scholarly journals Interactions between developmental and adult acclimation have distinct consequences for heat-tolerance and heat-stress recovery

2021 ◽  
Author(s):  
Quentin Willot ◽  
Ben Loos ◽  
John S. Terblanche
Keyword(s):  
Heat Stress ◽  
Heat Tolerance ◽  
Thermal Tolerance ◽  
Climatic Conditions ◽  
Distinct Pattern ◽  
Recovery Rates ◽  
Relative Contribution ◽  
Heat Hardening ◽  
Full Factorial Experimental Design ◽  
Post Stress

Developmental and adult thermal acclimation can have distinct, even opposite, effects on adult heat resistance in ectotherms. Yet, their relative contribution to heat-hardiness of ectotherms remains unclear despite the broad ecological implications thereof. Furthermore, the deterministic relationship between heat-knockdown and recovery from heat stress is poorly understood but significant for establishing causal links between climate variability and population dynamics. Here, using D. melanogaster in a full-factorial experimental design, we assess flies heat-tolerance in static stress assays, and document how developmental and adult acclimation interact with a distinct pattern to promote survival to heat-stress in adults. We show that warmer adult acclimation is the initial factor enhancing survival to constant stressful high temperatures in flies, but also that the interaction between adult and developmental acclimation becomes gradually more important to ensure survival as the stress persists. This provides an important framework revealing the dynamic interplay between these two forms of acclimation, that ultimately enhance thermal tolerance as a function of stress duration. Furthermore, by investigating recovery rates post-stress, we also show that the process of heat-hardening and recovery post heat knockdown are likely to be based on set of (at least partially) divergent mechanisms. This could bear ecological significance as a tradeoff may exist between increasing thermal tolerance and maximizing recovery rates post-stress, constraining population responses when exposed to variable and stressful climatic conditions.

Improving sustainable cotton production through enhanced resilience to climate change using mutation breeding.

2021 ◽  
pp. 145-156
Author(s):  
Manzoor Hussain ◽  
Ljupcho Jankuloski ◽  
M. Habib-ur-Rahman ◽  
Massoud Malek ◽  
Md. Kamrul Islam ◽  
...  
Keyword(s):  
Climate Change ◽  
Heat Stress ◽  
Heat Tolerance ◽  
Mutation Breeding ◽  
Climatic Conditions ◽  
Cotton Production ◽  
Climate Conditions ◽  
Growing Seasons ◽  
Major Factors ◽  
High Yields

Abstract Cotton, being a leading commercial fibre crop, is grown on 20.5 million hectares in three major cotton-producing countries: China, India and Pakistan. Wide differences in yield per hectare exist among these countries and these are being aggravated by changing climate conditions, i.e. higher temperatures and significant seasonal and regional fluctuation in rainfall. Pakistan is one of the countries most affected by climate change. The disastrous effects of extreme periods of heat stress in cotton were very prominent in Pakistan during the growing seasons 2013-2014 (40-50% fruit abortion) and 2016-2017 (33% shortfall), which posed an alarming threat to the cotton-based economy of Pakistan. Poor resilience of the most commonly grown cotton varieties against extreme periods of heat stress are considered to be major factors for this drastic downfall in cotton production in Pakistan. Using the approach of induced mutation breeding, the Nuclear Institute for Agriculture and Biology (NIAB), Faisalabad, Pakistan, has demonstrated its capabilities in developing cotton mutants that can tolerate the changed climatic conditions and sustain high yields under contrasting environments. The results of studies on the phenological and physiological traits conferring heat tolerance are presented here for thermo-tolerant cotton mutants (NIAB-878, NIAB-545, NIAB-1048, NIAB-444, NIAB-1089, NIAB-1064, NIAB-1042) relative to FH-142 and FH-Lalazar. NIAB-878 excelled in heat tolerance by maintaining the highest anther dehiscence (82%) and minimum cell injury percentage (39%) along with maximum stomatal conductance (27.7 mmol CO2/m2/s), transpiration rate (6.89 μmol H2O/m2/s), net photosynthetic rate (44.6 mmol CO2/m2/s) and physiological water use efficiency (6.81 mmol CO2/μmol H2O) under the prevailing high temperatures.

scholarly journals Comparison of Static and Dynamic Assays When Quantifying Thermal Plasticity of Drosophilids

Insects ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 537
Author(s):  
Christian Winther Bak ◽  
Simon Bahrndorff ◽  
Natasja Krog Noer ◽  
Lisa Bjerregaard Jørgensen ◽  
Johannes Overgaard ◽  
...  
Keyword(s):  
Critical Temperature ◽  
Constant Temperature ◽  
Heat Tolerance ◽  
Thermal Tolerance ◽  
Physiological Trait ◽  
Thermal Plasticity ◽  
Heat Hardening ◽  
Temperature Interaction ◽  
Dynamic Assay ◽  
Species Specific

Numerous assays are used to quantify thermal tolerance of arthropods including dynamic ramping and static knockdown assays. The dynamic assay measures a critical temperature while the animal is gradually heated, whereas the static assay measures the time to knockdown at a constant temperature. Previous studies indicate that heat tolerance measured by both assays can be reconciled using the time × temperature interaction from “thermal tolerance landscapes” (TTLs) in unhardened animals. To investigate if this relationship remains true within hardened animals, we use a static assay to assess the effect of heat hardening treatments on heat tolerance in 10 Drosophila species. Using this TTL approach and data from the static heat knockdown experiments, we model the expected change in dynamic heat knockdown temperature (CTmax: temperature at which flies enter coma) and compare these predictions to empirical measurements of CTmax. We find that heat tolerance and hardening capacity are highly species specific and that the two assays report similar and consistent responses to heat hardening. Tested assays are therefore likely to measure the same underlying physiological trait and provide directly comparable estimates of heat tolerance. Regardless of this compliance, we discuss why and when static or dynamic assays may be more appropriate to investigate ectotherm heat tolerance.

scholarly journals Gut Microbiota of Drosophila subobscura Contributes to Its Heat Tolerance and Is Sensitive to Transient Thermal Stress

2021 ◽  
Vol 12 ◽  
Author(s):  
Angélica Jaramillo ◽  
Luis E. Castañeda
Keyword(s):  
Heat Stress ◽  
Community Structure ◽  
Thermal Stress ◽  
Gut Microbiota ◽  
Heat Tolerance ◽  
Thermal Tolerance ◽  
Drosophila Subobscura ◽  
Transient Thermal ◽  
The Impact

The gut microbiota can contribute to host physiology leading to an increase of resistance to abiotic stress conditions. For instance, temperature has profound effects on ectotherms, and the role of the gut microbiota on the thermal tolerance of ectotherms is a matter of recent research. However, most of these studies have been focused on single static temperatures instead of evaluating thermal tolerance in a wide range of stressful temperatures. Additionally, there is evidence supporting that the gut microbiota is sensitive to environmental temperature, which induces changes in its composition and diversity. These studies have evaluated the effects of thermal acclimation (>2 weeks) on the gut microbiota, but we know little about the impact of transient thermal stress on the composition and diversity of the gut microbiota. Thus, we investigated the role of the gut microbiota on the heat tolerance of Drosophila subobscura by measuring the heat tolerance of conventional and axenic flies exposed to different heat stressful temperatures (35, 36, 37, and 38°C) and estimating the heat tolerance landscape for both microbiota treatments. Conventional flies exposed to mild heat conditions exhibited higher thermal tolerance than axenic flies, whereas at higher stressful temperatures there were no differences between axenic and conventional flies. We also assessed the impact of transient heat stress on the taxonomical abundance, diversity, and community structure of the gut microbiota, comparing non-stressed flies (exposed to 21°C) and heat-stressed flies (exposed to 34°C) from both sexes. Bacterial diversity indices, bacterial abundances, and community structure changed between non-stressed and heat-stressed flies, and this response was sex-dependent. In general, our findings provide evidence that the gut microbiota influences heat tolerance and that heat stress modifies the gut microbiota at the taxonomical and structural levels. These results demonstrate that the gut microbiota contributes to heat tolerance and is also highly sensitive to transient heat stress, which could have important consequences on host fitness, population risk extinction, and the vulnerability of ectotherms to current and future climatic conditions.

scholarly journals Plastic responses of survival and fertility following heat stress in pupal and adult Drosophila virilis

2021 ◽  
Author(s):  
Benjamin Walsh ◽  
Steven Parratt ◽  
Natasha Mannion ◽  
Rhonda Snook ◽  
Amanda Bretman ◽  
...  
Keyword(s):  
Heat Stress ◽  
High Temperature ◽  
Temperature Stress ◽  
High Temperatures ◽  
Male Fertility ◽  
Thermal Tolerance ◽  
Drosophila Virilis ◽  
Life History Stage ◽  
Heat Hardening ◽  
The Impact

The impact of rising global temperatures on survival and reproduction is putting many species at risk of extinction. In particular, it has recently been shown that thermal effects on reproduction, especially limits to male fertility, can underpin species distributions in insects. However, the physiological factors influencing fertility at high temperatures are poorly understood. Key factors that affect somatic thermal tolerance such as hardening, the ability to phenotypically increase thermal tolerance after a mild heat shock, and the differential impact of temperature on different life stages, are largely unexplored for thermal fertility tolerance. Here, we examine the impact of high temperatures on male fertility in the cosmopolitan fruit fly Drosophila virilis. We first determined whether temperature stress at either the pupal or adult life-history stage impacts fertility. We then tested the capacity for heat-hardening to mitigate heat-induced sterility. We found that thermal stress reduces fertility in different ways in pupae and adults. Pupal heat stress delays sexual maturity, whereas males heated as adults can reproduce initially following heat stress, but lose the ability to produce offspring. We also found evidence that while heat-hardening in D. virilis can improve high temperature survival, there is no significant protective impact of this same hardening treatment on fertility. These results suggest that males may be unable to prevent the costs of high temperature stress on fertility through heat-hardening which limits a species’ ability to quickly and effectively reduce fertility loss in the face of short-term high temperature events.

scholarly journals Oxygen supply limits the heat tolerance of locusts during the first instar only

2020 ◽  
Author(s):  
Jacob P. Youngblood ◽  
John M. VandenBrooks ◽  
Oluwatosin Babarinde ◽  
Megan E. Donnay ◽  
Deanna B. Elliott ◽  
...  
Keyword(s):  
Heat Stress ◽  
Heat Tolerance ◽  
Thermal Tolerance ◽  
Oxygen Supply ◽  
Oxygen Limitation ◽  
Life Stages ◽  
First Instar ◽  
Wide Range ◽  
Survival And Reproduction ◽  
Respiratory Systems

AbstractExtreme heat directly limits an organism’s survival and reproduction, but scientists cannot agree on what causes organisms to lose function or die during heating. According to the theory of oxygen- and capacity-limitation of thermal tolerance, heat stress occurs when a warming organism’s demand for oxygen exceeds its supply, triggering a widespread drop in ATP concentration. This model predicts that an organism’s heat tolerance should decrease under hypoxia, yet most terrestrial organisms tolerate the same amount of warming across a wide range of oxygen concentrations. This point is especially true for adult insects, who deliver oxygen through highly efficient respiratory systems. However, oxygen limitation at high temperatures may be more common during immature life stages, which have less developed respiratory systems. To test this hypothesis, we measured the effects of heat and hypoxia on the survival of locusts (Schistocerca cancellata) throughout development. We demonstrate that the heat tolerance of locusts depends on oxygen supply during the first instar but not during later instars. This finding provides further support for the idea that oxygen limitation of thermal tolerance depends on respiratory performance, especially during immature life stages.

scholarly journals Gut microbiota of Drosophila subobscura contributes to its heat tolerance but is sensitive to transient thermal stress

2021 ◽  
Author(s):  
Angelica Jaramillo ◽  
Luis E. Castaneda
Keyword(s):  
Heat Stress ◽  
Gut Microbiota ◽  
Heat Tolerance ◽  
Extinction Risk ◽  
Climatic Conditions ◽  
Drosophila Subobscura ◽  
Highly Sensitive ◽  
Transient Thermal ◽  
Structural Levels ◽  
The Impact

Global warming impacts animal fitness, leading to increasing extinction risk in ectotherm species. Gut microbiota can contribute to host physiology leading to an increase of resistance to abiotic stress conditions. Temperature has profound effects on ectotherms and gut microbiota can influence cold and heat tolerance of ectotherm species. Additionally, the gut microbiota is sensitive to environmental temperature, which induces changes in its composition and diversity. Here, we investigated the role of the gut microbiota on heat tolerance of Drosophila subobscura comparing the knockdown time between conventional and axenic, and we also assessed the impact of heat stress on the diversity and community structure of the gut microbiota, comparing non-stressed and heat-stressed flies. Our findings provide evidence that gut microbiota influences heat tolerance, and that heat stress modifies the gut microbiota at taxonomical and structural levels. These results demonstrate that gut microbiota contributes to heat tolerance but it is also highly sensitive to transient heat stress, which could have important effects on host fitness, population risk extinction, and vulnerability of ectotherms to current and future climatic conditions.

scholarly journals A positive genetic correlation between hypoxia tolerance and heat tolerance supports a controversial theory of heat stress

2017 ◽  
Vol 13 (11) ◽  
pp. 20170309 ◽  
Author(s):  
Collin Teague ◽  
Jacob P. Youngblood ◽  
Kinley Ragan ◽  
Michael J. Angilletta ◽  
John M. VandenBrooks
Keyword(s):  
Drosophila Melanogaster ◽  
Heat Stress ◽  
Genetic Correlation ◽  
Heat Tolerance ◽  
Quantitative Genetics ◽  
Thermal Tolerance ◽  
Model Organism ◽  
Hypoxia Tolerance ◽  
Hypoxic Stress ◽  
Adaptation To Heat

We used quantitative genetics to test a controversial theory of heat stress, in which animals overheat when the demand for oxygen exceeds the supply. This theory, referred to as oxygen- and capacity-limited thermal tolerance, predicts a positive genetic correlation between hypoxia tolerance and heat tolerance. We demonstrate the first genetic correlation of this kind in a model organism, Drosophila melanogaster . Genotypes more likely to fly under hypoxic stress (12% O 2 ) were also more likely to fly under heat stress (39°C). This finding prompts new questions about mechanisms and limits of adaptation to heat stress.

scholarly journals Thermal Inactivation of Susceptible and Multiantimicrobial-Resistant Salmonella Strains Grown in the Absence or Presence of Glucose

2003 ◽  
Vol 69 (7) ◽  
pp. 4123-4128 ◽  
Author(s):  
R. T. Bacon ◽  
J. R. Ransom ◽  
J. N. Sofos ◽  
P. A. Kendall ◽  
K. E. Belk ◽  
...  
Keyword(s):  
Heat Stress ◽  
Protective Effect ◽  
Thermal Tolerance ◽  
Thermal Inactivation ◽  
Survival Curves ◽  
Acid Adaptation ◽  
Circulating Water ◽  
Glucose Levels ◽  
Study Results ◽  
Peptone Water

ABSTRACT The heat resistance of susceptible and multiantimicrobial-resistant Salmonella strains grown to stationary phase in glucose-free tryptic soy broth supplemented with 0.6% yeast extract (TSBYE−G; nonadapted), in regular (0.25% glucose) TSBYE, or in TSBYE−G with 1.00% added glucose (TSBYE+G; acid adapted) was determined at 55, 57, 59, and 61°C. Cultures were heated in sterile 0.1% buffered peptone water (50 μl) in heat-sealed capillary tubes immersed in a thermostatically controlled circulating-water bath. Decimal reduction times (D values) were calculated from survival curves having r 2 values of >0.90 as a means of comparing thermal tolerance among variables. D 59°C values increased (P < 0.05) from 0.50 to 0.58 to 0.66 min for TSBYE−G, TSBYE, and TSBYE+G cultures, respectively. D 61°C values of antimicrobial-susceptible Salmonella strains increased (P < 0.05) from 0.14 to 0.19 as the glucose concentration increased from 0.00 to 1.00%, respectively, while D 61°C values of multiantimicrobial-resistant Salmonella strains did not differ (P > 0.05) between TSBYE−G and TSBYE+G cultures. When averaged across glucose levels and temperatures, there were no differences (P > 0.05) between the D values of susceptible and multiantimicrobial-resistant inocula. Collectively, D values ranged from 4.23 to 5.39, 1.47 to 1.81, 0.50 to 0.66, and 0.16 to 0.20 min for Salmonella strains inactivated at 55, 57, 59, and 61°C, respectively. zD values were 1.20, 1.48, and 1.49°C for Salmonella strains grown in TSBYE+G, TSBYE, and TSBYE−G, respectively, while the corresponding activation energies of inactivation were 497, 493, and 494 kJ/mol. Study results suggested a cross-protective effect of acid adaptation on thermal inactivation but no association between antimicrobial susceptibility and the ability of salmonellae to survive heat stress.

scholarly journals Genotype-by-environment interaction in Holstein heifer fertility traits using single-step genomic reaction norm models

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Rui Shi ◽  
Luiz Fernando Brito ◽  
Aoxing Liu ◽  
Hanpeng Luo ◽  
Ziwei Chen ◽  
...  
Keyword(s):  
Heat Stress ◽  
Dairy Cattle ◽  
Candidate Genes ◽  
Heat Tolerance ◽  
Reaction Norm ◽  
Single Step ◽  
Conception Rate ◽  
Critical Periods ◽  
Genotype By Environment ◽  
Fertility Traits

Abstract Background The effect of heat stress on livestock production is a worldwide issue. Animal performance is influenced by exposure to harsh environmental conditions potentially causing genotype-by-environment interactions (G × E), especially in highproducing animals. In this context, the main objectives of this study were to (1) detect the time periods in which heifer fertility traits are more sensitive to the exposure to high environmental temperature and/or humidity, (2) investigate G × E due to heat stress in heifer fertility traits, and, (3) identify genomic regions associated with heifer fertility and heat tolerance in Holstein cattle. Results Phenotypic records for three heifer fertility traits (i.e., age at first calving, interval from first to last service, and conception rate at the first service) were collected, from 2005 to 2018, for 56,998 Holstein heifers raised in 15 herds in the Beijing area (China). By integrating environmental data, including hourly air temperature and relative humidity, the critical periods in which the heifers are more sensitive to heat stress were located in more than 30 days before the first service for age at first calving and interval from first to last service, or 10 days before and less than 60 days after the first service for conception rate. Using reaction norm models, significant G × E was detected for all three traits regarding both environmental gradients, proportion of days exceeding heat threshold, and minimum temperature-humidity index. Through single-step genome-wide association studies, PLAG1, AMHR2, SP1, KRT8, KRT18, MLH1, and EOMES were suggested as candidate genes for heifer fertility. The genes HCRTR1, AGRP, PC, and GUCY1B1 are strong candidates for association with heat tolerance. Conclusions The critical periods in which the reproductive performance of heifers is more sensitive to heat stress are trait-dependent. Thus, detailed analysis should be conducted to determine this particular period for other fertility traits. The considerable magnitude of G × E and sire re-ranking indicates the necessity to consider G × E in dairy cattle breeding schemes. This will enable selection of more heat-tolerant animals with high reproductive efficiency under harsh climatic conditions. Lastly, the candidate genes identified to be linked with response to heat stress provide a better understanding of the underlying biological mechanisms of heat tolerance in dairy cattle.

scholarly journals Differential Morpho-Physiological and Transcriptomic Responses to Heat Stress in Two Blueberry Species

2021 ◽  
Vol 22 (5) ◽  
pp. 2481
Author(s):  
Jodi Callwood ◽  
Kalpalatha Melmaiee ◽  
Krishnanand P. Kulkarni ◽  
Amaranatha R. Vennapusa ◽  
Diarra Aicha ◽  
...  
Keyword(s):  
Heat Stress ◽  
Molecular Mechanisms ◽  
Stomatal Closure ◽  
Enrichment Analysis ◽  
Leaf Size ◽  
Vaccinium Corymbosum ◽  
Climatic Conditions ◽  
Differentially Expressed ◽  
Transcriptomic Changes ◽  
Go Terms

Blueberries (Vaccinium spp.) are highly vulnerable to changing climatic conditions, especially increasing temperatures. To gain insight into mechanisms underpinning the response to heat stress, two blueberry species were subjected to heat stress for 6 and 9 h at 45 °C, and leaf samples were used to study the morpho-physiological and transcriptomic changes. As compared with Vaccinium corymbosum, Vaccinium darrowii exhibited thermal stress adaptation features such as small leaf size, parallel leaf orientation, waxy leaf coating, increased stomatal surface area, and stomatal closure. RNAseq analysis yielded ~135 million reads and identified 8305 differentially expressed genes (DEGs) during heat stress against the control samples. In V. corymbosum, 2861 and 4565 genes were differentially expressed at 6 and 9 h of heat stress, whereas in V. darrowii, 2516 and 3072 DEGs were differentially expressed at 6 and 9 h, respectively. Among the pathways, the protein processing in the endoplasmic reticulum (ER) was the highly enriched pathway in both the species: however, certain metabolic, fatty acid, photosynthesis-related, peroxisomal, and circadian rhythm pathways were enriched differently among the species. KEGG enrichment analysis of the DEGs revealed important biosynthesis and metabolic pathways crucial in response to heat stress. The GO terms enriched in both the species under heat stress were similar, but more DEGs were enriched for GO terms in V. darrowii than the V. corymbosum. Together, these results elucidate the differential response of morpho-physiological and molecular mechanisms used by both the blueberry species under heat stress, and help in understanding the complex mechanisms involved in heat stress tolerance.

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