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At least 19 recordsLinked to original sources
PubMed2026

Transcriptomic insights into thermal stress reveal physiological trade-off between thermal stress adaptation and reproductive investment in Spodoptera litura.

Spodoptera litura, a highly polyphagous lepidopteran pest, poses a major threat to agricultural productivity due to its remarkable adaptability to diverse environmental conditions. Although heat stress is known to trigger transcriptional reprogramming in insects, the molecular mechanisms underlying thermal stress responses in S. litura remain poorly understood. In the present study, fourth-instar larvae were exposed to acute heat stress (44 °C) and compared with control conditions (27 ± 1 °C) to investigate heat-induced transcriptional alterations affecting physiology and reproduction. High-quality RNA-Seq data achieved more than 80% mapping efficiency, with a total of 15,782 transcripts were identified. Transcriptome analysis of S. litura larvae showed 323 differentially expressed genes (DEGs), of which 262 genes were significantly upregulated and 61 were downregulated in heat-stressed larvae compared to the control group. The DEGs were associated with stress response, reproduction, signalling, proteostasis, detoxification, oxidative stress, metabolism, development, and chromatin regulation. Heat shock proteins genes, including HSP70, HSP90, and HSP27, together with co-chaperones such as TRET-1, STIP1, and Starvin, were strongly upregulated, indicating enhanced cellular protection against protein damage and oxidative stress under heat stress. Conversely, key reproductive and cell cycle-related genes, including BARR, CAPD2, FEO, CDK2 and MORULA, were significantly downregulated, suggesting reproductive impairment and developmental arrest. RT-qPCR validation corroborated the RNA-Seq findings, demonstrating a heat-induced physiological trade-off that prioritizes survival over reproduction. Consistent with these molecular responses, heat-stressed insects exhibited marked reproductive impairment, including significant reductions in gonadosomatic index, eupyrene sperm bundle count, mating frequency, mating success, female calling behaviour, copulation duration, fecundity, and egg fertility. Collectively, these findings provide comprehensive insights into the molecular basis of thermal adaptation in S. litura and demonstrate that acute heat stress compromises reproductive fitness while activating conserved stress-response pathways that promote short-term survival.

Animals↗
PubMed1979

Cockpit thermal stress and aircrew thermal strain during routine Jaguar operations.

Thermal data have been obtained from Jaguar aircraft flying routine, warm-weather operations in Sardinia. These data have been analysed in terms of the ambient and cockpit wet bulb globe temperatures (WBGT) and the mean body temperature (Tb) of the pilot. In contrast to similar data previously obtained from Harrier and Buccaneer aircraft, no interrelationships could be demonstrated between ambient WBGT at ground level and either cockpit WBGT or pilot Tb. Relationships which could be described by equations of negative slope were obtained between Tb and sortie time and between cockpit WBGT and sortie time. A model has been derived for predicting aircrew thermal strain in the Jaguar from cockpit temperature and sortie time.

Aerospace Medicine↗
PubMed1979

[5-Hydroxyindoleacetic acid and creatinine excretion in thermal stress].

The determination of 5-HIIA and creatinine excretion in thermal stress was performed in two series, in the first (I) on 102 healthy men aged 20--45 yrs (58 smokers and 55 non-smokers) and in the second one (II) on 20 men after drinking of 1 1 water immediately before thermal stress. The subjects remained at rest in the climatic chamber for 90 min in the temperature of 45 +/- 1 degrees C and relative humidity of 70 +/- 5 per cent. Thermal stress resulted in a significant increment of body temperature after 45 min and after consecutive 45 min of exposure, and lack of steady state. Creatinine and 5-HIIA were determined in two urine portions after 45 and after consecutive 45 min of exposure. Total amounts of excreted 5-HIIA and creatinine in the first urine portion in (I) and (II) were significantly higher in comparison with normal values; they did not depend on the amount of urine voided. The 5-HIIA excretion was significantly higher in smokers after the first 45 min of exposure only. Total amounts of excreted 5-HIIA and creatinine after another 45 min of exposure in (I) and (II) were significantly lower. The high correlation has been found between excretion of 5-HIIA and creatinine, indicating a similar process of excretion of both substances. Hydratation before the thermal stress exerted advantageous effect on the thermoregulation in men. The results of this study have been discussed in conjunction with the data in literature.

Adult↗
PubMed1979

Fighter index of thermal stress (FITS): guidance for hot-weather aircraft operations.

Operation of fighter and trainer aircraft at low altitude in hot weather often involves significant heat stress on aircrews. Guidance for control of this stress and its adverse consequences has not heretofore been available. The Fighter Index of Thermal Stress (FITS) was derived from the Wet Bulb Globe Temperature (WBGT) using recent in-flight data on cockpit environments and assuming a fixed contribution from solar heating. The FITS table is entered with ground dry bulb temperature and dewpoint temperature, and yields an estimate of cockpit thermal stress. Caution and Danger Zones are designated on the table, based upon typical aircrew clothing, metabolic rate, and physiological status. Appropriate protective measures are recommended, including awareness of heat stress, limitations on ground operations, allowance of adequate recovery intervals, provision for fluid intake, and cancellation of flights under severe conditions. Possible applications of FITS are discussed together with its potential impact on flight operations at 30 USAF bases.

Aerospace Medicine↗
PubMed1978

Thermal stress in teeth.

Observations of crack damage in the tooth structure from in vivo studies and in vitro experimental thermal cycling studies were combined with numerical analysis techniques to identify and isolate the influence of thermal stresses on the creation and propagation of cracks in teeth. The factors considered in this study included: (a) variations in tooth type or geometry (molar, bicuspid, etc.), (b) tooth age, (c) material properties of the tooth, (d) the magnitude of the change in the temperature of the environment surrounding the tooth, and (e) the thermal resistance between the tooth and the medium surrounding the tooth.

Adolescent↗
PubMed1978

Numerical and experimental evaluation of energy inputs, temperature gradients, and thermal stresses during restorative procedures.

Wet cutting in enamel should be used during restorative procedures. According to evidence reported here, dry cutting can induce sufficiently high thermal stresses to fracture the enamel. Temperatures resulting from dry cutting in dentin are high enough to cause biologic pulp damage if the cutting is within 1 to 2 mm of the pulp. Cracks induced in the cavity walls by dry cutting may eventually contribute to marginal failure. A hand-held syringe directing a small, high-velocity stream of water into the cutting region is a more effective cooling technique than an air-water spray.

Adult↗
PubMed2026

Epitranscriptomic erasers in bivalves: Evolutionary divergence and species-specific transcriptional plasticity of the ALKBH family under acute thermal stress.

The AlkB homolog (ALKBH) family of Fe(II)/α-ketoglutarate-dependent dioxygenases mediates nucleic acid demethylation, thereby governing RNA metabolism and genomic stability. Despite their pivotal roles in epitranscriptomic regulation across vertebrates, the evolutionary dynamics and functional significance of ALKBH proteins in bivalve mollusks remain largely unexplored. Here, we present a comprehensive phylogenomic analysis of 210 ALKBH genes identified across 35 bivalve species. Our analyses reveal a distinct evolutionary trajectory characterized by the lineage-specific loss of ALKBH4 and the restricted distribution of ALKBH5 to the Mytilidae family, contrasting sharply with vertebrate repertoires. Using the noble scallop (Chlamys nobilis) and Pacific oyster (Crassostrea gigas) as model systems, we demonstrate that ALKBH genes exhibit conserved spatiotemporal expression patterns, with pronounced enrichment in gonadal tissues and during metamorphic transitions, implicating these enzymes in gametogenesis and larval development. Furthermore, comparative thermal stress experiments reveal divergent transcriptional plasticity: the subtropical scallop C. nobilis mounts rapid, transient induction of ALKBH1/2/6 under heat shock, whereas the eurythermal oyster C. gigas maintains sustained ALKBH3 expression, potentially underpinning its superior thermal tolerance. Conversely, cold stress elicits bimodal regulation in C. nobilis, with ALKBH1/2 upregulation contrasting with ALKBH6/7/8 suppression. These findings illuminate the functional diversification of bivalve ALKBH genes and their potential utility as molecular biomarkers for assessing developmental competence and thermal resilience in shellfish aquaculture.

Animals↗
PubMed1979

Influence of acute thermal stress and maternal diet on metabolic rate of obese (ob/ob) and lean mice at two weeks of age.

The metabolic response of one- and two-week-old obese (ob/ob) and lean mice to acute thermal stress, and the influence of maternal diet on body fat and metabolic rates of these mice, were evaluated. Both obese and lean pups increased their rate of oxygen consumption 62 to 67% when exposed to 25 degrees C for 20 minutes rather than to 35 degrees C. Obese pups exposed to an intermediate temperature (30 degrees C), however, increased their rate of oxygen consumption less (35%) than did lean mice (55%) exposed to the same temperature. Reports in the literature suggest that adult obese mice have a markedly reduced ability to increase their oxygen consumption when cold-stressed, but the present results indicate that young obese mice may have less impairment in their capacity to increase oxygen consumption. Two-week-old obese pups contained more fat and consumed less oxygen than lean littermates. The maternal diet was manipulated to increase the body fat content of two-week-old pups to equal that of obese mice, but obese pups still consumed less oxygen than did the lean pups. We, thus, conclude that factors other than differences in body fat content are responsible for the lowered oxygen consumption observed in young obese mice.

Adipose Tissue↗
PubMed1977

Diluent sensitivity in thermally stressed cells of pseudomonas fluorescens.

Thermally injured cells of Pseudomonas fluorescens were unable to produce colonies on Trypticase soy agar (TSA) after dilution with 0.1% peptone. Nutritional exigency could not be used as the criterion for this injury, since varying the composition of the plating medium had little effect on the number of colonies that developed. The injured cells had no requirement for compounds known to leak out during the heat treatment in order to recover. The cells did not exhibit injury if dilution preceded heat treatment on the plating medium, demonstrating that the heat treatment sensitized the cells to the trauma of dilution. Substitution of 0.1% peptone with growth medium as the diluent largely offset the previously observed drop in TSA count. Little difference in survival was observed when monosodium glutamate or the balance of the defined medium was used as the diluent. The diluent effect was ionic rather than osmotic. The presence of cations was important in maintaining the integrity of the injured cell, and divalent cations enhanced this protective effect. The role of these cations at the level of the cell envelope is discussed.

Cations, Divalent↗
PubMed1977

cAMP in temperature- and ADH-regulating centers after thermal stress.

cAMP concentrations in temperature-regulating sites of the brain and plasma osmolality were measured after exposure of male rats to 36 degrees C and 37-42% rh. for 10, 20, or 30 min. Plasma osmolality was affected by none of the heat exposures. In both the preoptic area and the posterior medial hypothalamus, cAMP concentrations were increased compared to controls, after 10, 20 and 30 min of heat exposure. In the supraoptic-paraventricular nuclei, neither 10 nor 20 min of exposure resulted in augmented cAMP concentrations; but after 30 min of heat exposure, cAMP levels in these nuclei were significantly greater than in controls. Neurohypophysial cAMP concentrations were increased after both 10 and 30 min of exposure. Cerebral cortical cAMP concentrations were not affected by thermal stress. It is concluded that cAMP is involved in the neural mechanisms which are brought into play to regulate body temperature during acute heat exposure. The significance of this involvement and its relation to the overall temperature-regulating mechanisms of the body are discussed.

Animals↗
PubMed1978

Antimetabolite sensitivity and magnesium uptake by thermally stressed Vibrio parahaemolyticus.

Metabolic inhibitors were added to a culture medium inoculated with theramlly stressed Vibrio parahaemolyticus to obtain information pertaining to biosynthetic processes required for recovery from heat damage. Ribonucleic acid and protein syntheses, in addition to membrane repair, were required during recovery of injured cells. Neither nucleic acid nor Mg2+ leakage was noted to occur during the time cells were subjected to heat stress. Studies revealed that Mg2+ was apparently taken up by cells of V. parahaemolyticus during the first 30 min after thermal treatment, indicating a possible increased requirement for Mg2+ for membrane and/or ribosome stability and repair.

Anti-Bacterial Agents↗
PubMed1978

The cavity sealing ability of composite restorations subjected to thermal stress.

An artificial caries technique, using a diffusion controlled acidified gel, was used to create in vitro artificial lesions adjacent to composite restorations. Prior to gel immersion, test specimens were temperature-cycled in a machine designed specifically for this purpose. Examination of control specimens showed little evidence of leakage, the presence of a cavity wall lesion being used as an indication of leakage. Compared to the controls, the test specimens showed either a reduction or no change in leakage pattern. It is suggested that thermal percolation may not be of clinical significance in relation to composite restorations.

Absorption↗
PubMed1978

Peripheral T lymphocytopenia under exogenous thermal stress.

A transient decrease in T lymphocytes in peripheral blood was observed in twelve healthy volunteers immersed in hot water baths which raised their mean rectal temperature by 1.35 C. T lymphocytes declined from 59 to 41 rel % (2p less than 0.001) or from a mean of 1990 to 1300 per mm3. T lymphocytopenia was accompanied by a relative increase in the fraction of B lymphocytes. Total lymphocyte count remained unchanged. In vitro heating alone to 39 C did not influence the total of SRBC-labelled lymphocytes. The findings are interpreted to be the result of a change in lymphocyte distribution with increased recirculation of mobile T lymphocytes.

Adult↗
PubMed1977

Diencephalic efflux of calcium ions in the monkey during exercise, thermal stress and feeding.

1. The diencephalon of the unanaesthetized macaque monkey was radio-labelled with calcium by a microinjection of 6-8 muC (45)Ca(2+) into the third cerebral ventricle through a permanently implanted cannula. Successive 5 min push-pull perfusions of the mid-line hypothalamic region with an artificial C.S.F. were carried out at a rate of 28 mul./min every 20 min. A washout curve of declining (45)Ca(2+) radioactivity was thus generated.2. When the monkey exercised strenuously on a special ;rowing machine' to obtain highly palatable banana pellets, its body temperature rose sharply. As the monkey exercised, during a sequence of push-pull perfusions, the concurrent efflux of (45)Ca(2+) ions increased markedly in the corresponding samples of diencephalic perfusate. This enhanced activity of calcium ions continued throughout a 30 min work period and persisted as long as the monkey's temperature was elevated in the interval immediately following exercise.3. Exposure of the monkey's trunk, between neck and thigh to cold air of 5 degrees C likewise augmented the amount of (45)Ca(2+) ions in the diencephalic push-pull perfusates; however, a similar exposure to air warmed to 35 degrees C failed to alter the pattern of (45)Ca(2+) efflux from the animal's diencephalon. If a fasted monkey consumed only the banana pellets but was not exercised, the level of (45)Ca(2+) in the perfusate also increased transiently, just at the onset of feeding.4. We conclude that a local change in calcium transport, binding or other cellular activity of the cation within the diencephalon could play an important role in the central mechanism underlying the set-point rise in a primate's temperature which accompanies vigorous exercise. Further, the results support the idea that this cation functions in the diencephalic control of metabolic heat production as well as in the overall processes of energy metabolism, particularly in relation to feeding.

Animals↗
PubMed1978

Lactose variability of Escherichia coli in thermally stressed reactor effluent waters.

Lactose-utilizing and nalidixic acid-resistant populations of Escherichia coli, having an optimum growth temperature of 37 degrees C, were placed in modified diffusion chambers. The chambers were submerged in the epilimnion and hypolimnion of a 1,100-hectare lake (Par Pond) which receives cooling water from a nuclear production reactor. Control chambers were placed in a deep-water reservoir and a Flowing-Streams Laboratory, both of which had comparable temperatures to Par Pond. The populations of E. coli were sampled regularly for up to 3 weeks. Viability of the bacteria was determined by dilution plating to nutrient agar followed by replicate plating onto selective medium to determine lactose utilization and nalidixic acid sensitivity. Initial populations of E. coli were lactose positive but changed to lactose negative in Par Pond when the reactor was operating (i.e., cooling water from the heat exchangers was being discharged to the lake). This alteration occurred most rapidly in the chambers closest to the cooling-water discharge point. Such changes did not occur in a deep-water reservoir, in Par Pond when the reactor was not operating, or in the Flowing-Streams Laboratory. The nalidixic acid-resistant characteristic remained stable regardless of the chambers' placement or reactor operations. Although the reasons for such alterations are unclear, it appears that lactose-negative populations of E. coli are selected for in these reactor effluent waters. The loss of the lactose characteristic prevents the recognition and identification of E. coli in this cooling lake (when the reactor is operating) and may prevent the assessment of water quality based on coliform recognition.

Drug Resistance, Microbial↗