N uptake in these species depends on both the form of inorganic N and the mycorrhizal type. However, our data show that in addressing N status of plants under high [CO2], reliable prediction is possible only when information about other root system adjustments (e.g., biomass allocation to fine roots) is simultaneously considered.

  8. Modelling the electrical resistivity response to CO2 plumes generated in a laboratory, cylindrical sandbox

    Science.gov (United States)

    Kremer, T.; Maineult, A. J.; Binley, A.; Vieira, C.; Zamora, M.

    2012-12-01

    CO2 capture and storage into deep geological formations is one of the main solutions proposed to reduce the concentration of anthropic CO2 in the atmosphere. The monitoring of injection sites is a crucial issue to assess for the long term viability of CO2 storage. With the intention of detecting potential leakages, we are investigating the possibility of using electrical resistivity tomography (ERT) techniques to detect CO2 transfers in the shallow sub-surface. ERT measurements were performed during a CO2 injection in a cylindrical tank filled with Fontainebleau sand and saturated with water. Several measurements protocols were tested. The inversion of the resistances measured with the software R3T (Binley and Kemna (2005)) clearly showed that the CO2 injection induces significant changes in the resistivity distribution of the medium, and that ERT has a promising potential for the detection and survey of CO2 transfers through unconsolidated saturated media. We modeled this experiment using Matlab by building a 3D cellular automaton that describes the CO2 spreading, following the geometric and stochastic approach described by Selker et al. (2007). The CO2 circulation is described as independents, circular and continuous gas channels whose horizontal spread depends on a Gaussian probability law. From the channel distribution we define the corresponding gas concentration distribution and calculate the resistivity of the medium by applying Archie's law for unsaturated conditions. The forward modelling was performed with the software R3T to convert the resistivity distribution into resistances values, each corresponding to one of the electrode arrays used in the experimental measurements. Modelled and measured resistances show a good correlation, except for the electrode arrays located at the top or the bottom of the tank. We improved the precision of the model by considering the effects due to CO2 dissolution in the water which increases the conductivity of the

  9. ventilatory support

    African Journals Online (AJOL)

    Kinfu Betemariam, Gebreyesus Hagos. Abstract. Background: Mechanical Ventilation is a supportive measure for patients who are in respiratory failure. Objective: Designed to identify the commonest pathology responsible for admission to the unit for mechanical respiratory support. Method: A prospective case study ...

  10. Forest fine-root production and nitrogen use under elevated CO2: Contrasting responses explained by a common principle

    Energy Technology Data Exchange (ETDEWEB)

    Franklin, Oscar [International Institute for Applied Systems Analysis; McMurtrie, Ross E [ORNL; Iversen, Colleen M [ORNL; Crous, Kristine [University of Michigan; Finzi, Adrien C [Boston University; Tissue, David Thomas [ORNL; Ellsworth, David [ORNL; Oren, Ram [ORNL; Norby, Richard J [ORNL

    2009-01-01

    Despite the importance of nitrogen (N) limitation of forest carbon (C) sequestration at rising atmospheric CO2 concentration, the mechanisms responsible are not well understood. To elucidate the interactive effects of elevated CO2 (eCO2) and soil N availability on forest productivity and C allocation, we hypothesized that 1) trees maximize fitness by allocating N and C to maximize their net growth, and 2) that N uptake is controlled by root exploration for N. We tested this model using data collected in FACE sites dominated by evergreen (Pinus taeda; Duke Forest) and deciduous (Liquidambar styraciflua; Oak Ridge National Laboratory ORNL) trees. The model explained 80-95% of variation in productivity and N-uptake data among eCO2, N fertilization and control treatments over six years. The model explains why fine-root production increased, and why N uptake increased despite reduced soil N availability under eCO2 at ORNL and Duke. In agreement with observations at other sites, soil N availability reduced below a critical level diminishes all eCO2 responses. At Duke, a negative feedback between reduced soil N availability and N uptake counteracted progressive reduction in soil N availability at eCO2. At ORNL, decreasing soil N availability was perpetuated as it generated no reduction in N uptake, due to strongly increased production of fast turnover fine-roots. This implies that species with fast root turnover could be more prone to progressive N limitation of carbon sequestration in woody biomass than species with slow root turnover, such as evergreens.

  11. Response of salt marsh and mangrove wetlands to changes in atmospheric CO2, climate, and sea-level

    Science.gov (United States)

    Mckee, Karen L.; Rogers, Kerrylee; Saintilan, Neil; Middleton, Beth A.

    2012-01-01

    Coastal salt marsh and mangrove ecosystems are particularly vulnerable to changes in atmospheric CO2 concentrations and associated climate and climate-induced changes. We provide a review of the literature detailing theoretical predictions and observed responses of coastal wetlands to a range of climate change stressors, including CO2, temperature, rainfall, and sea-level rise. This review incorporates a discussion of key processes controlling responses in different settings and thresholds of resilience derived from experimental and observational studies. We specifically consider the potential and observed effects on salt marsh and mangrove vegetation of changes in (1) elevated [CO2] on physiology, growth, and distribution; (2) temperature on distribution and diversity; (3) rainfall and salinity regimes on growth and competitive interactions; and (4) sea level on geomorphological, hydrological, and biological processes.

  12. Peripheral chemoreceptors determine the respiratory sensitivity of central chemoreceptors to CO(2).

    Science.gov (United States)

    Blain, Gregory M; Smith, Curtis A; Henderson, Kathleen S; Dempsey, Jerome A

    2010-07-01

    We assessed the contribution of carotid body chemoreceptors to the ventilatory response to specific CNS hypercapnia in eight unanaesthetized, awake dogs. We denervated one carotid body (CB) and used extracorporeal blood perfusion of the reversibly isolated remaining CB to maintain normal CB blood gases (normoxic, normocapnic perfusate), to inhibit (hyperoxic, hypocapnic perfusate) or to stimulate (hypoxic, normocapnic perfusate) the CB chemoreflex, while the systemic circulation, and therefore the CNS and central chemoreceptors, were exposed consecutively to four progressive levels of systemic arterial hypercapnia via increased fractional inspired CO(2) for 7 min at each level. Neither unilateral CB denervation nor CB perfusion, per se, affected breathing. Relative to CB control conditions (normoxic, normocapnic perfusion), we found that CB chemoreflex inhibition decreased the slope of the ventilatory response to CNS hypercapnia in all dogs to an average of 19% of control values (range 0-38%; n = 6), whereas CB chemoreflex stimulation increased the slope of the ventilatory response to CNS hypercapnia in all dogs to an average of 223% of control values (range 204-235%; n = 4). We conclude that the gain of the CNS CO(2)/H(+) chemoreceptors in dogs is critically dependent on CB afferent activity and that CNS-CB interaction results in hyperadditive ventilatory responses to central hypercapnia.

  13. Peripheral chemoreceptors determine the respiratory sensitivity of central chemoreceptors to CO2

    Science.gov (United States)

    Blain, Gregory M; Smith, Curtis A; Henderson, Kathleen S; Dempsey, Jerome A

    2010-01-01

    We assessed the contribution of carotid body chemoreceptors to the ventilatory response to specific CNS hypercapnia in eight unanaesthetized, awake dogs. We denervated one carotid body (CB) and used extracorporeal blood perfusion of the reversibly isolated remaining CB to maintain normal CB blood gases (normoxic, normocapnic perfusate), to inhibit (hyperoxic, hypocapnic perfusate) or to stimulate (hypoxic, normocapnic perfusate) the CB chemoreflex, while the systemic circulation, and therefore the CNS and central chemoreceptors, were exposed consecutively to four progressive levels of systemic arterial hypercapnia via increased fractional inspired CO2 for 7 min at each level. Neither unilateral CB denervation nor CB perfusion, per se, affected breathing. Relative to CB control conditions (normoxic, normocapnic perfusion), we found that CB chemoreflex inhibition decreased the slope of the ventilatory response to CNS hypercapnia in all dogs to an average of 19% of control values (range 0–38%; n= 6), whereas CB chemoreflex stimulation increased the slope of the ventilatory response to CNS hypercapnia in all dogs to an average of 223% of control values (range 204–235%; n= 4). We conclude that the gain of the CNS CO2/H+ chemoreceptors in dogs is critically dependent on CB afferent activity and that CNS–CB interaction results in hyperadditive ventilatory responses to central hypercapnia. PMID:20421288

  14. CO2 and fire influence tropical ecosystem stability in response to climate change.

    Science.gov (United States)

    Shanahan, Timothy M; Hughen, Konrad A; McKay, Nicholas P; Overpeck, Jonathan T; Scholz, Christopher A; Gosling, William D; Miller, Charlotte S; Peck, John A; King, John W; Heil, Clifford W

    2016-07-18

    Interactions between climate, fire and CO2 are believed to play a crucial role in controlling the distributions of tropical woodlands and savannas, but our understanding of these processes is limited by the paucity of data from undisturbed tropical ecosystems. Here we use a 28,000-year integrated record of vegetation, climate and fire from West Africa to examine the role of these interactions on tropical ecosystem stability. We find that increased aridity between 28-15 kyr B.P. led to the widespread expansion of tropical grasslands, but that frequent fires and low CO2 played a crucial role in stabilizing these ecosystems, even as humidity changed. This resulted in an unstable ecosystem state, which transitioned abruptly from grassland to woodlands as gradual changes in CO2 and fire shifted the balance in favor of woody plants. Since then, high atmospheric CO2 has stabilized tropical forests by promoting woody plant growth, despite increased aridity. Our results indicate that the interactions between climate, CO2 and fire can make tropical ecosystems more resilient to change, but that these systems are dynamically unstable and potentially susceptible to abrupt shifts between woodland and grassland dominated states in the future.

  15. Discussion of Yellow Starthistle Response to Irradiance, Photoperiod, and CO2

    Science.gov (United States)

    Bubenheim, David L.

    2016-01-01

    Yellow Starthistle (Centaurea solstitialis) is a native annual weed of Eurasia and since introduction into the US has become an invasive and noxious weed. It grows in a rosette habit during the vegetative state and usually bolts in summer to produce a large and branched flowering stem. Time to flowering in Yellow Starthistle has been attributed to photoperiod, nitrogen nutrition, temperature, and water stress. We executed a series of studies to investigate the role of light, both photoperiod and photosynthetic photon flux, on flowering and development in Yellow Starthistle. Treatments were presented in 4 ways: (1) Varying day length with constant photosynthetic photon flus (PPF) - providing increasing daily integrated Photosynthetic Photon (PP) exposure with longer day lengths, (2) Varying day length while adjusting PPF to maintain daily PP exposure for all treatments, (3) Extending photoperiod treatments beyond common 12-h photosynthetic period with low light levels to maintain both PPF and daily PP across all treatments; and (4) Reciprocal exchange of plant among photoperiod treatments. Yellow Starthistle appears to be a long-day plant with a critical day length requirement between 14-h and 16-h to induce transition from vegetative to floral stages in development. PPF and daily absorbed photons did not affect time to vegetative / floral stage transition, but did affect factors such as biomass accumulation and canopy parameters such as specific leaf mass. Reciprocal exchange of plants between floral inducing and inhibiting photoperiod treatments, starting at 2-weeks post germination, had no effect on to flower. Flowering was determined by photoperiod experienced during the first 2-weeks (or less) post germination. Yellow Starthistle net photosynthetic response to elevated atmospheric CO2 concentrations over a range of photosynthetically active radiation flux rates and temperatures will also be presented and discussed.

  16. Metabolic Response of Dungeness Crab Larvae Exposed to Elevated CO2 and Hypoxia

    Science.gov (United States)

    Nichols, Z.; Busch, S.; McElhany, P.

    2015-12-01

    Ocean acidification (OA) and deoxygenation, both resulting from rising atmospheric CO2 levels, are lowering the pH and oxygen levels of global oceans. Assessing the impacts of OA and deoxygenation on harvested species is crucial for guiding resource management with the aim of maintaining healthy and sustainable populations. The Dungeness crab, Cancer magister, is an important species ecologically and economically for the US West Coast. Crabs transition through four main stages: zoea, megalopa, juvenile, and adult. Each stage results in a different morphology and behavior, and as a result, is exposed to various environmental parameters, such as pH and dissolved oxygen (DO). The first two stages exhibit diel vertical migration while the final stages are benthic. Our study focused on the megalopae stage and their metabolic response to OA and hypoxia. We exposed wild-caught megalopae to a pH x DO cross, producing treatment waters with combinations of low or high pH and O2, all maintained at 12˚C. Closed-chamber respirometry was used to compare standard metabolic rates in a common garden setting with high pH/high DO conditions. We predict that the megalopae exposed to the low pH/high DO treatment will have a higher metabolic rate than those exposed to the high pH/high DO treatment. This may be a result of homeostatic processes increasing to return the megalopae's internal pH back to equilibrium. We predict that the high pH/low DO treatment will cause a decrease in metabolism when compared to the high pH/high DO treatment due to the megalopae conserving oxygen in a limiting environment. If results support our hypothesis, they would suggest that OA and hypoxia affects Dungeness crabs in sublethal ways.

  17. Discussion of Yellow Starthistle Response to Photosynthetic Irradiance, Photoperiod, and CO2

    Science.gov (United States)

    Bubenheim, David

    2017-01-01

    Yellow Starthistle (Centaurea solstitialis) is a native annual weed of Eurasia and since introduction into the United STates has become an invasive and noxious weed. It grows in a rosette habit during the vegetative state and usually bolts in summer to produce a large and branched flowering stem. Time to flowering in Yellow Starthistle has been attributed to photoperiod, nitrogen nutrition, temperature, and water stress. We executed a series of studies to investigate the role of light, both photoperiod and photosynthetic photon flux, on flowering and development in Yellow Starthistle. Treatments were presented in 4 ways: 1) varying day length with constant photosynthetic photon flus (PPF) providing increasing daily integrated Photosynthetic Photon (PP) exposure with longer day lengths 2) varying day length while adjusting PPF to maintain daily PP exposure for all treatments 3) extending photoperiod treatments beyond common 12-h photosynthetic period with low light levels to maintain both PPF and daily PP across all treatments4)reciprocal exchange of plant among photoperiod treatments Yellow Starthistle appears to be a long-day plant with a critical day length requirement between 14-h and 16-h to induce transition from vegetative to floral stages in development. PPF and daily absorbed photons did not affect time to vegetative floral stage transition, but did affect factors such as biomass accumulation and canopy parameters such as specific leaf mass. Reciprocal exchange of plants between floral inducing and inhibiting photoperiod treatments, starting at 2-weeks post germination, had no effect on to flower. Flowering was determined by photoperiod experienced during the first 2-weeks (or less) post germination.Yellow Starthistle net photosynthetic response to elevated atmospheric CO2 concentrations over a range of photosynthetically active radiation flux rates and temperatures will also be presented and discussed.

  18. Systemic to Microscale Response of Orbicella faveolata to Future Ocean CO2 Conditions.

    Science.gov (United States)

    Dungan, A.; Hall, E. R.; Blackwelder, P. L.; Fogarty, N. D.

    2016-02-01

    Coral reefs are one of the most economically important ecosystems on the planet, supplying roughly $30 billion USD annually into world economies from the goods and services they provide. Despite their great contributions, anthropogenic influence via carbon dioxide emissions is leading to unprecedented changes in the tropical oceans with concerns about subsequent negative impacts on reefs. Surface ocean pH has dropped 0.1 units in the past century, representing a thirty percent increase in hydrogen ion concentration. In spite of this rapid shift in oceanic chemistry, it is unclear how adult corals and their new recruits will be impacted. In this experiment we examined the relationship between CO2-induced seawater acidification, net calcification, and physiological parameters in Orbicella faveolata adults and new recruits under ambient (465 ± 5.52 ppm), and high (1451 ± 6.51 ppm) CO2 conditions. These treatments represented current and end of the century CO2 values predicted under the RCP8.5 scenario developed by the Intergovernmental Panel on Climate Change (IPCC). Electron microscopy (TEM/SEM) was used to examine coral cellular ultrastructure and newly formed aragonite skeletal crystal structures. Orbicella faveolata exhibited no significant difference in skeletal deposition rates under control and high CO2 conditions; however, crystal formations for both adult and juvenile O. faveolata were statistically longer in the high CO2 treatment. No significant differences were seen in photosynthesis or respiration rates. These results suggest that the addition of CO2 may cause a shift in the overall energy budgets causing a modification of skeletal aragonite crystal structures, rather than inhibiting skeletal crystal formation. Consequential to this energy shift, Orbicella faveolata belongs in the category of Scleractinian corals that exhibit a low sensitivity to ocean acidification and existing colonies may continue to calcify and build reefs in the face of ocean

  19. Growth CO2 concentration modifies the transpiration response of Populus deltoides to drought and vapor pressure deficit.

    Science.gov (United States)

    Engel, Victor C; Griffin, Kevin L; Murthy, Ramesh; Patterson, Lane; Klimas, Christie; Potosnak, Mark

    2004-10-01

    Cottonwood (Populus deltoides Bartr. ex Marsh.) trees grown for 9 months in elevated carbon dioxide concentration ([CO2]) showed significant increases in height, leaf area and basal diameter relative to trees in a near-ambient [CO2] control treatment. Sample trees in the CO2 treatments were subjected to high and low atmospheric vapor pressure deficits (VPD) over a 5-week period at both high and low soil water contents (SWC). During these periods, transpiration rates at both the leaf and canopy levels were calculated based on sap flow measurements and leaf-to-sapwood area ratios. Leaf-level transpiration rates were approximately equivalent across [CO2] treatments when soil water was not limiting. In contrast, during drought stress, canopy-level transpiration rates were approximately equivalent across [CO2] treatments, indicating that leaf-level fluxes during drought stress were reduced in elevated [CO2] by a factor equal to the leaf area ratio of the two canopies. The shift from equivalent leaf-level transpiration to equivalent canopy-level transpiration with increasing drought stress suggests maximum water use rates were controlled primarily by atmospheric demand at high SWC and by soil water availability at low SWC. Changes in VPD had less effect on transpiration than changes in SWC for trees in both CO2 treatments. Transpiration rates of trees in both CO2 treatments reached maximum values at a VPD of about 2.0 kPa at high SWC, but leveled off and decreased slightly in both canopies as VPD increased above this value. At low SWC, increasing VPD from approximately 1.4 to 2.5 kPa caused transpiration rates to decline slightly in the canopies of trees in both treatments, with significant (P = 0.004) decreases occurring in trees in the near-ambient [CO2] treatment. The transpiration responses at high VPD in the presence of high SWC and throughout the low SWC treatment suggest some hydraulic limitations to water use occurred. Comparisons of midday leaf water potentials

  20. Species-Specific Responses of Juvenile Rockfish to Elevated pCO2: From Behavior to Genomics.

    Directory of Open Access Journals (Sweden)

    Scott L Hamilton

    Full Text Available In the California Current ecosystem, global climate change is predicted to trigger large-scale changes in ocean chemistry within this century. Ocean acidification-which occurs when increased levels of atmospheric CO2 dissolve into the ocean-is one of the biggest potential threats to marine life. In a coastal upwelling system, we compared the effects of chronic exposure to low pH (elevated pCO2 at four treatment levels (i.e., pCO2 = ambient [500], moderate [750], high [1900], and extreme [2800 μatm] on behavior, physiology, and patterns of gene expression in white muscle tissue of juvenile rockfish (genus Sebastes, integrating responses from the transcriptome to the whole organism level. Experiments were conducted simultaneously on two closely related species that both inhabit kelp forests, yet differ in early life history traits, to compare high-CO2 tolerance among species. Our findings indicate that these congeners express different sensitivities to elevated CO2 levels. Copper rockfish (S. caurinus exhibited changes in behavioral lateralization, reduced critical swimming speed, depressed aerobic scope, changes in metabolic enzyme activity, and increases in the expression of transcription factors and regulatory genes at high pCO2 exposure. Blue rockfish (S. mystinus, in contrast, showed no significant changes in behavior, swimming physiology, or aerobic capacity, but did exhibit significant changes in the expression of muscle structural genes as a function of pCO2, indicating acclimatization potential. The capacity of long-lived, late to mature, commercially important fish to acclimatize and adapt to changing ocean chemistry over the next 50-100 years is likely dependent on species-specific physiological tolerances.

  1. Can current moisture responses predict soil CO2 efflux under altered precipitation regimes? A synthesis of manipulation experiments

    Science.gov (United States)

    S. Vicca; M. Bahn; M. Estiarte; E. E. van Loon; R. Vargas; G. Alberti; P. Ambus; M. A. Arain; C. Beier; L. P. Bentley; W. Borken; N. Buchmann; S. L. Collins; G. de Dato; J. S. Dukes; C. Escolar; P. Fay; G. Guidolotti; P. J. Hanson; A. Kahmen; G. Kröel-Dulay; T. Ladreiter-Knauss; K. S. Larsen; E. Lellei-Kovacs; E. Lebrija-Trejos; F. T. Maestre; S. Marhan; M. Marshall; P. Meir; Y. Miao; J. Muhr; P. A. Niklaus; R. Ogaya; J. Peñuelas; C. Poll; L. E. Rustad; K. Savage; A. Schindlbacher; I. K. Schmidt; A. R. Smith; E. D. Sotta; V. Suseela; A. Tietema; N. van Gestel; O. van Straaten; S. Wan; U. Weber; I. A. Janssens

    2014-01-01

    As a key component of the carbon cycle, soil CO2 efflux (SCE) is being increasingly studied to improve our mechanistic understanding of this important carbon flux. Predicting ecosystem responses to climate change often depends an extrapolation of current relationships between ecosystem processes and their climatic drivers to conditions not yet experienced by the...

  2. Evaluating the responses of forest ecosystems to climate change and CO2 using dynamic global vegetation models

    OpenAIRE

    Song, Xiang; Zeng, Xiaodong

    2017-01-01

    Abstract The climate has important influences on the distribution and structure of forest ecosystems, which may lead to vital feedback to climate change. However, much of the existing work focuses on the changes in carbon fluxes or water cycles due to climate change and/or atmospheric CO 2, and few studies have considered how and to what extent climate change and CO 2 influence the ecosystem structure (e.g., fractional coverage change) and the changes in the responses of ecosystems with diffe...

  3. INTERSPECIFIC VARIATION IN THE GROWTH-RESPONSE OF PLANTS TO AN ELEVATED AMBIENT CO2 CONCENTRATION

    NARCIS (Netherlands)

    POORTER, H

    The effect of a doubling in the atmospheric CO2 concentration on the growth of vegetative whole plants was investigated. In a compilation of literature sources, the growth stimulation of 156 plant species was found to be on average 37%. This enhancement is small compared to what could be expected on

  4. Shifting carbon flow from roots into associated microbial communities in response to elevated atmospheric CO2

    NARCIS (Netherlands)

    Drigo, B.; Pijl, A.S.; Duyts, H.; Kielak, A.M.; Gamper, H.A.; Houtekamer, M.J.; Boschker, H.T.S.; Bodelier, P.L.E.; Whiteley, A.S.; Van Veen, J.A.; Kowalchuk, G.A.

    2010-01-01

    Rising atmospheric CO2 levels are predicted to have major consequences on carbon cycling and the functioning of terrestrial ecosystems. Increased photosynthetic activity is expected, especially for C-3 plants, thereby influencing vegetation dynamics; however, little is known about the path of fixed

  5. Increasing sugar transport to improve soybean response to elevated [CO2

    Science.gov (United States)

    Elevated atmospheric [CO2] causes a direct increase in instantaneous photosynthesis and sugar production in C3 plants, leading to a yield increase which is promising to meet future food demand. However, previous studies have shown that soybean yield does not increase as much as predicted under eleva...

  6. Is phloem loading a driver of plant photosynthetic responses to elevated atmospheric [CO2]? 

    Science.gov (United States)

    A better understanding of the interactions between photosynthesis, photoassimilate translocation and sink activity is necessary to improve crop productivity. Rising atmospheric [CO2] is perturbing source-sink balance in a manner not experienced by crops during the history of their cultivation, so ne...

  7. Modelling the response of wheat canopy assimilation to atmospheric CO2 concentrations.

    NARCIS (Netherlands)

    Rodriguez, D.; Ewert, F.; Goudriaan, J.; Manderscheid, R.; Burkart, S.; Weigel, H.J.

    2001-01-01

    The predictive capacity of two simulation models with different degrees of complexity for the calculation of assimilate production, was tested at different time scales, using a data set of wheat grown in an open-top-chamber experiment at two CO2 concentrations. Observed values of net canopy

  8. Effect of CO2 milliwatt laser on peripheral nerves: Part I. A dose-response study

    NARCIS (Netherlands)

    Menovsky, T.; van den Bergh Weerman, M.; Beek, J. F.

    1996-01-01

    In order to explore further the role of laser for microneural repair, the effect of CO2 laser irradiation on intact rat sciatic nerves was investigated. In total 40 rat sciatic nerves were exposed to 12 different combinations of laser power (50, 100, and 150 mW) and pulse duration (0.1 to 3 s)

  9. Response of CO2 exchange in a tussock tundra ecosystem to permafrost thaw and thermokarst development

    Science.gov (United States)

    Jason Vogel; Edward A.G. Schuur; Christian Trucco; Hanna. Lee

    2009-01-01

    Climate change in high latitudes can lead to permafrost thaw, which in ice-rich soils can result in ground subsidence, or thermokarst. In interior Alaska, we examined seasonal and annual ecosystem CO2 exchange using static and automatic chamber measurements in three areas of a moist acidic tundra ecosystem undergoing varying degrees of permafrost...

  10. A statistical analysis of three ensembles of crop model responses to temperature and CO2 concentration

    Science.gov (United States)

    Ensembles of process-based crop models are now commonly used to simulate crop growth and development for climate scenarios of temperature and/or precipitation changes corresponding to different projections of atmospheric CO2 concentrations. This approach generates large datasets with thousands of de...

  11. Variable responses to CO2 of the duration of vegetative growth within maturity group IV soybeans

    Science.gov (United States)

    Prior experiments in indoor chambers and in the field using free-air carbon dioxide enrichment (FACE) systems indicated variation among soybean cultivars in whether and how much elevated CO2 prolonged vegetative development. However, the cultivars tested differed in maturity group, and it is not kn...

  12. [Optimization for supercritical CO2 extraction with response surface methodology and component analysis of Sapindus mukorossi oil].

    Science.gov (United States)

    Wu, Yan; Xiao, Xin-yu; Ge, Fa-huan

    2012-02-01

    To study the extraction conditions of Sapindus mukorossi oil by Supercritical CO2 Extraction and identify its components. Optimized SFE-CO2 Extraction by response surface methodology and used GC-MS to analysie Sapindus mukorossi oil compounds. Established the model of an equation for the extraction rate of Sapindus mukorossi oil by Supercritical CO2 Extraction, and the optimal parameters for the Supercritical CO2 Extraction determined by the equation were: the extraction pressure was 30 MPa, temperature was 40 degrees C; The separation I pressure was 14 MPa, temperature was 45 degrees C; The separation II pressure was 6 MPa, temperature was 40 degrees C; The extraction time was 60 min and the extraction rate of Sapindus mukorossi oil of 17.58%. 22 main compounds of Sapindus mukorossi oil extracted by supercritical CO2 were identified by GC-MS, unsaturated fatty acids were 86.59%. This process is reliable, safe and with simple operation, and can be used for the extraction of Sapindus mukorossi oil.

  13. A linear fluorescence-quenching response in an amidine-functionalised solid-state sensor for gas-phase and aqueous CO2 detection.

    Science.gov (United States)

    Das, A; D'Alessandro, D M

    2016-04-28

    An amidine-functionalised metal-organic framework (MOF) was shown to be an effective chemosensor in the presence of gaseous and aqueous phase CO2 by virtue of a quenched fluorescence response. This work demonstrates how multifunctional MOFs with high selectivity for CO2 may be exploited to develop CO2 chemosensors.

  14. Lowering of glacial atmospheric CO2 in response to changes in oceanic circulation and marine biogeochemistry

    Science.gov (United States)

    Brovkin, Victor; Ganopolski, Andrey; Archer, David; Rahmstorf, Stefan

    2007-12-01

    We use an Earth system model of intermediate complexity, CLIMBER-2, to investigate what recent improvements in the representation of the physics and biology of the glacial ocean imply for the atmospheric concentration. The coupled atmosphere-ocean model under the glacial boundary conditions is able to reproduce the deep, salty, stagnant water mass inferred from Antarctic deep pore water data and the changing temperature of the entire deep ocean. When carbonate compensation is included in the model, we find a CO2 drawdown of 43 ppmv associated mainly with the shoaling of the Atlantic thermohaline circulation and an increased fraction of water masses of southern origin in the deep Atlantic. Fertilizing the Atlantic and Indian sectors of the Southern Ocean north of the polar front leads to a further drawdown of 37 ppmv. Other changes to the glacial carbon cycle include a decrease in the amount of carbon stored in the terrestrial biosphere (540 Pg C), which increases atmospheric CO2 by 15 ppmv, and a change in ocean salinity resulting from a drop in sea level, which elevates CO2 by another 12 ppmv. A decrease in shallow water CaCO3 deposition draws down CO2 by 12 ppmv. In total, the model is able to explain more than two thirds (65 ppmv) of the glacial to interglacial CO2 change, based only on mechanisms that are clearly documented in the proxy data. A good match between simulated and reconstructed distribution of δ13C changes in the deep Atlantic suggests that the model captures the mechanisms of reorganization of biogeochemistry in the Atlantic Ocean reasonably well. Additional, poorly constrained mechanisms to explain the rest of the observed drawdown include changes in the organic carbon:CaCO3 ratio of sediment rain reaching the seafloor, iron fertilization in the subantarctic Pacific Ocean, and changes in terrestrial weathering.

  15. Cardiac and ventilatory responses of Crangon crangon to cadmium, copper and zinc

    Science.gov (United States)

    Price, R. K. J.; Uglow, R. F.

    1980-03-01

    The acute (30 min) responses of heart and scaphognathite activities of Crangon crangon on exposure to concentrations of 1 20 mg Cd, Cu or Zn 1-1 are increased beat frequencies. The relative magnitude of response (Δ f) is linearly related to immediate pretreatment frequency (f) and standardised responses (Δ fs) are given for f values of 70 and 100 beats min-1 for hearts and scaphognathites, respectively. Δ fs values for each organ are also linearly related to test concentration for each metal. Qualitative changes to organ activities described include an increased incidence of scaphognathite reversals in concentrations of 5.0 mg Cu 1-1 and in 20.0 mg Zn 1-1. Chronic (13 days) exposure to incipient lethal levels of the test metals produced increases in scaphognathite rates of the Cd-treated animals and in heart and scaphognathite rates of the coppertreated animals. The general applicability of these methods to studies of pollution stress in decapods is discussed.

  16. Cardiac and ventilatory responses of Crangon crangon to cadmium, copper and zinc

    Energy Technology Data Exchange (ETDEWEB)

    Price, R.K.J.; Uglow, R.F.

    1980-01-01

    The acute (30 min) responses of heart and scaphognathite activities of Crangon crangon on exposure to concentrations of 1-20 mg Cd, Cu or Zn 1/sup -1/ are increased beat frequencies. The relative magnitude of response (..delta..f) is linearly related to immediate pretreatment frequency (f) and standardised responses (..delta..fs) are given for f values of 70 and 100 beats min/sup -1/ for hearts and scaphoganthites, respectively. ..delta..fs values for each organ are also linearly related to test concentration for each metal. Qualitative changes to organ activities described include an increased incidence of scaphognathite reversals in concentrations of 5.0 mg Cu 1/sup -1/ and in 20.0 mg Zn 1/sup -1/. Chronic (13 days) exposure to incipient lethal levels of the test metals produced increases in scaphognathite rates of the Cd-treated animals and in heart and scaphognathite rates of the coppertreated animals. The general applicability of these methods to studies of pollution stress in decapods is discussed.

  17. Prevalence of Ventilatory Conditions for Dynamic Fluid Responsiveness Prediction in 2 Tertiary Intensive Care Units.

    Science.gov (United States)

    Mendes, Pedro V; Rodrigues, Bruno N; Miranda, Leandro C; Zampieri, Fernando G; Queiroz, Eduardo L; Schettino, Guilherme; Azevedo, Luciano C; Park, Marcelo; Taniguchi, Leandro U

    2016-05-01

    Dynamic parameters for fluid responsiveness obtained from heart-lung interaction during invasive mechanical ventilation require specific conditions not always present in intensive care unit (ICU) patients. The aim of this study was to examine the prevalence of these conditions in critically ill patients. We conducted a prospective observational study in 2 medical-surgical ICUs. We evaluated whether it would be possible to measure dynamic indices of fluid responsiveness when fluid expansion was administered. We recorded whether the patients were in controlled invasive mechanical ventilation with tidal volume >8 mL/kg and without arrhythmias. The proportion of patients who fulfilled these conditions was recorded. A post hoc subgroup analyses by terciles of Simplified Acute Physiology Score 3 (SAPS3) were performed. A total of 826 fluid challenges were undertaken in 424 patients during the study. The use of controlled mechanical ventilation with tidal volume > 8 mL/kg and without arrhythmias occurred in only 2.9% of the patients at the time of fluid challenge episodes. There was an increase in the prevalence of these conditions as the severity of the patients also increased: lower tercile of SAPS3 (0%), intermediate tercile (2%), and higher tercile (6.9%; P parameters for predicting fluid responsiveness in ICU may have restricted applicability in daily practice, even in more severe patients, due to low prevalence of required conditions. © The Author(s) 2014.

  18. Changes in the activities of starch metabolism enzymes in rice grains in response to elevated CO2 concentration.

    Science.gov (United States)

    Xie, Li-Yong; Lin, Er-Da; Zhao, Hong-Liang; Feng, Yong-Xiang

    2016-05-01

    The global atmospheric CO(2) concentration is currently (2012) 393.1 μmol mol(-1), an increase of approximately 42 % over pre-industrial levels. In order to understand the responses of metabolic enzymes to elevated CO(2) concentrations, an experiment was conducted using the Free Air CO(2) Enrichment (FACE )system. Two conventional japonica rice varieties (Oryza sativa L. ssp. japonica) grown in North China, Songjing 9 and Daohuaxiang 2, were used in this study. The activities of ADPG pyrophosphorylase, soluble and granule-bound starch synthases, and soluble and granule-bound starch branching enzymes were measured in rice grains, and the effects of elevated CO(2) on the amylose and protein contents of the grains were analyzed. The results showed that elevated CO(2) levels significantly increased the activity of ADPG pyrophosphorylase at day 8, 24, and 40 after flower, with maximum increases of 56.67 % for Songjing 9 and 21.31 % for Daohuaxiang 2. Similarly, the activities of starch synthesis enzymes increased significantly from the day 24 after flower to the day 40 after flower, with maximum increases of 36.81 % for Songjing 9 and 66.67 % for Daohuaxiang 2 in soluble starch synthase (SSS), and 25.00 % for Songjing 9 and 36.44 % for Daohuaxiang 2 in granule-bound starch synthase (GBSS), respectively. The elevated CO(2) concentration significantly increased the activity of soluble starch branching enzyme (SSBE) at day 16, 32, and 40 after flower, and also significantly increased the activity of granule-bound starch branching enzyme (GBSBE) at day 8, 32, and 40 after flower. The elevated CO(2) concentration increased the peak values of enzyme activity, and the timing of the activity peaks for SSS and GBSBE were earlier in Songjing 9 than in Daohuaxiang 2. There were obvious differences in developmental stages between the two varieties of rice, which indicated that the elevated CO(2) concentration increased enzyme activity expression and starch synthesis, affecting the

  19. Neurochemical and electrical modulation of the Locus coeruleus: contribution to CO2 drive to breathe

    Directory of Open Access Journals (Sweden)

    Debora eDe Carvalho

    2014-08-01

    Full Text Available The Locus coeruleus (LC is a dorsal pontine region, situated bilaterally on the floor of the fourth ventricle. It is considered to be the major source of noradrenergic innervation in the brain. These neurons are highly sensitive to CO2 / pH, and chemical lesions of LC neurons largely attenuate the hypercapnic ventilatory response in unanesthetized adult rats. Developmental dysfunctions in these neurons are linked to pathological conditions such as Rett and sudden infant death syndromes, which can impair the control of the cardio-respiratory system. LC is densely innervated by fibers that contain glutamate, serotonin and ATP, and these neurotransmitters strongly affect LC activity, including central chemoreflexes. Aside from neurochemical modulation, LC neurons are also strongly electrically coupled, specifically through gap junctions, which play a role in the CO2 ventilatory response. This article reviews the available data on the role of chemical and electrical neuromodulation of the LC in the control of ventilation.

  20. Intermittent hypercapnic hypoxia during sleep does not induce ventilatory long-term facilitation in healthy males.

    Science.gov (United States)

    Deacon, Naomi L; McEvoy, R Doug; Stadler, Daniel L; Catcheside, Peter G

    2017-09-01

    Intermittent hypoxia-induced ventilatory neuroplasticity is likely important in obstructive sleep apnea pathophysiology. Although concomitant CO2 levels and arousal state critically influence neuroplastic effects of intermittent hypoxia, no studies have investigated intermittent hypercapnic hypoxia effects during sleep in humans. Thus the purpose of this study was to investigate if intermittent hypercapnic hypoxia during sleep induces neuroplasticity (ventilatory long-term facilitation and increased chemoreflex responsiveness) in humans. Twelve healthy males were exposed to intermittent hypercapnic hypoxia (24 × 30 s episodes of 3% CO2 and 3.0 ± 0.2% O2) and intermittent medical air during sleep after 2 wk washout period in a randomized crossover study design. Minute ventilation, end-tidal CO2, O2 saturation, breath timing, upper airway resistance, and genioglossal and diaphragm electromyograms were examined during 10 min of stable stage 2 sleep preceding gas exposure, during gas and intervening room air periods, and throughout 1 h of room air recovery. There were no significant differences between conditions across time to indicate long-term facilitation of ventilation, genioglossal or diaphragm electromyogram activity, and no change in ventilatory response from the first to last gas exposure to suggest any change in chemoreflex responsiveness. These findings contrast with previous intermittent hypoxia studies without intermittent hypercapnia and suggest that the more relevant gas disturbance stimulus of concomitant intermittent hypercapnia frequently occurring in sleep apnea influences acute neuroplastic effects of intermittent hypoxia. These findings highlight the need for further studies of intermittent hypercapnic hypoxia during sleep to clarify the role of ventilatory neuroplasticity in the pathophysiology of sleep apnea.NEW & NOTEWORTHY Both arousal state and concomitant CO2 levels are known modulators of the effects of intermittent hypoxia on

  1. Analysis of Pacific oyster larval proteome and its response to high-CO2

    KAUST Repository

    Dineshram, R.

    2012-10-01

    Most calcifying organisms show depressed metabolic, growth and calcification rates as symptoms to high-CO2 due to ocean acidification (OA) process. Analysis of the global expression pattern of proteins (proteome analysis) represents a powerful tool to examine these physiological symptoms at molecular level, but its applications are inadequate. To address this knowledge gap, 2-DE coupled with mass spectrophotometer was used to compare the global protein expression pattern of oyster larvae exposed to ambient and to high-CO2. Exposure to OA resulted in marked reduction of global protein expression with a decrease or loss of 71 proteins (18% of the expressed proteins in control), indicating a wide-spread depression of metabolic genes expression in larvae reared under OA. This is, to our knowledge, the first proteome analysis that provides insights into the link between physiological suppression and protein down-regulation under OA in oyster larvae. © 2012 Elsevier Ltd.

  2. Effect of CO2, nutrients and light on coastal plankton. I. Abiotic conditions and biological responses

    Czech Academy of Sciences Publication Activity Database

    Neale, P.J.; Sobrino, C.; Segovia, M.; Mercado, J.M.; Leon, P.; Cortés, M.D.; Tuite, P.; Picazo, A.; Salles, S.; Cabrerizo, M.J.; Prášil, Ondřej; Montecino, V.; Reul, A.; Fuentes-Lema, A.

    2014-01-01

    Roč. 22, č. 2 (2014), s. 25-41 ISSN 1864-7790 R&D Projects: GA MŠk ED2.1.00/03.0110 Grant - others:Univ. Málaga(ES) Program Plan Propio; NASA(US) NNX09AM85G Institutional support: RVO:61388971 Keywords : phytoplankton * nutrients * CO2 * irradiance Subject RIV: EE - Microbiology, Virology Impact factor: 1.258, year: 2014

  3. Assessment of aerobic capacity through blood and ventilatory responses in four different ergometers

    Directory of Open Access Journals (Sweden)

    Alessandro Moura Zagatto

    2013-04-01

    Full Text Available The objective of the study was to compare intensities of respiratory compensation point (RCP,anaerobic threshold at onset blood lactate accumulation (OBLA3,5, and anaerobic threshold at lactate abrupt increase (AnTLAC determined in four different ergometers. Hence, eleven table tennis players (19±1 years performed graded exercise tests on cycle ergometer, arm cranking ergometer, treadmill and specific table tennis test. The respiratory response and lactatemia were measured during the tests. We did not find significant diferences among RCP, AnTLAC and OBLA3,5 in arm cranking ergometer (63.4±4.8W, 66.9±4.5W and 64.5±6.1W, respectively, treadmill (11.4±0.4 km.h-1, 11.3±0.3 km.h-1 and 11.1±0.3 km.h-1, respectively, and specific table tennis test (40.5±1.8 bolas.min-1, 42.6±3.6bolas.min-1 and 42.8±5.6bolas.min-1,respectively. However, the OBLA 3,5 (131.9±6.6W was significantly lower than RCP (149.3±4.9W and AnTLAC (149.3±4.7W in the cycle ergometer. Strong and significant correlation coefficients were found in the specific test for all methods (r range 0.83 to 0.95, in arm cranking ergometer between RCP and OBLA 3,5 (r=0.78, and on treadmill running between OBLA3,5 and AnTLAC (r=0.76.Therefore, we conclude that RCP, OBLA3,5 and AnTLAC seem to correspond to the same physiological phenomenon, mostly during specific table tennis test.

  4. Temperature and the Ventilatory Response to Hypoxia in Gromphadorhina portentosa (Blattodea: Blaberidae).

    Science.gov (United States)

    Harrison, Jon F; Manoucheh, Milad; Klok, C Jaco; Campbell, Jacob B

    2016-04-01

    In general, insects respond to hypoxia by increasing ventilation frequency, as seen in most other animals. Higher body temperatures usually also increase ventilation rates, likely due to increases in metabolic rates. In ectothermic air-breathing vertebrates, body temperatures and hypoxia tend to interact significantly, with an increasing responsiveness of ventilation to hypoxia at higher temperatures. Here, we tested whether the same is true in insects, using the Madagascar hissing cockroach, Gromphadorhina portentosa (Schaum) (Blattodea: Blaberidae). We equilibrated individuals to a temperature (beginning at 20 °C), and animals were exposed to step-wise decreases in PO2 (21, 15, 10, and 5 kPa, in that order), and we measured ventilation frequencies from videotapes of abdominal pumping after 15 min of exposure to the test oxygen level. We then raised the temperature by 5 °C, and the protocol was repeated, with tests run at 20, 25, 30, and 35 °C. The 20 °C animals had high initial ventilation rates, possibly due to handling stress, so these animals were excluded from subsequent analyses. Across all temperatures, ventilation increased in hypoxia, but only significantly at 5 kPa PO2 Surprisingly, there was no significant interaction between temperature and oxygen, and no significant effect of temperature on ventilation frequency from 25 to 35 °C. Plausibly, the rise in metabolic rates at higher temperatures in insects is made possible by increasing other aspects of gas exchange, such as decreasing internal PO2, or increases in tidal volume, spiracular opening (duration or amount), or removal of fluid from the tracheoles. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  5. Analysis of QTLs for Flag Leaf Shape and Its Response to Elevated CO2 in Rice (Oryza sativa

    Directory of Open Access Journals (Sweden)

    Gui-zhi FAN

    2007-03-01

    Full Text Available To understand the responses of flag leaf shape in rice to elevated CO2 environment and their genetic characteristics, quantitative trait loci (QTLs for flag leaf shape in rice were mapped onto the molecular marker linkage map of chromosome segment substitution lines (CSSLs derived from a cross between a japonica variety Asominori and an indica variety IR24 under free air carbon dioxide enrichment (FACE, 200 μmol/mol above current levels and current CO2 concentration (Ambient, about 370 μmol/mol. Three flag-leaf traits, flag-leaf length (LL, width (LW and the ratio of LL to LW (RLW, were estimated for each CSSL and their parental varieties. The differences in LL, LW and RLW between parents and in LL and LW within IR24 between FACE and Ambient were significant at 1% level. The continuous distributions and transgressive segregations of LL, LW and RLW were also observed in CSSL population, showing that the three traits were quantitatively inherited under both FACE and Ambient. A total of 16 QTLs for the three traits were detected on chromosomes 1, 2, 3, 4, 6, 8 and 11 with LOD (Log10-likelihood ratio scores ranging from 3.0 to 6.7. Among them, four QTLs (qLL-6*, qLL-8*, qLW-4*, and qRLW-6* were commonly detected under both FACE and Ambient. Therefore, based on the different responses to elevated CO2 in comparison with current CO2 level, it can be suggested that the expressions of several QTLs associated with flag-leaf shape in rice could be induced by the high CO2 level.

  6. Response and adaptation of photosynthesis, respiration, and antioxidant systems to elevated CO2 with environmental stress in plants

    Directory of Open Access Journals (Sweden)

    Zhenzhu eXu

    2015-09-01

    Full Text Available It is well known that plant photosynthesis and respiration are two fundamental and crucial physiological processes, while the critical role of the antioxidant system in response to abiotic factors is still a focus point for investigating physiological stress. Although one key metabolic process and its response to climatic change have already been reported and reviewed, an integrative review, including several biological processes at multiple scales, has not been well reported. The current review will present a synthesis focusing on the underlying mechanisms in the responses to elevated CO2 at multiple scales, including molecular, cellular, biochemical, physiological, and individual aspects, particularly, for these biological processes under elevated CO2 with other key abiotic stresses, such as heat, drought, and ozone pollution, as well as nitrogen limitation. The present comprehensive review may add timely and substantial information about the topic in recent studies, while it presents what has been well established in previous reviews. First, an outline of the critical biological processes, and an overview of their roles in environmental regulation, is presented. Second, the research advances with regard to the individual subtopics are reviewed, including the response and adaptation of the photosynthetic capacity, respiration, and antioxidant system to CO2 enrichment alone, and its combination with other climatic change factors. Finally, the potential applications for plant responses at various levels to climate change are discussed. The above issue is currently of crucial concern worldwide, and this review may help in a better understanding of how plants deal with elevated CO2 using other mainstream abiotic factors, including molecular, cellular, biochemical, physiological, and whole individual processes, and the better management of the ecological environment, climate change, and sustainable development.

  7. Response and adaptation of photosynthesis, respiration, and antioxidant systems to elevated CO2 with environmental stress in plants.

    Science.gov (United States)

    Xu, Zhenzhu; Jiang, Yanling; Zhou, Guangsheng

    2015-01-01

    It is well known that plant photosynthesis and respiration are two fundamental and crucial physiological processes, while the critical role of the antioxidant system in response to abiotic factors is still a focus point for investigating physiological stress. Although one key metabolic process and its response to climatic change have already been reported and reviewed, an integrative review, including several biological processes at multiple scales, has not been well reported. The current review will present a synthesis focusing on the underlying mechanisms in the responses to elevated CO2 at multiple scales, including molecular, cellular, biochemical, physiological, and individual aspects, particularly, for these biological processes under elevated CO2 with other key abiotic stresses, such as heat, drought, and ozone pollution, as well as nitrogen limitation. The present comprehensive review may add timely and substantial information about the topic in recent studies, while it presents what has been well established in previous reviews. First, an outline of the critical biological processes, and an overview of their roles in environmental regulation, is presented. Second, the research advances with regard to the individual subtopics are reviewed, including the response and adaptation of the photosynthetic capacity, respiration, and antioxidant system to CO2 enrichment alone, and its combination with other climatic change factors. Finally, the potential applications for plant responses at various levels to climate change are discussed. The above issue is currently of crucial concern worldwide, and this review may help in a better understanding of how plants deal with elevated CO2 using other mainstream abiotic factors, including molecular, cellular, biochemical, physiological, and whole individual processes, and the better management of the ecological environment, climate change, and sustainable development.

  8. Polygonal tundra geomorphological change in response to warming alters future CO2 and CH4 flux on the Barrow Peninsula

    Science.gov (United States)

    Lara, Mark J.; McGuire, A. David; Euskirchen, Eugénie S.; Tweedie, Craig E.; Hinkel, Kenneth M.; Skurikhin, Alexei N.; Romanovsky, Vladimir E.; Grosse, Guido; Bolton, W. Robert; Genet, Helene

    2015-01-01

    The landscape of the Barrow Peninsula in northern Alaska is thought to have formed over centuries to millennia, and is now dominated by ice-wedge polygonal tundra that spans drained thaw-lake basins and interstitial tundra. In nearby tundra regions, studies have identified a rapid increase in thermokarst formation (i.e., pits) over recent decades in response to climate warming, facilitating changes in polygonal tundra geomorphology. We assessed the future impact of 100 years of tundra geomorphic change on peak growing season carbon exchange in response to: (i) landscape succession associated with the thaw-lake cycle; and (ii) low, moderate, and extreme scenarios of thermokarst pit formation (10%, 30%, and 50%) reported for Alaskan arctic tundra sites. We developed a 30 × 30 m resolution tundra geomorphology map (overall accuracy:75%; Kappa:0.69) for our ~1800 km² study area composed of ten classes; drained slope, high center polygon, flat-center polygon, low center polygon, coalescent low center polygon, polygon trough, meadow, ponds, rivers, and lakes, to determine their spatial distribution across the Barrow Peninsula. Land-atmosphere CO2 and CH4 flux data were collected for the summers of 2006–2010 at eighty-two sites near Barrow, across the mapped classes. The developed geomorphic map was used for the regional assessment of carbon flux. Results indicate (i) at present during peak growing season on the Barrow Peninsula, CO2 uptake occurs at -902.3 106gC-CO2 day−1(uncertainty using 95% CI is between −438.3 and −1366 106gC-CO2 day−1) and CH4 flux at 28.9 106gC-CH4 day−1(uncertainty using 95% CI is between 12.9 and 44.9 106gC-CH4 day−1), (ii) one century of future landscape change associated with the thaw-lake cycle only slightly alter CO2 and CH4 exchange, while (iii) moderate increases in thermokarst pits would strengthen both CO2uptake (−166.9 106gC-CO2 day−1) and CH4 flux (2.8 106gC-CH4 day−1) with geomorphic change from

  9. Polygonal tundra geomorphological change in response to warming alters future CO2 and CH4 flux on the Barrow Peninsula.

    Science.gov (United States)

    Lara, Mark J; McGuire, A David; Euskirchen, Eugenie S; Tweedie, Craig E; Hinkel, Kenneth M; Skurikhin, Alexei N; Romanovsky, Vladimir E; Grosse, Guido; Bolton, W Robert; Genet, Helene

    2015-04-01

    The landscape of the Barrow Peninsula in northern Alaska is thought to have formed over centuries to millennia, and is now dominated by ice-wedge polygonal tundra that spans drained thaw-lake basins and interstitial tundra. In nearby tundra regions, studies have identified a rapid increase in thermokarst formation (i.e., pits) over recent decades in response to climate warming, facilitating changes in polygonal tundra geomorphology. We assessed the future impact of 100 years of tundra geomorphic change on peak growing season carbon exchange in response to: (i) landscape succession associated with the thaw-lake cycle; and (ii) low, moderate, and extreme scenarios of thermokarst pit formation (10%, 30%, and 50%) reported for Alaskan arctic tundra sites. We developed a 30 × 30 m resolution tundra geomorphology map (overall accuracy:75%; Kappa:0.69) for our ~1800 km² study area composed of ten classes; drained slope, high center polygon, flat-center polygon, low center polygon, coalescent low center polygon, polygon trough, meadow, ponds, rivers, and lakes, to determine their spatial distribution across the Barrow Peninsula. Land-atmosphere CO2 and CH4 flux data were collected for the summers of 2006-2010 at eighty-two sites near Barrow, across the mapped classes. The developed geomorphic map was used for the regional assessment of carbon flux. Results indicate (i) at present during peak growing season on the Barrow Peninsula, CO2 uptake occurs at -902.3 10(6) gC-CO2 day(-1) (uncertainty using 95% CI is between -438.3 and -1366 10(6) gC-CO2 day(-1)) and CH4 flux at 28.9 10(6) gC-CH4 day(-1) (uncertainty using 95% CI is between 12.9 and 44.9 10(6) gC-CH4 day(-1)), (ii) one century of future landscape change associated with the thaw-lake cycle only slightly alter CO2 and CH4 exchange, while (iii) moderate increases in thermokarst pits would strengthen both CO2 uptake (-166.9 10(6) gC-CO2 day(-1)) and CH4 flux (2.8 10(6) gC-CH4 day(-1)) with geomorphic change from low

  10. Planting geometry as a pre-screening technique for identifying CO2 responsive rice genotypes: a case study of panicle number.

    Science.gov (United States)

    Shimono, Hiroyuki; Ozaki, Youhei; Jagadish, Krishna S V; Sakai, Hidemitsu; Usui, Yasuhiro; Hasegawa, Toshihiro; Kumagai, Etsushi; Nakano, Hiroshi; Yoshinaga, Satoshi

    2014-11-01

    Identifying CO(2) responsive genotypes is a major target for enhancing crop productivity under future global elevated atmospheric CO(2) concentration ([CO(2)]). However, [CO(2)]-fumigation facilities are extremely expensive and are not easily accessible, and are limited in space for large-scale screening. Hence, reliable donors for initiating [CO(2)]-responsive breeding programs are not in place for crops, including rice. We propose a simple and novel phenotyping method for identifying [CO(2)]-responsive genotypes, and quantify the responsiveness to low planting density over 4-year trials across both temperate and tropical conditions. Panicle number per plant is the key determinant of grain yield and hence was the focus trait across all our trials. In temperate climate, a 3-season field screening using 127 diverse rice genotypes and employing two planting densities (normal and low density) was conducted. Two japonica genotypes were selected based on their higher responsiveness to low planting density as candidates for validating the proposed phenotyping protocol as a pre-screen for [CO(2)]-responsiveness. The approach using the two selected candidates and three standard genotypes was confirmed using a free-air CO(2) enrichment facility and temperature gradient chambers under elevated [CO(2)]. In tropical climate, we grew three rice cultivars, previously identified for their [CO(2)]-responsiveness, at two planting densities. The experiments provided confirmation that responsiveness to low planting density was correlated with that of [CO(2)]-responsiveness across both the temperate and tropical conditions. The planting density would be useful pre-screening method for testing large panels of diverse germplasm at low cost complemented by available CO(2) -control facilities for final validation of candidates from the pre-screens. © 2014 Scandinavian Plant Physiology Society.

  11. Response of photosynthesis in the leaves of cucumber seedlings to light intensity and CO2 concentration under nitrate stress

    OpenAIRE

    Yang, Xiaoyu; Wang, Xiufeng; Wei, Min

    2014-01-01

    The effects of 2 nitrate levels, 14 (CK) and 140 mmol L-1 (T), on the leaf gas exchange variables of cucumber (Cucumis sativus L. cv. Xintaimici) seedlings grown in hydroponic culture were investigated. Photosynthetic light- and CO2-response curves from CK and T seedlings were determined and used for the analysis of photosynthetic capacity. The results showed that nitrate stress resulted in a significant reduction of net photosynthesis of T seedlings compared with CK. At the same time, the ap...

  12. Responses of Gmelina arborea, a tropical deciduous tree species, to elevated atmospheric CO2: growth, biomass productivity and carbon sequestration efficacy.

    Science.gov (United States)

    Rasineni, Girish K; Guha, Anirban; Reddy, Attipalli R

    2011-10-01

    The photosynthetic response of trees to rising CO(2) concentrations largely depends on source-sink relations, in addition to differences in responsiveness by species, genotype, and functional group. Previous studies on elevated CO(2) responses in trees have either doubled the gas concentration (>700 μmol mol(-1)) or used single large addition of CO(2) (500-600 μmol mol(-1)). In this study, Gmelina arborea, a fast growing tropical deciduous tree species, was selected to determine the photosynthetic efficiency, growth response and overall source-sink relations under near elevated atmospheric CO(2) concentration (460 μmol mol(-1)). Net photosynthetic rate of Gmelina was ~30% higher in plants grown in elevated CO(2) compared with ambient CO(2)-grown plants. The elevated CO(2) concentration also had significant effect on photochemical and biochemical capacities evidenced by changes in F(V)/F(M), ABS/CSm, ET(0)/CSm and RuBPcase activity. The study also revealed that elevated CO(2) conditions significantly increased absolute growth rate, above ground biomass and carbon sequestration potential in Gmelina which sequestered ~2100 g tree(-1) carbon after 120 days of treatment when compared to ambient CO(2)-grown plants. Our data indicate that young Gmelina could accumulate significant biomass and escape acclimatory down-regulation of photosynthesis due to high source-sink capacity even with an increase of 100 μmo lmol(-1) CO(2). Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  13. Drought responses of two gymnosperm species with contrasting stomatal regulation strategies under elevated [CO2] and temperature.

    Science.gov (United States)

    Duan, Honglang; O'Grady, Anthony P; Duursma, Remko A; Choat, Brendan; Huang, Guomin; Smith, Renee A; Jiang, Yanan; Tissue, David T

    2015-07-01

    Future climate regimes characterized by rising [CO2], rising temperatures and associated droughts may differentially affect tree growth and physiology. However, the interactive effects of these three factors are complex because elevated [CO2] and elevated temperature may generate differential physiological responses during drought. To date, the interactive effects of elevated [CO2] and elevated temperature on drought-induced tree mortality remain poorly understood in gymnosperm species that differ in stomatal regulation strategies. Water relations and carbon dynamics were examined in two species with contrasting stomatal regulation strategies: Pinus radiata D. Don (relatively isohydric gymnosperm; regulating stomata to maintain leaf water potential above critical thresholds) and Callitris rhomboidea R. Br (relatively anisohydric gymnosperm; allowing leaf water potential to decline as the soil dries), to assess response to drought as a function of [CO2] and temperature. Both species were grown in two [CO2] (C(a) (ambient, 400 μl l(-1)) and C(e) (elevated, 640 μl l(-1))) and two temperature (T(a) (ambient) and T(e) (ambient +4 °C)) treatments in a sun-lit glasshouse under well-watered conditions. Drought plants were then exposed to a progressive drought until mortality. Prior to mortality, extensive xylem cavitation occurred in both species, but significant depletion of non-structural carbohydrates was not observed in either species. Te resulted in faster mortality in P. radiata, but it did not modify the time-to-mortality in C. rhomboidea. C(e) did not delay the time-to-mortality in either species under drought or T(e) treatments. In summary, elevated temperature (+4 °C) had greater influence than elevated [CO2] (+240 μl l(-1)) on drought responses of the two studied gymnosperm species, while stomatal regulation strategies did not generally affect the relative contributions of hydraulic failure and carbohydrate depletion to mortality under severe drought.

  14. Exercise training effects on hypoxic and hypercapnic ventilatory responses in mice selected for increased voluntary wheel running.

    Science.gov (United States)

    Kelly, Scott A; Rezende, Enrico L; Chappell, Mark A; Gomes, Fernando R; Kolb, Erik M; Malisch, Jessica L; Rhodes, Justin S; Mitchell, Gordon S; Garland, Theodore

    2014-02-01

    What is the central question of this study? We used experimental evolution to determine how selective breeding for high voluntary wheel running and exercise training (7-11 weeks) affect ventilatory chemoreflexes of laboratory mice at rest. What is the main finding and its importance? Selective breeding, although significantly affecting some traits, did not systematically alter ventilation across gas concentrations. As with most human studies, our findings support the idea that endurance training attenuates resting ventilation. However, little evidence was found for a correlation between ventilatory chemoreflexes and the amount of individual voluntary wheel running. We conclude that exercise 'training' alters respiratory behaviours, but these changes may not be necessary to achieve high levels of wheel running. Ventilatory control is affected by genetics, the environment and gene-environment and gene-gene interactions. Here, we used an experimental evolution approach to test whether 37 generations of selective breeding for high voluntary wheel running (genetic effects) and/or long-term (7-11 weeks) wheel access (training effects) alter acute respiratory behaviour of mice resting in normoxic, hypoxic and hypercapnic conditions. As the four replicate high-runner (HR) lines run much more than the four non-selected control (C) lines, we also examined whether the amount of exercise among individual mice was a quantitative predictor of ventilatory chemoreflexes at rest. Selective breeding and/or wheel access significantly affected several traits. In normoxia, HR mice tended to have lower mass-adjusted rates of oxygen consumption and carbon dioxide production. Chronic wheel access increased oxygen consumption and carbon dioxide production in both HR and C mice during hypercapnia. Breathing frequency and minute ventilation were significantly reduced by chronic wheel access in both HR and C mice during hypoxia. Selection history, while significantly affecting some traits

  15. Finlay-Wilkinson's regression coefficient as a pre-screening criterion for yield responsiveness to elevated atmospheric CO2 concentration in crops.

    Science.gov (United States)

    Kumagai, Etsushi; Homma, Koki; Kuroda, Eiki; Shimono, Hiroyuki

    2016-11-01

    The rising atmospheric CO2 concentration ([CO2 ]) can increase crop productivity, but there are likely to be intraspecific variations in the response. To meet future world food demand, screening for genotypes with high [CO2 ] responsiveness will be a useful option, but there is no criterion for high [CO2 ] responsiveness. We hypothesized that the Finlay-Wilkinson regression coefficient (RC) (for the relationship between a genotype's yield versus the mean yield of all genotypes in a specific environment) could serve as a pre-screening criterion for identifying genotypes that respond strongly to elevated [CO2 ]. We collected datasets on the yield of 6 rice and 10 soybean genotypes along environmental gradients and compared their responsiveness to elevated [CO2 ] based on the regression coefficients (i.e. the increases of yield per 100 µmol mol(-1) [CO2 ]) identified in previous reports. We found significant positive correlations between the RCs and the responsiveness of yield to elevated [CO2 ] in both rice and soybean. This result raises the possibility that the coefficient of the Finlay-Wilkinson relationship could be used as a pre-screening criterion for [CO2 ] responsiveness. © 2016 Scandinavian Plant Physiology Society.

  16. Guard cell sensory systems: recent insights on stomatal responses to light, abscisic acid, and CO2.

    Science.gov (United States)

    Assmann, Sarah M; Jegla, Timothy

    2016-10-01

    By controlling the opening and closure of the stomatal pores through which gas exchange occurs, guard cells regulate two of the most important plant physiological processes: photosynthesis and transpiration. Accordingly, guard cells have evolved exquisite sensory systems. Here we summarize recent literature on guard cell sensing of light, drought (via the phytohormone abscisic acid (ABA)), and CO2. New advances in our understanding of how guard cells satisfy the energetic and osmotic requirements of stomatal opening and utilize phosphorylation to regulate the anion channels and aquaporins involved in ABA-stimulated stomatal closure are highlighted. Omics and modeling approaches are providing new information that will ultimately allow an integrated understanding of guard cell physiology. Copyright © 2016. Published by Elsevier Ltd.

  17. Evaluating the responses of forest ecosystems to climate change and CO2 using dynamic global vegetation models.

    Science.gov (United States)

    Song, Xiang; Zeng, Xiaodong

    2017-02-01

    The climate has important influences on the distribution and structure of forest ecosystems, which may lead to vital feedback to climate change. However, much of the existing work focuses on the changes in carbon fluxes or water cycles due to climate change and/or atmospheric CO 2, and few studies have considered how and to what extent climate change and CO 2 influence the ecosystem structure (e.g., fractional coverage change) and the changes in the responses of ecosystems with different characteristics. In this work, two dynamic global vegetation models (DGVMs): IAP-DGVM coupled with CLM3 and CLM4-CNDV, were used to investigate the response of the forest ecosystem structure to changes in climate (temperature and precipitation) and CO 2 concentration. In the temperature sensitivity tests, warming reduced the global area-averaged ecosystem gross primary production in the two models, which decreased global forest area. Furthermore, the changes in tree fractional coverage (ΔFtree; %) from the two models were sensitive to the regional temperature and ecosystem structure, i.e., the mean annual temperature (MAT; °C) largely determined whether ΔFtree was positive or negative, while the tree fractional coverage (Ftree; %) played a decisive role in the amplitude of ΔFtree around the globe, and the dependence was more remarkable in IAP-DGVM. In cases with precipitation change, Ftree had a uniformly positive relationship with precipitation, especially in the transition zones of forests (30% < Ftree < 60%) for IAP-DGVM and in semiarid and arid regions for CLM4-CNDV. Moreover, ΔFtree had a stronger dependence on Ftree than on the mean annual precipitation (MAP; mm/year). It was also demonstrated that both models captured the fertilization effects of the CO 2 concentration.

  18. Changes in fungal community composition in response to elevated atmospheric CO2 and nitrogen fertilization varies with soil horizon

    Directory of Open Access Journals (Sweden)

    Carolyn F Weber

    2013-04-01

    Full Text Available Increasing levels of atmospheric carbon dioxide (CO2 and rates of nitrogen (N-deposition to forest ecosystems are predicted to alter the structure and function of soil fungal communities, but the spatially heterogeneous distribution of soil fungi has hampered investigations aimed at understanding such impacts. We hypothesized that soil physical and chemical properties and fungal community composition would be differentially impacted by elevated atmospheric CO2 (eCO2 and N-fertilization in spatially separated field samples, in the forest floor, 0-2 cm, 2-5 cm and 5-10 cm depth intervals in a loblolly pine Free-Air-Carbon Dioxide Enrichment (FACE experiment. In all soils, quantitative PCR-based estimates of fungal biomass were highest in the forest floor. Fungal richness, based on pyrosequencing of the fungal ribosomal large subunit gene, increased in response to N-fertilization in 0-2 cm and forest floor intervals. Composition shifted in forest floor, 0-2 cm and 2-5 cm intervals in response to N-fertilization, but the shift was most distinct in the 0-2 cm interval, in which the largest number of statistically significant changes in soil chemical parameters (i.e phosphorus, organic matter, calcium, pH was also observed. In the 0-2 cm interval, increased recovery of sequences from the Thelephoraceae, Tricholomataceae, Hypocreaceae, Clavicipitaceae, and Herpotrichiellaceae families and decreased recovery of sequences from the Amanitaceae correlated with N-fertilization. In this same depth interval, Amanitaceae, Tricholomataceae and Herpotriciellaceae sequences were recovered less frequently from soils exposed to eCO2 relative to ambient conditions. These results demonstrated that vertical stratification should be taken into consideration in future efforts to elucidate environmental impacts on fungal communities and their feedbacks on ecosystem processes.

  19. Carbon and oxygen isotope analysis of leaf biomass reveals contrasting photosynthetic responses to elevated CO2 near geologic vents in Yellowstone National Park

    Directory of Open Access Journals (Sweden)

    D. G. Williams

    2009-01-01

    Full Text Available In this study we explore the use of natural CO2 emissions in Yellowstone National Park (YNP in Wyoming, USA to study responses of natural vegetation to elevated CO2 levels. Radiocarbon (14C analysis of leaf biomass from a conifer (Pinus contortus; lodgepole pine and an invasive, non-native herb (Linaria dalmatica; Dalmation toadflax was used to trace the inputs of vent CO2 and quantify assimilation-weighted CO2 concentrations experienced by individual plants near vents and in comparable locations with no geologic CO2 exposure. The carbon and oxygen isotopic composition and nitrogen percent of leaf biomass from the same plants was used to investigate photosynthetic responses of these plants to naturally elevated atmospheric CO2 concentrations. The coupled shifts in carbon and oxygen isotope values suggest that dalmation toadflax responded to elevated CO2 exposure by increasing stomatal conductance with no change in photosynthetic capacity and lodgepole pine apparently responded by decreasing stomatal conductance and photosynthetic capacity. Lodgepole pine saplings exposed to elevated levels of CO2 likewise had reduced leaf nitrogen concentrations compared to plants with no enhanced CO2 exposure, further suggesting widespread and dominant conifer down-regulated photosynthetic capacity under elevated CO2 levels near geologic vents.

  20. Rapid response of leaf photosynthesis in two fern species Pteridium aquilinum and Thelypteris dentata to changes in CO2 measured by tunable diode laser absorption spectroscopy.

    Science.gov (United States)

    Nishida, Keisuke; Kodama, Naomi; Yonemura, Seiichiro; Hanba, Yuko T

    2015-09-01

    We investigated stomatal conductance (g(s)) and mesophyll conductance (g(m)) in response to atmospheric CO2 concentration [CO2] in two primitive land plants, the fern species Pteridium aquilinum and Thelypteris dentata, using the concurrent measurement of leaf gas exchange and carbon isotope discrimination. [CO2] was initially decreased from 400 to 200 μmol mol(-1), and then increased from 200 to 700 μmol mol(-1), and finally decreased from 700 to 400 μmol mol(-1). Analysis by tunable diode laser absorption spectroscopy (TDLAS) revealed a rapid and continuous response in g m within a few minutes. In most cases, both ferns showed rapid and significant responses of g m to changes in [CO2]. The largest changes (quote % decrease) were obtained when [CO2] was decreased from 400 to 200 μmol mol(-1). This is in contrast to angiosperms where an increase in g(m) is commonly observed at low [CO2]. Similarly, fern species observed little or no response of g(s) to changes in [CO2] whereas, a concomitant decline of g(m) and g(s) with [CO2] is often reported in angiosperms. Together, these results suggest that regulation of g(m) to [CO2] may differ between angiosperms and ferns.

  1. Effects of CO2 enrichment on the photosynthetic light response of sun and shade leaves of canopy sweetgum (Liquidambar styraciflua) in a forest ecosystem.

    Science.gov (United States)

    Herrick; Thomas

    1999-10-01

    To investigate whether sun and shade leaves respond differently to CO2 enrichment, we examined photosynthetic light response of sun and shade leaves in canopy sweetgum (Liquidambar styraciflua L.) trees growing at ambient and elevated (ambient + 200 microliters per liter) atmospheric CO2 in the Brookhaven National Laboratory/Duke University Free Air CO2 Enrichment (FACE) experiment. The sweetgum trees were naturally established in a 15-year-old forest dominated by loblolly pine (Pinus taeda L.). Measurements were made in early June and late August 1997 during the first full year of CO2 fumigation in the Duke Forest FACE experiment. Sun leaves had a 68% greater leaf mass per unit area, 63% more leaf N per unit leaf area, 27% more chlorophyll per unit leaf area and 77% greater light-saturated photosynthetic rates than shade leaves. Elevated CO2 strongly stimulated light-saturated photosynthetic rates of sun and shade leaves in June and August; however, the relative photosynthetic enhancement by elevated CO2 for sun leaves was more than double the relative enhancement of shade leaves. Elevated CO2 stimulated apparent quantum yield by 30%, but there was no interaction between CO2 and leaf position. Daytime leaf-level carbon gain extrapolated from photosynthetic light response curves indicated that sun leaves were enhanced 98% by elevated CO2, whereas shade leaves were enhanced 41%. Elevated CO2 did not significantly affect leaf N per unit area in sun or shade leaves during either measurement period. Thus, the greater CO2 enhancement of light-saturated photosynthesis in sun leaves than in shade leaves was probably a result of a greater amount of nitrogen per unit leaf area in sun leaves. A full understanding of the effects of increasing atmospheric CO2 concentrations on forest ecosystems must take account of the complex nature of the light environment through the canopy and how light interacts with CO2 to affect photosynthesis.

  2. Mixed effects of elevated pCO2 on fertilisation, larval and juvenile development and adult responses in the mobile subtidal scallop Mimachlamys asperrima (Lamarck, 1819).

    Science.gov (United States)

    Scanes, Elliot; Parker, Laura M; O'Connor, Wayne A; Ross, Pauline M

    2014-01-01

    Ocean acidification is predicted to have severe consequences for calcifying marine organisms especially molluscs. Recent studies, however, have found that molluscs in marine environments with naturally elevated or fluctuating CO2 or with an active, high metabolic rate lifestyle may have a capacity to acclimate and be resilient to exposures of elevated environmental pCO2. The aim of this study was to determine the effects of near future concentrations of elevated pCO2 on the larval and adult stages of the mobile doughboy scallop, Mimachlamys asperrima from a subtidal and stable physio-chemical environment. It was found that fertilisation and the shell length of early larval stages of M. asperrima decreased as pCO2 increased, however, there were less pronounced effects of elevated pCO2 on the shell length of later larval stages, with high pCO2 enhancing growth in some instances. Byssal attachment and condition index of adult M. asperrima decreased with elevated pCO2, while in contrast there was no effect on standard metabolic rate or pHe. The responses of larval and adult M. asperrima to elevated pCO2 measured in this study were more moderate than responses previously reported for intertidal oysters and mussels. Even this more moderate set of responses are still likely to reduce the abundance of M. asperrima and potentially other scallop species in the world's oceans at predicted future pCO2 levels.

  3. EXPERIMENTAL DESIGN AND RESPONSE SURFACE MODELING OF PI/PES-ZEOLITE 4A MIXED MATRIX MEMBRANE FOR CO2 SEPARATION

    Directory of Open Access Journals (Sweden)

    T. D. KUSWORO

    2015-09-01

    Full Text Available This paper investigates the effect of preparation of polyimide/polyethersulfone (PI/PES blending-zeolite mixed matrix membrane through the manipulation of membrane production variables such as polymer concentration, blending composition and zeolite loading. Combination of central composite design and response surface methodology were applied to determine the main effect and interaction effects of these variables on membrane separation performance. The quadratic models between each response and the independent parameters were developed and the response surface models were tested with analysis of variance (ANOVA. In this study, PI/ (PES–zeolite 4A mixed matrix membranes were casted using dry/wet phase inversion technique. The separation performance of mixed matrix membrane had been tested using pure gases such as CO2 and CH4. The results showed that zeolite loading was the most significant variable that influenced the CO2/CH4 selectivity among three variables and the experimental results were in good agreement with those predicted by the proposed regression models. The gas separation performance of the membrane was relatively higher as compare to polymeric membrane. Therefore, combination of central composite design and response surface methodology can be used to prepare optimal condition for mixed matrix membrane fabrication. The incorporation of 20 wt% zeolite 4A into 25 wt% of PI/PES matrix had resulted in a high separation performance of membrane material.

  4. Outsourcing CO2 Emissions

    Science.gov (United States)

    Davis, S. J.; Caldeira, K. G.

    2009-12-01

    CO2 emissions from the burning of fossil fuels are the primary cause of global warming. Much attention has been focused on the CO2 directly emitted by each country, but relatively little attention has been paid to the amount of emissions associated with consumption of goods and services in each country. This consumption-based emissions inventory differs from the production-based inventory because of imports and exports of goods and services that, either directly or indirectly, involved CO2 emissions. Using the latest available data and reasonable assumptions regarding trans-shipment of embodied carbon through third-party countries, we developed a global consumption-based CO2 emissions inventory and have calculated associated consumption-based energy and carbon intensities. We find that, in 2004, 24% of CO2 emissions are effectively outsourced to other countries, with much of the developed world outsourcing CO2 emissions to emerging markets, principally China. Some wealthy countries, including Switzerland and Sweden, outsource over half of their consumption-based emissions, with many northern Europeans outsourcing more than three tons of emissions per person per year. The United States is both a big importer and exporter of emissions embodied in trade, outsourcing >2.6 tons of CO2 per person and at the same time as >2.0 tons of CO2 per person are outsourced to the United States. These large flows indicate that CO2 emissions embodied in trade must be taken into consideration when considering responsibility for increasing atmospheric greenhouse gas concentrations.

  5. Xylem anatomical responses of Vaccinium myrtillus exposed to air CO2 enrichment and soil warming at treeline

    Science.gov (United States)

    Anadon-Rosell, Alba; Fonti, Patrick; Dawes, Melissa; von Arx, Georg

    2016-04-01

    Plant life at treeline is limited by harsh growth conditions. In this study we used nine years of free air CO2 enrichment (+200 ppm from 2001 to 2009) and six years of soil warming (+4 °C from 2007 to 2012) at a treeline experimental site in the Swiss Alps to investigate xylem anatomical responses of Vaccinium myrtillus, a co-dominant dwarf shrub in many treeline communities. Our aim was to identify whether the release from limiting growth conditions induced adjustments of the water conductive and storage tissues. High-resolution images of wood anatomical microsections from the stem base of 40 individuals were captured with a digital camera mounted on a microscope. We used the specialized image analysis tool ROXAS to quantify size, density, grouping patterns, and potential hydraulic conductivity of vessels. In addition, we measured the abundance and distribution of ray parenchyma. Our preliminary results show that CO2 enrichment and soil warming induced contrasting anatomical responses. In the last years of the CO2 enhancement vessels were larger, whereas soil warming induced an immediate reduction of vessel size. Moreover, larger vessels were found when V. myrtillus was in cohabitation with pine as opposed to larch. Results for ray parenchyma measurements did not show clear trends, although warming seemed to have a slightly positive effect on the fraction of uniseriate vs. multiseriate rays. These results suggest that release from the growth limiting factors can result in contrasting and partially lagged responses in the hydraulic system with little impact on the storage tissues. In addition, the overstory species seem to play a key role on the anatomy of V. myrtillus at treeline.

  6. Modeled responses of terrestrial ecosystems to elevated atmospheric CO2: a comparison of simulations by the biogeochemistry models of the Vegetation/Ecosystem Modeling and Analysis Project (VEMAP).

    Science.gov (United States)

    Pan, Yude; Melillo, Jerry M; McGuire, A David; Kicklighter, David W; Pitelka, Louis F; Hibbard, Kathy; Pierce, Lars L; Running, Steven W; Ojima, Dennis S; Parton, William J; Schimel, David S

    1998-04-01

    Although there is a great deal of information concerning responses to increases in atmospheric CO2 at the tissue and plant levels, there are substantially fewer studies that have investigated ecosystem-level responses in the context of integrated carbon, water, and nutrient cycles. Because our understanding of ecosystem responses to elevated CO2 is incomplete, modeling is a tool that can be used to investigate the role of plant and soil interactions in the response of terrestrial ecosystems to elevated CO2. In this study, we analyze the responses of net primary production (NPP) to doubled CO2 from 355 to 710 ppmv among three biogeochemistry models in the Vegetation/Ecosystem Modeling and Analysis Project (VEMAP): BIOME-BGC (BioGeochemical Cycles), Century, and the Terrestrial Ecosystem Model (TEM). For the conterminous United States, doubled atmospheric CO2 causes NPP to increase by 5% in Century, 8% in TEM, and 11% in BIOME-BGC. Multiple regression analyses between the NPP response to doubled CO2 and the mean annual temperature and annual precipitation of biomes or grid cells indicate that there are negative relationships between precipitation and the response of NPP to doubled CO2 for all three models. In contrast, there are different relationships between temperature and the response of NPP to doubled CO2 for the three models: there is a negative relationship in the responses of BIOME-BGC, no relationship in the responses of Century, and a positive relationship in the responses of TEM. In BIOME-BGC, the NPP response to doubled CO2 is controlled by the change in transpiration associated with reduced leaf conductance to water vapor. This change affects soil water, then leaf area development and, finally, NPP. In Century, the response of NPP to doubled CO2 is controlled by changes in decomposition rates associated with increased soil moisture that results from reduced evapotranspiration. This change affects nitrogen availability for plants, which influences NPP. In

  7. Invasive submerged freshwater macrophytes are more plastic in their response to light intensity than to the availability of free CO2 in air-equilibrated water

    DEFF Research Database (Denmark)

    Eller, Franziska; Alnoee, Anette B.; Boderskov, Teis

    2015-01-01

    1. The future increase in the atmospheric CO2 concentration is likely to affect the growth and performance of submerged freshwater macrophytes because of higher concentrations of free CO2 in the water at air equilibrium. We measured the plastic responses to free CO2 and light for several traits...... of four invasive aquatic plants (Elodea canadensis, Egeria densa, Hydrilla verticillata and Ceratophyllum demersum) that use bicarbonate. 2. The plants were grown in standard culture media at either high (HiC, c. 50 lmol L 1) or low concentrations of free CO2 (LowC, c. 19 lmol L 1) combined with high (Hi...

  8. Forward modeling of 4D seismic response to the CO2 injection at the Ketzin pilot site with the reflectivity method

    OpenAIRE

    Alexandra Ivanova; Monika Ivandic; Thomas Kempka; M. Diersch [Gil; P. Bergmann; S. Lueth

    2014-01-01

    When CO2 replaces brine as a free gas it is well known to affect the elastic properties of porous media considerably. 3D seismic time-lapse surveys (4D seismics) have proven to be a suitable technique for monitoring of injected CO2. Forward modeling of a 4D seismic response to the CO2 fluid substitution in a storage reservoir is an important step in such studies. In order to track the migration of CO2 at the Ketzin pilot site (Germany), 3D time-lapse seismic data were acquired by means of ...

  9. Evaluation of terrestrial carbon cycle models for their response to climate variability and to CO2 trends.

    Science.gov (United States)

    Piao, Shilong; Sitch, Stephen; Ciais, Philippe; Friedlingstein, Pierre; Peylin, Philippe; Wang, Xuhui; Ahlström, Anders; Anav, Alessandro; Canadell, Josep G; Cong, Nan; Huntingford, Chris; Jung, Martin; Levis, Sam; Levy, Peter E; Li, Junsheng; Lin, Xin; Lomas, Mark R; Lu, Meng; Luo, Yiqi; Ma, Yuecun; Myneni, Ranga B; Poulter, Ben; Sun, Zhenzhong; Wang, Tao; Viovy, Nicolas; Zaehle, Soenke; Zeng, Ning

    2013-07-01

    The purpose of this study was to evaluate 10 process-based terrestrial biosphere models that were used for the IPCC fifth Assessment Report. The simulated gross primary productivity (GPP) is compared with flux-tower-based estimates by Jung et al. [Journal of Geophysical Research 116 (2011) G00J07] (JU11). The net primary productivity (NPP) apparent sensitivity to climate variability and atmospheric CO2 trends is diagnosed from each model output, using statistical functions. The temperature sensitivity is compared against ecosystem field warming experiments results. The CO2 sensitivity of NPP is compared to the results from four Free-Air CO2 Enrichment (FACE) experiments. The simulated global net biome productivity (NBP) is compared with the residual land sink (RLS) of the global carbon budget from Friedlingstein et al. [Nature Geoscience 3 (2010) 811] (FR10). We found that models produce a higher GPP (133 ± 15 Pg C yr(-1) ) than JU11 (118 ± 6 Pg C yr(-1) ). In response to rising atmospheric CO2 concentration, modeled NPP increases on average by 16% (5-20%) per 100 ppm, a slightly larger apparent sensitivity of NPP to CO2 than that measured at the FACE experiment locations (13% per 100 ppm). Global NBP differs markedly among individual models, although the mean value of 2.0 ± 0.8 Pg C yr(-1) is remarkably close to the mean value of RLS (2.1 ± 1.2 Pg C yr(-1) ). The interannual variability in modeled NBP is significantly correlated with that of RLS for the period 1980-2009. Both model-to-model and interannual variation in model GPP is larger than that in model NBP due to the strong coupling causing a positive correlation between ecosystem respiration and GPP in the model. The average linear regression slope of global NBP vs. temperature across the 10 models is -3.0 ± 1.5 Pg C yr(-1) °C(-1) , within the uncertainty of what derived from RLS (-3.9 ± 1.1 Pg C yr(-1) °C(-1) ). However, 9 of 10 models overestimate the regression slope of NBP vs. precipitation

  10. Dynamic Response of Southwest Juniper to Shifting Climate and Natural and Anthropogenic Changes in Atmospheric pCO2

    Science.gov (United States)

    Zinniker, D. A.; Holmgren, C. A.; Pagani, M.

    2008-12-01

    Fossil packrat middens in the southwestern US contribute critical details to our understanding of past climate change and floral migrations across geography and elevation. Our presentation discusses the development of a largely unexplored molecular organic archive preserved in packrat middens from the southwestern US: the stable isotopic analysis of diet-averaged taxon specific biomarkers in both modern middens from southern Arizona and New Mexico and ancient middens from the Peloncillo Mountains of SE Arizona. The stable carbon isotope values of taxon specific makers allow estimations of changing growing season intra-leaf CO2 concentrations, carbon assimilation rates, and water use efficiency. Hydrogen isotope values aid in estimating growing season relative humidity. This more specifically reflects the extent of dry season transpiration and associated deuterium enrichment and can be seen as a simplified proxy for growing season phenology in perennial desert shrubs and trees. For southwest juniper, the derived isotopic record of phenology and growth indicates a remarkable sensitivity to changes in hydrology, temperature, and pCO2. Juniper growth rates are interpreted to have increased 70% from the Last Glacial Maximum to Holocene in response to CO2 fertilization. However, a decrease in deuterium enrichment during the Bølling Allerod and Holocene indicates that elevated temperatures and limited access to soil moisture considerably shortened juniper growing seasons during these periods. Low midden preservation rates and rare juniper macrofossils in the Early and Mid Holocene provide additional evidence of overall drying and the seasonality of shallow groundwater during these periods. Increasing midden occurrence, juniper macrofossils, and deuterium enrichment in the Late Holocene suggest that afforestation during this time period was associated with lengthening juniper growing seasons. Carbon isotopic shifts between pre-industrial and modern middens suggest a 30

  11. Simple additive effects are rare: a quantitative review of plant biomass and soil process responses to combined manipulations of CO2 and temperature

    DEFF Research Database (Denmark)

    Dieleman, Wouter I.J.; Vicca, Sara; Dijkstra, Feike A.

    2012-01-01

    In recent years, increased awareness of the potential interactions between rising atmospheric CO2 concentrations ([ CO2 ]) and temperature has illustrated the importance of multifactorial ecosystem manipulation experiments for validating Earth System models. To address the urgent need for increased...... understanding of responses in multifactorial experiments, this article synthesizes how ecosystem productivity and soil processes respond to combined warming and [ CO2 ] manipulation, and compares it with those obtained in single factor [ CO2 ] and temperature manipulation experiments. Across all combined...... and the [ CO2 ]-only treatments elicited larger stimulation of fine root biomass than of aboveground biomass, consistently stimulated soil respiration, and decreased foliar nitrogen (N) concentration. Nonetheless, mineral N availability declined less in the combined treatment than in the [ CO2 ]-only treatment...

  12. Simple additive effects are rare: a quantitative review of plant biomass and soil process responses to combined manipulations of CO2 and temperature

    DEFF Research Database (Denmark)

    Dieleman, Wouter I. J.; Vicca, Sara; Dijkstra, Feike A.

    2012-01-01

    In recent years, increased awareness of the potential interactions between rising atmospheric CO2 concentrations ([ CO2 ]) and temperature has illustrated the importance of multifactorial ecosystem manipulation experiments for validating Earth System models. To address the urgent need for increased...... understanding of responses in multifactorial experiments, this article synthesizes how ecosystem productivity and soil processes respond to combined warming and [ CO2 ] manipulation, and compares it with those obtained in single factor [ CO2 ] and temperature manipulation experiments. Across all combined...... and the [ CO2 ]‐only treatments elicited larger stimulation of fine root biomass than of aboveground biomass, consistently stimulated soil respiration, and decreased foliar nitrogen (N) concentration. Nonetheless, mineral N availability declined less in the combined treatment than in the [ CO2 ]‐only treatment...

  13. Boom and bust: rapid feedback responses between insect outbreak dynamics and canopy leaf area impacted by rainfall and CO2.

    Science.gov (United States)

    Gherlenda, Andrew N; Esveld, Jessica L; Hall, Aidan A G; Duursma, Remko A; Riegler, Markus

    2016-11-01

    Frequency and severity of insect outbreaks in forest ecosystems are predicted to increase with climate change. How this will impact canopy leaf area in future climates is rarely tested. Here, we document function of insect outbreaks that fortuitously and rapidly occurred in an ecosystem under free-air CO2 enrichment. Over the first 2 years of CO2 fumigation of a naturally established mature Eucalyptus woodland, we continuously assessed population responses of three sap-feeding insect species of the psyllid genera Cardiaspina, Glycaspis and Spondyliaspis for up to ten consecutive generations. Concurrently, we quantified changes in the canopy leaf area index (LAI). Large and rapid shifts in psyllid community composition were recorded between species with either flush (Glycaspis) or senescence-inducing (Cardiaspina, Spondyliaspis) feeding strategies. Within the second year, two psyllid species experienced significant and rapid population build-up resulting in two consecutive outbreaks: first, rainfall stimulated Eucalyptus leaf production increasing LAI, which supported population growth of flush-feeding Glycaspis without impacting LAI. Glycaspis numbers then crashed and were followed by the outbreak of senescence-feeding Cardiaspina fiscella that led to significant defoliation and reduction in LAI. For all three psyllid species, the abundance of lerps, protective coverings excreted by the sessile nymphs, decreased at e[CO2 ]. Higher lerp weight at e[CO2 ] for Glycaspis but not the other psyllid species provided evidence for compensatory feeding by the flush feeder but not the two senescence feeders. Our study demonstrates that rainfall drives leaf phenology, facilitating the rapid boom-and-bust succession of psyllid species, eventually leading to significant defoliation due to the second but not the first outbreaking psyllid species. In contrast, e[CO2 ] may impact psyllid abundance and feeding behaviour, with psyllid species-specific outcomes for defoliation

  14. Dinuclear Rhenium Complex with a Proton Responsive Ligand as a Redox Catalyst for the Electrochemical CO2 Reduction.

    Science.gov (United States)

    Wilting, Alexander; Stolper, Thorsten; Mata, Ricardo A; Siewert, Inke

    2017-04-03

    Herein, we present the reduction chemistry of a dinuclear α-diimine rhenium complex, 1, [Re2(L)(CO)6Cl2], with a proton responsive ligand and its application as a catalyst in the electrochemical CO2 reduction reaction (L = 4-tert-butyl-2,6-bis(6-(1H-imidazol-2-yl)-pyridin-2-yl)phenol). The complex has a phenol group in close proximity to the active center, which may act as a proton relay during catalysis, and pyridine-NH-imidazole units as α-diimine donors. The complex is an active catalyst for the electrochemical CO2 reduction reaction. CO is the main product after catalysis, and only small amounts of H2 were observed, which can be related to the ligand reactivity. The ic/ip ratio of 20 in dimethylformamide (DMF) + 10% water for 1 points to a higher activity with regard to [Re(bpy)(CO)3Cl] in MeCN/H2O, albeit 1 requires a slightly larger overpotential (bpy = 2,2'-bipyridine). Spectroscopic and theoretical investigations revealed detailed information about the reduction chemistry of 1. The complex exhibits two reduction processes in DMF, and each process was identified as a two-electron reduction in the absence of CO2. The first 2e- reduction is ligand based and leads to homolytic N-H bond cleavage reactions at the imidazole units of 1, which is equal to a net double proton removal from 1 forming [Re2(LH-2)(CO)6Cl2]2-. The second 2e- reduction process has been identified as an O-H bond cleavage reaction at the phenol group, removal of chloride ions from the coordination spheres of the metal ions, and a ligand-centered one-electron reduction of [Re2(LH-3)(CO)6Cl]2-. In the presence of CO2, the second reduction process initiates catalysis. The reduced species is highly nucleophilic and likely favors the reaction with CO2 instead of O-H bond cleavage.

  15. Response of carbon assimilation and chlorophyll fluorescence to soybean leaf phosphorus across CO2: Alternative electron sink, nutrient efficiency and critical phosphorus concentration

    Science.gov (United States)

    To evaluate the response of CO2 assimilation (PN) and various chlorophyll fluorescence (CF) parameters to phosphorus (P) nutrition soybean plants were grown in controlled environment growth chambers with sufficient (0.50 mM) and deficient (0.10 and 0.01 mM) P supply under ambient and elevated CO2 (a...

  16. Nitrate fertilisation does not enhance CO2 responses in two tropical seagrass species

    National Research Council Canada - National Science Library

    Ow, Y X; Vogel, N; Collier, C J; Holtum, J A M; Flores, F; Uthicke, S

    2016-01-01

    Seagrasses are often considered "winners" of ocean acidification (OA); however, seagrass productivity responses to OA could be limited by nitrogen availability, since nitrogen-derived metabolites are required for carbon assimilation...

  17. Detection of elevated CO2 responsive QTLs for yield and its ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-06-03

    . Accepted 12 May, 2008. A mapping population of IR24 (indica) chromosome segment substitution lines (CSSLs.) in Asominori. (japonica) background was used to detect quantitative trait loci (QTLs) for response to elevated ...

  18. Assessment of the brain’s macro- and microcirculatory blood flow responses to CO2 via transfer function analysis

    Directory of Open Access Journals (Sweden)

    Martin WOlf-DIetrich Müller

    2016-05-01

    Full Text Available Objectives: At present, there is no standard bedside method for assessing cerebral autoregulation (CA with high temporal resolution. We combined the two methods most commonly used for this purpose, transcranial Doppler sonography (TCD, macrocirculation level and near-infrared spectroscopy (NIRS, microcirculation level, in an attempt to identify the most promising approach. Methods: In 8 healthy subjects (5 women; mean age, 38 ± 10 years, CA disturbance was achieved by adding carbon dioxide (CO2 to the breathing air. We simultaneously recorded end-tidal CO2 (ETCO2, blood pressure (BP; non-invasively at the fingertip, and cerebral blood flow velocity (CBFV in both middle cerebral arteries using TCD and determined oxygenated and deoxygenated hemoglobin levels using NIRS. For the analysis, we used transfer function calculations in the low-frequency band (0.07–0.15 Hz to compare BP–CBFV, BP–oxygenated hemoglobin (OxHb, BP–tissue oxygenation index (TOI, CBFV–OxHb, and CBFV–TOI.Results: ETCO2 increased from 37 ± 2 to 44 ± 3 mmHg. The CO2-induced CBFV increase significantly correlated with the OxHb increase (R2 = 0.526, p < 0.001. Compared with baseline, the mean CO2 administration phase shift (in radians significantly increased (p < 0.005 from -0.67 ± 0.20 to -0.51 ± 0.25 in the BP–CBFV system, and decreased from 1.21 ± 0.81 to −0.05 ± 0.91 in the CBFV–OxHb system, and from 0.94 ± 1.22 to −0.24 ± 1.0 in the CBFV–TOI system; no change was observed for BP–OxHb (0.38 ± 1.17 to 0.41 ± 1.42. Gain changed significantly only in the BP–CBFV system. The correlation between the ETCO2 change and phase change was higher in the CBFV–OxHb system [r = −0.60; 95% confidence interval (CI, −0.16, −0.84; p < 0.01] than in the BP–CBFV system (r = 0.52; 95% CI: 0.03, 0.08; p < 0.05.Conclusion: The transfer function characterizes the blood flow transition from macro- to microcirculation by time delay only. The CBFV

  19. Microbial Priming and Protected Carbon Responses to Elevated CO2 at Local to Global Scales: a New Modeling Approach

    Science.gov (United States)

    Sulman, B. N.; Oishi, C.; Shevliakova, E.; Pacala, S. W.

    2013-12-01

    The soil carbon formulations commonly used in global carbon cycle models and Earth System models (ESMs) are based on first-order decomposition equations, where turnover of carbon is determined only by the size of the carbon pool and empirical functions of responses to temperature and moisture. These models do not include microbial dynamics or protection of carbon in microaggregates and mineral complexes, making them incapable of simulating important soil processes like priming and the influence of soil physical structure on carbon turnover. We present a new soil carbon dynamics model - Carbon, Organisms, Respiration, and Protection in the Soil Environment (CORPSE) - that explicitly represents microbial biomass and protected carbon pools. The model includes multiple types of carbon with different chemically determined turnover rates that interact with a single dynamic microbial biomass pool, allowing the model to simulate priming effects. The model also includes the formation and turnover of protected carbon that is inaccessible to microbial decomposers. The rate of protected carbon formation increases with microbial biomass. CORPSE has been implemented both as a stand-alone model and as a component of the NOAA Geophysical Fluid Dynamics Laboratory (GFDL) ESM. We calibrated the model against measured soil carbon stocks from the Duke FACE experiment. The model successfully simulated the seasonal pattern of heterotrophic CO2 production. We investigated the roles of priming and protection in soil carbon accumulation by running the model using measured inputs of leaf litter, fine roots, and root exudates from the ambient and elevated CO2 plots at the Duke FACE experiment. Measurements from the experiment showed that elevated CO2 caused enhanced root exudation, increasing soil carbon turnover in the rhizosphere due to priming effects. We tested the impact of increased root exudation on soil carbon accumulation by comparing model simulations of carbon accumulation under

  20. Role of nitric oxide-containing factors in the ventilatory and cardiovascular responses elicited by hypoxic challenge in isoflurane-anesthetized rats.

    Science.gov (United States)

    Mendoza, James P; Passafaro, Rachael J; Baby, Santhosh M; Young, Alex P; Bates, James N; Gaston, Benjamin; Lewis, Stephen J

    2014-06-01

    Exposure to hypoxia elicits changes in mean arterial blood pressure (MAP), heart rate, and frequency of breathing (fR). The objective of this study was to determine the role of nitric oxide (NO) in the cardiovascular and ventilatory responses elicited by brief exposures to hypoxia in isoflurane-anesthetized rats. The rats were instrumented to record MAP, heart rate, and fR and then exposed to 90 s episodes of hypoxia (10% O2, 90% N2) before and after injection of vehicle, the NO synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME), or the inactive enantiomer D-NAME (both at 50 μmol/kg iv). Each episode of hypoxia elicited a decrease in MAP, bidirectional changes in heart rate (initial increase and then a decrease), and an increase in fR. These responses were similar before and after injection of vehicle or D-NAME. In contrast, the hypoxia-induced decreases in MAP were attenuated after administration of L-NAME. The initial increases in heart rate during hypoxia were amplified whereas the subsequent decreases in heart rate were attenuated in L-NAME-treated rats. Finally, the hypoxia-induced increases in fR were virtually identical before and after administration of L-NAME. These findings suggest that NO factors play a vital role in the expression of the cardiovascular but not the ventilatory responses elicited by brief episodes of hypoxia in isoflurane-anesthetized rats. Based on existing evidence that NO factors play a vital role in carotid body and central responses to hypoxia in conscious rats, our findings raise the novel possibility that isoflurane blunts this NO-dependent signaling. Copyright © 2014 the American Physiological Society.

  1. Response of detritus food web and litter quality to elevated CO2 and crop cultivars and their feedback to soil functionality

    Science.gov (United States)

    Hu, Zhengkun; Chen, Xiaoyun; Zhu, Chunwu; Bonkowski, Michael; Hu, Shuijin; Li, Huixin; Hu, Feng; Liu, Manqiang

    2017-04-01

    Elevated atmospheric CO2 concentrations (eCO2) often increase plant growth and alter the belowground detritus soil food web. Interactions with agriculture management may further modify soil process and the associated ecosystem functionality. Little attention, however, has been directed toward assessing the responses of soil food web and their feedback to soil functionality, particularly in wetland agroecosystems. We report results from a long-term free air CO2 enrichment (FACE) experiment in a rice paddy field that examined the responses of detritus food webs to eCO2 (200 ppm higher than ambient CO2 (aCO2)) of two rice cultivars with distinctly weak and strong responses to eCO2. Soil detritus food web components, including soil microbes and microfauna, soil environment as well as resources availability variables, were determined at the rice ripening stage. To obtain the information of soil functionality, indicated by litter decomposition and enzyme activities, we adopted a reciprocal transplant approach that fully manipulate the factors of litter straw and food web components for the incubation of 120 days. Results about the field investigation showed that eCO2 lead to a higher C/N ratio of litter and soil compared to aCO2, especially for the strong responsive cultivar. eCO2-induced enhanced carbon input stimulated the fungal decomposition pathway by increasing fungal biomass, fungi: bacteria ratio and fungivorous nematode. Results from the manipulative incubation experiment showed eCO2-induced lower quality of straw decreased cumulative C mineralization, but changes in detritus food web induced by eCO2 and strongly responsive cultivar lead to an increased CO2 respiration coincidently within each straw type, mainly due to the adaption to the high C/N ratio environment which increased their functional breadth. Based on SEMs and curves of carbon mineralization rate, soil communities showed significant effects on C release at the early stage through mediating enzyme

  2. Carbon Dioxide Production Responsibility on the Basis of comparing in Situ and mean CO2 Atmosphere Concentration Data

    OpenAIRE

    Mavrodiev, S. Cht.; Pekevski, L.; Vachev, B.

    2008-01-01

    The method is proposed for estimation of regional CO2 and other greenhouses and pollutants production responcibility. The comparison of CO2 local emissions reduction data with world CO2 atmosphere data will permit easy to judge for overall effect in curbing not only global warming but also chemical polution.

  3. Parameters optimization of supercritical fluid-CO2 extracts of frankincense using response surface methodology and its pharmacodynamics effects.

    Science.gov (United States)

    Zhou, Jing; Ma, Xing-miao; Qiu, Bi-Han; Chen, Jun-xia; Bian, Lin; Pan, Lin-mei

    2013-01-01

    The volatile oil parts of frankincense (Boswellia carterii Birdw.) were extracted with supercritical carbon dioxide under constant pressure (15, 20, or 25 MPa) and fixed temperature (40, 50, or 60°C), given time (60, 90, or 120 min) aiming at the acquisition of enriched fractions containing octyl acetate, compounds of pharmaceutical interest. A mathematical model was created by Box-Behnken design, a popular template for response surface methodology, for the extraction process. The response value was characterized by synthetical score, which comprised yields accounting for 20% and content of octyl acetate for 80%. The content of octyl acetate was determined by GC. The supercritical fluid extraction showed higher selectivity than conventional steam distillation. Supercritical fluid-CO(2) for extracting frankincense under optimum condition was of great validity, which was also successfully verified by the pharmacological experiments. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. THE RESPONSE OF PLANT CARBOHYDRATES TO ELEVATED CO2: WHAT HAVE WE LEARNT FROM FACE STUDIES?

    Energy Technology Data Exchange (ETDEWEB)

    ROGERS,A.; AINSWORTH,E.A.; BERNACCHI,C.J.; GIBON,Y.; STITT,M.; LONG,S.P.

    2004-08-29

    Atmospheric CO{sub 2} concentration ([CO{sub 2}]) is expected to rise from a current level of 372 {micro}mol mol{sup -1} to about 550 {micro}mol mol{sup -1} by the middle of the century (Prentice 2001). Accumulation of foliar carbohydrates is one of the most pronounced and universal changes observed in the leaves of C{sub 3} plants grown at elevated [CO{sub 2}] (Drake et al 1997). Carbohydrates are the product of photosynthetic cells and the substrate for sink metabolism. However, carbohydrates are not just substrates, changes in the composition and pool size of foliar carbohydrates have the potential to communicate source-sink balance and a role for carbohydrates in the regulation of the expression of many plant genes is well established (Koch 1996). Importantly, carbohydrate feedback is thought to be the mechanism through which long-term exposure to elevated [CO{sub 2}] leads to a reduction in carboxylation capacity (Rogers et a1 199S, Long et al 2004). Foliar sugar content has recently been linked to an increased susceptibility of soybeans to insect herbivory (Hamilton et al submitted). In addition increases in the C:N ratio of leaf litter of plants grown at elevated [CO{sub 2}] has been implicated in negative feedbacks on ecosystem productivity (Oechel et al 1994). Understanding of the response of foliar carbohydrates will form an important part of our ability to understand and predict the effects of rising [CO{sub 2}] on plants and ecosystems. As Free-Air CO{sub 2} enrichment technology was emerging, understanding of the link between carbohydrates and plant responses to rising [CO{sub 2}] was increasing. However, there were concerns that the hypotheses generated using model system or from studies on mostly juvenile plants grown for relatively short periods of time in controlled environments may not translate to the field. Of particular concern was the effect of a limited rooting volume. Arp (1991) argued that photosynthetic acclimation to elevated [CO{sub 2

  5. The retrotrapezoid nucleus neurons expressing Atoh1 and Phox2b are essential for the respiratory response to CO2

    Science.gov (United States)

    Ruffault, Pierre-Louis; D'Autréaux, Fabien; Hayes, John A; Nomaksteinsky, Marc; Autran, Sandra; Fujiyama, Tomoyuki; Hoshino, Mikio; Hägglund, Martin; Kiehn, Ole; Brunet, Jean-François; Fortin, Gilles; Goridis, Christo

    2015-01-01

    Maintaining constant CO2 and H+ concentrations in the arterial blood is critical for life. The principal mechanism through which this is achieved in mammals is the respiratory chemoreflex whose circuitry is still elusive. A candidate element of this circuitry is the retrotrapezoid nucleus (RTN), a collection of neurons at the ventral medullary surface that are activated by increased CO2 or low pH and project to the respiratory rhythm generator. Here, we use intersectional genetic strategies to lesion the RTN neurons defined by Atoh1 and Phox2b expression and to block or activate their synaptic output. Photostimulation of these neurons entrains the respiratory rhythm. Conversely, abrogating expression of Atoh1 or Phox2b or glutamatergic transmission in these cells curtails the phrenic nerve response to low pH in embryonic preparations and abolishes the respiratory chemoreflex in behaving animals. Thus, the RTN neurons expressing Atoh1 and Phox2b are a necessary component of the chemoreflex circuitry. DOI: http://dx.doi.org/10.7554/eLife.07051.001 PMID:25866925

  6. Effect of stellate ganglion block on hemodynamics and stress responses during CO2-pneumoperitoneum in elderly patients.

    Science.gov (United States)

    Chen, Yong-Quan; Xie, Yu-Yizi; Wang, Bin; Jin, Xiao-Ju

    2017-02-01

    Elderly patients undergoing elective laparoscopic cholecystectomy (LC) were given right stellate ganglion block (RSGB) to observe its effects on the hemodynamics and stress response during carbon dioxide (CO2)-pneumoperitoneum. A randomized, single-blinded, and placebo-controlled study. University-affiliated teaching hospital. Sixty patients (aged 65-78years; weight, 45-75kg; American Society of Anesthesiologists (ASA) physical status classification, class I or II) undergoing elective LC. Right stellate ganglion block was performed via C7 access using 10mL of 1% lidocaine in all patients. The patients' heart rate (HR) and mean arterial pressure (MAP) were recorded before the block (T0), 5min following pneumoperitoneum (T1), 30min following pneumoperitoneum (T2), 5min following the deflation of pneumoperitoneum (T3), and upon completion of the surgery (T4). Additionally, the concentrations of epinephrine (E), norepinephrine (NE) and cortisol (COR) were detected in arterial blood at each time point by enzyme-linked immunosorbent assay. For control group, the MAP and RPP (RPP=SBP×HR) were significantly elevated at T1~3 (Pblock can reduce blood catecholamines during CO2-pneumoperitoneum to maintain perioperative hemodynamic stability and prevent adverse cardiovascular events in elderly patients. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. Adaptation response surfaces for managing wheat under perturbed climate and CO2 in a Mediterranean environment

    DEFF Research Database (Denmark)

    Ruiz-Ramos, M.; Ferrise, Roberto; Rodríguez, A

    2018-01-01

    Adaptation of crops to climate change has to be addressed locally due to the variability of soil, climate and the specific socio-economic settings influencing farm management decisions. Adaptation of rainfed cropping systems in the Mediterranean is especially challenging due to the projected......, a combination of adaptations for dealing with climate change demonstrated that effective adaptation is possible at Lleida. Combinations based on a cultivar without vernalization requirements showed good and wide adaptation potential. Few combined adaptation options performed well under rainfed conditions...... decline in precipitation in the coming decades, which will increase the risk of droughts. Methods that can help explore uncertainties in climate projections and crop modelling, such as impact response surfaces (IRSs) and ensemble modelling, can then be valuable for identifying effective adaptations. Here...

  8. The metabolic response of pteropods to acidification reflects natural CO2-exposure in oxygen minimum zones

    Directory of Open Access Journals (Sweden)

    K. F. Wishner

    2012-02-01

    Full Text Available Shelled pteropods (Thecosomata are a group of holoplanktonic mollusks that are believed to be especially sensitive to ocean acidification because their aragonitic shells are highly soluble. Despite this concern, there is very little known about the physiological response of these animals to conditions of elevated carbon dioxide. This study examines the oxygen consumption and ammonia excretion of five pteropod species, collected from tropical regions of the Pacific Ocean, to elevated levels of carbon dioxide (0.10%, 1000 ppm. Our results show that pteropods that naturally migrate into oxygen minimum zones, such as Hyalocylis striata, Clio pyramidata, Cavolinia longirostris and Creseis virgula, were not affected by carbon dioxide at the levels and duration tested. Diacria quadridentata, which does not migrate, responds to high carbon dioxide conditions with reduced oxygen consumption and ammonia excretion. This indicates that the natural chemical environment of individual species may influence their resilience to ocean acidification.

  9. Responses to atmospheric CO2 concentrations in crop simulation models: a review of current simple and semicomplex representations and options for model development.

    Science.gov (United States)

    Vanuytrecht, Eline; Thorburn, Peter J

    2017-05-01

    Elevated atmospheric CO2 concentrations ([CO2 ]) cause direct changes in crop physiological processes (e.g. photosynthesis and stomatal conductance). To represent these CO2 responses, commonly used crop simulation models have been amended, using simple and semicomplex representations of the processes involved. Yet, there is no standard approach to and often poor documentation of these developments. This study used a bottom-up approach (starting with the APSIM framework as case study) to evaluate modelled responses in a consortium of commonly used crop models and illuminate whether variation in responses reflects true uncertainty in our understanding compared to arbitrary choices of model developers. Diversity in simulated CO2 responses and limited validation were common among models, both within the APSIM framework and more generally. Whereas production responses show some consistency up to moderately high [CO2 ] (around 700 ppm), transpiration and stomatal responses vary more widely in nature and magnitude (e.g. a decrease in stomatal conductance varying between 35% and 90% among models was found for [CO2 ] doubling to 700 ppm). Most notably, nitrogen responses were found to be included in few crop models despite being commonly observed and critical for the simulation of photosynthetic acclimation, crop nutritional quality and carbon allocation. We suggest harmonization and consideration of more mechanistic concepts in particular subroutines, for example, for the simulation of N dynamics, as a way to improve our predictive understanding of CO2 responses and capture secondary processes. Intercomparison studies could assist in this aim, provided that they go beyond simple output comparison and explicitly identify the representations and assumptions that are causal for intermodel differences. Additionally, validation and proper documentation of the representation of CO2 responses within models should be prioritized. © 2017 John Wiley & Sons Ltd.

  10. The growth response of Alternanthera philoxeroides in a simulated post-combustion emission with ultrahigh [CO2] and acidic pollutants.

    Science.gov (United States)

    Xu, Cheng-Yuan; Griffin, Kevin L; Blazier, John C; Craig, Elizabeth C; Gilbert, Dominique S; Sritrairat, Sanpisa; Anderson, O Roger; Castaldi, Marco J; Beaumont, Larry

    2009-07-01

    Although post-combustion emissions from power plants are a major source of air pollution, they contain excess CO2 that could be used to fertilize commercial greenhouses and stimulate plant growth. We addressed the combined effects of ultrahigh [CO2] and acidic pollutants in flue gas on the growth of Alternanthera philoxeroides. When acidic pollutants were excluded, the biomass yield of A. philoxeroides saturated near 2000 micromol mol(-1) [CO2] with doubled biomass accumulation relative to the ambient control. The growth enhancement was maintained at 5000 micromol mol(-1) [CO2], but declined when [CO2] rose above 1%, in association with a strong photosynthetic inhibition. Although acidic components (SO2 and NO2) significantly offset the CO2 enhancement, the aboveground yield increased considerably when the concentration of pollutants was moderate (200 times dilution). Our results indicate that using excess CO2 from the power plant emissions to optimize growth in commercial green house could be viable.

  11. Loss of Homeostatic Gas Exchange in Eastern Hemlock in Response to Pollution and Rising CO2?

    Science.gov (United States)

    Rayback, S. A.; Gagen, M. H.; Lini, A.; Cogbill, C. V.

    2014-12-01

    In eastern North American, multiple environmental effects, natural and anthropogenic, may impinge upon tree-ring based stable carbon isotope ratios when examined over long time periods. Investigation of relationships between a Vermont (USA) eastern hemlock δ¹³C (1849-2010) chronology and local and regional climate variables, as well as a regional sulfur dioxide time series revealed the decoupling of δ¹³C from significant climate drivers such as May-August maximum temperature (r=0.50, pwater use efficiency (iWUE) showed homeostatic maintenance of ci levels against ca until 1965 and rising iWUE. Then, ci increased proportional (1965-2000) and later at the same rate as ca (2001-2010) and iWUE leveled off indicating a potential loss of sensitivity to increasing atmospheric carbon dioxide. This more recent passive response may be an indication of a loss of homeostatic maintenance of stomatal control and/or may be linked to changing climate in the region (e.g., wetter conditions).

  12. Stomatal response to humidity and CO2 implicated in recent decline in US evaporation.

    Science.gov (United States)

    Rigden, Angela J; Salvucci, Guido D

    2017-03-01

    Evapotranspiration, defined as the total flux of water from the land surface to the atmosphere, is a major component of the hydrologic cycle and surface energy balance. Although evapotranspiration is expected to intensify with increasing temperatures, long-term, regional trends in evapotranspiration remain uncertain due to spatially and temporally limited direct measurements. In this study, we utilize an emergent relation between the land surface and atmospheric boundary layer to infer daily evapotranspiration from historical meteorological data collected at 236 weather stations across the United States. Our results suggest a statistically significant (α = 0.05) decrease in evapotranspiration of approximately 6% from 1961 to 2014, with a significant (α = 0.05) sharp decline of 13% from 1998 to 2014. We attribute the decrease in evapotranspiration mostly to declines in surface conductance, but also to offsetting changes in longwave radiation, wind speed, and incoming solar radiation. Using an established stomatal conductance model, we explain the changes in inferred surface conductance as a response to increases in carbon dioxide and, more recently, to an abrupt decrease in atmospheric humidity. © 2016 John Wiley & Sons Ltd.

  13. Radiative forcing and temperature response to changes in urban albedos and associated CO2 offsets

    Energy Technology Data Exchange (ETDEWEB)

    Menon, Surabi; Akbari, Hashem; Mahanama, Sarith; Sednev, Igor; Levinson, Ronnen

    2010-02-12

    The two main forcings that can counteract to some extent the positive forcings from greenhouse gases from pre-industrial times to present-day are the aerosol and related aerosol-cloud forcings, and the radiative response to changes in surface albedo. Here, we quantify the change in radiative forcing and land surface temperature that may be obtained by increasing the albedos of roofs and pavements in urban areas in temperate and tropical regions of the globe by 0.1. Using the catchment land surface model (the land model coupled to the GEOS-5 Atmospheric General Circulation Model), we quantify the change in the total outgoing (outgoing shortwave+longwave) radiation and land surface temperature to a 0.1 increase in urban albedos for all global land areas. The global average increase in the total outgoing radiation was 0.5 Wm{sup -2}, and temperature decreased by {approx}0.008 K for an average 0.003 increase in surface albedo. These averages represent all global land areas where data were available from the land surface model used and are for the boreal summer (June-July-August). For the continental U.S. the total outgoing radiation increased by 2.3 Wm{sup -2}, and land surface temperature decreased by {approx}0.03 K for an average 0.01 increase in surface albedo. Based on these forcings, the expected emitted CO{sub 2} offset for a plausible 0.25 and 0.15 increase in albedos of roofs and pavements, respectively, for all global urban areas, was found to be {approx} 57 Gt CO{sub 2}. A more meaningful evaluation of the impacts of urban albedo increases on global climate and the expected CO{sub 2} offsets would require simulations which better characterizes urban surfaces and represents the full annual cycle.

  14. PHOTOSYNTHESIS AND RESOURCE ALLOCATION OF THREE MOJAVE DESERT GRASSES IN RESPONSE TO ELEVATED ATMOSPHERIC CO2

    Energy Technology Data Exchange (ETDEWEB)

    L. A. DEFALCO; C. K. IVANS; P. VIVIN; J. R. SEEMANN; R. S. NOWAK

    2004-01-01

    Gas exchange, biomass and N allocation were compared among three Mojave Desert grasses representing different functional types to determine if photosynthetic responses and the associated allocation of resources within the plant changed after prolonged exposure to elevated CO{sub 2}. Leaf gas exchange characteristics were measured for Bromus madritensis ssp. rubens (C{sub 3} invasive annual), Achnatherum hymenoides (C{sub 3} native perennial) and Pleuraphis rigida (C{sub 4} native perennial) exposed to 360 {micro}mol mol{sup -1} (ambient) and 1000 {micro}mol mol{sup -1} (elevated) CO{sub 2} concentrations in a glasshouse experiment, and tissue biomass and total N pools were quantified from three harvests during development. The maximum rate of carboxylation by the N-rich enzyme Rubisco (Vc{sub max}), which was inferred from the relationship between net CO{sub 2} assimilation (A{sub net}) and intracellular CO{sub 2} concentration (c{sub i}), declined in the C{sub 3} species Bromus and Achnatherum across all sampling dates, but did not change at elevated CO{sub 2} for the C{sub 4} Pleuraphis. Whole plant N remained the same between CO{sub 2} treatments for all species, but patterns of allocation differed for the short- and long-lived C{sub 3} species. For Bromus, leaf N used for photosynthesis was reallocated to reproduction at elevated CO{sub 2} as inferred from the combination of lower Vc{sub max} and N per leaf area (NLA) at elevated CO{sub 2}, but similar specific leaf area (SLA, cm{sup 2} g{sup -1}), and of greater reproductive effort (RE) for the elevated CO{sub 2} treatment. Vc{sub max}, leaf N concentration and NLA declined for the perennial Achnatherum at elevated CO{sub 2} potentially due to accumulation of carbohydrates or changes in leaf morphology inferred from lower SLA and greater total biomass at elevated CO{sub 2}. In contrast, Vc{sub max} for the C{sub 4} perennial Pleuraphis did not change at elevated CO{sub 2}, and tissue biomass and total N were

  15. Can current moisture responses predict soil CO2 efflux under altered precipitation regimes? A synthesis of manipulation experiments

    DEFF Research Database (Denmark)

    Vicca, S.; Bahn, M.; Estiarte, M.

    2014-01-01

    As a key component of the carbon cycle, soil CO2 efflux (SCE) is being increasingly studied to improve our mechanistic understanding of this important carbon flux. Predicting ecosystem responses to climate change often depends on extrapolation of current relationships between ecosystem processes...... to fluctuations in soil temperature and soil water content can be used to predict SCE under altered rainfall patterns. Of the 58 experiments for which we gathered SCE data, 20 were discarded because either too few data were available or inconsistencies precluded their incorporation in the analyses. The 38...... remaining experiments were used to test the hypothesis that a model parameterized with data from the control plots (using soil temperature and water content as predictor variables) could adequately predict SCE measured in the manipulated treatment. Only for 7 of these 38 experiments was this hypothesis...

  16. Endogenous Opioids and Ventilatory Adaptation to Prolonged Hypoxia in Goats,

    Science.gov (United States)

    1984-06-25

    the rise in arterial PCO 2 with .- gA. IV. 10 long-term acclimatization in goats and attributed it to. augmented production of CO2 by the rumen of the...proposed that, with prolonged hypoxia, partial non-respiratory compensation for metabolic acidosis in the central nervous system acts to decrease ventilatory

  17. Effects of Elevated [CO2] and Low Soil Moisture on the Physiological Responses of Mountain Maple (Acer spicatum L.) Seedlings to Light

    OpenAIRE

    Gabriel Danyagri; Qing-Lai Dang

    2013-01-01

    Global climate change is expected to affect how plants respond to their physical and biological environments. In this study, we examined the effects of elevated CO2 ([CO2]) and low soil moisture on the physiological responses of mountain maple (Acer spicatum L.) seedlings to light availability. The seedlings were grown at ambient (392 µmol mol(-1)) and elevated (784 µmol mol(-1)) [CO2], low and high soil moisture (M) regimes, at high light (100%) and low light (30%) in the greenhouse for one ...

  18. Microbial association with the dynamics of particulate organic carbon in response to the amendment of elevated CO2-derived wheat residue into a Mollisol.

    Science.gov (United States)

    Wang, Yanhong; Yu, Zhenhua; Li, Yansheng; Wang, Guanghua; Liu, Junjie; Liu, Judong; Liu, Xiaobing; Jin, Jian

    2017-12-31

    As the chemical quality of crop residue is likely to be affected by elevated CO2 (eCO2), residue amendments may influence soil organic carbon (SOC) sequestration. However, in Mollisols, the dynamics of the SOC fractions in response to amendment with wheat residue produced under eCO2 and the corresponding microbial community composition remain unknown. Such investigation is essential to residue management, which affects the soil quality and productivity of future farming systems. To narrow this knowledge gap, (13)C-labeled shoot and root residue derived from ambient CO2 (aCO2) or eCO2 were amended into Mollisols and incubated for 200days. The soil was sampled during the incubation period to determine the residue-C retained in the three SOC fractions, i.e., coarse intra-aggregate particulate organic C (coarse iPOC), fine iPOC and mineral-associated organic C (MOC). The soil bacterial community was assessed using a MiSeq sequencing instrument. The results showed that the increase in SOC concentrations attributable to the application of the wheat residue primarily occurred in the coarse iPOC fraction. Compared with the aCO2-derived shoot residue, the amendment of eCO2-derived shoot residue resulted in greater SOC concentrations, whereas no significant differences (P>0.05) were observed between the aCO2- and eCO2-derived roots. Principal coordinates analysis (PCoA) showed that the residue amendment significantly (P≤0.05) altered the bacterial community composition compared with the non-residue amendment. Additionally, the bacterial community in the aCO2-derived shoot treatment differed from those in the other residue treatments until day 200 of the incubation period. The eCO2-derived shoot treatment significantly increased (P≤0.05) the relative abundances of the genera Acidobacteriaceae_(Subgroup_1)_uncultured, Bryobacter, Candidatus_Solibacter, Gemmatimonas and Nitrosomonadaceae_uncultured, whereas the opposite trend was observed in Nonomuraea, Actinomadura

  19. Response to multi-generational selection under elevated [CO2] in two temperature regimes suggests enhanced carbon assimilation and increased reproductive output in Brassica napus L.

    Science.gov (United States)

    Frenck, Georg; van der Linden, Leon; Mikkelsen, Teis Nørgaard; Brix, Hans; Jørgensen, Rikke Bagger

    2013-01-01

    Functional plant traits are likely to adapt under the sustained pressure imposed by environmental changes through natural selection. Employing Brassica napus as a model, a multi-generational study was performed to investigate the potential trajectories of selection at elevated [CO2] in two different temperature regimes. To reveal phenotypic divergence at the manipulated [CO2] and temperature conditions, a full-factorial natural selection regime was established in a phytotron environment over the range of four generations. It is demonstrated that a directional response to selection at elevated [CO2] led to higher quantities of reproductive output over the range of investigated generations independent of the applied temperature regime. The increase in seed yield caused an increase in aboveground biomass. This suggests quantitative changes in the functions of carbon sequestration of plants subjected to increased levels of CO2 over the generational range investigated. The results of this study suggest that phenotypic divergence of plants selected under elevated atmospheric CO2 concentration may drive the future functions of plant productivity to be different from projections that do not incorporate selection responses of plants. This study accentuates the importance of phenotypic responses across multiple generations in relation to our understanding of biogeochemical dynamics of future ecosystems. Furthermore, the positive selection response of reproductive output under increased [CO2] may ameliorate depressions in plant reproductive fitness caused by higher temperatures in situations where both factors co-occur. PMID:23762504

  20. Reversal in competitive dominance of a toxic versus non-toxic cyanobacterium in response to rising CO2

    NARCIS (Netherlands)

    Van de Waal, D.B.; Verspagen, J.M.H.; Finke, J.F; Vournazou, V.; Immers, A.; Kardinaal, W.E.A.; Tonk, L.; Becker, S.; Van Donk, E.; Visser, P.M.; Huisman, J.

    2011-01-01

    Climate change scenarios predict a doubling of the atmospheric CO2 concentration by the end of this century. Yet, how rising CO2 will affect the species composition of aquatic microbial communities is still largely an open question. In this study, we develop a resource competition model to

  1. A natural experiment on plant acclimation: lifetime stomatal frequency response of an individual tree to annual atmospheric CO2increase

    NARCIS (Netherlands)

    Wagner, F.; Below, R.; Klerk, P. de; Dilcher, D.L.; Joosten, H.; Kürschner, W.M.; Visscher, H.

    1996-01-01

    Carbon dioxide (CO2) has been increasing in atmospheric concentration since the Industrial Revolution. A decreasing number of stomata on leaves of land plants still provides the only morphological evidence that this man-made increase has already affected the biosphere. The current rate of CO2

  2. Atmospheric CO2 alters resistance of arabidopsis to Pseudomonas syringae by affecting abscisic acid accumulation and stomatal responsiveness to coronatine

    NARCIS (Netherlands)

    Zhou, Yeling; Vroegop-Vos, Irene; Schuurink, Robert C; Pieterse, Corné M.J.; Van Wees, Saskia C.M.

    2017-01-01

    Atmospheric CO2 influences plant growth and stomatal aperture. Effects of high or low CO2 levels on plant disease resistance are less well understood. Here, resistance of Arabidopsis thaliana against the foliar pathogen Pseudomonas syringae pv. tomato DC3000 (Pst) was investigated at three different

  3. Antecedent moisture and temperature conditions modulate the response of ecosystem respiration to elevated CO2 and warming

    Science.gov (United States)

    Terrestrial plant and soil respiration, or ecosystem respiration (Reco), represents a major CO2 flux in the global carbon cycle. However, there is disagreement in how Reco will respond to future global changes, such as elevated atmosphere CO2 and warming. To address this, we synthesized six years (2...

  4. Leaf photosynthetic and morphological responses to elevated CO2 concentration and altered fruit number in the semi-closed greenhouse

    NARCIS (Netherlands)

    Qian, T.; Dieleman, J.A.; Elings, A.; Marcelis, L.F.M.

    2012-01-01

    Semi-closed greenhouses have been developed to reduce the energy consumption in horticulture. In these greenhouses, CO2 concentration is higher than in the conventional modern greenhouses due to the reduction of window ventilation. Photosynthetic and morphological acclimation to elevated CO2 has

  5. Responses of soybeans and wheat to elevated CO2 in free-air and open top chamber systems

    Science.gov (United States)

    With increasing demand for agricultural products, more confidence is needed concerning impacts of rising atmospheric CO2 on crop yields. Despite debate about the merits of free-air CO2 enrichment (FACE) and open top chamber (OTC) systems, there has been only one reported experiment directly compari...

  6. High CO2 atmosphere modulating the phenolic response associated with cell adhesion and hardening of Annona cherimola fruit stored at chilling temperature.

    Science.gov (United States)

    Maldonado, Roberto; Molina-Garcia, Antonio D; Sanchez-Ballesta, Maria T; Escribano, Maria I; Merodio, Carmen

    2002-12-18

    Phenylalanine ammonia-lyase (PAL, EC 4.3.1.5.) activity, tanning ability, and polyphenols levels were measured in cherimoya (Annona cherimola Mill.) fruit treated with 20% CO(2) + 20% O(2) + 60% N(2) for 1, 3, or 6 days during chilling temperature (6 degrees C) storage. The residual effect of CO(2) after transfer to air was also studied. These observations were correlated with texture and cellular characteristics, visualized by cryo-SEM. Tanning ability and the early increase in tannin polyphenols induced by chilling temperature were reduced by CO(2) treatment. Conversely, high CO(2) atmosphere enhanced the nontannin polyphenol fraction as compared with fruit stored in air. Lignin accumulation and PAL activation observed in untreated fruit after prolonged storage at chilling temperature were prevented by high CO(2). Moreover, the restraining effect on lignification was less effective when the CO(2) treatment was prolonged for 6 days. In addition, fruits held at these conditions had greater firmness and the histological characterization of the separation between cells was similar to that in untreated fruits. We conclude that CO(2) treatment modulates the phenolic response that seems to regulate the strength of cell adhesion and so to prevent hardening caused by chilling temperature storage.

  7. Elevated CO2 decreases the response of the ethylene signaling pathway in Medicago truncatula and increases the abundance of the pea aphid.

    Science.gov (United States)

    Guo, Huijuan; Sun, Yucheng; Li, Yuefei; Liu, Xianghui; Zhang, Wenhao; Ge, Feng

    2014-01-01

    The performance of herbivorous insects is greatly affected by plant nutritional quality and resistance, which are likely to be altered by rising concentrations of atmospheric CO2 . We previously reported that elevated CO2 enhanced biological nitrogen (N) fixation of Medicago truncatula, which could result in an increased supply of amino acids to the pea aphid (Acyrthosiphon pisum). The current study examined the N nutritional quality and aphid resistance of sickle, an ethylene-insensitive mutant of M. truncatula with supernodulation, and its wild-type control A17 under elevated CO2 in open-top field chambers. Regardless of CO2 concentration, growth and amino acid content were greater and aphid resistance was lower in sickle than in A17. Elevated CO2 up-regulated N assimilation and transamination-related enzymes activities and increased phloem amino acids in both genotypes. Furthermore, elevated CO2 down-regulated expression of 1-amino-cyclopropane-carboxylic acid (ACC), sickle gene (SKL) and ethylene response transcription factors (ERF) genes in the ethylene signaling pathway of A17 when infested by aphids and decreased resistance against aphids in terms of lower activities of superoxide dismutase (SOD), peroxidase (POD), and polyphenol oxidase (PPO). Our results suggest that elevated CO2 suppresses the ethylene signaling pathway in M. truncatula, which results in an increase in plant nutritional quality for aphids and a decrease in plant resistance against aphids. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  8. Starch Content in Leaf Sheath Controlled by CO2-Responsive CCT Protein is a Potential Determinant of Photosynthetic Capacity in Rice.

    Science.gov (United States)

    Morita, Ryutaro; Inoue, Kanako; Ikeda, Ken-Ichi; Hatanaka, Tomoko; Misoo, Shuji; Fukayama, Hiroshi

    2016-11-01

    CO2-responsive CCT protein (CRCT) is the suggested positive regulator of starch synthesis in vegetative organs, particularly the leaf sheath of rice. In this study, we analyzed the effects of the starch level in the leaf sheath on the photosynthetic rate in the leaf blade using CRCT overexpression and RNA interference (RNAi) knockdown transgenic rice grown under ambient (38 Pa) or elevated (100 Pa) CO2 conditions. In leaf sheath, the starch content was markedly changed in relation to CRCT expression levels under both CO2 conditions. In contrast, the soluble sugar and starch contents of the leaf blade were markedly increased in the knockdown line grown under elevated CO2 conditions. The overexpression or RNAi knockdown of CRCT did not cause large effects on the photosynthetic rate of the transgenic lines grown under ambient CO2 condition. However, the photosynthetic rate of the overexpression line was enhanced, while that of the knockdown line was substantially decreased under elevated CO2 conditions. These photosynthetic rates were weakly correlated with the nitrogen contents and negatively correlated with the total non-structural carbohydrate contents. Thus, the capacity for starch synthesis in leaf sheath, which is controlled by CRCT, can indirectly affect the carbohydrate content, and then the photosynthetic rate in the leaf blade of rice grown under elevated CO2 conditions. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  9. Dynamics of CO2 fluxes and environmental responses in the rain-fed winter wheat ecosystem of the Loess Plateau, China.

    Science.gov (United States)

    Wang, Wen; Liao, Yuncheng; Wen, Xiaoxia; Guo, Qiang

    2013-09-01

    Chinese Loess Plateau plays an important role in carbon balance of terrestrial ecosystems. Continuous measurement of CO2 fluxes in cropland ecosystem is of great significance to accurately evaluate the carbon sequestration potential and to better explain the carbon cycle process in this region. By using the eddy covariance system we conducted a long-term (from Sep 2009 to Jun 2010) CO2 fluxes measurement in the rain-fed winter wheat field of the Chinese Loess Plateau and elaborated the responses of CO2 fluxes to environmental factors. The results show that the winter wheat ecosystem has distinct seasonal dynamics of CO2 fluxes. The total net ecosystem CO2 exchange (NEE) of -218.9±11.5 gC m(-2) in the growing season, however, after considering the harvested grain, the agro-ecosystem turned into a weak carbon sink (-36.2 gC m(-2)). On the other hand, the responses of CO2 fluxes to environmental factors depended on different growth stages of winter wheat and different ranges of environmental variables, suggesting that the variations in CO2 exchange were sensitive to the changes in controlling factors. Particularly, we found the pulse response of ecosystem respiration (Reco) to a large rainfall event, and the strong fluctuations of CO2 fluxes usually appeared after effective rainfall events (daily precipitation > 5 mm) during middle growing season. Such phenomenon also occurred in the case of the drastic changes in air temperature and within 5 days after field management (e.g. tillage and plough). Copyright © 2013 The Authors. Published by Elsevier B.V. All rights reserved.

  10. Conventional versus slug CO2 loading and the control of breathing in anaesthetized cats.

    Science.gov (United States)

    van der Grinten, C P; Schoute, E; de Vries, W R; Luijendijk, S C

    1992-01-01

    1. Conventional inspiratory CO2 loading (CCL) is accomplished by having the subject breathe CO2-enriched air. An alternative method of CO2 loading is to inject a bolus of CO2 at the start of each inspiration into the inspired air: slug CO2 loading (SCL). During SCL PCO2 in the conducting airways declines quickly towards 0 kPa in the course of inspiration, whereas PCO2 remains at a constant value equal to the inspiratory PCO2 during CCL. Therefore, CCL and SCL may stimulate the respiratory controller differently. 2. We compared the ventilatory responses to SCL and CCL in fourteen anaesthetized, spontaneously breathing cats. In each experimental animal we applied, in a fixed randomized order, five CCL experiments (fractional inspiratory CO2, FI,CO2 = 0.01-0.05), six SCL experiments (slugs of 50% CO2 ranging from 0.5 to 6 ml) and three control experiments in which no CO2 was loaded. Partial pressure of CO2 in arterial blood was determined from small blood samples (0.14 ml). In three cats we repeated the experiments after bilateral transection of the cervical vagi to evaluate the contribution of vagal receptors to the responses observed. 3. The average slope of the CO2 response curves for SCL was 2 times steeper than that for CCL (P less than 0.01). The larger minute ventilation for SCL for a particular value of arterial PCO2 (Pa,CO2) could not be attributed exclusively to the increased breathing frequency or the increased tidal volume (P greater than 0.10). Further, mean inspiratory flow (VI) was larger for SCL than for CCL at the same Pa,CO2 (P less than 0.01), also because the ratio TI/TE (inspiratory duration/expiratory duration) was smaller (P less than 0.01). After vagotomy the difference between SCL and CCL response curves was much reduced. 4. It is concluded that SCL and CCL affect the respiratory controller in a different way causing differences in breathing pattern and CO2 sensitivity between the two methods. Evidently, a mechanism based on CO2 sensitivity of

  11. Response to multi-generational selection under elevated [CO2] in two temperature regimes suggests enhanced carbon assimilation and increased reproductive output in Brassica napus L

    DEFF Research Database (Denmark)

    Frenck, Georg; van der Linden, Leon; Mikkelsen, Teis Nørgaard

    2013-01-01

    different temperature regimes. To reveal phenotypic divergence at the manipulated [CO2] and temperature conditions, a full-factorial natural selection regime was established in a phytotron environment over the range of four generations. It is demonstrated that a directional response to selection at elevated......Functional plant traits are likely to adapt under the sustained pressure imposed by environmental changes through natural selection. Employing Brassica napus as a model, a multi-generational study was performed to investigate the potential trajectories of selection at elevated [CO2] in two...... subjected to increased levels of CO2 over the generational range investigated. The results of this study suggest that phenotypic divergence of plants selected under elevated atmospheric CO2 concentration may drive the future functions of plant productivity to be different from projections that do...

  12. CO2 blood test

    Science.gov (United States)

    Bicarbonate test; HCO3-; Carbon dioxide test; TCO2; Total CO2; CO2 test - serum; Acidosis - CO2; Alkalosis - CO2 ... The CO2 test is most often done as part of an electrolyte or basic metabolic panel. Changes in your ...

  13. Expression of calcification and metabolism-related genes in response to elevated pCO2 and temperature in the reef-building coral Acropora millepora.

    Science.gov (United States)

    Rocker, Melissa M; Noonan, Sam; Humphrey, Craig; Moya, Aurelie; Willis, Bette L; Bay, Line K

    2015-12-01

    Declining health of scleractinian corals in response to deteriorating environmental conditions is widely acknowledged, however links between physiological and functional genomic responses of corals are less well understood. Here we explore growth and the expression of 20 target genes with putative roles in metabolism and calcification in the branching coral, Acropora millepora, in two separate experiments: 1) elevated pCO2 (464, 822, 1187 and 1638 μatm) and ambient temperature (27°C), and 2) elevated pCO2 (490 and 822 μatm) and temperature (28 and 31 °C). After 14 days of exposure to elevated pCO2 and ambient temperatures, no evidence of differential expression of either calcification or metabolism genes was detected between control and elevated pCO2 treatments. After 37 days of exposure to control and elevated pCO2, Ubiquinol-Cytochrome-C Reductase Subunit 2 gene (QCR2; a gene involved in complex III of the electron chain transport within the mitochondria and critical for generation of ATP) was significantly down-regulated in the elevated pCO2 treatment in both ambient and elevated temperature treatments. Overall, the general absence of a strong response to elevated pCO2 and temperature by the other 19 targeted calcification and metabolism genes suggests that corals may not be affected by these stressors on longer time scales (37 days). These results also highlight the potential for QCR2 to act as a biomarker of coral genomic responses to changing environments. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Reversal in competitive dominance of a toxic versus non-toxic cyanobacterium in response to rising CO2.

    Science.gov (United States)

    Van de Waal, Dedmer B; Verspagen, Jolanda M H; Finke, Jan F; Vournazou, Vasiliki; Immers, Anne K; Kardinaal, W Edwin A; Tonk, Linda; Becker, Sven; Van Donk, Ellen; Visser, Petra M; Huisman, Jef

    2011-09-01

    Climate change scenarios predict a doubling of the atmospheric CO(2) concentration by the end of this century. Yet, how rising CO(2) will affect the species composition of aquatic microbial communities is still largely an open question. In this study, we develop a resource competition model to investigate competition for dissolved inorganic carbon in dense algal blooms. The model predicts how dynamic changes in carbon chemistry, pH and light conditions during bloom development feed back on competing phytoplankton species. We test the model predictions in chemostat experiments with monocultures and mixtures of a toxic and non-toxic strain of the freshwater cyanobacterium Microcystis aeruginosa. The toxic strain was able to reduce dissolved CO(2) to lower concentrations than the non-toxic strain, and became dominant in competition at low CO(2) levels. Conversely, the non-toxic strain could grow at lower light levels, and became dominant in competition at high CO(2) levels but low light availability. The model captured the observed reversal in competitive dominance, and was quantitatively in good agreement with the results of the competition experiments. To assess whether microcystins might have a role in this reversal of competitive dominance, we performed further competition experiments with the wild-type strain M. aeruginosa PCC 7806 and its mcyB mutant impaired in microcystin production. The microcystin-producing wild type had a strong selective advantage at low CO(2) levels but not at high CO(2) levels. Our results thus demonstrate both in theory and experiment that rising CO(2) levels can alter the community composition and toxicity of harmful algal blooms.

  15. Lipid content and fatty acid composition of Porosira glacialis and Attheya longicornis in response to carbon dioxide (CO2 aeration.

    Directory of Open Access Journals (Sweden)

    E Y Artamonova

    Full Text Available In the current study two novel psychrophilic diatoms Porosira glacialis and Attheya longicornis were tested for suitability to CO2 mitigation coupled with production of the physiologically requisite omega- 3 fatty acids. This study is in line with the worldwide conducted research aimed at applying biorefinery concept to heavy polluting industries. Since the production of algal high value compounds, i.e. essential fatty acids, relies on utilization of residual CO2 emissions coming from industry, the costs of such production maybe substantially reduced. Besides, the ecological benefits of the biorefinery concept being implemented are obvious, since CO2 is one of the major greenhouse gases. The current research has shown that one of the tested microalgal species, the diatom P. glacialis showed good tolerance to high (20-25% levels of CO2 and maintained growth rates comparable to controls. The total lipid content in the CO2 aerated culture increased from 8.91 to 10.57% in cell dry mass. Additionally, the content of docosahexaenoic acid (DHA increased from 3.90 to 5.75%, while the concentration of eicosapentaenoic acid (EPA decreased from 26.59 to 23.66%. In contrast, A. longicornis did not demonstrate any significant increase in total lipid content. Besides, its growth was hampered by high levels of CO2 aeration.

  16. Effects of elevated [CO2] and low soil moisture on the physiological responses of Mountain Maple (Acer spicatum L. seedlings to light.

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    Gabriel Danyagri

    Full Text Available Global climate change is expected to affect how plants respond to their physical and biological environments. In this study, we examined the effects of elevated CO2 ([CO2] and low soil moisture on the physiological responses of mountain maple (Acer spicatum L. seedlings to light availability. The seedlings were grown at ambient (392 µmol mol(-1 and elevated (784 µmol mol(-1 [CO2], low and high soil moisture (M regimes, at high light (100% and low light (30% in the greenhouse for one growing season. We measured net photosynthesis (A, stomatal conductance (g s, instantaneous water use efficiency (IWUE, maximum rate of carboxylation (V cmax, rate of photosynthetic electron transport (J, triose phosphate utilization (TPU, leaf respiration (R d, light compensation point (LCP and mid-day shoot water potential (Ψx. A and g s did not show significant responses to light treatment in seedlings grown at low soil moisture treatment, but the high light significantly decreased the C i/C a in those seedlings. IWUE was significantly higher in the elevated compared with the ambient [CO2], and the effect was greater at high than the low light treatment. LCP did not respond to the soil moisture treatments when seedlings were grown in high light under both [CO2]. The low soil moisture significantly reduced Ψx but had no significant effect on the responses of other physiological traits to light or [CO2]. These results suggest that as the atmospheric [CO2] rises, the physiological performance of mountain maple seedlings in high light environments may be enhanced, particularly when soil moisture conditions are favourable.

  17. Effects of elevated [CO2] and low soil moisture on the physiological responses of Mountain Maple (Acer spicatum L.) seedlings to light.

    Science.gov (United States)

    Danyagri, Gabriel; Dang, Qing-Lai

    2013-01-01

    Global climate change is expected to affect how plants respond to their physical and biological environments. In this study, we examined the effects of elevated CO2 ([CO2]) and low soil moisture on the physiological responses of mountain maple (Acer spicatum L.) seedlings to light availability. The seedlings were grown at ambient (392 µmol mol(-1)) and elevated (784 µmol mol(-1)) [CO2], low and high soil moisture (M) regimes, at high light (100%) and low light (30%) in the greenhouse for one growing season. We measured net photosynthesis (A), stomatal conductance (g s), instantaneous water use efficiency (IWUE), maximum rate of carboxylation (V cmax), rate of photosynthetic electron transport (J), triose phosphate utilization (TPU)), leaf respiration (R d), light compensation point (LCP) and mid-day shoot water potential (Ψx). A and g s did not show significant responses to light treatment in seedlings grown at low soil moisture treatment, but the high light significantly decreased the C i/C a in those seedlings. IWUE was significantly higher in the elevated compared with the ambient [CO2], and the effect was greater at high than the low light treatment. LCP did not respond to the soil moisture treatments when seedlings were grown in high light under both [CO2]. The low soil moisture significantly reduced Ψx but had no significant effect on the responses of other physiological traits to light or [CO2]. These results suggest that as the atmospheric [CO2] rises, the physiological performance of mountain maple seedlings in high light environments may be enhanced, particularly when soil moisture conditions are favourable.

  18. Divergent responses in growth and nutritional quality of coastal macroalgae to the combination of increased pCO2 and nutrients.

    Science.gov (United States)

    Ober, Gordon T; Thornber, Carol S

    2017-10-01

    Coastal ecosystems are subjected to global and local environmental stressors, including increased atmospheric carbon dioxide (CO2) (and subsequent ocean acidification) and nutrient loading. Here, we tested how two common macroalgal species in the Northwest Atlantic (Ulva spp. and Fucus vesiculosus Linneaus) respond to the combination of increased CO2 and nutrient loading. We utilized two levels of pCO2 with two levels of nutrients in a full factorial design, testing the growth rates and tissue quality of Ulva and Fucus grown for 21 days in monoculture and biculture. We found that the opportunistic, fast-growing Ulva exhibited increased growth rates under high pCO2 and high nutrients, with growth rates increasing three-fold above Ulva grown in ambient pCO2 and ambient nutrients. By contrast, Fucus growth rates were not impacted by either environmental factor. Both species exhibited a decline in carbon to nitrogen ratios (C:N) with elevated nutrients, but pCO2 concentration did not alter tissue quality in either species. Species grown in biculture exhibited similar growth rates to those in monoculture conditions, but Fucus C:N increased significantly when grown with Ulva, indicating an effect of the presence of Ulva on Fucus. Our results suggest that the combination of ocean acidification and nutrients will enhance abundance of opportunistic algal species in coastal systems and will likely drive macroalgal community shifts, based on species-specific responses to future conditions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Jack-and-master trait responses to elevated CO2 and N: a comparison of native and introduced Phragmites australis.

    Directory of Open Access Journals (Sweden)

    Thomas J Mozdzer

    Full Text Available Global change is predicted to promote plant invasions world-wide, reducing biodiversity and ecosystem function. Phenotypic plasticity may influence the ability of introduced plant species to invade and dominate extant communities. However, interpreting differences in plasticity can be confounded by phylogenetic differences in morphology and physiology. Here we present a novel case investigating the role of fitness trait values and phenotypic plasticity to global change factors between conspecific lineages of Phragmites australis. We hypothesized that due to observed differences in the competitive success of North American-native and Eurasian-introduced P. australis genotypes, Eurasian-introduced P. australis would exhibit greater fitness in response to global change factors. Plasticity and plant performance to ambient and predicted levels of carbon dioxide and nitrogen pollution were investigated to understand how invasion pressure may change in North America under a realistic global change scenario. We found that the introduced Eurasian genotype expressed greater mean trait values in nearly every ecophysiological trait measured--aboveground and belowground--to elevated CO(2 and nitrogen, outperforming the native North American conspecific by a factor of two to three under every global change scenario. This response is consistent with "jack and master" phenotypic plasticity. We suggest that differences in plant nitrogen productivity, specific leaf area, belowground biomass allocation, and inherently higher relative growth rate are the plant traits that may enhance invasion of Eurasian Phragmites in North America. Given the high degree of genotypic variability within this species, and our limited number of genotypes, our results must be interpreted cautiously. Our study is the first to demonstrate the potential importance of jack-and-master phenotypic plasticity in plant invasions when facing imminent global change conditions. We suggest that

  20. Synergistic effect in the heterostructure of ZnCo2O4 and hydrogenated zinc oxide nanorods for high capacitive response.

    Science.gov (United States)

    Deka Boruah, Buddha; Maji, Arnab; Misra, Abha

    2017-07-13

    Herein, a novel heterostructure was fabricated by combining electrochemically and optically active materials to achieve a high capacitive response of 896 F g-1 at 5 A g-1. A network of ZnCo2O4 nanorods (NRs) was directly grown on a three-dimensional matrix of H : ZnO NRs (ZnCo2O4/H : ZnO NRs) that offered synergistic advantages by providing an optimum ion/charge transportation path, large electrochemically active surface area, and stable capacitive response during the electrolytic process. Furthermore, the fabricated solid-state asymmetric supercapacitor ZnCo2O4/H : ZnO NRs//activated carbon induced a large potential window of 1.5 V that offered excellent energy and power densities. In addition, optically active ZnCo2O4/H : ZnO NRs were also used for the conversion of optical energy over a broad wavelength range; thus, the as-fabricated asymmetric solid-state supercapacitor could easily provide the required power for the operation of a photodetector. Therefore, the unique heterostructure of ZnCo2O4/H : ZnO NRs not only presents excellent capacitive response but also demonstrates great potential for energy conversion.

  1. Interannual physiological responses of glacial trees to changes in atmospheric [CO2] since the Last Glacial Maximum

    Science.gov (United States)

    Gerhart, L. M.; Harris, J. M.; Ward, J. K.

    2009-12-01

    During the Last Glacial Maximum, atmospheric [CO2] were as low as 180 ppm and have currently risen to a modern value of 385 ppm as a result of fossil fuel combustion and deforestation. In order to understand how changing [CO2] influenced the physiology of trees over the last 50,000 years, we analyzed carbon isotope ratios of individual tree rings from juniper wood specimens from the Rancho La Brea tar pits in southern California and kauri wood specimens from peat bogs in New Zealand (North Island). Modern trees from different altitudes were compared to account for changes in precipitation and temperature through time in order to isolate the effects of changing [CO2]. We hypothesized that over the last 50,000 years, the ratio of ci (intracellular [CO2]) to ca (atmospheric [CO2]) would be maintained within each species. Consequently, ci values would be significantly lower in glacial trees due to lower ca levels during the LGM. In addition, we hypothesized that low [CO2] (which does not vary between years during the LGM) dominated tree physiology during the LGM as evidenced by low levels of inter-annual variation in ci/ca ratios relative to modern trees (which are known to respond to high frequency variation in water and temperature between years). In both kauri and juniper trees, mean ci/ca values remained constant throughout 50,000 years despite major climatic and [CO2] changes, indicating that there is a long-term physiological set point in these species. Limitations on the ci values of glacial junipers suggest that 90 ppm CO2 represents a survival compensation point for this species. In addition, glacial trees showed very low inter-annual variation in ci/ca values compared to modern trees. This suggests that glacial tree physiology may have been dominated by low CO2 that was constant between years, whereas modern trees may be dominated by climatic factors that vary substantially between years. Consequently, while each species maintained mean ci/ca values over time

  2. The response of Thalassiosira pseudonana to long-term exposure to increased CO2 and decreased pH.

    Directory of Open Access Journals (Sweden)

    Katharine J Crawfurd

    Full Text Available The effect of ocean acidification conditions has been investigated in cultures of the diatom Thalassiosira pseudonana CCMP1335. Expected end-of-the-century pCO(2 (aq concentrations of 760 µatm (equivalent to pH 7.8 were compared with present-day condition (380 µatm CO(2, pH 8.1. Batch culture pH changed rapidly because of CO(2 (aq assimilation and pH targets of 7.8 and 8.1 could not be sustained. Long-term (∼100 generation pH-auxostat, continuous cultures could be maintained at target pH when cell density was kept low (<2×10(5 cells mL(-1. After 3 months continuous culture, the C:N ratio was slightly decreased under high CO(2 conditions and red fluorescence per cell was slightly increased. However, no change was detected in photosynthetic efficiency (F(v/F(m or functional cross section of PS II (σ(PSII. Elevated pCO(2 has been predicted to be beneficial to diatoms due to reduced cost of carbon concentration mechanisms. There was reduced transcription of one putative δ-carbonic anhydrase (CA-4 after 3 months growth at increased CO(2 but 3 other δ-CAs and the small subunit of RUBISCO showed no change. There was no evidence of adaptation or clade selection of T. pseudonana after ∼100 generations at elevated CO(2. On the basis of this long-term culture, pH change of this magnitude in the future ocean may have little effect on T. pseudonana in the absence of genetic adaption.

  3. [Responses of non-structural carbohydrate metabolism of cucumber seedlings to drought stress and doubled CO2 concentration].

    Science.gov (United States)

    Dong, Yan-hong; Liu, Bin-bin; Zhang, Xu; Liu, Xue-na; Ai, Xi-zhen; Li, Qing-ming

    2015-01-01

    The effects of doubled CO2 concentration on non-structural carbohydrate metabolism of cucumber (Cucumis sativus L. cv. 'Jinyou No.1') seedlings under drought stress were investigated. Split plot design was deployed, with two levels of CO2 concentrations (ambient CO2 concentration, 380 µmol . mol-1, and doubled CO2 concentration, 760±20 µmol . mol-1) in the main plots, and three levels of water treatments (control, moderate drought stress, and severe drought stress) simulated by PEG 6000 in the split-plots. The results showed that non-structural carbohydrates of cucumber leaves, including glucose, fructose, sucrose, and stachyose, increased with the doubling of CO2 concentration, which resulted in the decreased osmotic potential, improving the drought stress in cucumber seedlings. During the drought stress, sucrose synthase, soluble acid invertase and al- kaline invertase started with an increase, and followed with a decline in the leaves. In the root system, however, soluble acid invertase and alkaline invertase increased gradually throughout the whole process, whereas sucrose phosphate synthase firstly increased and then decreased. The treatment of doubled CO2 enhanced the activity of sucrose synthase, but decreased the activity of sucrose phosphate synthase. The synergistic action of the two enzymes and invertase accelerated the decomposition of sucrose and inhibited the synthesis of sucrose, leading to the accumulation of hexose, which lowered the cellular osmotic potential and enhanced the water uptake capacity. In conclusion, doubled CO2 concentration could alleviate the adverse effects of drought stress and improve the drought tolerance of cucumber seedlings. Such mitigating effect on cucumber was more significant under severe drought stress.

  4. Ciliate and mesozooplankton community response to increasing CO2 levels in the Baltic Sea: insights from a large-scale mesocosm experiment

    Science.gov (United States)

    Lischka, Silke; Bach, Lennart T.; Schulz, Kai-Georg; Riebesell, Ulf

    2017-01-01

    Community approaches to investigating ocean acidification (OA) effects suggest a high tolerance of micro- and mesozooplankton to carbonate chemistry changes expected to occur within this century. Plankton communities in the coastal areas of the Baltic Sea frequently experience pH variations partly exceeding projections for the near future both on a diurnal and seasonal basis. We conducted a large-scale mesocosm CO2 enrichment experiment ( ˜ 55 m3) enclosing the natural plankton community in Tvärminne-Storfjärden for 8 weeks during June-August 2012 and studied community and species-taxon response of ciliates and mesozooplankton to CO2 elevations expected for this century. In addition to the response to fCO2, we also considered temperature and chlorophyll a variations in our analyses. Shannon diversity of ciliates significantly decreased with fCO2 and temperature with a greater dominance of smaller species. The mixotrophic Myrionecta rubra seemed to indirectly and directly benefit from higher CO2 concentrations in the post-bloom phase through increased occurrence of picoeukaryotes (most likely Cryptophytes) and Dinophyta at higher CO2 levels. With respect to mesozooplankton, we did not detect significant effects for either total abundance or for Shannon diversity. The cladocera Bosmina sp. occurred at distinctly higher abundance for a short time period during the second half of the experiment in three of the CO2-enriched mesocosms except for the highest CO2 level. The ratio of Bosmina sp. with empty to embryo- or resting-egg-bearing brood chambers, however, was significantly affected by CO2, temperature, and chlorophyll a. An indirect CO2 effect via increased food availability (Cyanobacteria) stimulating Bosmina sp. reproduction cannot be ruled out. Although increased regenerated primary production diminishes trophic transfer in general, the presence of organisms able to graze on bacteria such as cladocerans may positively impact organic matter transfer to higher

  5. Fast-response CO2 mixing-ratio measurement with an open-path gas analyzer for eddy-flux applications

    Science.gov (United States)

    Bogoev, I.

    2014-12-01

    Infra-red gas analyzers operate on the principle of light absorption and measure the density of the gas in the sensing path. To account for density fluctuations caused by barometric pressure, thermal expansion and contraction, and water-vapor dilution, flux calculations using CO2 density measurements need to be corrected for sensible and latent heat transfer (also known as WPL corrections). In contrast, these corrections are not required if the flux calculation involves CO2 mixing ratio relative to dry air. Historically, CO2 mixing ratio measurements have been available only for analyzers with a closed-path where temperature fluctuations in the air sample are attenuated in the intake tubing to a level that they are adequately measured by a contact thermometer. Open-path gas analyzers are not able to make in situ CO2 mixing-ratio measurements because of the unavailability of a reliable, accurate and fast-response air-temperature sensor in the optical path. A newly developed eddy-flux system integrates an aerodynamic open-path gas analyzer with a sonic anemometer where the sensing volumes of the two instruments coincide. Thus the system has the ability to provide temporally and spatially synchronized fast-response measurements of the 3D wind vector, sonically derived air temperature, CO2 and water vapor densities. When these measurements are combined with a fast-response static pressure measurement an instantaneous in-situ CO2 mixing ratio can be calculated on-line, eliminating the need for density corrections in post-processing. In this study fluxes computed from CO2 mixing-ratio are compared to WPL corrected fluxes using CO2 density. Results from a field inter-comparison with an aspirated temperature probe suggest that accurate, fast response air temperature can be derived from humidity-corrected speed of sound measurements. Biases due to heat exchange with the analyzer surface are evaluated by comparing atmospheric sensible heat flux measurements with a

  6. Responses of growth, photosynthesis and VOC emissions of Pinus tabulaeformis Carr. Exposure to elevated CO2 and/or elevated O3 in an urban area.

    Science.gov (United States)

    Xu, Sheng; Chen, Wei; Huang, Yanqing; He, Xingyuan

    2012-03-01

    Responses of growth, photosynthesis and emission of volatile organic compounds of Pinus tabulaeformis exposed to elevated CO(2) (700 ppm) and O(3) (80 ppb) were studied in open top chambers. Elevated CO(2) increased growth, but it did not significantly (p > 0.05) affect net photosynthetic rate, stomatal conductance, chlorophyll content, the maximum quantum yield of photosystem II, or the effective quantum yield of photosystem II electron transport after 90 d of gas exposure. Elevated O(3) decreased growth (by 42.2% in needle weight and 25.8% in plant height), net photosynthetic rate and stomatal conductance after 90 d of exposure, but its negative effects were alleviated by elevated CO(2). Elevated O(3) significantly (p < 0.05) increased the emission rate of volatile organic compounds, which may be a helpful response to protect photosynthetic apparatus against O(3) damage.

  7. Ventilatory strategies in trauma patients

    Directory of Open Access Journals (Sweden)

    Shubhangi Arora

    2014-01-01

    Full Text Available Lung injury in trauma patients can occur because of direct injury to lung or due to secondary effects of injury elsewhere for example fat embolism from a long bone fracture, or due to response to a systemic insult such as; acute respiratory distress syndrome (ARDS secondary to sepsis or transfusion related lung injury. There are certain special situations like head injury where the primary culprit is not the lung, but the brain and the ventilator strategy is aimed at preserving the brain tissue and the respiratory system takes a second place. The present article aims to delineate the strategies addressing practical problems and challenges faced by intensivists dealing with trauma patients with or without healthy lungs. The lung protective strategies along with newer trends in ventilation are discussed. Ventilatory management for specific organ system trauma are highlighted and their physiological base is presented.

  8. Response of marine viral populations to a nutrient induced phytoplankton bloom at different pCO2 levels

    Directory of Open Access Journals (Sweden)

    R.-A. Sandaa

    2008-04-01

    Full Text Available During the PeECE III mesocosm experiment in 2005 we investigated how the virioplankton community responded to increased levels of nutrients (N and P and CO2. We applied a combination of flow cytometry, Pulsed Field Gel Electrophoresis and degenerate PCR primers to categorize and quantify individual viral populations, and to investigate their temporal dynamics. Species specific and degenerate primers enabled us to identify two specific large dsDNA viruses, EhV and CeV, infecting the haptophytes Emiliania huxleyi and Crysochromulina ericina, respectively. Some of the viral populations detected and enumerated by flow cytometry did not respond to altered CO2-levels, but the abundance of EhV and an unidentified dsDNA virus decreased with increasing CO2 levels. Our results thus indicate that CO2 conditions, or the related change in pH, may affect the marine pelagic food web at the viral level. Our results also demonstrate that in order to unravel ecological problems as how CO2 and nutrient levels affect the relationship between marine algal viruses and their hosts, we need to continue the effort to develop molecular markers used to identify both hosts and viruses.

  9. Response of marine viral populations to a nutrient induced phytoplankton bloom at different pCO2 levels

    Science.gov (United States)

    Larsen, J. B.; Larsen, A.; Thyrhaug, R.; Bratbak, G.; Sandaa, R.-A.

    2008-04-01

    During the PeECE III mesocosm experiment in 2005 we investigated how the virioplankton community responded to increased levels of nutrients (N and P) and CO2. We applied a combination of flow cytometry, Pulsed Field Gel Electrophoresis and degenerate PCR primers to categorize and quantify individual viral populations, and to investigate their temporal dynamics. Species specific and degenerate primers enabled us to identify two specific large dsDNA viruses, EhV and CeV, infecting the haptophytes Emiliania huxleyi and Crysochromulina ericina, respectively. Some of the viral populations detected and enumerated by flow cytometry did not respond to altered CO2-levels, but the abundance of EhV and an unidentified dsDNA virus decreased with increasing CO2 levels. Our results thus indicate that CO2 conditions, or the related change in pH, may affect the marine pelagic food web at the viral level. Our results also demonstrate that in order to unravel ecological problems as how CO2 and nutrient levels affect the relationship between marine algal viruses and their hosts, we need to continue the effort to develop molecular markers used to identify both hosts and viruses.

  10. Near Real-time Ecological Forecasting of Peatland Responses to Warming and CO2 Treatment through EcoPAD-SPRUCE

    Science.gov (United States)

    Huang, Y.; Jiang, J.; Stacy, M.; Ricciuto, D. M.; Hanson, P. J.; Sundi, N.; Luo, Y.

    2016-12-01

    Ecological forecasting is critical in various aspects of our coupled human-nature systems, such as disaster risk reduction, natural resource management and climate change mitigation. Novel advancements are in urgent need to deepen our understandings of ecosystem dynamics, boost the predictive capacity of ecology, and provide timely and effective information for decision-makers in a rapidly changing world. Our Ecological Platform for Assimilation of Data (EcoPAD) facilitates the integration of current best knowledge from models, manipulative experimentations, observations and other modern techniques and provides both near real-time and long-term forecasting of ecosystem dynamics. As a case study, the web-based EcoPAD platform synchronizes real- or near real-time field measurements from the Spruce and Peatland Responses Under Climatic and Environmental Change Experiment (SPRUCE), a whole ecosystem warming and CO2 enrichment treatment experiment, assimilates multiple data streams into process based models, enhances timely feedback between modelers and experimenters, and ultimately improves ecosystem forecasting and makes best utilization of current knowledge. In addition to enable users to (i) estimate model parameters or state variables, (ii) quantify uncertainty of estimated parameters and projected states of ecosystems, (iii) evaluate model structures, (iv) assess sampling strategies, and (v) conduct ecological forecasting, EcoPAD-SPRUCE automated the workflow from real-time data acquisition, model simulation to result visualization. EcoPAD-SPRUCE promotes seamless feedback between modelers and experimenters, hand in hand to make better forecasting of future changes. The framework of EcoPAD-SPRUCE (with flexible API, Application Programming Interface) is easily portable and will benefit scientific communities, policy makers as well as the general public.

  11. Improved responses to elevated CO2 in durum wheat at a low nitrate supply associated with the upregulation of photosynthetic genes and the activation of nitrate assimilation.

    Science.gov (United States)

    Vicente, Rubén; Pérez, Pilar; Martínez-Carrasco, Rafael; Morcuende, Rosa

    2017-07-01

    Elevated CO2 often leads to photosynthetic acclimation, and N availability may alter this response. We investigated whether the coordination of shoot-root N assimilation by elevated CO2 may help to optimize the whole-plant N allocation and maximize photosynthesis in hydroponically-grown durum wheat at two NO3- supplies in interaction with plant development. Transcriptional and biochemical analyses were performed on flag leaves and roots. At anthesis, the improved photosynthetic acclimation response to elevated CO2 at low N was associated with increased Rubisco, chlorophyll and amino acid contents, and upregulation of genes related to their biosynthesis, light reactions and Calvin-Benson cycle, while a decrease was recorded at high N. Despite the decrease in carbohydrates with elevated CO2 at low N and the increase at high N, a stronger upward trend in leaf NR activity was found at low rather than high N. The induction of N recycling-related genes was accompanied by an amino acids decline at high N. At the grain-filling stage, the photosynthetic acclimation to elevated CO2 at high N was associated with the downregulation of both N assimilation, mainly in roots, and photosynthetic genes. At low N, enhanced root N assimilation partly compensated for slower shoot N assimilation and maximized photosynthetic capacity. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Industrial-age changes in atmospheric [CO2] and temperature differentially alter responses of faster- and slower-growing Eucalyptus seedlings to short-term drought.

    Science.gov (United States)

    Lewis, James D; Smith, Renee A; Ghannoum, Oula; Logan, Barry A; Phillips, Nathan G; Tissue, David T

    2013-05-01

    Climate change may alter forest composition by differentially affecting the responses of faster- and slower-growing tree species to drought. However, the combined effects of rising atmospheric CO2 concentration ([CO2]) and temperature on drought responses of trees are poorly understood. Here, we examined interactive effects of temperature (ambient, ambient + °C) and [CO2] (290, 400 and 650mu;l l(-1)) on drought responses of Eucalyptus saligna Sm. (faster-growing) and E. sideroxylon A. Cunn. ex Woolls (slower-growing) seedlings. Drought was imposed via a controlled reduction in soil water over 1-2 weeks, re-watering seedlings when leaves visibly wilted. In ambient temperature, the effect of drought on the light-saturated net photosynthetic rate (Asat) in E. saligna decreased as [CO2] increased from pre-industrial to future concentrations, but rising [CO2] did not affect the response in Eucalyptus sideroxylon. In contrast, elevated temperature exacerbated the effect of drought in reducing Asat in both species. The drought response of Asat reflected changes in stomatal conductance (gs) associated with species and treatment differences in (i) utilization of soil moisture and (ii) leaf area ratio (leaf area per unit plant dry mass). Across [CO2] and temperature treatments, E. saligna wilted at higher soil water potentials compared with E. sideroxylon. Photosynthetic recovery from drought was 90% complete 2 days following re-watering across all species and treatments. Our results suggest that E. saligna (faster-growing) seedlings are more susceptible to drought than E. sideroxylon (slower-growing) seedlings. The greater susceptibility to drought of E. saligna reflected faster drawdown of soil moisture, associated with more leaf area and leaf area ratio, and the ability of E. sideroxylon to maintain higher gs at a given soil moisture. Inclusion of a pre-industrial [CO2] treatment allowed us to conclude that susceptibility of these species to short-term drought

  13. CO2-Neutral Fuels

    NARCIS (Netherlands)

    Goede, A.; van de Sanden, M. C. M.

    2016-01-01

    Mimicking the biogeochemical cycle of System Earth, synthetic hydrocarbon fuels are produced from recycled CO2 and H2O powered by renewable energy. Recapturing CO2 after use closes the carbon cycle, rendering the fuel cycle CO2 neutral. Non-equilibrium molecular CO2 vibrations are key to high energy

  14. Fine root chemistry and decomposition in model communities of north-temperate tree species show little response to elevated atmospheric CO2 and varying soil resource availability.

    Science.gov (United States)

    King, J S; Pregitzer, K S; Zak, D R; Holmes, W E; Schmidt, K

    2005-12-01

    Rising atmospheric [CO2] has the potential to alter soil carbon (C) cycling by increasing the content of recalcitrant constituents in plant litter, thereby decreasing rates of decomposition. Because fine root turnover constitutes a large fraction of annual NPP, changes in fine root decomposition are especially important. These responses will likely be affected by soil resource availability and the life history characteristics of the dominant tree species. We evaluated the effects of elevated atmospheric [CO2] and soil resource availability on the production and chemistry, mycorrhizal colonization, and decomposition of fine roots in an early- and late-successional tree species that are economically and ecologically important in north temperate forests. Open-top chambers were used to expose young trembling aspen (Populus tremuloides) and sugar maple (Acer saccharum) trees to ambient (36 Pa) and elevated (56 Pa) atmospheric CO2. Soil resource availability was composed of two treatments that bracketed the range found in the Upper Lake States, USA. After 2.5 years of growth, sugar maple had greater fine root standing crop due to relatively greater allocation to fine roots (30% of total root biomass) relative to aspen (7% total root biomass). Relative to the low soil resources treatment, aspen fine root biomass increased 76% with increased soil resource availability, but only under elevated [CO2]. Sugar maple fine root biomass increased 26% with increased soil resource availability (relative to the low soil resources treatment), and showed little response to elevated [CO2]. Concentrations of N and soluble phenolics, and C/N ratio in roots were similar for the two species, but aspen had slightly higher lignin and lower condensed tannins contents compared to sugar maple. As predicted by source-sink models of carbon allocation, pooled constituents (C/N ratio, soluble phenolics) increased in response to increased relative carbon availability (elevated [CO2]/low soil resource

  15. The metabolic response of thecosome pteropods from the North Atlantic and North Pacific oceans to high CO2 and low O2

    Science.gov (United States)

    Maas, Amy E.; Lawson, Gareth L.; Aleck Wang, Zhaohui

    2016-11-01

    As anthropogenic activities directly and indirectly increase carbon dioxide (CO2) and decrease oxygen (O2) concentrations in the ocean system, it becomes important to understand how different populations of marine animals will respond. Water that is naturally low in pH, with a high concentration of carbon dioxide (hypercapnia) and a low concentration of oxygen, occurs at shallow depths (200-500 m) in the North Pacific Ocean, whereas similar conditions are absent throughout the upper water column in the North Atlantic. This contrasting hydrography provides a natural experiment to explore whether differences in environment cause populations of cosmopolitan pelagic calcifiers, specifically the aragonitic-shelled pteropods, to have a different physiological response when exposed to hypercapnia and low O2. Using closed-chamber end-point respiration experiments, eight species of pteropods from the two ocean basins were exposed to high CO2 ( ˜ 800 µatm) while six species were also exposed to moderately low O2 (48 % saturated, or ˜ 130 µmol kg-1) and a combined treatment of low O2/high CO2. None of the species tested showed a change in metabolic rate in response to high CO2 alone. Of those species tested for an effect of O2, only Limacina retroversa from the Atlantic showed a response to the combined treatment, resulting in a reduction in metabolic rate. Our results suggest that pteropods have mechanisms for coping with short-term CO2 exposure and that there can be interactive effects between stressors on the physiology of these open ocean organisms that correlate with natural exposure to low O2 and high CO2. These are considerations that should be taken into account in projections of organismal sensitivity to future ocean conditions.

  16. The metabolic response of thecosome pteropods from the North Atlantic and North Pacific oceans to high CO2 and low O2

    Directory of Open Access Journals (Sweden)

    A. E. Maas

    2016-11-01

    Full Text Available As anthropogenic activities directly and indirectly increase carbon dioxide (CO2 and decrease oxygen (O2 concentrations in the ocean system, it becomes important to understand how different populations of marine animals will respond. Water that is naturally low in pH, with a high concentration of carbon dioxide (hypercapnia and a low concentration of oxygen, occurs at shallow depths (200–500 m in the North Pacific Ocean, whereas similar conditions are absent throughout the upper water column in the North Atlantic. This contrasting hydrography provides a natural experiment to explore whether differences in environment cause populations of cosmopolitan pelagic calcifiers, specifically the aragonitic-shelled pteropods, to have a different physiological response when exposed to hypercapnia and low O2. Using closed-chamber end-point respiration experiments, eight species of pteropods from the two ocean basins were exposed to high CO2 ( ∼  800 µatm while six species were also exposed to moderately low O2 (48 % saturated, or  ∼  130 µmol kg−1 and a combined treatment of low O2/high CO2. None of the species tested showed a change in metabolic rate in response to high CO2 alone. Of those species tested for an effect of O2, only Limacina retroversa from the Atlantic showed a response to the combined treatment, resulting in a reduction in metabolic rate. Our results suggest that pteropods have mechanisms for coping with short-term CO2 exposure and that there can be interactive effects between stressors on the physiology of these open ocean organisms that correlate with natural exposure to low O2 and high CO2. These are considerations that should be taken into account in projections of organismal sensitivity to future ocean conditions.

  17. Two tropical conifers show strong growth and water-use efficiency responses to altered CO2 concentration.

    Science.gov (United States)

    Dalling, James W; Cernusak, Lucas A; Winter, Klaus; Aranda, Jorge; Garcia, Milton; Virgo, Aurelio; Cheesman, Alexander W; Baresch, Andres; Jaramillo, Carlos; Turner, Benjamin L

    2016-11-01

    Conifers dominated wet lowland tropical forests 100 million years ago (MYA). With a few exceptions in the Podocarpaceae and Araucariaceae, conifers are now absent from this biome. This shift to angiosperm dominance also coincided with a large decline in atmospheric CO2 concentration (ca). We compared growth and physiological performance of two lowland tropical angiosperms and conifers at ca levels representing pre-industrial (280 ppm), ambient (400 ppm) and Eocene (800 ppm) conditions to explore how differences in ca affect the growth and water-use efficiency (WUE) of seedlings from these groups. Two conifers (Araucaria heterophylla and Podocarpus guatemalensis) and two angiosperm trees (Tabebuia rosea and Chrysophyllum cainito) were grown in climate-controlled glasshouses in Panama. Growth, photosynthetic rates, nutrient uptake, and nutrient use and water-use efficiencies were measured. Podocarpus seedlings showed a stronger (66 %) increase in relative growth rate with increasing ca relative to Araucaria (19 %) and the angiosperms (no growth enhancement). The response of Podocarpus is consistent with expectations for species with conservative growth traits and low mesophyll diffusion conductance. While previous work has shown limited stomatal response of conifers to ca, we found that the two conifers had significantly greater increases in leaf and whole-plant WUE than the angiosperms, reflecting increased photosynthetic rate and reduced stomatal conductance. Foliar nitrogen isotope ratios (δ(15)N) and soil nitrate concentrations indicated a preference in Podocarpus for ammonium over nitrate, which may impact nitrogen uptake relative to nitrate assimilators under high ca SIGNIFICANCE: Podocarps colonized tropical forests after angiosperms achieved dominance and are now restricted to infertile soils. Although limited to a single species, our data suggest that higher ca may have been favourable for podocarp colonization of tropical South America 60

  18. Final Scientific Report DE-FGO3-97ER62460 Stomatal Responses to CO2: A Comparison of Woody and Herbaceous Species in Arid and Humid Climates

    Energy Technology Data Exchange (ETDEWEB)

    Koch, George W.

    2003-12-19

    OAK-B135 The project involved a study of a fundamental response of terrestrial vegetation to rising atmospheric carbon dioxide (CO2) concentration, namely, the change in leaf conductance to gas diffusion associated with a change in the aperture of the microscopic pores (stomata) on the surface of leaves.

  19. Complex spatiotemporal responses of global terrestrial primary production to climate change and increasing atmospheric CO2 in the 21st century.

    Science.gov (United States)

    Pan, Shufen; Tian, Hanqin; Dangal, Shree R S; Zhang, Chi; Yang, Jia; Tao, Bo; Ouyang, Zhiyun; Wang, Xiaoke; Lu, Chaoqun; Ren, Wei; Banger, Kamaljit; Yang, Qichun; Zhang, Bowen; Li, Xia

    2014-01-01

    Quantitative information on the response of global terrestrial net primary production (NPP) to climate change and increasing atmospheric CO2 is essential for climate change adaptation and mitigation in the 21st century. Using a process-based ecosystem model (the Dynamic Land Ecosystem Model, DLEM), we quantified the magnitude and spatiotemporal variations of contemporary (2000s) global NPP, and projected its potential responses to climate and CO2 changes in the 21st century under the Special Report on Emission Scenarios (SRES) A2 and B1 of Intergovernmental Panel on Climate Change (IPCC). We estimated a global terrestrial NPP of 54.6 (52.8-56.4) PgC yr(-1) as a result of multiple factors during 2000-2009. Climate change would either reduce global NPP (4.6%) under the A2 scenario or slightly enhance NPP (2.2%) under the B1 scenario during 2010-2099. In response to climate change, global NPP would first increase until surface air temperature increases by 1.5 °C (until the 2030s) and then level-off or decline after it increases by more than 1.5 °C (after the 2030s). This result supports the Copenhagen Accord Acknowledgement, which states that staying below 2 °C may not be sufficient and the need to potentially aim for staying below 1.5 °C. The CO2 fertilization effect would result in a 12%-13.9% increase in global NPP during the 21st century. The relative CO2 fertilization effect, i.e. change in NPP on per CO2 (ppm) bases, is projected to first increase quickly then level off in the 2070s and even decline by the end of the 2080s, possibly due to CO2 saturation and nutrient limitation. Terrestrial NPP responses to climate change and elevated atmospheric CO2 largely varied among biomes, with the largest increases in the tundra and boreal needleleaf deciduous forest. Compared to the low emission scenario (B1), the high emission scenario (A2) would lead to larger spatiotemporal variations in NPP, and more dramatic and counteracting impacts from climate and increasing

  20. Postural control and ventilatory drive during voluntary hyperventilation and carbon dioxide rebreathing.

    Science.gov (United States)

    David, Pascal; Laval, David; Terrien, Jérémy; Petitjean, Michel

    2012-01-01

    The present study sought to establish links between hyperventilation and postural stability. Eight university students were asked to stand upright under two hyperventilation conditions applied randomly: (1) a metabolic hyperventilation induced by 5 min of hypercapnic-hyperoxic rebreathing (CO(2)-R); and, (2) a voluntary hyperventilation (VH) of 3 min imposed by a metronome set at 25 cycles per min. Recordings were obtained with eyes open, with the subjects standing on a force plate over 20-s periods. Ventilatory response, displacements in the centre of pressure in both the frontal and sagittal planes and fluctuations in the three planes of the ground reaction force were monitored in the time and frequency domains. Postural changes related to respiratory variations were quantified by coherence analysis. Myoelectric activities of the calf muscles were recorded using surface electromyography. Force plate measurements revealed a reduction in postural stability during both CO(2)-R and VH conditions, mainly in the sagittal plane. Coherence analysis provided evidence of a ventilatory origin in the vertical ground reaction force fluctuations during VH. Electromyographic analyses showed different leg muscles strategies, assuming the existence of links between the control of respiration and the control of posture. Our results suggest that the greater disturbing effects caused by voluntary hyperventilation on body balance are more compensated when respiration is under automatic control. These findings may have implications for understanding the organisation of postural and respiratory activities and suggest that stability of the body may be compromised in situations in which respiratory demand increases and requires voluntary control.

  1. Ventilatory Anaerobic Thresholds of Individuals Recovering from Traumatic Brain Injury Compared to Non-Injured Controls

    Science.gov (United States)

    Amonette, William E.; Mossberg, Kurt A.

    2012-01-01

    The purpose of this study was to compare the peak aerobic capacities and ventilatory anaerobic thresholds (VAT) of individuals with a traumatic brain injury (TBI) to age- and gender-matched controls. Methods Nineteen participants that previously suffered a mild to moderate TBI and 19 apparently healthy controls (CON) volunteered as subjects. TBI and CON were matched for age and gender and were similar in weight and BMI. Volunteers performed a maximal graded treadmill test to volitional failure where oxygen consumption (V̇O2), carbon dioxide production (V̇CO2), ventilation (V̇E), and heart rate (HR) were measured continuously. From metabolic and ventilatory data, VAT was measured using a previously described method. VAT and peak exercise responses of participants with a TBI were compared to CON. Results The V̇O2, and V̇CO2at VAT and peak exercise were lower for TBI compared to CON. V̇E was also lower for TBI at VAT and peak exercise. HR was lower for TBI at VAT; however, TBI had similar HR to CON at peak exercise. Conclusions The VAT and peak exercise capacities of participants with a TBI were below the metabolic demands of many routine daily activities. The data suggest that therapeutic interventions for individuals with a TBI should include targeted exercise prescriptions to improve cardiorespiratory fitness. PMID:22935575

  2. Effects of ozone on stomatal responses to environmental parameters (blue light, red light, CO2 and vapour pressure deficit) in three Populus deltoides × Populus nigra genotypes.

    Science.gov (United States)

    Dumont, Jennifer; Spicher, Fabien; Montpied, Pierre; Dizengremel, Pierre; Jolivet, Yves; Le Thiec, Didier

    2013-02-01

    The effect of ozone (O(3)) on stomatal regulation was studied in three Euramerican poplar genotypes (Populus deltoides × Populus nigra: Carpaccio, Cima and Robusta). The impact of O(3) on stomatal conductance responses to variations in blue light, red light, CO(2) concentration and vapour pressure deficit (VPD) was studied. Upon O(3) exposure, a sluggish response of stomatal movements was observed, characterized by slower reactions to increases in blue light intensity, CO(2) concentration and VPD, and lower amplitude of the response to variations in light intensity. That sluggish response should be taken into account in stomatal conductance models for phytotoxic ozone dose (POD(Y)) calculations. The speed of the response to variations in environmental parameters appears as a determining factor of genotype-related sensitivity. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Moderation of [CO2]-induced gas exchange responses by elevated tropospheric O3 in trembling aspen and sugar maple

    Science.gov (United States)

    Pooja Sharma; Anu Sober; Jaak Sober; Gopi P. Podila; Mark E. Kubiske; William J. Mattson; Judson G. Isebrands; David F. Karnosky

    2003-01-01

    The greenhouse gases CO2 and 03 are increasing in the earth's atmosphere. Little is known about long-term impacts of these two co-occurring gases on forest trees. We have been examining the impacts of these two gases on the physiology and growth of trembling aspen (Populus tremuloides) and sugar...

  4. Response of Fagus sylvatica and Picea abies to the interactive effect of neighbor identity and enhanced CO2 levels

    Czech Academy of Sciences Publication Activity Database

    Rolo, V.; Andivia, E.; Pokorný, Radek

    2015-01-01

    Roč. 29, č. 5 (2015), s. 1459-1469 ISSN 0931-1890 R&D Projects: GA MŠk(CZ) LO1415 Institutional support: RVO:67179843 Keywords : mixed-forest * climate change * root morphology * growth * non-structural carbohydrates * CO2 fumigation * plant-to-plant interactions Subject RIV: EH - Ecology, Behaviour Impact factor: 1.706, year: 2015

  5. Strategic responses to CO2 emission reduction targets drive shift in U.S. electric sector water use

    Science.gov (United States)

    The reliance of the U.S. electric sector on water makes this sector vulnerable to climate change and variability. We use the EPAUS9r MARKAL model to investigate changes in U.S. electric sector water withdrawal and consumption through 2055 under alternative energy system-wide CO2...

  6. Competing ecosystem model hypotheses for the CO2 response of a nutrient and water limited mature woodland

    Science.gov (United States)

    Duursma, R.; Medlyn, B. E.; Zaehle, S.; De Kauwe, M. G.; Gimeno, T.; Drake, J.; Macdonald, C.; Singh, B.; Mishurov, M.; Pak, B. C.; Walker, A. P.; Yang, X.; Ellsworth, D.

    2013-12-01

    The long-term response of ecosystems to elevated atmospheric CO2 concentration (eCa) is modulated by the interactions with nutrient cycling and water availability. Here, we set out to evaluate alternative hypotheses for the response of a nutrient and water limited woodland to eCa, using a diverse set of ecosystem models. The EucFACE experiment was established in late 2012 in western Sydney, in a Eucalyptus-dominated native woodland. It is the only FACE site worldwide in mature native woodland. The site is characterized by extremely low nutrient availability (particularly P), frequent occurrence of extended dry periods, and low leaf area index (LAI = ca. 1 m2 m-2). We applied seven ecosystem models to predict, in advance of the experiment, the eCa response of vegetation growing at the EucFACE site. The seven models (GDAY, OCN, SDGVM, CLM4-CN, CLM4-CNP, LPJ-GUESS and CABLE2.0) all include water limitation and nearly all include nutrient limitation. The models embody a range of alternative hypotheses for the effects of eCa on vegetation. The aim was to use the models to quantify the outcomes of these competing hypotheses, and generate focussed questions that can help to guide research at the EucFACE. All models were run with available site inputs, and a historic weather dataset split into a sequence of ';wet' and ';dry' years. We focused on the responses of net primary production (NPP), total evapotranspiration (ET) and water-use efficiency (WUE) to eCa, and the interaction with water availability. The models differed in their predictions of the response of net primary productivity (NPP) to eCa. The hypotheses embedded in the models range from no nutrient limitation to growth, in which case the model predicts a sustained eCa effect on productivity, through to complete nutrient limitation, in which case the model predicts no eCa effect at all. The key processes that would allow us to distinguish among the competing hypotheses were identified as N and P mineralisation

  7. Nitrogen-Efficient and Nitrogen-Inefficient Indian Mustard Showed Differential Expression Pattern of Proteins in Response to Elevated CO2 and Low Nitrogen.

    Science.gov (United States)

    Yousuf, Peerzada Y; Ganie, Arshid H; Khan, Ishrat; Qureshi, Mohammad I; Ibrahim, Mohamed M; Sarwat, Maryam; Iqbal, Muhammad; Ahmad, Altaf

    2016-01-01

    Carbon (C) and nitrogen (N) are two essential elements that influence plant growth and development. The C and N metabolic pathways influence each other to affect gene expression, but little is known about which genes are regulated by interaction between C and N or the mechanisms by which the pathways interact. In the present investigation, proteome analysis of N-efficient and N-inefficient Indian mustard, grown under varied combinations of low-N, sufficient-N, ambient [CO2], and elevated [CO2] was carried out to identify proteins and the encoding genes of the interactions between C and N. Two-dimensional gel electrophoresis (2-DE) revealed 158 candidate protein spots. Among these, 72 spots were identified by matrix-assisted laser desorption ionization-time of flight/time of flight mass spectrometry (MALDI-TOF/TOF). The identified proteins are related to various molecular processes including photosynthesis, energy metabolism, protein synthesis, transport and degradation, signal transduction, nitrogen metabolism and defense to oxidative, water and heat stresses. Identification of proteins like PII-like protein, cyclophilin, elongation factor-TU, oxygen-evolving enhancer protein and rubisco activase offers a peculiar overview of changes elicited by elevated [CO2], providing clues about how N-efficient cultivar of Indian mustard adapt to low N supply under elevated [CO2] conditions. This study provides new insights and novel information for a better understanding of adaptive responses to elevated [CO2] under N deficiency in Indian mustard.

  8. Nitrogen-efficient and nitrogen-inefficient Indian mustard cultivars show differential protein expression in response to elevated CO2 and low nitrogen

    Directory of Open Access Journals (Sweden)

    Peerjada Yasir Yousof

    2016-07-01

    Full Text Available Carbon (C and nitrogen (N are two essential elements that influence plant growth and development. The C and N metabolic pathways influence each other to affect gene expression, but little is known about which genes are regulated by interaction between C and N or the mechanisms by which the pathways interact. In the present investigation, proteome analysis of N-efficient and N-inefficient Indian mustard, grown under varied combinations of low-N, sufficient-N, ambient [CO2] and elevated [CO2] was carried out to identify proteins and the encoding genes of the interactions between C and N. Two-dimensional gel electrophoresis (2-DE revealed 158 candidate protein spots. Among these, 72 spots were identified by matrix-assisted laser desorption ionization-time of flight/time of flight mass spectrometry (MALDI-TOF/TOF. The identified proteins are related to various molecular processes including photosynthesis, energy metabolism, protein synthesis, transport and degradation, signal transduction, nitrogen metabolism and defense to oxidative, water and heat stresses. Identification of proteins like PII-like protein, cyclophilin, elongation factor-TU, oxygen-evolving enhancer protein and rubisco activase offers a peculiar overview of changes elicited by elevated [CO2], providing clues about how N-efficient cultivar of Indian mustard adapt to low N supply under elevated [CO2] conditions. This study provides new insights and novel information for a better understanding of adaptive responses to elevated [CO2] under N deficiency in Indian mustard.

  9. Amelioration of drought-induced negative responses by elevated CO2 in field grown short rotation coppice mulberry (Morus spp.), a potential bio-energy tree crop.

    Science.gov (United States)

    Sekhar, Kalva Madhana; Reddy, Kanubothula Sitarami; Reddy, Attipalli Ramachandra

    2017-05-01

    Present study describes the responses of short rotation coppice (SRC) mulberry, a potential bio-energy tree, grown under interactive environment of elevated CO2 (E) and water stress (WS). Growth in E stimulated photosynthetic performance in well-watered (WW) as well as during WS with significant increases in light-saturated photosynthetic rates (A Sat), water use efficiency (WUEi), intercellular [CO2], and photosystem-II efficiency (F V/F M and ∆F/F M') with concomitant reduction in stomatal conductance (g s) and transpiration (E) compared to ambient CO2 (A) grown plants. Reduced levels of proline, H2O2, and malondialdehyde (MDA) and higher contents of antioxidants including ascorbic acid and total phenolics in WW and WS in E plants clearly demonstrated lesser oxidative damage. Further, A plants showed higher transcript abundance and antioxidant enzyme activities under WW as well as during initial stages of WS (15 days). However, with increasing drought imposition (30 days), A plants showed down regulation of antioxidant systems compared to their respective E plants. These results clearly demonstrated that future increased atmospheric CO2 enhances the photosynthetic potential and also mitigate the drought-induced oxidative stress in SRC mulberry. In conclusion, mulberry is a potential bio-energy tree crop which is best suitable for short rotation coppice forestry-based mitigation of increased [CO2] levels even under intermittent drought conditions, projected to prevail in the fast-changing global climate.

  10. A reactive transport model for the geochemical response, detection and potential mitigation of CO2 leakage into a confined aquifer

    Science.gov (United States)

    Maher, K.; Druhan, J. L.; Vialle, S.; Benson, S. M.; Agarwal, A.

    2013-12-01

    Long-term storage of anthropogenic CO2 in the subsurface generally assumes that caprock formations will serve as physical barriers to upward migration of CO2. Stability and coherence of the caprocks are thus important criteria for site selection, but caprock integritycannot be guaranteed with total certainty over the lifetime of the project. As a result, carbon capture and storage projects require reliable techniques to monitor geologic storage sites for newly formed leaks, and the ability to rapidly deploy mitigation measures should leakage occur. Here, we present two-dimensional reactive transport simulations to evaluate the hydrogeochemical characteristics of a newly formed CO2 leak into an overlying reservoir. Simulations use the ToughReact multi-component reactive transport code and hypothetical reservoir characteristics. We focus on the comparatively short time period of days to months following formation of the leak to consider (1) geochemical shifts in formation water indicative of the leak, (2) hydrodynamics of pumping wells in the vicinity of the leak, and (3) delivery of a sealant to the leak through an adjacent well bore. Our results suggest that characteristic shifts in pH and dissolved inorganic carbon might be detected in down-gradient mentoring wells prior to the breakthrough of CO2, and could offer a potential means of identifying small and newly formed leaks. Injecting water into the aquifer through pumping wells in the vicinity of the leak provides a hydrodynamic control that can prevent CO2 from reaching the top of the reservoir, but this action will likely have only minor influence on the rate of leakage through the caprock defect. Injection of a hypothetical sealant through an adjacent pumping well is considered using an aqueous solute with pH-dependent equilibrium constraints such that the species is soluble in the basic pH range but forms a precipitate at neutral to acidic pH conditions associated with CO2-rich water. Injection of this

  11. Comparative determination of ventilatory efficiency from constant load and incremental exercise testing.

    Science.gov (United States)

    Algul, S; Ugur, F A; Ayar, A; Ozcelik, O

    2017-08-15

    The analysis of the relationships between minute ventilation (VE) to CO2 output (VCO2), referred to as ventilatory efficiency, in response to incremental exercise testing, is considered a useful index for assessing the presence and severity of cardiopulmonary and metabolic diseases. The effects of constant load exercise testing performed at work intensity associated with anaerobic threshold (AT) and respiratory compensation points (RCP), on the accurate measurements of ventilatory efficiency are not well known. The aim of this present study was to investigate the reliability of the VE/VCO2 ratio obtained from constant load exercise tests performed with two important metabolic rates (at the AT and RCP) and compare it to that of those of incremental exercise tests. A total of 20 young male (20.8±0.4 yr) subjects initially performed an incremental exercise test and then two constant load exercise tests, on different days. Respiratory and pulmonary gas exchange variables were used to estimate AT and RCP. A paired t-test was used to analyse data. AT and RCP (average) occurred the at 60% and at 71% of peak O2 uptake, respectively. The lowest VE/VCO2 ratio recorded within the first 2 minutes of constant load exercise tests with a work load of AT (26.4±0.3) and RCP (26.7±0.5) was not statistically different from the lowest ratio obtained from the incremental exercise tests (26.0±0.7). In the constant load exercise test, despite the different metabolic rates, the increase in ventilation corresponded closely with the increase in CO2 production, reflecting an optimal ventilation and perfusion ratio. Clinicians should consider the constant load exercise test work load associated with AT and RCP as it provides a meaningful lowest value for ventilatory efficiency.

  12. Ventilatory response to added dead space and position in preterm infants at high risk age for SIDS.

    Science.gov (United States)

    Saiki, Tolulope; Hannam, Simon; Rafferty, Gerrard F; Milner, Anthony D; Greenough, Anne

    2011-03-01

    The vulnerability of prematurely born infants to sudden infant death syndrome (SIDS) in the prone position might be explained by a reduced ability to respond to a stress, such as hypercarbia, in that position; our objective, therefore, was to further explore the influence of position on the response to a stress. The ability of prematurely born infants to respond to added dead space in the prone compared to the supine position would be impaired at the high risk age for SIDS. Twenty infants, median gestational age of 30 (range 24-32) weeks were studied at a median postmenstrual age (PMA) of 45 weeks. In addition, comparisons were made to the results of 25 infants studied at 36 weeks PMA. Infants were studied supine and prone. Breath by breath minute volume was measured at baseline and after a dead space was incorporated into the breathing circuit; the time constant of the response was calculated. The pressure generated in the first 100 msec of an occlusion (P0.1 ), the maximum inspiratory pressure during an airway occlusion and functional residual capacity (FRC) were also measured in both positions. The median time constant was longer (38 (range 15-85) vs. 26 (range 2-40) sec (P = 0.002)). P0.1 lower (P = 0.003) and FRC higher (P = 0.031) in the prone compared to the supine position. In the prone position, the time constant correlated with PMA (P = 0.047), that is, the rate of response to added dead space was significantly damped with increasing postnatal age up to the critical age for SIDS. The dampened rate of response to added dead space in the prone compared to the supine position lends support to the hypothesis that a poorer response to a stress may contribute to prematurely born infants increased risk of SIDS in the prone position. Copyright © 2010 Wiley-Liss, Inc.

  13. The response of soil CO2 fluxes to progressively excluding vertebrate and invertebrate herbivores depends on ecosystem type

    Science.gov (United States)

    Anita C. Risch; Alan G. Haynes; Matt D. Busse; Flurin Filli; Martin Schütz

    2013-01-01

    Grasslands support large populations of herbivores and store up to 30% of the world’s soil carbon (C). Thus, herbivores likely play an important role in the global C cycle. However, most studies on how herbivory impacts the largest source of C released from grassland soils—soil carbon dioxide (CO2) emissions—only considered the role of large...

  14. Fractional CO2 laser resurfacing for atrophic acne scars: a randomized controlled trial with blinded response evaluation.

    Science.gov (United States)

    Hedelund, Lene; Haak, Christina S; Togsverd-Bo, Katrine; Bogh, Morten K; Bjerring, Peter; Haedersdal, Merete

    2012-08-01

    The treatment of acne scars with fractional CO(2) lasers is gaining increasing impact, but has so far not been compared side-by-side to untreated control skin. In a randomized controlled study to examine efficacy and adverse effects of fractional CO(2) laser resurfacing for atrophic acne scars compared to no treatment. Patients (n = 13) with atrophic acne scars in two intra-individual areas of similar sizes and appearances were randomized to (i) three monthly fractional CO(2) laser treatments (MedArt 610; 12-14 W, 48-56 mJ/pulse, 13% density) and (ii) no treatment. Blinded on-site evaluations were performed by three physicians on 10-point scales. Endpoints were change in scar texture and atrophy, adverse effects, and patient satisfaction. Preoperatively, acne scars appeared with moderate to severe uneven texture (6.15 ± 1.23) and atrophy (5.72 ± 1.45) in both interventional and non-interventional control sites, P = 1. Postoperatively, lower scores of scar texture and atrophy were obtained at 1 month (scar texture 4.31 ± 1.33, P scar texture 4.26 ± 1.97, P scar texture 3.89 ± 1.7, P scar texture to be mild or moderately improved. Adverse effects were minor. In this single-blinded randomized controlled trial we demonstrated that moderate to severe atrophic acne scars can be safely improved by ablative fractional CO(2) laser resurfacing. The use of higher energy levels might have improved the results and possibly also induced significant adverse effects. Copyright © 2012 Wiley Periodicals, Inc.

  15. Possible Responsibility of Silicone Materials for Degradation of the CO2 Removal System in the International Space Station

    Science.gov (United States)

    Baeza, Mario; Sharma, Hemant; Borrok, David; Ren, Mingua; Pannell, Keith

    2011-01-01

    From data concerning the degradation of the CO2 removal system in the International Space Station (ISS) two important features were apparent: (1) The atmosphere within the International Space Station (ISS) contained many organic compounds including alcohols, halocarbons, aldehydes, esters, and ketones, inter alia. Various cyclosiloxanes Dn, hexamethylcyclotrisiloxane (D3) and its higher homologs (D4) and (D5) are also present presumably due to offgassing. (2) Screens within the zeolite-containing canisters, used for the removal of CO2, exhibited partial clogging due to zeolitic fragments (dust) along with "sticky" residues, that in toto significantly reduced the efficiency of the CO2 removal process. Samples of the ISS fresh zeolite, used zeolite, filter clogging zeolite particles and residual polymeric materials were examined using, inter alia, NMR, EM and HRSEM. These data were compared to equivalent samples obtained prior and subsequent to Dn polymerization experiments performed in our laboratories using the clean ISS zeolite samples as catalyst. Polysiloxane materials produced were essentially equivalent in the two cases and the EM images demonstrate a remarkable similarity between the ISS filter zeolite samples and the post-polymerization zeolite material from our experiments. In this regard even the changes in the Al/Si ratio from the virgin zeolite material to the filter samples and the post-polymerization laboratory samples samples is noteworthy. This research was supported by a contract from the Boeing Company

  16. Assessing the Response to Inhaled Albuterol by Monitoring Patient Effort-Related Trends With a Servo-I Ventilator in Neurally Adjusted Ventilatory Assist Mode: A Case Presentation.

    Science.gov (United States)

    Snow, Timothy Matthew; Brinck, Matthew J

    2015-12-01

    Infants with chronic lung disease tend to be difficult to care for due to the heterogeneous nature of both their disease and the treatments required. Multiple types of medications, treatments, and nursing interventions are often needed to attain clinical success, and it is frequently difficult to discern which are effective versus the ones that offer no benefit. This article presents a case study that chronicles the care of an infant with chronic lung disease treated with albuterol. An innovative form of ventilation with monitoring of the electrical activity of the diaphragm with a special sensor-embedded catheter is used to assess the effectiveness of albuterol administration. This case study presents the monitoring of the effectiveness of albuterol in an infant with chronic lung disease measuring the electrical activity of the diaphragm catheter (Edi) and the various monitoring systems on the Servo-i ventilator in Neurally Adjusted Ventilatory Assist (NAVA) Mode. The clinicians followed various respiratory trends monitored by the Servo-i ventilator after albuterol dosing to document the clinical utility of using albuterol in this infant. The monitoring provided by NAVA showed an improvement in both lung mechanics and clinical condition immediately after albuterol administration. The infant had a positive response to albuterol dosing that subsequently led to reduced length of stay, reduced costs, and reduced family anxiety. This type of monitoring could help nurses and clinicians discern whether a given treatment or medication was effective. This method of clinical monitoring could provide a means to assess clinical utility of respiratory medications, treatments, and nursing interventions in certain populations of neonates and infants. The impact of objective monitoring on required sedation, weight gain, ventilator days, length of hospitalization, and overall hospital costs are other possible areas for future research.

  17. Anxiogenic CO2 Stimulus Elicits Exacerbated Hot Flash-like Responses in a Rat Menopause Model and Hot Flashes in Menopausal Women

    Science.gov (United States)

    Federici, Lauren M.; Roth, Sarah Dorsey; Krier, Connie; Fitz, Stephanie D.; Skaar, Todd; Shekhar, Anantha; Carpenter, Janet S.; Johnson, Philip L.

    2016-01-01

    Objective Since longitudinal studies determined that anxiety is a strong risk factor for hot flashes, we hypothesized that an anxiogenic stimulus that signals air hunger (hypercapnic, normoxic gas) would trigger an exacerbated hot flash-associated increase in tail skin temperature (TST) in a rat ovariectomy (OVEX) model of surgical menopause and hot flashes in symptomatic menopausal women. We also assessed TST responses in OVEX serotonin transporter (SERT)+/− rats that models a common polymorphism that is associated with increased climacteric symptoms in menopausal women and increases in anxiety traits. Methods OVEX and sham-OVEX rats (initial experiment) and wildtype and SERT+/− OVEX rats (subsequent experiment) were exposed to a 5 min infusion of 20%CO2 normoxic gas while measuring TST. Menopausal women were given brief 20% and 35%CO2 challenges, and hot flashes were self-reported and objectively verified. Results Compared to controls, OVEX rats had exacerbated increases in TST, and SERT+/− OVEX rats had prolonged TST increases following CO2. Most women reported mild/moderate hot flashes after CO2 challenges, and the hot flash severity to CO2 was positively correlated with daily hot flash frequency. Conclusions The studies demonstrate that this anxiogenic stimulus is capable of inducing cutaneous vasomotor responses in OVEX rats, and eliciting hot flashes in menopausal women. In rats, the severity of the response was mediated by loss of ovarian function and increased anxiety traits (SERT+/−), and, in women, by daily hot flash frequency. These findings may provide insights into anxiety related triggers and genetic risk factors for hot flashes in thermoneutral environments. PMID:27465717

  18. Anxiogenic CO2 stimulus elicits exacerbated hot flash-like responses in a rat menopause model and hot flashes in postmenopausal women.

    Science.gov (United States)

    Federici, Lauren M; Roth, Sarah Dorsey; Krier, Connie; Fitz, Stephanie D; Skaar, Todd; Shekhar, Anantha; Carpenter, Janet S; Johnson, Philip L

    2016-11-01

    As longitudinal studies determined that anxiety is a strong risk factor for hot flashes, we hypothesized that an anxiogenic stimulus that signals air hunger (hypercapnic, normoxic gas) would trigger an exacerbated hot flash-associated increase in tail skin temperature (TST) in a rat ovariectomy (OVEX) model of surgical menopause and hot flashes in symptomatic postmenopausal women. We also assessed TST responses in OVEX serotonin transporter (SERT) rats that models a common polymorphism that is associated with increased climacteric symptoms in postmenopausal women and increases in anxiety traits. OVEX and sham-OVEX rats (initial experiment) and wildtype and SERT OVEX rats (subsequent experiment) were exposed to a 5-minute infusion of 20% carbon dioxide (CO2) normoxic gas while measuring TST. Postmenopausal women were given brief 20% and 35% CO2 challenges, and hot flashes were self-reported and objectively verified. Compared to controls, OVEX rats had exacerbated increases in TST, and SERT OVEX rats had prolonged TST increases following CO2. Most women reported mild/moderate hot flashes after CO2 challenges, and the hot flash severity to CO2 was positively correlated with daily hot flash frequency. The studies demonstrate that this anxiogenic stimulus is capable of inducing cutaneous vasomotor responses in OVEX rats, and eliciting hot flashes in postmenopausal women. In rats, the severity of the response was mediated by loss of ovarian function and increased anxiety traits (SERT), and, in women, by daily hot flash frequency. These findings may provide insights into anxiety-related triggers and genetic risk factors for hot flashes in thermoneutral environments.

  19. Leaf d15N as a physiological indicator of the responsiveness of N2-fixing alfalfa plants to elevated [CO2], temperature and low water availability

    Directory of Open Access Journals (Sweden)

    Idoia eAriz

    2015-08-01

    Full Text Available The natural 15N/14N isotope composition (δ15N of a tissue is a consequence of its N source and N physiological mechanisms in response to the environment. It could potentially be used as a tracer of N metabolism in plants under changing environmental conditions, where primary N metabolism may be complex, and losses and gains of N fluctuate over time. In order to test the utility of δ15N as an indicator of plant N status in N2-fixing plants grown under various environmental conditions, alfalfa (Medicago sativa L. plants were subjected to distinct conditions of [CO2] (400 versus 700 mol mol-1, temperature (ambient versus ambient + 4ºC and water availability (fully watered versus water deficiency - WD. As expected, increased [CO2] and temperature stimulated photosynthetic rates and plant growth, whereas these parameters were negatively affected by WD. The determination of δ15N in leaves, stems, roots and nodules showed that leaves were the most representative organs of the plant response to increased [CO2] and WD. Depletion of heavier N isotopes in plants grown under higher [CO2] and WD conditions reflected decreased transpiration rates, but could also be related to a higher N demand in leaves, as suggested by the decreased leaf N and total soluble protein (TSP contents detected at 700 mol mol-1 [CO2] and WD conditions. In summary, leaf δ15N provides relevant information integrating parameters which condition plant responsiveness (e.g. photosynthesis, TSP, N demand and water transpiration to environmental conditions.

  20. Fine Root Growth and Vertical Distribution in Response to Elevated CO2, Warming and Drought in a Mixed Heathland–Grassland

    DEFF Research Database (Denmark)

    Arndal, Marie Frost; Tolver, Anders; Larsen, Klaus Steenberg

    2018-01-01

    in single-factor experiments. In a Danish heathland ecosystem, we investigated both individual and combined effects of elevated CO2, warming and drought on fine root length, net production and standing biomass by the use of minirhizotrons, ingrowth cores and soil coring. Warming increased the net root......Belowground plant responses have received much less attention in climate change experiments than aboveground plant responses, thus hampering a holistic understanding of climate change effects on plants and ecosystems. In addition, responses of plant roots to climate change have mostly been studied...... production from ingrowth cores, but decreased fine root number and length in minirhizotrons, whereas there were no significant main effects of drought. Across all treatments and soil depths, CO2 stimulated both the total fine root length (+44%) and the number of roots observed (+39%), with highest relative...

  1. Ventilatory physiology of children and adolescents with anxiety disorders.

    Science.gov (United States)

    Pine, D S; Coplan, J D; Papp, L A; Klein, R G; Martinez, J M; Kovalenko, P; Tancer, N; Moreau, D; Dummit, E S; Shaffer, D; Klein, D F; Gorman, J M

    1998-02-01

    Abnormalities in ventilatory physiology have been noted in adults with panic disorder. We tested the hypothesis that abnormalities in ventilatory physiology differentiate children and adolescents with anxiety disorders from psychiatrically healthy children. Ventilatory physiology was monitored with a canopy apparatus during room-air breathing and 15 minutes of carbon dioxide exposure in 33 children and adolescents comprising 18 probands with an anxiety disorder and 15 psychiatrically healthy children. During room-air breathing, probands had significantly larger minute ventilation, larger tidal volumes, and more variable breathing patterns than healthy comparisons, but the groups did not differ in end-tidal carbon dioxide or respiratory rate. During carbon dioxide challenge, probands exhibited larger minute ventilation and respiratory rate responses relative to comparisons. These findings on the association between ventilatory physiology and anxiety disorders in children and adolescents are consistent with results from studies of adults with panic disorder.

  2. Explaining global increases in water use efficiency: why have we overestimated responses to rising atmospheric CO(2 in natural forest ecosystems?

    Directory of Open Access Journals (Sweden)

    Lucas C R Silva

    Full Text Available BACKGROUND: The analysis of tree-ring carbon isotope composition (δ(13C has been widely used to estimate spatio-temporal variations in intrinsic water use efficiency (iWUE of tree species. Numerous studies have reported widespread increases in iWUE coinciding with rising atmospheric CO(2 over the past century. While this could represent a coherent global response, the fact that increases of similar magnitude were observed across biomes with no apparent effect on tree growth raises the question of whether iWUE calculations reflect actual physiological responses to elevated CO(2 levels. METHODOLOGY/RESULTS: Here we use Monte Carlo simulations to test if an artifact of calculation could explain observed increases in iWUE. We show that highly significant positive relationships between iWUE and CO(2 occur even when simulated data (randomized δ(13C values spanning the observed range are used in place of actual tree-ring δ(13C measurements. From simulated data sets we calculated non-physiological changes in iWUE from 1900 to present and across a 4000 m altitudinal range. This generated results strikingly similar to those reported in recent studies encompassing 22 species from tropical, subtropical, temperate, boreal and mediterranean ecosystems. Only 6 of 49 surveyed case studies showed increases in iWUE significantly higher than predicted from random values. CONCLUSIONS/SIGNIFICANCE: Our results reveal that increases in iWUE estimated from tree-ring δ(13C occur independently of changes in (13C discrimination that characterize physiological responses to elevated CO(2. Due to a correlation with CO(2 concentration, which is used as an independent factor in the iWUE calculation, any tree-ring δ(13C data set would inevitably generate increasing iWUE over time. Therefore, although consistent, previously reported trends in iWUE do not necessarily reflect a coherent global response to rising atmospheric CO(2. We discuss the significance of these findings

  3. The selective expression of carbonic anhydrase genes of Aspergillus nidulans in response to changes in mineral nutrition and CO2 concentration.

    Science.gov (United States)

    Xiao, Leilei; Lian, Bin; Dong, Cuiling; Liu, Fanghua

    2016-02-01

    Carbonic anhydrase (CA) plays an important role in the formation and evolution of life. However, to our knowledge, there has been no report on CA isoenzyme function differentiation in fungi. Two different CA gene sequences in Aspergillus nidulans with clear genetic background provide us a favorable basis for studying function differentiation of CA isoenzymes. Heterologously expressed CA1 was used to test its weathering ability on silicate minerals and real-time quantitative PCR was used to detect expression of the CA1 and CA2 genes at different CO2 concentrations and in the presence of different potassium sources. The northern blot method was applied to confirm the result of CA1 gene expression. Heterologously expressed CA1 significantly promoted dissolution of biotite and wollastonite, and CA1 gene expression increased significantly in response to soluble K-deficiency. The northern blot test further showed that CA1 participated in K-feldspar weathering. In addition, the results showed that CA2 was primary involved in adapting to CO2 concentration change. Taken together, A. nidulans can choose different CA to meet their survival needs, which imply that some environmental microbes have evolved different CAs to adapt to changes in CO2 concentration and acquire mineral nutrition so that they can better adapt to environmental changes. Inversely, their adaption may impact mineral weathering and/or CO2 concentration, and even global change. © 2015 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

  4. Responses of methanogenic and methanotrophic communities to elevated atmospheric CO2 and temperature in a paddy field

    Directory of Open Access Journals (Sweden)

    Yuan Liu

    2016-11-01

    Full Text Available Although climate change is predicted to affect methane (CH4 emissions in paddy soil, the dynamics of methanogens and methanotrophs in paddy fields under climate change have not yet been fully investigated. To address this issue, a multifactor climate change experiment was conducted in a Chinese paddy field using the following experimental treatments: (1 enrichment of atmospheric CO2 concentrations (500 ppm, CE, (2 canopy air warming (2°C above the ambient, WA, (3 combined CO2 enrichment and warming (CW, and (4 ambient conditions (CK. We analyzed the abundance of methanogens and methanotrophs, community structures, CH4 production and oxidation potentials, in situ CH4 emissions using real-time PCR, T-RFLP and clone library techniques, as well as biochemical assays. Compared to the control under CE and CW treatments, CH4 production potential, methanogenic gene abundance and soil microbial biomass carbon (SMBC significantly increased; the methanogenic community however remained stable. The canopy air warming treatment only had an effect on CH4 oxidation potential at the ripening stage. Phylogenic analysis indicated that methanogens in the rhizosphere were dominated by Methanosarcina, Methanocellales, Methanobacteriales and Methanomicrobiales, while methanotrophic sequences were classified as Methylococcus, Methylocaldum, Methylomonas, Methylosarcina (Type I and Methylocystis (Type II. However, the relative abundance of Methylococcus (Type I decreased under CE and CW treatments and the relative abundance of Methylocystis (Type II increased. The in situ CH4 fluxes indicated similar seasonal patterns between treatments; both CE and CW increased CH4 emissions. In conclusion results suggest that methanogens and methanotrophs respond differently to elevated atmospheric CO2 concentrations and warming, thus adding insights into the effects of simulated global climate change on CH4 emissions in paddy fields.

  5. Growth and Development of Larval Bay Scallops (Argopecten irradians) in Response to Early Exposure to High CO2

    Science.gov (United States)

    2013-02-01

    coral   reefs  and  other  marine  calcifiers:  A  guide   for...unlimited. Edward A. Boyle MIT Director of Joint Program Approved for Distribution: Mark E. Hahn, Chair Department of Biology James A. Yoder WHO I Dean...CO2       by     Meredith  Megan  White     Submitted  to  the  Department  of   Biology   on  January

  6. Validation of a Transcutaneous CO2 Monitor in Adult Patients with Chronic Respiratory Failure

    NARCIS (Netherlands)

    Hazenberg, A.; Zijlstra, J. G.; Kerstjens, H. A. M.; Wijkstra, P. J.

    2011-01-01

    Background: Home mechanical ventilation is usually started in hospital as arterial blood gas sampling is deemed necessary to monitor CO2 and O-2 adequately during institution of ventilatory support. A non-invasive device to reliably measure CO2 transcutaneously would alleviate the need for high care

  7. Graphite and ablative material response to CO2 laser, carbon-arc, and xenon-arc radiation

    Science.gov (United States)

    Brewer, W. D.

    1976-01-01

    The behavior was investigated of graphite and several charring ablators in a variety of high-radiative heat-flux environments. A commercial-grade graphite and nine state-of-the-art charring ablators were subjected to various radiative environments produced by a CO2 laser and a carbon arc. Graphite was also tested in xenon-arc radiation. Heat-flux levels ranged from 10 to 47 MW/sq m. Tests were conducted in air, nitrogen, helium, and a CO2-N2 mixture which simulated the Venus atmosphere. The experimental results were compared with theoretical results obtained with a one-dimensional charring-ablator analysis and a two-dimensional subliming-ablator analysis. Neither the graphite nor the charring ablators showed significant differences in appearance or microstructure after testing in the different radiative environments. The performance of phenolic nylon and graphite was predicted satisfactorily with existing analyses and published material property data. Good agreement between experimental and analytical results was obtained by using sublimation parameters from a chemical nonequilibrium analysis of graphite sublimation. Some charring ablators performed reasonably well and could withstand radiative fluxes of the level encountered in certain planetary entries. Other materials showed excessive surface recession and/or large amounts of cracking and spalling, and appear to be unsuitable for severe radiative environments.

  8. Diverging temperature responses of CO2 assimilation and plant development explain the overall effect of temperature on biomass accumulation in wheat leaves and grains.

    Science.gov (United States)

    Collins, Nicholas C; Parent, Boris

    2017-01-09

    There is a growing consensus in the literature that rising temperatures influence the rate of biomass accumulation by shortening the development of plant organs and the whole plant and by altering rates of respiration and photosynthesis. A model describing the net effects of these processes on biomass would be useful, but would need to reconcile reported differences in the effects of night and day temperature on plant productivity. In this study, the working hypothesis was that the temperature responses of CO2 assimilation and plant development rates were divergent, and that their net effects could explain observed differences in biomass accumulation. In wheat (Triticum aestivum) plants, we followed the temperature responses of photosynthesis, respiration and leaf elongation, and confirmed that their responses diverged. We measured the amount of carbon assimilated per "unit of plant development" in each scenario and compared it to the biomass that accumulated in growing leaves and grains. Our results suggested that, up to a temperature optimum, the rate of any developmental process increased with temperature more rapidly than that of CO2 assimilation and that this discrepancy, summarised by the CO2 assimilation rate per unit of plant development, could explain the observed reductions in biomass accumulation in plant organs under high temperatures. The model described the effects of night and day temperature equally well, and offers a simple framework for describing the effects of temperature on plant growth. Published by Oxford University Press on behalf of the Annals of Botany Company.

  9. Interaction of CO2 concentrations and water stress in semiarid plants causes diverging response in instantaneous water use efficiency and carbon isotope composition

    Science.gov (United States)

    Zhao, Na; Meng, Ping; He, Yabing; Yu, Xinxiao

    2017-07-01

    In the context of global warming attributable to the increasing levels of CO2, severe drought may be more frequent in areas that already experience chronic water shortages (semiarid areas). This necessitates research on the interactions between increased levels of CO2 and drought and their effect on plant photosynthesis. It is commonly reported that 13C fractionation occurs as CO2 gas diffuses from the atmosphere to the substomatal cavity. Few researchers have investigated 13C fractionation at the site of carboxylation to cytoplasm before sugars are exported outward from the leaf. This process typically progresses in response to variations in environmental conditions (i.e., CO2 concentrations and water stress), including in their interaction. Therefore, saplings of two typical plant species (Platycladus orientalis and Quercus variabilis) from semiarid areas of northern China were selected and cultivated in growth chambers with orthogonal treatments (four CO2 concentration ([CO2]) × five soil volumetric water content (SWC)). The δ13C of water-soluble compounds extracted from leaves of saplings was determined for an assessment of instantaneous water use efficiency (WUEcp) after cultivation. Instantaneous water use efficiency derived from gas-exchange measurements (WUEge) was integrated to estimate differences in δ13C signal variation before leaf-level translocation of primary assimilates. The WUEge values in P. orientalis and Q. variabilis both decreased with increased soil moisture at 35-80 % of field capacity (FC) and increased with elevated [CO2] by increasing photosynthetic capacity and reducing transpiration. Instantaneous water use efficiency (iWUE) according to environmental changes differed between the two species. The WUEge in P. orientalis was significantly greater than that in Q. variabilis, while an opposite tendency was observed when comparing WUEcp between the two species. Total 13C fractionation at the site of carboxylation to cytoplasm before sugar

  10. Interaction of CO2 concentrations and water stress in semiarid plants causes diverging response in instantaneous water use efficiency and carbon isotope composition

    Directory of Open Access Journals (Sweden)

    N. Zhao

    2017-07-01

    Full Text Available In the context of global warming attributable to the increasing levels of CO2, severe drought may be more frequent in areas that already experience chronic water shortages (semiarid areas. This necessitates research on the interactions between increased levels of CO2 and drought and their effect on plant photosynthesis. It is commonly reported that 13C fractionation occurs as CO2 gas diffuses from the atmosphere to the substomatal cavity. Few researchers have investigated 13C fractionation at the site of carboxylation to cytoplasm before sugars are exported outward from the leaf. This process typically progresses in response to variations in environmental conditions (i.e., CO2 concentrations and water stress, including in their interaction. Therefore, saplings of two typical plant species (Platycladus orientalis and Quercus variabilis from semiarid areas of northern China were selected and cultivated in growth chambers with orthogonal treatments (four CO2 concentration ([CO2]  ×  five soil volumetric water content (SWC. The δ13C of water-soluble compounds extracted from leaves of saplings was determined for an assessment of instantaneous water use efficiency (WUEcp after cultivation. Instantaneous water use efficiency derived from gas-exchange measurements (WUEge was integrated to estimate differences in δ13C signal variation before leaf-level translocation of primary assimilates. The WUEge values in P. orientalis and Q.  variabilis both decreased with increased soil moisture at 35–80 % of field capacity (FC and increased with elevated [CO2] by increasing photosynthetic capacity and reducing transpiration. Instantaneous water use efficiency (iWUE according to environmental changes differed between the two species. The WUEge in P. orientalis was significantly greater than that in Q. variabilis, while an opposite tendency was observed when comparing WUEcp between the two species. Total 13C fractionation at the site of

  11. Enhancement of the Stomatal Response to Blue Light by Red Light, Reduced Intercellular Concentrations of CO(2), and Low Vapor Pressure Differences.

    Science.gov (United States)

    Assmann, S M

    1988-05-01

    The effects of environmental parameters on the blue light response of stomata were studied by quantifying transient increases in stomatal conductance in Commelina communis following 15 seconds by 0.100 millimole per square meter per second pulses of blue light. Because conductance increases were not observed following red light pulses of the same or greater (30 seconds by 0.200 millimole per square meter per second) fluences, the responses observed could be reliably attributed to the specific blue light response of the guard cells, rather than to guard cell chlorophyll. In both Paphiopedilum harrisianum, which lacks guard cell chloroplasts, and Commelina, the blue light response was enhanced by 0.263 millimole per square meter per second continuous background red light. Thus, the blue light response and its enhancement do not require energy derived from red-light-driven photophosphorylation by the guard cell chloroplasts. In Commelina, reduction of the intercellular concentration of CO(2) by manipulation of ambient CO(2) concentrations resulted in an enhanced blue light response. In both Commelina and Paphiopedilum, the blue light response was decreased by an increased vapor pressure difference. The magnitude of blue-light-specific stomatal opening thus appears to be sensitive to environmental conditions that affect the carbon and water status of the plant.

  12. Enhancement of the Stomatal Response to Blue Light by Red Light, Reduced Intercellular Concentrations of CO2, and Low Vapor Pressure Differences 1

    Science.gov (United States)

    Assmann, Sarah M.

    1988-01-01

    The effects of environmental parameters on the blue light response of stomata were studied by quantifying transient increases in stomatal conductance in Commelina communis following 15 seconds by 0.100 millimole per square meter per second pulses of blue light. Because conductance increases were not observed following red light pulses of the same or greater (30 seconds by 0.200 millimole per square meter per second) fluences, the responses observed could be reliably attributed to the specific blue light response of the guard cells, rather than to guard cell chlorophyll. In both Paphiopedilum harrisianum, which lacks guard cell chloroplasts, and Commelina, the blue light response was enhanced by 0.263 millimole per square meter per second continuous background red light. Thus, the blue light response and its enhancement do not require energy derived from red-light-driven photophosphorylation by the guard cell chloroplasts. In Commelina, reduction of the intercellular concentration of CO2 by manipulation of ambient CO2 concentrations resulted in an enhanced blue light response. In both Commelina and Paphiopedilum, the blue light response was decreased by an increased vapor pressure difference. The magnitude of blue-light-specific stomatal opening thus appears to be sensitive to environmental conditions that affect the carbon and water status of the plant. PMID:16666108

  13. CO2NNIE

    DEFF Research Database (Denmark)

    Krogh, Benjamin Bjerre; Andersen, Ove; Lewis-Kelham, Edwin

    2015-01-01

    We propose a system for calculating the personalized annual fuel consumption and CO2 emissions from transportation. The system, named CO2NNIE, estimates the fuel consumption on the fastest route between the frequent destinations of the user. The travel time and fuel consumption estimated are based......% of the actual fuel consumption (4.6% deviation on average). We conclude, that the system provides new detailed information on CO2 emissions and fuel consumption for any make and model....

  14. Are there links between responses of soil microbes and ecosystem functioning to elevated CO2, N deposition and warming? A global perspective.

    Science.gov (United States)

    García-Palacios, Pablo; Vandegehuchte, Martijn L; Shaw, E Ashley; Dam, Marie; Post, Keith H; Ramirez, Kelly S; Sylvain, Zachary A; de Tomasel, Cecilia Milano; Wall, Diana H

    2015-04-01

    In recent years, there has been an increase in research to understand how global changes' impacts on soil biota translate into altered ecosystem functioning. However, results vary between global change effects, soil taxa, and ecosystem processes studied, and a synthesis of relationships is lacking. Therefore, here we initiate such a synthesis to assess whether the effect size of global change drivers (elevated CO2, N deposition, and warming) on soil microbial abundance is related with the effect size of these drivers on ecosystem functioning (plant biomass, soil C cycle, and soil N cycle) using meta-analysis and structural equation modeling. For N deposition and warming, the global change effect size on soil microbes was positively associated with the global change effect size on ecosystem functioning, and these relationships were consistent across taxa and ecosystem processes. However, for elevated CO2, such links were more taxon and ecosystem process specific. For example, fungal abundance responses to elevated CO2 were positively correlated with those of plant biomass but negatively with those of the N cycle. Our results go beyond previous assessments of the sensitivity of soil microbes and ecosystem processes to global change, and demonstrate the existence of general links between the responses of soil microbial abundance and ecosystem functioning. Further we identify critical areas for future research, specifically altered precipitation, soil fauna, soil community composition, and litter decomposition, that are need to better quantify the ecosystem consequences of global change impacts on soil biodiversity. © 2014 John Wiley & Sons Ltd.

  15. Forest succession at elevated CO2

    Energy Technology Data Exchange (ETDEWEB)

    Clark, James S.; Schlesinger, William H.

    2002-02-01

    We tested hypotheses concerning the response of forest succession to elevated CO2 in the FACTS-1 site at the Duke Forest. We quantified growth and survival of naturally recruited seedlings, tree saplings, vines, and shrubs under ambient and elevated CO2. We planted seeds and seedlings to augment sample sites. We augmented CO2 treatments with estimates of shade tolerance and nutrient limitation while controlling for soil and light effects to place CO2 treatments within the context of natural variability at the site. Results are now being analyzed and used to parameterize forest models of CO2 response.

  16. Reduced N cycling in response to elevated CO2, warming, and drought in a Danish heathland: Synthesizing results of the CLIMAITE project after two years of treatments

    DEFF Research Database (Denmark)

    Larsen, Klaus Steenberg; Andresen, Louise C.; Beier, Claus

    2011-01-01

    Field-scale experiments simulating realistic future climate scenarios are important tools for investigating the effects of current and future climate changes on ecosystem functioning and biogeochemical cycling. We exposed a seminatural Danish heathland ecosystem to elevated atmospheric carbon...... dioxide (CO2), warming, and extended summer drought in all combinations. Here, we report on the short-term responses of the nitrogen (N) cycle after 2 years of treatments. Elevated CO2 significantly affected aboveground stoichiometry by increasing the carbon to nitrogen (C/N) ratios in the leaves of both...... NH4+ consumption, gross mineralization, potential nitrification, denitrification and N2O emissions. Drought reduced belowground gross N mineralization and decreased fauna N mass and fauna N mineralization. Leaching was unaffected by treatments but was significantly higher across all treatments...

  17. Changes in Respiratory Mitochondrial Machinery and Cytochrome and Alternative Pathway Activities in Response to Energy Demand Underlie the Acclimation of Respiration to Elevated CO2 in the Invasive Opuntia ficus-indica1[OA

    Science.gov (United States)

    Gomez-Casanovas, Nuria; Blanc-Betes, Elena; Gonzalez-Meler, Miquel A.; Azcon-Bieto, Joaquim

    2007-01-01

    Studies on long-term effects of plants grown at elevated CO2 are scarce and mechanisms of such responses are largely unknown. To gain mechanistic understanding on respiratory acclimation to elevated CO2, the Crassulacean acid metabolism Mediterranean invasive Opuntia ficus-indica Miller was grown at various CO2 concentrations. Respiration rates, maximum activity of cytochrome c oxidase, and active mitochondrial number consistently decreased in plants grown at elevated CO2 during the 9 months of the study when compared to ambient plants. Plant growth at elevated CO2 also reduced cytochrome pathway activity, but increased the activity of the alternative pathway. Despite all these effects seen in plants grown at high CO2, the specific oxygen uptake rate per unit of active mitochondria was the same for plants grown at ambient and elevated CO2. Although decreases in photorespiration activity have been pointed out as a factor contributing to the long-term acclimation of plant respiration to growth at elevated CO2, the homeostatic maintenance of specific respiratory rate per unit of mitochondria in response to high CO2 suggests that photorespiratory activity may play a small role on the long-term acclimation of respiration to elevated CO2. However, despite growth enhancement and as a result of the inhibition in cytochrome pathway activity by elevated CO2, total mitochondrial ATP production was decreased by plant growth at elevated CO2 when compared to ambient-grown plants. Because plant growth at elevated CO2 increased biomass but reduced respiratory machinery, activity, and ATP yields while maintaining O2 consumption rates per unit of mitochondria, we suggest that acclimation to elevated CO2 results from physiological adjustment of respiration to tissue ATP demand, which may not be entirely driven by nitrogen metabolism as previously suggested. PMID:17660349

  18. Dorsomedial medullary 5-HT2 receptors mediate immediate onset of initial hyperventilation, airway dilation, and ventilatory decline during hypoxia in mice.

    Science.gov (United States)

    Kanamaru, Mitsuko; Homma, Ikuo

    2009-07-01

    The dorsomedial medulla oblongata (DMM) includes the solitary tract nucleus and the hypoglossal nucleus, to which 5-HT neurons project. Effects of 5-HT in the DMM on ventilatory augmentation and airway dilation are mediated via 5-HT2 receptors, which interact with the CO(2) drive. The interaction may elicit cycles between hyperventilation with airway dilation and hypoventilation with airway narrowing. In the present study, effects of 5-HT2 receptors in the DMM on hypoxic ventilatory and airway responses were investigated, while 5-HT release in the DMM was monitored. Adult male mice were anesthetized, and then a microdialysis probe was inserted into the DMM. The mice were placed in a double-chamber plethysmograph. After recovery from anesthesia, the mice were exposed to hypoxic gas (7% O(2) in N(2)) for 5 min with or without a 5-HT2 receptor antagonist (LY-53857) perfused in the DMM. 5-HT release in the DMM was increased by hypoxia regardless of the presence of LY-53857. Immediate onset and the peak of initial hypoxic hyperventilatory responses were delayed. Subsequent ventilatory decline and airway dilation during initial hypoxic hyperventilation were suppressed with LY-53857. These results suggest that 5-HT release increased by hypoxia acts on 5-HT2 receptors in the DMM, which contributes to the immediate onset of initial hypoxic hyperventilation, airway dilation, and subsequent ventilatory decline. Hypoxic ventilatory and airway responses mediated via 5-HT2 receptors in the DMM may play roles in immediate rescue and defensive adaptation for hypoxia and may be included in periodic breathing and the pathogenesis of obstructive sleep apnea.

  19. Breathing pattern and ventilatory control in chronic tetraplegia.

    Science.gov (United States)

    Spungen, Ann M; Bauman, William A; Lesser, Marvin; McCool, F Dennis

    2009-01-01

    Blunted ventilatory responses to carbon dioxide indicate that respiratory control is impaired when ventilation is stimulated in individuals with tetraplegia; however, respiratory control during resting breathing has not been extensively studied in this population. Our objective was to evaluate respiratory control and sigh frequency during resting breathing in persons with tetraplegia. A prospective, two-group comparative study was performed. Breathing pattern was assessed in ten outpatients with chronic tetraplegia and eight age- and gender-matched able-bodied controls. Subjects were noninvasively monitored for 1 h, while seated and at rest. Tidal volume (V(T)) was calculated from the sum of the anteroposterior displacements of the rib cage and abdomen and the axial displacement of the chest wall. Inspiratory time (T(I)), V(T), and the ratio of V(T) to inspiratory time (V(T)/T(I)) were calculated breath by breath. A sigh was defined as any breath greater than two or more times an individual's mean V(T). Minute ventilation, V(T)/T(I), and sigh frequency were reduced in tetraplegia compared with controls (5.24 +/- 1.15 vs. 7.16 +/- 1.29 L/min, P tetraplegia: R = 0.88; P = 0.001 and control: R = 0.70; P tetraplegia. These findings extend prior observations of disordered respiratory control during breathing stimulated by CO(2) in tetraplegia to resting breathing.

  20. Differential responses of calcifying and non-calcifying epibionts of a brown macroalga to present-day and future upwelling pCO2.

    Directory of Open Access Journals (Sweden)

    Vincent Saderne

    Full Text Available Seaweeds are key species of the Baltic Sea benthic ecosystems. They are the substratum of numerous fouling epibionts like bryozoans and tubeworms. Several of these epibionts bear calcified structures and could be impacted by the high pCO2 events of the late summer upwellings in the Baltic nearshores. Those events are expected to increase in strength and duration with global change and ocean acidification. If calcifying epibionts are impacted by transient acidification as driven by upwelling events, their increasing prevalence could cause a shift of the fouling communities toward fleshy species. The aim of the present study was to test the sensitivity of selected seaweed macrofoulers to transient elevation of pCO2 in their natural microenvironment, i.e. the boundary layer covering the thallus surface of brown seaweeds. Fragments of the macroalga Fucus serratus bearing an epibiotic community composed of the calcifiers Spirorbis spirorbis (Annelida and Electra pilosa (Bryozoa and the non-calcifier Alcyonidium hirsutum (Bryozoa were maintained for 30 days under three pCO2 conditions: natural 460 ± 59 µatm, present-day upwelling1193 ± 166 µatm and future upwelling 3150 ± 446 µatm. Only the highest pCO2 caused a significant reduction of growth rates and settlement of S. spirorbis individuals. Additionally, S. spirorbis settled juveniles exhibited enhanced calcification of 40% during daylight hours compared to dark hours, possibly reflecting a day-night alternation of an acidification-modulating effect by algal photosynthesis as opposed to an acidification-enhancing effect of algal respiration. E. pilosa colonies showed significantly increased growth rates at intermediate pCO2 (1193 µatm but no response to higher pCO2. No effect of acidification on A. hirsutum colonies growth rates was observed. The results suggest a remarkable resistance of the algal macro-epibionts to levels of acidification occurring at present day upwellings in the Baltic

  1. Does the growth response of woody plants to elevated CO2 increase with temperature? A model-oriented meta-analysis.

    Science.gov (United States)

    Baig, Sofia; Medlyn, Belinda E; Mercado, Lina M; Zaehle, Sönke

    2015-12-01

    The temperature dependence of the reaction kinetics of the Rubisco enzyme implies that, at the level of a chloroplast, the response of photosynthesis to rising atmospheric CO2 concentration (Ca ) will increase with increasing air temperature. Vegetation models incorporating this interaction predict that the response of net primary productivity (NPP) to elevated CO2 (eCa ) will increase with rising temperature and will be substantially larger in warm tropical forests than in cold boreal forests. We tested these model predictions against evidence from eCa experiments by carrying out two meta-analyses. Firstly, we tested for an interaction effect on growth responses in factorial eCa  × temperature experiments. This analysis showed a positive, but nonsignificant interaction effect (95% CI for above-ground biomass response = -0.8, 18.0%) between eCa and temperature. Secondly, we tested field-based eCa experiments on woody plants across the globe for a relationship between the eCa effect on plant biomass and mean annual temperature (MAT). This second analysis showed a positive but nonsignificant correlation between the eCa response and MAT. The magnitude of the interactions between CO2 and temperature found in both meta-analyses were consistent with model predictions, even though both analyses gave nonsignificant results. Thus, we conclude that it is not possible to distinguish between the competing hypotheses of no interaction vs. an interaction based on Rubisco kinetics from the available experimental database. Experiments in a wider range of temperature zones are required. Until such experimental data are available, model predictions should aim to incorporate uncertainty about this interaction. © 2015 John Wiley & Sons Ltd.

  2. Improved Understanding of the Photosynthetic Response of Seven Rice Genotypes with Different Drought Sensitivity using Light and CO2 Response Curves

    Science.gov (United States)

    Mitra, B.; Basu, S.; Bereznyakov, D.; Pereira, A.; Naithani, K. J.

    2015-12-01

    Drought across different agro-climatic regions of the world has the capacity to drastically impact the yield potential of rice. Consequently, there is growing interest in developing drought tolerant rice varieties with high yield. We parameterized two photosynthesis models based on light and CO2 response curves for seven different rice genotypes with different drought survival mechanisms: sensitive (Nipponbar, TEJ), resistance (Bengal, TRJ), avoidance by osmotic adjustment (Kaybonnet, TRJ; IRAT177, TRJ; N22, Aus; Vandana, Aus; and O Glabberrima, 316603). All rice genotypes were grown in greenhouse conditions (24 °C ± 3°C air temperature and ~ 600 μmol m-2 s-1 light intensity) with light/dark cycles of 10/14 h in water filled trays simulating flooded conditions. Measurements were conducted on fully grown plants (35 - 60 days old) under simulated flooded and drought conditions. Preliminary results have shown that the drought sensitive genotype, Nipponbare has the lowest photosynthetic carboxylation capacity (Vcmax) and a similar electron transport rate (Jmax) compared to the drought resistant genotype IRAT 177. Mitochondrial respiration (Rd) of all the genotypes were similar while quantum yield of the drought sensitive genotype was greater than that of the drought resistant genotypes. While both drought tolerant and drought sensitive rice genotypes have the same photosynthetic yield, from an irrigation perspective the former would require less 'drop per grain'. This has enormous economic and management implications on account of dwindling water resources across the world due to drought.

  3. CO2 laser resurfacing.

    Science.gov (United States)

    Fitzpatrick, R E

    2001-07-01

    The CO2 Laser offers a variety of unique features in resurfacing facial photodamage and acne scarring. These include hemostasis, efficient removal of the epidermis in a single pass, thermally induced tissue tightening, and safe, predictable tissue interaction. Knowledge of these mechanisms will result in the capability of using the CO2 laser effectively and safely whether the goal is superficial or deep treatment.

  4. CO2 uit buitenlucht

    NARCIS (Netherlands)

    Weel, van P.A.; Vanthoor, B.H.E.

    2016-01-01

    The supply of additional CO2 in a greenhouse will be restricted in the future. The concentration in outside air has risen above 400 ppm. This may open the possibility to blow this air through the canopy to increase growth. In this project, the vertical CO2 concentration was measured in a vertical

  5. Response of photosynthetic characters to CO2 change on C3 and C4 cereal crops grown in Lunar Palace 1

    Science.gov (United States)

    Wang, Minjuan; Liu, Hong; Fu, Yuming; Shao, Lingzhi; Dong, Chen; Liu, Guanghui

    Lunar Palace 1, as an integrative experiment facility for Permanent Astrobase Life-support Artificial Closed Ecosystem (P.A.L.A.C.E.), provides a largely closed environment for crop growth tests for Bioregenerative Life Support System (BLSS). In this study, we evaluated the response of photosynthetic characters of two soybean cultivars (Glycine max (L.) Merr., ‘Zhonghuang13’and ‘Heihe35’) of C _{3} plants and one maize ( Zea mays L.) of C _{4} plants, which were selected as candidates for cultivation in BLSS. Plants were cultivated in stainless steel pots equipped with the porous-tube nutrient delivery system (PTNDS) and grew under controlled environmental conditions of Lunar Palace 1 (12 h photoperiod, light intensity 500 umol m (-2) s (-1) , temperature regime 26/22 (o) C light/dark). Fertigation was performed with a standard Hoagland solution, in which pH was kept at 5.8. A gas exchange/chlorophyII fluorescence analysis was performed to determine their net photosynthesis (Pn), stomatal (g _{s}) and mesophyll (g _{m}) conductances, intercellular CO _{2} concentration (Ci), and transpiration rate (E) under different elevated CO _{2} concentration. In order to partially describe how leaf physiology responds to the elevated CO _{2}, Chl content and the activity and amount of rubisco were analyzed. This study provides a theoretical basis for the crop selection in BLSS.

  6. A comparative approach for modeling of CO2 storage capacity and associated pressure response - analysis of data from South Scania site, Sweden

    Science.gov (United States)

    Tian, Liang; Yang, Zhibing; Jung, Byeongju; Joodaki, Saba; Niemi, Auli; Fagerlund, Fritjof; Erlström, Mikael

    2014-05-01

    Comprehensive modeling with models of varying level of accuracy can give valuable information for the appraisal of CO2 storage potential and the assessment of risks for a given site. Here, we present a comparative modeling approach/workflow where a sequence of mathematical models of different levels of complexity are applied. These models span from semi-analytical solution to three-dimensional (3D) numerical simulator. The Scania Site, southwest Sweden where the geological model was developed within the MUSTANG project activities is selected for an example study. Initially, a semi-analytical approach is used to investigate pressure increase induced by CO2 injection so as to determine a viable injection strategy (including injection rate and number of injection wells) and parameter sensitivity. The result is then used as a starting point in subsequent numerical simulations with TOUGH2/ECO2N for 2D and 3D simulations. At the same time a simplified numerical model with the vertical equilibrium (VE) approach is also implemented. A systematic comparison is done between the different methods in terms of pressure response. CO2 spreading during both the injection and post-injection phase is also carefully compared between the 2D, VE and 3D numerical simulations. Through these comparisons we can thus identify a model with the appropriate level of complexity according to the objectives of the modeling study. Given the data available, we show an effective modeling strategy in achieving order-of-magnitude estimates on the behavior of the identified CO2 traps during and after the injection.

  7. Rapid responses of mesophyll conductance to changes of CO2 concentration, temperature and irradiance are affected by N supplements in rice.

    Science.gov (United States)

    Xiong, Dongliang; Liu, Xi; Liu, Limin; Douthe, Cyril; Li, Yong; Peng, Shaobing; Huang, Jianliang

    2015-12-01

    Photosynthesis in C3 plants is significantly limited by mesophyll conductance (gm ), which can vary with leaf anatomical traits and nitrogen (N) supplements. Several studies have investigated the response of gm to N supplements; however, none examined the implications of N supplements on the response of gm to rapid environmental changes. Here we investigated the effect of N supplement on gm and the response of gm to change of CO2 , temperature and irradiance in rice. High N supplement (HN) increased mesophyll cell wall surface area and chloroplast surface area exposed to intercellular airspace per leaf area, and reduced cell wall thickness. These changes resulted in increased gm . The gm of leaves with HN was more sensitive to changes in CO2 concentration, temperature and irradiance. The difference in leaf structural features between low N supplement and HN indicates that a rapid change in gm is related to the regulation of diffusion through biological membranes rather than leaf structural features. These results will contribute to an understanding of the determinants of gm response to rapid changes in environmental factors. © 2015 John Wiley & Sons Ltd.

  8. The temperature response of CO2 assimilation, photochemical activities and Rubisco activation in Camelina sativa, a potential bioenergy crop with limited capacity for acclimation to heat stress.

    Science.gov (United States)

    Carmo-Silva, A Elizabete; Salvucci, Michael E

    2012-11-01

    The temperature optimum of photosynthesis coincides with the average daytime temperature in a species' native environment. Moderate heat stress occurs when temperatures exceed the optimum, inhibiting photosynthesis and decreasing productivity. In the present study, the temperature response of photosynthesis and the potential for heat acclimation was evaluated for Camelina sativa, a bioenergy crop. The temperature optimum of net CO(2) assimilation rate (A) under atmospheric conditions was 30-32 °C and was only slightly higher under non-photorespiratory conditions. The activation state of Rubisco was closely correlated with A at supra-optimal temperatures, exhibiting a parallel decrease with increasing leaf temperature. At both control and elevated temperatures, the modeled response of A to intercellular CO(2) concentration was consistent with Rubisco limiting A at ambient CO(2). Rubisco activation and photochemical activities were affected by moderate heat stress at lower temperatures in camelina than in the warm-adapted species cotton and tobacco. Growth under conditions that imposed a daily interval of moderate heat stress caused a 63 % reduction in camelina seed yield. Levels of cpn60 protein were elevated under the higher growth temperature, but acclimation of photosynthesis was minimal. Inactivation of Rubisco in camelina at temperatures above 35 °C was consistent with the temperature response of Rubisco activase activity and indicated that Rubisco activase was a prime target of inhibition by moderate heat stress in camelina. That photosynthesis exhibited no acclimation to moderate heat stress will likely impact the development of camelina and other cool season Brassicaceae as sources of bioenergy in a warmer world.

  9. Isotopic and nutritional evidence for species- and site-specific responses to N deposition and elevated CO2 in temperate forests

    Science.gov (United States)

    Silva, Lucas C. R.; Gómez-Guerrero, Armando; Doane, Timothy A.; Horwath, William R.

    2015-06-01

    In this study we show that the effect of rising atmospheric CO2 levels on forest productivity is influenced by changes in nutrient availability caused by nitrogen (N) deposition. We used a dual-isotope approach (δ15N and δ13C), combined with dendrochronological and nutritional analyses, to evaluate the response of two dominant tree species in natural forest ecosystems near Mexico City (Pinus hartwegii—pine; Abies religiosa—fir). Our analysis focuses on changes that occurred over the past 50 years at two sites, one under high and one under low N deposition rates. Analyses of carbon isotope composition indicate increasing water-use efficiency in response to rising CO2 levels for both species and sites but this effect did not lead to improved tree growth. The magnitude and direction of shifts in 13C discrimination indicate a process of acclimation that varied with the rate of N deposition and species traits. Since the 1960s, strong negative responses to N deposition have been observed in fir trees, which showed altered foliar nutrition and growth decline, while the negative impacts of N deposition on pine trees remained undetectable until the 1990s. In recent years, both species have shown significant growth decline under high N deposition despite increasing atmospheric CO2. Multivariate analysis of leaf nutrients indicates that growth decline was prompted by depleted soil macronutrient (P, K, and Ca) and micronutrient (Cu, Fe, Zn, and Mn) availability. At both sites, fir trees were a better indicator of N deposition due to differences in canopy rainfall interception.

  10. In situ developmental responses of tropical sea urchin larvae to ocean acidification conditions at naturally elevated pCO2 vent sites.

    Science.gov (United States)

    Lamare, Miles D; Liddy, Michelle; Uthicke, Sven

    2016-11-30

    Laboratory experiments suggest that calcifying developmental stages of marine invertebrates may be the most ocean acidification (OA)-sensitive life-history stage and represent a life-history bottleneck. To better extrapolate laboratory findings to future OA conditions, developmental responses in sea urchin embryos/larvae were compared under ecologically relevant in situ exposures on vent-elevated pCO 2 and ambient pCO 2 coral reefs in Papua New Guinea. Echinometra embryos/larvae were reared in meshed chambers moored in arrays on either venting reefs or adjacent non-vent reefs. After 24 and 48 h, larval development and morphology were quantified. Compared with controls (mean pH (T) = 7.89-7.92), larvae developing in elevated pCO 2 vent conditions (pH (T) = 7.50-7.72) displayed a significant reduction in size and increased abnormality, with a significant correlation of seawater pH with both larval size and larval asymmetry across all experiments. Reciprocal transplants (embryos from vent adults transplanted to control conditions, and vice versa) were also undertaken to identify if adult acclimatization can translate resilience to offspring (i.e. transgenerational processes). Embryos originating from vent adults were, however, no more tolerant to reduced pH. Sea temperature and chlorophyll-a concentrations (i.e. larval nutrition) did not contribute to difference in larval size, but abnormality was correlated with chlorophyll levels. This study is the first to examine the response of marine larvae to OA scenarios in the natural environment where, importantly, we found that stunted and abnormal development observed in situ are consistent with laboratory observations reported in sea urchins, in both the direction and magnitude of the response. © 2016 The Author(s).

  11. Response of CO2 and H2O fluxes in a mountainous tropical rainforest in equatorial Indonesia to El Niño events

    DEFF Research Database (Denmark)

    Olchev, A.; Ibrom, Andreas; Panferov, O.

    2015-01-01

    The possible impact of El Niño–Southern Oscillation (ENSO) events on the main components of CO2 and H2O fluxes in a pristine mountainous tropical rainforest growing in Central Sulawesi in Indonesia is described. The fluxes were continuously measured using the eddy covariance method for the period...... exchange showed a very high sensitivity of Evapotranspiration (ET) and Gross Primary Production (GPP) of the tropical rain forest to meteorological variations caused by both El Niño and La Niña episodes. Incoming solar radiation is the main governing factor that is responsible for ET and GPP variability...

  12. Temperature and CO2 dependency of the photosynthetic photon flux density responses of leaves of Vitis vinifera cvs. Chardonnay and Merlot grown in a hot climate.

    Science.gov (United States)

    Greer, Dennis H

    2017-02-01

    Comparisons of the photosynthetic responses to light and temperature between related cultivars are important to understand how well matched they are to the climate where they are grown. Photosynthetic light responses at a range of leaf temperatures and two CO2 concentrations were measured on leaves of two grapevine cultivars (Vitis vinifera L.) Chardonnay and Merlot vines growing in field conditions. The objective was to assess the interaction between photon flux density (PFD), leaf temperature and CO2 on photosynthesis and to compare the two cultivars. Merlot leaves maintained higher light-saturated rates of photosynthesis at all leaf temperatures compared with the Chardonnay leaves. At low temperatures, a reduced photon yield offset with a high stomatal conductance accounted for the low rates of the Chardonnay leaves. At moderate to high temperatures, photon yields, PFDs at light saturation and stomatal conductances did not account for differences between Merlot and Chardonnay leaves. At elevated CO2 (800 μmol mol-1) concentrations, the differences in photosynthetic performance between the cultivars were enhanced, with 30% higher light saturated rates for Merlot compared with Chardonnay leaves. Merlot berries accumulated more sugar, consistent with published data. These results demonstrate Chardonnay, unlike Merlot, appeared to be poorly matched to the hot climate. However, considering the current market and political trends, low alcoholic wines (and, thus, low sugar grapes) should be preferred. Especially in hot climates, it is always hard to obtain such kind of wines and, thus, the most interesting agronomical challenge, especially for Chardonnay vines could be interpreted in an opposite way. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  13. Intracellular pH and its response to CO2-driven seawater acidification in symbiotic versus non-symbiotic coral cells.

    Science.gov (United States)

    Gibbin, Emma M; Putnam, Hollie M; Davy, Simon K; Gates, Ruth D

    2014-06-01

    Regulating intracellular pH (pHi) is critical for optimising the metabolic activity of corals, yet the mechanisms involved in pH regulation and the buffering capacity within coral cells are not well understood. Our study investigated how the presence of symbiotic dinoflagellates affects the response of pHi to PCO2-driven seawater acidification in cells isolated from Pocillopora damicornis. Using the fluorescent dye BCECF-AM, in conjunction with confocal microscopy, we simultaneously characterised the pHi response in host coral cells and their dinoflagellate symbionts, in symbiotic and non-symbiotic states under saturating light, with and without the photosynthetic inhibitor DCMU. Each treatment was run under control (pH 7.8) and CO2-acidified seawater conditions (decreasing pH from 7.8 to 6.8). After 105 min of CO2 addition, by which time the external pH (pHe) had declined to 6.8, the dinoflagellate symbionts had increased their pHi by 0.5 pH units above control levels when in the absence of DCMU. In contrast, in both symbiotic and non-symbiotic host coral cells, 15 min of CO2 addition (0.2 pH unit drop in pHe) led to cytoplasmic acidosis equivalent to 0.3-0.4 pH units irrespective of whether DCMU was present. Despite further seawater acidification over the duration of the experiment, the pHi of non-symbiotic coral cells did not change, though in host cells containing a symbiont cell the pHi recovered to control levels when photsynthesis was not inhibited. This recovery was negated when cells were incubated with DCMU. Our results reveal that photosynthetic activity of the endosymbiont is tightly coupled with the ability of the host cell to recover from cellular acidosis after exposure to high CO2/low pH. © 2014. Published by The Company of Biologists Ltd.

  14. Initial Response of the Nitrogen Cycle to Soil Warming and Elevated CO2 in Northern Minnesota Peatlands

    Science.gov (United States)

    Peatlands store 30% of global soil carbon. Many of these peatlands are located in boreal regions which are expected to have the highest temperature increases in response to climate change. As climate warms, peat decomposition may accelerate and release greenhouse gases. Spruce an...

  15. Can current moisture responses predict soil CO2 efflux under altered precipitation regimes? A synthesis of manipulation experiments

    DEFF Research Database (Denmark)

    Vicca, S.; Bahn, M.; Estiarte, M.

    2014-01-01

    dependencies of SCE. Hence, the most justified answer to the question of whether current moisture responses of SCE can be extrapolated to predict SCE under altered precipitation regimes is 'no' - as based on the most reliable data sets available. We strongly recommend that future experiments focus more...

  16. Data-Constrained Projections of Methane Fluxes in a Northern Minnesota Peatland in Response to Elevated CO2 and Warming

    Science.gov (United States)

    Shuang Ma; Jiang Jiang; Yuanyuan Huang; Zheng Shi; Rachel M. Wilson; Daniel Ricciuto; Stephen D. Sebestyen; Paul J. Hanson; Yiqi Luo

    2017-01-01

    Large uncertainties exist in predicting responses of wetland methane (CH4) fluxes to future climate change. However, sources of the uncertainty have not been clearly identified despite the fact that methane production and emission processes have been extensively explored. In this study, we took advantage of manual CH4 flux...

  17. Simple additive effects are rare: a quantitative review of plant biomass and soil process responses to combined manipulations of CO2 and temperature

    NARCIS (Netherlands)

    Dieleman, W.; Vicca, S.; Dijkstra, F.A.; Hoosbeek, M.R.

    2012-01-01

    In recent years, increased awareness of the potential interactions between rising atmospheric CO2 concentrations ([ CO2 ]) and temperature has illustrated the importance of multifactorial ecosystem manipulation experiments for validating Earth System models. To address the urgent need for increased

  18. Nonstructural carbohydrate-balance response to long-term elevated CO2 exposure in European beech and Norway spruce mixed cultures: biochemical and ultrastructural responses

    Czech Academy of Sciences Publication Activity Database

    Mašková, P.; Radochová, Barbora; Lhotáková, Z.; Michálek, Jan; Lipavská, H.

    2017-01-01

    Roč. 47, č. 11 (2017), s. 1498-1494 ISSN 0045-5067 R&D Projects: GA ČR(CZ) GAP501/10/0340 Institutional support: RVO:67985823 Keywords : chloroplast ultrastructure * CO2 enrichment * forest trees * soluble carbohydrates * starch Subject RIV: GK - Forestry Impact factor: 1.827, year: 2016

  19. Ventilatory function during exercise in multiple sclerosis and impact of training intervention: cross-sectional and randomized controlled trial.

    Science.gov (United States)

    Hansen, D; Wens, I; Keytsman, C; Verboven, K; Dendale, P; Eijnde, B O

    2015-10-01

    Patients with MS (pwMS) often experience resting ventilatory anomalies. Ventilatory function during exercise and impact of long-term training intervention remains however uncertain. The aim of this study was to examine the ventilatory function during exercise and impact of a 6-month training intervention in pwMS. Combination of a cross-sectional (part 1) and randomized controlled trial (part 2). University rehabilitation facility. Caucasian patients with MS and healthy controls. In part 1, the ventilatory function during submaximal endurance exercise was compared between pwMS (N.=37) and healthy participants (N.=15). In part 2, pwMS were then randomly assigned to a 6-month training intervention (N.=16) or usual care (N.=11). Following training intervention, ventilatory function during exercise was re-evaluated. Despite comparable relative exercise testing intensities between groups in part 1, significantly elevated steady-state exercise dead space/tidal volume ratio, O2 uptake and CO2 output equivalent, end-tidal O2 pressure, ratings of perceived exertion and lowered end-tidal CO2 pressure and O2 pulse was observed in pwMS (Ptraining intervention, ventilatory dysfunction remained present during endurance exercise (P>0.05). Patients with MS experience a ventilatory dysfunction during endurance exercise, which is related to worse exercise tolerance. This ventilatory anomaly remains present after long-term training intervention. Patients with MS experience ventilatory dysfunction during exercise. This dysfunction is related to exercise tolerance and ratings of perceived exertion. Long-term exercise training did not remediate this ventilatory dysfunction. The systematic examination of the pulmonary/cardiovascular system at rest and during exercise is recommended in MS.

  20. Fluxes of CO2 and CH4 in high latitude wetlands: measuring, modelling and predicting response to climate change

    OpenAIRE

    Panikov, Nicolai S.

    1999-01-01

    This review covers selected aspects of recent international efforts to measure and model greenhouse gas emission from northern wetlands, to identify the environmental factors that control gas emission, and to investigate wetlands’responses (particularly with respect to gas emission) to global change. Both bottom-up and top-to-bottom approaches, based respectively on local observations plus inventory of gas fluxes and inverse modelling of global circulation, agree on the size of the high latit...

  1. The optimization of essential oils supercritical CO2 extraction from Lavandula hybrida through static-dynamic steps procedure and semi-continuous technique using response surface method.

    Science.gov (United States)

    Kamali, Hossein; Aminimoghadamfarouj, Noushin; Golmakani, Ebrahim; Nematollahi, Alireza

    2015-01-01

    The aim of this study was to examine and evaluate crucial variables in essential oils extraction process from Lavandula hybrida through static-dynamic and semi-continuous techniques using response surface method. Essential oil components were extracted from Lavandula hybrida (Lavandin) flowers using supercritical carbon dioxide via static-dynamic steps (SDS) procedure, and semi-continuous (SC) technique. Using response surface method the optimum extraction yield (4.768%) was obtained via SDS at 108.7 bar, 48.5°C, 120 min (static: 8×15), 24 min (dynamic: 8×3 min) in contrast to the 4.620% extraction yield for the SC at 111.6 bar, 49.2°C, 14 min (static), 121.1 min (dynamic). The results indicated that a substantial reduction (81.56%) solvent usage (kg CO2/g oil) is observed in the SDS method versus the conventional SC method.

  2. Ventilatory anaerobic thresholds of individuals recovering from traumatic brain injury compared with noninjured controls.

    Science.gov (United States)

    Amonette, William E; Mossberg, Kurt A

    2013-01-01

    The purpose of this study was to compare the peak aerobic capacities and ventilatory anaerobic thresholds (VAT) of individuals with a traumatic brain injury (TBI) to age- and gender-matched controls. Nineteen participants that previously suffered a mild to moderate TBI and 19 apparently healthy controls volunteered as subjects. Traumatic brain injury and healthy controls were matched for age and gender and were similar in weight and body mass index. Volunteers performed a maximal graded treadmill test to volitional failure where oxygen consumption ((Equation is included in full-text article.)O2), carbon dioxide production ((Equation is included in full-text article.)CO2, ventilation ((Equation is included in full-text article.)E, and heart rate were measured continuously. From metabolic and ventilatory data, VAT was measured using a previously described method. VAT and peak exercise responses of participants with a TBI were compared with healthy controls. The (Equation is included in full-text article.)O2, and (Equation is included in full-text article.)CO2 at VAT and peak exercise were lower for TBI compared with healthy controls. (Equation is included in full-text article.)E was also lower for TBI at VAT and peak exercise. Heart rate was lower for TBI at VAT; however, TBI had similar heart rate to healthy controls at peak exercise. The VAT and peak exercise capacities of participants with a TBI were below the metabolic demands of many routine daily activities. The data suggest that therapeutic interventions for individuals with a TBI should include targeted exercise prescriptions to improve cardiorespiratory fitness.

  3. Respuesta ventilatoria al ejercicio post-entrenamiento de miembros superiores en la enfermedad pulmonar obstructiva crónica Ventilatory response to upper limb exercise after training in COPD

    Directory of Open Access Journals (Sweden)

    Martín Sívori

    2013-02-01

    Full Text Available Está poco estudiada la modificación de la respuesta ventilatoria al ejercicio de miembros superiores (MS post-entrenamiento en la EPOC. Se realizó un estudio prospectivo, aleatorio y controlado en pacientes con EPOC, entrenando un grupo los miembros inferiores (GC y otro adicionalmente los MS (GM. Se comparó la respuesta ventilatoria al ejercicio de MS pre y post-entrenamiento. Se estudiaron 43 pacientes, 84% varones, estadio GOLD II (moderado 6 (14%, GOLD III (grave 15 (35% y GOLD IV (muy grave 22 (51%. Veintiocho pacientes completaron el estudio. Post-entrenamiento: se observó en el grupo GM (N = 14 incrementos del V T isotiempo (p There are scarce studies evaluating the modification of ventilatory response to upper limb exercise (ULE post-training in COPD patients. A prospective, randomized, controlled study was performed comparing two groups: training lower limbs (LL, vs. LL plus upper limb training (UL, in relation to their pre and post-training ventilatory response to ULE. A total of 43 COPD patients were included; 84% male, 6 (14% GOLD moderate stage (II, 15 (35% severe stage (III, and 22 (51% very severe (IV; 28 patients completed the study. After ULE, in UL group (N = 14 a training increased isotime VT (p < 0.0001 was observed, as well as an increase in the inspiratory capacity isotime percentage (IC, 8.8%, p = 0.001, in the Ti isotime (29.3%, p = 0.022 and in the Ti/Tot isotime (37.4%, p = 0.0004. Also, Te isotime was reduced (26%, p = 0.009 and IC isotime was increased (p = 0.01 after ULE. In LL group (N = 14, training increased VT/Ti isotime (66.86%, p = 0.0005 after ULE. Also, after ULE a decrease in Ti isotime (27.9%, p = 0.015 and in Ti/Tot isotime (22.74%, p = 0.00016 were observed. A moderate correlation was observed between Δ respiratory rate and ΔIC after ULE, only for post-training in UL group (r = -0.53 , p < 0.001. Comparing both groups in relation to their responses to ULE, only in the UL group was a reduction

  4. A combination of CO2 laser and plasma surface modification of poly(etheretherketone) to enhance osteoblast response

    Science.gov (United States)

    Zheng, Yanyan; Xiong, Chengdong; Wang, Zhecun; Li, Xiaoyu; Zhang, Lifang

    2015-07-01

    Poly(etheretherketone) (PEEK) is a rigid semicrystalline polymer that combines excellent mechanical properties, broad chemical resistance and bone-like stiffness and is widely used in biomedical fields. However, the bio-inert surface of PEEK tends to hinder its biomedical applications when direct osteointegration between the implants and the host tissue is desired. In this work, we demonstrate a dual modification method, which combines the laser and plasma surface treatment to combine advantages of both chemical states and microstructures for osteoblasts responses. While the plasma treatment introduces surface carboxyl groups (sbnd COOH) onto PEEK surface, the laser treatment constructs microstructures over the PEEK surface. Our results indicated that sbnd COOH as well as microgrooves containing micropores or microcraters structure are constructed on PEEK surface and plasma treatment has no apparent effect on the morphology of microstructures produced by laser micromachining. Unexpectedly, the superior mechanical properties of PEEK were maintained irrespective of the treatment used. Compared to native PEEK and single treated PEEK, dual modified PEEK is more favorable for pre-osteoblasts (MC3T3-E1) adhesion, spreading and proliferation. Moreover, cell pseudopodia protrude into the micropores or microcraters, in favor of forming firmer bone-implant integration. Our study illustrates enhanced osteoblasts responses to dual treated PEEK surface, which gives beneficial information of its potential use in orthopedic or dental implants.

  5. Capnography: monitoring CO2.

    Science.gov (United States)

    Casey, Georgina

    2015-10-01

    MONITORING RESPIRATORY and metabolic function by using capnography to measure end tidal carbon dioxide is standard practice in anaesthesia. It is also becoming more common in intensive care units and during procedural sedation. End tidal carbon dioxide (EtCO2) monitoring may also be used to assess effectiveness of cardiopulmonary resuscitation. Capnography is now emerging in general medical and surgical wards to monitor respiratory depression in patients using opioid analgesics. Using EtCO2 to monitor respiratory function offers many benefits over pulse oximetry. It is important to understand the differences between these two monitoring methods, and why capnography is increasingly favoured in many situations. An understanding of the physiological processes involved in CO2 excretion allows nurses to use capnography in a safe and meaningful way, while monitoring at-risk patients in acute care.

  6. CO2-strategier

    DEFF Research Database (Denmark)

    Jørgensen, Michael Søgaard

    2008-01-01

    I 2007 henvendte Lyngby-Taarbæk kommunens Agenda 21 koordinator sig til Videnskabsbutikken og spurgte om der var interesse for at samarbejde om CO2-strategier. Da Videnskabsbutikken DTU er en åben dør til DTU for borgerne og deres organisationer, foreslog Videnskabsbutikken DTU at Danmarks...... Naturfredningsforening’s lokalkomité for Lyngby blev en del af samarbejdet for at få borgerne i kommunen involveret i arbejdet med at udvikle strategier for reduktion af CO2. Siden sommeren 2007 har Videnskabsbutikken DTU, Lyngby-Taarbæk kommune og Danmarks Naturfredningsforening i Lyngby-Taarbæk samarbejdet om analyse...... og innovation i forhold til CO2-strategier....

  7. CO2 cycle

    Science.gov (United States)

    Titus, Timothy N.; Byrne, Shane; Colaprete, Anthony; Forget, Francois; Michaels, Timothy I.; Prettyman, Thomas H.

    2017-01-01

    This chapter discusses the use of models, observations, and laboratory experiments to understand the cycling of CO2 between the atmosphere and seasonal Martian polar caps. This cycle is primarily controlled by the polar heat budget, and thus the emphasis here is on its components, including solar and infrared radiation, the effect of clouds (water- and CO2-ice), atmospheric transport, and subsurface heat conduction. There is a discussion about cap properties including growth and regression rates, albedos and emissivities, grain sizes and dust and/or water-ice contamination, and curious features like cold gas jets and araneiform (spider-shaped) terrain. The nature of the residual south polar cap is discussed as well as its long-term stability and ability to buffer atmospheric pressures. There is also a discussion of the consequences of the CO2 cycle as revealed by the non-condensable gas enrichment observed by Odyssey and modeled by various groups.

  8. Components to the acid-base related ventilatory drives in the South American lungfish Lepidosiren paradoxa.

    Science.gov (United States)

    Amin-Naves, J; Giusti, H; Hoffmann, A; Glass, M L

    2007-01-15

    Lungfish are closely related to terrestrial vertebrates (tetrapoda). Like tetrapods, the South American lungfish (Lepidosiren paradoxa) has central chemoreceptors involved in regulation of acid-base status. However, no data were available on peripheral CO(2)/[H(+)] receptors. Therefore, we tested the hypothesis that such receptors exist by measuring the ventilatory responses during a 5h exposure to combined aquatic/gas phase hypercarbia 7% (approximately 49 mmHg). Normocarbic control ventilation was 22 ml BTPS kg(-1)h(-1), and hypercarbia increased ventilation to 175 ml BTPS kg(-1)h(-1) at 5h. This procedure was repeated with the modification that normocarbic mock CSF (pH 7.45; P(CO2) = 20.7 mmHg) was applied to superfuse the cerebral ventricular system during the last 2h of the experiment. This served to eliminate the hypercarbic stimulus to the central chemoreceptors, while possible responses from peripheral chemoreceptors would remain intact. Peripheral receptors were detected, since ventilation became reduced to 62 ml BTPS kg(-1)h(-1) (P<0.05), which exceeds the initial normocarbic control ventilation (P<0.05). Based on this, the peripheral contribution accounted for 20% of the total response to hypercarbia, similar to the contribution of these receptors in man.

  9. Final Technical Report: Response of Mediterranean-Type Ecosystems to Elevated Atmospheric CO2 and Associated Climate Change

    Energy Technology Data Exchange (ETDEWEB)

    Oechel, Walter C

    2002-08-15

    This research incorporated an integrated hierarchical approach in space, time, and levels of biological/ecological organization to help understand and predict ecosystem response to elevated CO{sub 2} and concomitant environmental change. The research utilized a number of different approaches, and collaboration of both PER and non-PER investigators to arrive at a comprehensive, integrative understanding. Central to the work were the CO{sub 2}-controlled, ambient Lit, Temperature controlled (CO{sub 2}LT) null-balance chambers originally developed in the arctic tundra, which were re-engineered for the chaparral with treatment CO{sub 2} concentrations of from 250 to 750 ppm CO{sub 2} in 100 ppm increments, replicated twice to allow for a regression analysis. Each chamber was 2 meters on a side and 2 meters tall, which were installed over an individual shrub reprouting after a fire. This manipulation allowed study of the response of native chaparral to varying levels of CO{sub 2}, while regenerating from an experimental burn. Results from these highly-controlled manipulations were compared against Free Air CO{sub 2} Enrichment (FACE) manipulations, in an area adjacent to the CO{sub 2}LT null balance greenhouses. These relatively short-term results (5-7 years) were compared to long-term results from Mediterranean-type ecosystems (MTEs) surrounding natural CO{sub 2} springs in northern Italy, near Laiatico, Italy. The springs lack the controlled experimental rigor of our CO{sub 2}LT and FACE manipulation, but provide invaluable validation of our long-term predictions.

  10. The response of plants to elevated CO2 : I. Competition among an assemblage of annuals at two levels of soil moisture.

    Science.gov (United States)

    Bazzaz, F A; Carlson, R W

    1984-05-01

    Four coexisting annual plant species were grown in competition at three levels of CO2 (300, 600, and 1,200 ppm) and two levels of soil moisture (moist and dry). Plant height was higher at high CO2 concentrations for the three C3 species but not for the C4 species (Amaranthus retroflexus). Total community biomass increased with increasing CO2 at both soil moisture levels. The contribution of each species to total community biomass was influenced by CO2 concentration. The effects were especially pronounced for Polygonum pensylvanicum which contributed more to community production as CO2 and soil moisture increased. Amaranthus behaved in exactly the reverse way; it did best under ambient CO2 and dry soil moisture conditions. The results suggest that changes in competitive interactions and community structure will occur with the anticipated rise in global CO2 concentration.

  11. Response of copepods to elevated pCO2 and environmental copper as co-stressors--a multigenerational study.

    Science.gov (United States)

    Fitzer, Susan C; Caldwell, Gary S; Clare, Anthony S; Upstill-Goddard, Robert C; Bentley, Matthew G

    2013-01-01

    We examined the impacts of ocean acidification and copper as co-stressors on the reproduction and population level responses of the benthic copepod Tisbe battagliai across two generations. Naupliar production, growth, and cuticle elemental composition were determined for four pH values: 8.06 (control); 7.95; 7.82; 7.67, with copper addition to concentrations equivalent to those in benthic pore waters. An additive synergistic effect was observed; the decline in naupliar production was greater with added copper at decreasing pH than for decreasing pH alone. Naupliar production modelled for the two generations revealed a negative synergistic impact between ocean acidification and environmentally relevant copper concentrations. Conversely, copper addition enhanced copepod growth, with larger copepods produced at each pH compared to the impact of pH alone. Copepod digests revealed significantly reduced cuticle concentrations of sulphur, phosphorus and calcium under decreasing pH; further, copper uptake increased to toxic levels that lead to reduced naupliar production. These data suggest that ocean acidification will enhance copper bioavailability, resulting in larger, but less fecund individuals that may have an overall detrimental outcome for copepod populations.

  12. Response of net ecosystem CO2 exchange and evapotranspiration of boreal forest ecosystems to projected future climate changes: results of a modeling study

    Science.gov (United States)

    Olchev, Alexander; Kurbatova, Julia

    2014-05-01

    It is presented the modeling results describing the possible response of net ecosystem exchange of CO2 (NEE), gross (GPP) and net (NPP) primary production, as well as evapotranspiration (ET) of spruce forest ecosystems situated at central part of European part of Russia at the southern boundary of boreal forest community to projected future changes of climatic conditions and forest species composition. A process-based MixFor-SVAT model (Olchev et al 2002, 2008, 2009) has been used to describe the CO2 and H2O fluxes under present and projected future climate conditions. The main advantage of MixFor-SVAT is its ability not only to describe seasonal and daily dynamics of total CO2 and H2O fluxes at an ecosystem level, but also to adequately estimate the contributions of soil, forest understorey, and various tree species in overstorey into total ecosystem fluxes taking into account their individual responses to changes in environmental conditions as well as the differences in structure and biophysical properties. Results of modeling experiments showed that projected changes of climate conditions (moderate scenario A1B IPCC) and forest species composition at the end of 21 century can lead to small increase of annual evapotranspiration as well as to growth of NEE, GPP and NPP of the forests in case if the projected increase in temperature and elevated CO2 in the atmosphere in future will be strictly balanced with growth of available nutrients and water in plant and soil. It is obvious that any deficit of e.g. nitrogen in leaves (due to reduced transpiration, nitrogen availability in soil, etc.) may lead to decreases in the photosynthesis and respiration rates of trees and, as a consequence, to decreases in the GPP and NEE of entire forest ecosystem. Conducted modeling experiments have demonstrated that a 20% reduction of available nitrogen in tree leaves in a monospesific spruce forest stand may result in a 14% decrease in NEE, a 8% decrease in NPP, and a 4% decrease in

  13. CO2NSL (Datalogger)

    DEFF Research Database (Denmark)

    Andersen, Sune Sick

    ,1500 street lamps around Copenhagen will be changed for light sources with low power consumption. Technical and Environmental turn down the energy as a part of Copenhagen goal of reducing the citys CO2 emissions by 20 percent by the end of year 2015. But how much power will the new lamps comsume? And can...

  14. Integrating transient heterogeneity of non-photochemical quenching in shade-grown heterobaric leaves of avocado (Persea americana L.): responses to CO2 concentration, stomatal occlusion, dehydration and relative humidity.

    Science.gov (United States)

    Takayama, Kotaro; King, Diana; Robinson, Sharon A; Osmond, Barry

    2013-11-01

    Long-lived shade leaves of avocado had extremely low rates of photosynthesis. Gas exchange measurements of photosynthesis were of limited use, so we resorted to Chl fluorescence imaging (CFI) and spot measurements to evaluate photosynthetic electron transport rates (ETRs) and non-photochemical quenching (NPQ). Imaging revealed a remarkable transient heterogeneity of NPQ during photosynthetic induction in these hypostomatous, heterobaric leaves, but was adequately integrated by spot measurements, despite long-lasting artifacts from repeated saturating flashes during assays. Major veins (mid-vein, first- and second-order veins) defined areas of more static large-scale heterogeneous NPQ, with more dynamic small-scale heterogeneity most strongly expressed in mesophyll cells between third- and fourth-order veins. Both responded to external CO2 concentration ([CO2]), occlusion of stomata with Vaseline™, leaf dehydration and relative humidity (RH). We interpreted these responses in terms of independent behavior of stomata in adjacent areoles that was largely expressed through CO2-limited photosynthesis. Heterogeneity was most pronounced and prolonged in the absence of net CO2 fixation in 100 p.p.m. [CO2] when respiratory and photorespiratory CO2 cycling constrained the inferred ETR to ~75% of values in 400 or 700 p.p.m. [CO2]. Likewise, sustained higher NPQ under Vaseline™, after dehydration or at low RH, also restricted ETR to ~75% of control values. Low NPQ in chloroplast-containing cells adjacent to major veins but remote from stomata suggested internal sources of high [CO2] in these tissues.

  15. CO2-neutral fuels

    Directory of Open Access Journals (Sweden)

    Goede A. P. H.

    2015-01-01

    Full Text Available The need for storage of renewable energy (RE generated by photovoltaic, concentrated solar and wind arises from the fact that supply and demand are ill-matched both geographically and temporarily. This already causes problems of overcapacity and grid congestion in countries where the fraction of RE exceeds the 20% level. A system approach is needed, which focusses not only on the energy source, but includes conversion, storage, transport, distribution, use and, last but not least, the recycling of waste. Furthermore, there is a need for more flexibility in the energy system, rather than relying on electrification, integration with other energy systems, for example the gas network, would yield a system less vulnerable to failure and better adapted to requirements. For example, long-term large-scale storage of electrical energy is limited by capacity, yet needed to cover weekly to seasonal demand. This limitation can be overcome by coupling the electricity net to the gas system, considering the fact that the Dutch gas network alone has a storage capacity of 552 TWh, sufficient to cover the entire EU energy demand for over a month. This lecture explores energy storage in chemicals bonds. The focus is on chemicals other than hydrogen, taking advantage of the higher volumetric energy density of hydrocarbons, in this case methane, which has an approximate 3.5 times higher volumetric energy density. More importantly, it allows the ready use of existing gas infrastructure for energy storage, transport and distribution. Intermittent wind electricity generated is converted into synthetic methane, the Power to Gas (P2G scheme, by splitting feedstock CO2 and H2O into synthesis gas, a mixture of CO and H2. Syngas plays a central role in the synthesis of a range of hydrocarbon products, including methane, diesel and dimethyl ether. The splitting is accomplished by innovative means; plasmolysis and high-temperature solid oxygen electrolysis. A CO2-neutral fuel

  16. CO2-neutral fuels

    Science.gov (United States)

    Goede, A. P. H.

    2015-08-01

    The need for storage of renewable energy (RE) generated by photovoltaic, concentrated solar and wind arises from the fact that supply and demand are ill-matched both geographically and temporarily. This already causes problems of overcapacity and grid congestion in countries where the fraction of RE exceeds the 20% level. A system approach is needed, which focusses not only on the energy source, but includes conversion, storage, transport, distribution, use and, last but not least, the recycling of waste. Furthermore, there is a need for more flexibility in the energy system, rather than relying on electrification, integration with other energy systems, for example the gas network, would yield a system less vulnerable to failure and better adapted to requirements. For example, long-term large-scale storage of electrical energy is limited by capacity, yet needed to cover weekly to seasonal demand. This limitation can be overcome by coupling the electricity net to the gas system, considering the fact that the Dutch gas network alone has a storage capacity of 552 TWh, sufficient to cover the entire EU energy demand for over a month. This lecture explores energy storage in chemicals bonds. The focus is on chemicals other than hydrogen, taking advantage of the higher volumetric energy density of hydrocarbons, in this case methane, which has an approximate 3.5 times higher volumetric energy density. More importantly, it allows the ready use of existing gas infrastructure for energy storage, transport and distribution. Intermittent wind electricity generated is converted into synthetic methane, the Power to Gas (P2G) scheme, by splitting feedstock CO2 and H2O into synthesis gas, a mixture of CO and H2. Syngas plays a central role in the synthesis of a range of hydrocarbon products, including methane, diesel and dimethyl ether. The splitting is accomplished by innovative means; plasmolysis and high-temperature solid oxygen electrolysis. A CO2-neutral fuel cycle is

  17. Responses of enchytraeids to increased temperature, drought and atmospheric CO2: Results of an eight-year field experiment in dry heathland

    DEFF Research Database (Denmark)

    Holmstrup, Martin; Schmelz, Rüdiger M.; Carrera, Noela

    2015-01-01

    In a long-term field trial we investigated the responses of enchytraeids to simulated future climatic conditions predicted for Denmark. At a semi-natural Danish heathland site we exposed 9.1 m2 plots to elevated atmospheric CO2 concentration (510 ppm), extended summer drought and passive night...... in spring 2013, perhaps indicating that warming stimulates fragmentation (reproduction) rates at this time of the year. Increased drought in MayeJune 2012 did not have lasting effects on abundance or biomass 3 months after the termination of drought treatment. However, comparison with earlier assessments...... of enchytraeids in the CLIMAITE experiment shows that the severity of drought and the time elapsed since the last drought is the best predictor of the biovolume (or biomass) of enchytraeids. Moreover, species richness was significantly impacted by the average soil water content experienced by enchytraeids during...

  18. Rain pulse response of soil CO2 exchange by biological soil crusts and grasslands of the semiarid Colorado Plateau, United States

    Science.gov (United States)

    Bowling, David R.; Grote, E.E.; Belnap, J.

    2011-01-01

    Biological activity in arid grasslands is strongly dependent on moisture. We examined gas exchange of biological soil crusts (biocrusts), the underlying soil biotic community, and the belowground respiratory activity of C3 and C4 grasses over 2 years in southeast Utah, USA. We used soil surface CO2 flux and the amount and carbon isotope composition (δ13C) of soil CO2 as indicators of belowground and soil surface activity. Soil respiration was always below 2 μmol m-2s-1 and highly responsive to soil moisture. When moisture was available, warm spring and summer temperature was associated with higher fluxes. Moisture pulses led to enhanced soil respiration lasting for a week or more. Biological response to rain was not simply dependent on the amount of rain, but also depended on antecedent conditions (prior moisture pulses). The short-term temperature sensitivity of respiration was very dynamic, showing enhancement within 1-2 days of rain, and diminishing each day afterward. Carbon uptake occurred by cyanobacterially dominated biocrusts following moisture pulses in fall and winter, with a maximal net carbon uptake of 0.5 μmol m-2s-1, although typically the biocrusts were a net carbon source. No difference was detected in the seasonal activity of C3 and C4 grasses, contrasting with studies from other arid regions (where warm- versus cool-season activity is important), and highlighting the unique biophysical environment of this cold desert. Contrary to other studies, the δ13C of belowground respiration in the rooting zone of each photosynthetic type did not reflect the δ13C of C3 and C4 physiology.

  19. The Flux-Anomaly-Forced Model Intercomparison Project (FAFMIP) Contribution to CMIP6: Investigation of Sea-Level and Ocean Climate Change in Response to CO2 Forcing

    Science.gov (United States)

    Gregory, Jonathan M.; Bouttes, Nathaelle; Griffies, Stephen M.; Haak, Helmuth; Hurlin, William J.; Jungclaus, Johann; Kelley, Maxwell; Lee, Warren G.; Marshall, John; Romanou, Anastasia; hide

    2016-01-01

    The Flux-Anomaly-Forced Model Intercomparison Project (FAFMIP) aims to investigate the spread in simulations of sea-level and ocean climate change in response to CO2 forcing by atmosphere-ocean general circulation models (AOGCMs). It is particularly motivated by the uncertainties in projections of ocean heat uptake, global-mean sealevel rise due to thermal expansion and the geographical patterns of sea-level change due to ocean density and circulation change. FAFMIP has three tier-1 experiments, in which prescribed surface flux perturbations of momentum, heat and freshwater respectively are applied to the ocean in separate AOGCM simulations. All other conditions are as in the pre-industrial control. The prescribed fields are typical of pattern and magnitude of changes in these fluxes projected by AOGCMs for doubled CO2 concentration. Five groups have tested the experimental design with existing AOGCMs. Their results show diversity in the pattern and magnitude of changes, with some common qualitative features. Heat and water flux perturbation cause the dipole in sea-level change in the North Atlantic, while momentum and heat flux perturbation cause the gradient across the Antarctic Circumpolar Current. The Atlantic meridional overturning circulation (AMOC) declines in response to the heat flux perturbation, and there is a strong positive feedback on this effect due to the consequent cooling of sea-surface temperature in the North Atlantic, which enhances the local heat input to the ocean. The momentum and water flux perturbations do not substantially affect the AMOC. Heat is taken up largely as a passive tracer in the Southern Ocean, which is the region of greatest heat input, while the weakening of the AMOC causes redistribution of heat towards lower latitudes. Future analysis of these and other phenomena with the wider range of CMIP6 FAFMIP AOGCMs will benefit from new diagnostics of temperature and salinity tendencies, which will enable investigation of the model

  20. CO2-Switchable Membranes Prepared by Immobilization of CO2-Breathing Microgels.

    Science.gov (United States)

    Zhang, Qi; Wang, Zhenwu; Lei, Lei; Tang, Jun; Wang, Jianli; Zhu, Shiping

    2017-12-20

    Herein, we report the development of a novel CO 2 -responsive membrane system through immobilization of CO 2 -responsive microgels into commercially available microfiltration membranes using a method of dynamic adsorption. The microgels, prepared from soap-free emulsion polymerization of CO 2 -responsive monomer 2-(diethylamino)ethyl methacrylate (DEA), can be reversibly expanded and shrunken upon CO 2 /N 2 alternation. When incorporated into the membranes, this switching behavior was preserved and further led to transformation between microfiltration and ultrafiltration membranes, as indicated from the dramatic changes on water flux and BSA rejection results. This CO 2 -regulated performance switching of membranes was caused by the changes of water transportation channel, as revealed from the dynamic water contact angle tests and SEM observation. This work represents a simple yet versatile strategy for making CO 2 -responsive membranes.

  1. CHRONIC EXPOSURE OF A FRESHWATER MUSSEL TO ELEVATED pCO2 : EFFECTS ON THE CONTROL OF BIOMINERALIZATION AND ION-REGULATORY RESPONSES.

    Science.gov (United States)

    Jeffrey, Jennifer D; Hannan, Kelly D; Hasler, Caleb T; Suski, Cory D

    2017-10-02

    Freshwater mussels may be exposed to elevations in pCO2 due to both natural and anthropogenic factors. The goal of the present study was to assess the effects of a 28-d elevation in pCO2 , at 15,000 and 50,000 µatm, on processes associated with biomineralization, ion regulation, and cellular stress in adult Lampsilis siliquoidea (Barnes, 1823). In addition, the capacity for mussels to compensate for acid-base disturbances experienced following exposure to elevated pCO2 was assessed over a 14-d recovery period. Overall, exposure to 50,000 µatm pCO2 had more pronounced physiological consequences compared to 15,000 µatm pCO2 . Over the first 7 d of exposure to 50,000 µatm pCO2 , the mRNA abundance of chitin synthase (cs), calmodulin (cam), calmodulin-like protein (calp) were significantly affected, suggesting that shell formation and integrity may be altered during pCO2 exposure. Following the removal of the pCO2 treatment, mussels may compensate for the acid-base and ion disturbances experienced during pCO2 exposure, and transcript levels of some regulators of biomineralization (carbonic anhydrase, ca; cs, cam, calp) as well as ion regulation (na(+) -k(+) -ATPase, nka) were modulated. Effects of elevated pCO2 on heat shock protein 70 (hsp70) were limited in the present study. Overall, adult L. siliquoidea appeared to regulate factors associated with the control of biomineralization and ion regulation during and/or following the removal of pCO2 exposure. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  2. Relationship of bronchodilator response with oxygen pulse and ventilatory threshold in children with asthma: the effect of body composition and progressive aerobic activity in an environment with low humidity

    Directory of Open Access Journals (Sweden)

    Samera Puyan majd

    2015-11-01

    Full Text Available Background: Asthma is a leading cause of chronic illness in children, impacting heavily on their daily complications. The purpose of the present study was to relationship bronchodilator response (BDR with oxygen pulse (OP and ventilatory threshold (VT in asthma children with various body compositions during progressive aerobic activities. Material and Methods: 25 obese children (BMI>25 and %fat>30with asthma(10 subjects, and healthy children (15 subjects  and 25 lean children(BMI<20 and %fat<20 with asthma(13 subjects, and healthy children (7 subjects performed an exercise protocol in a constant temperature environment 2 ± 22 ° C and humidity (5 ± 35%. During exercise, the steady-state levels of cardio-respiratory parameters were measured using gas analyzer (K4B2. Results: The results showed that after a progressive aerobic activity, values peak oxygen consumption(vo2peak ​​, bronchodilator(BDR, oxygen pulse(OP and ventilatory threshold(VT  in lean and obese asthmatic children were lower than in healthy lean and obese children. In addition, lean children with asthma had lower VT and higher VO2peak , OP and BDR values​​, as compared obese asthmatic children. Between BDR and VT in lean and obese asthmatic children an inverse relationship between BDR and OP and a direct link to asthma in obese children and obese asthmatic children, there was a negative relationship non-significant. Conclusion: Compared with lean children, asthma, obesity as an additional load will affect lung function and increase the pressure on childhood asthma. Therefore, we can accept that obesity may limit performance of exercise in childhood asthma.

  3. Yield responses of wild C3and C4crop progenitors to subambient CO2: a test for the role of CO2limitation in the origin of agriculture.

    Science.gov (United States)

    Cunniff, Jennifer; Jones, Glynis; Charles, Michael; Osborne, Colin P

    2017-01-01

    Limitation of plant productivity by the low partial pressure of atmospheric CO 2 (C a ) experienced during the last glacial period is hypothesized to have been an important constraint on the origins of agriculture. In support of this hypothesis, previous work has shown that glacial C a limits vegetative growth in the wild progenitors of both C 3 and C 4 founder crops. Here, we present data showing that glacial C a also reduces grain yield in both crop types. We grew four wild progenitors of C 3 (einkorn wheat and barley) and C 4 crops (foxtail and broomcorn millets) at glacial and postglacial C a , measuring grain yield and the morphological and physiological components contributing to these yield changes. The C 3 species showed a significant increase in unthreshed grain yield of ~50% with the glacial to postglacial increase in C a , which matched the stimulation of photosynthesis, suggesting that increases in photosynthesis are directly translated into yield at subambient levels of C a . Increased yield was controlled by a higher rate of tillering, leading to a larger number of tillers bearing fertile spikes, and increases in seed number and size. The C 4 species showed smaller, but significant, increases in grain yield of 10-15%, arising from larger seed numbers and sizes. Photosynthesis was enhanced by C a in only one C 4 species and the effect diminished during development, suggesting that an indirect mechanism mediated by plant water relations could also be playing a role in the yield increase. Interestingly, the C 4 species at glacial C a showed some evidence that photosynthetic capacity was upregulated to enhance carbon capture. Development under glacial C a also impacted negatively on the subsequent germination and viability of seeds. These results suggest that the grain production of both C 3 and C 4 crop progenitors was limited by the atmospheric conditions of the last glacial period, with important implications for the origins of agriculture. © 2016

  4. Response of the rhizosphere prokaryotic community of barley (Hordeum vulgare L.) to elevated atmospheric CO2 concentration in open-top chambers.

    Science.gov (United States)

    Szoboszlay, Márton; Näther, Astrid; Mitterbauer, Esther; Bender, Jürgen; Weigel, Hans-Joachim; Tebbe, Christoph C

    2017-08-01

    The effect of elevated atmospheric CO2 concentration [CO2 ] on the diversity and composition of the prokaryotic community inhabiting the rhizosphere of winter barley (Hordeum vulgare L.) was investigated in a field experiment, using open-top chambers. Rhizosphere samples were collected at anthesis (flowering stage) from six chambers with ambient [CO2 ] (approximately 400 ppm) and six chambers with elevated [CO2 ] (700 ppm). The V4 region of the 16S rRNA gene was PCR-amplified from the extracted DNA and sequenced on an Illumina MiSeq instrument. Above-ground plant biomass was not affected by elevated [CO2 ] at anthesis, but plants exposed to elevated [CO2 ] had significantly higher grain yield. The composition of the rhizosphere prokaryotic communities was very similar under ambient and elevated [CO2 ]. The dominant taxa were Bacteroidetes, Actinobacteria, Alpha-, Gamma-, and Betaproteobacteria. Elevated [CO2 ] resulted in lower prokaryotic diversity in the rhizosphere, but did not cause a significant difference in community structure. © 2017 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

  5. Independent, interactive, and species-specific responses of leaf litter decomposition to elevated CO2 and O3 in a northern hardwood forest

    Science.gov (United States)

    William F.J. Parsons; James G. Bockheim; Richard L. Lindroth

    2008-01-01

    The future capacity of forest ecosystems to sequester atmospheric carbon is likely to be influenced by CO2-mediated shifts in nutrient cycling through changes in litter chemistry, and by interactions with pollutants like O3. We evaluated the independent and interactive effects of elevated CO2 and O...

  6. Varying response of the concentration and content of soybean seed mineral elements, carbohydrates, organic acids, amino acids, protein, and oil to phosphorus starvation and CO2 enrichment

    Science.gov (United States)

    A detailed investigation of the concentration (g-1 seed weight) and content (g plant-1) of seed mineral elements and metabolic profile under phosphorus (P) starvation at ambient (aCO2) and elevated carbon dioxide (eCO2) in soybean is limited. Soybean plants were grown in a controlled environment at ...

  7. The effect of subambient to elevated atmospheric CO2 concentration on vascular function in Helianthus annuus: Implications for plant response to climate change

    Science.gov (United States)

    Plant gas-exchange is regulated by stomata, which co-ordinate leaf-level water loss with xylem transport. Stomatal opening responds to internal levels of CO2 in the leaf but changing CO2 can also lead to changes in stomatal density that influence transpiration. Given that stomatal conductance increa...

  8. Growth, reproductive phenology and yield responses of a potential biofuel plant, Jatropha curcas grown under projected 2050 levels of elevated CO2.

    Science.gov (United States)

    Kumar, Sumit; Chaitanya, Bharatula S K; Ghatty, Sreenivas; Reddy, Attipalli R

    2014-11-01

    Jatropha (Jatropha curcas) is a non-edible oil producing plant which is being advocated as an alternative biofuel energy resource. Its ability to grow in diverse soil conditions and minimal requirements of essential agronomical inputs compared with other oilseed crops makes it viable for cost-effective advanced biofuel production. We designed a study to investigate the effects of elevated carbon dioxide concentration ([CO(2)]) (550 ppm) on the growth, reproductive development, source-sink relationships, fruit and seed yield of J. curcas. We report, for the first time that elevated CO(2) significantly influences reproductive characteristics of Jatropha and improve its fruit and seed yields. Net photosynthetic rate of Jatropha was 50% higher in plants grown in elevated CO(2) compared with field and ambient CO(2) -grown plants. The study also revealed that elevated CO(2) atmosphere significantly increased female to male flower ratio, above ground biomass and carbon sequestration potential in Jatropha (24 kg carbon per tree) after 1 year. Our data demonstrate that J. curcas was able to sustain enhanced rate of photosynthesis in elevated CO(2) conditions as it had sufficient sink strength to balance the increased biomass yields. Our study also elucidates that the economically important traits including fruit and seed yield in elevated CO(2) conditions were significantly high in J. curcas that holds great promise as a potential biofuel tree species for the future high CO(2) world. © 2014 Scandinavian Plant Physiology Society.

  9. The Flux-Anomaly-Forced Model Intercomparison Project (FAFMIP contribution to CMIP6: investigation of sea-level and ocean climate change in response to CO2 forcing

    Directory of Open Access Journals (Sweden)

    J. M. Gregory

    2016-11-01

    Full Text Available The Flux-Anomaly-Forced Model Intercomparison Project (FAFMIP aims to investigate the spread in simulations of sea-level and ocean climate change in response to CO2 forcing by atmosphere–ocean general circulation models (AOGCMs. It is particularly motivated by the uncertainties in projections of ocean heat uptake, global-mean sea-level rise due to thermal expansion and the geographical patterns of sea-level change due to ocean density and circulation change. FAFMIP has three tier-1 experiments, in which prescribed surface flux perturbations of momentum, heat and freshwater respectively are applied to the ocean in separate AOGCM simulations. All other conditions are as in the pre-industrial control. The prescribed fields are typical of pattern and magnitude of changes in these fluxes projected by AOGCMs for doubled CO2 concentration. Five groups have tested the experimental design with existing AOGCMs. Their results show diversity in the pattern and magnitude of changes, with some common qualitative features. Heat and water flux perturbation cause the dipole in sea-level change in the North Atlantic, while momentum and heat flux perturbation cause the gradient across the Antarctic Circumpolar Current. The Atlantic meridional overturning circulation (AMOC declines in response to the heat flux perturbation, and there is a strong positive feedback on this effect due to the consequent cooling of sea-surface temperature in the North Atlantic, which enhances the local heat input to the ocean. The momentum and water flux perturbations do not substantially affect the AMOC. Heat is taken up largely as a passive tracer in the Southern Ocean, which is the region of greatest heat input, while the weakening of the AMOC causes redistribution of heat towards lower latitudes. Future analysis of these and other phenomena with the wider range of CMIP6 FAFMIP AOGCMs will benefit from new diagnostics of temperature and salinity tendencies, which will enable

  10. Linking gene expression to productivity to unravel long- and short-term responses of seagrasses exposed to CO2 in volcanic vents

    Science.gov (United States)

    Olivé, Irene; Silva, João; Lauritano, Chiara; Costa, Monya M.; Ruocco, Miriam; Procaccini, Gabriele; Santos, Rui

    2017-02-01

    Ocean acidification is a major threat for marine life but seagrasses are expected to benefit from high CO2. In situ (long-term) and transplanted (short-term) plant incubations of the seagrass Cymodocea nodosa were performed near and away the influence of volcanic CO2 vents at Vulcano Island to test the hypothesis of beneficial effects of CO2 on plant productivity. We relate, for the first time, the expression of photosynthetic, antioxidant and metal detoxification-related genes to net plant productivity (NPP). Results revealed a consistent pattern between gene expression and productivity indicating water origin as the main source of variability. However, the hypothesised beneficial effect of high CO2 around vents was not supported. We observed a consistent long- and short-term pattern of gene down-regulation and 2.5-fold NPP decrease in plants incubated in water from the vents and a generalized up-regulation and NPP increase in plants from the vent site incubated with water from the Reference site. Contrastingly, NPP of specimens experimentally exposed to a CO2 range significantly correlated with CO2 availability. The down-regulation of metal-related genes in C. nodosa leaves exposed to water from the venting site suggests that other factors than heavy metals, may be at play at Vulcano confounding the CO2 effects.

  11. Response of Rates and Sources of Ecosystem CO2 Efflux to Increasing Levels of Winter Snow Depth in the High Arctic of Northwest Greenland

    Science.gov (United States)

    Thomas, J. S.; Lupascu, M.; Xu, X.; Maseyk, K. S.; Welker, J. M.; Czimczik, C. I.

    2011-12-01

    Arctic soils contain vast amounts of organic carbon (C) that range in age from modern to ancient. These soil C pools may be especially vulnerable to changes in conditions; especially increases in winter snowfall, as deeper snow will insulate soils in winter, and add moisture in summer. While, snowfall is increasing in many parts of the Arctic, how increases in winter precipitation affect C cycling in the High Arctic is largely unknown. In this project, we used a long-term snowpack manipulation to develop a better understanding of current and future soil C cycling under conditions of deep winter snow pack and the associated feedbacks to future atmospheric CO2 levels. We examined the effects of three levels of winter snowpack (ambient (0.25 m), ×2, ×4) on the timing, magnitude and sources of ecosystem CO2 efflux and soil microclimate in prostrate dwarf-shrub tundra on patterned ground in the High Arctic of NW Greenland. From June to August 2010 and 2011 we monitored ecosystem CO2 efflux and soil CO2 concentrations (LI-COR 800 & 840) together with soil temperature and moisture daily and the radiocarbon (14C) content of CO2 monthly. The 14C content of CO2 can be used to infer the dominant source of CO2 (plant vs. microbially-respired) as well as the age of microbially-respired CO2. Initial results indicate that during the 2010 sampling period (Jun 28 - Aug 16), daily CO2 emissions from vegetated areas were higher under ×4 ambient snowpack relative to ambient snowpack (84.9 vs. 53.1 mmol m-2 d-1), but lower under ×2 ambient snowpack (56.7 mmol m-2 d-1). CO2 emissions from bare areas increased with snowpack depth from ambient (8.6 mmol m-2 d-1) to ×2 ambient snowpack (16.5 mmol m-2 d-1) to x4 ambient snowpack (18.9 mmol m-2 d-1). Midsummer ecosystem CO2 emissions were dominated by modern C; additional 14C measurements are in progress. Our findings indicate that increases in snowpack may stimulate C loss from this high arctic ecosystem - probably facilitated by

  12. Breathing pattern and ventilatory chemosensitivity of the 1-day old Muscovy duck (Cairina moschata) in relation to its metabolic demands.

    Science.gov (United States)

    Mortola, Jacopo P; Toro-Velasquez, Paula Andrea

    2014-01-01

    Adult birds have a ventilatory equivalent (pulmonary ventilation-oxygen consumption ratio, V˙ E/ [Formula: see text] ) lower than mammals because of the superior gas exchange efficiency of their respiratory apparatus. In particular, adult Muscovy ducks (Cairina moschata) have been reported to have an extraordinary low ventilatory equivalent (~14mL STPD·mL BTPS(-1)). We asked if similar high efficiency was already apparent in duck hatchlings. Breathing pattern and V˙E were measured by the barometric technique and [Formula: see text] by an open-flow methodology in 1-day old Muscovy duck hatchlings (N=21); same measurements were performed on chicken hatchlings (N=21) for purpose of comparison. During air breathing V˙E/ [Formula: see text] was slightly, yet significantly, lower in ducklings (20.8) than in chicks (25.3), mostly because of a lower breathing frequency (f). The hatchlings of both species (N=14 per group) responded to inspired hypoxia (15 or 10% O2) or hypercapnia (2 or 4% CO2) with a clear hyperventilation; however, in ducklings the hypercapnic hyperventilation was smaller than in chicks because of a smaller increase in tidal volume and lower f. We conclude that duck and chicken hatchlings just a few hours old have the high ventilatory efficiency typical of birds, although possibly not as high as their adults. The low f and blunted V˙E response to hypercapnia of the newborn duck could be related to the aquatic habitat of the species. In such a case, it would mean that these characteristics are genetic traits, the phenotypic expression of which does not require diving experience. © 2013.

  13. Swelling response of radiation synthesized 2-hydroxyethylmethacrylate-co-[2-(methacryloyloxy)ethyl] trimethylammonium chloride hydrogels under various in vitro conditions.

    Science.gov (United States)

    Goel, N K; Kumar, Virendra; Bhardwaj, Y K; Chaudhari, C V; Dubey, K A; Sabharwal, S

    2009-01-01

    High-energy (60)Co gamma radiation has been used to synthesize 2-hydroxyethylmethacrylate-co-[2-(methacryloyloxy)ethyl]trimethylammonium chloride (HEMA-co-MAETC) polyelectrolyte hydrogels. HEMA-co-MAETC co-polymer gels were characterized and investigated for swelling behaviour in different swelling conditions. Fourier transformed infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) techniques were used to characterize the co-polymer gels. Swelling extent of the gels was found to be a linear function of MAETC content in the gels. The effect of ionic strength, temperature, pH, some solutes of biological importance like glucose, urea, and surfactants such as Triton-X and deoxycholic acid on swelling behavior have been reported. The swelling of gels at higher temperature enhanced the swelling rates but not the swelling extent. HEMA-co-MAETC hydrogel exhibited an excellent responsive characteristic to the ionic strength of the swelling medium. It was found that the swelling of the co-polymer gel at 60 degrees C reduced the swelling-deswelling cycle time by approx. 30% without altering the swelling extent. The gels were also investigated for their swelling in aqueous solutions of anionic dyes, acid blue 25 (AB25), acid blue (AB74) and acid yellow 99 (AY99), and were found to be suitable for dye uptake applications.

  14. A lipophilic ionic liquid based on formamidinium cations and TFSI: the electric response and the effect of CO2 on the conductivity mechanism.

    Science.gov (United States)

    Bertasi, Federico; Giffin, Guinevere A; Vezzù, Keti; Pace, Giuseppe; Abu-Lebdeh, Yaser; Armand, Michel; Di Noto, Vito

    2017-10-04

    This work describes the preparation of the new lipophilic ionic liquid tetraoctyl-formamidinium bis(trifluoromethanesulfonyl) imide (TOFATFSI), which is miscible with lower alkanes. In particular, this work focuses on the electric behaviour of TOFATFSI in the particularly challenging highly apolar environment of supercritical CO2. The conductivity and relaxation phenomena are revealed through the analysis of the broadband electric spectra with a particular emphasis on the effect of temperature and CO2 uptake on the IL conductivity. It is found that temperature boosts the conductivity via an increase in the charge carrier mobility. Also, CO2 absorption affects both the conductivity and the permittivity of the material due to the presence of CO2-IL interactions that modulate the nanostructure and the size of the TOFATFSI aggregates, which increases both the mobility and the density of the charge carriers.

  15. A squaraine-based colorimetric and F(-) dependent chemosensor for recyclable CO2 gas detection: highly sensitive off-on-off response.

    Science.gov (United States)

    Xia, Guomin; Liu, Yang; Ye, Benfei; Sun, Jianqi; Wang, Hongming

    2015-09-18

    An unsymmetrical squaraine-based chemosensor SH2 has been synthesized, and its sensing behavior towards CO2 gas was described in detail by UV-vis and (1)H NMR spectroscopies in DMSO. The results indicated that the extremely sensitive "naked-eye" CO2 gas detection can be operated in the presence of excess [Bu4N]F (TBAF) and the sensor is easy to recycle. These properties enable SH2 to act as a CO2 and F(-) controlled "OFF-ON-OFF" switch. Combining theoretical analyses, a plausible sensing mechanism was proposed to illustrate how the receptor SH2 works as a CO2 sensitive and selective colorimetric probe in the present system.

  16. Seasonality of soil moisture mediates responses of ecosystem phenology to elevated CO2 and warming in a semi‐arid grassland

    National Research Council Canada - National Science Library

    Zelikova, Tamara J; Williams, David G; Hoenigman, Rhonda; Blumenthal, Dana M; Morgan, Jack A; Pendall, Elise; Guo, Dali

    2015-01-01

    .... We used repeat photography and a novel means of quantifying greenness in digital photographs to assess how the individual and combined effects of warming and elevated CO 2 impact ecosystem phenology...

  17. Process coupling and control over the response of net ecosystem CO2 exchange to climate variability and insect disturbance in subalpine forests of the Western US

    Science.gov (United States)

    Monson, R. K.; Moore, D. J.; Trahan, N. A.; Scott-Denton, L.; Burns, S. P.; Hu, J.; Bowling, D. R.

    2011-12-01

    Following ten years of studies in subalpine forest ecosystems of the Western US, we have concluded that the tight coupling between gross primary productivity (GPP) and the autotrophic component of soil respiration (Ra) drives responses of net ecosystem CO2 exchange (NEE) to climate variability and insect disturbance. This insight has been gained through long-term eddy flux observations, manipulative plot experiments, analyses of dynamics in the stable isotope compositions of CO2 and H2O, and chamber gas-exchange measurements. Using past observations from these studies, we deployed model-data assimilation techniques and forecast weather/climate modeling to estimate how the coupling between GPP and Ra is likely to affect future (Year 2100) dynamics in NEE. The amount of winter snow and its melting dynamics in the spring represents the dominant control over interannual variation in GPP. Using the SIPNET ecosystem process model, combined with knowledge about the stable isotope content of different water sources, we estimated that approximately 75% of growing season GPP is coupled to the use of snowmelt water, whereas approximately 25% is coupled to summer rain. The tight coupling between GPP and winter snow pack drives a similar tight coupling between soil respiration (Rs) and winter snow pack. Manipulation of snow pack on forest plots has shown that Rs increases with increased snow pack, and this effect disappears when trees are girdled, which stops the transfer of GPP to roots and the soil rhizosphere. Higher-than-normal winter snowpacks cause the carbon isotope ratios of soil-respired CO2 to be depleted in 13C, reflecting a signal of lower photosynthetic water-use efficiency in the GPP that is transferred to the soil rhizosphere. Large-scale forest disturbance due to catastrophic tree mortality from mountain pine beetle attack causes an initial (2-3 year) reduction in Rs, which is attributable to the loss of GPP and its effect on Ra. This near-term reduction in Rs

  18. Minocycline blocks glial cell activation and ventilatory acclimatization to hypoxia.

    Science.gov (United States)

    Stokes, Jennifer A; Arbogast, Tara E; Moya, Esteban A; Fu, Zhenxing; Powell, Frank L

    2017-04-01

    Ventilatory acclimatization to hypoxia (VAH) is the time-dependent increase in ventilation, which persists upon return to normoxia and involves plasticity in both central nervous system respiratory centers and peripheral chemoreceptors. We investigated the role of glial cells in VAH in male Sprague-Dawley rats using minocycline, an antibiotic that inhibits microglia activation and has anti-inflammatory properties, and barometric pressure plethysmography to measure ventilation. Rats received either minocycline (45mg/kg ip daily) or saline beginning 1 day before and during 7 days of chronic hypoxia (CH, PiO2  = 70 Torr). Minocycline had no effect on normoxic control rats or the hypercapnic ventilatory response in CH rats, but minocycline significantly (P minocycline administration during only the last 3 days of CH did not reverse VAH. Microglia and astrocyte activation in the nucleus tractus solitarius was quantified from 30 min to 7 days of CH. Microglia showed an active morphology (shorter and fewer branches) after 1 h of hypoxia and returned to the control state (longer filaments and extensive branching) after 4 h of CH. Astrocytes increased glial fibrillary acidic protein antibody immunofluorescent intensity, indicating activation, at both 4 and 24 h of CH. Minocycline had no effect on glia in normoxia but significantly decreased microglia activation at 1 h of CH and astrocyte activation at 24 h of CH. These results support a role for glial cells, providing an early signal for the induction but not maintenance of neural plasticity underlying ventilatory acclimatization to hypoxia.NEW & NOTEWORTHY The signals for neural plasticity in medullary respiratory centers underlying ventilatory acclimatization to chronic hypoxia are unknown. We show that chronic hypoxia activates microglia and subsequently astrocytes. Minocycline, an antibiotic that blocks microglial activation and has anti-inflammatory properties, also blocks astrocyte activation in respiratory

  19. Response of microbial extracellular enzyme activities and r- vs. K- selected microorganisms to elevated atmospheric CO2 depends on soil aggregate size

    Science.gov (United States)

    Dorodnikov, Maxim; Blagodatskaya, Evgenia; Blagodatskiy, Sergey; Kuzyakov, Yakov

    2014-05-01

    Increased belowground carbon (C) transfer by plant roots under elevated atmospheric CO2 and the contrasting environment in soil macro- and microaggregates could affect properties of the microbial community in the rhizosphere. We evaluated the effect of 5 years of elevated CO2 (550 ppm) on four extracellular enzymes: ß-glucosidase, chitinase, phosphatase, and sulfatase along with the contribution of fast- (r-strategists) and slow-growing microorganisms (K-strategists) in soil aggregates. We fractionated the bulk soil from the ambient and elevated CO2 treatments of FACE-Hohenheim (Stuttgart) into large macro- (>2 mm), small macro- (0.25-2.00 mm), and microaggregates (chitinase activity in bulk soil and in large macroaggregates under elevated CO2 revealed an increased contribution of fungi to turnover processes. We conclude that quantitative and qualitative changes of C input by plants into the soil at elevated CO2 affect microbial community functioning, but not its total content. An increase in r-selected microorganisms could accelerate C turnover in terrestrial ecosystems under a future CO2-elevated atmosphere.

  20. Allocation of secondary metabolites, photosynthetic capacity, and antioxidant activity of Kacip Fatimah (Labisia pumila Benth) in response to CO2 and light intensity.

    Science.gov (United States)

    Ibrahim, Mohd Hafiz; Jaafar, Hawa Z E; Karimi, Ehsan; Ghasemzadeh, Ali

    2014-01-01

    A split plot 3 by 4 experiment was designed to investigate and distinguish the relationships among production of secondary metabolites, soluble sugar, phenylalanine ammonia lyase (PAL; EC 4.3.1.5) activity, leaf gas exchange, chlorophyll content, antioxidant activity (DPPH), and lipid peroxidation under three levels of CO2 (400, 800, and 1200 μ mol/mol) and four levels of light intensity (225, 500, 625, and 900 μ mol/m(2)/s) over 15 weeks in Labisia pumila. The production of plant secondary metabolites, sugar, chlorophyll content, antioxidant activity, and malondialdehyde content was influenced by the interactions between CO2 and irradiance. The highest accumulation of secondary metabolites, sugar, maliondialdehyde, and DPPH activity was observed under CO2 at 1200 μ mol/mol + light intensity at 225 μ mol/m(2)/s. Meanwhile, at 400 μ mol/mol CO2 + 900 μ mol/m(2)/s light intensity the production of chlorophyll and maliondialdehyde content was the highest. As CO2 levels increased from 400 to 1200 μ mol/mol the photosynthesis, stomatal conductance, f v /f m (maximum efficiency of photosystem II), and PAL activity were enhanced. The production of secondary metabolites displayed a significant negative relationship with maliondialdehyde indicating lowered oxidative stress under high CO2 and low irradiance improved the production of plant secondary metabolites that simultaneously enhanced the antioxidant activity (DPPH), thus improving the medicinal value of Labisia pumila under this condition.

  1. Ventilatory demand and dynamic hyperinflation induced during ADL-based tests in Chronic Obstructive Pulmonary Disease patients

    Directory of Open Access Journals (Sweden)

    Karoliny dos Santos

    2016-01-01

    Full Text Available ABSTRACT Background Airflow limitation frequently leads to the interruption of activities of daily living (ADL in patients with Chronic Obstructive Pulmonary Disease (COPD. These patients commonly show absence of ventilatory reserve, reduced inspiratory reserve volume, and dynamic hyperinflation (DH. Objective To investigate ventilatory response and DH induced by three ADL-based protocols in COPD patients and compare them to healthy subjects. Method Cross-sectional study. COPD group: 23 patients (65±6 years, FEV1 37.2±15.4%pred; control group: 14 healthy subjects (64±4 years matched for age, sex, and body mass index. Both groups performed all three tests: Glittre-ADL test; an activity test that involved moving objects on a shelf (TSHELF; and a modified shelf protocol isolating activity with upper limbs (TSHELF-M. Ventilatory response and inspiratory capacity were evaluated. Results Baseline ventilatory variables were similar between groups (p>0.05. The ventilatory demand increased and the inspiratory capacity decreased significantly at the end of the tests in the COPD group. Ventilatory demand and DH were higher (p0.05 and ventilatory demand increased at the end of the tests (p<0.05 but to a lower extent than the COPD group. Conclusion The TSHELF induces similar ventilatory responses to the Glittre-ADL test in COPD patients with higher ventilatory demand and DH. In contrast, the ventilatory response was attenuated in the TSHELF-M, suggesting that squatting and bending down during the Glittre-ADL test could trigger significant ventilatory overload.

  2. Ventilatory Efficiency in Children and Adolescents Born Extremely Preterm

    Science.gov (United States)

    Hestnes, Julie; Hoel, Hedda; Risa, Ole J.; Romstøl, Hanna O.; Røksund, Ola; Frisk, Bente; Thorsen, Einar; Halvorsen, Thomas; Clemm, Hege H.

    2017-01-01

    Purpose: Children and adolescents born extremely preterm (EP) have lower dynamic lung volumes and gas transfer capacity than subjects born at term. Most studies also report lower aerobic capacity. We hypothesized that ventilatory efficiency was poorer and that breathing patterns differed in EP−born compared to term−born individuals. Methods: Two area−based cohorts of participants born with gestational age ≤28 weeks or birth weight ≤1000 g in 1982−85 (n = 46) and 1991–92 (n = 35) were compared with individually matched controls born at term. Mean ages were 18 and 10 years, respectively. The participants performed an incremental treadmill exercise test to peak oxygen uptake with data averaged over 20 s intervals. For each participant, the relationship between exhaled minute ventilation (V˙E) and carbon dioxide output (V˙CO2) was described by a linear model, and the relationship between tidal volume (VT) and V˙E by a quadratic model. Multivariate regression analyses were done with curve parameters as dependent variables, and the categories EP vs. term−born, sex, age, height, weight and forced expiratory volume in 1 s (FEV1) as independent variables. Results: In adjusted analyses, the slope of the V˙E−V˙CO2 relationship was significantly steeper in the EP than the term-born group, whereas n