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PubMedDate not supplied

Determination of molecular orientational order in cold-stretched poly(p-phenylene vinylene) thin films by DECODER 13C NMR.

The properties of poly(p-phenylene vinylene) (PPV) films depend on the degree of orientational order present in the films. Recently, Dermaut et al. reported a novel cold-stretching technique (Macromolecules 33, 5634-5637 (2000)) in which chain alignment can be introduced into PPV precursor films by uniaxially stretching them prior to the thermal elimination reaction that forms PPV. The two-dimensional direction exchange with correlation for orientation-distribution evaluation and reconstruction (DECODER) 13C NMR technique was applied to both unstretched PPV films and PPV films that were uniaxially cold stretched to a draw ratio lambda = l/l0 = 5. The unstretched films were found to be moderately ordered, comprised of a component present at 80% with a Gaussian distribution of 60 degrees fwhm, while the remaining 20% is isotropically distributed. A distribution of 9 degrees +/- 3 degrees fwhm was measured by NMR in good agreement with IR dichroism measurements for the uniaxially cold-stretched films, establishing that a high degree of orientational order can be introduced by cold stretching PPV films.

Anisotropy↗

PubMed2002

Cold stress decreases the capacity for respiratory NADH oxidation in potato leaves.

Cold stress effects on the expression of genes for respiratory chain enzymes were investigated in potato (Solanum tuberosum L., cv. Desiree) leaves. The nda1 and ndb1 genes, homologues to genes encoding the non-proton-pumping respiratory chain NADH dehydrogenases of Escherichia coli and yeast, were compared to genes encoding catalytic subunits of the proton-pumping NADH dehydrogenase (complex I). Using a real-time PCR system, we demonstrate a specific and gradual decrease of the NDA1 transcript after exposing the plants to 5 degrees C. After 6 days of cold treatment the NDA1 transcript abundance is 10% of the original level. This decrease is accompanied by specific decreases of immunodetected NDA protein and internal rotenone-insensitive NADH oxidation in mitochondria isolated from cold-treated plants. The alternative oxidase is not cold-induced neither at the protein nor at the activity level. The results are discussed in relation to the recent finding that the nda1 gene expression is completely light-dependent.

Cold Temperature↗

PubMed1991

Effect of alcohols and other hypnotics in mice selected for differential sensitivity to hypothermic actions of ethanol.

Mice selectively bred for resistance (HOT) and sensitivity (COLD) to the hypothermic effect of an acute dose of ethanol were tested twice during the course of genetic selection for their hypothermic response to other alcohols and sedative hypnotics. The drugs administered were ethanol, propanol, n-butanol, t-butanol, pentanol, diazepam, phenobarbital, pentobarbital, methyprylon and ethchlorvynol, all of which have sedative effects on the central nervous system, and hydralazine, a peripheral vasodilator. All drugs decreased body temperature of both HOT and COLD mice. In mice selected for seven to nine generations, COLD mice were more sensitive than HOT mice to all sedative drugs. The longer-chain alcohols were more potent than ethanol in inducing hypothermia, but the magnitude of the response difference between HOT and COLD mice appeared to be smaller. The difference between HOT and COLD mice in hypothermic sensitivity to an acute dose of ethanol was greater after 11-15 generations of selection than after seven generations. Similarly, the differential effect of the other alcohols, phenobarbital, pentobarbital, and methyprylon, on HOT and COLD mice increased with more generations of selection but to a lesser extent than ethanol. These data demonstrate that selecting for sensitivity to acute ethanol hypothermia has produced mice that are also differentially sensitive to other sedative hypnotic agents. They also support the hypothesis that the drugs used in the present study share a common mechanism of action for inducing hypothermia, which may be regulated by a common set of genes.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcohols↗

PubMed1989

Multiple mutations in the variable region of the kappa light chains of three monoclonal human IgM with anti-myelin-associated glycoprotein activity.

Human monoclonal IgM having an antibody activity directed to myelin-associated glycoprotein have distinctive features. Amino-terminal sequence of light and heavy chains from 6 IgM kappa that we have previously studied indicated that heavy chains belong to the VHIII subgroup, whereas light chains belong to 3 different subgroups of variability (V kappa I 2, V kappa II 1, and V kappa IV 3). We report here the complete sequence of the variable domain of 3 L chains: 2 V kappa IV and 1 V kappa II subgroups. Strikingly an unusually high degree of mutations clustered in the complementarity-determining regions (CDR) 1 and CDR 3 was found and the variable regions were joined to three different JK segments. Amino acid substitutions did not yield similar sequence in the CDRs suggesting that the kappa chains had no predominant role in the unique binding activity of these IgM or alternatively they are directed against different epitopes. Data are consistent with the previously reported lack of easily demonstrated public idiotopes common to anti-myelin-associated glycoprotein IgM. The pathogenesis of these IgM autoantibodies is most likely different from that of previously studied monoclonal rheumatoid factors or cold agglutinins where a genetic restriction of L or H chains or both has been observed.

Amino Acid Sequence↗

PubMed1999

Erythropoiesis: Splenic Immunoglobulin Variable Region Genes Encoding Red Blood Cell Binding Fab Fragments in Autoimmune Hemolytic Anemia.

An absolute requirement for the V(H(4-34) ) immunoglobulin (Ig) variable (V) region heavy chain (V(H) ) gene has been demonstrated in pathogenic cold agglutinin autoantibodies. Investigation of IgG binding anti-Rhesus (Rh) alloantibodies provides further evidence of V gene restriction in red blood cell (RBC) binding antibodies and demonstrates that the V(H(4-34) ) gene used to form cold agglutinins may also encode RBC antibodies of varied specificities. We reasoned that a similar V gene restriction may be evident in the gene segments encoding IgG anti-RBC autoantibodies mediating autoimmune hemolytic anemia (AIHA). To further examine this question IgG Fab fragment phage display libraries were constructed from the spleen of a patient with AIHA. The index autoantibody appeared to have incomplete anti-C specificity and bound all panel RBCs except Rh null. The Fab fragment phage display libraries were therefore panned twice on CDE/CDe RBCs and binding phage were eluted. Binding of the phage displayed Fab fragments to RBCs was confirmed by immunoflourescence and flow cytometry. Specificity was confirmed by the absence of binding to Rh null cells, murine RBCs and to human peripheral blood lymphocytes. Molecular analysis of Ig V genes encoding the pan RBC binding Fab fragments revealed a relative V(H) gene restriction and evidence of somatic mutation. The V(H(3) ) family member V(H(26) ) was prominent in RBC binding Fabs. The V(H(3) ) family member hV3005 and the V(H(4) ) family DP-65 gene segments also encoded RBC binding Fabs. The J(H(4) ) gene segment was present in all binding clones. Varied kappa and lambda light chain (V(L) ) genes were identified by sequencing and no single light chain was prevalent. Three of the ten V(L) and two of the three V(H) identified by sequencing appeared to derive from germline genes previously noted to have RBC binding specificity. We conclude that splenic Ig V genes can encode pan RBC binding antibodies with specificities similar to autoantibodies found in AIHA and that V(H) gene segment utilization by these antibodies is derived from a limited pool of somatically mutated V(H) gene segments.

Journal Article↗

PubMed1998

Evaluation of finger skin temperature by cold provocation test for diagnosis of vibration induced white finger (VWF).

Clinical data of workers (40-69 yrs) operating chain saws for a ten-year period from 1986 to 1995 were analyzed to assess the evaluation standard of finger skin temperature for a cold provocation test (10 degrees C 10 min). Screening points of finger skin temperature for screening 191 workers with a vibration induced white finger (VWF) were obtained from receiver operating characteristic (ROC) curves. The screening points at 5 min and 10 min after a cold provocation were approximately equal to 50th percentiles of 217 workers with no symptoms (NS group). The screening points of recovery rates at 5 min and 10 min after a cold provocation almost agreed with 50th percentiles in NS group. A new evaluation standard was prepared in reference to these screening points and finger skin temperatures by fraction in NS group. The new one will be useful for the health care of workers operating vibrating tools under present working conditions.

Adult↗

PubMed2004

Changes in the endoplasmic reticulum lipid properties in response to low temperature in Brassica napus.

Cold is an abiotic stress known to induce changes in membrane lipid composition. However, there is only limited information on the differential reactivity to environmental temperature of distinct cellular compartments. Therefore, we focused our attention on the endoplasmic reticulum (ER) that was never studied in this respect in plants. The ER membranes of etiolated Brassica napus (oilseed rape) hypocotyls grown at low temperature (4 degrees C) has been shown to be enriched in polyunsaturated fatty acids and phosphatidylethanolamine (PtdEtn) compared to hypocotyls grown at 22 degrees C. Despite the significant changes in their lipid composition upon cold exposure, the ER membranes showed a very partial physico-chemical adaptation as determined by measurement of membrane fluidity parameters such as local microviscosity of acyl chains and lipid lateral diffusion. To investigate the implication of transcriptional regulations during cold acclimation, we compared the abundance of transcripts for genes related to the fatty acid and the phosphatidylcholine (PtdCho)/PtdEtn biosynthesis pathways between normal temperature (22 degrees C)-acclimated and cold temperature (4 degrees C)-treated seedlings, using heterologous cDNA-array technology based on the knowledge on the Arabidopsis genome. Our studies demonstrate that a putative stearoyl-ACP desaturase isogene (orthologous to At1g43800) was up-regulated in response to low temperature.

Adaptation, Physiological↗

PubMed1995

A novel positive selection for identifying cold-sensitive myosin II mutants in Dictyostelium.

We developed a positive selection for myosin heavy chain mutants in Dictyostelium. This selection is based on the fact that brief exposure to azide causes wild-type cells to release from the substrate, whereas myosin null cells remain adherent. This procedure assays myosin function on a time scale of minutes and has therefore allowed us to select rapid-onset cold-sensitive mutants after random chemical mutagenesis of Dictyostelium cells. We developed a rapid technique for determining which mutations lie in sequences of the myosin gene that encode the head (motor) domain and localized 27 of 34 mutants to this domain. We recovered the appropriate sequences from five of the mutants and demonstrated that they retain their cold-sensitive properties when expressed from extrachromosomal plasmids.

Animals↗

PubMed2006

Specific and nonspecific interactions in a molecule with flexible side chain: 2-phenylethanol and its 1:1 complex with argon studied by high-resolution UV spectroscopy.

Using high-resolution resonance-enhanced two-photon ionization spectroscopy in combination with genetic-algorithm-based computer-aided rotational fit analysis and ab initio quantum chemistry calculations we determined the conformational structure and transition moment orientation in 2-phenylethanol and its 1:1 clusters with argon. The results clearly demonstrate that the gauche structure of 2-phenylethanol, which is stabilized by the intramolecular pi-hydrogen bond between the folded side chain and the benzene ring, is the most abundant in the cold molecular beam. In this conformer the transition moment is rotated by 18 degrees from the short axis of the aromatic ring. Two distinct 1:1 complexes of 2-phenylethanol with argon in a cis- and trans-configuration with respect to the side chain have been found. Employing the Kraitchman [Am. J. Phys. 21, 17 (1953)] analysis we have found that the structure of the 2-phenylethanol moiety and the orientation of the transition moment do not change after the complexation with argon within the experimental accuracy. From the measured band intensities we conclude that in addition to the dispersion interaction of the argon atom with the aromatic ring a hydrogen-bond-type interaction with the terminal -OH group of the side chain stabilizes the cis-structure of the 1:1 complex of 2-phenylethanol with argon.

Journal Article↗

PubMed2003

Positive Darwinian selection operating on the immunoglobulin heavy chain of Antarctic fishes.

The cooling of the Southern Ocean to the freezing point of seawater (-1.9 degrees C) over the past 25 million years played a dominant selective role in the evolution of the Antarctic fish fauna. During this period, the perciform suborder Notothenioidei, which is largely endemic to the Antarctic, diversified and developed numerous cold-adapted characters. In this report, we provide compelling evidence that the immunoglobulin heavy chain (IgH) of the notothenioid fishes has undergone adaptive selection. Two and four IgH clones were isolated, respectively, from spleen cDNA libraries prepared from the Antarctic icefish Chaenocephalus aceratus and the yellowbelly rockcod Notothenia coriiceps. The transmembrane region of the membrane form of the rockcod IgM heavy chain was located at the end of the second constant (C(H)) domain, in contrast to other teleost IgMs in which the transmembrane region is located at the end of the third constant domain. Phylogenetic analyses of C(H) regions revealed that rates of nonsynonymous nucleotide substitution were higher than rates of synonymous nucleotide substitution. Many of the nonsynonymous substitutions introduced charge changes, consistent with positive Darwinian selection acting to adapt the structure of the notothenioid immunoglobulins. The rates of nonsynonymous nucleotide substitutions were higher than the rates of synonymous nucleotide substitutions in complementarity determining regions of variable regions, suggesting that diversity at antigen binding sites is enhanced by genomic and/or somatic selection. Results of Southern blot hybridization experiments were consistent with a translocon type of IgH gene organization reminiscent of bony fishes and tetrapods.

Adaptation, Physiological↗

PubMed1983

Determination of the release rate of aldehyde pheromones from insect lures by cold trapping and direct bioluminescence analysis.

A rapid and sensitive procedure for measuring the release rate of aldehyde pheromones from insect lures has been developed. Using cold traps to condense aldehydes released into an airstream, the amount of pheromone in the aqueous condensate could be directly analyzed using a luminescence assay based on the response of bacterial luciferase to long chain aldehydes. A high recovery (approximately 70%) of aldehyde pheromone in the cold trap was obtained even when amounts as low as 10 ng were released into the airstream. Trapping times as low as 5 min can be used and analysis requires only a few seconds after temperature equilibration of the sample. This approach was applied to measure the release rate of 11-tetradecenal from different spruce budworm lures as well as to demonstrate that the release of aldehyde from a lure containing [14C]-cis-9-hexadecenal correlated closely to the release rate of radioactive material.

Aldehydes↗

PubMed1976

Biosynthesis of fatty acids by the carp, Cyprinus carpio L., in relation to environmental temperature.

Incorporation in vivo of sodium 1-14C-acetate into different lipid classes and fatty acids of total lipids and phospholipids of warm adapted and cold adapted carp livers was studied at 5 C and 22 C, respectively. The fatty acid composition of total lipids and phospholipids was also determined. The level of long chain polyunsaturated fatty acids in both total lipid and phospholipid fraction was higher in cold adapted fish than in warm adapted ones. The distribution of radioactivity among different lipid classes depended only on the actual incorporation of the temperature history of the animals. Livers of fish incorporated a higher percentage of radioactivity into long chain polyunsaturated fatty acids of total lipids and phospholipids in 5 C than in 22 C. The distribution of radioactivity among different fatty acids was dependent on the experimental temperature rather than on the temperature to which the fish were adapted. The results suggest that fish are able to adjust the pattern of the biosynthesis of fatty acids very rapidly to the prevailing temperature and to assure by this way the proper physicochemical properties of their membranes. The possible mechanisms involved in this rapid response are discussed.

Acclimatization↗

PubMed1998

Two types of mRNA encoding myosin regulatory light chain in carp fast skeletal muscle differ in their 3' non-coding regions and expression patterns following temperature acclimation.

cDNA clones encoding the myosin regulatory light chain (RLC) were isolated from a cDNA library prepared from fast skeletal muscle of the carp Cyprinus carpio L. Two types of cDNA clone encoding carp RLC were found with identical deduced amino acid sequences. The two mRNAs differed in the number of polyadenylation signals prior to the poly(A) tail in the 3' non-coding region. The two mRNA species, with approximate sizes of 1.4 and 0.8 kilobases, were also observed in northern blot analysis. Carp were acclimated for a minimum of 5 weeks to either 10 degrees C or 30 degrees C (14h:10h light:dark photoperiod). The total levels of mRNA transcripts coding for the RLC and myosin heavy chain were, respectively, 3.3 and 3.9 times higher in cold-than in warm-acclimated fish. Differences in the levels of RLC in mRNA transcripts were largely due to the concentration of the 1.4 kilobase mRNA species.

Adaptation, Physiological↗

PubMed1975

The role of phospholipid acyl chains in the activation of mitochondrial ATPase complex.

1. The role of length and unsaturation of phospholipid acyl chains in the activation of ATPase complex was studied with synthetic phosphatidylcholines and a phospholipid-dependent preparation obtained after cholate-extraction of submitochondrial particles (Kagawa, Y. and Racker, E. (1966) J. Biol. Chem. 241, 2467--2474). 2. Micelle-forming, short-chain phosphatidylcholines produced activation only at critical micellar concentration. The reactivated complex was cold-stable but the oligomycin sensitivity was low. 3. Bilayer-forming saturated phosphatidylcholines produced activation which was maximal at 9 carbon atoms in each chain but decreased sharply as the chain-length was increased and essentially disappeared at 14 carbon atoms. By contrast the oligomycin-sensitivity increased with the increase in chain length. 4. Activation of ATPase complex reappeared when bilayers were formed with long-chain unsaturated phosphatidylcholines. The activity was oligomycin sensitive. Significant inhibition of activity was observed also after incorporation of cholesterol into the bilayers. 5. By contrast the activation induced by negatively charged liposomes of diacylphosphatidylglycerol was independent on acyl-chain composition and occurred at very low amounts of phospholipid. 6. The discontinuity in the Arrhenius plot of activity of the ATPase complex reactivated with saturated phospholipids was found at temperatures close to the gel-to-liquid crystalline transition of the lipid showing that the activity of ATPase complex was sensitive to the physical state of membrane phospholipids. 7. It is concluded that (a) reactivation of ATPase complex by isoelectric phospholipids is an interfacial activation, the minimum requirement for the lipid effect being micelle formation. (b) In order to gain the properties of the native complex a stable lamellar phase is needed. Both activity and oligomycin sensitivity are regulated by the chain length and degree of unsaturation of phospholipid acyl chains.

Adenosine Triphosphatases↗

PubMed1992

Novel long-chain anteiso-alkanes and anteiso-alkanoic acids in Antarctic rocks colonized by living and fossil cryptoendolithic microorganisms.

Saponified extracts of rock samples colonized by cryptoendolithic microbial communities from the McMurdo Dry Valleys of Southern Victoria Land, Antarctica, were separated into hydrocarbon and fatty acid fractions by silica gel column chromatography. Hydrocarbons and methyl esters of fatty acids were analyzed by capillary gas chromatography-mass spectrometry. Unusually, a suite of long-chain anteiso-alkanes (a-C20 to a-C30) and anteiso-alkanoic acids (a-C20 to a-C30) were detected in many samples, together with straight-chain, branched and/or cyclic and acyclic isoprenoid compounds. These novel compounds are probably derived from unidentified heterotrophic bacteria or symbiotic processes in a unique microbial community in the Antarctic cold desert and suggest the occurrence of a special biosynthetic pathway. Long-chain anteiso-alkanes are probably formed through microbial decarboxylation of corresponding anteiso-alkanoic acids. They may serve as new biomarkers in environmental and geochemical studies.

Alkanes↗

PubMed1995

Human herpesviruses 6 and 7 in salivary glands and shedding in saliva of healthy and human immunodeficiency virus positive individuals.

The presence of human herpesvirus 6 (HHV-6) and human herpesvirus 7 (HHV-7) was investigated by the polymerase chain reaction in saliva specimens from healthy persons, donors affected by common cold or recurrent aphthous ulceration (RAU), and human immunodeficiency virus (HIV) positive patients, and in salivary gland biopsies. The sensitivity of the technique made it possible to detect as few as 5-10 target molecules in 15 microliters of saliva. HHV-6 was present in 63% of salivary gland biopsies and in 3% of salivas from healthy persons. No significant difference in the presence of HHV-6 was detected in specimens from donors with common cold, RAU, or HIV-infected patients. HHV-7 was present in 75% of salivary glands and in 55% of salivas from healthy persons. HHV-7 was detected with similar frequency in salivas from donors with common cold or RAU. Salivas from HIV-infected patients harbored HHV-7 with higher frequency (81%) and increased viral load. These results show that salivary glands are a site of persistent infection for both HHV-6 and HHV-7. However, the two viruses seem to differ in their biological properties: 1) HHV-6 is rarely present in saliva in detectable amounts, while HHV-7 is frequently detected; and 2) immunosuppression by acquired immunodeficiency syndrome (AIDS) increases the frequency of detection and the viral load of HHV-7, but does not have a significant effect on HHV-6 shedding in saliva.

Base Sequence↗

PubMedDate not supplied

Phylogenetic diversity of dissimilatory sulfite reductase genes from deep-sea cold seep sediment.

The phylogenetic diversity of dissimilatory sulfite reductase (DSR, EC 1.8.99.3) alpha-subunit genes from a deep-sea cold seep was analyzed. Bulk genomic DNA was extracted from the cold seep sediment and used for amplification by polymerase chain reaction (PCR) of DSR alpha-subunit gene. Two sizes of PCR products, 1.4 kb (expected) and 1.3 kb (unexpected), were amplified. Sixteen clones of the 1.4-kb amplicons and 16 clones of 1.3-kb amplicons, a total of 32 clones, were obtained and grouped into operational DSR units (ODUs) based on restriction fragment length polymorphism (RFLP) by digestion with HaeIII and MboI. A total of 14 ODUs, i.e., 5 ODUs from 1.4-kb amplicon clones and 9 ODUs from 1.3-kb amplicon clones, were recovered. About 400 bp of the 5' ends of all the clones was sequenced and validated the RFLP-based ODU grouping. All the 5'-end 400-bp sequences of ODUs, even from the 1.3-kb amplicons, showed the characteristic DSR amino acid sequence motifs. The ODUs from 1.4-kb amplicons were closely related to the delta-Proteobacterial lineage with the DSR genes from epsilon-Proteobacterial epibionts of the hot vent worm Alvinella pompejana. The ODUs from 1.3-kb amplicons were mostly related to the unknown but possibly archaeal lineage. The diversity of the DSR genes may indicate the diversity of sulfate reducers in the seep sediment as well as the complexity of electron donors including methane.

Amino Acid Sequence↗

PubMed2004

Mapping of functional sites on the primary structure of the contractile tail sheath protein of bacteriophage T4 by mutation analysis.

In order to determine the functional roles of amino acid residues in gp18 (gp: gene product), the contractile tail sheath protein of bacteriophage T4, the mutation sites and amino acid replacements of available and newly created missense mutants with distinct phenotypes were determined. Amber mutants were also utilized for amino acid insertion by host amber suppressor cell strains. It was found that mutants that gave rise to a particular phenotype were mapped in a particular region along the polypeptide chain. Namely, all amino acid replacements in the cold-sensitive mutants (cs, which grows at 37 degrees C, but not at 25 degrees C) and the heat-sensitive mutant (hs, lose viability by incubation at 55 degrees C for 30 min) except for one hs mutant were mapped in a limited region in the C-terminal domain. On the other hand, all the temperature-sensitive mutants (ts, grow at 30 degrees C, but not at 42 degrees C) and carbowax mutants (CBW, can adsorb to the host bacterium in the presence of high concentrations of polyethylene glycol, where wild-type phage cannot) were mapped in the N-terminal protease-resistant domain, except for one ts mutant. The results suggested that the C-terminal region of gp18 is important for contraction and assembly, whereas the N-terminal protease-resistant domain constitutes the protruding part of the tail sheath.

Amino Acid Sequence↗