Desiccation-Tolerant Plants under Elevated Air CO2: A Review

1999 ◽  
Vol 54 (9-10) ◽  
pp. 788-796 ◽  
Author(s):  
Zoltán Tuba ◽  
Michael C. F. Proctor ◽  
Zoltán Takács
Keyword(s):  
Positive Response ◽  
Feedback Inhibition ◽  
Short Term ◽  
Photosynthetic Organisms ◽  
Tolerant Plants ◽  
Ecophysiological Responses ◽  
Source Sink ◽  
Theoretical Considerations ◽  
Water Contents ◽  
Excessive Water

This article summarises present knowledge of the ecophysiological responses to elevated atmospheric CO2 of desiccation tolerant (DT) plants. It deals primarily with lichens and bryophytes, as the most prominent groups of DT photosynthetic organisms, but includes some comment on algae and vascular DT plants. Results of research on DT plants are compared with those on desiccation sensitive vascular C3 plants, the most widely investigated group in the field of global change. Both DT and non-DT plants show an immediate positive response of photosynthesis to elevated CO2, but in both groups the longer term effect is generally reduced (or even reversed) by down-regulation or feedback inhibition of photosynthesis, or other limitations on production and growth. In bryophytes and lichens, enhanced short-term photosynthesis may or may not be reflected in increased production; bryophytes have limited source-sink differentiation, and lichens invest excess photosynthate in secondary metabolites. DT plants may gain some advantage from elevated CO2 at both low and excessive water contents. Neither theoretical considerations nor experimental results suggest that elevated atmospheric CO2 will lead to any substantial shift in the balance of advantage between DT and non-DT plants

Regulation of sucrose-phosphate synthase in wheat (Triticum aestivum) leaves

2004 ◽  
Vol 31 (7) ◽  
pp. 685 ◽  
Author(s):  
Stephen J. Trevanion ◽  
C. Kate Castleden ◽  
Christine H. Foyer ◽  
Robert T. Furbank ◽  
W. Paul Quick ◽  
...  
Keyword(s):  
Triticum Aestivum ◽  
Feedback Inhibition ◽  
Sucrose Phosphate Synthase ◽  
High Light ◽  
Sucrose Synthesis ◽  
Short Term ◽  
Cereal Species ◽  
Wheat Leaves ◽  
Sucrose Phosphate ◽  
Phosphate Synthase

The regulation of sucrose-phosphate synthase (SPS, E.C. 2.4.1.14), a key enzyme of sucrose synthesis, was investigated in wheat (Triticum aestivum L.) leaves. Wheat SPS was activated in the light, with an increased affinity for its substrates and the activator glucose-6-phosphate, reduced sensitivity to inhibition by Pi, but no change in maximum catalytic activity. Based on these properties, assays to measure the total activity and activation state of the enzyme were established and validated using several different wheat cultivars, grown under different environmental conditions. As found in previous studies on other species, e.g. spinach, activation appeared to be linked to the prevailing rate of photosynthesis rather than light per se. Long-term exposure to higher light levels increased total SPS activity in the leaves, and some experiments indicated that this response could occur within 1 h of exposure of low-light-grown plants to high light. However, activation of pre-existing enzyme was a more common short-term response to high light. Wheat, like many important cereal species, stores a large amount of sucrose in its leaves. In contrast with spinach, which stores more starch in its leaves, accumulation of sucrose in wheat leaves did not lead to inactivation of SPS or inhibition of sucrose synthesis. In conclusion, the mechanisms linking the rates of sucrose synthesis and photosynthetic CO2 fixation in wheat leaves appear to be similar to those in other species, but the mechanisms involved in short-term feedback inhibition of sucrose synthesis by sucrose, found in starch-storing species, are lacking in wheat.

scholarly journals Short-term plasticity in glomerular inhibitory circuits shapes olfactory bulb output

2020 ◽  
Vol 123 (3) ◽  
pp. 1120-1132 ◽  
Author(s):  
Fu-Wen Zhou ◽  
Zuo-Yi Shao ◽  
Michael T. Shipley ◽  
Adam C. Puche
Keyword(s):  
Fluorescent Protein ◽  
Feedback Inhibition ◽  
Olfactory Nerve ◽  
Inhibitory Synapses ◽  
Acid Decarboxylase ◽  
Short Term ◽  
Short Term Plasticity ◽  
Inhibitory Circuits ◽  
Frequency Independent ◽  
Green Fluorescent

Short-term plasticity is a fundamental synaptic property thought to underlie memory and neural processing. The glomerular microcircuit comprises complex excitatory and inhibitory interactions and transmits olfactory nerve signals to the excitatory output neurons, mitral/tufted cells (M/TCs). The major glomerular inhibitory interneurons, short axon cells (SACs) and periglomerular cells (PGCs), both provide feedforward and feedback inhibition to M/TCs and have reciprocal inhibitory synapses between each other. Olfactory input is episodically driven by sniffing. We hypothesized that frequency-dependent short-term plasticity within these inhibitory circuits could influence signals sent to higher-order olfactory networks. To assess short-term plasticity in glomerular circuits and MC outputs, we virally delivered channelrhodopsin-2 (ChR2) in glutamic acid decarboxylase-65 promotor (GAD2-cre) or tyrosine hydroxylase promoter (TH-cre) mice and selectively activated one of these two populations while recording from cells of the other population or from MCs. Selective activation of TH-ChR2-expressing SACs inhibited all recorded GAD2-green fluorescent protein(GFP)-expressing presumptive PGC cells, and activation of GAD2-ChR2 cells inhibited TH-GFP-expressing SACs, indicating reciprocal inhibitory connections. SAC synaptic inhibition of GAD2-expressing cells was significantly facilitated at 5–10 Hz activation frequencies. In contrast, GAD2-ChR2 cell inhibition of TH-expressing cells was activation-frequency independent. Both SAC and PGC inhibition of MCs also exhibited short-term plasticity, pronounced in the 5–20 Hz range corresponding to investigative sniffing frequency ranges. In paired SAC and olfactory nerve electrical stimulations, the SAC to MC synapse was able to markedly suppress MC spiking. These data suggest that short-term plasticity across investigative sniffing ranges may differentially regulate intra- and interglomerular inhibitory circuits to dynamically shape glomerular output signals to downstream targets. NEW & NOTEWORTHY Short-term plasticity is a fundamental synaptic property that modulates synaptic strength based on preceding activity of the synapse. In rodent olfaction, sensory input arrives episodically driven by sniffing rates ranging from quiescent respiration (1–2 Hz) through to investigative sniffing (5–10 Hz). Here we show that glomerular inhibitory networks are exquisitely sensitive to input frequencies and exhibit plasticity proportional to investigative sniffing frequencies. This indicates that olfactory glomerular circuits are dynamically modulated by episodic sniffing input.

Field Evaluation of Late Merge Traffic Control in Work Zones

2005 ◽  
Vol 1911 (1) ◽  
pp. 33-41 ◽  
Author(s):  
Andrew G. Beacher ◽  
Michael D. Fontaine ◽  
Nicholas J. Garber
Keyword(s):  
Field Test ◽  
Traffic Control ◽  
Positive Response ◽  
Field Evaluation ◽  
Field Studies ◽  
Work Zone ◽  
Work Zones ◽  
Short Term ◽  
Term Field ◽  
Lane Closures

The traffic control strategy of the late merge in work zones was devised to improve flow and safety at work zone lane closures. Although some states have put the strategy into practice, only a handful of short-term field studies have formally evaluated its effectiveness. Additional field studies were necessary to assess the efficacy of the strategy and its proper deployment. This paper documents the results of a field test of the late merge traffic control conducted over several months. The late merge strategy was evaluated by comparing its effectiveness with that of traditional plans for work zone lane closures. The field test was conducted on a primary route in Tappahannock, Virginia, at a two-to-one lane closure. Results showed that throughput increased, but the increase was not statistically significant. Likewise, time in queue decreased, but the decrease was not statistically significant. These results were much less dramatic than those of other studies. Possible reasons for this disparity include different driver populations, road types, vehicle mixes, and site-specific characteristics. Despite limited improvements in throughput and time in queue, more drivers were in the closed lane, a positive response to the late merge signs.

Triptans in Orgasmic Headache

Cephalalgia ◽  
2006 ◽  
Vol 26 (12) ◽  
pp. 1458-1461 ◽  
Author(s):  
A Frese ◽  
A Gantenbein ◽  
M Marziniak ◽  
IW Husstedt ◽  
PJ Goadsby ◽  
...  
Keyword(s):  
Sexual Activity ◽  
Positive Response ◽  
Therapeutic Option ◽  
International Headache Society ◽  
Severe Headache ◽  
Activity Type ◽  
Short Term ◽  
International Headache Society Classification ◽  
Short Term Prophylaxis

Orgasmic headache (headache associated with sexual activity type 2 according to the International Headache Society classification) is a sudden severe headache which occurs at orgasm. Experiences with triptan therapy are described. Two out of four patients with severe headache continuing for >2 h had a positive response to acute triptan therapy. Two out of three patients using triptans as short-term prophylaxis reported a reliable response on several occasions. Trip- tans might be a treatment option to shorten orgasmic headache attacks after the diagnosis is clear and, particularly, subarachnoid haemorrhage has been excluded. In patients who chose to predict their sexual activity, short-term prophylaxis with oral triptans 30 min before sexual activity might be a therapeutic option in those not responsive to or not tolerating indomethacin.

scholarly journals Interneuron diversity is required for compartment-specific feedback inhibition

2020 ◽  
Author(s):  
Joram Keijser ◽  
Henning Sprekeler
Keyword(s):  
Functional Role ◽  
Feedback Inhibition ◽  
Inhibitory Interneurons ◽  
Optimization Approach ◽  
Short Term ◽  
Short Term Plasticity ◽  
Specific Feedback

AbstractCortical inhibitory interneurons consist of many subtypes that have been associated with different functions. Here we use an optimization approach to show that two classes of interneurons are necessary to implement compartment-specific feedback inhibition to pyramidal cells.The two classes resemble PV-expressing and SST-expressing interneurons in their connectivity and short-term plasticity, suggesting a functional role for their diverse characteristics.

scholarly journals Nanotube-mediated cross-feeding couples the metabolism of interacting bacterial cells

2017 ◽  
Author(s):  
Shraddha Shitut ◽  
Tobias Ahsendorf ◽  
Samay Pande ◽  
Matthew Egbert ◽  
Christian Kost
Keyword(s):  
Amino Acid ◽  
Feedback Inhibition ◽  
Bacterial Cells ◽  
Loss Of Function ◽  
E Coli ◽  
Donor Cells ◽  
Mere Presence ◽  
Source Sink ◽  
Amino Acid Concentrations ◽  
Amino Acid Biosynthetic Pathway

ABSTRACTBacteria frequently engage in cross-feeding interactions that involve an exchange of metabolites with other micro- or macroorganisms. The often obligate nature of these associations, however, hampers manipulative experiments, thus limiting our mechanistic understanding of the ecophysiological consequences that result for the organisms involved. Here we address this issue by taking advantage of a well-characterised experimental model system, in which auxotrophic genotypes ofE. coliderive essential amino acid from prototrophic donor cells using intercellular nanotubes. Surprisingly, donor-recipient cocultures revealed that the mere presence of auxotrophic genotypes in coculture was sufficient to increase amino acid production levels in donor cells. Subsequent experiments unravelled that this effect was due to the depletion of amino acid concentrations in the cytoplasm of donor cells, which delayed feedback inhibition of the corresponding amino acid biosynthetic pathway. This finding indicates that in newly established mutualistic associations, an intercellular regulation of exchanged metabolites can simply emerge from the architecture of the underlying biosynthetic pathways, rather than through the evolution of new regulatory mechanisms. Taken together, our results show that a single loss-of-function mutation can physiologically couple the metabolism of two cross-feeding cells in a source-sink-like relationship.

scholarly journals The Short-Term Reliability of Metaphors as an Assessment Method

2021 ◽  
Vol 6 ◽  
Author(s):  
Elisabeth Wegner ◽  
Christian Burkhart ◽  
Matthias Nückles
Keyword(s):  
Assessment Method ◽  
Educational Science ◽  
Short Term ◽  
Surface Approach ◽  
Innovative Tool ◽  
The Stability ◽  
The Moment ◽  
Theoretical Considerations

Metaphors are assumed to be a means of accessing implicit aspects of cognition. Metaphors, therefore, have been increasingly used in educational science as an innovative tool to examine a broad range of constructs. However, there are both empirical findings and theoretical considerations suggesting that metaphors are also by experiences that are salient just in the moment of production of the metaphor. Therefore, we examined in a sample of N = 95 students and professionals whether the metaphors of learning and the underlying conceptualization of learning that influence whether students adopt a deep or a surface approach in learning remained stable across 3 weeks. Results showed that although the sources on which the metaphors drew were subject to change, the underlying conceptualization of learning remained stable. However, there were no differences in the stability of metaphors in both groups. It be can concluded, therefore, that metaphors can be used as an indicator for underlying constructs such as the understanding of learning.

TENS for pain management

2014 ◽  
Keyword(s):  
Electrical Stimulation ◽  
Pain Management ◽  
Pain Relief ◽  
Positive Response ◽  
Emotional Experience ◽  
Tertiary Care ◽  
Medical Attention ◽  
Short Term ◽  
Over Time

Pain is a sensory and emotional experience often related to tissue damage. Pain requiring medical attention is common, with pain assessment and management often challenging. TENS is offered within primary, secondary, and tertiary care settings because it has a favourable utility profile compared with pain-relieving medication. Evidence suggests that most individuals who try TENS report meaningful pain relief in the short-term, but this positive response declines over time. The purpose of this chapter is to contextualise the role of TENS in the management of pain by covering what pain is, the challenges faced in its management, the physiology of the nociceptive system, including states of sensitivity, electrophysical techniques for pain and rehabilitation, including invasive electrical stimulation techniques, the extent of use of TENS, and some discussion of the clinical experience of using TENS.

Isothermal micro-calorimetry: a tool to predict seed longevity?

2006 ◽  
Vol 16 (2) ◽  
pp. 89-96 ◽  
Author(s):  
Fiona R. Hay ◽  
Michael A.A. O'Neill ◽  
Anthony E. Beezer ◽  
Simon Gaisford
Keyword(s):  
Heat Flow ◽  
Water Content ◽  
High Water ◽  
Seed Longevity ◽  
Total Heat ◽  
Short Term ◽  
Seed Ageing ◽  
Rate Kinetics ◽  
Residual Power ◽  
Water Contents

This paper describes the exploratory use of isothermal micro-calorimetry (IMC) to measure directly the heat flow produced as seeds age. Heat flow was recorded in primed and non-primed (control) seeds of Ranunculus sceleratus L., aged in a micro-calorimeter at 35°C at three different seed water contents [c. 0.12, 0.075 and 0.045 g H2O (g dw)−1]. The rate of heat flow and total heat generated (an indicator of extent of reaction) were generally greater in control seeds, which aged at a faster rate, than in primed seeds. Total heat generated over a given period also increased with increasing water content. The power–time curves did not indicate first- or second-order rate kinetics, consistent with the probability that seed ageing is complex and involves a number of reactions. Even after the capacity to germinate had ceased, there was a residual power signal. As a method, IMC gave consistent results using independent samples at different times. Therefore, short-term experiments at relatively high water contents and/or temperatures may have the potential to predict the relative longevity of seed-lots, at least within a species.

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