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PubMed2001

Cold-hardiness of Dermacentor marginatus (Acari: Ixodidae).

The cold-hardiness of Dermacentor marginatus using laboratory-reared offspring of ticks collected in Germany was characterized. Investigations of unfed stages revealed that adult ticks suffered 50% mortality at -10 degrees C after 4-5 months, but larvae and nymphs suffered mortality within few days, whereas -15 degrees C was lethal for all stages within a very short period. Larval hatch and moulting of engorged larvae and nymphs did not occur at < or = 10 degrees C. Embryonic development of eggs with larval hatch was considerably reduced by exposure of eggs to < or = 10 degrees C. Engorged females did not lay eggs at < or = 10 degrees C, the oviposition capability, however, persisted over 6 months at 10 degrees C, 5 months at 5 degrees C, 3 months at 0 degree C and 2 months at -10 degrees C without substantial decrease of the oviposition capacity or reduction of viable eggs. These results present evidence that unfed adult ticks are the ecoepidemiologically most effective stages, which are capable to tolerate long and extremely cold winters without substantial impairment of the population density. It is also considered that engorged females interrupt their oviposition at low and subzero temperatures delaying it for months and so contribute in bypassing winter conditions. None of the stages survived supercooling indicating that D. marginatus is freeze intolerant. Mean supercooling point (SCP) ranged between -26 degrees C in eggs and -12, 6 degrees C in engorged females. Compared with eggs, the SCP of the other stages was significantly higher. In conclusion, the SCP is considered to have no predictive value in the context with cold-hardiness.

Animals↗
PubMed2005

Inertia in physiological traits: Embryonopsis halticella caterpillars (Yponomeutidae) across the Antarctic Polar Frontal Zone.

Geographic variation is characteristic of many physiological traits at the population and species levels. However, several recent studies have suggested that population-level variation is either limited or that it is mostly a consequence of phenotypic plasticity. Here we show that there is considerable physiological inertia in cold hardiness, upper thermal tolerance limits and desiccation resistance in caterpillars of the sub-Antarctic moth Embryonopsis halticella Eaton, such that populations from two climatically different islands are physiologically very similar. Both populations are moderately chill tolerant, with no difference in the supercooling points of caterpillars (-17 to -20 degrees C). Within their host plants caterpillars of both populations freeze at substantially higher, and statistically equivalent temperatures (-9.5 to -11.5 degrees C). The populations also have similar upper lethal limits (38 degrees C), and survival times of dry conditions (6-170 h depending on mass). The previously inexplicably low freezing point of caterpillars at the climatically less severe Marion Island seems likely a consequence of physiological inertia given that the freezing point of caterpillars within their hosts is only a few degrees below absolute minima at the older, and colder, Heard Island. Lack of adaptive geographic variation in physiological traits has consequences for models of range limits, and highlights the importance of exploring phenotypic plasticity as a response to climatic variation.

Animals↗
PubMedDate not supplied

Cold acclimation improves recovery of cryopreserved grass (Zoysia and Lolium sp.).

Cold acclimation of Lolium L. and Zoysia Willd. Grass cultivars significantly increased regrowth of cryopreserved meristems. One wk of cold acclimation improved recovery following cryopreservation but extended acclimation (4-8 wk) resulted in the best regrowth. Cold acclimation also significantly increased the dehydration tolerance of both Zoysia and Lolium meristems. Lolium apices cold acclimated for 4 wk produced 60-100% regrowth following cryopreservation by slow freezing or encapsulation-dehydration. Cold-acclimated Zoysia had greater than 60% regrowth following encapsulation-dehydration when beads were dehydrated to less than 22% water content. Non-acclimated meristems of both genera had little or no regrowth. Thawed meristems grew quickly without callus formation and the plantlets produced were transplanted to pots in the greenhouse after 4 to 6 wk. Samples of each cultivar were stored in liquid nitrogen as part of the U.S. National Plant Germplasm System.

Journal Article↗
PubMed2000

Sensitivity and tolerance to ethanol in mouse lines selected for ethanol-induced hypothermia.

Within-family selective breeding techniques have been used to create two lines of mice to be insensitive (HOT) and two lines to be sensitive (COLD) to the hypothermic effects of an acute 3.0-g/kg ethanol (EtOH) injection. Previous studies have found HOT mice to be relatively resistant to the development of tolerance to this effect, whereas COLD mice readily develop tolerance. The breeding program is currently in selected Generation 52, and the HOT and COLD mice differ by about 10 degrees C (average of both replicates) in their selected hypothermic response. Starting with selection Generation 20, separate lines of mice were inbred from the HOT-2 and COLD-2 selected lines, while selection continued for the original two replicate lines of HOT and COLD mice. To assess whether different dose treatments would produce differential tolerance development in the HOT and COLD selected lines, we administered different dose regimens across 5 days to HOT and COLD mice. The COLD mice developed tolerance while the HOT mice did not, regardless of total EtOH administered. In a separate study, we administered EtOH (3.0 g/kg) to mice for 3 days to assess a shorter tolerance paradigm. We also present here responses to the selection dose of 3.0-g/kg EtOH in the inbred HOT (IHOT-2) and COLD (ICOLD-2) mice tested after 41 generations of brother-sister mating. In addition, we report recent attempts to find doses of EtOH that would produce an equivalent initial hypothermic response in each of the six lines (HOT-1, COLD-1, HOT-2, COLD-2, ICOLD-2, and IHOT-2). When doses were selected to produce similar initial hypothermic sensitivity, tolerance was tested by giving three daily doses and examining the attenuation of the hypothermic response on the third day. All three COLD lines developed significant tolerance, while the HOT lines did not. The HOT and COLD mice provide a genetic model to study mechanisms mediating acute EtOH-induced hypothermia as well as tolerance development.

Animals↗
PubMed1990

Biochemistry of natural freeze tolerance in animals: molecular adaptations and applications to cryopreservation.

For a wide variety of animals, winter survival in cold climates includes the ability to tolerate ice formation in extracellular body fluids. Among terrestrially hibernating vertebrates, freeze tolerance has been documented for five amphibian and two reptile species. These species may survive for days or weeks in a frozen state with no breathing and no heart beat, and with up to 65% of total body water as extracellular ice. The biochemical mechanisms involved in natural freeze tolerance include (i) the regulation of extracellular ice formation by proteinaceous ice nucleators in body fluids, (ii) the accumulation of high concentrations of low molecular weight carbohydrates as cryoprotectants to regulate cell volume reduction during freezing and stabilize macromolecular structure, and (iii) a well-developed ischemia tolerance that supports the survival of individual organs while frozen. The present article focuses on recent advances in our understanding of the biochemistry of natural freeze tolerance in lower vertebrates and the application of these studies to the improvement of cryopreservation technology for transplantable mammalian organs.

Adaptation, Physiological↗
PubMed2003

Molecular genetic perspectives on cross-talk and specificity in abiotic stress signalling in plants.

The perception of abiotic stresses and signal transduction to switch on adaptive responses are critical steps in determining the survival and reproduction of plants exposed to adverse environments. Plants have stress-specific adaptive responses as well as responses which protect the plants from more than one environmental stress. There are multiple stress perception and signalling pathways, some of which are specific, but others may cross-talk at various steps. Recently, progress has been made in identifying components of signalling pathways involved in salt, drought and cold stresses. Genetic analysis has defined the Salt-Overly-Sensitive (SOS) pathway, in which a salt stress-induced calcium signal is probably sensed by the calcium-binding protein SOS3 which then activates the protein kinase SOS2. The SOS3-SOS2 kinase complex regulates the expression and activity of ion transporters such as SOS1 to re-establish cellular ionic homeostasis under salinity. The ICE1 (Inducer of CBF Expression 1)-CBF (C-Repeat Binding Protein) pathway is critical for the regulation of the cold-responsive transcriptome and acquired freezing tolerance, although at present the signalling events that activate the ICE1 transcription factor during cold stress are not known. Both ABA-dependent and -independent signalling pathways appear to be involved in osmotic stress tolerance. Components of mitogen-activated protein kinase (MAPK) cascades may act as converging points of multiple abiotic as well as biotic stress signalling pathways. Forward and reverse genetic analysis in combination with expression profiling will continue to uncover many signalling components, and biochemical characterization of the signalling complexes will be required to determine specificity and cross-talk in abiotic stress signalling pathways.

Abscisic Acid↗
PubMed1992

Matching pain coping strategies to the individual: a prospective validation of the cognitive coping strategy inventory.

The validity of the Cognitive Coping Strategy Inventory (CCSI; Butler et al., 1989) was tested in a prospective fashion. Subjects were randomly assigned to one of three conditions. Some were "matched" to a strategy for which they received a high CCSI score, some were "mismatched" to a strategy for which they received a low CCSI score, and some were given a choice of strategies. Those subjects using a matched strategy obtained better threshold and tolerance times on the cold pressor than subjects who used a mismatched strategy. Despite clear differences in exposure to the cold pressor these conditions did not differ from each other in self-reported levels of pain. It was concluded that the CCSI appears to be a valid and useful tool for selecting a coping strategy to help particular individuals manage acute pain. Though the CCSI is relatively easy to administer and score, the comparative costs and benefits of using it must be weighed against the somewhat more efficient approach of simply offering the subject a choice of treatments. Subjects given a choice of strategies performed as well as subjects matched to a strategy on the basis of CCSI scores.

Adaptation, Psychological↗
PubMed1999

Carbohydrate content and metabolism as related to maturity and chilling sensitivity of cv. Fortune mandarins.

Fruits of cv. Fortune mandarin were periodically harvested throughout the ripening period to evaluate changes in carbohydrate content and metabolism in flavedo tissue and to determine the potential role of carbohydrates in the tolerance of citrus fruit to chilling injury (CI). Sucrose showed little change in the flavedo during the season, but fructose and glucose increased, in nearly equal amounts, throughout the fall and winter, reaching a maximum in January. Starch levels were less abundant than soluble carbohydrates and rose continuously until March. Sucrose phosphate synthase (SPS; EC 4.1.14) activity decreased from December throughout ripening. Changes in sucrose synthase (SS; EC 2.4.1.13) and acid and alkaline invertase (Inv; EC 3.2.1.26) activities correlated with changes in the reducing sugars, but acid invertase was less active than the other sucrose-metabolizing enzymes. Carbohydrate changes in the flavedo of Fortune mandarins with fruit maturity appear not to be related to the chilling tolerance of fruits during cold storage.

Carbohydrate Metabolism↗
PubMed2005

Longer lifespan, altered metabolism, and stress resistance in Drosophila from ablation of cells making insulin-like ligands.

The insulin/insulin-like growth factor-like signaling pathway, present in all multicellular organisms, regulates diverse functions including growth, development, fecundity, metabolic homeostasis, and lifespan. In flies, ligands of the insulin/insulin-like growth factor-like signaling pathway, the Drosophila insulin-like peptides, regulate growth and hemolymph carbohydrate homeostasis during development and are expressed in a stage- and tissue-specific manner. Here, we show that ablation of Drosophila insulin-like peptide-producing median neurosecretory cells in the brain leads to increased fasting glucose levels in the hemolymph of adults similar to that found in diabetic mammals. They also exhibit increased storage of lipid and carbohydrate, reduced fecundity, and reduced tolerance of heat and cold. However, the ablated flies show an extension of median and maximal lifespan and increased resistance to oxidative stress and starvation.

Animals↗
PubMed1995

Effects of cold storage and water stress on water relations and gas exchange of white spruce (Picea glauca) seedlings.

To determine the effects of lifting time and storage on water-stress resistance of nursery-grown white spruce (Picea glauca (Moench) Voss) seedlings, we compared gas exchange, water relations and mortality of 3-year-old seedlings lifted in October 1991 and stored at -2 degrees C for 3 months with seedlings lifted in January 1992. The seedlings were placed in nutrient solution and subjected to -1.1 or -2.7 MPa water stress induced by polyethylene glycol 3350 for 9 days. Water stress, but not lifting time, had a significant effect on seedling net assimilation, symplastic volume and turgor loss point. In a second experiment, seedlings lifted in October 1991 were stored at -2 degrees C for 7 months and compared with seedlings lifted in May 1992. The seedlings were planted in pots, and their gas exchange and water relation parameters measured in response to gradual water stress. The results suggest that prolonged cold storage retards photosynthetic recovery of seedlings after planting. Higher rates of net assimilation in seedlings lifted in May were not directly related to their water status. Nonstomatal limitations were the primary factor influencing photosynthetic rate. We conclude that the inferior ability of cold-stored seedlings to tolerate water stress was due to poor osmotic adjustment and a lag in recovery of photosynthesis.

Journal Article↗
PubMed2004

Exploring the temperature-stress metabolome of Arabidopsis.

Metabolic profiling analyses were performed to determine metabolite temporal dynamics associated with the induction of acquired thermotolerance in response to heat shock and acquired freezing tolerance in response to cold shock. Low-M(r) polar metabolite analyses were performed using gas chromatography-mass spectrometry. Eighty-one identified metabolites and 416 unidentified mass spectral tags, characterized by retention time indices and specific mass fragments, were monitored. Cold shock influenced metabolism far more profoundly than heat shock. The steady-state pool sizes of 143 and 311 metabolites or mass spectral tags were altered in response to heat and cold shock, respectively. Comparison of heat- and cold-shock response patterns revealed that the majority of heat-shock responses were shared with cold-shock responses, a previously unknown relationship. Coordinate increases in the pool sizes of amino acids derived from pyruvate and oxaloacetate, polyamine precursors, and compatible solutes were observed during both heat and cold shock. In addition, many of the metabolites that showed increases in response to both heat and cold shock in this study were previously unlinked with temperature stress. This investigation provides new insight into the mechanisms of plant adaptation to thermal stress at the metabolite level, reveals relationships between heat- and cold-shock responses, and highlights the roles of known signaling molecules and protectants.

Acclimatization↗
PubMed2006

Glycinebetaine counteracts the inhibitory effects of salt stress on the degradation and synthesis of D1 protein during photoinhibition in Synechococcus sp. PCC 7942.

Glycinebetaine (hereafter referred to as betaine) is a compatible solute that accumulates in certain plants and microorganisms in response to various types of stress. We demonstrated previously that when the cyanobacterium Synechococcus sp. PCC 7942 (hereafter Synechococcus) is transformed with the codA gene for choline oxidase, it can synthesize betaine from exogenously supplied choline, exhibiting enhanced tolerance to salt and cold stress. In this study, we examined the effects of salt stress and betaine synthesis on the photoinhibition of photosystem II (PSII). Salt stress due to 220 mm NaCl enhanced photoinhibition of PSII and betaine protected PSII against photoinhibition under these conditions. However, neither salt stress nor betaine synthesis affected photodamage to PSII. By contrast, salt stress inhibited repair of photodamaged PSII and betaine reversed this inhibitory effect of salt stress. Pulse-chase-labeling experiments revealed that salt stress inhibited degradation of D1 protein in photodamaged PSII and de novo synthesis of D1. By contrast, betaine protected the machinery required for degradation and synthesis of D1 under salt stress. Neither salt stress nor betaine affected levels of psbA transcripts. These observations suggest that betaine counteracts the inhibitory effects of salt stress, with resultant accelerated repair of photodamaged PSII.

Betaine↗
PubMed2006

Molecular cloning, characterization and expression of a novel trehalose-6-phosphate synthase homologue from Ginkgo biloba.

In many organisms, trehalose acts as protective metabolite against harsh environmental stresses, such as freezing, drought, nutrient starvation, heat and salt. Herein a cDNA (designated as GbTPS, GenBank Accession Number AY884150) encoding a trehalose-6-phosphate synthase homologue was isolated and characterized from the living fossil plant, Ginkgo biloba, which is highly tolerant to drought and cold. GbTPS encoded an 868-amino-acid polypeptide with a predicted isoelectric point of 5.83 and molecular mass of 97.9 kD. Amino acid sequence alignment revealed that GbTPS shared high identity with class II trehalose-6-phosphate synthase homologues (67% identical to AtTPS7), but had only 17% and 23% of identity with OstA from Escherichia coli and ScTPS1 from S. cerevisiae, respectively. DNA gel blot analysis indicated that GbTPS belonged to a small multi-gene family. The expression analysis by RT-PCR showed that GbTPS expressed in a tissue-specific manner in G. biloba and might involve in leaf development. GbTPS was also found to be induced by a variety of stresses including cold, salt, drought and mannitol.

Amino Acid Sequence↗
PubMedDate not supplied

Hepatic resection under in situ hypothermic hepatic perfusion.

BACKGROUND/AIMS: Temporary inflow occlusion of the portal triad has been used frequently in hepatectomy to minimize bleeding. On the other hand, Pringle's maneuver produces ischemic-reperfusion injury especially in patients with underlying liver disease. METHODOLOGY: Thirty-seven cases of hepatic resections were performed with intermittent Pringle's maneuver (IP group; n = 17) and in situ hypothermic perfusion (CP group; n = 20). In the CP group, hepatic inflow was continuously occluded, and 4-degree Centigrade Ringer's lactate was administered by drip during resection. Hepatic outflow occlusion was not performed. RESULTS: All patients tolerated the procedures well. Cold perfusion technique significantly decreased both the times required and the blood loss in hepatectomy (p < 0.05). Serum hyaluronic acid levels gradually increased after the induction of hepatectomy and peaked 10 minutes after reperfusion in the both groups. Thereafter, it decreased and showed a significantly lower level in the CP group until 60 minutes after reperfusion (p < 0.05). Hepaplastin levels remained significantly higher in the CP group one week after operation (p < 0.05). CONCLUSIONS: Using the technique of in situ hypothermic perfusion, we can prolong the ischemic time safely with minimal systemic influence even in cases with underlying liver diseases. This may compare favorably with intermittent Pringle's maneuver in terms of reducing hepatic sinusoidal endothelial cell damage during hepatectomy and reperfusion.

Adult↗
PubMed1996

Aortic valve replacement: better myocardial protection by cold or warm retrograde blood cardioplegia?

BACKGROUND AND AIMS OF THE STUDY: To determine whether warm blood cardioplegia (BCP) is superior to cold BCP in terms of myocardial protection, we compared warm (37 degrees C) and cold (4 degrees C) continuous retrograde administration of BCP in 40 patients undergoing aortic valve replacement (AVR) in a prospective, randomized study. MATERIALS AND METHODS: The main subjects of investigation were the myocardial oxygen consumption and the maintenance of the ultrastructure of the tissue. In addition, we looked at intraoperative recordings of time, heart rhythm disturbances, CK/MB serum levels, and inotropic support. RESULTS: We found, that oxygen consumption is significantly higher during warm BCP (7.95-10.38 ml/min) than during cold BCP (2.11-3.47 ml/min). Mild, reversible myocardial damage occurs during cold and warm BCP. The intraoperative serum potassium level was significantly higher after warm (7.25 mmol/l) than after cold (6.55 mmol/l) BCP. There was no statistically significant difference in the duration of extracorporeal circulation and of cardiac arrest, the CK/MB serum level or the recorded right and left ventricular performance data in the two groups. CONCLUSIONS: We conclude that continuous retrograde warm BCP is not superior to continuous retrograde cold BCP as far as myocardial protection is concerned. The administration of cold BCP prolongs the tolerated ischemic time of the myocardium and provides a higher safety margin.

Adult↗
PubMed2002

Arabidopsis transcriptome profiling indicates that multiple regulatory pathways are activated during cold acclimation in addition to the CBF cold response pathway.

Many plants, including Arabidopsis, increase in freezing tolerance in response to low, nonfreezing temperatures, a phenomenon known as cold acclimation. Previous studies established that cold acclimation involves rapid expression of the CBF transcriptional activators (also known as DREB1 proteins) in response to low temperature followed by induction of the CBF regulon (CBF-targeted genes), which contributes to an increase in freezing tolerance. Here, we present the results of transcriptome-profiling experiments indicating the existence of multiple low-temperature regulatory pathways in addition to the CBF cold response pathway. The transcript levels of approximately 8000 genes were determined at multiple times after plants were transferred from warm to cold temperature and in warm-grown plants that constitutively expressed CBF1, CBF2, or CBF3. A total of 306 genes were identified as being cold responsive, with transcripts for 218 genes increasing and those for 88 genes decreasing threefold or more at one or more time points during the 7-day experiment. These results indicate that extensive downregulation of gene expression occurs during cold acclimation. Of the cold-responsive genes, 48 encode known or putative transcription factors. Two of these, RAP2.1 and RAP2.6, were activated by CBF expression and thus presumably control subregulons of the CBF regulon. Transcriptome comparisons indicated that only 12% of the cold-responsive genes are certain members of the CBF regulon. Moreover, at least 28% of the cold-responsive genes were not regulated by the CBF transcription factors, including 15 encoding known or putative transcription factors, indicating that these cold-responsive genes are members of different low-temperature regulons. Significantly, CBF expression at warm temperatures repressed the expression of eight genes that also were downregulated by low temperature, indicating that in addition to gene induction, gene repression is likely to play an integral role in cold acclimation.

Acclimatization↗
PubMed2003

Development of antinociceptive tolerance and changes of opioid receptor ligand binding in central nervous system of the mouse forced to single and repeated swimming in the cold water.

The present study was designed to characterize underlying mechanism involved in the development of tolerance in the production of antinociceptive effect induced by repeated cold water swimming stress (CWSS) using the tail-flick test. Mice were forced to swim at 4 degrees C for 3min and the tail-flick test was performed 5, 10, 20, and 30min after the swimming. The profound antinociception was induced by a single CWSS. However, when the mice were exposed to CWSS repeatedly seven times, they showed a tolerance in the production of antinociception. In the opioid receptor binding study, Bmax of delta opioid receptor (DOR) was decreased in the brainstem, midbrain and the spinal cord areas by both a single and repeated CWSS, without altering Kd value. However, Bmax values of mu opioid receptor (MOR) and kappa opioid receptor (KOR) were increased in the brainstem, midbrain and spinal cord regions by repeated CWSS, without changing Kd values. Our results suggest that the development of tolerance in the production of antinociception in mice forced to the repeated CWSS may be, at least, due to the reduction of DOR number in the brainstem, midbrain and the spinal cord regions.

Analgesics↗
PubMed1998

Reduced anti-allodynic effect of the adenosine A1-receptor agonist R-phenylisopropyladenosine on repeated intrathecal administration and lack of cross-tolerance with morphine in a rat model of central pain.

UNLABELLED: We examined the development of tolerance to the antiallodynic effect of chronic intrathecal (IT) administration of the adenosine analog R-phenylisopropyladenosine (R-PIA) in a rat model of central pain after ischemic spinal cord injury. After 10 days of IT R-PIA treatment, the effect of IT morphine was also assessed to examine whether cross-tolerance between R-PIA and morphine was present. IT R-PIA completely alleviated allodynia-like behaviors to mechanical and cold stimuli in spinally injured rats. The anti-allodynic effect of R-PIA was maintained for 6-7 days with twice-daily administration and was reduced thereafter, particularly with respect to cold allodynia. IT morphine alleviated mechanical and cold allodynia in rats rendered tolerant to R-PIA to a degree comparable to that in R-PIA-naive (control) rats, which indicates that the anti-allodynic property of R-PIA is independent of the mechanisms by which morphine acts. The possibility of using agonists of adenosine receptors in treating refractory pain in patients with spinal cord injury is discussed. IMPLICATIONS: There is often no satisfactory treatment for chronic pain after spinal cord injury. Our study suggests such pain can be treated with a spinal injection of R-phenylisopropyladenosine in rats. Reduced effect to R-phenylisopropyladenosine was noted with repeated administrations. However, there was no cross-tolerance to morphine.

Adenosine↗