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PubMed1998

Cloning and sequencing of proliferating cell nuclear antigen (PCNA) from the flesh fly, Sarcophaga crassipalpis, and its expression in response to cold shock and heat shock.

We report the isolation and sequencing of a 1326 bp cDNA fragment encoding the cell-cycle proliferation protein ScPCNA from the flesh fly, Sarcophaga crassipalpis. The amino acid (aa) sequence shows 91% and 79% identity to Drosophila melanogaster and Bombyx mori proliferating cell nuclear antigen (PCNA), respectively. The coding sequence is interrupted by a single intron of 60 bp, resulting in a deduced aa sequence of 260 residues. The gene is transcribed as a single mRNA (approx. 1.2 ) as determined by Northern blot hybridization. Following a cold shock at -10 degrees C for 1 h, expression of ScPCNA decreased in S. crassipalpis whole-body mRNA, suggesting a possible cell-cycle arrest in response to a cold shock. One hour after removal from cold shock, ScPCNA transcript levels were restored to the control level. By contrast, a 1 h heat shock at 45 degrees C did not alter expression of ScPCNA.

Amino Acid Sequence↗
PubMed1984

Abnormalities of the cardiovascular response to cold pressor test in type 1 diabetes. Correlation with blood glucose control.

Left-ventricular (LV) function in type 1 diabetics without clinical heart disease was compared with that found in matched normal subjects. Although diabetics had a normal LV ejection fraction (66% +/- 6%), they showed a trend toward smaller left ventricles. Their cardiovascular response to a cold pressor test was abnormal and cardiac function after the cold pressor test correlated with hemoglobin A1c levels: Average hemoglobin A1c was inversely related to ejection fraction and early filling volume and directly related to the ratio of pre-ejection period to ejection time (PEP/LVET) after a cold pressor test. Hemoglobin A1c at the time of study correlated more closely with PEP/LVET after cold pressor test than did the six-month average hemoglobin A1c level, suggesting that cardiac function fluctuates with recent changes in blood glucose control. Thus, even when diabetics have a normal LV ejection fraction, an abnormal cardiovascular response to stress may still be present, and such abnormalities correlate with blood glucose control.

Adult↗
PubMed2000

Chromium supplementation does not influence glucose metabolism or insulin action in response to cold exposure in mature sheep.

An isotope dilution method using [U-(13)C] glucose infusion and a glucose clamp approach were applied to determine the effects of supplemental Cr and cold exposure on blood glucose turnover rate and tissue responsiveness and sensitivity to insulin in eight sheep. The daily profiles of blood metabolites and hormones were also determined. The sheep consumed diets containing either 0 or 1 mg of Cr/kg from a high-Cr yeast and were exposed from a thermoneutral environment (20 degrees C) to a cold environment (0 to 4 degrees C) for 9 d. The experiment used a crossover design. Body weight was lost (P = 0.02) during cold exposure, regardless of Cr supplementation. Blood glucose turnover rate and the maximal glucose infusion rate did not differ between diets, but both were higher (P = 0.0004 and P = 0.0001, respectively) during cold exposure than in the thermoneutral environment. The plasma insulin concentration at half-maximal glucose infusion rate changed with neither diet nor environment. Plasma concentrations of glucose and NEFA increased (P < 0.05) during cold exposure for both diets. In sheep, Cr supplementation, 1 mg/kg of diet as high-Cr yeast, has little influence on blood glucose metabolism and insulin action, whereas cold exposure enhances both without further modification by Cr supplementation.

Animal Feed↗
PubMed2002

Simulated parachute descent in the cold: thermal responses and manual performance.

BACKGROUND: Ejection from a fighter aircraft can expose the pilot to extreme cold and windy conditions. Knowledge of the effects of such conditions on thermal responses and performance of the pilot is scarce. HYPOTHESIS: It is expected that the temperature of bare skin and fingers may decrease to the level where health and/or performance are hampered. METHODS: Seven fighter pilots performed a simulated parachute descent (SPD) at ambient temperature (Ta) of -35 degrees C and wind velocity of 10 m x s(-1). The 8-min SPD was followed by a 60-min cold exposure (CE) at Ta of -20 degrees C. Flight garments with or without immersion suit were used. During SPD the subjects performed basic survival tasks. Rectal and skin temperatures were measured and manual performance was tested. RESULTS: Thermal responses did not significantly differ between the clothing ensembles. Mean skin temperature was 28 degrees C and 27 degrees C at the end of SPD and CE, respectively. The cheek temperature was 9 degrees C (range 3.2-13.8 degrees C) at the end of SPD. Finger skin temperature was 7 degrees C and 9 degrees C at the end of SPD and CE, respectively. The subjects could perform the defined tasks during SPD while manual performance was slightly impaired during CE. CONCLUSIONS: Subjects could tolerate the 8-min SPD and the following CE in the studied conditions without a loss of vital performance in basic survival actions. However, the risk of frostbite on the uncovered skin area as well as numbness of the fingers may jeopardize pilots' health and performance during parachuting.

Adaptation, Physiological↗
PubMed2026

Distinct molecular responses to acute cold exposure revealed by comparative transcriptomic and metabolomic profiling in the bay scallop Argopecten irradians.

Acute cold stress can elicit distinct molecular responses even when bay scallop populations show similar phenotypic outcomes. We compared a seventh-generation fast-growing bay scallop line (BS) with a commercial control population (CC) during a 72-h acute cold exposure at -1&#xa0;&#xb1;&#xa0;0.3&#xa0;&#xb0;C. RNA-seq was used as the discovery layer, representative BS cold-responsive genes were evaluated by qRT-PCR, and paired LC-MS profiles provided a comparative metabolic layer. At baseline, 138 genes differed between BS and CC; after cold exposure, 134 of these baseline differences disappeared and 61 of 65 cold-state differences newly emerged. BS showed a larger transcriptomic response magnitude than CC, with 1129 cold-responsive genes compared with 28 genes in CC, and this ordering remained robust across multiple sensitivity analyses. Survival after 72&#xa0;h was identical in BS and CC (83/90, 92.2% in each population). Biochemical responses were time-dependent and marker-specific: CAT, LZM, T-SOD and T-AOC showed population-by-time interactions, whereas GSH-Px and MDA did not, and the 72-h differences were not consistently favourable to BS. Metabolomic cold effects were strongly concordant between populations, and no feature showed a significant population-by-cold interaction. Features putatively assigned to arachidonic acid metabolism were enriched, but this provider-annotated pathway signal remains exploratory because authentic-standard confirmation was not performed. These findings indicate population-specific differences in molecular responsiveness but do not establish superior cold tolerance in BS.

Animals↗
PubMed2004

The role of raffinose in the cold acclimation response of Arabidopsis thaliana.

In many plants raffinose family oligosaccharides are accumulated during cold acclimation. The contribution of raffinose accumulation to freezing tolerance is not clear. Here, we investigated whether synthesis of raffinose is an essential component for acquiring frost tolerance. We created transgenic lines of Arabidopsis thaliana accessions Columbia-0 and Cape Verde Islands constitutively overexpressing a galactinol synthase (GS) gene from cucumber. GS overexpressing lines contained up to 20 times as much raffinose as the respective wild-type under non-acclimated conditions and up to 2.3 times more after 14 days of cold acclimation at 4 degrees C. Furthermore, we used a mutant carrying a knockout of the endogenous raffinose synthase (RS) gene. Raffinose was completely absent in this mutant. However, neither the freezing tolerance of non-acclimated leaves, nor their ability to cold acclimate were influenced in the RS mutant or in the GS overexpressing lines. We conclude that raffinose is not essential for basic freezing tolerance or for cold acclimation of A. thaliana.

Acclimatization↗
PubMed2002

Capsaicin-sensitive primary afferents mediate responses to cold in rats with a peripheral mononeuropathy.

Persistent sensitivity to noxious and innocuous somatic stimuli results from peripheral nerve injury. Following chronic constriction injury (CCI) of the sciatic nerve in the rat, the hind paw ipsilateral to the injury displays significantly decreased response latencies to a noxious heat stimulus (thermal hyperalgesia), compared with the contralateral uninjured paw. The ligated paw also shows increased lifting and duration of lifting from a cooled (4 +/- 1 degrees C) surface. To characterize the peripheral nerve component of increased sensitivity to cold, CCI rats were systemically injected with the potent capsaicin analog resiniferatoxin (RTX). Twenty-four hours following RTX injection response latencies to noxious heat were significantly increased for both the ligated and unligated hind paws. In addition, increased responsiveness of the ligated paw to the cold surface was significantly attenuated. The results demonstrate that the enhanced responsiveness to cold and heat following a CCI are mediated in part by RTX-sensitive primary afferents.

Animals↗
PubMed1997

Physiological responses to cold stress during prolonged intermittent low- and high-intensity walking.

In a previous study [Am. J. Physiol. 272 (Regulatory Integrative Comp. Physiol. 41): R226-R233, 1997], the physiological responses to 240 min of intermittent low-intensity walking exercise in a cold (+5 degrees C), wet, and windy environment (Cold) may have been influenced by a 120-min preceding phase of intermittent higher-intensity exercise. Furthermore, the physiological responses observed during this latter phase may have been different if it had been more prolonged. To address these questions, active men attempted a 360-min intermittent (15 min of rest, 45 min of exercise) exercise protocol in Cold and a thermoneutral environment (+15 degrees C, Neutral) at a low (0% grade, 5 km/h; Low; n = 14) and a higher (10% grade, 6 km/h; High; n = 10) intensity. During Low, rectal temperature was lower in Cold than in Neutral, whereas O2 consumption, carbohydrate oxidation, plasma norepinephrine and epinephrine, and blood lactate were higher. During High, Cold had a similar but less marked influence on the thermoregulatory responses to exercise than during Low. In conclusion, the physiological responses to Low are similarly influenced by Cold whether or not they are preceded by High. Furthermore, during intermittent exercise up to an intensity of approximately 60% of peak O2 consumption, a cold, wet, and windy environment will influence the physiological responses to exercise and potentially impair performance.

Adult↗
PubMed1979

Plasma catecholamines and cardiovascular responses to cold and mental activity.

Plasma epinephrine (E) and norepinephrine (NE) as well as blood pressure and heart rate variations were measured in 12 male subjects before, during, and after a cold hand test (5 degrees C for 2 min), a mental arithmetic test, and a combination of both these tests. Although the cold and mental tests had comparable effects on blood pressure, the heart rate response was greater than the mental test. The mental test produced a greater increase of E than the cold test, but the effect of the cold test was greater on NE than on E. Changes in heart rate were significantly correlated with E variations but not with NE, whereas changes in blood pressure were correlated with NE. Resting NE was correlated with resting blood pressure and resting E with resting heart rate. Finally the levels of basal E were positively correlated with the increase in E during the test. Cardiovascular changes were shown to be differently modified by a mental and a cold test. Evidence was given indicating that these changes are related to differences in E and NE responses in the presence of these tests.

Adrenal Medulla↗
PubMed1975

Maximum thermogenic response to cold in relation to the proportion of brown adipose tissue and skeletal muscle in the body and to other parameters in young lambs.

No relationship was apparent between the maximum thermogenic response of lambs to cold (summit metabolism) and the dissectable brown adipose tissue content, or the chemically extractable lipid content of the whole animal or the weight of various skeletal muscles. Correlations of summit metabolism with other parameters also suggested that the level of glucose, FFA and glycerol in the circulation, and the glycogen stores in liver and muscle, did not limit summit metabolism. However, significant correlations of summit metabolism with cardiac output and arteriovenous differences in oxygen content of blood focused attention on the possible role of the cardiovascular system and on the metabolic capability of the thermogenic tissues in determining summit metabolism.

Adipose Tissue, Brown↗
PubMed1995

Cold-induced responses in the upper respiratory tract.

Recent investigations have shown that the prevalence of bronchial asthma is higher among skiers exposed to cold and dry air than among nonskiers. The upper airway passages are responsible for warming and humidifying the inhaled air. During exercise in cold and dry air, warming and humidifying of the inhaled air continues in the bronchial tree. Under these conditions both nasal and bronchial mucosa are cooled by inspiratory air and remain cooled throughout the respiratory cycle. The air which reaches the bronchoalveolar air space is at body temperature and fully saturated in all conditions. In this article we briefly review the studies carried out regarding the effects of cold air inhalation on the upper respiratory tract.

Cold Temperature↗
PubMed1992

Peripheral vascular response to local cold stress of tropical men during sojourn in the Arctic cold region.

Peripheral vascular response to local cold stress was studied on 4 groups of volunteers by eliciting cold-induced vasodilatation (CIVD) response during immersion of right hand in cold water (4 degrees C) for 30 min, to examine whether tropical men can get acclimatized to local cold compared to temperate zone people, during Arctic cold exposure. Group A and B (10 each) were drawn from tropical region of India, while Group C and D (6 each) from temperate zone of Russia and natives of Arctic, respectively. Initial study was conducted on control Group A at Delhi. Group B was airlifted to the Arctic (70 degrees N, 38 degrees E), where measurements were done on them during the seventh week of acclimatization, then they were flown back to Delhi and retested. For comparison, study was done at the Arctic on six migrants (Group C) from temperate zone of Russia and 6 natives (Group D) of the Arctic. There was a significant improvement of CIVD response and peripheral blood flow of tropical men due to acclimatization to Arctic environment, which was similar to that of the migrants but lower than the natives. Thus local cold acclimatization is possible even in tropical men as in those of the temperate zone people.

Acclimatization↗
PubMed1992

DNA gyrase, CS7.4, and the cold shock response in Escherichia coli.

We identify the A subunit of DNA gyrase as a cold shock protein whose synthesis is sustained following transfer of exponentially growing cultures of Escherichia coli from 37 to 10 degrees C. After a lag period in which its synthetic rate declines, synthesis of the A subunit of DNA gyrase increases relative to that of total protein. The duration of the lag period in synthesis and the synthetic rate of the A subunit appear dependent on the synthesis of a rapidly induced cold shock protein, CS7.4. The promoter of the gyrA gene contains specific binding sites for the CS7.4 protein, suggesting that CS7.4 acts at the transcriptional level to facilitate continued A-subunit synthesis. As synthesis of the B subunit of DNA gyrase is also sustained during cold shock, we suggest that an increase in the amount of DNA gyrase per cell might occur, which would potentially adapt the cells for growth at reduced temperatures (10 degrees C).

Bacterial Proteins↗
PubMed1983

Sympathoadrenal responses to cold and ketamine anesthesia in the rhesus monkey.

The effect of cold exposure on the sympathoadrenal system in primates was studied with and without ketamine anesthesia in eight adult rhesus monkeys. Each monkey was placed in a primate chair at a thermoneutral temperature (25 degrees C) for 1 h (control) followed by cold exposure (12 degrees C) for 3 h or placed in a circulating water bath (28 degrees C) to induce a decrease in core temperature (Tre) to 35 and 33 degrees C. Plasma catecholamines were analyzed by high-pressure liquid chromatography with electrochemical detection (60-65% recovery, coefficient of variation = 15%). The 3-h cold exposure was associated with a 175% increase above control levels of norepinephrine (NE) and a 100% increase in epinephrine (E). Decreases were evident in Tre (0.5 degree C), mean skin temperature (Tsk, 5.5 degrees C), and mean body temperature (Tb, 2.0 degrees C). Continuous infusion of ketamine (0.65 mg . kg-1 . min-1) resulted in no change in the plasma levels of NE and E from the control levels. Tre, Tsk, and Tb all showed greater declines with the addition of ketamine infusion to the cold exposure. Water exposure (28 degrees C) under ketamine anesthesia resulted in a drop in Tre to 33 degrees C within 1 h. Plasma levels of NE and E were unchanged from control values at Tre of 35 and 33 degrees C. The data suggest that the administration of ketamine abolished both the thermoregulatory response and the catecholamine response to acute cold exposure.

Adrenal Medulla↗
PubMed1992

Phrenic and hypoglossal neural responses to cold airflow in the upper airway.

Cold air flowing through the larynx is known to alter the activities of laryngeal receptors with afferents in the superior laryngeal nerves (SLNs) and to induce reflex apnea in neonatal mammals. To examine the ventilatory response in adult animals and to explore associated upper airway motor responses, we recorded phrenic and hypoglossal neural responses to cooling the isolated larynx with cold air in decerebrate, vagotomized, paralyzed, ventilated cats. The most consistent response was phrenic inhibition, which occurred in all animals tested. Either excitation or inhibition of hypoglossal activity was seen consistently in individual cats, with the result that the group response was not statistically significant. All responses to laryngeal cooling were abolished by section of the SLNs. The findings confirm that directing cold air through the larynx causes reflex inhibition of ventilatory (phrenic) activity, but raise new questions as to how the two, directionally opposite hypoglossal responses are mediated.

Animals↗
PubMed2002

An Arabidopsis mutation in translation elongation factor 2 causes superinduction of CBF/DREB1 transcription factor genes but blocks the induction of their downstream targets under low temperatures.

Low temperature regulates gene expression in bacteria, yeast, and animals as well as in plants. However, the signal transduction cascades mediating the low temperature responses are not well understood in any organism. To identify components in low temperature signaling genetically, we isolated Arabidopsis thaliana mutants in which cold-responsive genes are no longer induced by low temperatures. One of these mutations, los1-1, specifically blocks low temperature-induced transcription of cold-responsive genes. Surprisingly, cold-induced expression of the early response transcriptional activators, C-repeat/dehydration responsive element binding factors (CBF/DREB1s), is enhanced by the los1-1 mutation. The los1-1 mutation also reduces the capacity of plants to develop freezing tolerance but does not impair the vernalization response. Genetic analysis indicated that los1-1 is a recessive mutation in a single nuclear gene. The LOS1 gene encodes a translation elongation factor 2-like protein. Protein labeling studies show that new protein synthesis is blocked in los1-1 mutant plants specifically in the cold. These results reveal a critical role of new protein synthesis in the proper transduction of low temperature signals. Our results also suggest that cold-induced transcription of CBF/DREB1s is feedback inhibited by their gene products or by products of their downstream target genes.

Amino Acids↗
PubMed2026

Integrative analysis of transcriptome and chromatin accessibility reveals promoter-proximal regulation and identifies candidate ABC transporters associated with cold stress responses in maize.

BACKGROUND: Low-temperature stress is a formidable environmental constraint that severely limits the growth and productivity of maize (Zea mays L.), particularly during the highly vulnerable early seedling stage. While cold tolerance is a critical agronomic objective, the integrated transcriptional and epigenetic regulatory mechanisms that govern this trait remain largely elusive. Characterizing these coordinated molecular networks is fundamental to the genetic enhancement of cold resilience in maize. METHODS: Using two maize inbred lines contrasting in chilling response (ZHB12 tolerant, B73 sensitive), we performed integrative time&#x2011;course RNA&#x2011;seq and ATAC&#x2011;seq to thoroughly and systematically characterize the precise dynamic interplay between gene expression and chromatin accessibility under cold stress conditions at the seedling stage. RESULTS: Physiological assessments confirmed that ZHB12 possesses superior cold tolerance, manifested by significantly attenuated electrolyte leakage and reduced foliar damage compared to B73. Transcriptomic profiling revealed a massive, time-dependent divergence in gene expression between the two genotypes, with a major regulatory transition identified at 24&#xa0;h of cold exposure. Functional enrichment analysis demonstrated that ZHB12 preferentially activates a robust defense repertoire, including Photosystem II electron transport, diterpenoid biosynthesis, and ATP biosynthetic pathways. Notably, multiple ATP-binding cassette (ABC) transporter genes were coordinately upregulated under chilling, suggesting their potential involvement in cellular homeostasis. ATAC-seq analysis indicated that cold stress is associated with chromatin remodeling in ZHB12, with increased accessibility observed in proximal promoter regions. Integrative analysis identified a core set of dual-responsive genes, in which increased promoter accessibility coincided with transcriptional upregulation. These genes were predominantly enriched in transporter activity and transcriptional regulation, suggesting potential epigenetic link to the superior stress response of ZHB12. CONCLUSION: Our findings reveal extensive transcriptional and chromatin accessibility changes in ZHB12 under cold stress. The observed associations between promoter accessibility and gene activation, particularly in genes involved in transport processes, highlight candidate regulators potentially contributing to cold tolerance. This study provides a molecular framework and identifies high-value candidate genes that may inform future efforts in breeding cold-tolerant maize, pending functional validation.

Zea mays↗