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PubMed1982

The effect of interscapular brown adipose tissue removal on body-weight and cold response in the mouse.

1. The removal of the interscapular brown adipose tissue (IBAT) led to an increase in body-weight of normal, lean mice as compared to anaesthetized controls. 2. No significant difference in food consumption could be detected between the two groups of mice over the period of the experiment. 3. Fat extraction of the whole carcasses with chloroform:methanol showed a statistically significant increase in fat content in the animals without IBAT. 4. There was no apparent failure in the operated animals to sustain core temperature when exposed to a cold stress situation (4 degrees for 24 h). 5. There was no difference in the wet weight, protein content or cytochrome oxidase content of the dorso-cervical brown adipose tissue (DCBAT) between operated and control mice. This is indicative of a lack of proliferation of other brown adipose tissue sites in the operated mice in response to the removal of the IBAT. 6. It is suggested that brown adipose tissue is implicated in dietary thermogenesis in the mouse.

Adipose Tissue, Brown↗
PubMed2003

OsDREB genes in rice, Oryza sativa L., encode transcription activators that function in drought-, high-salt- and cold-responsive gene expression.

The transcription factors DREBs/CBFs specifically interact with the dehydration-responsive element/C-repeat (DRE/CRT) cis-acting element (core motif: G/ACCGAC) and control the expression of many stress-inducible genes in Arabidopsis. In rice, we isolated five cDNAs for DREB homologs: OsDREB1A, OsDREB1B, OsDREB1C, OsDREB1D, and OsDREB2A. Expression of OsDREB1A and OsDREB1B was induced by cold, whereas expression of OsDREB2A was induced by dehydration and high-salt stresses. The OsDREB1A and OsDREB2A proteins specifically bound to DRE and activated the transcription of the GUS reporter gene driven by DRE in rice protoplasts. Over-expression of OsDREB1A in transgenic Arabidopsis induced over-expression of target stress-inducible genes of Arabidopsis DREB1A resulting in plants with higher tolerance to drought, high-salt, and freezing stresses. This indicated that OsDREB1A has functional similarity to DREB1A. However, in microarray and RNA blot analyses, some stress-inducible target genes of the DREB1A proteins that have only ACCGAC as DRE were not over-expressed in the OsDREB1A transgenic Arabidopsis. The OsDREB1A protein bound to GCCGAC more preferentially than to ACCGAC whereas the DREB1A proteins bound to both GCCGAC and ACCGAC efficiently. The structures of DREB1-type ERF/AP2 domains in monocots are closely related to each other as compared with that in the dicots. OsDREB1A is potentially useful for producing transgenic monocots that are tolerant to drought, high-salt, and/or cold stresses.

Adaptation, Physiological↗
PubMed1999

cDNA sequence and expression of a cold-responsive gene in Citrus unshiu.

A cDNA clone encoding a protein (CuCOR19), the sequence of which is similar to Poncirus COR19, of the dehydrin family was isolated from the epicarp of Citrus unshiu. The molecular mass of the predicted protein was 18,980 daltons. CuCOR19 was highly hydrophilic and contained three repeating elements including Lys-rich motifs. The gene expression in leaves increased by cold stress.

Amino Acid Sequence↗
PubMed2004

Cloning and functional analysis of a novel DREB1/CBF transcription factor involved in cold-responsive gene expression in Zea mays L.

The transcription factors DREB1s/CBFs specifically interact with the DRE/CRT cis-acting element (core motif: G/ACCGAC) and control the expression of many stress-inducible genes in Arabidopsis. We isolated a cDNA for a DREB1/CBF homolog, ZmDREB1A in maize using a yeast one-hybrid system. The ZmDREB1A proteins specifically bound to DRE and the highly conserved valine at the 14th residue in the ERF/AP2 DNA binding domain was a key to determining the specific interaction between this protein and the DRE sequence. Expression of ZmDREB1A was induced by cold stress and slightly increased by high-salinity stress. This gene was also transiently expressed by mechanical attack. ZmDREB1A activated the transcription of the GUS reporter gene driven by DRE in rice protoplasts. Overexpression of ZmDREB1A in transgenic Arabidopsis induced overexpression of target stress-inducible genes of Arabidopsis DREB1A resulting in plants with higher tolerance to drought and freezing stresses. This indicated that ZmDREB1A has functional similarity to DREB1s/CBFs in Arabidopsis. The structure of the ERF/AP2 domain of ZmDREB1A in maize is closely related to DREB1-type ERF/AP2 domains in the monocots as compared with that in the dicots. ZmDREB1A is suggested to be potentially useful for producing transgenic plants that is tolerant to drought, high-salinity and/or cold stresses.

Amino Acid Sequence↗
PubMed2005

Cold response of the bladder in guinea pig: involvement of transient receptor potential channel, TRPM8.

OBJECTIVES: To address the physiologic role of TRPM8, one of the transient receptor potential channels, we investigated the bladder cooling reflex and the effect of menthol on it in the guinea pig. METHODS: Single cystometry in female Hartley guinea pigs was performed with high-speed infusion (60 mL/hr) under urethane anesthesia (1 g/kg intraperitoneally). The volume threshold for micturition (VT) and micturition pressure were determined. The distribution of TRPM8 in the S1 dorsal root ganglion (DRG) was also examined by immunostaining. RESULTS: Intravesical infusion of saline containing menthol (0.6 mM) at 38 degrees C markedly decreased the VT and increased micturition pressure. Although cold saline itself (4 degrees C) had little effect on VT or micturition pressure, the VT was significantly decreased in a temperature-dependent manner when the bladder was pretreated with menthol. This decrease in the VT was not observed in animals that received hexamethonium pretreatment (10 mg/kg intravenously), which blocks the spinal reflex, or capsaicin (1 mM intravesically), which causes deafferentation of capsaicin-sensitive C-fiber afferent. Immunohistochemical analysis revealed that TRPM8 is expressed in small-diameter neurons in guinea pig S1 dorsal root ganglions. CONCLUSIONS: The results of our study showed that the bladder cooling reflex is observed in guinea pigs if the animals were pretreated with menthol. This reflex was sensitive to ganglion blockade or capsaicin-sensitive C-fiber deafferentation and might be mediated by C-fiber activation through TRPM8.

Afferent Pathways↗
PubMed2005

Expression analysis of a cold responsive transcript from trifoliate orange by real-time PCR and RT-PCR.

CLTa and CLTb are two transcripts produced by the citrus CLT gene. CLTb is constitutively expressed, while CLTa is a low temperature responsive transcript expressed in temperatures below 10 degrees C during the acclimation process of some species of citrus. Real-time PCR was used to study CLTa expression pattern in trifoliate orange during acclimation, gradual deacclimation and abrupt deacclimation. A standard curve of nine dilution series from 10 x 10(6) to 10 x 10(-3) fg was constructed, using part of the CLTa transcript, which enabled us to determine the concentration of the transcript at different temperatures and conditions. It was found that during acclimation, CLTa expression is first detected at 10 degrees C, reaching a maximum after 24 h of exposure at -1 degrees C. During gradual deacclimation, the transcript accumulated at 5 degrees C and after this point it degrades, reaching a low level at 10 degrees C. When the plants were abruptly transferred to room temperature after being acclimated to -1 degrees C, the transcript reduced from 11,303 fg to levels below the threshold 3 h later, indicating a rapid degradation and how the expression of CLTa is dependent on low temperature. Exposure of trifoliate plants to abscisic acid (ABA) and salts indicated that CLTa is not induced by these treatments at the concentrations used. CLTa expression was also verified in other citrus species and was not detected in the acclimated cold-sensitive species "Mexican lime" (Citrus aurantifolia Swing.) and in the cold hardy "Satsuma mandarin (C. unchiu Marc.).

Abscisic Acid↗
PubMed2000

Chitinase genes responsive to cold encode antifreeze proteins in winter cereals.

Antifreeze proteins similar to two different chitinases accumulate during cold acclimation in winter rye (Secale cereale). To determine whether these cold-responsive chitinases require post-translational modification to bind to ice, cDNAs coding for two different full-length chitinases were isolated from a cDNA library produced from cold-acclimated winter rye leaves. CHT9 is a 1,193-bp clone that encodes a 31.7-kD class I chitinase and CHT46 is a 998-bp clone that codes for a 24.8-kD class II chitinase. Chitinase-antifreeze proteins purified from the plant were similar in mass to the predicted mature products of CHT9 and CHT46, thus indicating that there was little chemical modification of the amino acid sequences in planta. To confirm these results, the mature sequences of CHT9 and CHT46 were expressed in Escherichia coli and the products of both cDNAs modified the growth of ice. Transcripts of both genes accumulated late in cold acclimation in winter rye. Southern analysis of winter rye genomic DNA indicated the presence of a small gene family homologous to CHT46. In hexaploid wheat, CHT46 homologs mapped to the homeologous group 1 chromosomes and were expressed in response to cold and drought. We conclude that two novel cold-responsive genes encoding chitinases with ice-binding activity may have arisen in winter rye and other cereals through gene duplication.

Amino Acid Sequence↗
PubMed2026

Unraveling epigenetic and genetic variations in response to cold stress in two lotus ecotypes.

Genetic variations accumulate over long evolutionary timescales, whereas epigenetic modifications can arise rapidly and be inherited across generations. However, the interplay between genetic and epigenetic variations in shaping ecotype-specific phenotypic plasticity remains elusive. Focusing on two lotus ecotypes that evolved under distinct winter temperature regions and display divergent annual growth cycles under cold stress, we generated DNA methylation landscapes across three sequence contexts (CG, CHG, and CHH, where H = A, T, or C) and identified single-cytosine methylation polymorphisms (SMPs) and single-nucleotide polymorphisms (SNPs). Interestingly, only CG methylation patterns mirror population-level genetic variations. Using epigenetic genome-wide association analysis, we identified differentially methylated CG sites that are either cis- or trans-regulated by SNP. Notably, we constructed a multifactorial regulatory network centered on the NnMKK4-NnCYCD5 module, linking cold response with cell cycle regulation. Temperature stress experiments conducted on lotus ecotypes and transgenic Arabidopsis (OE-NnMKK4 and OE-NnCYCD5) confirmed that NnMKK4 acts as a cold receptor and that NnCYCD5 promotes cell cycle progression and growth under cold conditions. Collectively, our findings provide novel insights into the co-evolutionary dynamics of epigenetic and genetic variations that are associated with different growth cycles of lotus ecotypes in response to cold stress.

DNA methylation↗
PubMed1990

A rapid cold-hardening response protecting against cold shock injury in Drosophila melanogaster.

In studies of insect cold-hardiness, the supercooling point (SCP) is defined as the temperature at which spontaneous nucleation of body fluids occurs. Despite having an SCP of -20 degrees C, adults of Drosophila melanogaster did not survive exposure to -5 degrees C, which suggests that cold shock causes lethal injury that is not associated with freezing. If, however, flies were chilled at 5 degrees C, for as little as 30 min, approximately 50% of the flies survived exposure to -5 degrees C for 2h. This capacity to cold-harden rapidly was greatest in 3- and 5-day-old adults. The rapid cold-hardening response was also observed in larvae and pupae: no larvae survived 2 h of exposure to -5 degrees C, whereas 63% pupariated if chilled at 5 degrees C before subzero exposure. Similarly, although exposure of pupae to -8 degrees C was lethal, if pre-chilled at 5 degrees C 22% eclosed. This extremely rapid cold-hardening response may function to allow insects to enhance cold-tolerance in response to diurnal or unexpected seasonal decreases in environmental temperature.

Age Factors↗
PubMed2006

Control and regulation of the cellular responses to cold shock: the responses in yeast and mammalian systems.

Although the cold-shock response has now been studied in a number of different organisms for several decades, it is only in the last few years that we have begun to understand the molecular mechanisms that govern adaptation to cold stress. Notably, all organisms from prokaryotes to plants and higher eukaryotes respond to cold shock in a comparatively similar manner. The general response of cells to cold stress is the elite and rapid overexpression of a small group of proteins, the so-called CSPs (cold-shock proteins). The most well characterized CSP is CspA, the major CSP expressed in Escherichia coli upon temperature downshift. More recently, a number of reports have shown that exposing yeast or mammalian cells to sub-physiological temperatures (<30 or <37 degrees C respectively) invokes a co-ordinated cellular response involving modulation of transcription, translation, metabolism, the cell cycle and the cell cytoskeleton. In the present review, we summarize the regulation and role of cold-shock genes and proteins in the adaptive response upon decreased temperature with particular reference to yeast and in vitro cultured mammalian cells. Finally, we present an integrated model for the co-ordinated responses required to maintain the viability and integrity of mammalian cells upon mild hypothermic cold shock.

Amino Acid Sequence↗
PubMed2000

Adaptive response to cold temperatures and characterization of cspA in Salmonella typhimurium LT2.

Salmonella typhimurium is a major foodborne microbial pathogen which primarily contaminates poultry products causing salmonellosis in humans. S. typhimurium LT2 cultures, when transferred from 37 degrees C to 5 degrees C or 10 degrees C, showed an initial lag period in growth with an approximate generation time of 10-25 h. Western blot assay using E. coli CS7.4 antibody and analysis of radiolabeled total cellular proteins from S. typhimurium cultures after exposure to 10 degrees C or 5 degrees C showed elevated expression of a major cold shock protein, CS7.4. Identification of a decreased level of CS7.4 at 37 degrees C suggests that the expression of this protein may require a large temperature downshift. Putative regulatory protein binding segment on the 5'-untranslated region referred as 'Fragment 7' in S. typhimurium exhibited a 90.6% and a 56.25% nucleotide sequence identity when compared with the Fragment 7 of E. coli and S. enteritidis, respectively. The differences in the nucleotide sequence within the Fragment 7 between S. typhimurium and S. enteritidis may explain the differential expression of CspA at 37 degrees C. The nucleotide sequence of the open reading frame of S. typhimurium cspA gene showed a single base difference at 816 bp position from a G to a C which altered the amino acid residue from a glycine to an alanine. In addition to CspA, an elevated expression of a 105 kDa, and decreased expression of 6 proteins were evidenced when cultures of S. typhimurium were exposed to 10 degrees C or 5 degrees C. Differential expression of the CspA and other proteins in S. typhimurium following exposure to cold temperatures suggest that adaptation and continued growth and survival at cold temperatures in this pathogen may be aided by these cold-responsive proteins.

Adaptation, Physiological↗
PubMed1999

Cold-shock response and cold-shock proteins.

Both prokaryotes and eukaryotes exhibit a cold-shock response upon an abrupt temperature downshift. Cold-shock proteins are synthesized to overcome the deleterious effects of cold shock. CspA, the major cold-shock protein of Escherichia coli, has recently been studied with respect to its structure, function and regulation at the level of transcription, translation and mRNA stability. Homologues of CspA are present in a number of bacteria. Widespread distribution, ancient origin, involvement in the protein translational machinery of the cell and the existence of multiple families in many organisms suggest that these proteins are indispensable for survival during cold-shock acclimation and that they are probably also important for growth under optimal conditions.

Adaptation, Biological↗