scholarly journals Differences in lipid homeostasis and membrane lipid unsaturation confer differential tolerance to low temperatures in two Cycas species

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Yanling Zheng ◽  
Yongqiong Yang ◽  
Meng Wang ◽  
Shijun Hu ◽  
Jianrong Wu ◽  
...  
Keyword(s):  
Chlorophyll Fluorescence ◽  
Lipid Metabolism ◽  
Low Temperature ◽  
Low Temperatures ◽  
Photosynthetic Activity ◽  
Membrane Lipids ◽  
Chlorophyll Fluorescence Parameters ◽  
Fluorescence Parameters ◽  
Temperature Exposure ◽  
Low Temperature Exposure

Abstract Background C. panzhihuaensis is more tolerant to freezing than C. bifida but the mechanisms underlying the different freezing tolerance are unclear. Photosynthesis is one of the most temperature-sensitive processes. Lipids play important roles in membrane structure, signal transduction and energy storage, which are closely related to the stress responses of plants. In this study, the chlorophyll fluorescence parameters and lipid profiles of the two species were characterized to explore the changes in photosynthetic activity and lipid metabolism following low-temperature exposure and subsequent recovery. Results Photosynthetic activity significantly decreased in C. bifida with the decrease of temperatures and reached zero after recovery. Photosynthetic activity, however, was little affected in C. panzhihuaensis. The lipid composition of C. bifida was more affected by cold and freezing treatments than C. panzhihuaensis. Compared with the control, the proportions of all the lipid categories recovered to the original level in C. panzhihuaensis, but the proportions of most lipid categories changed significantly in C. bifida after 3 d of recovery. In particular, the glycerophospholipids and prenol lipids degraded severely during the recovery period of C. bifida. Changes in acyl chain length and double bond index (DBI) occurred in more lipid classes immediately after low-temperature exposure in C. panzhihuaensis compare with those in C. bifida. DBI of the total main membrane lipids of C. panzhihuaensis was significantly higher than that of C. bifida following all temperature treatments. Conclusions The results of chlorophyll fluorescence parameters confirmed that the freezing tolerance of C. panzhihuaensis was greater than that of C. bifida. The lipid metabolism of the two species had differential responses to low temperatures. The homeostasis and plastic adjustment of lipid metabolism and the higher level of DBI of the main membrane lipids may contribute to the greater tolerance of C. panzhihuaensis to low temperatures.

scholarly journals The Differential Responses of Chlorophyll Fluorescence Parameters and Lipid Metabolism to Low Temperature between Cycas Bifida and C. panzhihuaensis

2020 ◽  
Author(s):  
Yanling Zheng ◽  
Meng Wang ◽  
Shijun Hu ◽  
Jianrong Wu ◽  
Zhixiang Yu
Keyword(s):  
Chlorophyll Fluorescence ◽  
Lipid Metabolism ◽  
Low Temperature ◽  
Freezing Tolerance ◽  
Low Temperatures ◽  
Photosynthetic Activity ◽  
Membrane Lipids ◽  
Chlorophyll Fluorescence Parameters ◽  
Fluorescence Parameters ◽  
Differential Responses

Abstract Background: Our previous work showed that freezing tolerance of Cycas panzhihuaensis was higher than that of C. bifida. However, the mechanisms underlying the differential freezing tolerance of the two species is not clear. Photosynthesis is one of the most temperature-sensitive processes. Lipids play important roles in membrane structure, signal transduction and energy storage which are closely related to stress response of plants. Hence, the chlorophyll fluorescence parameters and lipid profiles of the two species were characterized to explore the dynamic changes of photosynthetic activity and lipid metabolism following low temperature and subsequent recovery. Results: The photosynthetic activity decreased significantly with the decrease of temperatures in C. bifida, reaching to zero after recovery, which however, was little affected in C. panzhihuaensis. Lipid composition of C. bifida was more affected by cold and freezing treatments than C. panzhihuaensis. Compared to the control, the proportions of all the lipid categories recovered to the original level for C. panzhihuaensis but those of most lipid categories changed significantly for C. bifida after 3 d of recovery. Particularly, the glycerophospholipids and prenol lipids of C. bifida degraded severely during recovery period for C. bifida. The changes of acyl chain length and double bond index (DBI) occurred in more lipid classes immediately after low temperatures in C. panzhihuaensis than those in C. bifida. DBI of the total main membrane lipids of C. panzhihuaensis was significantly higher than that of C. bifida following all the treatments. Conclusions: The results of chlorophyll fluorescence parameters confirmed that the freezing tolerance of C. panzhihuaensis was higher than that of C. bifida. The lipid metabolism of the two species had differential responses to low temperatures. The homeostasis and plastic adjustment of lipid metabolism and the higher level of DBI of the main membrane lipids might contribute to the higher tolerance of C. panzhihuaensis to low temperature.

scholarly journals Limitation of photosynthetic processes in photosystem II in alpine mosses exposed to low temperatures: Response of chlorophyll fluorescence parameters

2018 ◽  
Vol 8 (2) ◽  
pp. 218-229 ◽  
Author(s):  
Yeray Folgar Cameán ◽  
Miloš Barták
Keyword(s):  
Chlorophyll Fluorescence ◽  
Low Temperature ◽  
Photosystem Ii ◽  
Temperature Stress ◽  
Low Temperature Stress ◽  
Ps Ii ◽  
Chlorophyll Fluorescence Parameters ◽  
Fluorescence Parameters ◽  
Fluorescence Measurements ◽  
Sphagnum Girgensohnii

In this study, we evaluated the effects of low and sub-zero temperature on the fast chlorophyll fluorescence transient (OJIP) and OJIP-derived parameters in 4 different mosses: Sphagnum girgensohnii, Polytrichum formosum, Hylocomium splendens and Pleurozium schreberi. The low temperature stress was applied on the mosses for 90 min. at 3 different temperatures (5°C, -1°C and -10°C). To investigate the effects of this stress on the functioning of photosystem II (PS II), the chlorophyll fluorescence measurements were taken at control temperature (22°C) and, after a 90 min. acclimation period, at each experimental temperature. The shape of OJIP curves and chlorophyll fluorescence parameters were found temperature-dependent in all the species. The mosses differed in their sensitivity to the stress but general trends in response to low temperature were similar. The results support the idea that S. girgensohnii is less resistant to low temperature stress than the other species. We were also interested in the K and L steps in OJIPs, representing different disorders caused by low temperature. The K-step was seen in P. formosum and P. schreberi and the L-step in H. splendens and S. girgensohnii.

scholarly journals Is cold the new hot in sudden unexpected death in epilepsy? Effect of low temperature on heart rate of rats with epilepsy

2008 ◽  
Vol 66 (4) ◽  
pp. 848-852 ◽  
Author(s):  
Eliza Y.F. Sonoda ◽  
Diego B. Colugnati ◽  
Carla A. Scorza ◽  
Ricardo M. Arida ◽  
Aline P. Pansani ◽  
...  
Keyword(s):  
Risk Factors ◽  
Heart Rate ◽  
Low Temperature ◽  
Low Temperatures ◽  
Refractory Epilepsy ◽  
Sudden Unexpected Death ◽  
Unexpected Death ◽  
Temperature Exposure ◽  
Low Temperature Exposure ◽  
Related Mortality

Sudden unexpected death in epilepsy (SUDEP) is the commonest cause of seizure-related mortality in people with refractory epilepsy. Several risk factors for SUDEP are described; however, the importance of including low temperatures as risk factor for SUDEP was never explored. Based on this, the aim of this study was to evaluate the heart rate of rats with epilepsy during low temperature exposure. Our results showed that low temperature clearly increased the heart rate of rats with epilepsy. Taken together, we concluded that exposure to low temperatures could be considered important risk factors from cardiovascular abnormalities and hence sudden cardiac death in epilepsy.

An Analysis of Cell Freezing and Dehydration

1970 ◽  
Vol 92 (3) ◽  
pp. 393-398 ◽  
Author(s):  
G. R. Ling ◽  
C. L. Tien
Keyword(s):  
Differential Equation ◽  
Low Temperature ◽  
Cooling Rate ◽  
Low Temperatures ◽  
Living Cells ◽  
Cell Parameters ◽  
Theoretical Predictions ◽  
Cell Dehydration ◽  
Temperature Exposure ◽  
Low Temperature Exposure

A quantitative picture of the effect of low-temperature exposure on the survival of living cells is presented through discussion of solutions to a differential equation relating the volume of intracellular water to the temperature, the cooling rate, and various cell parameters. It is found that for a given cell, a single parameter which depends on the cooling rate governs the behavior of the cell when it is exposed to low temperatures. The analysis develops relationships between solutions to the differential equation and the phenomena affecting cell survival, namely, intracellular freezing and cell dehydration. Theoretical predictions are found to agree well with existing experimental observations.

Short-term responses of primary processes in PS II to low temperature are sensitively indicated by fast chlorophyll fluorescence kinetics in Antarctic lichen Dermatocarpon polyphyllizum

2017 ◽  
Vol 7 (1) ◽  
pp. 74-82 ◽  
Author(s):  
Michaela Marečková ◽  
Miloš Barták
Keyword(s):  
Chlorophyll Fluorescence ◽  
Low Temperature ◽  
High Energy ◽  
Temperature Decrease ◽  
Temperature Dependent ◽  
Dark Light ◽  
Ps Ii ◽  
Chlorophyll Fluorescence Parameters ◽  
Fluorescence Parameters ◽  
Quinone Acceptor

In this study, we investigated the effects of low temperature on the fast chlorophyll fluo-rescence transient (OJIP) and OJIP-derived parameters in chlorolichen Dermatocarpon polyphyllizum expossed to a gradually decreasing temperature (22°C, 18°C, 14°C, 12°C, 10°C, 7°C and 4°C). The segments of lichen thalli were exposed to a certain temperature either in dark- and light-adapted state for 10 minutes in order to evaluate the effects on chlorophyll fluorescence parameters. The initial photochemical phase of the transient (O-J) due to reduction of the primary quinone acceptor (QA) was found temperature dependent. The K-step was apparent for the samples measured at the temperature above 12°C, but not below 10oC in light-adapted lichen thalli. With the thallus temperature decrease, majority of the chlorophyll fluorescence parameters derived from OJIP (ET0/RC, Psi_0, and DI0/RC) showed no change in light-adapted samples but a decrease in dark-adapted samples. The effects of dark- / light-adaptation of the lichen samples on the OJIP and OJIP-derived parameters was attributed to the differences in production/utilization of high-energy products of primary photochemical processes of photosynthesis in dark- and light-adapted state, respectively. The other parameters (ABS/RC, TR0/RC) showed a decrease with thallus temperature decrease both in light- and dark-adapted samples. The results suggest that fast chlorophyll fluorescence trasient is an useful tool to investigate temperature-dependent changes in photosystem II in chlorolichens, their photobionts, respectively.

scholarly journals Tomato Seedling Growth, Earliness, Yield, and Quality following Pretransplant Nutritional Conditioning and Low Temperatures

1991 ◽  
Vol 116 (3) ◽  
pp. 421-425 ◽  
Author(s):  
Regina R. Melton ◽  
Robert J. Dufault
Keyword(s):  
Low Temperature ◽  
Seedling Growth ◽  
Low Temperatures ◽  
Temperature Treatment ◽  
Tomato Seedling ◽  
Tomato Seedlings ◽  
Low Temperature Treatment ◽  
Yield And Quality ◽  
Temperature Exposure ◽  
Low Temperature Exposure

`Sunny' tomato (Lycopersicon esculentum Mill.) seedlings were pretransplant nutritionally conditioned (PNC) in 1988 and 1989 with factorial combinations of N from 100 to 300 mg·liter-1 and P from 10 to 70 mg·liter-1. In 1988, all conditioned seedlings were exposed to 12 hours of 2C for eight consecutive nights before transplanting. In 1989, half of the conditioned plants were exposed to a low-temperature treatment of 8 days with 12-hour nights at 2C and 12-hour days in a warm greenhouse (19C/26C, night/day). In both years, as N PNC increased to 200 mg·liter-1, seedling growth increased. Increasing P PNC from 10 to 40 mg·liter-1 increased seedling growth, but only in 1988. In both years, P PNC did not affect yields. Low-temperature exposure in 1989 decreased seedling growth in comparison to those held in a warm greenhouse (19C/26C, day/night). In 1988, first harvest yields were not affected by N PNC; however, in 1989, as N increased to 200 mg·liter-1, early yields increased. In 1988, total yields increased wit h N PNC from 100 to 200 mg·liter-1 and in 1989 with N at 50 to 100 mg·liter-1 with no further increases from 100 to 200 mg·liter-1. Low-temperature exposure had no effect on earliness, yield, or quality. A PNC regime combining at least 200 mg N/liter and up to 10 mg P/liter should be used to nutritionally condition `Sunny' tomato seedlings to enhance yield.

Induced bolting and anthesis in sugar beet and the effect of selection of physiological types

1946 ◽  
Vol 36 (3) ◽  
pp. 167-183 ◽  
Author(s):  
G. D. H. Bell
Keyword(s):  
Low Temperature ◽  
Sugar Beet ◽  
Low Temperatures ◽  
Continuous Light ◽  
Light Treatment ◽  
Seedling Stage ◽  
Temperature Exposure ◽  
Different Strains ◽  
Low Temperature Exposure ◽  
Selection Of

1. The effect of low-temperature and continuous-light treatment of seedlings of certain sugar beet strains in the isolation of distinct physiological types is described. The progenies of individual plants and bulk samples of different anthesis dates show some difference in the proportions of early and late plants, when these progenies are similarly exposed to low temperatures and continuous light in the seedling.2. Different treatments of progenies in relation to light treatment in the seedling stage result in distinct behaviour with regard to anthesis date and the number of plants reaching the stage of anthesis.3. The comparative resistance to bolting from a field sowing of seed obtained from plants which ripened seed after continuous light treatment of the seedlings is noted. This was so in spite of the fact that only 66% of the plants had reached anthesis as a result of the treatment, and the seed was obtained from the most rapidly bolting plants.4. Light and low temperature exposure of seedlings is effective in two different strains for isolating bolting-resistant types as measured directly from the seed of these bolting-resistant plants and selected progenies from these plants. Differences in the field germination and establishment from very early sowings were discernible in the progenies.

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