scholarly journals Thirty years of coral heat-stress experiments: a review of methods

Coral Reefs ◽  
2020 ◽  
Vol 39 (4) ◽  
pp. 885-902 ◽  
Author(s):  
Rowan H. McLachlan ◽  
James T. Price ◽  
Sarah L. Solomon ◽  
Andréa G. Grottoli
Keyword(s):  
Heat Stress ◽  
Experimental Design ◽  
Coral Bleaching ◽  
Best Practice ◽  
Global Climate ◽  
Coral Host ◽  
Flow Conditions ◽  
Experimental Conditions ◽  
Large Variability ◽  
Acclimation Period

AbstractFor over three decades, scientists have conducted heat-stress experiments to predict how coral will respond to ocean warming due to global climate change. However, there are often conflicting results in the literature that are difficult to resolve, which we hypothesize are a result of unintended biases, variation in experimental design, and underreporting of critical methodological information. Here, we reviewed 255 coral heat-stress experiments to (1) document where and when they were conducted and on which species, (2) assess variability in experimental design, and (3) quantify the diversity of response variables measured. First, we found that two-thirds of studies were conducted in only three countries, three coral species were more heavily studied than others, and only 4% of studies focused on earlier life stages. Second, slightly more than half of all heat-stress exposures were less than 8 d in duration, only 17% of experiments fed corals, and experimental conditions varied widely, including the level and rate of temperature increase, light intensity, number of genets used, and the length of acclimation period. In addition, 95%, 55%, and > 35% of studies did not report tank flow conditions, light–dark cycle used, or the date of the experiment, respectively. Finally, we found that 21% of experiments did not measure any bleaching phenotype traits, 77% did not identify the Symbiodiniaceae endosymbiont, and the contribution of the coral host in the physiological response to heat-stress was often not investigated. This review highlights geographic, taxonomic, and heat-stress duration biases in our understanding of coral bleaching, and large variability in the reporting and design of heat-stress experiments that could account for some of the discrepancies in the literature. Development of some best practice recommendations for coral bleaching experiments could improve cross-studies comparisons and increase the efficiency of coral bleaching research at a time when it is needed most.

scholarly journals An algal symbiont (Breviolum psygmophilum) responds more strongly to chronic high temperatures than its facultatively symbiotic coral host (Astrangia poculata)

2021 ◽  
Author(s):  
Andrea N. Chan ◽  
Luis A. González-Guerrero ◽  
Roberto Iglesias-Prieto ◽  
Elizabeth M. Burmester ◽  
Randi D. Rotjan ◽  
...  
Keyword(s):  
Heat Stress ◽  
Thermal Stress ◽  
Stress Response ◽  
Coral Bleaching ◽  
Scleractinian Corals ◽  
Coral Host ◽  
Algal Symbionts ◽  
Algal Symbiont ◽  
Astrangia Poculata ◽  
And Control

AbstractScleractinian corals form the foundation of coral reefs by secreting skeletons of calcium carbonate. Their intracellular algal symbionts (Symbiodiniaceae) translocate a large proportion of photosynthate to the coral host, which is required to maintain high rates of calcification. Global warming is causing dissociation of coral host and algal symbiont, visibly presented as coral bleaching. Despite decades of study, the precise mechanisms of coral bleaching remain unknown. Separating the thermal stress response of the coral from the algal symbiont is key to understanding bleaching in tropical corals. The facultatively symbiotic northern star coral, Astrangia poculata, naturally occurs as both symbiotic and aposymbiotic (lacking algal symbionts) polyps – sometimes on the same coral colony. Thus, it is possible to separate the heat stress response of the coral host alone from the coral in symbiosis with its symbiont Breviolum psygmophilum. Using replicate symbiotic and aposymbiotic ramets of A. poculata, we conducted a chronic heat stress experiment to increase our understanding of the cellular mechanisms resulting in coral bleaching. Sustained high temperature stress resulted in photosynthetic dysfunction in B. psygmophilum, including a decline in maximum photosynthesis rate, maximum photochemical efficiency, and the absorbance peak of chlorophyll a. Interestingly, the metabolic rates of symbiotic and aposymbiotic corals were differentially impacted. RNAseq analysis revealed more differentially expressed genes between heat-stressed and control aposymbiotic colonies than heat-stressed and control symbiotic colonies. Notably, aposymbiotic colonies increased the expression of inflammation-associated genes such as nitric oxide synthases. Unexpectedly, the largest transcriptional response was observed between heat-stressed and control B. psygmophilum, including genes involved in photosynthesis, response to oxidative stress, and meiosis. Thus, it appears that the algal symbiont suppresses the immune response of the host, potentially increasing the vulnerability of the host to pathogens. The A. poculata-B. psygmophilum symbiosis provides a tractable model system for investigating thermal stress and immune challenge in scleractinian corals.

scholarly journals The role of grapevine leaf morphoanatomical traits in determining capacity for coping with abiotic stresses: a review

2021 ◽  
Vol 36 (1) ◽  
pp. 75-88
Author(s):  
Phoebe MacMillan ◽  
Generosa Teixeira ◽  
Carlos M. Lopes ◽  
Ana Monteiro
Keyword(s):  
Heat Stress ◽  
Abiotic Stresses ◽  
Leaf Blade ◽  
Global Climate ◽  
Wine Production ◽  
Large Variability ◽  
Pavement Cells ◽  
Adaptation Capacity ◽  
Near Future

Worldwide, there are thousands of Vitis vinifera grape cultivars used for wine production, creating a large morphological, anatomical, physiological and molecular diversity that needs to be further characterised and explored, with a focus on their capacity to withstand biotic and abiotic stresses. This knowledge can then be used to select better adapted genotypes in order to help face the challenges of the expected climate changes in the near future. It will also assist grape growers in choosing the most suitable cultivar(s) for each terroir; with adaptation to drought and heat stresses being a fundamental characteristic. The leaf blade of grapevines is the most exposed organ to abiotic stresses, therefore its study regarding the tolerance to water and heat stress is becoming particularly important, mainly in Mediterranean viticulture. This review focuses on grapevine leaf morphoanatomy - leaf blade form, leaf epidermis characteristics (cuticle, indumentum, pavement cells and stomata) and anatomy of mesophyll - and their adaptation to abiotic stresses. V. vinifera xylem architecture and its adaptation capacity when the grapevine is subjected to water stress is also highlighted since grapevines have been observed to exhibit a large variability in responses to water availability. The hydraulic properties of the petiole, shoot and trunk are also reviewed. Summarising, this paper reviews recent advances related to the adaptation of grapevine leaf morphoanatomical features and hydraulic architecture to abiotic stresses, mainly water and heat stress, induced primarily by an ever-changing global climate.

scholarly journals PSVII-6 Effects of heat stress on proteolysis in dairy cattle skeletal muscle

2020 ◽  
Vol 98 (Supplement_3) ◽  
pp. 168-168
Author(s):  
Melissa S Roths ◽  
Megan A Abeyta ◽  
Tori Rudolph ◽  
Brittany Wilson ◽  
Matthew B Hudson ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Heat Stress ◽  
Dairy Cattle ◽  
Electric Heating ◽  
Economic Loss ◽  
Urea Nitrogen ◽  
Plasma Urea ◽  
E3 Ligases ◽  
Acclimation Period ◽  
Milk Urea

Abstract Heat stress (HS) occurs when internal body temperatures are elevated above a thermoneutral zone in response to extreme environmental temperatures. In the U.S. dairy industry, HS results in economic loss due to decreased feed intake, milk quality, and milk yield. Previous work has demonstrated increased plasma urea nitrogen in heat stressed dairy cattle which is thought to originate from increased skeletal muscle proteolysis, however this has not been empirically established. The objective of this investigation was to determine the extent to which HS promotes proteolysis in skeletal muscle of dairy cattle. We hypothesized HS would increase activation of the calpain and proteasome systems in skeletal muscle. To test this hypothesis, following a 3-d acclimation period in individual box stalls, all lactating dairy cows were held under thermoneutral (TN) conditions for 4-d for collection of baseline measures and then exposed to TN or HS conditions for 7-d followed by a biopsy of semitendinosus (n=8/group). To induce HS, cattle were fitted with electric heating blankets, which they wore for the duration of the heating period. This approach increased rectal temperature 1.1°C (P< 0.05), respiratory rate by 33 bpm (P< 0.05), plasma urea nitrogen by 19% (P=0.08) and milk urea nitrogen by 26% (P< 0.05), and decreased dry matter intake by 32% (P< 0.05) and milk production by 26% (P< 0.05) confirming HS. Contrary to our expectations, we discovered that calpain I and II abundance and activation, and calpain activity were similar between groups. Likewise, protein expression of E3 ligases, MafBx and Murf1, were similar between groups as was total ubiquitinated proteins and proteasome activity. Collectively, and counter to our hypothesis, these results suggest skeletal muscle proteolysis is not increased following 7-d of HS. These data question the presumed dogma that increased blood urea nitrogen is due to elevated proteolysis in skeletal muscle.

Wetting and the physiological responses of grain-fed cattle in a heated environment

2004 ◽  
Vol 55 (3) ◽  
pp. 253 ◽  
Author(s):  
John B. Gaughan ◽  
M. Shane Davis ◽  
Terry L. Mader
Keyword(s):  
Heat Stress ◽  
Experimental Design ◽  
Rectal Temperature ◽  
Environmental Conditions ◽  
Dry Matter ◽  
Physiological Responses ◽  
Dry Matter Intake ◽  
Metabolic Responses ◽  
Hot Days ◽  
Carry Over

A controlled crossover experimental design was used to determine the effect of altered water sprinkling duration on heifers subjected to heat stress conditions. Heifers were subjected to 3 days of thermoneutral conditions followed by 3 days of hot conditions accompanied by water sprinkling between 1300 and 1500 h (HOT1–3). Then on the following 2 days (HOT4–5), environmental conditions remained similar, but 3 heifers were sprinkled between 1200 and 1600 h (WET) and 3 were not sprinkled (NONWET). This was followed by a 1-day period (HOT6) in which environmental conditions and sprinkling regimen were similar to HOT1–3. Rectal temperature (RT) was collected hourly, and respiration rate (RR) was monitored every 2 h on HOT Days 2, 4, 5, and 6. Dry matter intake and rate of eating were also determined. Sprinkling reduced RR and RT (P < 0.01) of all heifers during HOT1–3. During HOT4–5, WET heifers had lower (P < 0.05) RT than NONWET from 1300 to 700 h and lower RR from 1400 to 2000 h. Dry matter intake of NONWET heifers was reduced by 30.6% (P < 0.05) during HOT4–5 and by 51.2% on HOT6. On HOT4–5 the dry matter intakes of WET heifers were similar to intakes under thermoneutral conditions. During HOT6, RT was again reduced following sprinkling in all heifers. Comparison of RT and RR of NONWET and WET heifers on HOT1–3 v. HOT6 revealed that under similar environmental conditions, NONWET heifers had increased RT, partially due to carry-over from HOT4–5. However, NONWET heifers had 40% lower feed intake but tended to have lower RR on HOT6 v. HOT1–3. Only RR of WET heifers was greater on HOT6, possibly a result of switching from a 4-h back to a 2-h sprinkling period, while maintaining a 62% greater intake (5.80 v. 3.58 kg/day) than NONWET heifers during this time. Results suggest that inconsistent cooling regimens may increase the susceptibility of cattle to heat stress and elicit different physiological and metabolic responses.

Increasing importance of heat stress for cattle farming under future global climate scenarios

2021 ◽  
pp. 149661
Author(s):  
Mario A. Carvajal ◽  
Alberto J. Alaniz ◽  
Constanza Gutierrez-Gomez ◽  
Pablo M. Vergara ◽  
Veerasamy Sejian ◽  
...  
Keyword(s):  
Heat Stress ◽  
Global Climate ◽  
Climate Scenarios ◽  
Cattle Farming

scholarly journals Enzyme activity in the micropylar region of Melanoxylon brauna Schott seeds during germination under heat stress conditions

2020 ◽  
Vol 42 ◽  
Author(s):  
Marcone Moreira Santos ◽  
Eduardo Euclydes de Lima e Borges ◽  
Glauciana da Mata Ataíde ◽  
Raquel Maria de Oliveira Pires ◽  
Debora Kelli Rocha
Keyword(s):  
Enzyme Activity ◽  
Heat Stress ◽  
Seed Germination ◽  
Pectin Methylesterase ◽  
Stress Conditions ◽  
Southeastern Brazil ◽  
Experimental Conditions ◽  
Mannanase Activity ◽  
Ecological Importance ◽  
The Many

Abstract: Recent studies indicate that global temperatures will rise substantially in the 21st century, leading to the extinction of several plant species, as plant metabolism and germination are greatly affected by temperature. Melanoxylon brauna, a tree species native to the Atlantic Forest that occurs from northeastern to southeastern Brazil, is one of the many species threatened by global warming. Despite the economic and ecological importance of M. brauna, studies investigating the influence of heat stress on seed germination and biochemical responses are still incipient. This study aimed to evaluate enzyme activity in the micropylar region of M. brauna seeds during germination under heat stress conditions. Endo-β-mannanase, α-galactosidase, polygalacturonase, pectin methylesterase, pectin lyase, total cellulase, 1,3-β-glucosidase, and 1,4-β-glucosidase activities were determined in micropyles of seeds imbibed for 24, 48 and 72 h at 25, 35 and 45 °C. Seed germination was highest at 25 °C. Endo-β-mannanase activity was not detected under any of the experimental conditions, but imbibition temperature had a significant effect on the activity of all other enzymes.

Effect of GI and Glogster on Improving the Intercultural Communication Skills in Higher Education

2020 ◽  
pp. 576-604
Author(s):  
Ghada M. Awada ◽  
Hassan B. Diab ◽  
Kawthar H. Faour
Keyword(s):  
Higher Education ◽  
International Students ◽  
Experimental Design ◽  
Intercultural Communication ◽  
Communication Skills ◽  
Intercultural Sensitivity ◽  
Control Group ◽  
Learning Method ◽  
Experimental Conditions ◽  
Experimental Group

The study reports the effect of group investigation (GI) cooperative learning method and the Glogster online poster on improving the intercultural communication skills of international students (n=54) of eight different countries. The study is premised on the proposition that the integration of GI and Glogster in classrooms consisting of Lebanese and non-Lebanese students could be effective in improving the intercultural communication skills of international students and enhancing their perceptions of intercultural communication. The study employed the mixed methods pretest-posttest control group experimental design whereby six Interactions Among Civilizations intact classes were randomly assigned to control and experimental conditions. Employing the intercultural sensitivity scale yielded findings indicating the significance of the GI and Glogster in developing the cultural adaptability and intercultural sensitivity of the experimental group participants (n=25) whereas the control group participants (n=28) did not show similar improvement.

Experiments in social science

2018 ◽  
Author(s):  
John A. Hughes
Keyword(s):  
Social Psychology ◽  
Experimental Design ◽  
Social Science ◽  
Social Research ◽  
Experimental Studies ◽  
Natural Sciences ◽  
Hawthorne Effect ◽  
Experimental Conditions ◽  
Control Factors ◽  
The Social

Within social science the experiment has an ambiguous place. With the possible exception of social psychology, there are few examples of strictly experimental studies. The classic study still often cited is the Hawthorne experiments, which began in 1927, and is used mainly to illustrate what became known as the ‘Hawthorne Effect’, that is, the unintended influence of the research itself on the results of the study. Yet, experimental design is often taken within social research as the embodiment of the scientific method which, if the social sciences are to reach the maturity of the natural sciences, social research should seek to emulate. Meeting this challenge meant trying to devise ways of applying the logic of the experiment to ‘non-experimental’ situations where it was not possible directly to manipulate the experimental conditions. Criticisms have come from two main sources: first, from researchers who claim that the techniques used to control factors within non-experimental situations are unrealizable with current statistical methods and, second, those who reject the very idea of hypothesis-testing as an ambition for social research.

scholarly journals Governing resilient cities for planetary flourishing in the Asia-Pacific

Urban Studies ◽  
2020 ◽  
Vol 57 (7) ◽  
pp. 1359-1371 ◽  
Author(s):  
Michelle Ann Miller ◽  
Mike Douglass ◽  
Jonathan Rigg
Keyword(s):  
Best Practice ◽  
Environmental Governance ◽  
Global Climate ◽  
Well Being ◽  
Asia Pacific ◽  
Urban Region ◽  
Urban Resilience ◽  
Water Demands ◽  
The Pacific ◽  
Urban Energy

For the first time in 2019, the Asia-Pacific became a majority urban region. The unprecedented pace and magnitude of urbanisation across Asia and the Pacific has exposed tens of millions of urban residents to heightened risks and vulnerabilities associated with the expanding ecological footprint of urban energy, food and water demands and the increasingly severe effects of global climate change. This special issue directs attention toward the challenges, innovations and examples of best practice in environmental governance for urban resilience in the Asia-Pacific region. Our understanding of urban resilience is tied to the concept of planetary flourishing that links the health and well-being of urban populations with sustainability behaviours that promote regeneration of the biosphere while redistributing environmental risks and benefits in more socially inclusive and equitable ways.

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