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1565. Adaptation of the heart to hypertension is associated with maladaptive gap junction connexin-43 remodeling

Creator:
Marcela Fialová, Katarína Dlugošová, Ľudmila Okruhlicová, Kristek, F., Manoach, M., and Narcisa Tribulová
Format:
print, bez média, and svazek
Type:
article, články, model:article, and TEXT
Subject:
Fyziologie člověka a srovnávací fyziologie, fyziologie, hypertenze, srdeční arytmie, physiology, hypertension, cardiac arrhythmia, gap junction remodeling, connexin-43, malignant arrhythmias, 14, and 612
Language:
English
Description:
We hypothesized that hypertension-related myocardial remodeling characterized by hypertrophy and fibrosis might be accompanied by cell-to-cell gap junction alterations that may account for increased arrhythmogenesis. Intercellular junctions and expression of gap junction protein connexin-43 were analyzed in rat heart tissues from both spontaneous (SHR) and L-NAME model of hypertension. Isolated heart preparation was used to examine susceptibility of the heart to lethal ventricular fibrillation induced by low potassium perfusion. Ultrastructure observation revealed enhanced neoformation of side-to-side type while internalization of end-to-end type (intercalated disc-related) of gap junctions prevailed in the myocardium of rats suffering from either spontaneous or L-NAME-induced hypertension. In parallel, immunolabeling showed increased number of connexin-43 positive gap junctions in lateral cell membrane surfaces, particularly in SHR. Besides, focal loss of immunopositive signal was observed more frequently in hearts of rats treated with L-NAME. There was a significantly higher incidence of hypokalemia-induced ventricular fibrillation in hypertensive compared to normotensive rat hearts. We conclude that adaptation of the heart to hypertension-induced mechanical overload results in maladaptive gap junction remodeling that consequently promotes development of fatal arrhythmias., M. Fialová, K. Dlugošová, L. Okrouhlicová, F. Kristek, M. Manoach, N. Tribulová., and Obsahuje bibliografii a biblioigrafické údaje
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1566. Adaptation strategies of two leaf cohorts of Prosopis juliflora produced in spring and monsoon

Creator:
Shirke, P. A., Pathre, U. V., and Sane, P. V.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
asimilace uhlíku, carbon assimilation, carboxylation efficiency, dark respiration rate, quantum efficiency, tree photosynthesis, water-use efficiency, 2, and 581
Language:
Multiple languages
Description:
Prosopis juliflora is an invasive leguminous tree species growing profusely under wide environmental conditions. Primary objective of this study was to investigate adaptation strategies evolved to deal with wide environmental conditions during different seasons. P. juliflora adapts through a production of leaves in two seasons, namely, the spring (the first cohort) and monsoon (the second cohort) with differing but optimal physiological characteristics for growth in respective seasons. Our studies show that the first cohort of leaves exhibit maximum carbon fixation under moderate temperatures and a wide range of PPFD. However, these leaves are sensitive to high leaf-to-air-vapor pressure deficit (VPD) occurring at high temperatures in summer resulting in senescence. While the second cohort of leaves produced during monsoon showed maximum carbon fixation at high irradiance and temperatures with low VPD, it is sensitive to low temperatures causing senescence in winter., P. A. Shirke, U. V. Pathre, P. V. Sane., and Obsahuje bibliografické odkazy
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1567. Adaptive output feedback stabilization for nonlinear systems with unknown polynomial-of-output growth rate and sensor uncertainty

Creator:
Shen, Yanjun and Lin, Lei
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
adaptive stabilization, polynomial-of-output growth rate, measurement sensitivity, output feedback, and observer
Language:
English
Description:
In this paper, the problem of adaptive output feedback stabilization is investigated for a class of nonlinear systems with sensor uncertainty in measured output and a growth rate of polynomial-of-output multiplying an unknown constant in the nonlinear terms. By developing a dual-domination approach, an adaptive observer and an output feedback controller are designed to stabilize the nonlinear system by directly utilizing the measured output with uncertainty. Besides, two types of extension are made such that the proposed methods of adaptive output feedback stabilization can be applied for nonlinear systems with a large range of sensor uncertainty. Finally, numerical simulations are provided to illustrate the correctness of the theoretical results.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1568. Adaptive photosynthetic and physiological responses to drought and rewatering in triploid Populus populations

Creator:
Liao, T., Wang, Y., Xu, C. P., Li, Y., and Kang, X. Y.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
topol, populace (biologie), poplar, population (biology), chlorofylová fluorescence, výměna plynu, malondialdehyd, stomatální omezení, deficit vody, sucho, chlorophyll fluorescence, gas exchange, malondialdehyde, stomatal limitation, water deficit, drought, 2, and 581
Language:
Multiple languages
Description:
Cuttings of Populus cathayana Rehd, originating from three triploid and one diploid populations with the same parents but different gamete origins, were used to examine physiological responses to drought stress and rewatering by exposure to three progressive water regimes. Progressive drought stress significantly decreased the leaf relative water content (RWC), photosynthesis, and chlorophyll fluorescence parameters, and increased the relative electrolyte leakage, malondialdehyde (MDA), free proline (Pro), and antioxidant enzymes, such as superoxide dismutase, peroxidase, and catalase, in the four populations evaluated. However, compared to the diploid population, triploid populations showed lower relative electrolyte leakage and MDA, higher RWC and Pro content, and more efficient photosynthesis and antioxidant systems under the same water regime. Our data indicated that triploid populations possessed more efficient protective mechanisms than that of diploid population with gradually increasing drought stress. Moreover, some triploid genotypes were less tolerant to water stress than that of diploids due to large intrapopulation overlap., T. Liao, Y. Wang, C. P. Xu, Y. Li, X. Y. Kang., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1569. Adaptive photosynthetic strategies of the invasive plant Sphagneticola trilobata and its hybrid to a low-light environment

Creator:
Ke, W. Q., Pan, Y. R., Chen, L. H., Huang, J. D., Zhang, J. J., Long, X. Y., Cai, M. L., and Peng, C. L.
Format:
počítač and online zdroj
Type:
model:article and TEXT
Subject:
growth strategy, hybridization, low light, photosynthesis, and plant invasion
Language:
Multiple languages
Description:
In stressful environments, invasive plants acclimate more efficiently than native plants and hybridization mainly contributes to this process. We examined changes in the morphological characteristics, photosynthetic characteristics, and antioxidant capacity of Sphagneticola trilobata and its hybrids in a low-light environment to explore their invasiveness, with Sphagneticola calendulacea serving as the control. The morphological plasticity of S. trilobata was not dominant, the maximal photochemical efficiency of PSII, actual quantum yield of PSII, and electron transport rate of PSⅡ increased and nonphotochemical quenching decreased, while S. calendulacea and the hybrid produced opposite results. S. trilobata showed fewer spots stained for reactive oxygen species in tissues, with an increase in superoxide dismutase activity. Although S. trilobata is a heliophilous plant, we found that the shade tolerance of S. trilobata and the hybrid were stronger than that of S. calendulacea, which may be one important mechanism of invasion.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1570. Adaptive photosynthetic strategies of the Mediterranean maquis species according to their origin

Creator:
Gratani, L. and Varone, L.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
Arbutus, Cistus, drought period, Erica, Phillyrea, Pistacia, Quercus, recovery capacity, Rosmarinus, and stomatal conductance
Language:
Multiple languages
Description:
In consideration of their origin the adaptive strategies of the evergreen species of the Mediterranean maquis were analysed. Rosmarinus officinalis L., Erica arborea L., and Erica multiflora L. had the lowest net photosynthetic rate (PN) in the favourable period [7.8±0.6 μmol(CO2) m-2s-1, mean value], the highest PN decrease (on an average 86 % of the maximum) but the highest recovery capacity (>70 % of the maximum) at the first rainfall in September. Cistus incanus L. and Arbutus unedo L. had the highest PN during the favourable period [15.5±5.2 μmol(CO2) m-2s-1, mean value], 79 % decrease during drought, and a lower recovery capacity (on an average 54 %). Quercus ilex L., Phillyrea latifolia L., and Pistacia lentiscus L. had an intermediate PN in the favourable period [9.2±1.3 μmol(CO2) m-2s-1, mean value], a lower reduction during drought (on an average 63 %), and a range from 62 % (Q. ilex and P. latifolia) to 39 % (P. lentiscus) of recovery capacity. The Mediterranean species had higher decrease in PN and stomatal conductance during drought and a higher recovery capacity than the pre-Mediterranean species. Among the pre-Mediterranean species, P. latifoliahad the best adaptation to long drought periods also by its higher leaf mass per area (LMA) which lowered leaf temperature thus decreasing transpiration rate during drought. Moreover, its leaf longevity determined a more stable leaf biomass during the year. Among the Mediteranean species, R. officinalis was the best adapted species to short drought periods by its ability to rapidly recover. Nevertheless, R. officinalis had the lowest tolerance to high temperatures by its PN dropping below half its maximum value when leaf temperature was over 33.6°C. R. officinalismay be used as a bioindicator species of global change. and L. Gratani, L. Varone.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

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