Cold Exposure Research Articles

Preconceptional capsaicin intervention mitigates negative effects of paternal obesity on metabolic characteristics in male offspring upon high-fat diet challenge

The activation of brown adipose tissue by cold exposure in paternal mice has been reported to improve the metabolic health of offspring. Notably, dietary components for activating BAT have drawn considerable attention owing to their high feasibility for human trials. Therefore, here the potential metabolic improving effects of dietary capsaicin intervention on diet-induced obese paternal mice and their offspring were measured. The results support that paternal preconceptional capsaicin intervention not only elicited the anticipated enhancement of brown fat activity in obese paternal mice, but also improved the metabolic profiles in male offspring evidenced by their elevated resistance to high-fat diet challenge. Moreover, changes in sperm DNA methylation and small non-coding RNA profile were noted in paternal mice with capsaicin intervention, though additional investigation is needed to further delve into the mechanisms. In summary, paternal dietary intervention activating BAT could represent a promising strategy for enhancing the metabolic health of offspring.

Cold stress induces rapid gene-specific changes in the levels of H3K4me3 and H3K27me3 in Arabidopsis thaliana

When exposed to low temperatures, plants undergo a drastic reprogramming of their transcriptome in order to adapt to their new environmental conditions, which primes them for potential freezing temperatures. While the involvement of transcription factors in this process, termed cold acclimation, has been deeply investigated, the potential contribution of chromatin regulation remains largely unclear. A large proportion of cold-inducible genes carries the repressive mark histone 3 lysine 27 trimethylation (H3K27me3), which has been hypothesized as maintaining them in a silenced state in the absence of stress, but which would need to be removed or counteracted upon stress perception. However, the fate of H3K27me3 during cold exposure has not been studied genome-wide. In this study, we offer an epigenome profiling of H3K27me3 and its antagonistic active mark H3K4me3 during short-term cold exposure. Both chromatin marks undergo rapid redistribution upon cold exposure, however, the gene sets undergoing H3K4me3 or H3K27me3 differential methylation are distinct, refuting the simplistic idea that gene activation relies on a switch from an H3K27me3 repressed chromatin to an active form enriched in H3K4me3. Coupling the ChIP-seq experiments with transcriptome profiling reveals that differential histone methylation only weakly correlates with changes in expression. Interestingly, only a subset of cold-regulated genes lose H3K27me3 during their induction, indicating that H3K27me3 is not an obstacle to transcriptional activation. In the H3K27me3 methyltransferase curly leaf (clf) mutant, many cold regulated genes display reduced H3K27me3 levels but their transcriptional activity is not altered prior or during a cold exposure, suggesting that H3K27me3 may serve a more intricate role in the cold response than simply repressing the cold-inducible genes in naïve conditions.

The Different Shades of Thermogenic Adipose Tissue.

By providing a concise overview of adipose tissue types, elucidating the regulation of adipose thermogenic capacity in both physiological contexts and chronic wasting diseases (a protracted hypermetabolic state that precipitates sustained catabolism and consequent progressive corporeal atrophy), and most importantly, delving into the ongoing discourse regarding the role of adipose tissue thermogenic activation in chronic wasting diseases, this review aims to provide researchers with a comprehensive understanding of the field. Adipose tissue, traditionally classified as white, brown, and beige (brite) based on its thermogenic activity and potential, is intricately regulated by complex mechanisms in response to exercise or cold exposure. This regulation is adipose depot-specific and dependent on the duration of exposure. Excessive thermogenic activation of adipose tissue has been observed in chronic wasting diseases and has been considered a pathological factor that accelerates disease progression. However, this conclusion may be confounded by the detrimental effects of excessive lipolysis. Recent research also suggests that such activation may play a beneficial role in the early stages of chronic wasting disease and provide potential therapeutic effects. A more comprehensive understanding of the changes in adipose tissue thermogenesis under physiological and pathological conditions, as well as the underlying regulatory mechanisms, is essential for the development of novel interventions to improve health and prevent disease.

Cold-stress induced metabolomic and transcriptomic changes in leaves of three mango varieties with different cold tolerance

BackgroundMango (Mangifera indica L.) is grown in Hainan, Guangdong, Yunnan, Sichuan, and Fujian provinces and Guanxi autonomous region of China. However, trees growing in these areas suffer severe cold stress during winter, which affects the yield. To this regard, data on global metabolome and transcriptome profiles of leaves are limited. Here, we used combined metabolome and transcriptome analyses of leaves of three mango cultivars with different cold stress tolerance, i.e. Jinhuang (J)—tolerant, Tainung (T) and Guiremang No. 82 (G)—susceptible, after 24 (LF), 48 (MF) and 72 (HF) hours of cold.ResultsA total of 1,323 metabolites belonging to 12 compound classes were detected. Of these, amino acids and derivatives, nucleotides and derivatives, and lipids accumulated in higher quantities after cold stress exposure in the three cultivars. Notably, Jinhuang leaves showed increasing accumulation trends of flavonoids, terpenoids, lignans and coumarins, and alkaloids with exposure time. Among the phytohormones, jasmonic acid and abscisic acid levels decreased, while N6-isopentenyladenine increased with cold stress time. Transcriptome analysis led to the identification of 22,526 differentially expressed genes. Many genes enriched in photosynthesis, antenna proteins, flavonoid, terpenoid (di- and sesquiterpenoids) and alkaloid biosynthesis pathways were upregulated in Jihuang leaves. Moreover, expression changes related to phytohormones, MAPK (including calcium and H2O2), and the ICE-CBF-COR signalling cascade indicate involvement of these pathways in cold stress responses.ConclusionCold stress tolerance in mango leaves is associated with regulation of primary and secondary metabolite biosynthesis pathways. Jasmonic acid, abscisic acid, and cytokinins are potential regulators of cold stress responses in mango leaves.

Irisin influences the in vitro differentiation of human mesenchymal stromal cells, promoting a tendency towardbeiging adipogenesis.

Mammals exhibit two distinct types of adipose depots: white adipose tissue (WAT)and brown adipose tissue (BAT).While WAT primarily functions as a site for energy storage, BAT serves as a thermogenic tissue that utilizes energy and glucose consumption to regulate core body temperature. Under specific stimuli such as exercise, cold exposure, and drug treatment, white adipocytes possess a remarkable ability to undergo transdifferentiation into brown-like cells known as beige adipocytes. This transformation process, known as the "browning of WAT," leads to the acquisition of new morphological and physiological characteristics by white adipocytes. We investigated the potential role of Irisin, a 12 kDa myokine that is secreted in mice and humans by skeletal muscle after physical activity, in inducing the browning process in mesenchymal stromal cells (MSCs). A subset of the MSCs possesses the remarkable capability to differentiate into different cell types such as adipocytes, osteocytes, and chondrocytes. Consequently, comprehending the effects of Irisin on MSC biology becomes a crucial factor in investigating antiobesity medications. In our study, the primary objective is to evaluate the impact of Irisin on various cell types engaged in distinct stages of the differentiation process, including stem cells, committed precursors, and preadipocytes. By analyzing the effects of Irisin on these specific cell populations, our aim is to gain a comprehensive understanding of its influence throughout the entire differentiation process, rather than solely concentrating on the final differentiated cells. This approach enables us to obtain insights into the broader effects of Irisin on the cellular dynamics and mechanisms involved in adipogenesis.

Glucose regulation of adipose tissue browning by CBP/p300- and HDAC3-mediated reversible acetylation of CREBZF

Glucose is required for generating heat during cold-induced nonshivering thermogenesis in adipose tissue, but the regulatory mechanism is largely unknown. CREBZF has emerged as a critical mechanism for metabolic dysfunction-associated steatotic liver disease (MASLD), formerly known as nonalcoholic fatty liver disease (NAFLD). We investigated the roles of CREBZF in the control of thermogenesis and energy metabolism. Glucose induces CREBZF in human white adipose tissue (WAT) and inguinal WAT (iWAT) in mice. Lys208 acetylation modulated by transacetylase CREB-binding protein/p300 and deacetylase HDAC3 is required for glucose-induced reduction of proteasomal degradation and augmentation of protein stability of CREBZF. Glucose induces rectal temperature and thermogenesis in white adipose of control mice, which is further potentiated in adipose-specific CREBZF knockout (CREBZF FKO) mice. During cold exposure, CREBZF FKO mice display enhanced thermogenic gene expression, browning of iWAT, and adaptive thermogenesis. CREBZF associates with PGC-1α to repress thermogenic gene expression. Expression levels of CREBZF are negatively correlated with UCP1 in human adipose tissues and increased in WAT of obese ob/ob mice, which may underscore the potential role of CREBZF in the development of compromised thermogenic capability under hyperglycemic conditions. Our results reveal an important mechanism of glucose sensing and thermogenic inactivation through reversible acetylation.

Dietary fat supplementation relieves cold temperature-induced energy stress through AMPK-mediated mitochondrial homeostasis in pigs.

Cold stress has negative effects on the growth and health of mammals, and has become a factor restricting livestock development at high latitudes and on plateaus. The gut-liver axis is central to energy metabolism, and the mechanisms by which it regulates host energy metabolism at cold temperatures have rarely been illustrated. In this study, we evaluated the status of glycolipid metabolism and oxidative stress in pigs based on the gut-liver axis and propose that AMP-activated protein kinase (AMPK) is a key target for alleviating energy stress at cold temperatures by dietary fat supplementation. Dietary fat supplementation alleviated the negative effects of cold temperatures on growth performance and digestive enzymes, while hormonal homeostasis was also restored. Moreover, cold temperature exposure increased glucose transport in the jejunum. In contrast, we observed abnormalities in lipid metabolism, which was characterized by the accumulation of bile acids in the ileum and plasma. In addition, the results of the ileal metabolomic analysis were consistent with the energy metabolism measurements in the jejunum, and dietary fat supplementation increased the activity of the mitochondrial respiratory chain and lipid metabolism. As the central nexus of energy metabolism, the state of glycolipid metabolism and oxidative stress in the liver are inconsistent with that in the small intestine. Specifically, we found that cold temperature exposure increased glucose transport in the liver, which fully validates the idea that hormones can act on the liver to regulate glucose output. Additionally, dietary fat supplementation inhibited glucose transport and glycolysis, but increased gluconeogenesis, bile acid cycling, and lipid metabolism. Sustained activation of AMPK, which an energy receptor and regulator, leads to oxidative stress and apoptosis in the liver; dietary fat supplementation alleviates energy stress by reducing AMPK phosphorylation. Cold stress reduced the growth performance and aggravated glycolipid metabolism disorders and oxidative stress damage in pigs. Dietary fat supplementation improved growth performance and alleviated cold temperature-induced energy stress through AMPK-mediated mitochondrial homeostasis. In this study, we highlight the importance of AMPK in dietary fat supplementation-mediated alleviation of host energy stress in response to environmental changes.

Cold tolerance of the mealybug parasitoid Anagyrus vladimiri

AbstractWe investigated the lower thermal limits of Anagyrus vladimiri Triapitsyn (Hymenoptera: Encyrtidae), a natural enemy of mealybugs. Parasitoids were cooled to measure supercooling points and the lower lethal temperature LLT50. To investigate survival after long-term cold exposure, parasitoid adults and eggs, larvae, and pupae within their host mummy were gradually acclimated. Adults were then exposed for three days to 7 °C, 5 °C, 3 °C, and 1 °C, and immatures for varying durations to 5, 1, and − 4 °C. Parasitoids were investigated for survival and reproduction. To assess the impact of fluctuating temperature, parasitoid pupae were subjected to daily warming to 10 °C from baseline temperatures of 5 °C, 1 °C, and − 4 °C during four-day-cold exposure. Finally, eggs, pupae and adults were exposed to winter conditions in Switzerland in a semi-field setup. The LLT50 was − 17.24 °C for adults and 0.94 °C for pupae. Both values were above the supercooling points. No adult survived three days at 3 °C and lower. Likewise, no emergence occurred from eggs or larvae exposed for four days and longer to 1 °C or seven days to 5 °C. Pupae were cold-hardier surviving seven days at 5 °C and three days at 1 °C. Parasitoids surviving cold exposure were still able to reproduce. Daily warming decreased emergence of cold exposed pupae at a baseline temperature of 1 °C but not at 5 °C and − 4 °C. No eggs, pupae and adults survived winter conditions in the semi-field experiment. We thus consider A. vladimiri a chill-susceptible species with very limited cold-tolerance of the investigated population and low chances of survival during winter in Northern Switzerland.

Trends in emergency department visits during cold weather seasons among patients experiencing homelessness in Ontario, Canada: a retrospective population-based cohort study.

Recent anecdotal reports suggest increasing numbers of people experiencing homelessness are visiting emergency departments (EDs) during cold weather seasons due to inadequate shelter availability. We examined monthly ED visits among patients experiencing homelessness to determine whether there has been a significant increase in such visits in 2022/2023 compared to prior years. We used linked health administrative data to identify cohorts experiencing homelessness in Ontario between October and March of the 2018/2019 to 2022/2023years. We analyzed the monthly rate of non-urgent ED visits as a proxy measure of visits plausibly attributable to avoidance of cold exposure, examining rates among patients experiencing homelessness compared to housed patients. We excluded visits for overdose or COVID-19. We assessed level and significance of change in the 2022/2023year as compared to previous cold weather seasons using Poisson regression. We identified a total of 21,588 non-urgent ED visits across the observation period among patients experiencing homelessness in Ontario. Non-urgent ED visits increased 27% (RR 1.24 [95% CI 1.14-1.34]) in 2022/2023 compared to previous cold weather seasons. In Toronto, such visits increased by 70% (RR 1.68 [95% CI 1.57-1.80]). Among housed patients, non-urgent ED visits did not change significantly during this time period. Rates of ED visits plausibly attributable to avoidance of cold exposure by individuals experiencing homelessness increased significantly in Ontario in 2022/2023, most notably in Toronto. This increase in ED visits may be related to inadequate access to emergency shelter beds and warming services in the community.

Nitrate ingestion blunts the increase in blood pressure during cool air exposure. A double-blind, placebo-controlled, randomized, crossover trial.

Cold exposure increases blood pressure (BP) and salivary flow rate (SFR). Increased cold-induced SFR would be hypothesised to enhance oral nitrate delivery for reduction to nitrite by oral anaerobes and to subsequently elevate plasma [nitrite] and nitric oxide bioavailability. We tested the hypothesis that dietary nitrate supplementation would increase plasma [nitrite] and lower BP to a greater extent in cool compared to normothermic conditions. Twelve males attended the laboratory on four occasions. Baseline measurements were completed at 28°C. Subsequently, participants ingested 140 mL of concentrated nitrate-rich (BR; ~13 mmol nitrate) or nitrate-depleted (PL) beetroot juice. Measurements were repeated over 3 h at either 28°C (Norm) or 20°C (Cool). Mean skin temperature was lowered compared to baseline in PL-Cool and BR-Cool. SFR was greater in BR-Norm, PL-Cool and BR-Cool than PL-Norm. Plasma [nitrite] at 3 h was higher in BR-Cool (592 ± 239 nM) vs. BR-Norm (410 ± 195 nM). Systolic BP (SBP) at 3 h was not different between PL-Norm (117 ± 6 mmHg) and BR-Norm (113 ± 9 mmHg). SBP increased above baseline at 1, 2 and 3 h in PL-Cool but not BR-Cool. These results suggest that BR consumption is more effective at increasing plasma [nitrite] in cool compared to normothermic conditions and blunts the rise in BP following acute cool air exposure, which might have implications for attenuating the increased cardiovascular strain in the cold.

Glycogen synthesis is required for adaptive thermogenesis in beige adipose tissue and affects diet-induced obesity.

Glycogen is a form of energy storage for glucose in different tissues such as liver and skeletal muscle. It remains incompletely understood how glycogen impacts on adipose tissue functionality. Cold exposure elevated the expression of Gys1 which encodes glycogen synthase 1 in brown adipose tissue (BAT) and inguinal white adipose tissue (iWAT). The in vivo function of Gys1 was analyzed using a mouse model in which Gys1 was deleted specifically in adipose tissues. Under normal chow conditions, Gys1 deletion caused little changes to body weight and glucose metabolism. Deletion of Gys1 abrogated upregulation of UCP1 and other thermogenesis-related genes in iWAT upon prolonged cold exposure or treatment with b3-adrenergic receptor agonist CL-316,243. Stimulation of UCP1 by CL-316,243 in adipose-derived stromal cells (SVFs) was also reduced by Gys1 deletion. Both the basal glycogen content and CL-316,243-stimulated glycogen accumulation in adipose tissues were reduced by Gys1 deletion. High-fat diet-induced obesity and insulin resistance were aggravated in Gys1-deleted mice. The loss of body weight upon CL-316,243 treatment was also abrogated by the loss of Gys1. In conclusion, our results underscore the pivotal role of glycogen synthesis in adaptive thermogenesis in beige adipose tissue and its impact on diet-induced obesity in mice.

Effect of Low Temperature on Content of Primary Metabolites in Two Wheat Genotypes Differing in Cold Tolerance

The study of cold-tolerance mechanisms of wheat as a leading cereal crop is very relevant to science. Primary metabolites play an important role in the formation of increased cold tolerance. The aim of this research is to define changes in the content of primary metabolites (soluble proteins and sugars), growth, and photosynthetic apparatus of freezing-tolerant and cold-sustainable wheat (Triticum aestivum L.) genotypes under optimal conditions and after prolonged (7 days) exposure to low temperature (4 °C). In order to gain a deeper comprehension of the mechanisms behind wheat genotypes’ adaptation to cold, we determined the expression levels of photosynthetic genes (RbcS, RbcL) and genes encoding cold-regulated proteins (Wcor726, CBF14). The results indicated different cold-adaptation strategies of freezing-tolerant and cold-sustainable wheat genotypes, with soluble proteins and sugars playing a significant role in this process. In plants of freezing-tolerant genotypes, the strategy of adaptation to low temperature was aimed at increasing the content of soluble proteins and modification of carbohydrate metabolism. The accumulation of sugars was not observed in wheat of cold-sustainable genotypes during chilling, but a high content of soluble proteins was maintained both under optimal conditions and after cold exposure. The adaptation strategies of wheat genotypes differing in cold tolerance were related to the expression of photosynthetic genes and genes encoding cold-regulated proteins. The data improve our knowledge of physiological and biochemical mechanisms of wheat cold adaptation.

Greenness, air pollution, and temperature exposure effects in predicting premature mortality and morbidity: A small-area study using spatial random forest model

BackgroundAlthough studies have provided negative impacts of air pollution, heat or cold exposure on mortality and morbidity, and positive effects of increased greenness on reducing them, a few studies have focused on exploring combined and synergetic effects of these exposures in predicting these health outcomes, and most had ignored the spatial autocorrelation in analyzing their health impact. This study aims to investigate the health impact of air pollution, greenness, and temperature exposure on premature mortality and morbidity within a spatial machine-learning modeling framework. MethodsYears of potential life lost reflecting premature mortality and comparative illness and disability ratio reflecting chronic morbidity from 1673 small areas covering Greater Manchester for the year 2008–2013 obtained. Average annual levels of NO2 concentration, normalized difference vegetation index (NDVI) representing greenness, and annual average air temperature were utilized to assess exposure in each area. These exposures were linked to health outcomes using non-spatial and spatial random forest (RF) models while accounting for spatial autocorrelation. ResultsSpatial-RF models provided the best predictive accuracy when accounted for spatial autocorrelation. Among the exposures considered, air pollution emerged as the most influential in predicting mortality and morbidity, followed by NDVI and temperature exposure. Nonlinear exposure-response relations were observed, and interactions between exposures illustrated specific ranges where combined effects either exacerbate or moderate health conditions. ConclusionAir pollution exposure had a greater negative impact on health compared to greenness and temperature exposure. Combined exposure effects may indicate the highest influence of premature mortality and morbidity burden.

Sleep and Thermoregulation in Birds: Cold Exposure Reduces Brain Temperature but Has Little Influence on Sleep Time and Sleep Architecture in Jackdaws (Coloeus monedula)

Birds have an electrophysiological sleep state that resembles mammalian rapid-eye-movement (REM) sleep. However, whether its regulation and function are similar is unclear. In the current experiment, we studied REM sleep regulation in jackdaws (Coloeus monedula) by exposing the birds to low ambient temperature, a procedure that selectively suppresses REM sleep in mammals. Eight jackdaws were equipped with electrodes to record brain activity and neck muscle activity and a thermistor to record cortical brain temperature. Recordings covered a three-day period starting with a 24 h baseline day at an ambient temperature of 21 °C, followed by a 12 h cold night at 4 °C, after which the ambient temperature was restored to 21 °C for the remaining recovery period. Cold exposure at night caused a significant drop in brain temperature of 1.4 °C compared to the baseline night. However, throughout the cold night, jackdaws expressed NREM sleep and REM sleep levels that were not significantly different from the baseline. Also, EEG spectral power during NREM sleep was unaffected by cold exposure. Thus, while cold exposure had a clear effect on brain temperature in jackdaws, it did not have the same REM sleep suppressing effect reported for mammals. These findings suggest that the REM-sleep-like state in birds, unlike REM sleep in mammals, is protected against the influence of low temperature.

Impaired autophagy following ex vivo cooling of simulated hypothermic temperatures in peripheral blood mononuclear cells from young and older adults

Hypothermia is a critical consequence of extreme cold exposure that increases the risk of cold-related injury and death in humans. While the initiation of cytoprotective mechanisms including the process of autophagy and the heat shock response (HSR) is crucial to cellular survival during periods of stress, age-related decrements in these systems may underlie cold-induced cellular vulnerability in older adults. Moreover, whether potential sex-related differences in autophagic regulation influence the human cold stress response remain unknown. We evaluated the effect of age and sex on mechanisms of cytoprotection (autophagy and the HSR) and cellular stress (apoptotic signaling and the acute inflammatory response) during ex vivo hypothermic cooling. Venous blood samples from 20 healthy young (10 females; mean [SD]: 22 [2] years) and 20 healthy older (10 females; 66 [5] years) adults were either isolated immediately (baseline) for peripheral blood mononuclear cells (PBMCs) or exposed to water bath temperatures maintained at 37, 35, 33, 31, or 4 °C for 90 min before PBMC isolation. Proteins associated with autophagy, apoptosis, the HSR, and inflammation were analyzed via Western blotting. Indicators of autophagic initiation and signaling (LC3, ULK1, and beclin-2) and the HSR (HSP90 and HSP70) increased when exposed to hypothermic temperatures in young and older adults (all p ≤ 0.007). Sex-related differences were only observed with autophagic initiation (ULK1; p = 0.015). However, despite increases in autophagic initiators ULK1 and beclin-2 (all p < 0.001), this was paralleled by autophagic dysfunction (increased p62) in all groups (all p < 0.001). Further, apoptotic (cleaved-caspase-3) and inflammatory (IL-6 and TNF-α) signaling increased in all groups (all p < 0.001). We demonstrated that exposure to hypothermic conditions is associated with autophagic dysfunction, irrespective of age or sex, although there may exist innate sex-related differences in cytoprotection in response to cold exposure as evidenced through altered autophagic initiation.

Ubiquitinome Analysis Uncovers Alterations in Synaptic Proteins and Glucose Metabolism Enzymes in the Hippocampi of Adolescent Mice Following Cold Exposure.

Cold exposure exerts negative effects on hippocampal nerve development in adolescent mice, but the underlying mechanisms are not fully understood. Given that ubiquitination is essential for neurodevelopmental processes, we attempted to investigate the effects of cold exposure on the hippocampus from the perspective of ubiquitination. By conducting a ubiquitinome analysis, we found that cold exposure caused changes in the ubiquitination levels of a variety of synaptic-associated proteins. We validated changes in postsynaptic density-95 (PSD-95) ubiquitination levels by immunoprecipitation, revealing reductions in both the K48 and K63 polyubiquitination levels of PSD-95. Golgi staining further demonstrated that cold exposure decreased the dendritic-spine density in the CA1 and CA3 regions of the hippocampus. Additionally, bioinformatics analysis revealed that differentially ubiquitinated proteins were enriched in the glycolytic, hypoxia-inducible factor-1 (HIF-1), and 5'-monophosphate (AMP)-activated protein kinase (AMPK) pathways. Protein expression analysis confirmed that cold exposure activated the mammalian target of rapamycin (mTOR)/HIF-1α pathway. We also observed suppression of pyruvate kinase M2 (PKM2) protein levels and the pyruvate kinase (PK) activity induced by cold exposure. Regarding oxidative phosphorylation, a dramatic decrease in mitochondrial respiratory-complex I activity was observed, along with reduced gene expression of the key subunits NADH: ubiquinone oxidoreductase core subunit V1 (Ndufv1) and Ndufv2. In summary, cold exposure negatively affects hippocampal neurodevelopment and causes abnormalities in energy homeostasis within the hippocampus.

Effect of chronic cold stress on gut microbial diversity, intestinal inflammation and pyroptosis in mice.

Hypothermia is an essential environmental factor in gastrointestinal diseases, but the main molecular mechanisms of pathogenesis remain unclear. The current study sought to better understand how chronic cold stress affects gut damage and its underlying mechanisms. In this work, to establish chronic cold stress (CS)-induced intestinal injury model, mice were subjected to continuous cold exposure (4°C) for 3h per day for 3weeks. Our results indicated that CS led to gut injury via inducing changes of heat shock proteins 70 (HSP70) and apoptosis-related (caspases-3, Bax and Bcl-2) proteins; enhancing expression of intestinal tight-related (ZO-1 and occludin) proteins; promoting releases of inducible nitric oxide synthase (iNOS), tumor necrosis factor-α (TNF-α), cyclooxygenase-2 (COX-2), high mobility group box 1 (HMGB1), interleukin1β (IL-1β), IL-18 and IL-6 inflammatory mediators in the ileum; and altering gut microbial diversity. Furthermore, persistent cold exposure resulted in the cleavage of pyroptosis-related Gasdermin D (GSDMD) protein by regulating the NLRP3/ASC/caspase-1 and caspase-11 pathway, and activation of toll-like receptor 4 (TLR4)/myeloid differentiation factor 88 (MyD88)-mediated nuclear factor kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways, which are strongly associated with changes in gut microbiota diversity. Taken together, these investigations provide new insights into the increased risk of intestinal disorders at extremely low temperatures and establish a theoretical foundation for the advancement of novel pharmaceutical interventions targeting cold-related ailments.

Experimental study on thermo-physiological differences between children and adults during indoor sedentary conditions

Previous research has shown that children prefer cooler environments and have lower thermal sensitivity than adults. This disparity may be attributed to physiological differences between these age groups. However, studies are scarce that specifically measure children's physiological parameters. In this study, we measured the physiological parameters of children aged 6–9 years and their parents, concurrently collecting their thermal comfort votes. Measured physiological parameters include metabolic rate, blood flow, body composition, core temperature, blood oxygen, heart rate, skinfold thickness, and skin temperature.We found that the average metabolic rate of the measured children was 1.20 met, 39% higher than the measured adults who had their average metabolic rate as 0.86 met. Children consistently exhibited higher metabolic rates than their own parents. Children were observed to have less body fat and thinner skin folds compared to adults. Additionally, children exhibited higher skin temperatures in core areas, elevated heart rates, and quicker recovery of skin blood flow and local skin temperature after experiencing cold exposure on hand compared to adults. These characteristics reveal children's superior thermoregulatory abilities, explaining their preference for cooler environments and reduced thermal sensitivity. Besides, no gender difference was observed in the thermal physiology of the measured children.All of the distinctive thermal physiological traits of children underscore the necessity of specific criteria for evaluating the thermal comfort of children.

Influence of shade and cold stratification on germination success of vegetative propagules from multiple Butomus umbellatus genotypes

Three experimental trials were conducted to investigate the influence of shade and cold stratification on germination success of vegetative propagules from multiple Butomus umbellatus genotypes. Shade level did not significantly impact germination of propagules in trial 1 (p=0.16); however, significant differences (p<0.0001) in germination percentages at the conclusion of the study were detected between genotypes. Rhizome segments of the triploid genotype one (G1) had the highest mean germination (95±1%); whereas bulbils of the diploid genotypes three (G3), four (G4), and five (G5) germinated to 9±2%, 1±1%, and 15±2%, respectively. Trial 2 focused on bulbils from G3, G4, and G5 diploid plants that were stratified at 4℃ for 35d. Like Trial 1, shade level was not significant (p=0.19) relative to the overall germination of cold-stratified bulbils. However, cold-stratified bulbils exhibited a much higher mean germination (≥93%) for all three genotypes. In Trial 3, the cold stratification treatments were significant and positively correlated to overall germination for G4 (p=0.005, r=0.77) and G5 (p=0.002, r=0.82), but not G3 (p=0.22, r=0.40) bulbils. Germination time significantly differed between genotypes in all cold-stratification treatments except for the 0, 120, and 180-day treatments. These studies demonstrate that a high percentage of vegetative propagules produced by B. umbellatus are capable of successfully germinating under laboratory conditions, but some require extended periods of cold exposure. Given that a single diploid bulbil can produce thousands of bulbils within a growing season; long term management of this species will need to be focused towards limiting bulbil production.

Geographic variation in larval cold tolerance and exposure across the invasion front of a widely established forest insect.

Under global climate change, high and low temperature extremes can drive shifts in species distributions. Across the range of a species, thermal tolerance is based on acclimatization, plasticity, and may undergo selection, shaping resilience to temperature stress. In this study, we measured variation in cold temperature tolerance of early instar larvae of an invasive forest insect, Lymantria dispar dispar L. (Lepidoptera: Erebidae), using populations sourced from a range of climates within the current introduced range in the Eastern United States. We tested for population differences in chill coma recovery (CCR) by measuring recovery time following a period of exposure to a nonlethal cold temperature in 2 cold exposure experiments. A 3rd experiment quantified growth responses after CCR to evaluate sublethal effects. Our results indicate that cold tolerance is linked to regional climate, with individuals from populations sourced from colder climates recovering faster from chill coma. While this geographic gradient is seen in many species, detecting this pattern is notable for an introduced species founded from a single point-source introduction. We demonstrate that the cold temperatures used in our experiments occur in nature during cold spells after spring egg hatch, but impacts to growth and survival appear low. We expect that population differences in cold temperature performance manifest more from differences in temperature-dependent growth than acute exposure. Evaluating intraspecific variation in cold tolerance increases our understanding of the role of climatic gradients on the physiology of an invasive species, and contributes to tools for predicting further expansion.