Heat Stress Resistance Research Articles

Bacterial processing of glucose modulates C. elegans lifespan and healthspan

Intestinal microbiota play an essential role in the health of a host organism. Here, we define how commensal Escherichia coli (E. coli) alters its host after long term exposure to glucose using a Caenorhabditis elegans-E. coli system where only the bacteria have direct contact with glucose. Our data reveal that bacterial processing of glucose results in reduced lifespan and healthspan including reduced locomotion, oxidative stress resistance, and heat stress resistance in C. elegans. With chronic exposure to glucose, E. coli exhibits growth defects and increased advanced glycation end products. These negative effects are abrogated when the E. coli is not able to process the additional glucose and by the addition of the anti-glycation compound carnosine. Physiological changes of the host C. elegans are accompanied by dysregulation of detoxifying genes including glyoxalase, glutathione-S-transferase, and superoxide dismutase. Loss of the glutathione-S-transferase, gst-4 shortens C. elegans lifespan and blunts the animal's response to a glucose fed bacterial diet. Taken together, we reveal that added dietary sugar may alter intestinal microbial E. coli to decrease lifespan and healthspan of the host and define a critical role of detoxification genes in maintaining health during a chronic high-sugar diet.

Climate sensitivity of milk production traits and milk fatty acids in genotyped Holstein dairy cows

The aim of this study was the evaluation of climate sensitivity via genomic reaction norm models [i.e., to infer cow milk production and milk fatty acid (FA) responses on temperature-humidity index (THI) alterations]. Test-day milk traits were recorded between 2010 and 2016 from 5,257 first-lactation genotyped Holstein dairy cows. The cows were kept in 16 large-scale cooperator herds, being daughters of 344 genotyped sires. The longitudinal data consisted of 47,789 test-day records for the production traits milk yield (MY), fat yield (FY), and protein yield (PY), and of 20,742 test-day records for 6 FA including C16:0, C18:0, saturated fatty acids (SFA), unsaturated fatty acids (UFA), monounsaturated fatty acids (MUFA), and polyunsaturated fatty acids (PUFA). After quality control of the genotypic data, 41,057 SNP markers remained for genomic analyses. Meteorological data from the weather station in closest herd distance were used for the calculation of maximum hourly daily THI. Genomic reaction norm models were applied to estimate genetic parameters in a single-step approach for production traits and FA in dependency of THI at different lactation stages, and to evaluate the model stability. In a first evaluation strategy (New_sire), all phenotypic records from daughters of genotyped sires born after 2010 were masked, to mimic a validation population. In the second strategy (New_env), only daughter records of the new sires recorded in the most extreme THI classes were masked, aiming at predicting sire genomic estimated breeding values (GEBV) under heat stress conditions. Model stability was the correlation between GEBV of the new sires in the reduced data set with respective GEBV estimated from all phenotypic data. Among all test-day production traits, PY responded as the most sensitive to heat stress. As observed for the remaining production traits, genetic variances were quite stable across THI, but genetic correlations between PY from temperate climates with PY from extreme THI classes dropped to 0.68. Genetic variances in dependency of THI were very similar for C16:0 and SFA, indicating marginal climatic sensitivity. In the early lactation stage, genetic variances for C18:0, MUFA, PUFA, and UFA were significantly larger in the extreme THI classes compared with the estimates under thermoneutral conditions. For C18:0 and MUFA, PUFA, and UFA in the middle THI classes, genetic correlations in same traits from the early and the later lactation stages were lower than 0.50, indicating strong days in milk influence. Interestingly, within lactation stages, genetic correlations for C18:0 and UFA recorded at low and high THI were quite large, indicating similar genetic mechanisms under stress conditions. The model stability was improved when applying the New_env instead of New_sire strategy, especially for FA in the first stage of lactation. Results indicate moderately accurate genomic predictions for milk traits in extreme THI classes when considering phenotypic data from a broad range of remaining THI. Phenotypically, thermal stress conditions contributed to an increase of UFA, suggesting value as a heat stress biomarker. Furthermore, the quite large genetic variances for UFA at high THI suggest the consideration of UFA in selection strategies for improved heat stress resistance.

Unique Wolbachia strain wMelPlus increases heat stress resistance in Drosophila melanogaster.

Maternally inherited endosymbiotic bacterium Wolbachia infects Drosophila melanogaster populations worldwide. Its genetic diversity includes several closely related genotypes, which can be attributed to two main genotype groups: wMel and wMelCS. Here, we studied eight D. melanogaster lines carrying the nuclear background of wild type interbred Bi90 line and cytoplasmic backgrounds with or without Wolbachia of different origin, each of which belongs to wMelCS genotype group. We analyzed the effect these seven Wolbachia strains had on the heat stress resistance and dopamine metabolism in D. melanogaster females. Survival under heat stress (38°C, 3 h 30 min) was increased only in the line infected with bacteria of the wMelPlus strain. At the same time, the activity of alkaline phosphatase (an enzyme regulating the pool of dopamine precursor tyrosine) was increased under normal conditions in females infected with all strains under study and retained the response to heat stress typical for the uninfected line. Thus, we found the unique Wolbachia strain that provides an increase of the host stress resistance, and demonstrated that the mechanism of this resistance is not dopamine-mediated.

The effects of astragalus polysaccharides on the growth, heat stress tolerance and related gene expression of the leech Whitmania pigra

Whitmania pigra is an aquatic annelid with broad pharmacological effects and is widely used for treatment of cardiovascular diseases in Asia. One of the main factors limiting its commercial production is its weak heat stress tolerance. To assess the effects of astragalus polysaccharide (APS) on the growth and heat stress tolerance of W. pigra and the underlying mechanisms, six APS concentration treatments (0‰, 0.01‰, 0.03‰, 0.05‰, 0.07‰ and 0.09‰) were formulated to explore their influence on growth, digestive enzymes and the expression of immune- and growth-related genes at 26°C or 35°C. The results showed that APS significantly enhanced the final weight, weight gain rate, specific growth rate, digestive enzyme and anti-reverse enzyme activity, and the relative expression level of growth hormone, insulin-like growth factor-1 and digestive enzyme-related genes. The 0.07‰ APS group showed significantly greater values than the other groups (p < 0.05). APS up-regulated the relative expression of HSP70 and immune-related genes under heat stress, and the 0.07‰ group showed the greatest modulatory effect. Overall, APS can promote growth, immunity and heat stress resistance in W. pigra, and the recommendation dietary APS level was 0.07‰.

Heat stress resistance drives coordination of emissions of suites of volatiles after severe heat stress and during recovery in five tropical crops

Severe heat stress leads to a major reduction in foliage photosynthetic characteristics and the initial reduction and degree of recovery depend on species heat resistance. However, how the emissions of biogenic volatile organic compounds (BVOC) from different biochemical pathways are coordinated with photosynthetic modifications from the initial stress response through recovery are poorly understood, and the data are especially limited for short-living tropical crop species. We exposed leaves of five tropical crop species (A. cruentus, A. hybridus, S. aethiopicum, T. occidentalis and V. unguiculata) to severe heat treatment of 49 °C and a control treatment of 25 °C for 5 min and studied the modifications in foliage photosynthetic characteristics and constitutive BVOC emissions and elicitation of stress-induced volatiles through a 48 h recovery period upon return to non-stressed conditions. Overall, heat shock application resulted in a major inhibition of net assimilation rate similarly in all species indicating cellular damage and photosynthetic decay. However, species strongly varied in photosynthetic recovery with A. hybridus recovering the most and S. aethiopicum the least. Heat shock stress led to enhancement of emissions characterizing increased leaf oxidative status, in particular to enhanced emissions of lipoxygenase pathway volatiles (LOX). Surprisingly, LOX emissions were not associated with species heat resistance, but were greater in physiologically more active species with greater photosynthetic capacity. Species with greater constitutive isoprenoid emission capacity were generally more heat resistant, but terpenoid emissions were induced to a greater degree in less heat resistant species that likely suffered the most from the applied level of stress. Heat stress affected different groups of terpenoids - isoprene, monoterpenes and sesquiterpenes - to a different degree in different species, resulting in unique species-specific emission blends at different times of recovery. Heat stress had relatively minor effects on benzenoid emissions with moderately enhanced emissions primarily in V. unguiculata that differed from the other species by lower constitutive terpenoid emissions correspondent to its relatively high heat resistance. The results collectively demonstrate that species heat resistance is associated with the quantitative and qualitative characteristics of heat stress-dependent volatile emissions in different tropical crop species. We argue that these species-specific patterns need consideration in simulating volatile emissions under heat stress.

Effect of chronic β-radiation on long-distance electrical signals in wheat and their role in adaptation to heat stress

Plants are unavoidably exposed to ionizing radiation (IR) from natural and anthropogenic sources. Along with the chronic irradiation, plants are influenced by other environmental stress factors, to which they must adapt. We suppose that high background radiation modifies plant response to environmental stressors by influencing the stress signaling which are the crucial players in induction and orchestrating the formation of plant adaptation. Chronic β-radiation (31.3 μGy/h) does not cause pronounced oxidative stress and significant changes in morphometric parameters of wheat seedlings (Triticum aestivum L.). At the same time, chronic IR exposure causes slight activation of transpiration and assimilation, and activates H+-ATPase-dependent transmembrane transport. In irradiated plants, there is an increase in the amplitude, velocity and propagation distance of electrical signals induced by a local stimulus. Accordingly, in irradiated plants, photosynthesis and transpiration responses caused by an electrical signal are significantly enhanced. The opposite effect of the electric signal on heat stress resistance was found: after the signal passing, the resistance of control plants increases, but it decreases for irradiated plants. It is assumed that the inversion of the effect is resulted from the enhanced responses of transpiration due to the electrical signals amplification.

Antiaging Effects of Vicatia thibetica de Boiss Root Extract on Caenorhabditis elegans and Doxorubicin‐Induced Premature Aging in Adult Mice

The roots of Vicatia thibetica de Boiss are a kind of Chinese herb with homology of medicine and food. This is the first report showing the property of the extract of Vicatia thibetica de Boiss roots (HLB01) to extend the lifespan as well as promote the healthy parameters in Caenorhabditis elegans (C. elegans). For doxorubicin- (Doxo-) induced premature aging in adult mice, HLB01 counteracted the senescence-associated biomarkers, including P21 and γH2AX. Interestingly, HLB01 promoted the expression of collagen in C. elegans and mammalian cell systemically, which might be one of the essential factors to exert the antiaging effects. In addition, HLB01 was also found as a scavenger of free radicals, thereby performing the antioxidant ability. Lifespan extension by HLB01 was also dependent on DAF-16 and HSF-1 via oxidative stress resistance and heat stress resistance. Taken together, overall data suggested that HLB01 could extend the lifespan and healthspan of C. elegans and resist Doxo-induced senescence in mice via promoting the expression of collagen, antioxidant potential, and stress resistance.

Trigonelline Extends the Lifespan of C. Elegans and Delays the Progression of Age-Related Diseases by Activating AMPK, DAF-16, and HSF-1.

Trigonelline is the main alkaloid with bioactivity presented in fenugreek, which was used in traditional medicine in Asian countries for centuries. It is reported that trigonelline has anti-inflammatory, anti-oxidant, and anti-pathogenic effects. We are wondering whether trigonelline have anti-aging effect. We found that 50 μM of trigonelline had the best anti-aging activity and could prolong the lifespan of Caenorhabditis elegans (C. elegans) by about 17.9%. Trigonelline can enhance the oxidative, heat, and pathogenic stress resistance of C. elegans. Trigonelline could also delay the development of neurodegenerative diseases, such as AD, PD, and HD, in models of C. elegans. Trigonelline could not prolong the lifespan of long-lived worms with loss-of-function mutations in genes regulating energy and nutrition, such as clk-1, isp-1, eat-2, and rsks-1. Trigonelline requires daf-16, hsf-1, and aak-2 to extend the lifespan of C. elegans. Trigonelline can also up-regulate the expression of daf-16 and hsf-1 targeted downstream genes, such as sod-3, gst-4, hsp-16.1, and hsp-12.6. Our results can be the basis for developing trigonelline-rich products with health benefits, as well as for further research on the pharmacological usage of trigonelline.

Polymorphism scanning of HSP90AB1 gene in local Friesian Holstein as molecular marker for heat stress resistance

Heat stress poses major problem in dairy cattle in term of reproduction and milk yield, especially in humid tropical climates. The HSP90AB1 is a gene that plays important role in heat stress response. Scanning its allele and genotype variation could be beneficial for the selection of dairy cattle which able to cope with heat stress effect. This study aimed to identify HSP90AB1 gene polymorphism (SNP g.4338T&gt;C) in Indonesian local Friesian Holstein dairy cattle population. In total 20 cattle were sampled randomly. In this study, AS-PCR was employed to amplify 561 bp of gene fragment, using pair of primer namely CF primer 5-CTGGAGTCACACTGAGGAAC-3, TF primer 5-CTGGAGTCACA CTGAGGAAT-3, F primer 5-CTGGAGTCACACTGAG-3, and R primer 5-TGTTGGAGATCGTCACCTG-3. As the results, allele T and C were observed, and respective frequencies are 0.35 and 0.65. Three genotypes of HSP90AB1 gene were found namely CC, CT, and TT. The respective genotype frequency is 0.1, 0.5, and 0.4. According to Hardy-Weinberg analysis, the population is in equilibrium (P&gt;0.05). It is concluded that CT genotype and T allele are the highest frequency in the sampled population. Further study needs to be performed to associate the genotype and allele variation to productivity trait of local dairy cattle.

Вплив прооксидантно-антиоксидантного гомеостазу на функціональну активність сперміїв кнурів за корекції мінерального живлення

The use of chelated compounds of trace elements as an alternative to mineral salts can increase their conversion, reduce the content in feed and prevent environmental pollution. However, it remains relevant to study the effect of these substances on the reproductive capacity of pigs. The aim of the study was to determine the effect of prooxidant-antioxidant homeostasis (PAH) on the functional activity of sperm of boars in the correction of mineral nutrition. The study used adult boars of the Large White breed. The duration of the experiment was 120 days, including: preparatory - 30, basic - 60 (feeding lactates of Zinc, Selenium, Copper and Iron) and final - 30 days. In the main period of the experiment, the diet of animals in the control group remained unchanged, and two experimental were with the addition of lactates Zinc, Selenium, Copper and Iron. The level of biologically active components in the diet of the experimental groups was higher by 10% and 20% compared with the control group. In the obtained blood samples it was determined the state of PAG. The functional activity of sperm in stored spermatozoa at 170C after 3 hours of incubation was determined by their activity and survival by testing for heat resistance, heat stress resistance, the number of anomalies and the integrity of acrosomes. It was found that the introduction of lactates of Zinc, Selenium, Copper and Iron in the feed mixture to boars significantly changes the state of PAG in blood depending on the number of additionally fed lactates of trace elements. The addition of these biologically active substances by 10% above the norm after 60 days of feeding helps to preserve the content of antioxidant vitamins, reduced glutathione, stimulates the functional activity of superoxide dismutase by 50% and catalase by 23.6% and is accompanied by a slight decrease in peroxidation processes. conjugates and TBC-active complexes. The addition of lactates of micronutrients to the feed mixture is by 20% more than norma for boars, compared with the control group, after 30 days of use stimulates peroxidation, accompanied by intensive use of non-enzymatic - vitamin A (p &lt;0,05-0,01) and activation of enzymatic antioxidants - superoxide dismutase (p &lt;0.05-0.01) and catalase, which lasts for 90 days. The viability of sperm is significantly correlated with the number of additionally fed lactates of trace elements. The addition of these biologically active substances by 10% more than normal after 60 days of feeding helps to increase the functional activity of sperm for 3 hours at a temperature of 170C storage, heat resistance (p &lt;0.05), heat stress resistance, increases their ability to fertilize. The addition of lactates of micronutrients in the feed mixture is by 20% more than the norm for boars in comparison with the control group after two months of feeding increases the number of pathological forms of sperm (p &lt;0,005), acrosome damage (p &lt;0,05), reduces heat resistance and heat stress resistance of sperm &lt;0.05), which reduces their fertility. It was found the fact that the processes of peroxidation in blood of boars are significantly interrelated with the functional activity of sperm in stored spermatozoa. The content of primary and secondary peroxidation products significantly correlates with the fertilizing ability of sperm in the range of r = 0.95… 0.99. The activity of superoxide dismutase and catalase are significantly interrelated with the fertilizing ability of sperm: in animals of the second group, the correlation coefficients were respectively r = 0.98 and r = 0.97, the third - r = 0.12 and r = 0.96, the first - r = - 0.58 and r = 0.80.

Mating under climate change: Impact of simulated heatwaves on the reproduction of model pollinators

Abstract Climate change is related to an increase in frequency and intensity of extreme events such as heatwaves. It is well established that such events may worsen the current world‐wide biodiversity decline. In many organisms, heat stress is associated with direct physiological perturbations and could lead to a decrease of fitness. In contrast to endotherms, heat stress resistance has been poorly investigated in heterotherms; especially in insects, in which the internal physiological mechanisms available to regulate body temperature are almost negligible making them sensitive to extreme temperature variations. Wild bees are crucial pollinators for wild plants and crops. Among them, bumblebees are experiencing a strong decline across the world. Therefore, the ongoing global decline of these insect pollinators partly due to climate change could cause major economic issues. Here we assess how simulated heatwaves impact fertility and attractiveness (key parameters of sustainability) of bumblebee males. We used three model species: Bombus terrestris, a widespread and warm‐adapted species, B. magnus and B. jonellus, two declining and cold‐adapted species. We highlight that heat shock (40°C) negatively affects sperm viability and sperm DNA integrity only in the two cold‐adapted species. Heat shock can also impact the structure of cephalic labial glands and the production of pheromones only in the declining species. The specific disruption in key reproductive traits we identify following simulated heatwave conditions could provide one important mechanistic explanation for why some pollinators are in decline through climate change. A free Plain Language Summary can be found within the Supporting Information of this article.

Novel approaches to mitigate heat stress impacts on crop growth and development

Heat stress is a major constraint to crop production and food security. The incidence of heat stress in crops has increased due to rapid changes in the global climate. Heat stress has a tremendous impact on crop growth and productivity due to its direct and indirect effects on water. Therefore, it is important to understand the morphological, physiological, biochemical, molecular, and ecological basis of heat stress in crop plants to minimize its impact on food production. Several genes alter their expression, proteins, and transcription factors to cope with heat stress. Adverse effects on macromolecules and genes change the signaling pathways for heat stress resistance. In the early phase of heat stress, plants regulate their immunity and plant nutrition management to alleviate the heat stress. All the self management of plants gets fail in severe heat stress situation to overcome from heat stress condition a judicious combination of conventional breeding and new technologies will help plants to cope efficiently with heat stress, including maintaining/enhancing yield to contribute to the nutritional requirements of the growing population. A better understanding of plant responses to heat stress has practical implications for remedies and management.

Evaluation of the Agronomic Traits of 80 Accessions of Proso Millet (Panicum miliaceum L.) under Mediterranean Pedoclimatic Conditions

The continuous increase in the world population and the associated food demands in the wake of climate change are pushing for the development and cultivation of climate-resilient crops that are able to efficiently use natural resources. Proso millet (Panicum miliaceum L.) might be a promising candidate crop thanks to its heat stress resistance and its limited water demand. To date, one of the most important strategies to increase grain yield and to improve other agronomic important traits is through an efficient breeding program based on a wide genetic variability of parental germplasm. In this study, we evaluated the agronomical traits of a world collection of 80 P. miliaceum accessions. The entire collection was evaluated over a 2 year field experiment under Mediterranean pedoclimatic conditions, which exhibited a wide range of variability for plant height (25–111 cm), grain yield (842–3125 kg ha−1), total dry biomass (2767–10,627 kg ha−1), harvest index (HI; 0.25–0.35), Growing Degree Days (GDDs; 581–899), and days to maturity (80–111 d). A non-parametric multivariate analysis of variance (Np-MANOVA) analysis indicated that GDDs to flowering, grain yield, total dry biomass, days to maturity, plant height, and seed yield per plant were useful parameters to differentiate the germplasm accessions. High heritability (&gt;0.60) was observed in both years for plant height, leaf number, basal tiller, seed yield per plant, 100-seed weight, GDDs to flowering, and days to maturity. Grain yield, total dry biomass, and HI reported moderate heritability (0.30–0.60). The findings reported in the present study may provide valuable information that could support researchers in breeding programs to develop high grain-yielding accessions.

Interactions with a Complex Microbiota Mediate a Trade-Off between the Host Development Rate and Heat Stress Resistance.

Animals and plants host diverse communities of microorganisms, and these microbiotas have been shown to influence host life history traits. Much has been said about the benefits that host-associated microbiotas bestow on the host. However, life history traits often demonstrate tradeoffs among one another. Raising Caenorhabditis elegans nematodes in compost microcosms emulating their natural environment, we examined how complex microbiotas affect host life history traits. We show that soil microbes usually increase the host development rate but decrease host resistance to heat stress, suggesting that interactions with complex microbiotas may mediate a tradeoff between host development and stress resistance. What element in these interactions is responsible for these effects is yet unknown, but experiments with live versus dead bacteria suggest that such effects may depend on bacterially provided signals.

Evolutionary history of the C-repeat binding factor/dehydration-responsive element-binding 1 (CBF/DREB1) protein family in 43 plant species and characterization of CBF/DREB1 proteins in Solanum tuberosum

BackgroundPlants are easily affected by temperature variations, and high temperature (heat stress) and low temperature (cold stress) will lead to poor plant development and reduce crop yields. Therefore, it is very important to identify resistance genes for improving the ability of plants to resist heat stress or cold stress by using modern biotechnology. Members of the C-repeat binding factor/Dehydration responsive element-binding 1 (CBF/DREB1) protein family are related to the stress resistance of many plant species. These proteins affect the growth and development of plants and play vital roles during environmental stress (cold, heat, drought, salt, etc.). In this study, we identified CBF/DREB1 genes from 43 plant species (including algae, moss, ferns, gymnosperms, angiosperms) by using bioinformatic methods to clarify the characteristics of the CBF/DREB1 protein family members and their functions in potato under heat and cold stresses.ResultsIn this study, we identified 292 CBF/DREB1 proteins from 43 plant species. However, no CBF/DREB1 protein was found in algae, moss, ferns, or gymnosperms; members of this protein family exist only in angiosperms. Phylogenetic analysis of all the CBF/DREB1 proteins revealed five independent groups. Among them, the genes of group I do not exist in eudicots and are found only in monocots, indicating that these genes have a special effect on monocots. The analysis of motifs, gene duplication events, and the expression data from the PGSC website revealed the gene structures, evolutionary relationships, and expression patterns of the CBF/DREB1 proteins. In addition, analysis of the transcript levels of the 8 CBF/DREB1 genes in potato (Solanum tuberosum) under low-temperature and high-temperature stresses showed that these genes were related to temperature stresses. In particular, the expression levels of StCBF3 and StCBF4 in the leaves, stems, and roots significantly increased under high-temperature conditions, which suggested that StCBF3 and StCBF4 may be closely related to heat tolerance in potato.ConclusionOverall, members of the CBF/DREB1 protein family exist only in angiosperms and plays an important role in the growth and development of plants. In addition, the CBF/DREB1 protein family is related to the heat and cold resistance of potato. Our research revealed the evolution of the CBF/DREB1 family, and is useful for studying the precise functions of the CBF/DREB1 proteins when the plants are developing and are under temperature stress.

A new adenylyl cyclase, putative disease resistance RPP13-like protein 3, participates in abscisic acid-mediated heat stress resistance in maize

A new adenylyl cyclase, putative disease resistance RPP13-like protein 3, participates in abscisic acid-mediated heat stress resistance in maize

Glucose Metabolism and Dynamics of Facilitative Glucose Transporters (GLUTs) under the Influence of Heat Stress in Dairy Cattle.

Heat stress is one of the main threats to dairy cow production; in order to resist heat stress, the animal exhibits a variety of physiological and hormonal responses driven by complex molecular mechanisms. Heat-stressed cows have high insulin activity, decreased non-esterified fatty acids, and increased glucose disposal. Glucose, as one of the important biochemical components of the energetic metabolism, is affected at multiple levels by the reciprocal changes in hormonal secretion and adipose metabolism under the influence of heat stress in dairy cattle. Therefore, alterations in glucose metabolism have negative consequences for the animal’s health, production, and reproduction under heat stress. Lactose is a major sugar of milk which is affected by the reshuffle of the whole-body energetic metabolism during heat stress, contributing towards milk production losses. Glucose homeostasis is maintained in the body by one of the glucose transporters’ family called facilitative glucose transporters (GLUTs encoded by SLC2A genes). Besides the glucose level, the GLUTs expression level is also significantly changed under the influence of heat stress. This review aims to describe the effect of heat stress on systemic glucose metabolism, facilitative glucose transporters, and its consequences on health and milk production.

Differential Dynamics of the Ruminal Microbiome of Jersey Cows in a Heat Stress Environment.

Simple SummaryRecently, it has become apparent that the microbiome is essential to health and affects practically every aspect of physiology. The rumen contains highly dense and diverse microbial communities, which can impact health through their composition, diversity, and assembly. Nevertheless, the diversity and function of rumen microbes have not been fully described. Therefore, this study aims to identify differences in the functional attributes and metabolites of rumen microbiota to heat stress by metagenomics and metabolomics analyses. We observed differences in biological changes, as well as changes in rumen metabolites and metabolic pathways depending on the breed of cow. In addition, significant changes in rumen bacterial taxa and functional gene abundance were observed. Overall, the findings of this study improve our understanding of heat-vulnerable ruminal bacteria and related genes.The microbial community within the rumen can be changed and shaped by heat stress. Accumulating data have suggested that different breeds of dairy cows have differential heat stress resistance; however, the underlying mechanism by which nonanimal factors contribute to heat stress are yet to be understood. This study is designed to determine changes in the rumen microbiome of Holstein and Jersey cows to normal and heat stress conditions. Under heat stress conditions, Holstein cows had a significantly higher respiration rate than Jersey cows. Heat stress increased the rectal temperature of Holstein but not Jersey cows. In the Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis, Jersey cows had a significantly higher proportion of genes associated with energy metabolism in the normal condition than that with other treatments. Linear discriminant analysis effect size (LEfSe) results identified six taxa as distinguishing taxa between normal and heat stress conditions in Holstein cows; in Jersey cows, 29 such taxa were identified. Changes in the rumen bacterial taxa were more sensitive to heat stress in Jersey cows than in Holstein cows, suggesting that the rumen mechanism is different in both breeds in adapting to heat stress. Collectively, distinct changes in rumen bacterial taxa and functional gene abundance in Jersey cows may be associated with better adaptation ability to heat stress.

Mutations in genes cnc or dKeap1 modulate stress resistance and metabolic processes in Drosophila melanogaster

The transcription factor Nrf2 and its negative regulator Keap1 play important roles in the maintenance of redox homeostasis in animal cells. Nrf2 activates defenses against oxidative stress and xenobiotics. Homologs of Nrf2 and Keap1 are present in Drosophila melanogaster (CncC and dKeap1, respectively). The aim of this study was to explore effects of CncC deficiency (due to mutation in the cnc gene) or enhanced activity (due to mutation in the dKeap1 gene) on redox status and energy metabolism of young adult flies in relation to behavioral traits and resistance to a number of stressors. Deficiency in either CncC or dKeap1 delayed pupation and increased climbing activity and heat stress resistance in 2-day-old adult flies. Males and females of the ∆keap1 line shared some similarities such as elevated antioxidant defense as well as lower triacylglyceride and higher glucose levels. Males of the ∆keap1 line also had a higher activity of hexokinase, whereas ∆keap1 females showed higher glycogen levels and lower values of respiratory control and ATP production than flies of the control line. Mutation of cnc gene in allele cncEY08884 caused by insertion of P{EPgy2} transposon in cnc promotor did not affect significantly the levels of metabolites and redox parameters, and even activated some components of antioxidant defense. These data suggest that the mutation can be hypomorphic as well as CncC protein can be dispensable for adult fruit flies under physiological conditions. In females, CncC mutation led to lower mitochondrial respiration, higher hexokinase activity and higher fecundity as compared with the control line. Either CncC activation or its deficiency affected stress resistance of flies.

Hyperthermic stress resistance of bumblebee males: test case of Belgian species

Thermotolerance has often been linked to species distribution for a diverse range of organisms. In the context of climate change, assessing heat resistance ability is useful for understanding potential future range shifts and the physiological response of populations. As bumblebee (Bombus) populations have been declining for several decades with several documented range shifts, an assessment of the hyperthermic resistance of species is urgently needed. In this study, we measure in males the heat resistance of ten bumblebee species living in temperate regions (northwestern Europe) with a static temperature methodology to evaluate the time before heat stupor (THS) which corresponds to a chill coma. Our results on heat stress resistance show that not all species are affected in the same way to heat stress. The most widespread species, B. terrestris (median THS 395 min) and B. lucorum (median THS 257 min) are the least sensitive to hyperthermic stress. The resistance time of bumblebee males is up to 10 times longer than the THS for declining species such as B. jonellus (median THS 48 min) and B. magnus (median THS 58 min). We highlight the high interspecific variability of heat resistance in a morphologically homogeneous genus such as bumblebees. From a conservation point of view, our research highlights the urgency for assessing the heat resistance of different species since each one can display a species-specific thermal sensitivity that is likely linked to a risk of decline in the case of heat waves.