The Role of Callistemon Fruits and Infructescences in Protecting Seeds from Heat in Fires

1998 ◽  
Vol 46 (2) ◽  
pp. 235 ◽  
Author(s):  
Claire L. Brown ◽  
Robert J. Whelan
Keyword(s):  
High Temperature ◽  
Seed Germination ◽  
High Intensity ◽  
Room Temperature ◽  
Seed Viability ◽  
Protective Role ◽  
Percentage Germination ◽  
Low Intensity ◽  
Australian Plant

A number of Australian plant species tolerate fires because seeds are protected in woody fruits and are released after fire, but there is little information about the role of the fruit, or a collection of fruits, in protecting seed from the heat of a fire. This study examined the effects of various temperatures applied to infructescences of Callistemon citrinus (Curtis) Skeels on seed germination. The protective role of the dense collection of fruits in maintaining seed viability was tested by experimentally ‘thinning’ infructescences before heating. Heating of infructescences significantly increased the percentage of seeds germinating from less than 20% at room temperature to over 35% at 200˚C, but caused a decline, with further temperature increase to 800˚C. There was a slight but statistically significant increase in the percentage germination of seeds from thinned infructescences. Increased germination following exposure to high temperature may be a way for a plant to synchronise germination after high-intensity fire, while spreading it out if seeds are released in the absence of fire or after a low-intensity fire.

scholarly journals Involvement of 5-HT3 receptors in pudendal inhibition of bladder overactivity in cats

2013 ◽  
Vol 305 (5) ◽  
pp. F663-F671 ◽  
Author(s):  
Zeyad Schwen ◽  
Yosuke Matsuta ◽  
Bing Shen ◽  
Jicheng Wang ◽  
James R. Roppolo ◽  
...  
Keyword(s):  
High Intensity ◽  
Bladder Capacity ◽  
Saline Control ◽  
Low Intensity ◽  
Afferent Nerves ◽  
Normal Bladder ◽  
Pudendal Neuromodulation ◽  
Bladder Symptoms ◽  
Bladder Activity

In the present study, the role of 5-HT3 receptors in pudendal neuromodulation of bladder activity and its interaction with opioid receptors were investigated in anesthetized cats. The bladder was distended with either saline to induce normal bladder activity or with 0.25% acetic acid (AA) to induce bladder overactivity. Pudendal afferent nerves were activated by 5-Hz stimulation at multiples of the threshold (T) intensity for the induction of anal twitching. AA irritation significantly reduced bladder capacity to 16.5 ± 3.3% of saline control capacity, whereas pudendal nerve stimulation (PNS) at 1.5–2 and 3–4 T restored the capacity to 82.0 ± 12% ( P = 0.0001) and 98.6 ± 15% ( P < 0.0001), respectively. Cumulative doses (1–3 mg/kg iv) of ondansetron, a 5-HT3 receptor antagonist, eliminated low-intensity (1.5–2 T) PNS inhibition and reduced high-intensity (3–4 T) PNS inhibition of bladder overactivity. During saline distention, PNS at 1.5–2 and 3–4 T significantly increased bladder capacity to 173.2 ± 26.4% ( P = 0.036) and 193.2 ± 22.5% ( P = 0.008), respectively, of saline control capacity, but ondansetron (0.003–3 mg/kg iv) did not alter PNS inhibition. Ondansetron (0.1–3 mg/kg) also significantly ( P < 0.05) increased control bladder capacity (50–200%) during either AA irritation or saline distention. In both conditions, the effects of low- and high-intensity PNS were not significantly different. After ondansetron (3 mg/kg) treatment, naloxone (1 mg/kg iv) significantly ( P < 0.05) decreased control bladder capacity (40–70%) during either AA irritation or saline distention but failed to affect PNS inhibition. This study revealed that activation of 5-HT3 receptors has a role in PNS inhibition of bladder overactivity. It also indicated that 5-HT3 receptor antagonists might be useful for the treatment of overactive bladder symptoms.

An Experimental Study on the Contribution of Fire Retardant Coating to the Fire Protection of Concrete

2013 ◽  
Vol 405-408 ◽  
pp. 2660-2664
Author(s):  
Wei Jun Cao ◽  
Man Li Ou ◽  
Fang Cheng Liu
Keyword(s):  
High Temperature ◽  
Cross Section ◽  
Fire Retardant ◽  
Concrete Specimen ◽  
Equilibrium Temperature ◽  
Protective Role ◽  
Surface Fire ◽  
Temperature Test ◽  
Test Result

The mechanical property of the concrete under high temperature will go through great changes with much greater deformation. The uneven temperature distribution causes equilibrium temperature stress of the cross section and deformation of components, thus damaging the structure system of the concrete. This paper conducts a high-temperature test on the C25 concrete specimen with fire retardant coating, compares the test result with the test on the C25 concrete specimen without fire retardant coating, and analyzes the protective role of the surface fire retardant coating in the concrete structure buildings in case of fire.

The Mediational Mole of Social Influence in the Perception of Exertion

1986 ◽  
Vol 8 (2) ◽  
pp. 88-104 ◽  
Author(s):  
Charles J. Hardy ◽  
Evelyn G. Hall ◽  
Perry H. Prestholdt
Keyword(s):  
Social Influence ◽  
High Intensity ◽  
Physiological Responses ◽  
Cycle Ergometer ◽  
The Self ◽  
Self Perception ◽  
Psychological Variables ◽  
Low Intensity ◽  
Mediational Role

Two experiments are reported that investigate the mediational role of social influence in the self-perception of exertion. In Experiment 1, subjects performed three 15-min trials on a cycle ergometer at 25%, 50%, and 75% VO2max, both in the presence of another performer (a coactor) and alone. The results indicated that subjects reported lower RPEs when performing with another, particularly at the moderate (50%) intensity. In Experiment 2, subjects performed one 15-min trial at 50% of VO2max, both alone and in the presence of another performer (coactor) exhibiting nonverbal "cues" that the work was either extremely easy or extremely difficult. The results indicated that subjects exposed to the low-intensity cue information reported lower RPEs than when performing alone. Mo significant differences were noted for those subjects exposed to the high-intensity cue information. These findings are discussed in terms of a self-presentational analysis. That such effects were evidenced without physiological responses (VO2, VE, HR) accompanying them supports the notion that psychological variables can play a significant role in the self-perception of exertion. These results, however, are limited to untrained individuals exercising at moderate intensities.

Stabilization of high temperature hexagonal phase of SrAl2O4 at room temperature: role of ZnO

2014 ◽  
Vol 43 (14) ◽  
pp. 5309 ◽  
Author(s):  
V. P. Singh ◽  
S. B. Rai ◽  
H. Mishra ◽  
Chandana Rath
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Hexagonal Phase

scholarly journals Effect of High-Temperature Stress on Plant Physiological Traits and Mycorrhizal Symbiosis in Maize Plants

2021 ◽  
Vol 7 (10) ◽  
pp. 867
Author(s):  
Sonal Mathur ◽  
Richa Agnihotri ◽  
Mahaveer P. Sharma ◽  
Vangimalla R. Reddy ◽  
Anjana Jajoo
Keyword(s):  
High Temperature ◽  
Temperature Stress ◽  
Soil Microbial Communities ◽  
High Temperature Stress ◽  
Protective Role ◽  
Physiological Parameters ◽  
Ps Ii ◽  
Below Ground ◽  
Maize Plants

Increasing high temperature (HT) has a deleterious effect on plant growth. Earlier works reported the protective role of arbuscular mycorrhizal fungi (AMF) under stress conditions, particularly influencing the physiological parameters. However, the protective role of AMF under high-temperature stress examining physiological parameters with characteristic phospholipid fatty acids (PLFA) of soil microbial communities including AMF has not been studied. This work aims to study how high-temperature stress affects photosynthetic and below-ground traits in maize plants with and without AMF. Photosynthetic parameters like quantum yield of photosystem (PS) II, PSI, electron transport, and fractions of open reaction centers decreased in HT exposed plants, but recovered in AMF + HT plants. AMF + HT plants had significantly higher AM-signature 16:1ω5cis neutral lipid fatty acid (NLFA), spore density in soil, and root colonization with lower lipid peroxidation than non-mycorrhizal HT plants. As a result, enriched plants had more active living biomass, which improved photosynthetic efficiency when exposed to heat. This study provides an understanding of how AM-mediated plants can tolerate high temperatures while maintaining the stability of their photosynthetic apparatus. This is the first study to combine above- and below-ground traits, which could lead to a new understanding of plant and rhizosphere stress.

scholarly journals Germination responses of seeds of Desmodium triflorum

2018 ◽  
Vol 4 (2) ◽  
pp. 19 ◽  
Author(s):  
Niroj Paudel ◽  
Prakash Deep Rai
Keyword(s):  
Seed Germination ◽  
Blue Light ◽  
White Light ◽  
Red Light ◽  
Light Condition ◽  
Dark Condition ◽  
Percentage Germination ◽  
Negative Effect

<p class="abstract"><strong>Background:</strong> Germination of <em>Desmodium triflorum</em> is used for the scarification using the acid is valuable for the different light condition.</p><p class="abstract"><strong>Methods:</strong> The sample was collected as four month of interval of time and the seed is treated with acids with different time.  </p><p class="abstract"><strong>Results:</strong> seeds scarified with sulfuric acids for 10 min before sowing had better germination than those scarified for 5 and 15 min. Among them light qualities, red and white light had slightly promoted effect whereas blue light and dark condition had slightly negative effect on seed germination.</p><p><strong>Conclusions:</strong> In comparison to blue light and dark condition, red light and white light were promoted to percentage germination indicating the role of phytochrome in seed germination of <em>Desmodium triflorum</em>. </p>

scholarly journals Heat and cold stresses phenotypes of Arabidopsis thaliana calmodulin mutants: regulation of gamma-aminobutyric acid shunt pathway under temperature stress

2012 ◽  
Vol 3 (1) ◽  
pp. 2 ◽  
Author(s):  
Nisreen A. AL-Quraan ◽  
Robert D. Locy ◽  
Narendra K. Singh
Keyword(s):  
Arabidopsis Thaliana ◽  
Heat Stress ◽  
High Temperature ◽  
Seed Germination ◽  
Oxidative Damage ◽  
Temperature Stress ◽  
Wild Type ◽  
Gaba Shunt ◽  
Heat And Cold Stress

Plants have evolved mechanisms to cope with changes in surrounding temperatures. T-DNA insertions in seven calmodulin genes of <em>Arabidopsis thaliana</em> were used to investigate the role of specific calmodulin isoforms in tolerance of plants to low and high temperature for seed germination, susceptibility to low and high temperature induced oxidative damage, and changes in the levels of gammaaminobutyric acid (GABA) shunt metabolites in response to temperature stress. Exposure of wild type (WT) and <em>cam</em> mutant seeds at 4°C showed reduction in germination of <em>cam5-4</em> and <em>cam6-1</em> seeds. Exposure of cam seedlings to 42°C for 2 hr showed reduction in seed germination and survival of seedlings in <em>cam5-4</em> and <em>cam6-1</em> mutants compared to WT and other <em>cam</em> mutants. Oxidative damage by heat and cold stress measured as the level of malonaldehyde (MDA) was detected increased in root and shoot tissues of cam5- 4 and cam6-1. Oxidative damage by heat measured as the level of MDA was detected in root and shoot of most cam mutants with highest levels in <em>cam5-4</em> and <em>cam6-1</em>. Level of GABA shunt metabolites in seedlings were gradually increased after 1 hr and 3 hr with maximum level after 6 hr and 12 hr treatments at 4ºC. GABA shunt metabolites in both root and shoot were generally elevated after 30 min and 1 hr treatment at 42°C, and increased substantially after 2 hr at 42°C comparing to the control (no treatment). GABA and glutamate levels were increased significantly more than alanine in root and shoot tissues of all cam mutants and wild type compared to the control. Alanine levels showed significant decreases in all cam mutants and in WT for 30 and 60 min of heat stress. Sensitivity of <em>cam5-4 </em>and <em>cam6-1</em> to low temperatures suggests a role of the <em>CAM5</em> and <em>CAM6</em> genes in seed germination and protection against cold induced oxidative damage. Increases in the level of GABA shunt metabolites in response to cold treatment after initial reduction in some cam mutants suggests a role for calmodulin protein (<em>cam</em>) in the activation of glutamate decarboxylase (GAD) after exposure to cold, while increased metabolite levels may indicate involvement of other factors like reduction in cytoplasmic pH in cold regulation. Initial general elevation in GABA shunt metabolites after 30 min heat treatment in cam mutants suggests regulation of GABA level by <em>cam</em>. These data suggest that regulation by factors other than cam is likely, and that this factor may relate to the regulation of GAD by intracellular pH and/or metabolite partitioning under heat stress.

scholarly journals 402 Lettuce Seed Germination and Endo-mannanase Activity are Stimulated by Ethylene at High Temperature

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 513B-513 ◽  
Author(s):  
Warley M. Nascimento ◽  
Daniel J. Cantliffe ◽  
Donald J. Huber
Keyword(s):  
High Temperature ◽  
Seed Germination ◽  
Enzyme Regulation ◽  
Seed Priming ◽  
Lettuce Seed ◽  
Endosperm Cell ◽  
Lettuce Seeds ◽  
Mannanase Activity ◽  
Lettuce Seed Germination

Temperatures above 30 °C may delay or inhibit germination of most of commercial lettuce cultivars. Ethylene enhances lettuce seed germination at high temperatures. Enzyme-mediated degradation of endosperm cell walls appears to be a crucial factor for lettuce germination at high temperature. The galactomannan polysaccharides in lettuce endosperm cell wall are mobilized by endomannanase. The role of endo-mannanase during germination of lettuce seeds at high temperature (35 °C) and the possible role of etlene in enzyme regulation were investigated. Seeds of thermotolerant (`Everglades'-EVE) and thermosensitive (`Dark Green Boston'-DGB) lettuce genotypes were incubated at 20 and 35 °C in water, 10 mM of 1-aminocyclopropane-1-carboxylic acid (ACC), or 20 mM of silver thiosulphate (STS). Also, seeds were primed in an aerated solution of polyethylene glycol (PEG), or PEG+ACC, or PEG+STS. Untreated seeds germinated 100% at 20 °C. At 35 °C, EVE germinated 100%, whereas DGB germinated only 33%. Seed priming or adding ACC during imbibition increased germination of DGB to 100% at 35 °C. Adding STS during imbibition led to a decrease in germination at 35%C in EVE and completely inhibited germination of DGB. Priming with STS led to reduced germination at 35%C of both genotypes. EVE produced more ethylene than DGB during germination at high temperature. Providing ACC either during priming or during germination led to an increase in endo-mannanase activity, whereas STS inhibited mannanase activity. Higher endo-mannana activity was observed in EVE than DGB seeds. The results suggest that ethylene might overcome the inhibitory effect of high temperature in thermosensitive lettuce seeds via weakening of endosperm due to increased endo-mannanase activity.

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