The dinosaurs of Arctic Alaska.
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Alaska↗
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Results for “Cold Climate”
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.
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The cold side of life: the upcoming International Polar Year promises great advances in the exploration of the polar regions.
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Adaptation, Physiological↗
Winter transport of Chernobyl radionuclides from a montane catchment to an ice-covered lake.
The amounts of 137Cs and 90Sr have been determined in the inflows and outflows of the Norwegian sub-alpine lake, Ovre Heimdalsvatn, in March/April during the period of ice-cover, when discharge is extremely stable. The lake is situated in an area contaminated by Chernobyl fallout. The transported course particulate plant material has been collected in traps; the particles and colloids have been removed from water samples by cross-flow ultrafiltration. On the basis of radionuclide inputs and outputs, lake budget calculations have been made for 137Cs and 90Sr during the period of ice-cover. Daily transport of radionuclides is considerably less than that observed during the spring snowmelt period when discharges are high. Size distribution patterns of Cs and Sr observed during winter are compared with previously published data from the same lake during the spring spate. The retention of 137Cs is similar in winter and spring, but retention of 90Sr is greater in winter.
Accidents↗
The effect of temperature on catalytic and regulatory functions of pyruvate kinases of the rainbow trout and the antarctic fish Trematomus bernacchii.
1. The effects of temperature on the catalytic and regulatory properties of pyruvate kinases from the temperate-zone rainbow trout and the Antarctic fish Trematomus bernacchii were examined. 2. The K(m) value of pyruvate kinase for one of its two substrates, phosphoenolpyruvate, is temperature-dependent, and is lowest at temperatures that closely coincide with the habitat temperatures of the two fishes. 3. Two regulatory functions of pyruvate kinase, feedforward activation by fructose diphosphate and feedback inhibition by ATP, are temperature-independent. Enzyme-ADP interaction is also temperature-independent. 4. It is concluded that enzyme-substrate and enzyme-modulator interactions are important factors in short-term and in evolutionary adaptations by poikilotherms to changes in temperature. Though the K(m) for substrate may vary in apparently adaptive manners, the regulatory functions of an enzyme appear to be unchanged over the range of temperatures experienced by the organism in Nature.
Adaptation, Physiological↗
Glucuronidation and glucosidation reactions in aquatic species in boreal regions.
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Animals↗
Saccharomyces cerevisiae wine yeast populations in a cold region in Argentinean Patagonia. A study at different fermentation scales.
AIMS: To study the diversity and dynamics of indigenous Saccharomyces wine populations during Malbec spontaneous fermentation, a representative Patagonian red wine, at both industrial and laboratory scale. METHODS AND RESULTS: Two molecular techniques, including restriction fragment length polymorphism of mitochondrial (mt) DNA and polymorphism of amplified delta interspersed element sequences, were used for characterization of indigenous yeasts at strain level. The mtDNA restriction patterns showed the major discriminative power; however, by combining the two molecular approaches it was possible to distinguish a larger number of strains and, therefore, draw more representative conclusions about yeast diversity. Although a great diversity of wild Saccharomyces cerevisiae strains was observed, only nine represented more than half of the total Saccharomyces yeast biota analysed; five of these were common and took over the Malbec must fermentation in both vinifications. CONCLUSIONS: Many different indigenous S. cerevisiae strains were identified; nevertheless, the dominant strains in both industrial and laboratory vinification processes were just a few and the same. SIGNIFICANCE AND IMPACT OF THE STUDY: Small-scale fermentation appears to be a valuable tool in winemaking, one especially helpful in evaluating microbiological aspects of as well as possible interactions between inoculated selected strains and native strains.
Argentina↗
Influence of glaciation on divergence patterns of the endemic minnow, Zacco pachycephalus, in Taiwan.
The genetic subdivision of the endemic minnow, Zacco pachycephalus, in 12 rivers of Taiwan was studied by allozyme electrophoresis. Among 26 loci surveyed, six were significantly differentiated among sites. Allozyme genotype frequencies within samples accord with Hardy-Weinberg expectations. A highly divergent genetic structure among sites (FST = 0.497) with low genetic variability within samples (H = 0.006-0.062, mean = 0.03) suggests that local populations originated from a small number of founders. UPGMA and Fitch trees derived from Nei's genetic distance and hierarchical analysis of FST values reveal that samples of Z. pachycephalus can be divided into northern, middle, and southern subgroups and that most genetic variation (87%) is distributed among rather than within groups. It is proposed that there were two isolated refugia during the most recent glacial period, and that populations of the southern group (Group I) originated from a southern refugium in Taiwan below the boundary of the Kaoping River, and other groups (Group II), including northern and middle subgroups, originated from a refugium located on the extinct land-bridge between Taiwan and mainland China. The postglacial division between northern and middle subgroups may be due to hydrological differences between these two regions.
Alleles↗
Glacial refugia of limber pine (Pinus flexilis James) inferred from the population structure of mitochondrial DNA.
To make inferences about the glacial refugia that harboured the limber pine, Pinus flexilis James, we examined the range-wide population structure of mitochondrial DNA (mtDNA) with eight size variants in the second intron of nad1. The data consisted of haplotypes from 704 trees collected from 40 localities. The value of FST for these populations was 0.80, which is a much larger value than has been reported for allozymes and chloroplast DNA (cpDNA) in limber pine, and it suggests that the number of seeds moving among localities per generation is approximately 0.12. Gene flow of this magnitude would allow mutation and subsequent genetic drift to have a substantial impact on the population structure of mtDNA. The majority of the mtDNA haplotypes are restricted to minor portions of the geographical range. The data are consistent with mtDNA differentiation in seven glacial refugia, followed by dispersal out of those refugia.
Alberta↗
Did the pleistocene glaciations promote divergence? Tests of explicit refugial models in montane grasshopprers.
There is a long-standing debate over whether or not the Pleistocene glaciations promoted speciation. While some models predict that extensive mixing of populations during interglacial expansion would have inhibited divergence, others postulate that divergence among allopatric glacial refuges or founder events during recolonization of previously glaciated areas would have promoted differentiation. Using a combination of traditional and coalescent based population genetic approaches, this study finds that the glaciations did not inhibit divergence among populations of the grasshopper Melanoplus oregonensis. Instead, drift associated with recolonization of previously glaciated areas, as well as divergence among multiple allopatric glacial refugia, have both contributed to differentiation in this montane grasshopper from the 'sky islands' of the northern Rocky Mountains. Significant population structure was detected by phylogenetic and FST analyses, including significant FST values among individual pairs of sky-island populations. In addition to clustering of haplotypes within populations, there is some evidence of regional phylogeographic structure, although none of the 'regional groups' form a monophyletic clade and there is a lack of concordance between the genealogical and geographical positions of some haplotypes. However, coalescent simulations confirm there is significant regional phylogeographic structure that most likely reflects divergence among multiple ancestral refugial populations, and indicate that it is very unlikely that the observed gene tree could have been produced by the fragmentation of a single widespread ancestral population. Thus, rather than inhibiting differentiation, the glaciations appear to have promoted population divergence in M. oregonensis, suggesting that they may have contributed to the radiation of Melanoplus species during the Pleistocene.
Animals↗
Low-temperature sensitivity and enhanced Bohr effect in red deer (Cervus elaphus) haemoglobin: a molecular adaptive strategy to life at high altitude and low temperature.
A study of the functional properties of haemoglobin from red deer (Cervus elaphus) whose habitat varies over a wide range of latitude, was performed. The oxygen-binding properties of the most common haemoglobin phenotype from the species living in Sardinia were examined with particular attention to the effect of pH, chloride, 2, 3-bisphosphoglycerate and temperature. Results indicate that red deer haemoglobin, like all haemoglobins from ruminants so far examined, is characterized by a low intrinsic oxygen affinity, with chloride being its main physiological modulator in vivo. The functional results and the low temperature sensitivity of the oxygen affinity are discussed in the light of the amino acid sequence of closely related ruminant haemoglobins.
Adaptation, Physiological↗
Living in the cold: freeze-induced gene responses in freeze-tolerant vertebrates.
1. Winter survival for numerous cold-blooded animals includes freeze tolerance: the ability to endure the conversion of as much as 65% of total body water into extracellular ice. Selected molecular adaptations underlying freeze tolerance (e.g. cryoprotectants, ice nucleating proteins) have been widely studied, but the full range of metabolic adjustments needed for freeze endurance remains unknown. 2. Recent studies using gene screening techniques are providing a different approach to the search for biochemical responses that support freezing survival by identifying genes and proteins that are up-regulated by freezing or thawing in freeze-tolerant amphibians and reptiles. 3. Screening of a cDNA library from wood frog liver revealed the freeze-induced up-regulation of genes coding for the alpha- and gamma-subunits of fibrinogen (a plasma clotting protein), the mitochondrial ADP/ATP translocase and a novel 10 kDa protein containing a nuclear exporting sequence. 4. Northern blotting revealed that these genes were differentially responsive to two of the component stresses of freezing (dehydration and anoxia), indicating that different genes are induced by signals radiating either from cell volume change or oxygen deprivation during freezing. 5. Freeze up-regulation of fibrinogen synthesis in liver and other organs appears to be a damage repair response that anticipates a need for enhanced plasma clotting capacity to deal with ice crystal damage to capillary beds. 6. Up-regulation of ADP/ATP translocase in frog liver is linked with ischaemia resistance and studies with freeze-tolerant turtles have shown that other genes encoding proteins involved in mitochondrial energetics (NADH-ubiquinone oxido-reductase subunit 5, cytochrome C oxidase subunit 1) are also up-regulated by both anoxia and freezing exposures. 7. These studies are making major advances in our understanding of freeze tolerance as a natural phenomenon and also highlight new key areas that can be targeted by applied interventions for the optimization of medical cryopreservation techniques for cells, tissues and organs.
Amino Acid Sequence↗
Microbial diversity in ikaite tufa columns: an alkaline, cold ecological niche in Greenland.
Ikaite tufa columns from the Ikka Fjord in south-western Greenland constitute a natural, stable environment at low temperature and with a pH ranging from neutral at the exterior to very alkaline (pH 10.4) at the interior of the column. Phylogenetic analysis of culturable organisms revealed ten different isolates representing three of the major bacterial divisions. Nine of the isolates showed 94-99% similarity to known sequences, whereas one isolate displayed a low degree of similarity (less than 90%) to a Cyclobacterium species. Seven of the isolates were shown to be cold active alkaliphiles, whereas three isolates showed optimal growth at neutral pH. Phylogenetic analysis of DNA isolated directly from the ikaite material demonstrated the presence of a microbial flora more diverse than the culturable isolates. Whereas approximately half of the phylotypes showed 90-99% similarity to known meso- or thermophilic alkaliphiles, the rest of the sequences displayed less than 90% similarity when compared to known 16S rRNA gene sequences in databases. Thus, in the present paper, we demonstrate that ikaite columns that host a specialized macroscopic flora and fauna also contain a unique, cold active, alkaliphilic microflora.
Alkalies↗
Responses of poplar to chilling temperatures: proteomic and physiological aspects.
The effects of cold acclimation on primary metabolism in actively growing poplar ( Populus tremula L. x P. tremuloides Michaux) were studied. Three-month-old poplar plants were exposed to chilling stress (4 degrees C) and compared to plant material kept at a control temperature (23 degrees C). This treatment did not affect the survival of the plants but growth was almost stopped. The freezing tolerance of the adult leaves increased from -5.7 degrees C for the control plants to -9.8 degrees C after 14 days of exposure to 4 degrees C. During acclimation, the evolution of soluble carbohydrate contents was followed in the leaves. Sucrose, glucose, fructose and trehalose accumulated rapidly under chilling conditions, while raffinose content increased after one week at 4 degrees C. Proteomic analyses, by bidimensional electrophoresis, performed during this stage revealed that a large number of proteins had higher expression, while much less proteins disappeared or had a lower abundance. MALDI-TOF-MS analyses enabled ca. 30 spots to be proposed for candidate proteins. Among the accumulating or appearing proteins proposed, about a third presented similarities with chaperone-like proteins (heat shock proteins, chaperonins). In addition, dehydrins and other late embryogenesis abundant proteins, i.e., stress-responsive proteins, detoxifying enzymes, proteins involved in stress signalling and transduction pathways were also activated or newly synthesised. Finally, cold exposure induced a decrease in the candidate proteins involved in cell wall or energy production.
Acclimatization↗
Cold-acclimation increases insulin sensitivity of brown adipocytes.
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Acclimatization↗
Cold, fitness and the exercise electrocardiogram. A 20 year longitudinal study of Canadian Inuit.
A 20 year longitudinal study has examined fitness, lung function and exercise electrocardiograms in the Inuit of Igloolik (NWT, 69 degrees 40' N). When first examined (1969/70), an energy expenditure of up to 16 MJ/day was estimated from Kofranyi-Michaelis respirometry. Step test predictions of maximal oxygen intake were also high initially, but values declined progressively with acculturation to a sedentary lifestyle. Throughout the 20 years, right-branch bundle block (RBBB) has been somewhat more prevalent than in southern Canada. The majority of those affected have shown no more than slight R-wave notching. In 1969/70, a few of the more marked cases of RBBB may have been attributable to chronic respiratory disease, but the majority of cases have shown high normal values for both lung function and maximal oxygen intake. We thus conclude that the major cause of RBBB in this community is a ventricular hypertrophy due to the vigorous physical demands of the traditional lifestyle.
Adolescent↗
A prominent role for the CBF cold response pathway in configuring the low-temperature metabolome of Arabidopsis.
The Arabidopsis CBF cold response pathway has a central role in cold acclimation, the process whereby plants increase in freezing tolerance in response to low nonfreezing temperatures. Here we examined the changes that occur in the Arabidopsis metabolome in response to low temperature and assessed the role of the CBF cold response pathway in bringing about these modifications. Of 434 metabolites monitored by GC-time-of-flight MS, 325 (75%) were found to increase in Arabidopsis Wassilewskija-2 (Ws-2) plants in response to low temperature. Of these 325 metabolites, 256 (79%) also increased in nonacclimated Ws-2 plants in response to overexpression of C-repeat/dehydration responsive element-binding factor (CBF)3. Extensive cold-induced changes also occurred in the metabolome of Arabidopsis Cape Verde Islands-1 (Cvi-1) plants, which were found to be less freezing tolerant than Ws-2 plants. However, low-temperature-induced expression of CBF1, CBF2, CBF3, and CBF-targeted genes was much lower in Cvi-1 than in Ws-2 plants, and the low-temperature metabolome of Cvi-1 plants was depleted in metabolites affected by CBF3 overexpression. Taken together, the results indicate that the metabolome of Arabidopsis is extensively reconfigured in response to low temperature, and that the CBF cold response pathway has a prominent role in this process.
Acclimatization↗