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PubMed2000

Origin and evolution of invasive naturalized material of Rhododendron ponticum L. in the British isles.

Information concerning the area of origin, genetic diversity and possible acquisition of germplasm through hybridization is fundamental to understanding the evolution, ecology and possible control measures for an introduced invasive plant species. Rhododendron ponticum is extensively naturalized in the British Isles, but it is not known whether native material in Turkey, Spain or Portugal gave rise to the naturalized material, or to what extent introgression has affected this material. Chloroplast (cp) and nuclear ribosomal DNA (rDNA) restriction fragment length polymorphisms (RFLPs) were sought which could distinguish between native material of R. ponticum, and between 15 other Rhododendron species including R. ponticum's closest relatives. Thereafter, a total of 260 naturalized accessions of R. ponticum from throughout the British Isles was examined with respect to informative polymorphisms. It was found that 89% of these accessions possessed a cpDNA haplotype that occurred in native material of R. ponticum derived almost entirely from Spain, while 10% of accessions had a haplotype unique to Portuguese material. These results therefore indicated an Iberian origin for British material. rDNA or cpDNA evidence of introgression from R. catawbiense was found in 27 British accessions of R. ponticum, and such accessions were significantly more abundant in Britain's coldest region, eastern Scotland, than elsewhere. This could indicate that introgression from R. catawbiense confers improved cold tolerance. Introgression from R. maximum and an unidentified species was also detected.

Adaptation, Physiological↗
PubMed1985

Serotonin and Raynaud's phenomenon.

No single pathophysiologic mechanism explains adequately cold-induced vasospasm in all forms of Raynaud's phenomenon. Local serotonin release from activated platelets is a contributory element in those disorders typified by structural arterial change, e.g., systemic sclerosis (scleroderma). Selective antagonism of S2-serotonergic receptors with ketanserin improves both maximal digital artery flow and cold tolerance. Platelet-derived growth factors, and serotonin itself, may contribute to the fibrotic arteriosclerosis of this disorder. In contrast, in primary (spastic) Raynaud's phenomenon, ketanserin relieves but does not prevent cold-induced vasospasm, which suggests that the role of serotonin is in maintenance of but not provocation of an attack. Antiplatelet therapies could benefit both disorders.

Blood Platelets↗
PubMed1993

Arterial spasticity and cold intolerance in relation to time after digital replantation.

Cold induced arterial vasospasm was studied in ten patients with single digit replantation, by measuring finger systolic pressure at different finger temperatures. Each patient was examined three times; within 2 weeks of surgery, after 1 year and after 3 years. The replantations were performed using long arterial and venous grafts. Cold-related vasospasm is established during the first year after trauma, and thereafter seems to be persistent. It is concluded that the subjective cold tolerance, which affects all patients after digital amputation regardless of whether replantation is performed or not, is partly due to vasospasm. It is less pronounced in patients without pathological vasospasm in the replanted digit. Cold intolerance is likely to decrease during the first 2 years after replantation, but not to disappear completely.

Adult↗
PubMed2005

Relationship between supercooling point and mortality at low temperatures in Indianmeal moth (Lepidoptera: Pyralidae).

Indianmeal moth, Plodia interpunctella (Hübner), is classified as a freeze-intolerant organism and one of the most cold-tolerant stored-product pests. The objective of this study was to determine the relationship between mortality at low temperatures after minimum exposure and the supercooling point (SCP) for laboratory-reared P. interpunctella at different stages of development. This relationship also was analyzed for field-collected, cold-acclimated fifth instars. Mean SCP of laboratory-reared larvae (i.e., feeding stage) was consistently above approximately -16 degrees C. Mean SCP of laboratory-reared pupae and adults (i.e., nonfeeding stages) and field-collected, cold-acclimated fifth instars was consistently below approximately -21 degrees CP seemed to be the boundary between survival and death for larvae. However, it seemed that a 1-min exposure was not sufficient to cause larval mortality at the SCP. Alternatively, for both pupae and adults, the SCP seemed not to play an important role in their survival at low temperatures, with significant mortality observed at temperatures higher than the mean SCP. Adults were the most susceptible to low temperatures with no survival occurring at -20 degrees C, > 3 degrees C above its mean SCP. Results of this investigation demonstrate that P. interpunctella has a different response to low temperatures depending on stage of development and cold acclimation. Classifying P. interpunctella only as a freeze-intolerant organism disregards the occurrence of prefreeze mortality in this species. Therefore, a reclassification of this species (e.g., chill tolerant or chill susceptible) based on the extent of prefreeze mortality and the temperature and time of exposure at which it occurs is suggested.

Acclimatization↗
PubMed1988

[Effects of cold acclimation and repetitive stress on stress-induced neuroendocrine response].

In order to elucidate the mechanism (S) involved in improved cold tolerance by means of enhanced non-shivering thermogenesis of the repetitively stressed rats, noradrenaline (NA) turnover of brown adipose tissue (BAT) and adrenocortical responses were investigated. (1) NA turnover of BAT in the cold-acclimated rats was greater than that in the resting controls. NA level of BAT in the cold-acclimated rats decreased to about 40% of the control level. It was thus inferred that this lower NA levels was induced by accelerated NA turnover. (2) NA turnover of BAT in the stressed rats after repetitive immobilization stress was higher than that of the non-stressed controls. Therefore, increased sympathetic activity of BAT would be one of the mechanisms of cross adaptation between cold and stress. (3) NA turnovers of BAT in the controls, the cold-acclimated rats and stressed ones were increased by acute cold exposure (-5 degrees C). NA turnovers of BAT in the controls and the stressed rats were increased by acute immobilization stress. (4) Plasma corticoids (corticosterone and deoxycorticosterone) in the cold-acclimated rats were higher than that of controls. Plasma corticoids in the controls, the cold-acclimated rats and stressed ones were increased by acute cold exposure (-5 degrees C, 15 min) and acute immobilization stress (30 min). The extents of increases in plasma corticoids in the stressed rats, but not in the cold-acclimated ones, were greater than those in the controls. It was suggested that repetitive immobilization stress could enhance nonshivering thermogenesis via an enhanced responsiveness of adrenocortical secretion to acute stress and cold. It would be concluded from these results that enhanced responses of corticoid secretion and accelerated sympathetic activity were associated with the establishment of cross adaptation between cold and stress. It was suggested that the extent of participation of these factors was not necessarily the same between the cold-acclimated and the stressed organisms.

Acclimatization↗
PubMed2005

The molecular biology of the low-temperature response in plants.

Plants growing in temperate regions are able to survive freezing temperatures from -5 degrees to -30 degrees C, depending on the species, through a process known as cold acclimation. In the last decade much work has been done on the molecular mechanisms of low temperature (LT) signal transduction and cold acclimation. Mutant studies and microarray analyses have revealed C-Repeat binding factor (CBF) -dependent and -independent signaling pathways in plants. Experimental evidence suggests the existence of 'potential LT sensors' but as yet there is no direct proof. A number of signal transducers such as various kinases/phosphatases have been demonstrated but the signal transduction pathways have not been elucidated. An understanding of the molecular basis of the signaling process, however, is of potential practical application. Designing new strategies to improve cold tolerance in crop varieties could increase the plant productivity and also expand the area under cultivation.

Acclimatization↗
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 ± 0.3 °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 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↗
PubMed1990

A rapid cold-hardening response protecting against cold shock injury in Drosophila melanogaster.

In studies of insect cold-hardiness, the supercooling point (SCP) is defined as the temperature at which spontaneous nucleation of body fluids occurs. Despite having an SCP of -20 degrees C, adults of Drosophila melanogaster did not survive exposure to -5 degrees C, which suggests that cold shock causes lethal injury that is not associated with freezing. If, however, flies were chilled at 5 degrees C, for as little as 30 min, approximately 50% of the flies survived exposure to -5 degrees C for 2h. This capacity to cold-harden rapidly was greatest in 3- and 5-day-old adults. The rapid cold-hardening response was also observed in larvae and pupae: no larvae survived 2 h of exposure to -5 degrees C, whereas 63% pupariated if chilled at 5 degrees C before subzero exposure. Similarly, although exposure of pupae to -8 degrees C was lethal, if pre-chilled at 5 degrees C 22% eclosed. This extremely rapid cold-hardening response may function to allow insects to enhance cold-tolerance in response to diurnal or unexpected seasonal decreases in environmental temperature.

Age Factors↗
PubMed2006

Cold-active winter rye glucanases with ice-binding capacity.

Extracellular pathogenesis-related proteins, including glucanases, are expressed at cold temperatures in winter rye (Secale cereale) and display antifreeze activity. We have characterized recombinant cold-induced glucanases from winter rye to further examine their roles and contributions to cold tolerance. Both basic beta-1,3-glucanases and an acidic beta-1,3;1,4-glucanase were expressed in Escherichia coli, purified, and assayed for their hydrolytic and antifreeze activities in vitro. All were found to be cold active and to retain partial hydrolytic activity at subzero temperatures (e.g. 14%-35% at -4 degrees C). The two types of glucanases had antifreeze activity as measured by their ability to modify the growth of ice crystals. Structural models for the winter rye beta-1,3-glucanases were developed on which putative ice-binding surfaces (IBSs) were identified. Residues on the putative IBSs were charge conserved for each of the expressed glucanases, with the exception of one beta-1,3-glucanase recovered from nonacclimated winter rye in which a charged amino acid was present on the putative IBS. This protein also had a reduced antifreeze activity relative to the other expressed glucanases. These results support the hypothesis that winter rye glucanases have evolved to inhibit the formation of large, potentially fatal ice crystals, in addition to having enzymatic activity with a potential role in resisting infection by psychrophilic pathogens. Glucanases of winter rye provide an interesting example of protein evolution and adaptation aimed to combat cold and freezing conditions.

Amino Acid Sequence↗
PubMed1982

Elicitation of supramaximal thermogenesis by aminophylline in the rat.

Previous studies in rats indicate that maximal thermogenesis during severe cold exposure is suppressed by overnight fasting. Since fasting depresses sympathetic activity and the activity of adrenergic receptors, both of which affect substrate mobilization in cold, the present study attempted to restore maximal thermogenesis in fasted rats by exogenous sympathomimetics and a hypoxanthine (aminophylline). In overnight-fasted rats, exogenous sympathomimetics had no effect in further enhancing maximal thermogenesis induced by exposure to severe cold (in He-O2 at -10 degrees C), indicating maximization of endogenous sympathetic discharge and saturation of adrenergic receptor binding during severe cold exposure. In contrast, aminophylline (1.25-37.5 mg/kg ip) elicited "supramaximal thermogenesis" beyond control maximums in both fasted (+19.4%) and fed +14.4%) conditions in a dose-dependent manner, resulting in improved cold tolerance and prevention of hypothermia. Since aminophylline acts distally to adrenergic receptors to increase intracellular adenosine 3',5'-cyclic monophosphate concentration, it is possible that such increases could enhance substrate mobilization to support supramaximal thermogenesis in severe cold.

Aminophylline↗
PubMed1996

Transcripts of a gene encoding a putative cell wall-plasma membrane linker protein are specifically cold-induced in Brassica napus.

We have isolated a gene and cDNA from Brassica napus encoding a hybrid-proline-rich protein. The putative protein is modular in structure. The N-terminal domain has properties of a signal peptide which would direct the protein into the ER. Amino acids 27 to 287 comprise three domains which contain high levels of proline and several other amino acids common in proline-rich cell wall proteins. These domains are characterised by repeating amino acid motifs. The C-terminal domain (amino acids 288 to 376) contains three putative membrane-spanning regions and shows a high degree of amino acid similarity to known hybrid-proline-rich proteins from several species. It is likely that the protein is secreted from the cell, located in the cell wall and anchored in the plasma membrane via the C-terminal domain. Transcripts encoding this protein are induced in leaf tissue within 8 h of cold treatment and decrease rapidly when plants are returned to normal temperatures. The transcripts are not induced by heat shock, dehydration, exogenous ABA or wounding, whereas transcripts of a control B. napus gene are induced by dehydration and ABA. The possible function of this protein in cold tolerance is discussed.

Abscisic Acid↗
PubMed1988

Hypothermic effects on action potential and force production of hedgehog and guinea pig papillary muscles.

Action potentials and isometric force were recorded in papillary muscles from guinea pigs and summer hedgehogs at different temperatures between 37 and 0 degrees C. The action potential of the hedgehog was of a lower amplitude (mean 83 +/- 6 mV) than that of the guinea pig (mean 110 +/- 5 mV). The action potential duration at 50% repolarization was 22 +/- 2 msec in the hedgehog as compared to 105 +/- 11 msec in the guinea pig. Moreover, there was no distinct plateau phase of the hedgehog action potential. Lowering temperature prolonged the action potential duration in the two preparations by about the same percentage. However, the guinea pig preparation became progressively less excitable below 20 degrees C. Lowered temperature produced a positive inotropic effect in the guinea pig, whereas this effect was very slight in the hedgehog heart. Postextrasystolic potentiation was seen in the guinea pig but not in the hedgehog preparation. It is suggested that this difference between the preparations may be due to a greater relative amount of activator calcium in the hedgehog heart. The difference in cold tolerance between the preparations may reflect a difference in chemical composition of the sarcolemma.

Action Potentials↗
PubMed1991

Temperature effects on the Na and Ca currents in rat and hedgehog ventricular muscle.

Cardiac transmembrane potentials and Na and Ca currents were recorded at different temperatures in rat and hedgehog ventricular muscle. At 35 degrees C in both species resting potential was about -80 mV and upstroke velocity (Vmax) of the action potential above 100 V/s. The shape of the action potential in hedgehog ventricular cells at 35 degrees C was similar to that in the rat showing a fast repolarization phase. When temperature was decreased, the membrane resting potential depolarized and action potential amplitude and Vmax declined. In rat ventricular cells at 10 degrees C, the resting potential was about -40 to -50 mV and Vmax was reduced to about 5 V/s. In hedgehog ventricular cells, however, the transmembrane potentials and Vmax were better maintained at low temperature. Phase 3 of the action potential was markedly prolonged below 20 degrees C in hedgehog but not in rat ventricular cells. When temperature was decreased to 10 degrees C the availability curve of the Na current shifted toward more negative potentials and ICa.peak declined in rat ventricular cells. In hedgehog cardiac preparations, the Na current was less influenced by the cooling and ICa.peak did not change very much at low temperatures. A transient inward current usually considered to induce cardiac arrhythmias could be recorded in rat ventricular cells below 20 degrees C but not in hedgehog preparations. These features of hedgehog cardiac membranes may contribute to the cold tolerance and the resistance to ventricular fibrillation during the hypothermia in mammalian hibernators.

Action Potentials↗
PubMed2005

Factors that influence freezing in the sub-Antarctic springtail Tullbergia antarctica.

Effects of 12 biotic and abiotic factors on the freezing point of the sub-Antarctic springtail, Tullbergia antarctica, were investigated. Repeated cooling of individual springtails five times resulted in very similar freezing points suggesting that ice nucleation in this freeze-susceptible species is likely to be initiated by intrinsic factors rather than being a stochastic event. Mean supercooling point (SCP) was influenced by cooling protocol, showing a linear increase in mean SCP with cooling rates from 8 to 0.1 degrees Cmin(-1). However, the opposite effect (decreasing SCP) was seen with slower cooling. Slower rates may be ecologically realistic and allow time for appropriate physiological and biochemical changes. Feeding and food presence in the gut had no effect on SCP, and there was no correlation between the ice nucleating activity of bacteria isolated from the guts and the whole springtail SCP. Habitat altitude and diurnal light and temperature regimes also had no effect on SCP. There was no correlation between the cryoprotectant concentration of fresh animals and their SCP, but experimental desiccation resulted in increased osmolality and decreased SCP, although with considerable individual variation. The most significant influence on SCP was associated with ecdysis. As springtails cease feeding for a period either side of ecdysis, shedding the entire gut lining, moulting may be an efficient mechanism of clearing the gut of all ice nucleating material. This previously unrecognised relationship between ecdysis, cold tolerance and seasonal survival tactics may play an important role in over-winter survival of some arthropods.

Acclimatization↗
PubMed1989

Health and metabolic responses of young calves housed at -30 degrees C to -8 degrees C.

Newborn, male, Holstein calves, were continuously housed for three weeks in calf hutches at 17 degrees C or in a thermal environment which varied rhythmically on a daily basis either between -20 degrees C and -8 degrees C (experiment A) or between -30 degrees C and -18 degrees C (experiment B). Compared to warm-housed calves, cold-housed calves in experiment A had metabolic rates which were significantly higher (p less than 0.001) in a standing position but which were not significantly different (p less than 0.05) in a recumbent position. Recumbent and standing cold-housed calves in experiment B had an increased (p less than 0.05) metabolic rate compared to warm-housed controls. Heat loss was less (p less than 0.05) for recumbent cold-housed calves in experiment B than for standing calves in a thermoneutral environment. Localized subcutaneous hemorrhages of hindlimbs were a consistent necropsy finding among all cold-housed calves. Average daily gains of cold-housed calves were not significantly different from warm-housed controls. Clinical, physiological and pathological findings indicated that cold treatments used in the present study did not cause serious harm to calves. It was concluded that calves housed in properly managed hutches are remarkably cold tolerant.

Animals↗
PubMed1994

Effect of modafinil on heat production and regulation of body temperatures in cold-exposed humans.

Military personnel often undergo sustained operations that affect vigilance and alertness. Pharmacological agents may be used to enhance vigilance. Most such agents also have thermogenic properties. Whether a new promising stimulant, modafinil (Lyons and French, Aviat. Space Environ. Med. 1991; 62:432-435), has a beneficial effect on cold tolerance in the military context, is not known. The goal of this study was, therefore, to evaluate the effect of this new drug on thermal balance and the regulation of body temperatures in neutral conditions and when challenged by a cold exposure. Nine subjects underwent three trials each: two in the cold (3 h at rest, 10 degrees C) 0.5 h after the ingestion of either placebo or modafinil (200 mg), and one in thermal neutrality with modafinil (same conditions except Tdb = 29.3 degrees C). As expected, cold produced a drop in Tre and Tsk and an increase in Vo2. Although non-significant, there was a tendency for a slightly greater drop in Tre with modafinil (0.65 degrees C vs. 0.57 degrees C with placebo). A similar tendency was found for the heat debt (S) which was greater with modafinil than with placebo (16.1 +/- 0.7 vs. 14.7 +/- 0.6 kJ.kg-1, respectively, +9.5%, p = 0.11). This tendency appears to be the combined result of a slightly lower mean heat production during the test and a slightly greater mean dry heat loss. When tested at thermal neutrality, the drug had no effect on any thermal or metabolic parameters. The results demonstrate that the ingestion of a single dose of modafinil has no significant acute effect on thermal balance in neutral conditions and on thermoregulation in normal subjects exposed to cold. However, a tendency for slightly greater cooling was noted with modafinil. It is not known whether the use of modafinil in conjunction with sleep deprivation (a likely scenario) could magnify this effect.

Adult↗
PubMed2001

Cold urticaria.

Cold urticaria is one form of urticaria that may be associated with other forms of physical urticarias. Frequency is generally estimated at two or three per 100. The triggering effect of cold is found at history taking in most of the cases. The urticaria is usually superficial, and more rarely associated with deep and/or mucosal urticaria. The diagnosis is based on history taking and the ice cube test. An exhaustive search for an etiologic factor is often unfruitful, and the presence of a cryopathy should lead to a complete work-up. Therapy of cold urticaria may prove to be difficult. In patients with secondary cold urticaria, underlying disease must be treated in order to resolve the skin symptoms. H1-antihistamines can be used but the clinical responses are highly variable. Short-time treatment with low concentration corticosteroids suppresses the symptoms only partially and temporarily. In patients who do not respond to previous treatments, induction of cold tolerance may be proposed but the procedure is difficult to carry out in daily life over an extended period. Key word: cryoglobulins.

Adrenal Cortex Hormones↗
PubMed2002

The role of desaturases in cold-induced lipid restructuring.

All organisms respond to environmental challenge by adaptive responses, although, in many cases, the underlying molecular mechanisms are not understood. In the case of membranes, the physical structure of membrane phospholipids is conserved in the face of cold, rigidifying conditions by the elevated proportions of unsaturated fatty acids. We have observed a clear positional specificity in this substitution and head group preferences in carp liver membranes. We have also demonstrated changes in the activity of lipid desaturases that mediate the unsaturation response, caused by both transcriptional and post-translational mechanisms. Another hepatic isoform has recently been discovered with sensitivity, not to cooling, but to dietary variations. Finally, we are testing the importance of desaturase inductions in the inducible cold tolerance of the whole animal.

Animals↗