scholarly journals Experimental depletion of gut microbiota diversity reduces host thermal tolerance and fitness under heat stress in a vertebrate ectotherm

2021 ◽  
Author(s):  
Samantha S Fontaine ◽  
Patrick M Mineo ◽  
Kevin D Kohl
Keyword(s):  
Climate Change ◽  
Heat Stress ◽  
Microbial Communities ◽  
Gut Microbiome ◽  
Thermal Tolerance ◽  
Thermal Sensitivity ◽  
Environmental Water ◽  
Mitochondrial Enzymes ◽  
Animal Physiology ◽  
Ectothermic Vertebrate

Predicting the responses of ectotherms to climate change is a global conservation priority which requires identifying factors that influence how animals respond physiologically to changing temperature. Host-associated microbial communities impact animal physiology and have been shown to influence host thermal tolerance in invertebrate systems. However, the role of commensal microbiota in thermal tolerance of ectothermic vertebrates is unknown. Here we show that experimentally depleting the diversity of the tadpole gut microbiome through environmental water sterilization reduces the host's acute thermal tolerance to both heat and cold, alters the thermal sensitivity of locomotor performance, and reduces animal survival under acute heat stress. We show that these tadpoles have reduced activities of mitochondrial enzymes and altered metabolic rates compared to tadpoles colonized with a diverse microbiota, which could underlie differences in thermal phenotypes. Our results demonstrate, for the first time, a link between the gut microbiome of an ectothermic vertebrate and the host's thermal tolerance, performance, and fitness, thus highlighting the importance of considering host-associated microbial communities when predicting species' responses to climate change.

scholarly journals Impact of heat stress on the fitness outcomes of symbiotic infection in aphids: a meta-analysis

2021 ◽  
Author(s):  
Kévin Tougeron ◽  
Corentin Iltis
Keyword(s):  
Climate Change ◽  
Heat Stress ◽  
Evolutionary Dynamics ◽  
Heat Waves ◽  
Thermal Sensitivity ◽  
Meta Analysis ◽  
Terrestrial Ecosystems ◽  
Ecological Niches ◽  
Cascading Effects ◽  
Obligate Symbiont

Beneficial microorganisms shape the evolutionary trajectories of their hosts, facilitating or constraining the colonization of new ecological niches. One convincing example entails the responses of insect-microbe associations to rising temperatures. Indeed, the insect resilience to stressful high temperatures depends on the genetic identity of the obligate symbiont and the presence of heat protective facultative symbionts. With accumulating empirical evidence, there is a need of integrative studies to draw general patterns about the thermal sensitivity of insect-microbe associations, from an eco-evolutionary perspective. Focusing on aphid-bacteria mutualisms, this meta-analysis aims to quantify the context-dependent impacts of symbionts on host phenotype in benign or stressful heat conditions, across fitness traits, types of heat stress, and symbiont species. We found that warming lowered the benefits (parasitoid resistance) and costs (development, fecundity) of infection by facultative symbionts, which was overall mostly beneficial to the aphids under short-term heat stress (heat shock) rather than extended warming. Heat tolerant genotypes of the obligate symbiont Buchnera aphidicola and some facultative symbionts (Rickettsia sp., Serratia symbiotica) improved or maintained aphid fitness under heat stress. As phytophagous insects are central to terrestrial ecosystems, symbiont-mediated responses to increasing mean temperatures and frequency of heat waves in the context of climate change are key elements that may have cascading effects on food webs and there is an urgent need to continue accumulating data on other models. We discuss the implications of these conclusions for the general understanding of the cost-benefits balance and eco-evolutionary dynamics of insect-microbe associations faced with climate change.

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 The microbial world in a changing environment

2021 ◽  
Vol 94 (1) ◽  
Author(s):  
Rafael Vicuña ◽  
Bernardo González
Keyword(s):  
Climate Change ◽  
Microbial Communities ◽  
Recent Literature ◽  
Public Awareness ◽  
Complete Evaluation ◽  
Microbial World ◽  
Sustainable Environment ◽  
Entire Planet ◽  
New Strategies

Abstract Background In this article we would like to touch on the key role played by the microbiota in the maintenance of a sustainable environment in the entire planet. For obvious reasons, this article does not intend to review thoroughly this extremely complex topic, but rather to focus on the main threats that this natural scenario is presently facing. Methods Recent literature survey. Results Despite the relevance of microorganisms have in our planet, the effects of climate change on microbial communities have been scarcely and not systematically addressed in literature. Although the role of microorganisms in emissions of greenhouse gases has received some attention, there are several microbial processes that are affected by climate change with consequences that are presently under assessment. Among them, host-pathogen interactions, the microbiome of built environment, or relations among plants and beneficial microbes. Conclusions Further research is required to advance in knowledge of the effect of climate change on microbial communities. One of the main targets should be a complete evaluation of the global microbial functional diversity and the design of new strategies to cope with limitations in methods to grow microorganisms in the laboratory. These efforts should contribute to raise a general public awareness on the major role played by the microbiota on the various Earth ecosystems.

scholarly journals Urban Geometry Optimization to Mitigate Climate Change: Towards Energy-Efficient Buildings

2020 ◽  
Vol 13 (1) ◽  
pp. 27
Author(s):  
Hatem Mahmoud ◽  
Ayman Ragab
Keyword(s):  
Climate Change ◽  
Heat Stress ◽  
Thermal Efficiency ◽  
Energy Demand ◽  
Building Blocks ◽  
Climate Projections ◽  
Climate Change Scenarios ◽  
Urban Geometry ◽  
Outdoor Spaces ◽  
The Impact

The density of building blocks and insufficient greenery in cities tend to contribute dramatically not only to increased heat stress in the built environment but also to higher energy demand for cooling. Urban planners should, therefore, be conscious of their responsibility to reduce energy usage of buildings along with improving outdoor thermal efficiency. This study examines the impact of numerous proposed urban geometry cases on the thermal efficiency of outer spaces as well as the energy consumption of adjacent buildings under various climate change scenarios as representative concentration pathways (RCP) 4.5 and 8.5 climate projections for New Aswan city in 2035. The investigation was performed at one of the most underutilized outdoor spaces on the new campus of Aswan University in New Aswan city. The potential reduction of heat stress was investigated so as to improve the thermal comfort of the investigated outdoor spaces, as well as energy savings based on the proposed strategies. Accordingly, the most appropriate scenario to be adopted to cope with the inevitable climate change was identified. The proposed scenarios were divided into four categories of parameters. In the first category, shelters partially (25–50% and 75%) covering the streets were used. The second category proposed dividing the space parallel or perpendicular to the existing buildings. The third category was a hybrid scenario of the first and second categories. In the fourth category, a green cover of grass was added. A coupling evaluation was applied utilizing ENVI-met v4.2 and Design-Builder v4.5 to measure and improve the thermal efficiency of the outdoor space and reduce the cooling energy. The results demonstrated that it is better to cover outdoor spaces with 50% of the overall area than transform outdoor spaces into canyons.

Influence of occupational heat stress on labour productivity – a case study from Chennai, India

2016 ◽  
Vol 65 (2) ◽  
pp. 245-255 ◽  
Author(s):  
Jeremiah Chinnadurai ◽  
Vidhya Venugopal ◽  
Kumaravel P ◽  
Paramesh R
Keyword(s):  
Climate Change ◽  
Heart Rate ◽  
Heat Stress ◽  
Pearson Correlation ◽  
Labour Productivity ◽  
Productivity Loss ◽  
Threshold Limit Value ◽  
Control Measures ◽  
Economic Losses ◽  
Content Type

Purpose – Raise in temperatures due to climate change is likely to increase the heat stress in occupations that are physically exerting and performed outdoors which might potentially have adverse health and productivity consequences. The purpose of this paper is to estimate the productivities in construction work under the influence of heat stress using the predicted mean vote (PMV) index. Design/methodology/approach – Field studies were conducted during May 2014 which is summer time in Chennai. Continuous heart rate of workers and wet bulb globe temperature measurements are conducted for workers engaged in different jobs in construction. Metabolic rates and the workload of the workers from heart rate were calculated using the ISO method 8996 and the PMV values are calculated using the tool developed by Malchaire based on the method ISO 7730. Direct observations and personal interviews were conducted to substantiate the productivity estimations. Findings – The results showed that workers working outdoors with moderate and heavy workload exceeded the threshold limit value of 28°C and had adverse productivity impacts (18-35 per cent productivity loss), whereas the workers engaged in light indoor work was not affected by heat stress and consequent productivity losses. The productivity estimations using the PMV index is found to be statistically significant for three types of construction works (Pearson correlation coefficient value of −0.78) and also correlated well with the observations and self-reported productivities of the workers. Originality/value – The method used in this paper provides a scientific and reliable estimation of the productivities which may benefit the industry to set realistic project completion goals in hot weather and also implement interventions and policies to protect workers’ health. Developing adaptive strategies and implementing control measures are the need of the hour to protect worker’s health and economic losses in the face of climate change.

Thermal tolerance in Drosophila : repercussions for distribution, community coexistence and responses to climate change

2021 ◽  
Author(s):  
José M. Alruiz ◽  
Ignacio Peralta‐Maraver ◽  
Francisco Bozinovic ◽  
Mauro Santos ◽  
Enrico L. Rezende
Keyword(s):  
Climate Change ◽  
Thermal Tolerance

Bedeutung des Innenraumklimas und Hitzestress im Zuge des Klimawandels/Importance of indoor climate and heat stress in the era of climate change

Gefahrstoffe ◽  
2021 ◽  
Vol 81 (07-08) ◽  
pp. 279-282
Author(s):  
Thomas Ackermann ◽  
Andreas Matzarakis
Keyword(s):  
Climate Change ◽  
Heat Stress ◽  
Indoor Climate ◽  
Gesetzliche Vorgaben

Hitzewellen, die in Folge des Klimawandels häufiger, intensiver und länger auftreten werden, führen zu einer Belastung des Menschen, insbesondere in Städten. Die dort befindlichen Gebäude und Flächen heizen sich durch die Sonneneinstrahlung tagsüber auf, kühlen aber im Vergleich zum weniger verdichteten Umland während der Nachtphase geringfügiger ab. Die sich daraus ergebenden langanhaltend hohen Temperaturen wirken sich besonders belastend auf den menschlichen Körper aus und verursachen negative Folgen, wie den Anstieg der Mortalität. Um mit den künftig intensiveren Hitzewellen besser umgehen zu können und um Gesundheitsrisiken zu vermeiden, sollten für städtische Räume und dort vor allem für Innenräume Anpassungsmaßnahmen entwickelt werden. Darüber hinaus sollten Regelungen getroffen werden, die sowohl im Zusammenhang mit dem Energieverbrauch bzw. Wärmeschutz stehen, als auch gesetzliche Vorgaben bezüglich Grenz- und Schwellenwerten berücksichtigen und dabei nicht nur auf der Lufttemperatur beruhen, sondern thermische Indizes, die auf den Wärmeaustausch des Menschen und die thermischen Auswirkungen besser quantitativ beschreiben können.

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