Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Cold tolerance”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 469 records · Page 26Linked to original sources
PubMed1976

Nonshivering thermogenesis induced by repetitive hypothalamic cooling in the rat.

The effect of prolonged and repetitive cooling of the preoptic/anterior hypothalamic area on the sensitivity to the metabolic effect of noradrenaline and on the resistance to cold exposure was studied in the white rat. The preoptic area of 18 unanesthetized animals was cooled 9 h/day 5 days/wk, for a total of 80-150 h. One hour after a noradrenaline test injection (0.4 mg/kg), the experimental animals in which the preoptic area had been cooled to about 24 degrees C increased oxygen uptake by 81%, whereas those in which the preoptic area had been cooled to about 28 degrees C increased oxygen uptake by 48% (the control animals by only 37%). Despite their increased capacity for nonshivering thermogenesis, the experimental animals did not tolerate cold exposure (-10 degrees C) better than the controls. This development of nonshivering thermogenesis is thought to have been mediated by the hypothalamic temperature-sensitive neurons, and the possibility that it could explain the shift from shivering to nonshivering thermogenesis seen during adaptation to cold is discussed.

Animals↗
PubMed2001

A Ca(2+)-dependent protein kinase that endows rice plants with cold- and salt-stress tolerance functions in vascular bundles.

A rice Ca(2+)-dependent protein kinase, OsCDPK7, is a positive regulator commonly involved in the tolerance to cold and salt/drought. We carried out in situ detection of the transcript and immunolocalization of the protein. In the wild-type rice plants under both stress conditions, OsCDPK7 was expressed predominantly in vascular tissues of crowns and roots, vascular bundles and central cylinder, respectively, where water stress occurs most severely. This enzyme was also expressed in the peripheral cylinder of crown vascular bundles and root sclerenchyma. Similar localization patterns with stronger signals were observed in stress-tolerant OsCDPK7 over-expressing transformants with the cauliflower mosaic virus 35S promoter. The transcript of a putative target gene of the OsCDPK7 signaling pathway, rab16A, was also detected essentially in the same tissues upon salt stress, suggesting that the OsCDPK7 pathway operates predominantly in these regions. We propose that the use of the 35S promoter fortuitously strengthened the localized expression of OsCDPK7, resulting in enhancement of the stress signaling in the inherently operating regions leading to improved stress tolerance.

Adaptation, Physiological↗
PubMed1999

UCP1: the original uncoupling protein--and perhaps the only one? New perspectives on UCP1, UCP2, and UCP3 in the light of the bioenergetics of the UCP1-ablated mice.

The availability of a UCP1-ablated mouse has enabled critical studies of the function of UCP1, UCP2, and UCP3. Concerning UCP1, its presence in brown-fat mitochondria is associated with innate uncoupling, high GDP-binding capacity, and GDP-inhibitable Cl- permeability and uncoupling--but the high fatty acid sensitivity found in these mitochondria is observed even in the absence of UCP1. The absence of UCP1 leads to low cold tolerance but not to obesity. UCP1 ablation also leads to an augmented expression of UCP2 and UCP3 in brown adipose tissue, making this tissue probably the one that boasts the highest expression of these UCPs. However, these very high expression levels are not associated with any inherent uncoupling, or with a specific GDP-binding capacity, or with a GDP-sensitive Cl- permeability, or with any effect of GDP on mitochondrial membrane potential, or with an increased basal metabolism of cells, or with the presence of norepinephrine- or fatty acid-induced thermogenesis in cells, and not with a cold-acclimation recruited, norepinephrine-induced thermogenic response in the intact animal. Therefore, it can be discussed whether any uncoupling effect is associated with UCP2 or UCP3 when they are endogenously expressed and, consequently, whether (loss of) uncoupling (thermogenic) effects of UCP2 or UCP3 can be invoked to explain metabolic phenomena, such as obesity.

Adipose Tissue, Brown↗
PubMed1984

Metabolic responses to tyramine and cold in young male Sprague-Dawley and Fischer 344 rats.

Significant differences in responses to intraperitoneally injected tyramine or cold exposure (-10 degrees C) were observed in young (3-4 mo) male Sprague-Dawley (S-D) and Fischer 344 (F344) rats cold-acclimated (CA) or non-cold-acclimated (non-CA). Non-CA S-D and F344 rats respond to tyramine by increased O2 uptake and elevation of colonic temperature, but, as we had reported previously, the optimal doses of tyramine required was significantly different for these two strains, i.e., 2 mg/kg for F344 vs. 20 mg/kg for S-D. The response to tyramine was significantly potentiated by cold acclimation in both strains of rats. Despite the different dosages of tyramine given to the animals, similar increases in O2 uptakes and colonic temperatures were observed. Differences between these two strains were also evident in their responses to a cold challenge (3 h, -10 degrees C). The ranking for cold tolerance (-10 degrees C) was as follows: CA F344 greater than non-CA F344 greater than CA S-D greater than non-CA S-D. These differences between the two strains suggest that interpretations regarding the response of rats to stressful conditions must be made with caution and appreciation of strain differences.

Acclimatization↗
PubMedDate not supplied

Maternal-fetal relations in antifreeze production in the eelpout Zoarces viviparus.

The viviparous teleost Zoarces viviparus inhabits the coastal areas of the eastern North Atlantic and Baltic region. Antifreeze activity was measured in serum from pregnant females and embryos during their embryological development inside the ovary and found to be up to 0.95 degree C and 0.85 degree C respectively. Lower levels of antifreeze activity (up to 0.34 C) were discovered in the ovarian fluid. The result is higher hysteresis freezing points and thus less protection to freezing of the ovarian fluid compared to the serum in embryos and the maternal organism. The pertinence of this to the cold tolerance of Z. viviparus is presently unknown. SDS-PAGE of ovarian fluid shows only few protein bands and a difference in proportional density of proteins compared to maternal and embryo serum. This could indicate that another mechanism than rupture of blood vessels in the ovarian wall is of importance for the occurrence of small proteins in the ovarian fluid.

Animals↗
PubMed2002

Two uncoupling protein genes of rice (Oryza sativa L.): molecular study reveals the defects in the pre-mRNA processing for the heat-generating proteins of the subtropical cereal.

The recent finding of uncoupling proteins (UCPs) in plants has demonstrated that plant mitochondria contain at least two distinct types of potential heat-generating protein, i.e. uncoupling proteins (UCPs) and alternative oxidases. In this study, we isolated and characterized two rice genes encoding UCPs with the aim of improving cold tolerance of rice through the modification of UCP expression. The two rice nuclear genes, OsUCP1 and OsUCP2, appeared to encode functional UCPs, as far as the amino acid sequences of the gene products showed. However, our study revealed that the processing of the pre-mRNAs of both genes was defective. The defects in the pre-mRNA processing resulted in multiple abnormal forms of the transcripts, whose translation products seemed not to retain normal UCP activities. No OsUCP cDNA clones corresponding to the normal transcripts were detected in our study. A northern analysis, on the other hand, revealed that neither of the OsUCP genes exhibited cold-enhanced expression, whereas the gene expression for an alternative oxidase was strikingly enhanced in cold-treated leaves of rice. Our present data thus indicate that rice leaves, placed in cold environments, do not express functional UCPs.

Alternative Splicing↗
PubMed2003

Temperature dependence of the Ca2+-ATPase (SERCA2) in the ventricles of tuna and mackerel.

Recent physiological studies on the cardiovascular performance of tunas suggest that the elevated heart rates of these fish may rely on increased use of intracellular sarcoplasmic reticulum (SR) Ca2+ stores. In this study, we compare the cellular cardiac performance in endothermic tunas (bluefin, albacore, yellowfin) and their ectothermic sister taxa (mackerel) in response to acute temperature change. The cardiac sarco/endoplasmic reticulum Ca2+-ATPase (SERCA2) plays a major role during cardiac excitation-contraction (E-C) coupling, transporting Ca2+ from the cytosol into the lumen of the SR and thus promoting the relaxation of the muscle. Measurements of oxalate-supported Ca2+ uptake in SR-enriched ventricular vesicles indicated that tunas were capable of sustaining a rate of Ca2+ uptake that was significantly higher than the mackerel. Among tunas, the cold-tolerant bluefin had the highest rates of SR Ca2+ uptake and ATPase activity. The differences among Ca2+ uptake and ATP hydrolysis rates do not seem to result from intrinsic differences between the SERCA2 present in the different tunas, as shown by their similar temperature sensitivities and similar values for activation energy. Western blots reveal that increased SERCA2 protein content is associated with the higher Ca2+ uptake and ATPase activities seen in bluefin ventricles compared with albacore, yellowfin, and mackerel. We hypothesize that a key step in the evolution of high heart rate and high metabolic rate in tunas is increased activity of the SERCA2 enzyme. We also suggest that high levels of SERCA2 in bluefin tuna hearts may be important for retaining cardiac function at cold temperatures.

Animals↗
PubMed1992

Lateral and Rotational Mobilities of Lipids in Specific Cellular Membranes of Eucalyptus gunnii Cultivars Exhibiting Different Freezing Tolerance.

Two cell lines of Eucalyptus gunnii have been shown to keep their differential frost tolerance at the cellular level after long-term culture. They have been used to investigate the fluidity of specific cell membranes in relation with frost tolerance. Protoplasts and isolated vacuoles were obtained from both cell lines. In addition, purified plasma membrane and tonoplast (the vacuolar membrane) were separated from a crude microsomal fraction through free-flow electrophoresis. The lateral and rotational mobilities of lipids in these different membranes were studied by two biophysical techniques: fluorescence recovery after photobleaching (FRAP) and fluorescence polarization. After labeling the vacuoles isolated from the frost-sensitive cells with 1-oleoyl-2-(7-nitro-2,1,3-benz-oxadiazol-4-yl)aminocaproyl phosphatidylcholine, a single mobile component was observed with a diffusion coefficient of 2.4 x 10(-9) cm(2) s(-1) and a mobile fraction close to 100% at a temperature of 23 degrees C. When using isolated vacuoles from the frost tolerant line, a higher lateral diffusion of tonoplast lipids was found with a diffusion coefficient of 3.2 x 10(-9) cm(2) s(-1), still with a mobile fraction close to 100%. No convincing data were obtained when performing fluorescence recovery after photobleaching experiments on protoplasts. Fluorescence polarization experiments confirmed the differential behavior of the two cell lines for tonoplast and also for plasma membrane. In addition, they showed that intrinsically tonoplast exhibited a higher fluidity than plasma membrane. Our results provide the first information on the fluidity of tonoplast and on the compared properties of two important plant membranes-tonoplast and plasma membrane-through the use of two complementary biophysical approaches. In addition, they suggest there is a correlation between membrane fluidity and cold tolerance. The potential interest of plant vacuole as a natural model system in membrane studies is emphasized.

Journal Article↗
PubMed2005

Molecular and structural characterization of barley vernalization genes.

Vernalization, the requirement of a period of low temperature to induce transition from the vegetative to reproductive state, is an evolutionarily and economically important trait in the Triticeae. The genetic basis of vernalization in cultivated barley (Hordeum vulgare subsp. vulgare) can be defined using the two-locus VRN-H1/VRN-H2 model. We analyzed the allelic characteristics of HvBM5A, the candidate gene for VRN-H1, from ten cultivated barley accessions and one wild progenitor accession (subsp. spontaneum), representing the three barley growth habits - winter, facultative, and spring. We present multiple lines of evidence, including sequence, linkage map location, and expression, that support HvBM5A being VRN-H1. While the predicted polypeptides from different growth habits are identical, spring accessions contain a deletion in the first intron of HvBM5A that may be important for regulation. While spring HvBM5A alleles are typified by the intron-localized deletion, in some cases, the promoter may also determine the allele type. The presence/absence of the tightly linked ZCCT-H gene family members on chromosome 4H perfectly correlates with growth habit and we conclude that one of the three ZCCT-H genes is VRN-H2. The VRN-H2 locus is present in winter genotypes and deleted from the facultative and spring genotypes analyzed in this study, suggesting the facultative growth habit (cold tolerant, vernalization unresponsive) is a result of deletion of the VRN-H2 locus and presence of a winter HvBM5A allele. All reported barley vernalization QTLs can be explained by the two-locus VRN-H1/VRN-H2 model based on the presence/absence of VRN-H2 and a winter vs. spring HvBM5A allele.

Alleles↗
PubMed1990

The effect of local temperature versus sympathetic tone on digital perfusion in Raynaud's phenomenon.

Matched groups of 7 to 8 patients with primary Raynaud's phenomenon, systemic sclerosis, and undifferentiated connective tissue disease and cold-tolerant normal control subjects were studied by simultaneous digital strain gauge plethysmography and laser Doppler capillary velocimetry during two controlled cycles of hand warming and cooling with and without addition of central cooling and during clinical maneuvers to evoke sympathetic tone. Transient vasoconstrictor responses of comparable degree could be evoked in all patient groups and in both the arterial and microvascular beds. While the addition of central cooling had little influence on arterial flow, patients with systemic sclerosis manifested a failure to maintain nutritive perfusion at finger temperatures associated with Raynaud's phenomenon. Linear regression and multivariate analysis suggested that finger temperature was the principal determinant of arterial flow in systemic sclerosis and that arterial flow was the principal determinant of microvascular perfusion. The inability of patients with systemic sclerosis to maintain nutritive flow in the face of either reflex or cold-induced proximal arterial constriction is consistent with their clinical propensity to ischemic tissue injury and separates these patients physiologically from other forms of Raynaud's phenomenon.

Adult↗
PubMed1975

[Normal data for hemorrhagometry (author's transl)].

Normal data for hemorrhagometry were established in 43 control persons, aged between 4 and 14 years. At room temperature the mean value for bleeding time was 4.61 min. (upper limit of normal 7.7 min.), the mean hemoglobin loss, which corresponds to the blood loss, was 4.34 mg (upper limit 14.74 mg), the mean value for maximal bleeding intensity was 21.4 mug hemoglobin/sec. (upper limit 48.8). When hemorrhagometry is performed at 17 degrees C (cold tolerance test) bleeding time is prolonged (mean 9.02 min., upper limit 14.3 min.), bleeding intensity increases (mean 32.4 mug Hb/sec., upper limit 81.3 mug/sec.), and hemoglobin loss rises (mean 11.07 mg, upper limit 31.36 mg). Bleeding time determinations according to IVY yield shorter values (mean 2.99 min., upper limit 4.5 min.) than those obtained by hemorrhagometry at room temperature. There was no positive correlation between hemorrhagometry parameters and age, sex, and number of thrombocytes, as long as thrombocyte counts above 100.000/mm3.

Adolescent↗
PubMed2003

Repeated immobilization stress increases uncoupling protein 1 expression and activity in Wistar rats.

Repeat immobilization-stressed rats are leaner and have improved cold tolerance due to enhancement of brown adipose tissue (BAT) thermogenesis. This process likely involves stress-induced sympathetic nervous system activation and adrenocortical hormone release, which dynamically enhances and suppresses uncoupling protein 1 (UCP1) function, respectively. To investigate whether repeated immobilization influences UCP1 thermogenic properties, we assessed UCP1 mRNA, protein expression, and activity (GDP binding) in BAT from immobilization-naive or repeatedly immobilized rats (3 h daily for 4 weeks) and sham operated or adrenalectomized (ADX) rats. UCP1 properties were assessed before (basal) and after exposure to 3 h of acute immobilization. Basal levels of GDP binding and UCP1 expression was significantly increased (140 and 140%) in the repeated immobilized group. Acute immobilization increased GDP binding in both naive (180%) and repeated immobilized groups (220%) without changing UCP1 expression. In ADX rats, basal GDP binding and UCP1 gene expression significantly increased (140 and 110%), and acute immobilization induced further increase. These data demonstrate that repeated immobilization resulted in enhanced UCP1 function, suggesting that enhanced BAT thermogenesis contributes to lower body weight gain through excess energy loss and an improved ability to maintain body temperature during cold exposure.

Adipose Tissue, Brown↗
PubMedDate not supplied

Low-temperature biodegradation of high amounts of phenol by Rhodococcus spp. and basidiomycetous yeasts.

Four cold-adapted microbial strains able to degrade high amounts of phenol were isolated from hydrocarbon-contaminated alpine soils. Two of the strains were bacteria identified as Rhodococcus spp., and two strains were basidiomycetous yeasts. One of the yeasts was identified as Trichosporon dulcitum, while the second yeast strain belonged to the Urediniomycetes and probably represents a novel species. This strain was not able to grow at temperatures above 20 degrees C, while the other three strains were cold-tolerant and could grow at temperatures ranging from 1-25 degrees C (T. dulcitum) or 1-30 degrees C (rhodococci). The yeast strains were characterized by a substantially lower optimum temperature for growth and biodegradation compared to the bacteria. The urediniomycete strain degraded 5 mM phenol at 1 degrees C faster than the two bacteria at 10 degrees C. The optimum temperature for phenol degradation was 10 degrees C (novel yeast species), 20 degrees C (T. dulcitum), or 30 degrees C (rhodococci). Using fed-batch cultivation in mineral medium with phenol as the sole carbon source, high amounts of phenol were degraded at 10 degrees C. Both rhodococci degraded up to 12.5 mM phenol, while the two yeast strains even utilized as much as 15 mM phenol.

Basidiomycota↗
PubMed1990

The effect of sympathetic blockade and cooling in Raynaud's phenomenon.

Nineteen patients with Raynaud's phenomenon (12 suffering from generalized scleroderma [GS] and seven from primary Raynaud's phenomenon [PR] and seven cold-tolerant healthy women underwent a cooling challenge with combined body and finger cooling. Finger systolic blood pressure was measured at 30 and 15 degrees C, before and after nervous blockade at the finger-base with lidocain. Finger/arm blood pressure ratio (FBP/armBP) at 30 degrees C was significantly lower in GS as compared to controls and PR, and it did not change after nervous blockade in any group. FBP/armBP at 15 degrees C, decreased to zero in all patients with Raynaud's phenomenon and to median 0.67 in controls, prior to nervous blockade. After nervous blockade, in response to cooling, FBP/armBP at 15 degrees C decreased significantly and was comparable in all groups. We conclude that the sympathetic nervous system seems to play an important part in provoking Raynaud's phenomenon in PR and most GS.

Adult↗
PubMed1990

Cyanosis and Raynaud's phenomenon: the relation to underlying disease and venous abnormalities.

Matched groups of 7 to 8 patients with primary Raynaud's phenomenon, systemic sclerosis, and undifferentiated connective tissue disease and cold tolerant normal control subjects were studied by simultaneous digital strain gauge plethysmography and laser Doppler capillary velocimetry during two controlled cycles of hand warming and cooling. Nailfold capillaroscopic assessments and measures of in vivo platelet activation were performed. Triphasic color changes were present in all patients with systemic sclerosis, in 6 of 8 with undifferentiated connective tissue disease, but in only 1 of 7 with primary Raynaud's phenomenon. The occurrence of cyanosis correlated with evidence of impaired venous volume by strain gauge plethysmography and with higher degrees of capillary loop architectural abnormalities. The authors conclude that the presence of digital cyanosis is indicative of connective tissue disease and related to evidence of impaired digital venous capacitance. This may underlie the frequent presence of edema in these patients and may be implicated in the pathogenesis of capillary loop abnormalities.

Adult↗
PubMed2005

Interpopulational variation in recovery time from chill coma along a geographic gradient: a study in the common woodlouse, Porcellio laevis.

Extreme temperatures restrict the performance of terrestrial arthropods and variations in low temperatures on a latitudinal scale influence physiological variables. Recovery time from chill coma is a measure of cold tolerance and it is a good index of climatic adaptation. We tested differences in recovery time of the common woodlouse (Porcellio laevis) exposed to different thermal conditions. Individuals were sampled from four different populations in Chile, spanning a latitudinal range of approximately 10 degrees . Significant differences were found in recovery time among experimental temperatures and among populations, but no interaction between these factors. The results of recovery time in P. laevis showed a positive increment with annual mean minimum temperature, indicating that there is geographical variation in recovery time. While body mass presented interpopulational variation, this variation was not associated with thermal variables or latitude. Overall, our results agree with previous studies in the sense that recovery time from chill coma decreases towards high latitudes, and it is independent of taxa, continent and hemisphere.

Adaptation, Physiological↗
PubMed2006

Larval tolerance, gene flow, and the northern geographic range limit of fiddler crabs.

Despite growing interest in species' range shifts, little is known about the ecological and evolutionary factors that control geographic range boundaries. We investigated the processes that maintain the northern range limit of the mud fiddler crab (Uca pugnax) at North Scituate, Massachusetts, USA (42 degrees 14' N), located approximately 60 km north of Cape Cod. Larvae from five populations in Massachusetts were reared under controlled temperatures to test whether cooler water near the edge of this species' range inhibits planktonic development. Few larvae completed development at temperatures < 18 degrees C, a threshold that larvae would regularly encounter north of Cape Cod. Extensive salt marshes are present north of the current range boundary, and a transplant experiment using field enclosures confirmed that benthic fiddler crabs can survive severe winter conditions in this northern habitat. Taken with oceanographic data, these results suggest that the range boundary of fiddler crabs is likely maintained by the influence of cooler water temperatures on the larval phase. Analyses of mitochondrial DNA sequences from a neutral marker (COI) indicate high gene flow among U. pugnax populations in Massachusetts with little differentiation across Cape Cod. Consistent with predictions regarding the homogenizing influence of gene flow, larvae from source populations north and south of Cape Cod shared a common lower threshold for development. However, larvae produced near the range edge had faster growth rates than those from the south side of Cape Cod (typically reaching the final megalopal stage 1.0-5.5 d faster at 18 degrees C). Additional studies are needed to determine the mechanism underlying this counter-gradient variation in development time. We hypothesize that dispersal into cooler water on the north side of Cape Cod may act as a selection filter that sieves out slow developers from the larval pool by increasing planktonic duration and exposure to associated sources of mortality. Thus while high gene flow may prevent the evolution of greater cold tolerance in northern populations, recurrent selection on existing variation may lead to an unexpected concentration of favorable adaptations at the edge of the range. Such a pattern could permit edge populations to play a dominant and unrecognized role in future range extensions.

Animals↗
PubMed1982

Sympathetic activity in thyroid-treated Zucker rats.

Treatment of lean and obese 3- to 4-mo-old male Zucker rats with 0.03% thyroid powder (TP) for up to 41 days produced a decreased weight gain and carcass lipid content in obese but not lean rats, without reduction in food intake. Improved thermogenesis in TP-treated obese rats was evidenced by increased basal rectal temperatures and improved cold tolerance, although TP did not alter the lower stress-evoked levels of plasma norepinephrine (NE) or epinephrine of the obese rats. Levels of NE and/or NE turnover were lower in hearts, aortas, pancreata, interscapular brown adipose, and epididymal white adipose pads of obese compared with lean rats. Both NE levels and turnover were increased in the hearts and aortas of TP-treated obese rats, suggesting increased sympathetic activity in these organs. Basal but not stress-evoked hyperglycemia, hyperinsulinemia, and hyperglycerolemia in the obese rats were partly or totally corrected by TP treatment as was defective in vivo utilization of fatty acids. Therefore 0.03% TP administration had a selective effect on the obese Zucker rat compared with the lean and led to decreased weight gain associated with improved thermogenesis. These effects appeared to be related in part to increased sympathetic function in some organs and improved utilization of fatty acids.

Animals↗