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At least 19 recordsLinked to original sources

PubMed2026

The effect of drysuit diving in warm water on body temperature and post immersion orthostatic hypotension.

INTRODUCTION: Warm-water diving can limit heat dissipation, particularly when performed in fully encapsulating protective gear, leading to substantial thermal and cardiovascular strain that may impair diver safety. Following immersion, removal of hydrostatic support combined with heat-induced vasodilation may reduce central blood volume and increase susceptibility to orthostatic intolerance during egress and recovery. The extent to which this thermal strain impairs post-immersion orthostatic tolerance remains unknown. METHODS: Four randomised, crossover immersion trials were conducted at 28°C, 33°C, 38°C without precooling (38°C), and 38°C with precooling (38°C + Cool), with subjects wearing fully encapsulating dive gear. Subjects walked for up to 60 minutes at approximately 50% of O2max heart rate (HR) or until core temperature (Tc) reached 38.5°C, or they voluntarily stopped. Tc, HR, and perceptual measures were recorded every 10 minutes. Orthostatic tolerance was assessed after immersion via a 70° head-up tilt test. RESULTS: Eight healthy adults completed all aspects of the study. Tc and HR were higher during both 38°C conditions compared with 28°C and 33°C (all P < 0.01) with no differences between 38°C and 38°C + Cool. Sweat loss exceeded 1.2 (SD 0.67) L⋅h-1 in both 38°C conditions compared with ≤ 0.3 (0.32) L⋅h-1 at 28°C and 33°C (P < 0.01). Survival analysis showed orthostatic tolerance decreased with increasing thermal stress (log-rank P = 0.027; trend P = 0.003). Precooling did not reduce peak Tc or HR, nor did it improve tolerance time in 38°C water. CONCLUSIONS: Encapsulated warm-water diving causes heat stress and cardiovascular strain that persists after immersion, impairing orthostatic tolerance. Precooling does not significantly reduce these outcomes.

Humans↗

PubMed2026

Impact of a thermal care bundle on peri-operative hypothermia, surgical site infection, and readmissions in osteosynthesis patients: A randomised controlled trial.

BACKGROUND: Maintaining normothermia throughout the peri-operative period prevents the occurrence of complications related to hypothermia. OBJECTIVE: To determine the effect of a thermal care bundle with a short prewarming period on inadvertent peri-operative hypothermia (IPH), surgical site infection (SSI), and unplanned readmission among osteosynthesis patients, and to identify associated variables. DESIGN: Open-label, randomised controlled trial. SETTING: University hospital. PATIENTS: One hundred and forty-eight patients who underwent osteosynthesis surgery. INTERVENTION: The intervention group received the thermal care bundle, which consisted in prewarming patients 10 min before anaesthesia delivery and maintaining body temperature with a forced air device during surgery and the immediate postoperative period; in addition, the operating room environmental temperature was kept at 21 °C, and fluids were warmed to 38 °C. MAIN OUTCOME MEASURES: For the primary objective, hypothermia was defined as core body temperature below 36 °C and measured using the 3M Spot On zero heat flux sensor. Core temperature was recorded upon admission to the pre-operative holding area and subsequently every 30 min until postanaesthesia care unit (PACU) discharge. Secondary objectives were SSI and readmissions: a follow-up at 30 to 60 and 90 days was performed by the principal investigator. RESULTS: All 148 patients completed the study, and there were no significant differences between the groups at baseline. At the start of surgery, the incidence of hypothermia was significantly lower in the bundle group (1.3 vs. 9.9% among controls; odds ratio = 7.59, P  = 0.021). A significantly lower incidence of hypothermia was also observed at admission to the PACU (14.3% in the bundle group vs. 29.6% among controls; odds ratio = 2.07; P  = 0.024). Application of the bundle increased patients' core body temperature by 0.13 °C (95% confidence interval (CI), 0.003 to 0.254; P  = 0.045). Patients in the bundle group had a slightly lower observed incidence of wound infections requiring readmission (odds ratio = 0.35; 95% CI, 0.04 to 2.92), although this difference was not statistically significant ( P  = 0.332). CONCLUSIONS: The bundle reduces peri-operative hypothermia by up to 59%, but does not affect on SSI; factors like presurgery hospital stay, operating room and PACU occupancy were identified as risk factors for SSI. REGISTRATION: 21 July 2022: NCT05469958 (Clinical Trials.gov), first recruitment 15 August 2022.

Adult↗

PubMed2026

Effect of Local Anesthetic Solution at Different Temperatures for Epidural Labor Analgesia on Intrapartum Fever: A Randomized Clinical Trial.

BACKGROUND: Whether heating local anesthetic solutions to core body temperature (37°C) for epidural labor analgesia reduces intrapartum fever incidence remains undefined in the current literature. METHODS: This double-blind randomized controlled trial (RCT) enrolled 220 nulliparous parturients (18-35 years, American Society of Anesthesiologists [ASA] physical status II, term singleton pregnancy). Participants were randomized to receive epidural labor analgesia with 0.075% ropivacaine + 0.5 µg/mL sufentanil at 37°C (warmed group) or 22°C (room-temperature group). Epidurals were placed at L3-L4 with a test dose of 3 mL of 1.5% lidocaine at room temperature, followed by programmed bolus epidural analgesia (initial 10 mL, 10 mL/h) and patient-controlled epidural analgesia (PCEA) 5 mL (30-minute lockout). Tympanic temperature was measured every 30 minutes from epidural initiation to delivery, defining intrapartum fever as ≥38°C. The primary outcome was fever incidence, on which the power analysis was based, and also maximum temperature and shivering. Secondary outcomes comprised analgesia onset, block level, labor durations, neonatal Apgar scores, umbilical cord blood pH and BE, and maternal adverse events. RESULTS: A total of 220 parturients were included (warmed group, n = 110; room-temperature group, n = 110). The warmed group had a lower intrapartum fever incidence (15.5% [17/110] vs 30.9% [34/110], relative risk [RR] 0.5 [95% confidence interval {CI}, 0.298-0.840]; P = .007); however, the reduction of 49.8% did not reach the preset clinically meaningful difference of 60% reduction proposed in the power analysis. The maximum body temperature was also lower in the warmed group: median (interquartile range [IQR]) 37.4 (IQR, 37.2-37.7) °C vs 37.6 (IQR, 37.3-38.0) °C, median difference -0.2 (95% CI, -0.3 to -0.1) °C ( P = .006). Shivering incidence was not different between groups (10.9% [12/110] vs 14.5% [16/110]; P = .418). No statistically significant differences were observed between groups in any of the secondary outcomes assessed, including block characteristics, local anesthetic consumption, labor duration, neonatal outcomes, and maternal adverse events. CONCLUSION: Although we found a 50% reduction in the incidence of temperature rise using warmed (37°C) local anesthetics for epidural labor analgesia, this did not reach our preset threshold of 60% reduction.

Humans↗

PubMed2026

Integrated transcriptomic analysis of mRNA and miRNA in Brown adipose tissue of the greater horseshoe bats during hibernation.

Hibernation enables animals survive harsh environments by conserving energy through reduced metabolism and body temperature. Brown adipose tissue (BAT) plays a critical role in non-shivering thermogenesis, crucial for warming up during arousal phase. The greater horseshoe bats (Rhinolophus nippon) are typical hibernators and non-shivering thermogenesis in BAT tissue may persist throughout the arousal process in bats. This study examines gene expression and regulatory changes in BAT of these bats across active, hibernation, and arousal phases using transcriptome and miRNA sequencing. A total of 2721 differentially expressed mRNAs and 268 differentially expressed miRNAs were identified. The results reveal that the BAT transcriptome undergoes state-dependent remodeling throughout the hibernation process. The most pronounced divergence occurs between the active phase and torpor, involving cell cycle arrest, immunosuppression, thermogenic signal desensitization, and upregulation of lipid metabolism and autophagy pathways, reflecting the coordinated adaptation of energy conservation and thermogenic reserve. In contrast, transcriptional alterations between torpor and arousal are extremely limited, indicating that torpid BAT is already pre-primed for thermogenesis and requires only modest transcriptional adjustments to activate heat production. Notably, although body temperature recovers to active-phase levels during arousal, the molecular signature of BAT remains highly similar to that of the torpid state. Furthermore, the core thermogenic gene UCP1 showed no significant expression differences across the three groups. In conclusion, this study systematically delineates the miRNA-mRNA regulatory landscape of bat BAT across the hibernation process, and deepens our understanding of the thermoregulatory mechanisms underlying mammalian hibernation.

BAT↗

PubMed2026

Thermal biology characteristics of the Caspian whipsnake (Dolichophis caspius, Gmelin, 1789) under natural and laboratory conditions.

Reptiles rely on behavioural thermoregulation to maintain optimal body temperature (Tb), essential for many physiological functions. However, thermal biology remains poorly studied in many snake species, including the Caspian whipsnake (Dolichophis caspius, Gmelin, 1789). This study examined the thermal biology of the Caspian whipsnake under natural and laboratory conditions. In the field, we investigated the influence of sex, age category, season, time of day, air temperature, detection status, feeding status, and shedding phase on Tb. Under controlled conditions, we assessed preferred Tb variation and its relationship to active thermoregulation. In the field, Tb was significantly affected by sex, season, time of day, air temperature, feeding status, and shedding phase, but not age category, body size or detection status. Males had lower Tb than females and snakes with food in their stomachs exhibited higher Tb. Tb increased from March to June and from morning to afternoon, and air temperature had a positive effect on Tb. In the laboratory, mean Tb (24.5 ± 4.9 °C) was lower than in the field (26.9 ± 5.2 °C) and was significantly associated with body posture and terrarium part, indicating active behavioural thermoregulation. In the laboratory, males had lower Tb than females, and juveniles had lower Tb than adults. The lower thermal preference suggests a cooler thermal niche than many colubrids, potentially increasing their susceptibility to climate warming. However, the broad Tb variation and behavioural thermoregulation indicate some flexibility in responding to environmental changes. These findings highlight the role of behavioural thermoregulation in snake thermal responses to environmental variation.

Behavioural thermoregulation↗

PubMed2026

Impact of kangaroo care on circadian rhythm, growth, physiological stability in premature infants, and cortisol and melatonin levels in maternal breast milk: A randomized controlled trial.

PURPOSE: This study aimed to examine the effects of regular kangaroo care (KC) on sleep-wake cycles, growth, physiological stability, and maternal breast milk cortisol and melatonin levels in premature infants. DESIGN: This study was a parallel group, single-blind, pre-test-post-test, randomised controlled trial (RCT). METHODS: This randomized controlled study was conducted in a neonatal intensive care unit (NICU) in Türkiye between September 2024 and September 2025 Thirty-six premature infants were randomized to intervention (n = 28) or control (n = 28). Infants in the intervention group received KC for three consecutive days, twice daily (10:00 a.m. and 10:00 p.m.) for 60 min per session. Data were collected using the Infant Information Form, Physiological Parameters Monitoring Chart, and Premature Infant Sleep-Wake Cycles Tracking Chart. Sleep-wake cycles were monitored using a Bispectral Index device. Breast milk cortisol and melatonin levels were measured at baseline and on day three using the competitive ELISA method. The study was registered at ClinicalTrials.gov (NCT06589349). RESULTS: Regular KC had a statistically significant effect on BIS values, heart rate, respiratory rate, oxygen saturation, and body temperature (p < 0.05). No statistically significant effects were observed on infant body weight or on maternal breast milk cortisol and melatonin levels (p > 0.05). CONCLUSION: The findings indicate that regular KC is associated with improved regulation of the sleep-wake cycle and enhanced physiological stability in premature infants. No significant changes were observed in maternal breast milk cortisol or melatonin levels following KC.

Humans↗

PubMed2025

Expansion of the functional genomics GRACE library reveals genes relevant for temperature-dependent fitness in Candida albicans.

A small percentage of species in the fungal kingdom can cause devastating infections in humans, with Candida albicans reigning as a leading cause of systemic disease. One of the key virulence phenotypes for pathogenic fungi is the ability to survive at host body temperature; however, a comprehensive understanding of the mechanisms that orchestrate thermal adaptation in fungi remains incomplete. In this study, we expand the largest functional genomics resource in C. albicans, reaching 71.3% coverage of the entire genome, and perform screens under six different temperatures to identify genes important for temperature-dependent fitness. We describe the function of genes involved in translation (GAR1), splicing (C1_11680C or YSF3), and cell cycle progression (C6_00110C or RHT1) in enabling fungal survival at both low and high temperatures. Through experimental evolution, we also show that C. albicans can rapidly overcome deleterious mutations and adapt to extreme temperature environments. Overall, our study highlights the transformative potential of genome-wide functional genomics to uncover critical vulnerabilities in pathogenic fungi.

Genomics↗

PubMed2026

Assessing the genetic potential of a milk mid-infrared prediction of heat stress response in dairy cows using a temperature-humidity index-independent approach.

Selection for heat tolerance remains challenging due to the difficulty of accessing reliable phenotypes at large scale. An alternative could be established using mid-infrared spectra, which are collected routinely through milk recording, and have already shown their value as proxies for a variety of phenotypes that are costly or difficult to measure. Recently, a first prediction of heat stress response in dairy cows based solely on milk mid-infrared spectra was developed. This prediction was obtained using models calibrated on surface body temperature and milk composition variations. Its potential as a detection tool was explored, but no genetic analyses has been performed. On this basis, the objectives of this study were to estimate the heritability of the predicted heat stress response, assess its genetic correlations with traits from the Walloon official genetic evaluation, and identify genomic regions associated with heat tolerance through a GWAS, all without using temperature-humidity index (THI) information. The estimated heritability (0.10) was low but sufficient to enable genetic selection and consistent with expectations for a heat stress-related trait. Also as expected, an antagonistic relationship between heat tolerance and milk production was observed, but its extent was notably reduced compared with traditional approaches. In addition, genetic correlations with other traits were neutral (fat yield) or favorable (protein yield, SCS, fertility, longevity). Concerning the GWAS, genomic regions and candidate genes previously associated with the response to heat stress were highlighted, as well as others related to energy balance maintenance. Overall, these results support the relevance of the prediction for the heat stress response as a new phenotype for heat tolerance selection that does not require any THI information. They also reinforce the importance of energy balance for dairy cows to cope with heat stress.

Journal Article↗

PubMed2026

Pre-clinical immunogenicity and safety evaluation of H2 strain Hepatitis A Inactivated Vaccine in rhesus macaques.

BACKGROUND: Hepatitis A is a viral infection of the liver that can cause mild to severe illness. Currently, two types of HAV vaccines are used worldwide, inactivated hepatitis A vaccines, which are used in most countries, and live attenuated vaccines (H2 and L-A-1 strain), which are mainly used in China. The major disadvantage of live attenuated virus to cause secondary infections among contacts and mutation shifts of the live vaccine strain. The H2 strain was selected for the development of an inactivated hepatitis A vaccine to further reduce biosafety risks. Rhesus macaques high genomic homology with humans and the incubation period after hepatitis A vaccination and human natural infections are similar. We use rhesus macaques to assess immunogenicity and safety of the H2 strain Hepatitis A Inactivated Vaccine. METHODS: The vaccine was assessed in rhesus macaques, divided into four groups (n = 10 per group): the control group (adjuvant buffer; aluminum content 0.35 mg/mL; 2 mL per dose), the low-dose group (320EU, 0.5 mL of 640EU/mL with aluminum content 0.35 mg/mL), the medium-dose group (640EU, 1 mL of 640EU/mL with aluminum content 0.35 mg/mL), and the high-dose group (1280EU, 2 mL of 640EU/mL with aluminum content 0.35 mg/mL). Animals were injected intramuscularly at multiple sites in the hind limbs and received four inoculations at 4-week intervals. Test items including Clinical indicators, immunogenicity indicators and Histopathological examination. RESULTS: No abnormalities were observed in any group in terms of general clinical condition throughout the study period except for slight decreases in body temperature after immunization. Hematological parameters, serum biochemistry indices, and histopathological findings showed fluctuated to different degrees of fluctuation after immunization across all groups. Immunogenicity assessments showed that the inactivated hepatitis A vaccine (H2) induced both humoral and cellular immune responses effectively, and the levels of antibodies increased with certain dose- and time-response trends. CONCLUSION: The inactivated hepatitis A vaccine (H2 strain, human diploid cell) was safe and immunogenic in non-human primates. The results provide strong preclinical support for the further clinical development of this vaccine candidate.

Animals↗

PubMed2025

Population pharmacokinetics and dosing optimization of cefoselis in paediatric patients with haematological malignancies.

BACKGROUND: Cefoselis is a fourth-generation cephalosporin primarily indicated for infections caused by susceptible bacteria. The pharmacokinetic (PK) characteristics, efficacy and safety of cefoselis in paediatric patients with haematological malignancies remain unclear, posing a risk of suboptimal exposure and associated therapeutic failure or toxicity. Therefore, we studied cefoselis pharmacokinetics (PK) to optimize dosing in paediatric patients with haematological malignancies. METHODS: Blood samples were collected from paediatric patients with haematological malignancies. A population PK (PopPK) analysis was performed using NONMEM (v7.4). Monte Carlo simulations were used to evaluate current dosing regimens by calculating the PTA. Pharmacodynamic target was defined as unbound plasma concentrations above the MIC throughout the entire dosing interval. Clinical efficacy and safety data were collected. RESULTS: A total of 96 samples from 53 patients were collected. A two-compartment model with zero-order input and first-order elimination best described the PK of cefoselis after IV administration. Weight was the only covariate that affected PK. Monte Carlo simulations showed that the PTA was more than 96.7% for susceptible pathogens (MIC = 0.25 mg/L) at 40 mg/kg, and less than 30.5% for Pseudomonas aeruginosa (MIC = 32 mg/L) at 80 mg/kg. A total of 39 patients had body temperatures below 37.3°C after 3 ± 1 days of cefoselis treatment (with a median baseline temperature of 38.5°C). There were no adverse events leading to discontinuation. CONCLUSIONS: A PopPK model of cefoselis in paediatric patients with haematological malignancies was established and the dosing regimens were evaluated.

Humans↗

PubMed2026

Genotype II Live-Attenuated ASFV Vaccine Bearing 24 Genes Deletion in 3 Independent Regions Is Able to Provide Complete Protection Against Homologous Lethal Challenge.

African swine fever (ASF) is an acute, febrile, and highly contagious infectious disease of swine with the etiological agent of African swine fever virus (ASFV). The mortality rate of virulent strains is as high as 100%. Strengthening biosafety is so far the most effective way to prevent and control ASF. Therefore, it is urgent to develop a safe and effective vaccine. In this study, a Genotype II live-attenuated ASF vaccine bearing 24 genes deletion in 3 independent regions was constructed based on the highly virulent Eurasian strain ASFV CN/GS 2018 backbone. The resulting mutant ASFV-Δ24 is characterized by complete deletion of 24 genes distributed in 3 genomic positions of 852 to 11 468, 19 732 to 22 929, and 179 519 to 180 617, among which MGF100 and whole MGF300 families are pioneeringly removed. The ASFV-Δ24 displayed a delayed and reduced replication kinetics as well as aberrant icosahedral empty particles devoid of a nucleoid when compared to the parental virus. Animal experiments showed that ASFV-Δ24 was completely attenuated in animals as evidenced by stable body temperature and no ASF-compatible clinical signs in vaccinated pigs. The ASFV-Δ24 could provide complete homologous protection against lethal challenge, as vaccinated pigs demonstrated boosted antibody response, transient but low levels of viremia in blood and virus titers in organs as well as almost undetectable viral shedding. Gene deletions in multiple regions are helpful for prevention of virulence reversion. These results indicate that ASFV-Δ24 can be used as an effective and promising candidate vaccine to control the spread of ASFV.

Animals↗

PubMed2026

[Mechanism of Tianshu Capsules in treating migraine rats based on gut microbiota].

This study aims to investigate the therapeutic effect of Tianshu Capsules(TS) on migraine rat model and explore its potential mechanism of action from the perspectives of the structure of the gut microbiota and functional pathway regulation. A migraine rat model was established via subcutaneous injection of nitroglycerin. The Sprague-Dawley rats were randomly divided into a control group, a model group, a low-dose TS group, a medium-dose TS group, a high-dose TS group, and an ibuprofen group. The efficacy of TS in improving migraine was evaluated by general condition observation and measurement of the craniofacial pain threshold. The expression of the gene c-fos in the trigeminal ganglion was determined by quantitative real-time polymerase chain reaction(PCR). The contents of endothelin-1(ET-1), calcitonin gene-related peptide(CGRP), and 5-hydroxytryptamine(5-HT) in serum were measured by enzyme-linked immunosorbent assay(ELISA). Fecal samples were subjected to metagenomic sequencing for systematic analysis of gut microbial diversity, taxonomic composition difference, and functional pathway changes of Kyoto Encyclopedia of Genes and Genomes(KEGG), and their correlations with behavioral and biochemical indices were further evaluated. The results show that TS significantly improves the increased body temperature and decreased craniofacial pain threshold in migraine rats. It also markedly suppresses the elevated expression levels of the gene c-fos in the trigeminal ganglion and reduces the levels of ET-1, CGRP, and 5-HT in serum. Metagenomic beta diversity analysis and differential taxonomic abundance analysis reveal that the migraine model induces significant gut microbiota dysbiosis, characterized by enrichment of harmful genera, including Streptococcus and Enterococcus, as well as a decline in the abundance of beneficial bacteria such as Allobaculum, Eubacterium, and Muribaculum. Functional pathway analysis results of KEGG further reveal that the relative abundances of pathways associated with biosynthesis of phenylalanine, tyrosine, and tryptophan, bacterial secretion system, citrate cycle, and biosynthesis of secondary metabolites are significantly decreased in the model group. TS intervention increased the abundance of the genus, such as Parabacteroides, Eubacterium, Allobaculum, and Muribaculum, while decreasing levels of microbiota, including Staphylococcus. TS also significantly upregulated pathways associated with barrier function(tight junction), amino acid biosynthesis pathways, and biosynthesis pathways of neurotransmitter precursors such as cysteine and methionine metabolism. In addition, it downregulated inflammatory pathways(Toll and IMD signaling) and pathways related to Staphylococcus aureus infection, thereby restoring the structure and function of the microbiota to a state close to those of the normal group. Spearman correlation analysis reveals that partial gut microbiota are significantly associated with migraine-related behavioral and biochemical indices(c-fos, ET-1, CGRP, and 5-HT). In conclusion, TS can regulate the disrupted gut microbiota structure and microbial functions related to neurotransmitter metabolism, intestinal barrier function, and inflammatory regulation in migraine model rats, which may be one of the potential key ways through which TS exert its anti-migraine effect.

Animals↗

PubMed2026

Potential Links Between Physiological and Perceptual Strain in High Heat Stress.

The physiological strain index (PhSI) is widely used to quantify thermoregulatory and cardiovascular strain during heat stress. However, direct physiological measurements may not always be feasible in occupational or athletic settings. Therefore, this study aimed to examine the relationship and agreement between perceptual strain and integrated physiological strain indices during high heat stress. Ten healthy, physically active, non-heat-acclimated males (29 (7) yr; 1.79 (0.11) m; 77.4 (9.3) kg) completed two randomized crossover exercise trials in hot-dry (HD) and warm-humid (WH) environments with equivalent wet-bulb globe temperatures. Heart rate, rectal temperature, skin temperature, rating of perceived exertion, and thermal sensation were measured at baseline and every 15 minutes during 60 minutes of cycling. Physiological strain index (PhSI), adaptive physiological strain index (aPhSI), and perceptual strain index (PeSI) were calculated using validated equations. Repeated-measures correlation analyses demonstrated very strong associations between PeSI and both PhSI and aPhSI under HD (Rrm = 0.940-0.943) and WH (Rrm = 0.980-0.982; all p < 0.001). Receiver operating characteristic analyses demonstrated good-to-excellent discrimination of physiological strain by PeSI (AUC = 0.895-0.969). Mixed-effects analyses showed that higher PeSI values were associated with increased PhSI (β = 1.325, p < 0.001) and aPhSI (β = 1.459, p < 0.001). However, Bland-Altman analyses demonstrated relatively small mean biases (0.4-0.9 AU) but wide limits of agreement (-2.8 to 4.2 AU), indicating that PeSI and physiological strain indices are not interchangeable. These findings suggest that PeSI may serve as a practical adjunctive or screening indicator of physiological strain when direct physiological measurements are unavailable.

Humans↗

PubMed2026

Non-linear predictive modeling and comprehensive meta-analysis of rectal temperature in Santa Inês sheep: a systematic review of thermal challenges and biometerological trends.

A systematic and bibliometric review, combined with a meta-analysis, was used to adjust an equation for estimating the physiological responses of Santa Inês sheep subjected to different thermal challenges. The systematic review compiled data on physiological responses and the thermal environment, which were then used in the meta-analysis to adjust regression models. The bibliometric analysis mapped the relationships among studies, highlighting their usefulness in interpreting research findings and biases. Addressing prior methodological critiques, the core of this study involves replacing the linear approach with a non-linear segmented regression model to accurately define the Thermal Neutral Zone (TNZ). The Segmented Regression Model was crucial, establishing the upper limit of the Thermal Neutral Zone (TNZ) at an air temperature (tair) of 34.64 °C, where trectal begins to increase abruptly. The model, while identifying a biologically significant breakpoint, exhibited a moderate Multiple R-squared of 0.3529, highlighting the high heterogeneity and methodological variability in the current Santa Inês literature. This non-linear approach offers a biologically superior tool for identifying the onset of thermal distress.

Animals↗

PubMed2024

Cooling lactating sows exposed to early summer heat wave alters circadian patterns of behavior and rhythms of respiration, rectal temperature, and saliva melatonin.

Heat stress (HS) exerts detrimental effects on animal production, with lactating sows being particularly vulnerable. Understanding the mechanisms involved in HS response could aid in developing effective strategies against the negative impacts on livestock. Recent genome wide association studies identified two core circadian clock genes as potential candidates in mediating HS response. The study aimed to investigate how cooling lactating sows under natural heat stress conditions impacted circadian patterns of respiration rate (RR), rectal temperature (RT), behavior, salivary melatonin and cortisol levels, and diurnal patterns of cytokines in saliva. Mixed parity lactating sows were assigned to one of two treatment groups: electronic cooling pad (C; n = 9) and heat-stressed (H; n = 9). The experiment spanned two 48 h periods of elevated ambient temperatures due to summer heat wave. In the first 48 h period, RR was recorded every 30 min, RT every 60 min, and behaviors (eating, standing, sitting, laying, sleeping, drinking, and nursing) every 5 min. In the second 48 h period, saliva samples were collected every 4 h. Cooling reduced RR and RT and altered circadian patterns (P < 0.05). Cooling did not affect amount of time engaged in any behavior over the 48 h period (P > 0.05), however, daily patterns of eating, standing and laying differed between the treatments (P < 0.05), with altered eating behavior related to RT increment in H sows (P < 0.05). Cooling increased and altered the circadian pattern of salivary melatonin (P < 0.05). Cooling also influenced the diurnal pattern of saliva cytokines. Cooling had no impact on saliva cortisol levels. In conclusion, cooling HS sows impacted circadian rhythms of physiology and behavior, supporting the need for further research to understand if circadian disruption underlies decreased production efficiency of HS animals.

Animals↗

PubMed2026

Quantifying the evolutionary potential for Delta Smelt persistence in a warming habitat.

Long-term persistence of managed species will depend, in part, on whether the species harbors the physiological or genetic potential to adjust to warming temperatures, and whether relevant genetic variation is modified by management practices. The critically endangered Delta Smelt (Hypomesus transpacificus) is intensively managed, but little is known about the presence of genetic variation for resistance to elevated temperature, which will be important to maintain for their persistence in a rapidly warming future. Using a pedigree and whole genome sequencing data, we characterized the genetic variation and genomic architecture for CTMax (as a metric of upper thermal tolerance) across control and elevated rearing temperatures, alongside covarying traits (body size, degree of hatchery ancestry). Warmer rearing temperatures increased CTMax through acclimation but also resulted in reduced additive genetic variation for the trait, which could constrain adaptation under thermal stress. We found that larger fish had reduced CTMax, although this effect was diminished at elevated temperatures. We observed modest heritability for CTMax at rearing temperatures of 15°C and 18°C (0.26 and 0.16, respectively), but only a limited number of loci were identified that had consistent effects on CTMax across rearing temperatures. Instead, the genomic basis of thermal tolerance was highly dependent on rearing temperature (many loci detected with a GxE effect). The influence of domestication selection was indicated by changes in allele frequency, and divergence in upper thermal tolerance and plasticity, between low and high hatchery ancestry groups. Minimal overlap between loci associated with domestication and CTMax suggests that these traits possess separate genetic underpinnings. Knowledge of genetic variation supporting ecologically relevant physiological variation may be useful for refuge management and may inform supplementation in an ever-warming environment.

conservation physiology↗

PubMed2026

Quantifying the Evolutionary Potential for Delta Smelt Persistence in a Warming Habitat.

Long-term persistence of managed species will depend, in part, on whether the species harbors the physiological or genetic potential to adjust to warming temperatures, and whether relevant genetic variation is modified by management practices. The critically endangered Delta Smelt (Hypomesus transpacificus) is intensively managed, but little is known about the presence of genetic variation for resistance to elevated temperature. Using a pedigree and whole genome sequencing data, we characterized the genetic basis of CTMax (as a metric of upper thermal tolerance) across control and elevated rearing temperatures, alongside covarying traits (body size and degree of hatchery ancestry). Warmer rearing temperatures increased CTMax through acclimation but also resulted in reduced additive genetic variation for the trait. We observed modest heritability for CTMax at rearing temperatures of 15°C and 18°C (0.26 and 0.16, respectively), but only a limited number of loci were identified that had consistent effects on CTMax across rearing temperatures. Instead, the genomic basis of thermal tolerance was highly dependent on rearing temperature (i.e., many loci detected with a GxE effect). This temperature-dependent genomic architecture is consistent with our finding that additive genetic variation for CTMax was reduced under warmer rearing conditions, indicating a potential constraint on adaptive evolutionary change. The influence of domestication selection was indicated by changes in allele frequency, and divergence in upper thermal tolerance and plasticity, between low and high hatchery ancestry groups. Minimal overlap between loci associated with domestication and CTMax suggests that these traits possess separate genetic underpinnings. Knowledge of genetic variation supporting ecologically relevant physiological variation may be useful for captive management and may inform supplementation of fish to the wild in an ever-warming environment.

conservation physiology↗

PubMed2025

Expression of De Novo Open Reading Frames in Natural Populations of Drosophila melanogaster.

De novo genes, which originate from noncoding DNA, are known to have a high rate of turnover over short evolutionary timescales, such as within a species. Thus, their expression is often lineage- or genetic background-specific. However, little is known about their levels and breadth of expression as populations of a species diverge. In this study, we utilized publicly available RNA-seq data to examine the expression of newly evolved open reading frames (neORFs) in comparison to non- and protein-coding genes in Drosophila melanogaster populations from the derived species range in Europe and the ancestral range in sub-Saharan Africa. Our datasets included two adult tissue types as well as whole bodies at two temperatures for both sexes and three larval/prepupal developmental stages in a single tissue and sex, which allowed us to examine neORF expression and divergence across multiple sample types as well as sex and population. We detected a relatively large proportion (approximately 50%) of annotated neORFs as expressed in the population samples, with neORFs often showing greater expression divergence between populations than non- or protein-coding genes. However, differential expression of neORFs between populations tended to occur in a sample type-specific manner. On the other hand, neORFs displayed less sex-biased expression than the other two gene classes, with the majority of sex-biased neORFs detected in whole bodies, which may be attributable to the presence of the gonads. We also found that neORFs shared among multiple lines in the original set of inbred lines in which they were first detected were more likely to be both expressed and differentially expressed in the new population samples, suggesting that neORFs at a higher frequency (i.e. present in more individuals) within a species are more likely to be functional.

Animals↗