Low Heat Stress Research Articles

The development of microencapsulated lactic acid bacteria and its application on yoghurt powder products

The probiotics were susceptible to damage in commercial starters due to improper environmental conditions. In this study, the encapsulation technique was applied to improve probiotics survival using alginate, inulin (commercial and beneng taro-source), skim milk and their combination; which is prepared by the extrusion method. The survival of encapsulated probiotics in adverse environmental conditions was investigated by exposing them to low pH and heat stress. The encapsulation yield and diameter of the encapsulated probiotics were also measured before their application to yoghurt powder. Both heat stress and pH 2 resulted in the decrease of the number of viable free cells and viable encapsulated cells by about 5 log cycles and 3 log cycles, respectively. The encapsulation yield was >98% in all treatments and the diameter of probiotics was increased significantly around >2.5 mm by the encapsulation method. The viability of the encapsulated probiotic cell was decreased 1 log cycle after applying in powdered yoghurt while without encapsulation the cell count was much lower. Thus, the microencapsulation method has proven as an effective protection technique against adverse environments, especially if applied as a powder product.

A surface quality optimization strategy based on a dedicated melt-pool control via the dashed-scan contouring technique in electron beam powder bed fusion

Electron beam powder bed fusion (EB-PBF) is a key metal additive manufacturing (AM) technology known for its high energy absorption and low heat stress. However, the high surface roughness of EB-PBF parts has limited its broader application. To address this issue, this paper proposes a dashed-scan contouring strategy to obtain lower surface roughness in EB-PBF. This strategy involves melting the contour in the form of segmented staggered scans and employing high-frequency jumping of the electron beam (EB) to melt multiple positions synchronously. A comprehensive analysis, combining experimental investigations and multi-physical simulations, elucidates the intrinsic connection between control processes and melt pool stability. Results show that by controlling the length-to-width ratio of the melt pool, regulating overlap distances between melt pools, and fine-tuning cooling times, balling phenomena and Plateau-Rayleigh instabilities can be suppressed. Additionally, these measures effectively mitigate irregularities in track formation when compared to the traditional process. Experimental validation demonstrates the efficacy of the approach, achieving reduced surface roughness (Ra) of thin-walled Ti-6Al-4 V parts from over 25 μm to below 12.6 μm, while enhancing dimensional accuracy and reducing melt anomalies at corners. The proposed dashed-scan contouring strategy opens new avenues for AM of highly reliable and intricate structures, such as lattice sandwich structures, thin walls, and internal flow passages.

Spatio-temporal urban land surface temperature variations and heat stress vulnerability index in Thiruvananthapuram city of Kerala, India

ABSTRACT Land use/Land cover (LU/LC) modifications leads to rise in surface temperature is a global concern. This study investigates the effects of LU/LC changes in Land Surface Temperature (LST) variations and effects of Urban Heat Island (UHI) in Thiruvananthapuram city. Furthermore, the study proposed a novel heat stress vulnerability index (HSVI) using Analytical Hierarchy Process (AHP) method. Results shows that transformation of all land uses is to built-up areas, which shows an increase of +118.46% where as others such as vegetation (-24.27%), open area (-64.315) and waterbody (-43.88%) shows drastic decrease over 34 years. The relationship between Normalized Difference Vegetation Index and LST shows a significant change with R2 values between 0.223 in 1988, 0.382 in 2000 and 0.253 in 2022. Moreover, this also contributed to the increase of the mean LST of 26.96 ºC in 1988 to 28.52 ºC in 2022. HSVI of the study indicates that 30.83% of the study area is categorized as very low heat stress vulnerable area followed by 37.22% area in low heat stress vulnerability, 17.88% in moderate heat stress vulnerability, 8.87% in high heat stress vulnerability and 5.19% of the area falling in very high heat stress Vulnerability class.

Identification and Analysis of the MIR399 Gene Family in Grapevine Reveal Their Potential Functions in Abiotic Stress.

MiR399 plays an important role in plant growth and development. The objective of the present study was to elucidate the evolutionary characteristics of the MIR399 gene family in grapevine and investigate its role in stress response. To comprehensively investigate the functions of miR399 in grapevine, nine members of the Vvi-MIR399 family were identified based on the genome, using a miRBase database search, located on four chromosomes (Chr 2, Chr 10, Chr 15, and Chr 16). The lengths of the Vvi-miR399 precursor sequences ranged from 82 to 122 nt and they formed stable stem-loop structures, indicating that they could produce microRNAs (miRNAs). Furthermore, our results suggested that the 2 to 20 nt region of miR399 mature sequences were relatively conserved among family members. Phylogenetic analysis revealed that the Vvi-MIR399 members of dicots (Arabidopsis, tomato, and sweet orange) and monocots (rice and grapevine) could be divided into three clades, and most of the Vvi-MIR399s were closely related to sweet orange in dicots. Promoter analysis of Vvi-MIR399s showed that the majority of the predicted cis-elements were related to stress response. A total of 66.7% (6/9) of the Vvi-MIR399 promoters harbored drought, GA, and SA response elements, and 44.4% (4/9) of the Vvi-MIRR399 promoters also presented elements involved in ABA and MeJA response. The expression trend of Vvi-MIR399s was consistent in different tissues, with the lowest expression level in mature and young fruits and the highest expression level in stems and young leaves. However, nine Vvi-MIR399s and four target genes showed different expression patterns when exposed to low light, high light, heat, cold, drought, and salt stress. Interestingly, a putative target of Vvi-MIR399 targeted multiple genes; for example, seven Vvi-MIR399s simultaneously targeted VIT_213s0067g03280.1. Furthermore, overexpression of Vvi_MIR399e and Vvi_MIR399f in Arabidopsis enhanced tolerance to drought compared with wild-type (WT). In contrast, the survival rate of Vvi_MIR399d-overexpressed plants were zero after drought stress. In conclusion, Vvi-MIR399e and Vvi-MIR399f, which are related to drought tolerance in grapevine, provide candidate genes for future drought resistance breeding.

Investigating outdoor thermal comfort variations across Local Climate Zones in Nagpur, India, using ENVI-met

Increasing temperatures are exacerbating the urban heat island effect within urban areas. As thermal stress rises in these environments, evaluating the variation in thermal comfort across the city is crucial for designing thermally comfortable spaces. Nagpur, a centrally located city in India experiences extreme thermal stress during the summer. The present study focuses on assessing the variation in thermal comfort using indices such as air temperature (AT), physiological equivalent temperature (PET), and universal thermal comfort index (UTCI) which acknowledge energy balance in the human body and its relationship with the outdoor environment. These indices are calculated across ten areas in the city, identified by Local Climate Zone (LCZ) using ENVI-met. The 24-h simulations revealed that open and vegetated urban areas (LCZ 6, 6B & A) present low heat stress during 14:00–15:00 and 03:00–04:00. However, sparsely built areas (LCZ 9 & 93) experience extreme thermal stress during daytime and moderate stress during nighttime. Densely built areas (LCZ 3 & 3F) present moderate thermal stress during the daytime and the highest during nighttime. Further, PET and UTCI percentile assessments revealed that sparsely built areas experience both extreme and neutral thermal stress. Compact areas stay moderately warm during nighttime. Vegetated areas experience moderately high thermal stress during the daytime and neutral to warm thermal stress during nighttime. The study highlights the need for more emphasis on nighttime thermal stress using ENVI-met to assess thermal conditions across various urban settings. This will contribute to a better understanding of climates and locations experiencing extreme thermal stress.

Thermal Comfort for various Altitudes and Land Covers in North Sumatra

Thermal comfort refers to the suitability of meteorological conditions for humans with the environment. Temperature is the main meteorological variable, which determines the thermal comfort as expressed in various climate indices. This study aims to analysis the distribution of thermal comfort, and to identify environmental factors influencing the comfort situated in North Sumatra, Indonesia. We applied the Universal Thermal Climate Index (UTCI) to determine the heat stress level for 2011 - 2020. The higher UTCI value indicates more uncomfortable conditions related to the higher heat stress. The results showed that the average value of UTCI in North Sumatra was categorised at moderate heat stress. Densely urbanised area in the eastern region contributed to high heat stress, whereas mountainous areas in central to west regions were at low level. Our findings found that climate season affected the distribution of heat stress level. The low heat stress occurred in December-February, while high heat stress happened in June-August. Further, findings revealed that altitude and land cover have contributed to UTCI variation by more than 75% variance.

Use of interpretive machine learning and a crop model to investigate the impact of environment and management on soybean yield gap

Context Management and environmental conditions are the main factors influencing yield of soybean (Glycine max (L.) Merr.). Despite an increase in average soybean yield in recent years in Iran, a considerable gap remains between actual yield and potential yield. Aims The objective of this study was to identify critical climate and management factors affecting soybean yield in Iran’s major soybean production area. Methods A combination of machine learning approaches (using gradient boosted decision trees, XGBoost) and the SSM-iCrop2 simulation model was used. Critical management factors affecting soybean yield were determined through interpretive machine learning using information collected from 268 soybean fields over a 5-year period. Potential yield and water-limited potential yield at six weather stations were estimated for 30 years via the SSM-iCrop2 simulation model. Water limitation was determined by considering the ratio of water-limited yield potential to potential yield, and heat stress status was quantified as the number of days with maximum temperature >36°C during the soybean growing season. Key results The XGBoost models adequately described the observed changes in soybean yield. Root-mean-square error and Lin’s concordance correlation coefficient values of the calibrated model were 262 kg ha−1 and 0.96, respectively, which indicated that the predictor variables could describe most of the variation in soybean yield for the studied dataset. Conclusions We identified 15 climatic and management variables that affect soybean yield. A large part of the studied area is under high water stress and low heat stress. Implications Optimal planting date and improved irrigation management are the main options for reducing the yield gap in the study area.

Planting Rice at Monsoon Onset Could Mitigate the Impact of Temperature Stress on Rice–Wheat Systems of Bihar, India

The rice–wheat rotation is the dominant cropping system in Bihar, where food security of the rural population depends heavily on the production of rice and wheat. In Bihar, farmers plant rice after the first significant rains, and climatic shocks induced by low temperatures and terminal heat stress at the end of the corresponding season can significantly affect rice and wheat yields. The present work evaluates the benefit of using an earlier date for planting rice, following the monsoon onset, in reducing thermal stress on rice–wheat systems. High-resolution gridded crop simulations using the APSIM model were performed to simulate potential yields using the monsoon onset and the farmers’ practice as planting dates. The monsoon onset was calculated using an agronomic definition, and farmers’ practice dates were estimated using satellite data. The results were analyzed in terms of planting dates, yields, and the incidence of temperature stress on rice and wheat by means of the APSIM yields limiting factors. The results show that the rice planting and harvest dates using the monsoon onset are, in general, 20–30 days earlier, which translates into higher and more stable potential yields, which can be up to 50% higher in wheat and 29% in rice. The incidence of thermal stress can be, on average, 12% lower in rice and 25% in wheat. These results can help design mitigation strategies for the impacts of temperature-induced shock events in the context of the advances in sub-seasonal and seasonal forecasting, targeting climate services for farmers in Bihar.

Effects of Dietary Supplementation of Solubles from Shredded, Steam-Exploded Pine Particles on the Performance and Cecum Microbiota of Acute Heat-Stressed Broilers.

Heat stress (HS) negatively influences livestock productivity, but it can be, at least in part, mitigated by nutritional interventions. One such intervention is to use byproducts from various sources that are likely to be included in the consumer chain. Thus, the present study investigated the effects of dietary supplementation of solubles from shredded, steam-exploded pine particles (SSPPs) on the performance and cecum microbiota in broilers subjected to acute HS. One-week-old Ross 308 broilers (n = 108) were fed 0%, 0.1%, or 0.4% SSPP in their diets. On the 37th day, forty birds were allocated to one of four groups; namely, a group fed a control diet without SSPPs at thermoneutral temperature (NT) (0% NT) and acute heat-stressed birds with 0% (0% HS), 0.1% (0.1% HS), and 0.4% (0.4% HS) SSPP-supplemented diets. The NT was maintained at 21.0 °C, while the HS room was increased to 31 °C. The final BW, percent difference in body weight (PDBW), and feed intake (FI) were lower in HS birds, but PDBW was reversely associated with dietary SSPP. Similarly, HS birds had a higher rectal temperature (RT) and ΔT in comparison to birds kept at NT. The FI of SSPP-supplemented birds was not significant, indicating lower HS effects. Plasma triglyceride was decreased in HS birds but not affected in 0.1% HS birds in comparison to 0% NT birds. OTUs and Chao1 were increased by 0.1% HS compared to 0% NT. Unweighted Unifrac distances for 0.1% HS were different from 0% NT and 0.4% HS. The favorable bacterial phylum (Tenericutes) and genera (Faecalibacterium and Anaerofustis) were increased, while the pathogenic genus (Enterococcus) was decreased, in SSPP-supplemented birds. In sum, production performances are negatively affected under acute HS. Dietary supplementation of SSPPs is beneficial for improving community richness indices and unweighted Unifrac distances, and it enhanced the advantageous bacterial phyla and reduced virulent genera and triglyceride hydrolysis in acute HS broilers. Our results indicate that dietary SSPPs modulates the microbial profile of the cecum while resulting in relatively less weight loss and lower rectal temperature compared to control.

Predicting Maize (Zea mays) productivity under projected climate change with management options in Amhara region, Ethiopia

Maize is an important cereal crop in Ethiopia. Maize yield has been declined in Ethiopia mainly due to water scarcity, low soil fertility and heat stress. Currently, limited technologies are available in the study region that increases maize productivity. If crop models are properly calibrated, they are effective tools to study crops responses to environmental factors. Assessing impact of future climate on maize crop may help to develop adaptation strategies. The objectives of this study were (1) to calibrate and evaluate the CERES maize model in DSSAT technology for simulating phenology and yield of maize (2) to assess impact of projected climate change on maize productivity (3) to develop promising management practices for maize. The impact of projected climate change was assessed using the 17 GCMs (CMIP5) run under RCP4.5 and RCP8.5 climate scenarios. Two water regimes treatments (rainfed and irrigated) and four rates of nitrogen (0, 46, 92 and 138 kg ha−1) were evaluated individually and in combinations for their effectiveness to increase maize productivity under the projected climate conditions. The model evaluation result revealed that the RMSE values were 2.5 days for anthesis, 4.4 days for physiological maturity, 258.3 kg ha−1 for grain yield and 1034 kg ha−1for above ground biomass yield with nRMSE values of 3%, 4%, 4.7% and 10%, respectively. The d-index values were 0.87, 0.80, 0.88 and 0.71 for the respective parameters. The good agreement between the simulated and the measured values indicated the maize genetic coefficients in the model were properly calibrated. The simulation results at Tehuledere site showed that maize grain yield may decrease by 11% and 20% in 2030s and by 26% and 29% in 2050s under RCP4.5 and RCP8.5 scenarios, respectively whereas in Kallu site yield may decrease by 13% and 15% in 2030s and by 17% and 19% in 2050s for the respective RCP scenarios. However, the management scenarios have shown that maize yield may substantially increase by the use of optimum nitrogen fertilizer and supplemental irrigation. Thus, it can be generalized that climate change may adversely affect maize production in the Semi-arid regions of Ethiopia but the impact could be reversed by using sound crop management practices.

Identification of <I>PPARGC1A</I>-regulated oxidative phosphorylation pathway showing heat stress-responsive activation associated with low heat stress tolerance for growth rate in skeletal muscle tissue of finishing pig

Identification of <I>PPARGC1A</I>-regulated oxidative phosphorylation pathway showing heat stress-responsive activation associated with low heat stress tolerance for growth rate in skeletal muscle tissue of finishing pig

Within-subject variation of technical performance in elite Brazilian professional soccer players: the environmental stress, match location, and opposition’s ranking influences

ABSTRACT Recent research identified that the behaviour of players and teams varies depending on the match context affecting the players’ technical performance. Due to the high context variability of a soccer game, understanding the characteristics of technical performance in soccer can enable coaches to make better decisions. The present study aimed to evaluate the effects of environmental stress, match location, and opposition’s ranking on technical performance variation of elite soccer players from strong and weak teams from the Brasileirão Serie A (Brazilian First Division National Championship). Fourteen match actions were chosen as dependent variables in the analysis. Values of each action of each player per match were established. We compared the means of these values from the Top 4 and Bottom 4 teams across different match contexts (environment heat stress, match location, and opposition’s ranking). We calculated all comparisons using linear mixed models. The results showed better technical performance under low or medium environmental heat stress at home and against weak opposition (p < 0.05). Therefore, match context affects elite Brazilian soccer players’ technical performance from the first division championship.

Inhibitory effect of a new bacteriocin RSQ04 purified from Lactococcus lactis on Listeria monocytogenes and its application on model food systems

Listeria monocytogenes and its biofilms can constitute a severe threat to public health. RSQ04 is a novel bacteriocin produced by Lactococcus lactis CGMCC20699 against L. monocytogenes ATCC 19115. Molecular mass and amino acid sequence of RSQ04 were, respectively, 1164.55 Da and NGNGAAPAAASPAP. RSQ04 exhibited excellent stability during storage and adverse conditions such as low temperature, heat, and acid stress. Growth and biofilm formation of L. monocytogenes_15 planktonic cells were significantly (p < 0.05) inhibited after treatment with RSQ04. Scanning electron microscopy analysis revealed that cellular structure of L. monocytogenes_15 was disrupted by RSQ04 due to pore formation on the cell membrane. Hemolytic and cytotoxicity activity on HEK293T cells as well as in vivo evaluation in Kunming mice confirmed safety of RSQ04. Moreover, antibiofilm activity of RSQ04 was confirmed against L. monocytogenes_15 onto abiotic (stainless steel) and biotic surfaces (chicken breast and Italian ham). These findings indicate that RSQ04 could be used as a potential food biopreservative to control contamination by L. monocytogenes. This study systematically investigated RSQ04 from purification, characterization, safety assessment, and practical application on model food systems, providing an example for development and utilization of bacteriocins in food industries.

Determinants of Hypertension amongst Rice Farmers in West Java, Indonesia.

The hypertension rate in Indonesia has increased significantly in the past five years, but there is limited information about the hypertension risk of farmers. Our study assesses the prevalence of hypertension in this population and examines the proportional risk of various work environment and lifestyle factors among farmers. A cross-sectional study was conducted in high and low heat stress agriculture areas of West Java, Indonesia. There were 354 male farmers aged 25 to 73 years old who participated in the study. We measured blood pressure and used a questionnaire on self-reported use of anti-hypertension drugs or diagnosis by a medical professional to define hypertension. We assessed occupational factors including farming methods, heat stress and pesticide use, and personal factors including obesity, food intake, smoking status, alcohol consumption. Multivariate analysis was used to evaluate factors potentially associated with prevalence of hypertension. Forty-six percent of farmers experience hypertension. Farming in a location with higher heat stress (WBGT) was significantly associated with increased risk of hypertension (adjusted prevalence ratio (aPR) 1.41, 95% confidence interval (CI) 1.01, 1.95). Farmers who used pesticide sprayers had an increased risk of hypertension (aPR 1.90, 95% CI 0.93, 3.87). No personal/lifestyle characteristics were significantly associated with hypertension, although ever smoking and ever consuming alcohol had an increased prevalence of hypertension. This study shows the importance of work environmental factors in the prevalence of hypertension and the necessity of public health education, identification and treatment of this “silent killer” among Indonesian farmers.

Season specific feed formulations for ameliorating climate stress in grower pigs reared under subtropical eastern Himalayan region

Thermal stress is an emerging issue for pig producers in tropical and sub-tropical Eastern Himalayan region. Thus, season specific feed was proposed to be formulated for amelioration thermal stress. Feeding experiment were conducted for both summer stress (May-August) and winter stress (November-February) in grower pigs (75% Hampshire and 25% Niang Megha). Forty-eight piglets for each experiment were selected and distributed by completely randomized design for these two experiments. The seasonal specific feed as well as standard feed were formulated and provided to the piglets as per the standard procedures. Blood cortisol was measured as indicator of stress, besides the body weight gain, average daily gain and feed conservation efficiency in the pigs. Results indicated that the grower pigs fed with summer specific feed had significantly (P<0.05) lower heat stress, higher body weight gain and better feed conversion ratio as compared to grower pigs fed with standard diet during summer season. Similarly, feeding of winter specific feed has significantly (P<0.05) lowered the cortisol level, improved the body weight gain and better feed conversion ratio in grower pigs. The study concluded that the feeding of season specific diet reduced thermal stress and improved body weight gain in growing pigs. Thus, season specific feed formulations are suggested as one of the strategies to alleviate thermal stress in the region under changing climate condition.

Isoprene emission characteristics of tall and dwarf bamboos

Considerable isoprene emissions from several bamboo species have been reported. However, bamboos are highly diverse in taxonomy and have different niches or habitats among species, and the present investigation might be insufficient to conclude a representative isoprene emission trait for bamboos. In this study, isoprene flux, leaf mass per area (LMA), photosynthetic rate, and electron transport rate (ETR) observations were conducted for 18 species within five genera of bamboo species, which include different growth types (tall and dwarf) and climates of the region of origin (temperate, warm-temperate, and subtropical). As a result, we observed that dwarf bamboos exhibited very low or no emission; in contrast, tall bamboos demonstrated considerable isoprene emission fluxes mainly in August and September 2019 at temperatures greater than 30 °C. For tall bamboos, isoprene emission fluxes, photosynthetic rate, and ETR in area-based units were correlated with LMA. To exclude the systematic correlation among isoprene emission flux, photosynthetic rate, and ETR, correlations among the observations of mass-based units were also tested, and the results demonstrated significant positive correlations. The distinction in isoprene emission traits between tall and dwarf bamboos was independent of LMA, photosynthetic rate, and ETR, as there was no difference between them. This implies that the distinction in isoprene emission was caused by genetic differences. The low emission of isoprene from the dwarf species is reasonable because dwarf bamboos usually grow in areas with relatively low heat stress and low light where the production of isoprene could be futile due to carbon loss. This study suggests separating the two bamboo types into different functional types of isoprene emissions. • Isoprene emission flux from leaves of 18 bamboo species were observed. • Dwarf bamboos exhibited almost no isoprene emission. • Tall bamboos exhibited remarkably large isoprene flux in summer. • Dependences on LMA and ETR were observed across the tall bamboos.

A constitutive stress response is a result of low temperature growth in the Antarctic green alga Chlamydomonas sp. UWO241.

The Antarctic green alga Chlamydomonas sp. UWO241 is an obligate psychrophile that thrives in the cold (4-6°C) but is unable to survive at temperatures ≥18°C. Little is known how exposure to heat affects its physiology or whether it mounts a heat stress response in a manner comparable to mesophiles. Here, we dissect the responses of UWO241 to temperature stress by examining its growth, primary metabolome and transcriptome under steady-state low temperature and heat stress conditions. In comparison with Chlamydomonas reinhardtii, UWO241 constitutively accumulates metabolites and proteins commonly considered as stress markers, including soluble sugars, antioxidants, polyamines, and heat shock proteins to ensure efficient protein folding at low temperatures. We propose that this results from life at extreme conditions. A shift from 4°C to a non-permissive temperature of 24°C alters the UWO241 primary metabolome and transcriptome, but growth of UWO241 at higher permissive temperatures (10 and 15°C) does not provide enhanced heat protection. UWO241 also fails to induce the accumulation of HSPs when exposed to heat, suggesting that it has lost the ability to fine-tune its heat stress response. Our work adds to the growing body of research on temperature stress in psychrophiles, many of which are threatened by climate change.

Bioprospecting Desert Plants for Endophytic and Biostimulant Microbes: A Strategy for Enhancing Agricultural Production in a Hotter, Drier Future.

Simple SummaryEndophytes are microbes that live inside plants without causing negative effects in their hosts. All land plants are known to have endophytes, and these endophytes have the capacity to be transferred between plants. Taking endophytes from desert plants, which grow in low-nutrient, high-stress environments, and transferring them to crop plants may alleviate some of the challenges being faced by the agricultural industry, such as increasing drought frequency and rising opposition to chemical use in agriculture. Studies have shown that desert endophytes have the capacity to increase nutrient uptake and increase plant resistance to drought and heat stress, salt stress, and pathogen attack. Currently, the agricultural industry focuses on using irrigation, chemical fertilizers, and chemical pesticides to solve such issues, which can be extremely damaging to the environment. While there is still a lot that is unknown about endophytes, particularly desert plant endophytes, current research provides evidence that desert plant endophytes could be an environmentally friendly alternative to the conventional solutions being applied today.Deserts are challenging places for plants to survive in due to low nutrient availability, drought and heat stress, water stress, and herbivory. Endophytes—microbes that colonize and infect plant tissues without causing apparent disease—may contribute to plant success in such harsh environments. Current knowledge of desert plant endophytes is limited, but studies performed so far reveal that they can improve host nutrient acquisition, increase host tolerance to abiotic stresses, and increase host resistance to biotic stresses. When considered in combination with their broad host range and high colonization rate, there is great potential for desert endophytes to be used in a commercial agricultural setting, especially as croplands face more frequent and severe droughts due to climate change and as the agricultural industry faces mounting pressure to break away from agrochemicals towards more environmentally friendly alternatives. Much is still unknown about desert endophytes, but future studies may prove fruitful for the discovery of new endophyte-based biofertilizers, biocontrol agents, and abiotic stress relievers of crops.

Selenium Deficiency Aggravates Heat Stress Pneumonia in Chickens by Disrupting the M1/M2 Balance

Selenium (Se) is an essential trace element found in the body. Se deficiency and M1/M2 imbalance are closely related to inflammation. Heat stress can decrease immune function and cause inflammation. In order to investigate whether Se deficiency can aggravate pneumonia caused by heat stress and the role of M1/M2 imbalance in the occurrence of pneumonia, 100 AA broilers were divided into two groups and fed the conventional diet (0.2mg/kg Se) and the Se-deficient diet (0.03mg/kg Se). After 40days of feeding, the normal feeding group was randomly divided into a control group and a heat stress group. At the same time, the Se-deficient diet feeding group was randomly divided into a low Se group and a low Se heat stress group, with 25 chickens in each group. The model was established by exposure at 40℃. Six hours later, broilers were euthanized, and their lung tissues were collected. Hematoxylin and eosin staining, immunofluorescence, quantitative real-time PCR, and western blotting were used to detect lung histopathological changes and the expression of M1/M2 markers, nuclear receptor-κB (NF-κB) pathway genes, and heat shock proteins. Meanwhile, the activity and content of oxidative stress-related indices were also detected. We found that the expression of interleukin-1β, interleukin-6, interleukin-12, and tumor necrosis factor-α was upregulated and the expression of interleukin-2, interleukin-10, and interferon-γ was downregulated. Immunofluorescence showed that the expression of CD16 was increased, the expression of CD163 was weakened, and the M1/M2 imbalance was present. In addition, the NF-κB pathway was activated by the increased expressions of heat shock proteins and oxidative stress. There was an increase in malondialdehyde, nitric oxide, and inducible nitric oxide synthase content, while the activity of total antioxidant capacity, glutathione peroxidase, catalase, and superoxide dismutase decreased, and the expression of NF-κB and cyclooxygenase-2 increased. These results suggest that low Se induces M1/M2 imbalance through oxidative stress activation of the NF-κB pathway and aggravates lung tissue inflammation caused by heat stress. This study offers a theoretical basis for exploring the pathogenesis of various kinds of inflammation induced by Se deficiency from the perspective of M1/M2 and provides a reference for the prevention of such diseases.

Influence of Prescribed Burning on a Pinus nigra subsp. Laricio Forest: Heat Transfer and Tree Vitality

Surface fuel removal is crucial to facilitate the mitigation of severe fires in forests. Prescribed burning is often used by forest managers, thanks to its low cost and high efficiency in hard-to-reach areas. The determination of heat transfer between fires and trees has rarely been carried out on living species and consequently, their long-term effects on tree physiology are still not fully understood. In this study, a multidisciplinary approach was conducted to evaluate the impact of a late spring (June) prescribed burning on a Mediterranean pine forest (Pinus nigra subsp. laricio). The surface fuels consisted of a 656 g m−² needle litter, mixed with a few scattered living herbaceous strata. During the fire spread, measurements of the inner and outer trunk temperatures were made at the base of 12 trees with an average bark thickness of 19.4 ± 7.0 mm. The fireline intensity and flame residence time were in the range of 110–160 kW m−1 and 220–468 s, respectively. Despite a maximum heating rate at the cambial area of 4.37 °C min−1, the temperature of these tissues remained below 60 °C, a critical threshold above which thermal damage will occur. In addition, prior- and post-fire physiological monitoring was performed over a long time period (2.5 years) on 24 trees, using sap flow, chlorophyll fluorescence and gas exchange measurements. All parameters remain highly correlated and indicate that the burned trees did not suffer physiological damage. Moreover, drought resistance strategies were not altered by the prescribed burning. The thermal insulation capability of the bark allowed the functional tissues to experience low heat stress that did not affect tree vitality.