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At least 19 recordsLinked to original sources
PubMed1978

Flash-induced changes in the in vivo bacteriochlorophyll fluorescence yield at low temperatures and low redox potentials in carotenoid-containing strains of photosynthetic bacteria.

The changes in the in vivo bacteriochlorophyll fluorescence induced by a Xenon flash at low temperatures (77--200 K) with the "primary" acceptor X chemically prereduced have been examined in whole cells of several species of photosynthetic bacteria which contain carotenoids absorbing in the visible part of the absorption spectrum. Two groups of species with different behaviour could be distinguished. In both cases a flash-induced rise of the fluorescence yield was observed with X prereduced at 77 k; as the temperature was increased the ratio of the maximum fluorescence (FM) and the basal fluorescence (F0) decreased and the kinetics of the decay of the high fluorescent state, as observed during the tail of the flash, apparently accelerated. Of the species examined the flash-induced changes in fluorescence-yield kinetics appeared to occur at higher temperatures in the members of one group (Chromatium vinosum, Rhodopseudomonas gelatinosa and Rhodopseudomonas palustris) than in the members of the other (Rhodopseudomonas palustris) than in the members of the other (Rhodopseudomonas sphaeroides and Rhodospirillum rubrum). These effects are interpreted in terms of the light-induced generation of triplet states within the reaction centre. It is suggested that the species-dependent differences may reflect differences in the molecular organisation of the reaction centre. It was found that in all species the reaction centre carotenoid triplet does not act as a fluorescence quencher under these conditions.

Bacteriochlorophylls↗
PubMed2025

Construction of cDNA library of Dalbergia odorifera induced by low temperature stress and screening of low temperature tolerant genes.

To systematically analyze the gene function of Dalbergia odorifera, the seedlings of D. odorifera were treated with low-temperature stress for 6 h. Total RNA was extracted from a mixture of seedling roots, stems, and leaves, and a low-temperature-induced D. odorifera yeast cDNA expression library was constructed. The library volume was 1.032 × 108 CFU, and the PCR (Polymerase Chain Reaction) identification of the library bacterial fluid showed that the amplification was around 1000 bp, with a single randomly distributed band, indicating that the library had been recombinantly inserted into the pYES2 vector. The GO (Gene Ontology) analysis showed that the library genes were mainly involved in metabolic and stress signaling pathways. The KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway enrichment analysis showed that the genes were primarily related to energy and metabolic pathways. Twenty-one genes were screened or obtained at -20°C for low-temperature tolerance. In addition, the organ expression profiles of the candidate genes were analyzed based on RNA-seq data, and the expression profiles of the candidate genes under low-temperature stress were also examined. The construction of the yeast library provides genetic resources for the analysis of the mechanism of low-temperature tolerance of D. odorifera, which is important for comprehending and utilizing the genetic resources of D. odorifera.

Gene Library↗
PubMed1976

Identification of PCB's in the presence of DDT-type compounds using low temperature luminescence.

Low temperature (77 degrees K) luminescence spectra of polychlorinated biphenyls (PCB's), DDT-type compounds and mixtures suggest a simplified method for identification and quantitation of aromatic pesticides with minimal prior sample treatment. Spectral differences allow identification of PCB's in the presence of DDT and the converse. Approximate detection limits, possible interferences and suggestions for further work are discussed

Cyclohexanes↗
PubMed2025

The SlWRKY39-SlZF61 module synergistically regulates SlGSTU42 to enhance low-temperature tolerance in tomato.

Low-temperature stress affects plant growth, and WRKY transcription factors alleviate such damage by regulating downstream genes. This study found that tomato SlWRKY39 significantly responds to low temperatures: its overexpression enhances seedling low-temperature tolerance by promoting ROS scavenging, while knockout exacerbates ROS accumulation and increases sensitivity to low temperatures. Transcriptome analysis indicated induction of glutathione metabolic pathway genes in slwrky39 plants under low-temperature stress. Y1H, EMSA, and Dual-LUC experiments confirmed that SlWRKY39 specifically binds to and activates the SlGSTU42 promoter; silencing SlGSTU42 attenuated the low-temperature tolerance conferred by SlWRKY39 overexpression, verifying that SlWRKY39 improves low-temperature tolerance via direct regulation of SlGSTU42. Additionally, SlZF61 interacts with SlWRKY39, enhancing its regulatory effect on SlGSTU42. SlZF61 overexpression strengthens low-temperature tolerance, while knockout increases sensitivity to low temperatures. In summary, under low-temperature stress, SlWRKY39 and SlZF61 are upregulated expression in tomato; SlWRKY39 binds to the SlGSTU42 promoter, and SlZF61 interacts with SlWRKY39 to form a protein complex, enhancing this binding. They synergistically activate SlGSTU42 transcription, thereby improving seedling low-temperature tolerance by scavenging ROS. This coordinated regulatory mechanism provides a new theoretical basis and practical insights for enhancing tomato low-temperature tolerance and ensuring stable production under low-temperature stress conditions.

Solanum lycopersicum↗
PubMed1978

Low temperature scanning electron microscopy: a review.

Low temperature scanning electron microscopy is useful for morphological and analytical studies both in situations where low temperature techniques are used during specimen preparation and where low temperature stages are used for specimen examination and analysis. Examples are given of different low temperature specimen preparation techniques and how they may be applied to different types of specimen. There are still a number of problems associated with morphological identification in fully frozen-hydrated samples and it is important to carry out parallel studies using more conventional transmission electron microscopy and light microscopy preparation techniques. A number of criteria are presented, some or all of which may be used to establish the existence of the frozen-hydrated state.

Animals↗
PubMed1979

[Studies on medico-legal diagnosis in cold district. 2. Cadaveric phenomena in low temperature surroundings (author's transl)].

The authors have investigated 14 kinds of findings of 15 cadavers in low temperature surroundings which had remained at known postmortem interval and had been subjected to medico-legal autopsies in our laboratory, comparing with those at normal temperature. In low temperature surroundings, the onset and progress of the findings due to autolysis or putrefaction are retarded in a marked degree but the turbidity of the cornea which is considered to be due to physical or chemico-physical phenomenon is retarded merely in a slight degree. Hence, an erroneous determination of the postmortem interval can be avoided by taking care of the peculiarity. Even the cadavers at low temperature display in 3 to 5 months after death the findings whose degrees correspond to those of the cadavers at normal temperature in 4 to 7 days after death. Some fly-larvae pass the winter on cadavers demonstrating that the time of death was towards the end of autumn of the preceding year.

Adolescent↗
PubMed2026

Uncovering molecular regulatory networks of low-temperature stress response in Trachinotus ovatus via integrated transcriptome and metabolome analyses.

Golden pompano (Trachinotus ovatus) is one of the most economically important marine fish species in China. It is susceptible to low-temperature stress, which significantly challenges its production and supply. Nevertheless, study on the regulatory mechanisms underlying low-temperature stress responses in golden pompano remains limited. Here, we firstly performed a time-series transcriptome analysis to reconstruct dynamic response patterns under low-temperature stress in golden pompano. Transcriptome profiling identified common differentially expressed genes (DEGs), including fos, hlf, and hmgb1, as well as condition-specific DEGs across distinct low-temperature stress groups. Based on cluster analysis, all DEGs were classified into five distinct expression patterns, reflecting diversified regulation of expression in golden pompano during low-temperature stress. Furthermore, condition-specific regulatory modules were explored via weighted gene co-expression network analysis (WGCNA), highlighting that the two module hub genes, serbf2 and lipc, might respond to low-temperature stress by regulating the lipid catabolic process. Subsequently, untargeted metabolomic analysis revealed that glycerophospholipid metabolism was a significantly enriched common pathway, highlighting its crucial role in mediating the response to low-temperature stress. Finally, by integrating transcriptomic and metabolomic analyses, a gene-metabolite interaction network associated with glycerophospholipid metabolism under low-temperature stress was established. These findings underscore the significance of multiple candidate genes and glycerophospholipid metabolism in golden pompano's response to low-temperature stress, thereby laying a solid molecular foundation for the development of low-temperature-tolerant fish strains.

Animals↗
PubMed1978

Low temperature microspectrofluorometry: design of a 'cold chamber'.

Low temperature microspectrofluorometry allows an improvement of spectral resolution and an increase of fluorescence intensity. Suppression of fluorescence fading, or at least a marked reduction, is also obtained. A cooling chamber for microspectrofluorometric measurement is described which allows the cooling, under a microscope, of a biological sample down to liquid nitrogen temperature. Objectives with numerical apertures better than 1.0 and a magnification power up to 100X can be used. Low temperature measurements on a histological sample are presented and discussed.

Bacillus cereus↗
PubMed2026

A novel urease-producing strain effectively induces cadmium biomineralization under low-temperature stress.

Microbially induced carbonate precipitation (MICP) has been widely used to immobilize Cadmium (Cd) in contaminated soils in mining-affected regions. However, its remediation efficacy under low-temperature stress, as well as the nucleation process that regulates Cd biomineralization via carbonate precipitation by psychrophilic bacteria, has yet to be investigated. Here, we isolated Pseudomonas sp. J-6, a novel urease-producing strain from tailings in high-altitude cold regions, exhibiting unparalleled cold adaptability at 5 °C and achieving 95.85 % Cd removal efficiency by MICP at 10 °C. Furthermore, the coprecipitation process of Ca1-xCdxCO3 was clarified through the continuous observation of the precipitates after the low-temperature MICP reaction. The crystal morphology transitioned from loose vaterite in the early stage to a dense square-block morphology in the middle stage. Cd2+ progressively shifted from a surface-bound state to lattice incorporation, ultimately resulting in the formation of stable Cd-substituted calcite crystals. In this process, low temperatures led to the formation of larger, highly ordered Cd-substituted calcite crystals, thereby strengthening Cd sequestration and its long-term stability. In addition, under low-temperature stress, Pseudomonas sp. J-6 induced MICP reaction decreased the bioavailable Cd in alpine slag soil by 44.85 % and enhanced physical properties. In the freeze-thaw cycles, the remediation efficiency remained stable. This study clarified the biomineralization potential in high-altitude cryogenic environments and the nucleation process of Cd biomineralization by psychrophilic bacteria-induced carbonate precipitation, filling a critical research gap in its application under extreme conditions and highlighting its promise for sustainable remediation of heavy metal pollution under low-temperature stress.

Cadmium↗
PubMed1976

Metabolic consequences of low-temperature kidney preservation.

The metabolic consequences of low-temperature kidney preservation were investigated. A comparison was made between kidneys which were immediately preserved and kidneys which had been ischemic for 1 hour. Two types of preservation techniques were used: (1) continuous perfusion with oxygenated plasma as described by Belzer and (2) a single flush with potassium-containing perfusate as suggested by Collins. Slices of renal cortex were removed at varying times during preservation and analyzed for a variety of metabolic intermediates. ATP levels were markedly reduced from normal. The Belzer technique was associated with higher ATP levels and ischemia lowered the ATP level. Kidneys perfused by the Belzer technique had lower ADP levels than those by the Collins method. Preservation caused marked elevation of tissue lactate, irrespective of ischemia or the technique used. We conclude that low temperature kidney preservation has profound effects on cellular metabolism. Therefore, the measurement of metabolic intermediates may provide a rational approach to the prediction of organ survival.

Adenine Nucleotides↗
PubMed2026

The Absence of E. coli Nucleoid-Associated Protein FIS at Low Temperature Leads to an Adaptation Response That Causes a Shift Towards Genome Compaction in Small Rods.

In contrast to the rod shape at 37°C, the morphology of Escherichia coli cells at temperatures just above the minimum temperature of growth is small rods. A study was initiated to determine the requirement of nucleoid-associated protein FIS for growth and genome compaction in the small rods at low temperature. Growth and nucleoid staining analyses revealed that the fis null mutant displayed decreased growth and initially formed filaments containing decondensed nucleoids at 12°C, indicating that FIS facilitates production of small rods with condensed nucleoids at low temperature. However, characterized by biphasic growth at low temperature, the fis null mutant exhibited increased growth, cell division, and nucleoid condensation following an acclimation phase. Therefore, the absence of FIS with nucleoid decondensation leads to an adaptation mechanism, termed FIS Null Adaptation Response, that causes a shift towards nucleoid condensation resulting in genome compaction in small rods. Furthermore, overproduction of the HsIVU protease suppressed the cold-sensitive phenotypes of the fis null mutant indicating that degradation of a natural substrate of the protease alleviates the requirement of FIS at low temperature. In addition, null mutations of genes encoding natural substrates of HsIVU (exoribonuclease RNAse R, and cell division inhibitor SulA) were identified as extragenic suppressors of the fis null mutation.

Escherichia coli↗
PubMed1979

Enzyme immobilization by radiation-induced polymerization of 2-hydroxyethyl methacrylate at low temperatures.

Enzyme immobilization by radiation-induced polymerization of hydrophilic glass-forming monomers, such as 2-hydroxyethyl methacrylate, was studied. Enzyme radiation damage could be sufficiently retarded at low temperatures. The immobilized enzyme activity yield was markedly higher at low temperature than at higher temperature polymerization. At low temperatures the polymerized composite had a porous structure owing to ice crystallization which depends on the monomer concentration. It was deduced that the enzyme was partially trapped on the polymer surface, partially isolated in the pore, and partially occluded inside the polymer matrix. A decrease in activity caused by enzyme leakage was observed with repeated use in enzyme reactions where the composites had a large porosity. The activity yield showed a maximum at certain optimum porosities, i.e., at optimum monomer concentrations. Continuous enzyme reaction was preferably carried out using immobilized enzyme columns.

Acrylates↗
PubMed1976

Studies on new process procedures in plasma fractionation on an industrial scale. I. Determination of the pH value of ethanol containing protein solutions at low temperatures.

A suitable combined pH electode is evaluated which provides reproducible readings under the extreme conditions of the cold ethanol plasma fractionation procedure. Adequately reproducible correlations are found between the pH measurements in protein solutions with an ethanol content of up to 40% at temperatures as low as -8 degrees C and the determination in diluted samples at room temperature using the standard procedure.

Chemical Fractionation↗
PubMed1979

Role of proline isomerization in folding of ribonuclease A at low temperatures.

In unfolded RNase A there is an interconversion between slow-folding and fast-folding forms (U(S) right harpoon over left harpoon U(F)) that is known to show properties characteristic of proline isomerization in model peptides. Here, we accept the evidence that U(S) molecules contain nonnative proline isomers and we ask about the isomerization of these proline residues during folding. The U(S) right harpoon over left harpoon U(F) reaction in unfolded RNase A is used both to provide data on the kinetics of proline isomerization in the unfolded protein and as the basis of an assay for measuring proline isomerization during folding.The tyrosine-detected folding kinetics at low temperatures have been compared to those of proline isomerization in unfolded RNase A. The comparison is based on the recent observation that the U(S) right harpoon over left harpoon U(F) kinetics are independent of guanidinium chloride concentration, so that they can be extrapolated to low guanidinium chloride concentrations, at which folding takes place. At 0 degrees C the tyrosine-detected folding reaction is 100-fold faster than the conversion of U(S) to U(F) in unfolded RNase A. Consequently, the folding reaction is not rate-limited by proline isomerization as it occurs in unfolded RNase A. An assay is given for proline isomerization during folding. The principle is that native RNase A yields U(F) on unfolding, whereas protein molecules that still contain nonnative proline isomers yield U(S). Unfolding takes place at 0 degrees C, at which proline isomerization is slow compared to unfolding. This assay yields two important results: (i) The kinetics of proline isomerization during folding are substantially faster than in unfolded RNase A-e.g., 40-fold at 0 degrees C. The mechanism of the rate enhancement is unknown. (ii) At low temperatures (0-10 degrees C), and also in the presence of (NH(4))(2)SO(4), the tyrosine-detected folding reaction occurs before proline isomerization and yields a folded intermediate I(N) that is able to bind the specific inhibitor 2'-CMP. The results demonstrate that a folding intermediate is spectrally detectable when folding occurs at low temperatures. They suggest that low temperatures provide suitable conditions for determining the kinetic pathway of folding by characterizing folding intermediates.

Ammonium Sulfate↗
PubMed1977

Regulatory effect of temperature and antigen upon immunity in ectothermic vertebrates. II. Primary enhancement of anti-hapten antibody response at high and low temperatures.

Enhancement of primary anti-hapten antibody response was more efficient when carp were preimmunized with modified carrier, rather than with its native form, especially when they were challenged with a slightly substituted penicilloyl-BSA conjugate (Pen5 BSA). No significant enhancement was obtained when the fish were challenged with a heavy conjugate (Pen30 BSA). When fish kept at optimal temperature were preinjected with the modified carriers, rising titers of anti-hapten antibodies were obtained even when the fish were transferred to low temperature just before being challenged with Pen5 BSA. It was concluded that modified carriers are more efficient in enhancing the anti-hapten antibody response and light conjugates are needed to make the cell cooperation possible. It was also suggested that when helper memory cell maturation was allowed to develop at optimal conditions, both cell cooperation and antibody synthesis could occur at low temperatures.

Animals↗
PubMed1976

Amylase activity and stability at high and low temperature depending on calcium and other divalent cations.

Since the extracellular amylase from B. caldolyticus had been characterized as a Ca-dependent enzyme, we wanted to determine the function and specificity of this ion, and it's possible significance for the thermophilic properties of the enzyme. The first question concerned the substitution of Ca with regard to the activity at 70 C. Our data show that Sr or other divalent cations can only to a limited extent replace Ca, and that only in presence of Ca full activity can be achieved. When the majority of the binding sites of the subunits are occupied by cations other than Ca, an almost total loss of activity results. The reason for this kind of inactivation was found in the responsibility of Ca for the stability of the enzyme at high temperature. The omission of Ca then leads to an irreversible denaturation of the enzyme, so that after this kind of treatment no activity is detectable at either high or low temperature, which means that the amylase is not a thermostable enzyme in the classical sense. The stabilizing effect of Ca could not be substituted by any other of the cations tested. Experiments concerning the stability of the enzyme at various temperatures in absence of presence of Ca revealed that the enzyme is stable up to 55 C as long as trace amounts of Ca are available. If these are omitted by a chelator, the enzyme becomes unstable between 40 and 45 C. Experiments in which a certain protein concentration range was tested at 40 and 70 C with given concentrations of Ca showed that the stability, and with it the activity, at high temperature is directly related to the amount of Ca available: The more the Ca supply is limited, the less enzyme protein can be kept in the right configuration, and irreversibly denatures as a result. At low temperature, however, the enzyme becomes almost independent of Ca, and the small amounts necessary to obtain full activity can be replaced by other divalent cations. The main conclusions concerning the role of Ca are that at high temperatures it participates in achieving the correct configuration of the thermostable form of the enzyme, and that in this function it is irreplacable. At low temperature it acts as an unspecific cofactor. The other conclusion is that the amylase can exist either as a caldo-active, thermostable, Ca-dependent enzyme, or in a Ca-independent thermostable state with a lower activity.

Amylases↗