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At least 649 records · Page 36Linked to original sources
PubMed2003

ICE1: a regulator of cold-induced transcriptome and freezing tolerance in Arabidopsis.

Cold temperatures trigger the expression of the CBF family of transcription factors, which in turn activate many downstream genes that confer chilling and freezing tolerance to plants. We report here the identification of ICE1 (inducer of CBF expression 1), an upstream transcription factor that regulates the transcription of CBF genes in the cold. An Arabidopsis ice1 mutant was isolated in a screen for mutations that impair cold-induced transcription of a CBF3 promoter-luciferase reporter gene. The ice1 mutation blocks the expression of CBF3 and decreases the expression of many genes downstream of CBFs, which leads to a significant reduction in plant chilling and freezing tolerance. ICE1 encodes a MYC-like bHLH transcriptional activator. ICE1 binds specifically to the MYC recognition sequences in the CBF3 promoter. ICE1 is expressed constitutively, and its overexpression in wild-type plants enhances the expression of the CBF regulon in the cold and improves freezing tolerance of the transgenic plants.

Acclimatization↗
PubMed1995

Influence of the sympathetic nervous system in the development of abnormal pain-related behaviours in a rat model of neuropathic pain.

This study evaluated the effect of surgical sympathectomy on pain-related behaviours in a well established model of peripheral mononeuropathy produced by loose ligatures around the common sciatic nerve in the rat. Behavioural abnormalities include spontaneous abnormal position of the hindpaw after the nerve constriction, indicative of "spontaneous pain", and changes in responses to mechanical or thermal stimuli applied to this paw. These changes are usually maximal at week 2 after the surgery, stable until weeks 3-4, and disappear between weeks 8 and 12. To assess the role of the sympathetic nervous system in the development and persistence of these abnormalities, four groups of rats were behaviourally tested: (i) rats receiving a complete sham surgery, (ii) rats with a sciatic nerve constriction produced by loose ligatures around the common nerve trunk plus a sham sympathectomy, (iii) rats receiving a lumbar sympathectomy with a sham nerve ligature, and (iv) rats receiving a simultaneous surgical lumbar sympathectomy and a sciatic nerve constriction. The efficacy of the sympathectomy was assessed by the measure of the noradrenaline level in the sciatic nerve. Sympathectomy reduced selectively or even prevented the abnormal reaction to cold temperature and to heat (45 degrees C) in rats with a peripheral mononeuropathy. In contrast, the abnormal reaction to mechanical pressure was not influenced, and the behavioural abnormalities indicating spontaneous pain were still present. Sympathectomy alone resulted in a reduction of the vocalization threshold to pressure on both hindpaws, but also a short-lasting increased tolerance to cold immersion. This study confirms the selective role of the sympathetic nervous system in affecting the development and maintenance of some abnormal pain-related behaviours to thermal stimuli in rats with a moderate, but persistent, constriction of one sciatic nerve.

Animals↗
PubMed1995

Hypothermia-related deaths--New Mexico, October 1993-March 1994.

Hypothermia is an unintentional lowering of the body temperature to < or = 95 F (< or = 35 C) (1). From 1979 through 1992, 10,550 persons in the United States died from hypothermia, an average of 754 deaths per year (range: 557-1021). Most of these deaths occurred during winter months in three distinct climatic areas: northern states characterized by moderate to severe cold temperatures during winter (e.g., Illinois and New York); southern states where rapid changes in temperature occur because of the effects of weather systems (e.g., North Carolina, South Carolina, and Virginia); and western states in areas of high elevations and profound declines in temperatures at night (e.g., New Mexico and Arizona). From October 1993 through March 1994, a total of 23 deaths attributed to hypothermia were reported to the New Mexico Office of the Medical Investigator. This report summarizes the investigations of four of these deaths and the epidemiology for all 23 cases.

Adult↗
PubMed1988

Pigment adherence as a measure of retinal adhesion: dependence on temperature.

Retinal adhesion deteriorates rapidly after enucleation. We have developed a new in vitro method for measuring retinal adhesiveness in the rabbit that is faster than previous models, and can monitor changes sooner after enucleation. We used the percentage of retina which retained pigment after peeling from the RPE as a quantitative measure of retinal adhesiveness. We found that the failure of adhesion after death is more rapid and severe than previously reported, but can be inhibited by cold temperature. Pigment adherence was also modified by ionic and metabolic factors that have been found to affect other indices of adhesion. These results emphasize the limitations of in vitro data relative to the physiologic forces that maintain retinal adhesion in vivo.

Acetazolamide↗
PubMed2004

Seasonal temperature compensation in the horse mussel, Modiolus modiolus: metabolic enzymes, oxidative stress and heat shock proteins.

Seasonal collections of the subtidal horse mussel, Modiolus modiolus, from a depth of 10 m were made at the Isles of Shoals, New Hampshire to assess changes in overall energetic demand, measured as respiration, the maximal activities of rate-limiting enzymes of intermediate metabolism, level of oxidative stress, and the expression of heat shock proteins (HSP). Weighted respiration rates of mussels from winter collections were significantly lower than summer rates but decreased by less than 20%. Specific activities of several rate-limiting enzymes were measured in mussels from the summer and winter collections at the temperature of collection and the reciprocal seasonal temperature (15 and 5 degrees C). Comparisons of these enzyme activities and the protein concentrations of hexokinase and citrate synthase show that a quantitative strategy is used to acclimatize to winter temperatures by these rate-limiting enzymes of intermediate metabolism. The activities and protein concentrations of the antioxidant enzyme, Cu/Zn superoxide dismutase (SOD) is seasonally indistinguishable while the concentration of HSP 70 was greater in winter than in summer samples. These results show that mussels seasonally compensate for decreases in temperature by increasing the concentration of rate-limiting metabolic enzymes while maintaining the same level of antioxidant protection in summer and winter consistent with high aerobic metabolism in both winter and summer. Lastly, the significantly greater concentrations of HSP70 in winter samples suggests that protein chaperone functions must be maintained while other seasonal adjustments to cold temperatures are occurring.

Adaptation, Physiological↗
PubMed1995

Cold-Specific Induction of a Dehydrin Gene Family Member in Barley.

An interval on barley (Hordeum vulgare L.) chromosome 7 accounting for significant quantitative trait locus effects for winter hardiness were detected in a winter (Dicktoo) x spring (Morex) barley population (P.M. Hayes, T. Blake, T.H.H. Chen, S. Tragoonrung, F. Chen, A. Pan, and B. Liu [1993] Genome 36: 66-71). Two members of the barley dehydrin gene family, Dhn1 and Dhn2, were located within the region defining the winter hardiness quantitative trait locus effect (A. Pan, P.M. Hayes, F. Chen, T. Blake, T.H.H. Chen, T.T.S. Wright, I. Karsai, Z. Bedo [1994] Theor Appl Genet 89: 900-910). To investigate the possible role of Dhn1 and Dhn2 in winter hardiness, we examined the expression pattern of six barley dehydrin gene family members in shoot tissue in response to cold temperature. Incubation of 3-week-old barley plants at 2[deg]C resulted in a rapid induction of a single 86-kD polypeptide that was recognized by an antiserum against a peptide conserved in the dehydrin gene family. Northern blot analysis confirmed the induction of an mRNA corresponding to Dhn5. The expression patterns of cold-induced dehydrins in shoot tissue for Dicktoo and Morex were identical under the conditions studied, in spite of the known phenotypic differences in their winter hardiness. These results, together with the allelic structure of selected high- and low-survival lines, suggest that the Dicktoo alleles at the Dhn1 and Dhn2 may not be the primary determinants of winter hardiness in barley.

Journal Article↗
PubMed1996

lem7, a novel temperature-sensitive Arabidopsis mutation that reversibly inhibits vegetative development.

An important question in developmental biology concerns the mechanisms by which a few cells coordinate division and differentiation to yield the complex structures and organs found in multicellular organisms. During vegetative growth in plants, cells in the apical meristem must coordinate division and differentiation to yield the fully mature leaf organ. Alterations in these processes may result in an abnormal leaf. In this paper we present the isolation and characterization of an EMS-generated, cold-temperature-sensitive mutation in Arabidopsis thaliana, designated lem7 (leaf morphogenesis). lem7 is a semidominant mutation that maps to a novel locus on chromosome 2. When grown at 16 degrees C, lem7 reversibly arrests leaf development at the shoot apex. In contrast, lem7 grown at 30 degrees C appears phenotypically normal. Our data also suggest that the Lem7 locus may not be involved solely in leaf organogenesis, but may also play a role in floral development and the maintenance of patterns and structures after cellular differentiation. At an intermediate temperature of 23 degrees C, leaves on the lem7 plant emerged phenotypically normal but began to show drastic changes at about 13 days postgermination. These changes include a reduced bilateral symmetry, a rough leaf lamina, a reduced number of trichomes, and an altered vascular network. Leaves that developed at the permissive temperature (30 degrees C) and shifted to the nonpermissive temperature (16 degrees C) form tumor-like outgrowths. Histological analysis of these tumor-like outgrowths and leaves grown at the intermediate temperature reveal abnormally large mesophyll cells, a disorganized mesophyll layer, and collapsed epidermal cells. We propose that the reversible inhibition of leaf development in lem7 under nonpermissive temperatures may serve as a useful tool for identifying genes involved in Arabidopsis leaf organogenesis.

Arabidopsis↗
PubMed1971

Temperature Physiology of the Sea Snake Pelamis platurus: An Index of Its Colonization Potential in the Atlantic Ocean.

The yellow-bellied sea snake Pelamis platurus occurs throughout the tropical Indian and Pacific Oceans from east Africa to Central America. Its latitudinal distribution limits coincide with the 18 degrees C surface isotherm. P. platurus has upper and lower thermal tolerances of 36.0 and 11.7 degrees C. With rapid cooling, P. platurus stops feeding at 16-18 degrees C; however, it has a high resistance to cold temperature and can withstand 5 degrees C for 1 hr. After 10 days' exposure, P. platurus does not acclimate to 17 degrees C and, thus, would not be able to survive for long periods in water this cold.In the event of its transit through the proposed Central American Sea-Level Canal, P. platurus would colonize the Atlantic Ocean and, during the summer months, would be able to extend its north Atlantic distribution to as far as Cape Cod and the English Channel.

Journal Article↗
PubMed1977

Neurofilamentous changes in goldfish (Carassius auratus L.) brain in relation to environmental temperature.

The presence of neurofilaments in the synaptic boutons in the brains of goldfish maintained at 5 degrees C for 177 days or more is reported. Neurofilaments are not found in boutons of control fish kept at 15degreesC. It is suggested that the neurofilaments may be equated with neurofibrillary rings seen by light microscopy. Neurofilaments have been implicated in axoplasmic transport and, therefore, irregularities in the occurrence or appearance of these filaments may reflect alterations in their functions. The unusual occurrence of neurofilaments in the boutons of cold temperature goldfish may be an expression of early degenerative changes or may represent a modification of axoplasmic transport. The suitability of goldfish as a model for the study of the functional effects of neurofibrillary/neurofilamentous accumulations is discussed.

Animals↗
PubMed2005

A cluster of 11 CBF transcription factors is located at the frost tolerance locus Fr-Am2 in Triticum monococcum.

Due to the adverse effects of cold temperatures on winter wheat, frost tolerance is an important trait for breeding programs in regions with severe winters. Frost tolerance locus Fr-A(m)2 was recently discovered in diploid wheat (Triticum monococcum L.). This locus was mapped as a QTL on chromosome 5A(m) in the same region as a QTL for the level of transcription of the cold-regulated gene COR14b at 15 degrees C. A CBF transcription factor was mapped in the center of these two overlapping QTLs. However, since the CBF gene family in wheat has numerous members, it was possible that multiple CBF genes were present at Fr-A(m)2. To investigate this possibility we initiated a systematic characterization of the CBF family in T. monococcum. Here we report the molecular characterization of thirteen TmCBF genes. Nine of them were numbered according to the closest barley HvCBF gene, and the other four that have no clear barley orthologues were assigned numbers TmCBF15 to TmCBF18. TmCBF5 and TmCBF18 were mapped on T. monococcum chromosomes 7A(m) and 6A(m), respectively, and are thus not candidates for the Fr-A(m)2 gene. The remaining eleven TmCBF genes are clustered at the Fr-A(m)2 locus within five different Bacterial Artificial Chromosome (BAC) clones. These BACs were mapped using a high-density map and recombination events were found between most BACs. Lines carrying these recombination events will be useful to identify which of the CBF genes is responsible for the differences in frost tolerance between the T. monococcum parental lines at the Fr-A(m)2 locus.

Acclimatization↗
PubMed1988

Time course of thermal adaptation in plasma membranes of trout kidney. I. Headgroup composition.

The phospholipid composition of plasma membranes from the kidney of rainbow trout, Salmo gairdneri, was determined over a period of 21 days as fish were acclimating between temperatures of 5 and 20 degrees C. Proportions of phosphatidylethanolamine (PE) were significantly higher (29.03 vs. 23.26%) in membranes of 5 degrees C- than 20 degrees C-acclimated trout, whereas levels of phosphatidylcholine (PC) were similar. During acclimation, changes in headgroup composition were restricted primarily to PE and PC, with proportions of the former increasing and the latter decreasing on cold exposure. Headgroup composition changed rapidly as indicated by variations in PC/PE, which dropped from 1.71 +/- 0.13 to 0.78 +/- 0.11 within 8 h of cold acclimation and rose from 1.31 +/- 0.15 to 2.0 +/- 0.13 by the 2nd day of warm acclimation. Differences between warm- and cold-acclimating fish in the proportion of both PC and PE attained during the acclimation time course exceeded the magnitude of the differences between fully acclimated fish. Because of differences in molecular geometry and physical properties between PC and PE, the observed changes in headgroup composition may result in thermal compensation of membrane function, and the more rapid response to cold as opposed to warm stress suggests a primary role in adaptation to cold temperatures. However, headgroup modulation is most likely to contribute to homeoviscous adaptation only during the initial stages of the acclimatory response.

5'-Nucleotidase↗
PubMed2006

248 nm photolysis of CH2Br2 by using cavity ring-down absorption spectroscopy: Br2 molecular elimination at room temperature.

Following photodissociation of CH2Br2 at 248 nm, Br2 molecular elimination is detected by using a tunable laser beam, as crossed perpendicular to the photolyzing laser beam in a ring-down cell, probing the Br2 fragment in the B 3Piou+ -X 1Sigmag+ transition. The nascent vibrational population is obtained, yielding a population ratio of Br2(v = 1)Br2(v = 0) to be 0.7 +/- 0.2. The quantum yield for the Br2 elimination reaction is determined to be 0.2 +/- 0.1. Nevertheless, when CH2Br2 is prepared in a supersonic molecular beam under cold temperature, photofragmentation gives no Br2 detectable in a time-of-flight mass spectrometer. With the aid of ab initio potential energy calculations, a plausible pathway is proposed. Upon excitation to the 1B1 or 3B1 state, C-Br bond elongation may change the molecular symmetry of Cs and enhance the resultant 1 1,3A'-X 1A' (or 1 1,3B1-X 1A1 as C2v is used) coupling to facilitate the process of internal conversion, followed by asynchronous concerted photodissociation. Temperature dependence measurements lend support to the proposed pathway.

Journal Article↗
PubMed1990

Cultured Chinese hamster cells undergo apoptosis after exposure to cold but nonfreezing temperatures.

Cultured Chinese hamster V79 fibroblast cells at the transition from logarithmic to stationary growth have been shown to undergo apoptosis (programmed cell death) after cold shock [B. L. Soloff, W. A. Nagle, A. J. Moss, Jr., K. J. Henle, and J. T. Crawford, Biochem. Biophys. Res. Commun. 145, 876-883 (1987)]. In this report, we show that about 95% of the cell population was susceptible to cold-induced apoptosis, and the amount of cell killing was dependent on the duration of hypothermia. Cells treated for 0-90 min at 0 degrees C exhibited an exponential survival curve with a D0 of 32 min; thus, even short exposures to the cold (e.g., 5 min) produced measurable cell killing. The cold-induced injury was not produced by freezing, because similar results were observed at 6 degrees C, and cell killing was not influenced by the cryoprotective agent dimethyl sulfoxide. Cold-induced apoptosis was inhibited by rewarming at 23 degrees C, compared to 37 degrees C, by inhibitors of macromolecular synthesis, such as cycloheximide, and by 0.8 mM zinc sulfate. The results suggest that apoptosis represents a new manifestation of cell injury after brief exposure to 0-6 degrees C hypothermia.

Animals↗