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PubMed1999

Involvement of a MAP kinase, ZmMPK5, in senescence and recovery from low-temperature stress in maize.

Four species of protein kinase were identified in senescent maize leaves using a gel assay for kinase activity with myelin basic protein (MBP) as the substrate. Most of these kinases were also found in healthy green leaves that had been exposed to low-temperature stress (5 degrees C) and then returned to 25 degrees C. A 41-kDa protein was activated in senescent leaves, whereas a 45-kDa protein was activated 3 h after up-shift from 5 degrees C to 25 degrees C as well as in senescent leaves. A 39-kDa protein was activated by cold stress. The other two proteins, of 35 kDa and 52 kDa, constitutively phosphorylated MBP during senescence and temperature up-shift. Judging from their molecular masses, cation requirements and substrate specificities, it seemed likely that the 39-kDa, 41-kDa and 45-kDa proteins represented mitogen-activated protein kinases (MAPKs). Subsequently two MAPK cDNAs were isolated from a cDNA library constructed using mRNAs from senescent leaves. Northern analysis showed that the transcript corresponding to one of the cDNAs, designated ZmMPK5, accumulated in healthy leaves 3 h after the up-shift to 25 degrees C as well as in senescent leaves, suggesting that the 45-kDa protein kinase is encoded by ZmMPK5. Western analysis using an antiserum against the C-terminal region of ZmMPK5 showed that the level of the ZmMPK5 protein increased in senescent leaves. These results indicate that a 45-kDa MAPK is involved in the process of senescence and in recovery from low-temperature stress in maize plants.

Amino Acid Sequence↗

PubMed2005

Mutational and expression analysis of ELIP1 and ELIP2 in Arabidopsis thaliana.

Plants exposed to photoinhibitory conditions respond by accumulation of the early light-induced proteins (ELIPs) with a potential photoprotective function. In Arabidopsis thaliana two genes (Elip1 and Elip2) encode for two ELIP proteins: evidence exists that the two genes are differentially regulated but their precise function is unclear. Mutants null for one or the other Elip gene can help in elucidating ELIPs role and here we describe the expression profile of ELIP1 and ELIP2, and the phenotype of such null mutants. Both ELIPs accumulate during greening of etiolated seedlings and in mature plants the transcripts fluctuate diurnally without protein accumulation. Steady-state transcript level of both genes increases in response to high light with transcription of Elip1 much more sensitive than that of Elip2 to increasing irradiation at 22 degrees C. At 4 degrees C instead Elip2 is strongly transcribed even at growing light. Furthermore, only ELIP1 accumulates under high light at 22 degrees C while both proteins accumulate at 4 degrees C. These results indicate the existence of a differential regulation of ELIPs expression in response to light or chilling stress with mechanisms active either at transcriptional and post-transcriptional level. Phenotypically, the mutants behave as the wild type as far as sensitivity to light- or light and cold-induced short-term photoinhibition, while both ELIPs are necessary to ensure a high rate of chlorophyll accumulation during deetiolation in continuous high light.

Arabidopsis↗

PubMed2005

Maize cystatins respond to developmental cues, cold stress and drought.

Comprehensive searches of maize EST data allowed us to identify 8 novel Corn Cystatin (CC) genes in addition to the previously known genes CCI and CCII. The deduced amino acid sequences of all 10 genes contain the typical cystatin family signature. In addition, they show an extended overall similarity with cystatins from other species that belong to several different phyto-cystatin subfamilies. To gain further insight into their respective roles in the maize plant, gene-specific expression profiles were established by semi-quantitative RT-PCR. While 7 CC genes were expressed in two or more tissues varying from gene to gene, CCI was preferentially expressed in immature tassels and CC8 and CC10 in developing kernels. As shown by in situ hybridisation of maize kernels, CC8 was specifically expressed in the basal region of the endosperm and CC10 both in the starchy endosperm and the scutellum of the embryo. The remaining, not kernel-specific genes, all had distinct expression kinetics during kernel development, generally with peaks during the early stages. In addition to developmental regulation, the effect of cold stress and water starvation were tested on cystatin expression. Two genes (CC8 and CC9) were induced by cold stress and 5 genes (CCII, CC3, CC4, CC5 and CC9) were down-regulated in response to water starvation. Taken together our data suggest distinct functions for CC genes in the maize plant.

Amino Acid Sequence↗

PubMed2006

Thermoperiodic acclimations enhance cold hardiness of the eggs of the migratory locust.

Treatment of thermoperiods that simulate the patterns of natural occurrence is most efficient in enhancing cold hardiness. To examine the effects of different thermoperiods on cold hardiness of eggs in the migratory locust, Locusta migratoria (L.), the survival rates, cryoprotectant levels and three hsps expressions in mid-stage eggs (7-day-old) were measured after the eggs were subjected to three different thermoperiod regimes, : short (2 day), long (10 day), and nature-mimicking thermoperiodic acclimation. The thermoperiodic acclimations resulted in the highest egg survival rates in both the short and the long period acclimation groups in comparison with the groups treated with constant temperatures. The egg survival of nature-mimicking thermoperiod groups was significantly higher than those of constant temperature groups for the same acclimation duration. The survival rate of eggs under single daily thermoperiod was higher than that of multiple daily thermoperiods. The concentration of cryoprotectants (myo-inositol, trehalose, mannitol and sorbitol) and the expression levels of hsp20.5, hsp70, and hsp90 all increased in thermoperiodic acclimation eggs.

Acclimatization↗

PubMed2000

Temperature-dependent vitellogenin-mRNA expression in primary cultures of rainbow trout (Oncorhynchus mykiss) hepatocytes at 14 and 18 degrees C.

In order to study the influence of temperature on vitellogenin gene and estrogen receptor gene expression in primary hepatocytes from rainbow trout (Oncorhynchus mykiss), cells were exposed to 17beta-estradiol, bisphenol-A and nonylphenol for 48 and 96 hr. Induction of vitellogenin-mRNA expression was detected in a non-radioactive dot blot/RNAse protection assay and by RT-PCR. In the dot blot/RNAse protection assay, the estrogenic potentials of bisphenol-A and nonylphenol were about 10(4)- to 10(5)-fold and 10(5)-fold lower than that of 17beta-estradiol, respectively. The relative estrogenic potential did not show any difference between 14 and 18 degrees C. In contrast, at 18 degrees C, RT-PCR analysis revealed increased amounts of vitellogenin- and estrogen receptor-mRNA after 12 and 24 hr of exposure to 17beta-estradiol, if compared to 14 degrees C. Owing to increased vitellogenin gene expression at 18 degrees C, the sensitivity of primary hepatocytes to 17beta-estradiol and bisphenol-A could be increased.

Animals↗

PubMed2001

Cloning of glycerol-3-phosphate dehydrogenase cDNAs from two fish species and effect of temperature on enzyme expression in rainbow smelt (Osmerus mordax).

Rainbow smelt (Osmerus mordax) can accumulate extreme levels of glycerol in their blood during winter. Low temperatures are required for glycerol accumulation in smelt blood and the enzyme glycerol-3-phosphate dehydrogenase (GPDH) has been suggested to play a role in glycerol production/concentration in this species. In the present study, cDNA sequences encoding glycerol-3-phosphate dehydrogenase (GPDH) from rainbow smelt and Atlantic salmon (Salmo salar) were cloned. The encoded GPDH protein sequences were very similar to one another (88% identity). Using RT-PCR, GPDH mRNA was detected in skin, gill, heart, head kidney, brain and liver from both salmon and smelt obtained in December. However, GPDH was not detected in salmon intestine and spleen or in smelt intestine. Examination of GPDH expression in smelt liver during February by Northern blotting revealed temperature regulation. Elevation of the temperature resulted in a significant decrease in liver GPDH transcript level. Serum glycerol levels decreased concomitantly. These findings suggest a role for GPDH in the accumulation of glycerol in smelt at low temperatures.

Amino Acid Sequence↗

PubMed2006

Amylose-lipid complexes as controlled lipid release agents during starch gelatinization and pasting.

The effect of amylose-lipid (AM-L) complexes consisting of amylose populations with different peak degrees of polymerization (DP) and complexed with glyceryl monostearate (GMS) or docosanoic acid (C22) on the pasting properties of wheat and rice starches was evaluated with a rapid visco analyzer (RVA). AM-L complexes were formed by both (i) addition of lipids to amylose fractions with peak DP 20, 60, 400, or 950 at 60 degrees C or (ii) potato phosphorylase-catalyzed amylose synthesis in the presence of lipids. All AM-L complexes affected pasting properties in line with their dissociation characteristics. AM-L complexes therefore have potential as "controlled lipid release agents" with effects markedly different from those observable with emulsifier addition in starch pasting. More in particular, short chain AM-L complexes resulted in a starch pasting behavior comparable to that of cross-linked starch, as evidenced by reduced granule swelling, good viscosity stability in conditions of high temperature and shear, and a stable cold paste viscosity.

Amylose↗

PubMed2004

Temperature-actuated changes in wettability at elastomer/water interfaces.

Surface modification of 1,4-polybutadiene and cis-1,4-polyisoprene to introduce polar functional groups provided surfaces that reconstructed reversibly against water as a function of temperature. These surfaces became hydrophobic in contact with hot water, but their original hydrophilicity returned upon equilibration against cold water. Repeated cycling between hot and cold water, however, led to a damping of this reversibility. A series of parallel experiments on both the interfacial and bulk behavior of these elastomers strongly indicated that this damping was due to the alignment of extended interfacial chains during temperature cycling and to a decay of the restoring force on the interfacial chains under extension. These studies thus demonstrate that the interfacial behavior of elastomers can display close analogies to the bulk viscoelastic properties of the solid.

Journal Article↗

PubMed2003

Supraglacial sulfur springs and associated biological activity in the Canadian high arctic-signs of life beneath the ice.

Unique springs, discharging from the surface of an arctic glacier, release H(2)S and deposit native sulfur, gypsum, and calcite. The presence of sulfur in three oxidation states indicates a complex series of redox reactions. Physical and chemical conditions of the spring water and surrounding environment, as well as mineralogical and isotopic signatures, suggest biologically mediated reactions. Cell counts and DNA analyses confirm bacteria are present in the spring system, and a limited number of sequenced isolates suggests that complex communities of bacteria live within the glacial system.

Arctic Regions↗

PubMed1975

Isolation of lipopolysaccharide from the walls of Micropolyspora faeni: chemical composition and serological reactivity.

Extraction of mycelium or walls of Micropolyspora faeni with cold or hot aqueous phenol yielded a lipopolysaccharide consisting of lipid A, phosphate, galactose, arabinose, glucose, glucosamine, and a dideoxy sugar. Extraction with trichloroacetic acid (TCA) yielded an incomplete molecule lacking lipid A. Part of an O-chain was secreted into the culture medium. Phenol and TCA extracts gave three lines of precipitation with human serum from cases of farmer's lung disease, and one of these was given by the culture medium polysaccharide. Serologically-reactive sugars were arabinose, galactose and glucose. The lipopolysaccharide fixed on to red cells which agglutinated in the presence of specific antibody and lysed on the addition of complement. The lipopolysaccharide appeared to elicit mainly IgM antibodies in animals, but IgM and IgG antibodies in humans.

Actinomycetales↗

PubMed1999

Cold-adapted alanine dehydrogenases from two antarctic bacterial strains: gene cloning, protein characterization, and comparison with mesophilic and thermophilic counterparts.

The genes encoding NAD(+)-dependent alanine dehydrogenases (AlaDHs) (EC 1.4.1.1) from the Antarctic bacterial organisms Shewanella sp. strain Ac10 (SheAlaDH) and Carnobacterium sp. strain St2 (CarAlaDH) were cloned and expressed in Escherichia coli. Of all of the AlaDHs that have been sequenced, SheAlaDH exhibited the highest level of sequence similarity to the AlaDH from the gram-negative bacterium Vibrio proteolyticus (VprAlaDH). CarAlaDH was most similar to AlaDHs from mesophilic and thermophilic Bacillus strains. SheAlaDH and CarAlaDH had features typical of cold-adapted enzymes; both the optimal temperature for catalytic activity and the temperature limit for retaining thermostability were lower than the values obtained for the mesophilic counterparts. The k(cat)/K(m) value for the SheAlaDH reaction was about three times higher than the k(cat)/K(m) value for VprAlaDH, but it was much lower than the k(cat)/K(m) value for the AlaDH from Bacillus subtilis. Homology-based structural models of various AlaDHs, including the two psychotropic AlaDHs, were constructed. The thermal instability of SheAlaDH and CarAlaDH may result from relatively low numbers of salt bridges in these proteins.

Adaptation, Physiological↗

PubMed1998

Viruses and bacteria in the etiology of the common cold.

Two hundred young adults with common colds were studied during a 10-month period. Virus culture, antigen detection, PCR, and serology with paired samples were used to identify the infection. Viral etiology was established for 138 of the 200 patients (69%). Rhinoviruses were detected in 105 patients, coronavirus OC43 or 229E infection was detected in 17, influenza A or B virus was detected in 12, and single infections with parainfluenza virus, respiratory syncytial virus, adenovirus, and enterovirus were found in 14 patients. Evidence for bacterial infection was found in seven patients. Four patients had a rise in antibodies against Chlamydia pneumoniae, one had a rise in antibodies against Haemophilus influenzae, one had a rise in antibodies against Streptococcus pneumoniae, and one had immunoglobulin M antibodies against Mycoplasma pneumoniae. The results show that although approximately 50% of episodes of the common cold were caused by rhinoviruses, the etiology can vary depending on the epidemiological situation with regard to circulating viruses. Bacterial infections were rare, supporting the concept that the common cold is almost exclusively a viral disease.

Adenovirus Infections, Human↗

PubMed2001

Type 2 rhinovirus infection of cultured human tracheal epithelial cells: role of LDL receptor.

To examine the role of the low-density lipoprotein (LDL) receptor on minor group human rhinovirus (RV) infection, primary cultures of human tracheal epithelial cells were infected with a minor group (RV2) or a major group (RV14) RV. Viral infection was confirmed by showing with PCR that viral titers in supernatants and lysates from infected cells increased with time. RV2 and RV14 increased expression of mRNA and protein of the LDL receptor on the cells and the cytokine production. RV2 induced activation of transcription factors SP1 and nuclear factor-kappaB (NF-kappaB). An antibody to the LDL receptor inhibited RV2 infection and RV2-induced cytokine production without an effect on RV14 infection and RV14-induced cytokine production. These findings imply that RV2 upregulates LDL receptor expression on airway epithelial cells, thereby increasing susceptibility to minor group RV infection. LDL receptor expression and cytokine production may be mediated, in part, via activation of transcription factors by RV2. These events may be important in airway inflammation after minor group RV infection in asthma.

Aged↗

PubMed2005

Differential and coordinated expression of Cbf and Cor/Lea genes during long-term cold acclimation in two wheat cultivars showing distinct levels of freezing tolerance.

The cold acclimation process in plants is primarily regulated through the signal transduction pathways that lead to the induction and enhancement of expression of different sets of Cor/Lea genes. Winter wheat 'Mironovskaya 808' (M808) exhibited a much higher level of freezing tolerance than spring wheat 'Chinese Spring' (CS), and the difference became clearer after the long-term cold acclimation. To understand the molecular basis of this cultivar difference, we isolated two CBF/DREB1 homologs, Wcbf2, which are the candidate gene for a transcription factor of the Cor/Lea genes. Expression of the Wcbf2 gene was induced rapidly by low temperature (LT) and drought but not by abscisic acid (ABA). The gene expression was temporal and at least twice up-regulated by LT. The first up-regulation occurred within 1-4 h, which might correspond to the rapid response to LT, while the second up-regulation occurred during 2-3 weeks of cold acclimation. After the second up-regulation, the amount of Wcbf2 transcript greatly decreased in CS, while it increased again in M808 after 4 weeks until 9 weeks (end of the test period). The maintenance of this high level of the Wcbf2 transcript might represent the long-term effect of cold acclimation. The activation of Cor/Lea genes followed the accumulation of Wcbf2 transcript suggested direct involvement of the Wcbf2 gene in the induction and enhancement of the Cor/Lea gene expression. The cultivar difference in freezing tolerance developed during different stages of cold acclimation can be at least partly explained by the differential and coordinated regulation of the predicted Cor/Lea gene signal transduction pathway that is mediated by the CBF/DREB1 transcription factors in common wheat.

Acclimatization↗

PubMed2002

Cloning of cold-active alkaline phosphatase gene of a psychrophile, Shewanella sp., and expression of the recombinant enzyme.

A psychrophilic alkaline phosphatase (EC 3.1.3.1) from Shewanella sp. is a cold-active enzyme that has high catalytic activity at low temperature [Ishida et al. (1998) Biosci. Biotechnol. Biochem., 62, 2246-2250]. Here, we identified the nucleotide sequence of a gene encoding the enzyme after cloning with the polymerase chain reaction (PCR) and inverted PCR techniques. The deduced amino acid sequence of the enzyme contained conserved amino acids found among mesophilic alkaline phosphatases and showed some structural characteristics including a high content of hydrophobic amino acid residues and the lack of single alpha-helix compared with the alkaline phosphatase of Escherichia coli, which were possibly efficient for catalytic reaction at low temperatures. The recombinant enzyme expressed in E. coli was purified to homogeneity with the molecular mass of 41 kDa. The recombinant enzyme had a specific activity of 1,500 units/mg and had high catalytic activity at low temperatures.

Alkaline Phosphatase↗

PubMed1984

[Population structure of the forest Nentsi. IV. Immunoglobulin allotypes and the concentration and origin of Gm haplotypes with a null expression of the C gammal gene].

Serum blood samples from 796 of the total 1600 Forest Nentsi, the members of the isolate in the north-western part of Siberia were tested for the G1m (z, a, x, f), G2m (n), G3m (g, b0, b1, b3, b5, s, t) and Km (1) antigens. Significant heterogeneity in local Gm haplotype and Km1 allele frequencies has been found. The frequencies of "deleted" Gm (-; n; b) and Gm (-;..; g) haplotypes were found to be equal 0,020 and 0,004, respectively. When segregation disturbances for the Gm locus were inspected in 102 families, no apparent deviations from Mendelian expectations occurred. Blent, Oriental-Caucasian origin of Forest Nentsi has been confirmed by the presence of "Northern Oriental" Gm (za; b035st) and "Caucasian" Gm (f; b0135) markers showing the frequency of 0.199 and 136, respectively.

Arctic Regions↗

PubMed1986

The effect of interchain disulfide bond cleavage on the cold induced precipitation of cryoimmunoglobulins.

Selective cleavage of the interchain disulfide bonds present in the two IgG1-kappa monoclonal cryoglobulins Ger and Muk results in a partial loss of cryoprecipitability of the parent proteins at 0 degree C. The progressive loss of cryoprecipitability which occurs as a function of increasing reductant concentration parallels the successive cleavage of interheavy-light and interheavy-heavy chain disulfides. Circular dichroism shows that reduction and alkylation of hinge region disulfides induces small conformational changes in the IgG molecules that could alter cryoprecipitability. The N-terminal amino acid sequence of the Fc component derived by restricted proteolysis with trypsin of protein Muk was found to be completely homologous with N-terminal Fc sequences of noncryoglobulin IgG reference proteins, indicating identical hinge regions. Reduction and alkylation of two monoclonal IgM cryoglobulins also reduces cryoprecipitability. After reduction and alkylation of either the monoclonal IgM rheumatoid factor or the polyclonal IgG component of two mixed cryoglobulins recombination results in decreased cryoprecipitation of the intact cryoglobulin complex. In all cases inhibition of cryoprecipitation is greater when iodoacetic acid rather than iodoacetamide is employed as the S-alkylating group. These results do not support a direct role for the hinge region in the precipitation of cryoimmunoglobulins.

Alkylation↗

PubMed1998

Eotaxin and capping protein in experimental vasculopathy.

Ischemia-induced tissue activation may contribute to the pathogenesis of graft vasculopathy, but the mediators implicated have only partially been characterized. To gain further insight into the molecular mechanisms involved, syngeneic rat aortic transplants with cold-storage-induced vasculopathy were studied for differentially expressed mRNA transcripts. Vessel segments were exposed to either 1 or 18 hours of cold ischemia, followed by transplantation into syngeneic recipients. After 3 days or 4 weeks, the grafts were removed and total mRNA was isolated and used for differential display to identify modulation of transcript expression related to prolonged storage. Using 15 sets of random primers, 17 polymerase chain reaction products were up-regulated and 2 were downregulated in grafts exposed to 18 hours of ischemia. Sequencing of these amplicons showed that 6 had a high degree of homology to known sequences whereas 13 had no homology to any of the genes in the database. Two of the differentially displayed amplicons (capping protein and eotaxin) were cloned, re-amplified, and used as probes for Northern blot analysis to confirm their differential expression. Immunohistochemistry using monoclonal antibodies against capping protein-alpha and eotaxin confirmed that both proteins are expressed in the media of normal aortas and that there was an increased expression in vessels exposed to prolonged ischemia albeit that the increase at the protein level seemed less compared with changes in transcript expression. Northern blots with RNA from aortic allografts exposed to prolonged ischemic storage also showed increased levels of capping protein and eotaxin mRNA whereas there was a decrease in the relative amount of these transcripts in vessels exposed to balloon denudation, suggesting that the increase after prolonged ischemic exposure is not the result of a nonspecific response to injury. Based on the biological characteristics of capping protein and eotaxin it is conceivable that they play a pathogenetic role in ischemia-induced vessel wall remodeling. It remains to be established whether these genes or their products serve as target molecules for therapeutic interventions to prevent or treat cold-storage-induced graft vasculopathy.

Actin Depolymerizing Factors↗