Salinity Dependent Resistance of Dunaliella parva against Extreme Temperatures I. Salinity and Thermoresistance

Gimmler, H.; Kühnl, E.M.; Carl, G. Clifford

doi:10.1016/s0044-328x(78)80175-5

Cited by 19 publications

(8 citation statements)

References 25 publications

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“…However sugars can increase the heat stability of isolated spinach thylakoid membranes (Santarius, 1973). In the marine unicellular alga Dunaliella parva, 1 M glycerol increases the heat stability of electron transport m isolated thylakoid membranes by up to 5 o C (Gimmler et al, 1978). This effect is similar in magnitude to the present experiments with isolated enzymes.…”

Section: The Physiological Significance Of Enhanced Heat Stabilitysupporting

confidence: 84%

Stress metabolites and their role in coastal plants

Smirnoff

Stewart

1985

Vegetatio

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The stress metabolites proline, glycine betaine and sorbitol were accumulated in the leaves of some angiosperms from sand dunes and shingle. Chloride, where it was measured, was not accumulated to high concentrations in leaves suggesting that these soils are not saline. Sand dunes and shingle soils have low water-holding capacity, so it is possible that solute accumulation was a response to drought which could be of adaptive significance. In sand dunes low water availability could be associated with increased leaf temperatures because of reduced transpiration rates and high soil temperatures. The role of stress metabolites in heat tolerance was considered. Proline, betaine, sorbitol and mannitol increased the heat stability of glutamine synthetase (GS) and glutamate: oxaloacetate aminotransferase from Ammophila arenaria. For GS the effect increased with solute concentration. The polyols were more effective at high temperatures. The heat stability of GS from the moss Tortula ruraliformis and the brown alga Fucus vesiculosus was increased by mannitol.

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Section: The Physiological Significance Of Enhanced Heat Stabilitysupporting

confidence: 84%

Stress metabolites and their role in coastal plants

Smirnoff

Stewart

1985

Vegetatio

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“…A previous study (9) of the temperature resistance of a variety of properties of Dunaliella parva, such as CO2 fixation, photosynthetic activities of isolated thylakoids, and K+ efflux from the cells, indicated that cells grown at high salt concentration were significantly more thermoresistant than those grown at lower concentration. Thus, the change in property which is responsible for the loss of the ability to retain glycerol may be more specific than that which leads to the inactivation of the other properties studied.…”

Section: Resultsmentioning

confidence: 96%

Effect of Temperature on Glycerol Retention in the Halotolerant Algae Dunaliella and Asteromonas

Wegmann¹,

Ben‐Amotz²,

Avron³

1980

Plant Physiol.

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Algae of the genera DunalieUa and Asteromonas can maintain extremely high concentration gradients (>104) of glycerol between the intracellular space and the medium. This unique ability is highly temperature-dependent. Treating the algae for several minutes at temperatures exceeding 60 C causes complete release of all the internally held glycerol; 50% release occurs around 50 C, but essentially none is released below 40 C. A similar behavior was observed in several species of Dwnaliella, and one of Asteromonas and is independent of the salt concentration of the medium. The underlying mechanism may involve a temperature-dependent conformational transition of a component of the cellular membrane which is essential for glycerol impermeability.

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“…Comparison of these studies is difficult as measurements of the thermal stability of chloroplasts and mitochondria have been performed with different plant material and under variant conditions. Moreover, there are hints that other cellular membranes such as the plasmalemma also are susceptible to high temperature stress (10,19). Thus, heat damage to energy-conserving processes in situ may result from a heatinduced loss of cellular compartmentation.…”

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confidence: 99%

Effects of High-Temperature Stress on Various Biomembranes of Leaf Cells In Situ and In Vitro

Thebud

Santarius²

1982

Plant Physiol.

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The sensitivity of photosynthetic and respiratory functions to supraoptimal temperature stress was compared after heating of leaves, protoplasts and membrane systems of spinach (Spinacia okracea L. cv. Monatol) and lettuce ( Valerianella locusta IL.1 Betcke) in situ and in vitro.After heating of whole leaves or protoplasts, endogenous respiration was not or only slightly affected at temperatures which caused a marked decrease of photosynthesis. This was manifested when mitochondria and thylakoids were isolated from heat-treated leaves. In the presence of exogenous substrates, mitochondrial electron transport and phosphorylation were even somewhat stimulated compared to the controls.Inactivation of net CO2 uptake of whole leaves following heat stress and of the photochemical activities of chloroplast membranes isolated from heat-treated leaves of the same origin occurred nearly simultaneously. In protoplasts, photosynthesis was inactivated at temperatures far below those which caused drastic changes in the integrity of the tonoplast and the plasmalemma. This indicates that damage occurring within the chloroplasts rather than alterations in the compartmentation of the cell is responsible for the high sensitivity of photosynthesis to supraoptimal temperature stress.Mitochondria and thykaloids isolated from the same preparation of intact leaves under comparable conditions and subjected to heat treatment in vitro, however, were inactivated nearly in the same temperature range. Thus, mitochondria are much more stable within their cytoplasmic environment.Cellular membranes are thought to be primarily involved in injury caused in plant cells by extreme temperatures. The question arises as to how various membrane systems differ in thermolability. In green tissues, respiration is more heat-stable than photosynthesis (1,3,14,15,17). Investigations with isolated membrane systems have shown that heat treatment of chloroplasts results primarily in an inactivation of the photochemical reactions in the highly thermolabile thylakoid membranes (4,23,24). On the other hand, isolated plant mitochondria also became inactivated even by mild heat treatment (5,13,25). Comparison of these studies is difficult as measurements of the thermal stability of chloroplasts and mitochondria have been performed with different plant material and under variant conditions. Moreover, there are hints that other cellular membranes such as the plasmalemma also are susceptible to high temperature stress (10,19). Thus, heat damage to energy-conserving processes in situ may result from a heatinduced loss of cellular compartmentation.The effect of supraoptimal temperatures on respiratory and photosynthetic functions of spinach leaves has been investigated more thoroughly in the present study. The overall processes of net photosynthesis and respiration of whole leaves were compared after they had been subjected to various temperatures. To study alterations in cellular membranes after heating in situ, intact leaves were exposed to various elevated tem...

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Salinity Dependent Resistance of Dunaliella parva against Extreme Temperatures I. Salinity and Thermoresistance

Cited by 19 publications

References 25 publications

Stress metabolites and their role in coastal plants

Stress metabolites and their role in coastal plants

Effect of Temperature on Glycerol Retention in the Halotolerant Algae Dunaliella and Asteromonas

Effects of High-Temperature Stress on Various Biomembranes of Leaf Cells In Situ and In Vitro

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