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At least 307 records · Page 17Linked to original sources
PubMed2005

Satellite tagging and cardiac physiology reveal niche expansion in salmon sharks.

Shark populations are declining globally, yet the movements and habitats of most species are unknown. We used a satellite tag attached to the dorsal fin to track salmon sharks (Lamna ditropis) for up to 3.2 years. Here we show that salmon sharks have a subarctic-to-subtropical niche, ranging from 2 degrees to 24 degrees C, and they spend winter periods in waters as cold as 2 degrees to 8 degrees C. Functional assays and protein gels reveal that the expression of excitation-contraction coupling proteins is enhanced in salmon shark hearts, which may underlie the shark's ability to maintain heart function at cold temperatures and their niche expansion into subarctic seas.

Acclimatization↗
PubMed2002

Interactive effects of nitrogen and irradiance on sustained xanthophyll cycle engagement in Eucalyptus nitens leaves during winter.

Eucalyptus nitens is a species that is adapted to low temperature. This study examines xanthophyll-cycle engagement in E. nitens seedlings exposed to cold-induced photoinhibitory conditions under different levels of irradiance and nutrient status. Xanthophyll-cycle pool size indicated an increased requirement for light energy dissipation under high irradiance and low nutrient status. Greater sensitivity to photoinhibition of non-shaded seedlings indicated that sustained xanthophyll-cycle engagement may occur in response to damaged chlorophyll. Within irradiance treatments, fertilised seedlings had higher photochemical efficiency and faster recovery from photoinhibition than unfertilised seedlings. These results demonstrate that fertilised compared to unfertilised seedlings can utilise a greater proportion of incident light under cold temperature conditions

Cold Temperature↗
PubMed2004

Temperature-sensitive defects in paramyotonia congenita mutants R1448C and T1313M.

The biophysical origins of paramyotonia congenita and its exacerbation in cold temperatures were examined. Human skeletal muscle voltage-gated sodium channels were expressed in Xenopus oocytes and macroscopic currents were recorded from cell-attached patches. Wild-type (hNaV1.4) channels were compared to two mutant channel isoforms, T1313M and R1448C. The voltage dependence and temperature sensitivity of activation, fast-inactivation onset and recovery, and deactivation were studied. Although activation and the onset of fast-inactivation were temperature sensitive in all three isoforms, and although these properties in mutant channels differed from those in wild-type channels, they did not account for cold-exacerbation. Deactivation, however, was disproportionately slower in R1448C, but not in T1313M, than in hNaV1.4. These defects may, at least in part, account for the clinical symptoms of paramyotonia congenita and its exacerbation by cold, and provide a basis for studies into the therapeutic alleviation of these symptoms.

Animals↗
PubMed2006

Endoglucanase-producing fungi isolated from Cape Evans historic expedition hut on Ross Island, Antarctica.

Early explorers of Antarctica's Heroic Era erected wooden buildings and brought large quantities of supplies to survive in Antarctica. The introduction of wood and other organic materials provided nutrient sources for fungi that were indigenous to Antarctica or were brought in with the materials and adapted to the harsh conditions. Seventy-two isolates of filamentous fungi were cultured on selective media from interior structural wood of the Cape Evans historic hut and 27 of these screened positive for the ability to degrade carboxymethyl cellulose (CMC). Four non-CMC-degrading isolates were added to a group of 14 CMC-degrading isolates for further study, and endo-1, 4-beta-glucanase activity was demonstrated in the extracellular supernatant from all of these 18 isolates when grown at 4 degrees C, and also when they were grown at 15 degrees C. Isolates of Penicillium roquefortii and Cadophora malorum showed preference for growth at 15 degrees C rather than 25 degrees C or 4 degrees C indicating psychrotrophic characteristics. These results demonstrate that cellulolytic filamentous fungi found in Antarctica are capable of growth at cold temperatures and possess the ability to produce extracellular endo-1, 4-beta-glucanase when cultured at cold and temperate temperatures.

Antarctic Regions↗
PubMed2006

Monitoring temperatures in the vaccine cold chain in Bolivia.

This study monitored vaccine cold chain temperatures during routine DTP-HB-Hib vaccine shipments from central stores to 11 communities in 3 provinces of Bolivia. In all 11 monitored shipments, vaccines were exposed to freezing temperatures at one or more points. In each of the shipments, temperatures below 0 degrees C were recorded for 2-50% of the monitoring period. Freezing occurred at almost every level of the cold chain distribution system, especially during district and health center storage and during transport to the province and district levels. Seven of the 11 shipments were exposed to temperatures above 8 degrees C, although none were exposed to excessive heat longer than 1.3% of the total monitoring period.

Bolivia↗
PubMed1974

Studies on derivation of transcobalamin 3 from granulocytes. Enhancement by lithium and elimination by fluoride of in vitro increments in vitamin B12-binding capacity.

Unsaturated vitamin B(12)-binding capacity (UBBC) of human serum is not reproducibly measurable because it increases variably in vitro in relation to time, temperature, and, in the case of plasma, anticoagulant present before removal of cells. This variable increase proved to be due to variable release in vitro of transcobalamin III (TC III) from granulocytes. UBBC increase was greatest (up to fourfold normal levels) in the presence of lithium, which is the heparin salt used in many laboratories doing UBBC studies. In vitro increase was least when blood was collected in EDTA at 0 degrees C and immediately centrifuges at 0 degrees C (T(0) sample); results equivalent to T(0) were obtained at room temperature even after several hours delay when 47 mM fluoride was present; either cold temperature or 47 mM fluoride appeared to prevent TC III release from granulocytes. The measured levels of the three transcobalamins with T(0) methods of collection, which presumably reflect most closely the in vivo circulating levels, suggest that TC I and TC III in normal plasms are of the same order of magnitude and together normally comprise less than 10% of the UBBC. Approximately 90% of the UBBC content of sonicates of peripheral blood granulocytes and of bone marrow aspirates of normal individuals appears to be TC III, with the rest being TC I. Thus, normal myelocytes, like normal granulocytes, appear to contain mainly TC III. No TC II was present in any of the sonicates. The general practice in most laboratories has been to determine serum UBBC. Because in vitro increments of up to 119% were found to occur in serum, this practice should be replaced by collection using methods that prevent such increments. Blood collected in EDTA-47 mM NaF had a stable, reproducible UBBC with no significant in vitro increment with time.EDTA-NaF UBBC was 640+/-168 (range 380-921 pg B(12) bound/ml plasma) for 12 normal adult men and 809+/-232 (range 505-1208) for normal adult women. It presumably approximates circulating UBBC and is substantially below the serum UBBC mean of 935+/-262 (range 611-1506 for the same 12 men) and 1273+/-355 (range 811-2306 for the same 10 women).

Adult↗
PubMed2002

Evaluation of four techniques of warming intravenous fluids.

PURPOSE: This study was conducted to compare the fluid warming capabilities at different flow rates in four different warming systems. METHODS: The intravenous (i.v.) fluid warmers used in this study were a water-bath warmer, a forced-air warmer, a dry-heat plate warmer, and an i.v. fluid tube warmer. Ringer's solution at room temperature or at ice-cold temperature (120-3000 ml.h(-1)) was used as an i.v. fluid, and the i.v. fluid temperatures were measured with thermocouples at the end of a 1-m tube connected to the warmer. RESULTS: The temperature of the i.v. fluid delivered by the water bath and the forced-air warming system increased as the flow rate increased up to 1200 ml.h(-1) but decreased with further increase of the flow rate. The temperature of the i.v. fluid delivered by the dry-heat plate warmer significantly increased as the flow rate increased within the range studied. The delivered temperature did not depend on the flow rate within the range studied when the i.v. fluid tube warmer was used. CONCLUSION: It is important to choose a warmer according to its characteristics as well as its performance.

Journal Article↗
PubMed1996

High lipid content enhances the rate of oxygen diffusion through fish skeletal muscle.

The diffusion coefficient for O2 (Do2) and the solubility constant for O2 (alpha O2) were measured at 15 degrees C in oxidative muscle from striped bass (Morone saxatilis) that had been acclimated to 5 degrees and 25 degrees C. This design allowed us to test the hypothesis that changes in composition of the tissue that are known to occur during thermal acclimation may affect O2 movement. Our measurements permitted calculation of the diffusion constant for O2 (Ko2) through the tissue, which is a primary determinant of capacity for O2 flux. Under isothermal conditions, alpha O2 was 3.59 +/- 0.20 x 10(-2) and 6.64 +/- 0.27 x 10(-2) ml O2.cm-3.atm-1 in tissues from 25 degrees- and 5 degrees C-acclimated animals, respectively. Because O2 is more soluble in lipid than aqueous phase, higher alpha O2 in tissues from cold-acclimated animals can be accounted for by the 13-fold increase in lipid content that is known to occur in oxidative muscle of striped bass during acclimation from 25 degrees to 5 degrees C. When measured under similar isothermal conditions, Do2 showed no significant difference between animals acclimated to warm or cold temperature; Do2 through tissues from 25 degrees- and 5 degrees C-acclimated animals was 2.50 +/- 0.18 and 2.57 +/- 0.40 cm2/s, respectively. Because alpha O2 increases, the calculated KO2 (DO2. alpha O2) is greater in tissue from cold- than from warm-acclimated fish. At physiological temperature, elevated lipid content in oxidative muscle of cold-acclimated striped bass should result in enhanced intracellular movement of O2 and at least partially offset the expected decrease in DO2 at cold temperature.

Acclimatization↗
PubMedDate not supplied

Increased absolute light sensitivity in Himalayan mice with cold-induced ocular pigmentation.

Controversy over the relationship between ocular pigmentation and absolute dark-adapted light sensitivity has persisted for over two decades. Previous electrophysiological experiments in hypopigmented mammals (mice, rats, rabbits) show increased thresholds in the dark-adapted state proportional to the deficit in ocular melanin. Animals with the least amount of ocular melanin have the most elevated thresholds. Dark-adapted thresholds in hypopigmented mice show similar threshold elevations in behavioral tests. The present study extends these findings to show that a specific increase in ocular pigmentation results in the converse effect, lowered absolute dark-adapted thresholds. The increase in ocular melanin was accomplished by keeping Himalayan mice in the cold (4 degrees C) for 6 weeks. Himalayan mice (C57BL/6J cH/cH) were compared to black mice (C57BL/6J (+/+)) and albino mice (C57BL/6J c2J/c2J) after 6 weeks at either 4 degrees C or 20 degrees C in 12-h cycling light (<1 cd/m2). The Himalayan mice that were kept in the cold exhibited a 44% increase in ocular melanin compared to Himalayan mice kept at room temperature. Cold rearing did not effect ocular melanin or visual thresholds in control animals (black mice = 10(-5.9) cd/m2 and albino mice = 10(-4.4) cd/m2). In contrast, the Himalayan mice maintained at 4 degrees C had thresholds of 10(-5.7) cd/m2 compared to 10(-5.1) cd/m2 for Himalayan mice kept at 20 degrees C. This represents compelling evidence of a direct relationship between ocular melanin concentration and absolute dark-adapted light sensitivity.

Animals↗
PubMed1983

Cold pressor test and variant angina.

A transient complete coronary occlusion due to spasm was induced by the cold pressor test in a 51-year-old man with variant angina. Arteriography before the test revealed a normal left coronary artery and only minor irregularities of the mid-portion of the right coronary artery. Three minutes after cold stimulation, angina pectoris accompanied by ST-segment elevation was observed in lead II ECG. Simultaneous coronary arteriography during the attack showed a complete occlusion of the proximal right coronary artery due to spasm. The anginal attack together with spastic occlusion disappeared after administration of 0.8 mg of nitroglycerin. Thus, the cold pressor test can trigger coronary artery spasm and may even lead to a total occlusion in patients with variant angina. Individuals with variant angina may be subjected to additional risk when exposed to cold temperatures.

Angina Pectoris, Variant↗
PubMed1993

Removal of beta III isotype enhances taxol induced microtubule assembly.

The interaction of beta III-depleted tubulin with taxol was investigated. A monoclonal antibody against the beta III tubulin isotype was immobilized on a sepharose 4B column and used to remove the beta III tubulin isotype from unfractionated tubulin. The assembly of beta III-depleted tubulin in the presence of taxol was enhanced compared to unfractionated tubulin. The critical concentration of unfractionated tubulin in the presence of 10 microM taxol is 0.4 mg/ml, while the critical concentration of beta III-depleted tubulin is 0.16 mg/ml. At different concentration of taxol, the assembly of beta III-depleted tubulin is increased relative to that of unfractionated tubulin and reaches the maximum at about a 1:1 ratio of tubulin and taxol. The assembly of unfractionated tubulin and beta III-depleted tubulin has also been studied by electron microscopy. After 2 minutes at 37 degrees C, unfractionated tubulin assembly in the presence of 10 microM taxol results only in ribbon-like and ring structures; there are no visible microtubules. By 5 minutes, microtubules appear and increase in length. The assembly of beta III-depleted tubulin in the presence of 10 microM taxol occurs more quickly. In contrast to the case with unfractionated tubulin, beta III-depleted tubulin assembles within 2 minutes into microtubules which increase in length with time. At 30 minutes, microtubules assembled from beta III-depleted tubulin are shorter than the microtubules assembled from unfractionated tubulin. There is no visible difference between the microtubules assembled from unfractionated tubulin and beta III-depleted tubulin. Taxol-induced beta III-depleted tubulin assembly is more resistant to the inhibiting effect of podophyllotoxin and colchicine. It is also less sensitive to the inhibiting effect of cold temperature.

Animals↗
PubMed1993

Immune cell and cortisol responses to physically and pharmacologically induced lowering of body core temperature.

In a placebo-controlled double-blind study described by Rammsayer and co-workers in this volume, we investigated the influence of decreased body core temperature (BCT) on responses of cortisol and the immune system. As described in the first paper, the decrease in BCT was achieved by: (a) exposure to ambient cold temperature of 5 degrees C for 20 min (CT group), or (b) application of a 5HT-1a agonist under normal temperature conditions (5HT group). A third group serving as control was exposed to normal temperature and placebo (NT group). The decrease of BCT seen in both CT and 5HT was accompanied by an increase in cortisol. This seemed to be due to stress experience in the CT group and to the pharmacological challenge in the 5HT group. The number of peripheral CD4+ cells was reduced in both experimental groups. This was not mediated by decreased BCT. In the CT group the reduction of CD4+ cells showed no relationship to changes in cortisol. However, in the 5HT group cortisol could be demonstrated to be the mediator of changes in peripheral CD4+ cells.

Adult↗
PubMed2006

Identification of low-temperature-regulated genes in the fire blight pathogen Erwinia amylovora.

Genes involved in pathogenicity of several plant pathogens were shown to be induced at relatively cold temperatures. Loci from the fire blight pathogen Erwinia amylovora (Burrill) induced at 18 degrees C were identified using the miniTn5 transposon that contains the promoterless reporter gene gusA coding for beta-glucuronidase (GUS). Certain mutants (2.7%) expressed GUS predominantly at 18 degrees C on minimal medium plates, indicating that the transposon had been inserted downstream of a putatively thermoregulated promoter. Those mutants were further screened with a quantitative GUS fluorometric assay. A total of 21 mutants were selected: 19 mutants had a transposon insertion in temperature-dependent genetic loci, with a 2.2- to 6.3-fold induction of gusA gene expression at 18 degrees C, and two mutants with impaired growth at 18 degrees C. Some of these genetic loci encoded (i) proteins implicated in flagella biosynthesis, biotin biosynthesis, multi-drug efflux, and type II secretion protein, and (ii) proteins of unknown function.

Bacterial Proteins↗