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Start Over Subject cold stress

1. Cold-activated growth of rat brown adipose tissue in the neonatal period

Creator:
Drahota, Z. and Hahn, P.
Type:
article, model:article, and TEXT
Subject:
brown adipose tissue, newborn rats, and cold stress
Language:
English
Description:
Repeated exposure of newborn rats to a short-term cold load between day 10 and 30 after birth stimulates the physiological growth rate of the brown adipose tissue. This indicates that in the neonatal period the brown adipose tissue has no reserve thermogenic capacity to compensate an additional cold load and therefore the rate of tissue growth must be activated.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2. Influence of low temperatures on the growth and photosynthetic activity of industrial chicory, Cichorium intybus L. partim

Creator:
Devacht, S., Lootens, P., Roldán-Ruiz, I., Carlier, L., Baert, J., van Waes, J., and van Bockstaele, E.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
chilling, chlorophyll a fluorescence, cold stress, early vigour, photoinhibition, and photosynthesis
Language:
Multiple languages
Description:
The cold stress effect on early vigour and photosynthesis efficiency was evaluated for five industrial chicory varieties with contrasting early vigour. The relationships between the growth and physiological parameters were assessed. The varieties were examined at three growth temperatures: 16 (reference), 8 (intermediate) and 4 °C (stress). The effect was measured using physiological processes (growth, photosynthesis, chlorophyll a fluorescence), and pigment content. The analysis of the measured growth parameters (dry leaf and root mass, and leaf area) indicated that temperature had a significant effect on the varieties, but the overall reaction of the varieties was similar with lowering temperatures. The photosynthesis and chlorophyll a fluorescence measurements revealed significant changes for the photosynthesis (maximum net photosynthesis, quantum efficiency, light compensation point and dark respiration) and chlorophyll a fluorescence parameters (photochemical and non-photochemical quenching) with lowering temperatures for Hera and Eva, two extremes in youth growth. No significant differences could be found between the extremes for the different temperatures. The pigment content analysis revealed significant differences at 4 °C in contrast to 16 and 8 °C, especially for the xanthophyll/carotenoid pool, suggesting a protective role. Subsequently, the relationship between the physiological processes was evaluated using principal component analysis. At 4 °C, 2 principal components were detected with high discriminating power for the varieties and similar classification of the varieties as determined in the growth analysis. This provides a preview on the possible relationships between photosynthesis and growth for industrial chicory at low temperatures. and S. Devacht ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

3. Low temperature stress modifies the photochemical efficiency of a tropical tree species Hevea brasiliensis: effects of varying concentration of CO2 and photon flux density

Creator:
Alam, B., Nair, D. B., and Jacob, J.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
chlorophyll fluorescence, cold stress, partitioning of photosynthetic electron transport, photochemical efficiency, and photoinhibition
Language:
Multiple languages
Description:
Two clones of Hevea brasiliensis (RRII 105 and PB 235) were grown for one year in two distinct agroclimatic locations (warmer and colder, W and C) in peninsular India. We simultaneously measured gas exchange and chlorophyll (Chl) fluorescence on fully mature intact leaves at different photosynthetic photon flux densities (PPFDs) and ambient CO2 concentrations (Ca) and at constant ambient O2 concentration (21 %). Net photosynthetic rate (PN), apparent quantum yield for CO2 assimilation (Φc), in vivo carboxylation efficiency (CE), and photosystem 2 quantum yield (ΦPS2) were low in plants grown in C climate and these reductions were more predominant in RRII 105 than in PB 235 which was also reflected in their growth. We estimated in these clones the partitioning of photosynthetic electrons between CO2 reduction (JA) and processes other than CO2 reduction (J*) at low and high PPFDs and Ca. At high Ca (700 µmol mol-1) most of the photosynthetic electrons were used for CO2 assimilation and negligible amount went for other processes when PPFD was low (200-300 µmol m-2 s-1) both in the C and W climates. But at high PPFD (900-1 100 µmol m-2 s-1), J* was appreciably high even at a high Ca. Hence at normal ambient Ca and high irradiance, electrons can be generated in the photosynthetic apparatus far in excess of what can be safely utilised for photosynthetic CO2 reduction. However, at high Ca there was increased diversion of electrons to photosynthetic CO2 reduction which resulted in improved photosynthetic parameters even in plants grown in C climate. and B. Alam, D. B. Nair, J. Jacob.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

4. Reduction of photosynthetic apparatus plays a key role in survival of the microalga Haematococcus pluvialis (Chlorophyceae) at freezing temperatures

Creator:
Chekanov, K., Vasilieva, S., Solovchenko, A., and Lobakova, E.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
fotosyntéza, photosynthesis, cold stress, Haematococcys pluvialis, stress tolerance, 2, and 581
Language:
Multiple languages
Description:
The microalga Haematococcus pluvialis is a biotechnologically important microorganism producing a ketocarotenoid astaxanthin. Haematococcus exists either as metabolically active vegetative cells with a high chlorophyll content or astaxanthin-rich haematocysts (aplanospores). This microalga featuring outstanding tolerance to a wide range of adverse conditions is a highly suitable model for studies of freezing tolerance in phototrophs. The retention of H. pluvialis cell viability after freezing-thawing is ascribed to elevated antioxidant enzyme activity and high ketocarotenoid content. However, we report that only haematocysts characterized by a lower photosynthetic activity were resistant to freezing-thawing even without cryoprotectant addition. The key factors of haematocyst freezing tolerance were assumed to be a low water content, rigid cell walls, reduction of the membranous structures, photosynthesis downregulation, and low chlorophyll content. Collectively, viability of Haematoccus after freezing-thawing can be improved by forcing the transition of vegetative cells to freeze-tolerant haematocysts before freezing., K. Chekanov, S. Vasilieva, A. Solovchenko, E. Lobakova., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public