Body fluid responses of heat-tolerant and intolerant men to work in a hot wet environment

1976 ◽  
Vol 40 (1) ◽  
pp. 55-59 ◽  
Author(s):  
L. C. Senay ◽  
R. Kok
Keyword(s):  
Fluid Dynamics ◽  
Oxygen Consumption ◽  
South African ◽  
Heat Tolerance ◽  
Body Fluid ◽  
Large Population ◽  
Work Period ◽  
Blood Constituent ◽  
Heat Tolerant ◽  
Capillary Walls

Acclimatization to heat before proceeding underground is a requirement for each South African mine laborer. Certain individuals among this large population cannot be acclimatized to heat (33.3 degrees C db, 31.7 degrees C wb) and are classified as heat intolerant. In this study certain body fluid responses to heat and work were compared between a group of 19 heat-tolerant (HT) and of 15 heat-intolerant (HI) subjects. To the factors known to affect heat tolerance such as age, weight, and oxygen consumption must now be added differences in body fluid responses. The HI group of subjects failed to hemodilute to the same degree as the HT group though working at the same relative work loads (30% and 50% VO2 max). As the 4-h work period (33.3 degrees C db, 31.7 degrees C wb) continued, the HI group did not maintain hemodilution in spite of the lower absolute work loads, sweat rates, and water deficits suffered by this group. From analysis of blood constituent changes it was suggested that the reason for the differences noted in body fluid dynamics concerned plasma protein equilibrium across capillary walls as well as the protein population of interstitial spaces.

scholarly journals Heat-tolerant hot pepper exhibits constant photosynthesis via increased transpiration rate, high proline content and fast recovery in heat stress condition

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sherzod Nigmatullayevich Rajametov ◽  
Eun Young Yang ◽  
Myeong Cheoul Cho ◽  
Soo Young Chae ◽  
Hyo Bong Jeong ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Heat Stress ◽  
Heat Tolerance ◽  
Transpiration Rate ◽  
Stress Condition ◽  
Proline Content ◽  
Hot Pepper ◽  
Fast Recovery ◽  
Heat Stress Condition ◽  
Heat Tolerant

AbstractUnderstanding the mechanism for heat tolerance is important for the hot pepper breeding program to develop heat-tolerant cultivars in changing climate. This study was conducted to investigate physiological and biochemical parameters related to heat tolerance and to determine leaf heat damage levels critical for selecting heat-tolerant genotypes. Seedlings of two commercial cultivars, heat-tolerant ‘NW Bigarim’ (NB) and susceptible ‘Chyung Yang’ (CY), were grown in 42 °C for ten days. Photosynthesis, electrolyte conductivity, proline content were measured among seedlings during heat treatment. Photosynthetic rate was significantly reduced in ‘CY’ but not in ‘NB’ seedlings in 42 °C. Stomatal conductivity and transpiration rate was significantly higher in ‘NB’ than ‘CY’. Proline content was also significantly higher in ‘NB’. After heat treatment, leaf heat damages were determined as 0, 25, 50 and 75% and plants with different leaf heat damages were moved to a glasshouse (30–32/22–24 °C in day/night). The growth and developmental parameters were investigated until 70 days. ‘NB’ was significantly affected by leaf heat damages only in fruit yield while ‘CY’ was in fruit set, number and yield. ‘NB’ showed fast recovery after heat stress compared to ‘CY’. These results suggest that constant photosynthetic rate via increased transpiration rate as well as high proline content in heat stress condition confer faster recovery from heat damage of heat-tolerant cultivars in seedlings stages.

scholarly journals Heat-tolerant Hot Pepper Exhibits Constant Photosynthesis Via Increased 4 Transpiration Rate, High Proline Content and Fast Recovery in Heat Stress 5 Condition

2021 ◽  
Author(s):  
Sherzod Rajametov ◽  
Eun Young Yang ◽  
Myeong Cheoul Cho ◽  
Soo Young Chae ◽  
Hyo Bong Jeong ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Heat Stress ◽  
Photosynthetic Rate ◽  
Heat Tolerance ◽  
Transpiration Rate ◽  
Proline Content ◽  
Hot Pepper ◽  
Fast Recovery ◽  
Heat Damage ◽  
Heat Tolerant

Understanding the mechanism for heat tolerance is important for the hot pepper breeding program to develop heat-tolerant cultivars in changing climate. This study was conducted to investigate physiological and biochemical parameters related to heat tolerance and to determine leaf heat damage levels critical for selecting heat-tolerant genotypes. Seedlings of two commercial cultivars, heat-tolerant ‘NW Bigarim’ (NB) and susceptible ‘Chyung Yang’ (CY), were grown in 42 °C for ten days. Photosynthesis, electrolyte conductivity, proline content were measured among seedlings during heat treatment. Photosynthetic rate was significantly reduced in ‘CY’ but not in ‘NB’ seedlings in 42 °C. Stomatal conductivity and transpiration rate was significantly higher in ‘NB’ than ‘CY’. Proline content was also significantly higher in ‘NB’. After heat treatment, leaf heat damages were determined as 0, 25, 50 and 75% and plants with different leaf heat damages were moved to a glasshouse (30–32/22–24 °C in day/night). The growth and developmental parameters were investigated until 70 days. ‘NB’ was significantly affected by leaf heat damages only in fruit yield while ‘CY’ was in fruit set, number and yield. ‘NB’ showed fast recovery after heat stress compared to ‘CY’. These results suggest that constant photosynthetic rate via increased transpiration rate as well as high proline content in heat stress condition confer faster recovery from heat damage of heat-tolerant cultivars in seedlings stages.

scholarly journals Effect of Heat Treatment on Physiological and Recovery Growth Status of Two Tomato Cultivars With Different Heat Susceptibility

2021 ◽  
Author(s):  
Sherzod Nigmatullayevich Rajametov ◽  
Eun Young Yang ◽  
Hyo Bong Jeong ◽  
Myeong Cheoul Cho ◽  
Soo-Young Chae ◽  
...  
Keyword(s):  
Heat Stress ◽  
High Temperature ◽  
Stress Tolerance ◽  
Heat Tolerance ◽  
Fruit Set ◽  
Fruit Size ◽  
Seedling Stage ◽  
Screening Methods ◽  
Tomato Cultivars ◽  
Heat Tolerant

High temperature seriously effects on plant vegetative and reproductive development and reduces productivity of plants, while to increase crop yield is the main target in most crop heat stress tolerance improvement breeding programs, not just survival, under high temperature. Our aim was to compare temperature stress tolerance in two commercial tomato cultivars “Dafnis” (big fruit size) and “Minichal” (cherry fruit size) to develop early screening methods and find out survival rate and physiological responses of tomato cultivars on high temperature (40°C and within 70% RH, day/night) in 4-5 true leaf seedling stage- (4LS) and identifies the linkage of heat tolerance with fruit set and leaf heat damage rates (LHD) in seedling stage with subsequent vegetative traits at recovery. Results showed that heat stress significantly affected on physiological-chemical and vegetative parameters of seedlings regardless of tomato cultivars. Survival and the threshold level of high temperature tolerance in the seedlings of cv. “Dafnis” and “Minichal” were identified on days 7 and 9, respectively. Our findings revealed that photosynthesis (PN, Gs, Ci, Tr) parameters were increased and CHL content persisted steady value in cv. “Minichal” during heat stress period, however EC and RPL rates were lower than cv. “Dafnis”. Heat stress reduced the SFW in both cultivars in seedling stage, but PH and RFW were significantly decreased in the heat tolerant cv. “Minichal”, whereas this parameters were not significantly ranged in the heat susceptible cv. “Dafnis”. Additionally, there no found linkage between vegetative parameters with decreasing of PN and CHL rates during HT of seedlings. In plants of cv. “Minichal” with LHD-25, 50 and 75% were no found significant differences in PH, whereas in cv. “Dafnis” significant differences were determined in plants with LHD-75%, and the significant differences in rates of SFW and RFW were observed in plants of cv. “Dafnis” having LHD-75% for 28 days of recovery at NT condition. Taken together, we concluded that heat stress affected on physiological parameters regardless of tolerance level, and to identify heat tolerant genotype in tomato breeding program, screening and selection genotypes have to be evaluated at the vegetative and reproductive stages with consideration fruit size types. Since we could not find linkage between heat tolerances in seedling stage with fruit set at the reproductive stage and fruit set cannot be used as a general predictor of heat tolerance.

scholarly journals Assessment of Heat-tolerance Potential in QTL Introgressed Lines of Hybrid Rice Restorer, KMR-3R through PS-II Efficiency

2021 ◽  
pp. 258-266
Author(s):  
V. Jaldhani ◽  
D. Sanjeeva Rao ◽  
P. Beulah ◽  
B. Srikanth ◽  
P. R. Rao ◽  
...  
Keyword(s):  
High Temperature ◽  
Quantum Yield ◽  
Temperature Stress ◽  
Heat Tolerance ◽  
Photosynthetic Apparatus ◽  
High Temperature Stress ◽  
Maximum Efficiency ◽  
Photochemical Quenching ◽  
Psii Photochemistry ◽  
Heat Tolerant

Aims: To assess heat-induced PSII damage and efficiency in eight promising backcross introgression lines (BC2F6) of KMR-3R/N22 possessing qHTSF1.1 and qHTSF4.1. Study Design:  Randomized Complete Block Design (RCBD) with three replications. Place and Duration of Study: ICAR-Indian Institute of Rice Research, Hyderabad India during wet/rainy (Kharif) season 2018. Methodology: Eight ILs (BC2F6) and parents were evaluated for heat tolerance. The high- temperature stress was imposed by enclosing the crop with a poly cover tent (Polyhouse) just before the anthesis stage. The fluorescence parameters viz., maximum efficiency of PSII photochemistry (Fv/Fm), Electron transport rate (ETR), effective PSII quantum yield (ΦPSII), coefficient of photochemical quenching (qP) and coefficient of non-photochemical quenching (qN) were measured under ambient and high-temperature stress. Results: The heat-tolerance potential of ILs was assessed in terms of PSII activity. The results indicated that significant differences were observed between treatments (T), genotypes (G) and the interaction between T × G.  The physiological basis of introgressed QTLs controls the spikelet fertility by maintaining the productive and adaptive strategies in heat-tolerant QTL introgressed lines with stable photosynthetic apparatus (PSII) under high-temperature stress. Conclusion: The Fv/Fm ratio denotes the maximum quantum yield of PSII. The heat-tolerant QTL introgressed lines exhibited stable photosynthetic apparatus (PSII) and noted better performance under high-temperature stress. They may be used as donors for fluorescence traits in breeding rice for high-temperature tolerance.

scholarly journals Developmental changes in oxygen consumption regulation in larvae of the South African clawed frog Xenopus laevis

1995 ◽  
Vol 198 (12) ◽  
pp. 2465-2475 ◽  
Author(s):  
D Hastings ◽  
W Burggren
Keyword(s):  
Oxygen Consumption ◽  
Lactic Acid ◽  
Xenopus Laevis ◽  
South African ◽  
Acute Hypoxia ◽  
Lactate Concentration ◽  
Aerobic Metabolism ◽  
Whole Body ◽  
Lactate Levels ◽  
Clawed Frog

Well-developed larval Xenopus laevis (NF stages 58­66) are oxygen regulators, at least during mild hypoxia. When and how they change from oxygen conformers (the presumed condition of the fertilized egg) to oxygen regulators is unknown. Also unknown is how anaerobic metabolic capabilities change during development, especially in response to acute hypoxia, and to what extent, if any, anaerobiosis is used to supplement aerobic metabolism. Consequently, we have investigated resting rates of oxygen consumption (M.O2) and concentrations of whole-body lactate (lactic acid) during development in normoxia and in response to acute hypoxia in Xenopus laevis. M.O2 increased in an episodic, non-linear fashion during development. Resting, normoxic M.O2 increased about tenfold (to approximately 0.20 µmol g-1 h-1) between NF stages 1­39 and 40­44, and then another tenfold between NF stages 45­48 and 49­51 (to approximately 2.0 µmol g-1 h-1), remaining at about 2 µmol g-1 h-1 for the remainder of larval development. M.O2 reached its highest level in newly metamorphosed frogs (nearly 4 µmol g-1 h-1), before decreasing to about 1.0 µmol g-1 h-1 in large adults. X. laevis embryos and larvae up to NF stage 54­57 were oxygen conformers when exposed to variable levels of acute hypoxia. The only exception was NF stage 45­48 (external gills present yet body mass still very small), which showed some capability of oxygen regulation. All larvae older than stage 54­57 and adults were oxygen regulators and had the lowest values of Pcrit (the oxygen partial pressure at which M.O2 begins to decline). Whole-body lactate concentration in normoxia was about 1 µmol g-1 for all larval groups, rising to about 12 µmol g-1 in adults. Concentrations of lactic acid in NF stages 1­51 were unaffected by even severe ambient hypoxia. However, whole-body lactate levels in NF stages 52­66 increased in response to severe hypoxia, indicating that some anaerobic metabolism was being used to supplement diminishing aerobic metabolism. The largest increases in concentration of lactate occurred in late larvae and adults.

scholarly journals Cell Membrane Stability as a Measure of Heat Tolerance in Hexaploid and Tetraploid Wheat

2020 ◽  
pp. 16-22
Author(s):  
Syed Bilal Hussain ◽  
Ali Bakhsh ◽  
Muhammad Zubair
Keyword(s):  
High Temperature ◽  
Cell Membrane ◽  
Temperature Stress ◽  
Heat Tolerance ◽  
Tetraploid Wheat ◽  
High Temperature Stress ◽  
Cell Membrane Stability ◽  
Leaf Stage ◽  
Heat Tolerant ◽  
Morphological Differences

A comparison was made of the physiological and morphological differences between Inqlab-91 (hexaploid) and Langdon (tetralpoid) wheat genotypes in response to high temperature stress applied at third leaf stage of growth. Electrolytes leakage technique was used to detect differences in the heat sensitivities of leaves of Inqlab-91 and Langdon. This method showed that at both 35 or 40°C Inqlab-91 was more heat tolerant than Langdon.

Agronomic, physiological and molecular characterisation of rice mutants revealed the key role of reactive oxygen species and catalase in high-temperature stress tolerance

2020 ◽  
Vol 47 (5) ◽  
pp. 440 ◽  
Author(s):  
Syed Adeel Zafar ◽  
Amjad Hameed ◽  
Muhammad Ashraf ◽  
Abdus Salam Khan ◽  
Zia-ul- Qamar ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Heat Stress ◽  
High Temperature ◽  
Grain Yield ◽  
Temperature Stress ◽  
Heat Tolerance ◽  
High Temperature Stress ◽  
Oxygen Species ◽  
Selection Indices ◽  
Heat Tolerant

Climatic variations have increased the occurrence of heat stress during critical growth stages, which negatively affects grain yield in rice. Plants adapt to harsh environments, and particularly high-temperature stress, by regulating their physiological and biochemical processes, which are key tolerance mechanisms. The identification of heat-tolerant rice genotypes and reliable selection indices are crucial for rice improvement programs. Here, we evaluated the response of a rice mutant population for high-temperature stress at the seedling and reproductive stages based on agronomic, physiological and molecular indices. Estimates of variance components revealed significant differences (P < 0.001) among genotypes, treatments and their interactions for almost all traits. The principal component analysis showed significant diversity among genotypes and traits under high-temperature stress. The mutant HTT-121 was identified as the most heat-tolerant mutant with higher grain yield, panicle fertility, cell membrane thermo-stability (CMTS) and antioxidant enzyme levels under heat stress. Various seedling-based morpho-physiological traits (leaf fresh weight, relative water contents, malondialdehyde, CMTS) and biochemical traits (superoxide dismutase, catalase and hydrogen peroxide) explained variations in grain yield that could be used as selection indices for heat tolerance in rice during early growth. Notably, heat-sensitive mutants accumulated reactive oxygen species, reduced catalase activity and upregulated OsSRFP1 expression under heat stress, suggesting their key roles in regulating heat tolerance in rice. The heat-tolerant mutants identified in this study could be used in breeding programs and to develop mapping populations to unravel the underlying genetic architecture for heat-stress adaptability.

Regulation mode of evaporative cooling underlying a strategy of the heat-tolerant FOK rat for enduring ambient heat

2003 ◽  
Vol 285 (6) ◽  
pp. R1439-R1445 ◽  
Author(s):  
Fujiya Furuyama ◽  
Masataka Murakami ◽  
Etsuro Tanaka ◽  
Hideki Hida ◽  
Daisuke Miyazawa ◽  
...  
Keyword(s):  
Heat Tolerance ◽  
Strain Difference ◽  
Strain Differences ◽  
Ambient Temperatures ◽  
Saliva Secretion ◽  
Wide Range ◽  
Heat Tolerant ◽  
Hot Environments ◽  
Regulation Mode

Compared with other rat strains, the inbred FOK rat is extremely heat tolerant. This increased heat tolerance is due largely to the animal's enhanced saliva spreading abilities. The aims of the present study were to 1) quantify the heat tolerance capacity of FOK rats and 2) determine the regulatory mode of the enhanced salivary cooling in these animals. Various strains of rats were acutely exposed to heat. In the heat-intolerant strains, saliva spreading was insufficient and the core temperature (Tc) rose rapidly. In contrast, FOK rats maintained an elevated Tc plateau (39.5 ± 0.7°C) for 5-6 h over a wide range of ambient temperatures (Ta) (37.5-42.5°C). In hot environments the FOK rats secreted copious amounts of saliva and spread it over more than the entire ventral body surface. FOK rats had a low Tc threshold for salivation, and the salivation rate increased linearly in proportion to the Tc deviation from the threshold. No strain difference or temperature effect was observed in the saliva secretion rate from in vitro submandibular glands perfused by sufficient doses of ACh. These results suggest that 1) the ability of FOK rats to maintain a moderate steady-state hyperthermia (39.5 ± 0.7°C) over a wide Ta range is enabled by a lowered threshold Tc for salivation and functional negative-feedback control of saliva secretion and 2) strain differences in ability to endure heat stress are mainly attributable to changes in the thermoregulatory control system rather than altered secretory abilities of the salivary glands.

scholarly journals Effect of Heat Stress on Growth and Physiological Traits of Alfalfa (Medicago sativa L.) and a Comprehensive Evaluation for Heat Tolerance

Agronomy ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 597 ◽  
Author(s):  
Misganaw Wassie ◽  
Weihong Zhang ◽  
Qiang Zhang ◽  
Kang Ji ◽  
Liang Chen
Keyword(s):  
Heat Stress ◽  
Medicago Sativa ◽  
Membership Function ◽  
Heat Tolerance ◽  
Comprehensive Evaluation ◽  
Soluble Sugar ◽  
Fluorescence Analysis ◽  
Relative Water ◽  
Medicago Sativa L ◽  
Heat Tolerant

Alfalfa (Medicago sativa L.) is a valuable forage legume, but its production is largely affected by high temperature. In this study, we investigated the effect of heat stress on 15 alfalfa cultivars to identify heat-tolerant and -sensitive cultivars. Seedlings were exposed to 38/35 °C day/night temperature for 7 days and various parameters were measured. Heat stress significantly reduced the biomass, relative water content (RWC), chlorophyll content, and increased the electrolyte leakage (EL) and malondialdehyde (MDA) content of heat-sensitive alfalfa cultivars. However, heat-tolerant cultivars showed higher soluble sugar (SS) and soluble protein (SP) content. The heat tolerance of each cultivar was comprehensively evaluated based on membership function value. Cultivars with higher mean membership function value of 0.86 (Bara310SC) and 0.80 (Magna995) were heat tolerant, and Gibraltar and WL712 with lower membership function value (0.24) were heat sensitive. The heat tolerance of the above four cultivars were further evaluated by chlorophyll a fluorescence analysis. Heat stress significantly affected the photosynthetic activity of heat-sensitive cultivars. The overall results indicate that Bara310SC and WL712 are heat-tolerant and heat-sensitive cultivars, respectively. This study provides basic information for understanding the effect of heat stress on growth and productivity of alfalfa.

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