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9453. Soybean stomatal aclimation to long-term exposure to CO2-enriched atmospheres

Creator:
Chen, X.M., Begonia, G.B., and Hesketh, J.D.
Format:
print
Type:
model:internalpart and TEXT
Subject:
Glycine max (L.), transpiration rate, stomatal conductance, open top chamber, and net photosynthetic rate
Language:
Multiple languages
Description:
Soybean [Glycine max (L.) cv. Jack] grown in open top chambers under controlled laboratory and field conditions was ušed to study the acclimation of leaf gas exchange processes to CO2 enrichment. Air inside the open top chambers was maintained at either 700-800 or 350-400 pmol(C02) mol'^(air). Leaf gas exchange rates were measured for some plants switched between treatments. When measmed in the C02-emiched atmosphere, stomatal conductances (gg) were higher in leaves grown in C02-enriched atmospheres than in those grown under ambient conditions, and the lower gg values for plants in the C02-enriched atmospheres were limiting to leaf net photosynthetic CO2 exchange rates (Pn). of enriched leaves was higher than those of the ambient Controls when measured at elevated CO2 levels in both controlled environment and field studies, while it was depressed in enriched leaves when measured imder ambient CO2 conditions, and this drop in Pn did not recover until 6-15 d after plants were placed back in ambient conditions.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

9455. Spatial navigation: implications for animal models, drug development and human studies

Creator:
Aleš Stuchlík, Kubik, S., Kamil Vlček, and Karel Valeš
Format:
print
Type:
article, články, model:article, and TEXT
Subject:
Fyziologie člověka a srovnávací fyziologie, paměť, učení, navigace, mozek, neurony, memory, learning, navigation, brain, neurons, spatial representation, moving environments, rats, animal models, 14, and 612
Language:
English
Description:
Spatial navigation and memory is considered to be a part of the declarative memory system and it is widely used as an animal model of human declarative me mory. However, spatial tests typically involve only static settings, despite the dynamic nature of the real world. Animals, as well as people constantly need to interact with moving objects, other subjects or even with entire moving environments (flowing water, running stairway). Therefore, we design novel spatial tests in dynamic environments to study brain mechanisms of spatial processing in more natural settings with an interdisciplinary approach including neuropharmacology. We also translate data from neuropharmacological studies and animal models into development of novel therapeutic approaches to neuropsychiatric disorders and more sensitive screening tests for impairments of memory, thought, and behavior., A. Stuchlik ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

9456. Species specific diurnal changes in chlorophyll fluorescence in tropical deciduous and evergreen plants growing in the field during summer

Creator:
Joshi, S.C.
Format:
print
Type:
model:internalpart and TEXT
Subject:
Acer, Aesculus, Bauhinia, Boehmeria, Celtis, Dalbergia, Eugenia, Ficus, Grewia, and Sapium
Language:
Multiple languages
Description:
Diumal changes in chlorophyll (Chl) a fluorescence characteristics of sun-exposed and shade leaves of some tropical and temperate tree species growing under fíeld conditions on sunny and cloudy days during summer were recorded. Significant reduction in photochemical efficiency of photosystem (PS) 2 measured as ratio during periods of maximum irradiance was observed in sun-exposed leaves of some plants. The extent of this reduction was probably a function of the plant species. Among the tropical species tested, Boehmeria rugulosa, Celíis ausíralis, Dalbergia sissoo, Eugenia jambolana and Grewia optiva showed maximum reduction (15-22 %), whereas species like Ficus racemosa and Sapium sebiferum showed least dechne (< 7 %) in the F^/F^ ratio. On the other hand, no significant reduction in this ratio was observed in Bauhinia purpurea. Temperate species, v/z. Acer oblongum and Aesculus indica, were most susceptible to high irradiances. Prolonged exposure of these plants to high irradiances resulted in lesion development in their leaves characterized by reduction in pigment contents and Fy/F^, ratio. Plant species with considerable midday dechne in Fy/Fn, ratio showed (7) slight but significant rise in initial fluorescence (Fq), (2) pronounced decrease in F^ value, and (3) significant reduction in area over the curve between Fq and Fj„ indicating the pool size of electron acceptors on the reducing side of PS2. The depression in Fy/F^ ratio though reversible could not be alleviated even after watering the plants at hourly intervals. No reduction in Fy/F^, was observed in shade leaves of the same plants and/or when measurements were taken on cloudy days. Hence high solar radiation and high atmospheric evaporative demand existing during summer period could probably be the major contributoiy factors for this reduction.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

9457. Specific leaf area variations drive acclimation of Cistus salvifolius in different light environments

Creator:
Puglielli, G., Varone, L., Gratani, L., and Catoni, R.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
karotenoidy, carotenoids, aklimatizace, acclimatization, fluorescence chlorofylu, výměna plynu, absorptance listu, Cistus salvifolius, list, chlorophyll fluorescence, gas exchange, leaf absorptance, leaf nitrogen partitioning, leaf, 2, and 581
Language:
Multiple languages
Description:
Cistus salvifolius L. is the most widely spread Cistus species around the Mediterranean basin. It colonizes a wide range of habitats growing from sea level to 1,800 m a.s.l., on silicolous and calcicolous soils, in sun areas as well as in the understory of wooded areas. Nevertheless, this species has been mainly investigated in term of its responsiveness to drought. Our aim was to understand which leaf traits allow C. salvifolius to cope with low-light environments. We questioned if biochemical and physiological leaf trait variations in response to a reduced photosynthetic photon flux density were related to leaf morphological plasticity, expressed by variations of specific leaf area (SLA) and its anatomical components (leaf tissue density and thickness). C. salvifolius shrubs growing along the Latium coast (41°43'N,12°18'E, 14 m a.s.l., Italy) in the open and in the understory of a Pinus pinea forest, were selected and the relationships between anatomical, gas exchange, chlorophyll (Chl) fluorescence, and biochemical parameters with SLA and PPFD variations were tested. The obtained results suggested long-term acclimation of the selected shrubs to contrasting light environments. In high-light conditions, leaf nitrogen and Chl contents per leaf area unit, leaf thickness, and Chl a/b ratio increased, thus maximizing net photosynthesis, while in shade photosynthesis, it was downregulated by a significant reduction in the electron transport rate. Nevertheless, the increased pigment-protein complexes and the decreased Chl a/b in shade drove to an increased light-harvesting capacity (i.e. higher actual quantum efficiency of PSII). Moreover, the measured vitality index highlighted the photosynthetic acclimation of C. salvifolius to contrasting light environments. Overall, our results demonstrated the morphological, anatomical, and physiological acclimation of C. salvifolius to a reduced light environment., G. Puglielli, L. Varone, L. Gratani, R. Catoni., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

9458. Specific photosynthetic and morphological characteristics allow macroalgae Gloiopeltis furcata (Rhodophyta) to survive in unfavorable conditions

Creator:
Huan, L., Gao, S., Xie, X. J., Tao, W. R., Pan, G. H., Zhang, B. Y., Niu, J. F., Lin, A. P., He, L. W., and Wang, G. C.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
fotosyntéza, morfologie (biologie), photosynthesis, morphology (biology), cyclic electron flow, desiccation, Dual-PAM, salinity, Gloiopeltis furcata, Rhodophyta, 2, and 581
Language:
Multiple languages
Description:
Gloiopeltis furcata (Postels & Ruprecht) J. Agardh, a macroalga, which grows in an upper, intertidal zone, can withstand drastic environmental changes caused by the periodic tides. In this study, the photosynthetic and morphological characteristics of G. furcata were investigated. The photosynthetic performance and electron flows of the thalli showed significant variations in response to desiccation and salinity compared with the control group. Both PSII and PSI activities declined gradually when the thalli were under stress. However, the electron transport rate of PSI showed still a low value during severe conditions, while the rate of PSII approached zero. Furthermore, PSI activity of the treated thalli recovered faster than PSII after being submerged in seawater. Even though the linear electron flow was inhibited by DCMU [3-(3, 4-dichlorophenyl)-1,1-dimethylurea], the cyclic electron flow could still be restored. The rate of cyclic electron flow recovery declined with the increasing time of dark treatment, which suggested that stromal reductants from starch degradation played an important role in the donation of electrons to PSI. This study demonstrated that PSII was more sensitive than PSI to desiccation and salinity in G. furcata and that the cyclic electron flow around PSI played a significant physiological role. In addition, G. furcata had branches, which were hollow inside and contained considerable quantities of funoran. These might be the most important factors in allowing G. furcata to adapt to adverse intertidal environments., L. Huan, S. Gao, X. J. Xie, W. R. Tao, G. H. Pan, B. Y. Zhang, J. F. Niu, A. P. Lin, L. W. He, G. C. Wang., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

9459. Spectra and exciton dynamics in circular aggregates of the photosynthetic apparatus

Creator:
Novoderezhkin, V.I. and Razjivin, A.P.
Format:
print
Type:
model:internalpart and TEXT
Subject:
absorbance spectra, light-harvesting pigments, fluorescence spectra, fluorescence kinetics, depolarization, bleaching, and absorption anisotropy
Language:
Multiple languages
Description:
A theory of spectra and excitation dynamics in antenna based on the notion of exciton interactions in the cyclic structures of light-harvesting pigments is reported. The theory provides an explanation for the picosecond absorbance difference spectra, the induced absorption anisotropy decay, the anomalously high bleaching valné, as well as for the fluorescence spectra, kinetics and depolarizatio
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

9460. Spectral propertíes and CO2 exchange of tomato fruits

Creator:
Czarnowski, M. and Starzecki, W.
Format:
print
Type:
model:internalpart and TEXT
Language:
Multiple languages
Description:
Spectral absoiptance of greenhouse tomato (Lycopersicon esculentum Milí.) canopy (sunny day, LAI = 2.54) varied between 87-89 %. Absoiptance of smáli tomato fruits was 77 % of PAR energy (spectral reflectance was 22 % and transmittance 1 %). The difíusion resistance to COj of the parenchyma extemal layer with epidermis in smáli fruits reached 25 s cm‘i and in large green fruits 75 s cm-i. At the atmospheric CO2 concentration (330 cm^ m*^) and the quantum flux density of PAR 800 pmol m'2 s'* the steady statě CO2 evolution rate was found to be slightly below its compensation value [-0.06 mg(C02) kg-i(d.m.) s-i]. The net photosynthetic rate in smail tomato fruits was 0.3 mg(C02) kg-i(d.m.) s'*, whereas in a large green tomato it reached 0.16 mg(C02) kg-i(d.m.) s’T Intemal CO2 concentration in smáli tomato frnits by the light was 2 300 cm3(C02) m-3 and in the dark 2 900 cm3(C02) m*3. Even under the optimal irradiance CO2 difíusion proceeded always from fruits to the environment.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

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