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Cold Adaptation (cold + adaptation)

Distribution by Scientific Domains

Life Sciences	73%
Chemistry	26%

Selected Abstracts

Cold adaptation in the marine bacterium, Sphingopyxis alaskensis, assessed using quantitative proteomics

ENVIRONMENTAL MICROBIOLOGY, Issue 10 2010
Lily Ting
Summary The cold marine environment constitutes a large proportion of the Earth's biosphere. Sphingopyxis alaskensis was isolated as a numerically abundant bacterium from several cold marine locations, and has been extensively studied as a model marine bacterium. Recently, a metabolic labelling platform was developed to comprehensively identify and quantify proteins from S. alaskensis. The approach incorporated data normalization and statistical validation for the purpose of generating highly confident quantitative proteomics data. Using this approach, we determined quantitative differences between cells grown at 10°C (low temperature) and 30°C (high temperature). Cold adaptation was linked to specific aspects of gene expression: a dedicated protein-folding system using GroESL, DnaK, DnaJ, GrpE, SecB, ClpB and PPIase; polyhydroxyalkanoate-associated storage materials; a link between enzymes in fatty acid metabolism and energy generation; de novo synthesis of polyunsaturated fatty acids in the membrane and cell wall; inorganic phosphate ion transport by a phosphate import PstB homologue; TonB-dependent receptor and bacterioferritin in iron homeostasis; histidine, tryptophan and proline amino acid metabolism; and a large number of proteins without annotated functions. This study provides a new level of understanding on how important marine bacteria can adapt to compete effectively in cold marine environments. This study is also a benchmark for comparative proteomic analyses with other important marine bacteria and other cold-adapted organisms. [source]

Osmotic shock tolerance and membrane fluidity of cold-adapted Cryptococcus flavescens OH 182.9, previously reported as C. nodaensis, a biocontrol agent of Fusarium head blight

FEMS YEAST RESEARCH, Issue 3 2007
Christopher A. Dunlap
Abstract Cryptococcus flavescens (previously reported as C. nodaensis), a biological control agent of Fusarium head blight, has been previously shown to have improved desiccation tolerance after cold adaptation. The goal of the current study was to determine the effect of cold adaptation on the physicochemical properties of C. flavescens that may be responsible for its improved desiccation tolerance. The results show that cold adaptation improves liquid hyperosmotic shock tolerance and alters the temperature dependence of osmotic shock tolerance. Fluorescence anisotropy was used to characterize differences in the membrane fluidity of C. flavescens with and without cold adaptation. Force curves from atomic force microscopy showed a significant increase in the cell wall spring constant after cold adaptation. Cold adaptation of C. flavescens during culturing was shown to produce smaller cells and produced a trend towards higher CFU yields. These results suggest that cold adaptation significantly alters the membrane properties of C. flavescens and may be an effective method of improving the desiccation tolerance of microorganisms. In addition, we provide information on the correct naming of the isolate as C. flavescens. [source]

Cold adaptation in geographical populations of Drosophila melanogaster: phenotypic plasticity is more important than genetic variability

FUNCTIONAL ECOLOGY, Issue 5 2004
A. AYRINHAC
Summary 1According to their geographical distribution, most Drosophila species may be classified as either temperate or tropical, and this pattern is assumed to reflect differences in their thermal adaptation, especially in their cold tolerance. We investigated cold tolerance in a global collection of D. melanogaster by monitoring the time adults take to recover from chill coma after a treatment at 0 °C. 2Flies grown at an intermediate temperature (21 °C) showed a significant linear latitudinal cline: recovery was faster in populations living in colder climates. 3The role of growth temperature was analysed in a subset of tropical and temperate populations. In all cases, recovery time decreased when growth temperature was lowered, and linear reaction norms were observed. This adaptive phenotypic plasticity explained more than 80% of the total variation, while genetic latitudinal differences accounted for less than 4%. 4The beneficial effect observed in adults grown at a low temperature contrasts with other phenotypic effects which, like male sterility, appear as harmful and pathological. Our results point to the difficulty of finding a general interpretation to the diversity of plastic responses that are induced by growth temperature variations. [source]

Cold adaptation in Arctic and Antarctic fungi

NEW PHYTOLOGIST, Issue 2 2001
Clare H. Robinson
Summary Growth and activity at low temperatures and possible physiological and ecological mechanisms underlying survival of fungi isolated from the cold Arctic and Antarctic are reviewed here. Physiological mechanisms conferring cold tolerance in fungi are complex; they include increases in intracellular trehalose and polyol concentrations and unsaturated membrane lipids as well as secretion of antifreeze proteins and enzymes active at low temperatures. A combination of these mechanisms is necessary for the psychrotroph or psychrophile to function. Ecological mechanisms for survival might include cold avoidance; fungal spores may germinate annually in spring and summer, so avoiding the coldest months. Whether spores survive over winter or are dispersed from elsewhere is unknown. There are also few data on persistence of basidiomycete vs microfungal mycelia and on the relationship between low temperatures and the predominance of sterile mycelia in tundra soils. Acclimation of mycelia is a physiological adaptation to subzero temperatures; however, the extent to which this occurs in the natural environment is unclear. Melanin in dark septate hyphae, which predominate in polar soils, could protect hyphae from extreme temperatures and play a significant role in their persistence from year to year. [source]

Engineering the properties of a cold active enzyme through rational redesign of the active site

FEBS JOURNAL, Issue 19 2001
Iason Tsigos
,In an effort to explore the effects of local flexibility on the cold adaptation of enzymes, we designed point mutations aiming to modify side-chain flexibility at the active site of the psychrophilic alkaline phosphatase from the Antarctic strain TAB5. The mutagenesis targets were residues Trp260 and Ala219 of the catalytic site and His135 of the Mg2+ binding site. The replacement of Trp260 by Lys in mutant W260K, resulted in an enzyme less active than the wild-type in the temperature range 5,25 °C. The additional replacement of Ala219 by Asn in the double mutant W260K/A219N, resulted in a drastic increase in the energy of activation, which was reflected in a considerably decreased activity at temperatures of 5,15 °C and a significantly increased activity at 20,25 °C. Further substitution of His135 by Asp in the triple mutant W260K/A219N/H135D restored a low energy of activation. In addition, the His135,Asp replacement in mutants H135D and W260K/A219N/H135D resulted in considerable stabilization. These results suggest that the psychrophilic character of mutants can be established or masked by very slight variations of the wild-type sequence, which may affect active site flexibility through changes in various conformational constraints. [source]

Osmotic shock tolerance and membrane fluidity of cold-adapted Cryptococcus flavescens OH 182.9, previously reported as C. nodaensis, a biocontrol agent of Fusarium head blight

Metabolic cold adaptation and developmental plasticity in metabolic rates among species in the Fundulus notatus species complex

FUNCTIONAL ECOLOGY, Issue 5 2010
Jacob Schaefer
Summary 1.,In ectotherms, temperature and body size are the most influential and well studied variables affecting metabolic rate. Understanding mechanisms driving the evolution of metabolic rates is crucial to broader ecological theory. The metabolic cold adaptation hypothesis (MCA) makes predictions about the evolution of ectotherm metabolic rates and temperature-metabolic rate reaction norms. 2.,We examined intra and interspecific patterns in metabolic rate among populations in the Fundulus notatus species group (F. notatus, F. olivaceus and F. euryzonus). We ask if patterns of intra and interspecific variability in metabolic rate are consistent with the MCA and if metabolic rates in general are developmentally plastic. 3.,Support for the MCA was mixed among intra and interspecific tests. The northern population of F. olivaceus had increased metabolic rate and no difference in temperature sensitivity (slope of temperature-metabolic rate reaction norm). Northern populations of F. notatus had lower temperature sensitivity and no difference in overall metabolic rate. The southern coastal drainage endemic (F. euryzonus) had intermediate metabolic rates compared to southern populations of the other two more broadly distributed species. Metabolic rates were also developmentally plastic. Adults reared at warmer temperatures had lower metabolic rates after accounting for body size and temperature. 4.,Differences in thermal regimes explain some variability in metabolic rates among populations consistent with MCA. However, interspecific comparisons are not consistent with MCA and are likely influenced by species differences in ecology and life history strategies. [source]

Metabolic cold adaptation in arthropods: a smaller-scale perspective

FUNCTIONAL ECOLOGY, Issue 4 2003
I. D. Hodkinson
First page of article [source]

ANALYSIS OF EXPRESSED SEQUENCE TAGS (ESTS) FROM THE POLAR DIATOM FRAGILARIOPSIS CYLINDRUS,

JOURNAL OF PHYCOLOGY, Issue 1 2006
Thomas Mock
Analysis of expressed sequence tags (ESTs) was performed to gain insights into cold adaptation in the polar diatom Fragilariopsis cylindrus Grunow. The EST library was generated from RNA isolated 5 days after F. cylindrus cells were shifted from approximately +5° C to ,1.8°C. A total of 1376 ESTs were sequenced from a non-normalized cDNA library and assembled into 996 tentative unique sequences. About 27% of the ESTs displayed similarity (tBLASTX, e -value of ,10,4) to predicted proteins in the centric diatom Thalassiosira pseudonana Hasle & Heindal. Eleven additional algae and plant data bases were used for annotation of sequences not covered by Thalassiosira sequences (7%). Most of the ESTs were similar to genes encoding proteins responsible for translation, ribosomal structure, and biogenesis (3%), followed by genes encoding proteins for amino acid transport and metabolism and post-translational modifications. Interestingly, 66% of all the EST sequences from F. cylindrus displayed no similarity (e -value ,10,4) to sequences from the 12 non-redundant databases. Even 6 of the 10 strong to moderately expressed sequences in this EST library could not be identified. Adaptation of F. cylindrus to freezing temperatures of seawater may require a complex protein metabolism and possibly also genes, which were highly expressed but still unknown. However, it could also mean that due to low temperatures, there might have been a stronger pressure to adapt amino acid sequences, making it more difficult to identify these unknown sequences and/or that there are still few protist sequences available for comparison. [source]

Influence of environmental temperature on composition of lipids in edible flesh of rainbow trout (Oncorhynchus mykiss)

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 14 2003
Antonella Calabretti
Abstract The adaptative changes in the fatty acid composition of the main lipid classes in rainbow trout (Oncorhynchus mykiss) edible flesh in response to environmental variation in water temperature were investigated. The research was carried out on intensively farmed trout sampled at different times of the year. Neutral lipids (NL), phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were separated using flash chromatography. Compared with summer acclimatisation, a decrease in neutral lipids of about 19% was observed in winter, accompanied by increases in phosphatidylethanolamine and phosphatidylcholine of about 41 and 29%, respectively. The metabolic adjustment in cold adaptation caused an increase in the levels of unsaturated fatty acids and monoenes of the oleic acid ,9 family and an increase in the levels of unsaturated fatty acids of the linoleic acid ,3 family. At the same time a reduction in the levels of saturated and monounsaturated fatty acids of the oleic acid ,9 family was observed. This pattern turned out to be particularly evident in phosphatidylcholine. The net result of these changes in composition was a significant increase in the polyunsaturated/saturated and polyunsaturated/monoenic fatty acid ratios in the edible flesh. Copyright © 2003 Society of Chemical Industry [source]

Cold-shock-induced de novo transcription and translation of infA and role of IF1 during cold adaptation

MOLECULAR MICROBIOLOGY, Issue 3 2007
Mara Giangrossi
Summary Escherichia coli infA is transcribed from two promoters, P1 and P2, into a longer and a shorter mRNA encoding translation initiation factor IF1. Although P1 is intrinsically stronger than P2, the shorter half-life of its transcripts causes the steady-state level of the P2 transcript to be substantially higher than that of P1 during growth at 37°C. After cold-shock, de novo transcription and translation of infA contribute to the transient increase of the IF1/ribosomes ratio, which is partially responsible for translational bias consisting in the preferential translation of cold-shock mRNAs in the cold. Cold-stress induction of infA expression is mainly due to the high activity of P1 at low temperature, which is further increased by transcriptional stimulation by CspA and by an increased transcript stability. Furthermore, the longer infA mRNA originating from P1 is preferentially translated at low temperature by the translational machinery of cold-shocked cells. The increased level of IF1 during cold adaptation is essential for overcoming the higher stability of the 70S monomers at low temperature and for providing a sufficient pool of dissociated 30S subunits capable of initiating translation. [source]

Neandertal cold adaptation: Physiological and energetic factors

AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 5 2002
A. Theodore Steegmann Jr.
European Neandertals employed a complex set of physiological cold defenses, homologous to those seen in contemporary humans and nonhuman primates. While Neandertal morphological patterns, such as foreshortened extremities and low relative surface-area, may have explained some of the variance in cold resistance, it is suggested the adaptive package was strongly dependent on a rich array of physiological defenses. A summary of the environmental cold conditions in which the Neandertals lived is presented, and a comparative ethnographic model from Tierra del Fuego is used. Muscle and subcutaneous fat are excellent "passive" insulators. Neandertals were quite muscular, but it is unlikely that they could maintain enough superficial body fat to offer much cold protection. A major, high-energy metabolic adaptation facilitated by modest amounts of highly thermogenic brown adipose tissue (BAT) is proposed. In addition, Neandertals would have been protected by general mammalian cold defenses based on systemic vasoconstriction and intensified by acclimatization, aerobic fitness, and localized cold-induced vasodilation. However, these defenses are energetically expensive. Based on contemporary data from circumpolar peoples, it is estimated that Neandertals required 3,360 to 4,480 kcal per day to support strenuous winter foraging and cold resistance costs. Several specific genetic cold adaptations are also proposed,heat shock protein (actually, stress shock protein), an ACP*1 locus somatic growth factor, and a specialized calcium metabolism not as yet understood. Am. J. Hum. Biol. 14:566,583, 2002. © 2002 Wiley-Liss, Inc. [source]

Low temperature-induced systems failure in Escherichia coli: Insights from rescue by cold-adapted chaperones

PROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 1 2006
Massimo Strocchi
Abstract The growth of Escherichia coli cells is impaired at temperatures below 21°C and stops at 7.5°C; however, growth of a transgenic strain producing the cold-adapted chaperones Cpn60 and Cpn10 from the psychrophilic bacterium Oleispira antarctica is good at low temperatures. The E.,coli,cpn+ transgene offers a novel opportunity for examining the essential protein for cell viability at low temperatures. By screening a large-scale protein map (proteome) of cells of K-12 and its Cpn+ transgene incubated at 4°C, we identified 22,housekeeping proteins involved in systems failure of E.,coli when confronted with low temperature. Through co-immunoprecipitation of Cpn60, Northern blot, and in vitro refolding, we systematically identified that protein,chaperone interactions are key determinants of their protein functions at low temperatures. Furthermore, chromosomal gene deletion experiments suggest that the mechanism of cold-induced systems failure in E.,coli is cold-induced inactivation of the GroELS chaperonins and the resulting failure to refold cold-inactivated Dps, ClpB, DnaK and RpsB proteins. These findings: (1),indicate the potential importance of chaperones in cold sensitivity, cold adaptation and cold tolerance in cellular systems, and (2),suggest the identity of a few key cold-sensitive chaperone-interacting proteins that get inactivated and ultimately cause systems failure in E.,coli cells at low temperatures. [source]

The first structure of a cold-active catalase from Vibrio salmonicida at 1.96,Å reveals structural aspects of cold adaptation

ACTA CRYSTALLOGRAPHICA SECTION D, Issue 2 2007
Ellen Kristin Riise
The cold-adapted catalase from the fish-pathogenic bacterium Vibrio salmonicida (VSC) has recently been characterized and shown to be two times more catalytically efficient compared with catalase from the mesophilic human pathogen Proteus mirabilis [PMC; Lorentzen et al. (2006), Extremophiles, 10, 427,440]. VSC is also less temperature-stable, with a half-life of 5,min at 333,K compared with 50,min for PMC. This was the background for solving the crystal structure of the cold-adapted VSC to 1.96,Å and performing an extensive structural comparison of VSC and PMC. The comparison revealed that the entrance (the major channel) leading to the catalytically essential haem group, is locally more flexible and slightly wider in VSC. This might explain the enhanced catalytic efficiency of the nearly diffusion-controlled degradation of hydrogen peroxide into water and molecular oxygen in VSC. The reduced thermal stability of the cold-adapted VSC may be explained by a reduced number of ion-pair networks. The four C-terminal ,-helices are displaced in the structures, probably owing to missing ionic interactions in VSC compared with PMC, and this is postulated as an initiation site for unfolding the cold-adapted enzyme. VSC is the first crystal structure reported of a cold-adapted monofunctional haem-containing catalase. [source]

Expression, purification, crystallization and preliminary X-ray crystallographic studies of a psychrophilic cellulase from Pseudoalteromonas haloplanktis

ACTA CRYSTALLOGRAPHICA SECTION D, Issue 7 2003
Sébastien Violot
The Antarctic psychrophile Pseudoalteromonas haloplanktis produces a cold-active cellulase. To date, a three-dimensional structure of a psychrophilic cellulase has been lacking. Crystallographic studies of this cold-adapted enzyme have therefore been initiated in order to contribute to the understanding of the molecular basis of the cold adaptation and the high catalytic efficiency of the enzyme at low and moderate temperatures. The catalytic core domain of the psychrophilic cellulase CelG from P. haloplanktis has been expressed, purified and crystallized and a complete diffraction data set to 1.8,Å has been collected. The space group was found to be P212121, with unit-cell parameters a = 135.1, b = 78.4, c = 44.1,Å. A molecular-replacement solution, using the structure of the mesophilic counterpart Cel5A from Erwinia chrysanthemi as a search model, has been found. [source]

Improvement of low-temperature caseinolytic activity of a thermophilic subtilase by directed evolution and site-directed mutagenesis

BIOTECHNOLOGY & BIOENGINEERING, Issue 5 2009
Chuan-Qi Zhong
Abstract By directed evolution and subsequent site-directed mutagenesis, cold-adapted variants of WF146 protease, a thermophilic subtilase, have been successfully engineered. A four-amino acid substitution variant RTN29 displayed a sixfold increase in caseinolytic activity in the temperature range of 15,25°C, a down-shift of optimum temperature by ,15°C, as well as a decrease in thermostability, indicating it follows the general principle of trade-off between activity and stability. Nevertheless, to some extent RTN29 remained its thermophilic nature, and no loss of activity was observed after heat-treatment at 60°C for 2,h. Notably, RTN29 exhibited a lower hydrolytic activity toward suc-AAPF-pNA, due to an increase in Km and a decrease in kcat, in contrast to other artificially cold-adapted subtilases with increased low-temperature activity toward small synthetic substrates. All mutations (S100P, G108S, D114G, M137T, T153A, and S246N) identified in the cold-adapted variants occurred within or near the substrate-binding region. None of these mutations, however, match the corresponding sites in naturally psychrophilic and other artificially cold-adapted subtilases, implying there are multiple routes to cold adaptation. Homology modeling and structural analysis demonstrated that these mutations led to an increase in mobility of substrate-binding region and a modulation of substrate specificity, which seemed to account for the improvement of the enzyme's catalytic activity toward macromolecular substrates at lower temperatures. Our study may provide valuable information needed to develop enzymes coupling high stability and high low-temperature activity, which are highly desired for industrial use. Biotechnol. Bioeng. 2009; 104: 862,870. © 2009 Wiley Periodicals, Inc. [source]