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At least 19 recordsLinked to original sources
PubMed2026

The effects of cold temperature on the development, microbiome, and transcriptome of the sea anemone Nematostella vectensis.

Thermal conditions impact essentially all aspects of the physiology for ectotherms. While the effects of high temperatures have been widely studied, cold temperature effects on aquatic invertebrates and their microbial communities have been poorly characterized. To determine the diverse effects of exposure to cold temperatures, we assessed acute and long-term impacts of ecologically relevant low temperatures on the development, microbiome, and gene expression of the sea anemone Nematostella vectensis. Two hours post fertilization, embryos were exposed to temperatures from 4°C to 35°C and development rate to the juvenile stage was quantified. We found temperature impacts the development rate of embryos, where lower temperatures extended development time and resulted in mortality below 10°C. For both microbiome and host transcriptomic responses, anemones were held at 20°C, 10°C, and 0°C and compared at 24 hours and 7 days. Extended exposures to colder temperatures caused restructuring of the host-associated microbiome, with the loss of common taxonomic groups from the class Bacteroidia and Bacilli. Lastly, cold stress induced significant changes in gene expression, which were more pronounced at the 10°C than 0°C but showed little change over time in each temperature. Interestingly, expression of genes associated with innate immunity were among the most differentially expressed genes including heat shock proteins and innate immune genes providing a potential host-imposed mechanism to explain the shift in the microbiome. Overall, cold temperatures have broad effects on many facets of this sea anemone and its microbial community and indicate the importance of cold temperature events when characterizing how ectotherms acclimate to thermal variation.

Animals↗
PubMed1976

Ventilatory and circulatory O2 convection at 4000 m in pigeon at neutral or cold temperature.

Awake domestic pigeons, either maintained at 22 degrees C (series I) or acutely exposed at 2 degrees C (series II), were studied in a hypobaric chamber at 140 m and at various stages during a 4-week exposure to 4000 m. Steady-state pulmonary ventilation (Vg) and breathing pattern (VT, fr), oxygen consumption (MO2), O2 concentrations and pressures in the arterial (a) and mixed venous blood (v), hematocrit (Ht) and acid-base status in arterial blood, systolic blood pressure and heart frequency (fH) were measured. From these data cardiac output (Vb) and stroke volume (Vs), ventilatory and circulatory requirements (Vg/MO2, Vb/MO2), extraction of O2 from inspired air (EgO2) and blood EbO2), and capacitance coefficient of blood for oxygen (betabo2) were calculated. At 140 m, by comparison with predicted values for mammals of same body weight, pigeons at 22 degrees C extracted more O2 from the inspired gas, with lower fR, larger VT, similar Vg; they extracted O2 from the blood like mammals, with lower fH, larger VS, greater Vb, similar betabO2=70 mumol-L-1-torr-1. Acute exposure to 2 degrees C provoked a two-fold increase in MO2 which was achieved by doubling Vg and increasing O2 extraction from the blood. At 4000 m, in both series, pigeons hyperventilated within the first 30 min, with a resultant hypocapnic alkalosis comparable to that in mammals. Further hyperventilation with consequent greater hypocapnia and increase of arterial PO2 was complete beyond 3 hr. After a few weeks, the pH remained 0.07 above control normoxic value, Ht increased from 45 to 52%, betabO2 reached about 172 mumol-L-1-torr-1. At 2 degrees C, Vb also increased, mainly due to tachycardia.

Acid-Base Equilibrium↗
PubMed1976

Metabolic adaptations in brown adipose tissue of the hamster in extreme ambient temperatures.

Cold acclimation caused the following changes in the brown adipose tissue (BAT) of the hamster: the relative weight of the tissue increased, it color darkened, the multilocular structure predominated, and tissue protein content increased while fat content decreased. There was also an increase in the mitochondrial protein content. Heat acclimation had the opposite effects, i.e., the color became lighter, total and mitochondrial protein decreased, fat content increased, and tissue structure was mostly unilocular. Accordingly, cold acclimation was accompanied by increased tissue respiration in the presence of chi-glycerophosphate (chi-GP) and succinate, whereas heat acclimation reduced the respiratory activity of the tissue with these substrates. Isolated BAT mitochondria from cold-acclimated animals increased activities of chi-GP and NADH oxidase, whereas the activities of succinic and cytochrome oxidases and the amount of mitochondrial cytochromes were unchanged. The effects of heat acclimation were more pronounced: there was a decrease in the activities of chi-GP, succinic, NADH, and cytochrome oxidases, as well as in the cytochrome a and a3 content. When respiration of tissue slices on succinate was compared to the maximal potential respiration, as measured with mitochondria disrupted by freezing and thawing, it was found that the relative activity (slices vs. disrupted mitochondria) was highest in cold-acclimated animals and decreased progressively with increasing acclimation temperatures. It is suggested that the differences in the apparent activity of the mitochondria were due to changes in the conformation of the mitochondria as a result of acclimation.

Acclimatization↗
PubMed1976

Effect of water temperature during cold exposure on thermogenic drinking in rats.

Availability of water at temperatures higher than ambient (15, 25, 35 degrees C) failed both to affect the ratio of water to food intake during exposure to cold air (5 degrees C) and to influence the thermogenic (postcold exposure) drinking response of rats which characteristically occurs immediately after removal from cold air. Thus, availability of warm water during exposure to cold appeared to have no influence on cold-induced dehydration in rats. A specially constructed drinking apparatus was used in this study. It was designed to maintain water at temperatures greater than ambient during exposure to cold. Details for construction of the apparatus are provided.

Animals↗
PubMed1977

Comparative studies of wild-type and 'cold-mutant' (temperature sensitive) influenza viruses: geneology of the matrix (M) and non-structural (NS) proteins in recombinant cold-adapted H3N2 viruses.

The matrix (M) protein of the H2N2 virus A/Ann Arbor/6/60 may be distinguished from M protein of several H3N2 viruses and A/New Jersey/76 (HSWINI) by SDS acrylamide gel electrophoresis using a discontinuous buffer system. The smallest RNA (RNA 8) of the A/Ann Arbor/6/60 virus may be distinguished from RNA 8 of several H3N2 viruses by acrylamide gel electrophoresis in 3% or 3-6% gels in the absence of urea, if electrophoresis is done at 30 to 36 degrees C or 20 degrees C respectively. Ten clones of conditionally-lethal temperature-sensitive (ts) mutants were studied, which derived their cold-adaption and ts genes from mutant A/Ann Arbor/6/60, and their haemagglutinin from the H3N2 virus A/Scotland/840/74. Each clone was found to derive its M protein from A/Ann Arbor/6/60 mutant, and its RNA 8 from A/Scotland/840/74. The only assignment of genes 7 and 8 consistent with these findings for the recombinants is that in each parent virus (and in the recombinants) gene 7 codes for M protein, and gene 8 for NS protein. Furthermore, it may be concluded from the results that the biologically important ts lesions in the A/Ann Arbor/6/60 mutant parent are not present in the NS gene. In addition to the recombinants of A/Ann Arbor/6/60 and A/Scotland/840/74, five independent ts/cold-adapted recombinants of A/Ann Arbor/6/60 mutant with H3N2 and HSWINI wild-type viruses were examined, and all were found to contain the M protein of the A/Ann Arbor/6/60 mutant parent. This is suggestive that M protein may be at least partially responsible for the cold-adaptation and/or ts properties of the A/Ann Arbor/6/60 mutant and the recombinants.

Adaptation, Biological↗
PubMed1977

Alcohol, respiration, skin and body temperature during cold water immersion.

Subjects who had not been exercising, were immersed for 20 min in water at 13 degrees C after ingestion of alcohol. During the immersion period, total ventilation, end-tidal PCO2, rectal temperature, aural temperature, and mean skin temperature were recorded. Control experiments were carried out at the same water temperature. Blood samples (3 ml), taken immediately before the immersion period, were analyzed by gas liquid chromatography. The mean blood alcohol level was 90+/-11.2 mg-(100 ml)-1. There was no significant difference in ventilatory responses, rectal temperatures, aural temperatures, or mean skin temperatures achieved during the two cold water immersions. It would appear that for a 20-min immersion at 13 degrees C, relatively high blood alcohol levels do not affect ventilatory responses or increase body heat losses.

Alcohol Drinking↗
PubMed1976

Chloroplastic proteins of wheat and rye grown at warm and cold-hardening temperatures.

Soluble proteins and membrane polypeptides were separated from chloroplasts isolated intact from a cultivar each of spring wheat, winter wheat, and more freeze-resistant rye, and changes in them associated with cold hardening were detected by means of polyacrylamide gel electrophoresis. No drastic changes in chloroplast membrane polypeptides occurred during growth at low temperatures in the three cultivars. However, subtle changes were evident in the soluble chloroplast protein fraction. In this fraction at least one varietal difference was discernable, yet all cultivars produced a new protein band of lowest mobility during growth at low temperatures. After the preparations were fractionated by Sephadex G-50 all unhardened plant material displayed two peaks in the region of the fraction I protein band, whereas all cold-hardening material displayed one peak. A different band of soluble protein was present only after cold hardening in Kharkov whear and Puma rye, and was not present in extracts from the cold-grown spring wheat.

Chloroplasts↗
PubMed1977

An improved HRP method for the study of central nervous connections.

The HRP tract-tracing method has been modified by the introduction of cryoprotective agents, thereby allowing the enzymatic reaction to take place at sub-zero temperatures. By using cold temperatures the enzymatic reaction can be better controlled, which in turn makes it possible to "push" the method to its maximum without obtaining excessive crystallization. The addition of antifreeze agents, however, changes the acid-base phenomena, which in turn have to be adjusted by the use of appropriate buffers. The overall result is a considerable increase in efficiency as compared with the commonly used HRP procedure.

Acid-Base Equilibrium↗
PubMed1976

Effect of chilling on the survival of Bacteroides fragilis.

Factors affecting the susceptibility of Bacteroides fragilis subsp. fragilis to low temperature were examined. Predetermined numbers of cells were spread on agar media or suspended in enriched Trypticase soy broth and exposed to low temperature under both aerobic and anaerobic conditions. Exposure of 18-h growth of a freshly isolated B. fragilis strain to 4 degrees C aerobically or anaerobically resulted in a loss of at least 50% viability after 12 h. B. fragilis cells in early growth (6 h) were more tolerant to exposure at 4 degrees C than older cells (18 h). When the freshly isolated strain was repeatedly subcultured in the laboratory it was uniformly more cold tolerant than fresh clinical isolates. The incorporation of 1.0 M sucrose and 5 mM magnesium chloride into liquid media partially alleviated the lethal effects of cold temperature on B. fragilis subsp. fragilis.

Aerobiosis↗
PubMed1976

Cold agglutinin disease.

Development of the Coombs test has led to rapid progress in the recognition of various autoimmune hemolytic anemias. Cold agglutinin disease, a relatively rare disorder, occurs in idiopathic and secondary forms, the latter often in association with diseases that alter the immune status. The higher the titer of cold agglutinin, the greater is the thermal range of its activity. One of the characteristic clinical manifestations of the disease is striking cyanosis in acral areas on exposure to cold, which abates quickly on warming. This parallels the accelerated hemolysis at cold temperatures, which is reversible as heat is applied. In some patients, however, the disease is covert and is discovered only incidentally. The report of such a case is included.

Aged↗
PubMed1976

Genetic recombination of Coprinus. V. Repair synthesis of deoxyribonucleic acid and its relation to meiotic recombination.

Repair synthesis of DNA per se at pachytene is not needed for commitment to meiotic recombination although it is a necessary event to follow. Recombination frequency is governed by the rate of nicking and the time in which unrepaired nicks are allowed to match and crossover. Cold treatment at pachytene prevented repair synthesis, hence open nicks were accumulated to match and crossover, and a 3-fold increase in recombination resulted. The kinetics of cold temperature effect followed a quadratic function as shown by a computer simulation which agreed with our experimental data (Lu, 1974b). High temperature did not change the rate of repair synthesis. It did cause an increased nicking which led to a twofold increase in recombination and which entailed a higher rate of recovery repair synthesis.

Agaricales↗
PubMed1978

Cryoactivation and tryptic activation of blood 'prorenin' in normal man and animals.

Plasma and serum of healthy subjects apparently contain a precursor form of renin, or 'prorenin,' which can be activated by the ice-cold temperature at which samples are customarily handled for prolonged periods in laboratories and blood banks. The effect of such prior cryoactivation for 9 days at 4 degrees C is to increase subsequent plasma renin activity (PRA) at 37 degrees C by 108 +/- 16.3% (mean +/- SE) over the nonactivated control value (P less than 0.001). At a lower temperature (-4 degrees C), the cryoactivation effect is considerably greater than at 4 degrees C. Cryoactivation is not obliterated by the prefreezing of plasma, or reduced by inclusion of bacteriostats. Nor is it attributable to any detectable reduction in angiotensinase activity. In rats, cryoactivation at 4 degrees C is much lower than in humans, suggesting a marked species difference either in prorenin concentration or in the rapidity of its spontaneous conversion after blood collection. Trypsin at near optimal concentrations also consistently activates human plasma prorenin, whether at 4, 23, or 37 degrees C indicating that cold is not an essential concomitant of tryptic activation. In excess, the magnitude of which varies among individuals, trypsin at first produces activation and later a decline in PRA, probably due to degradation of the reactants (prorenin, renin, angiotensinogen) and of the initial product (angiotensin I). The identity of angiotensin I in activated and control plasmas can be established by specific radioimmunoassay, and bioassay. Our data indicate that tryptic activation involves little direct production of angiotensin I but rather converts prorenin, thereby enhancing the angiotensin generating capacity of the plasma renin system itself. Tryptic activation in plasma of anaesthetized dogs is lower than in humans, but higher than in conscious or anaesthetized rabbits in whom the effect appears to be slight. In anaesthetized rats there is virtually no tryptic activation, which is in line with the results by cryoactivation. Since the renin--angiotensin systems of dogs, rabbits, and rats have been extensively studied in experimental models of human hypertension, these observed departures from human levels of cryoactivation and tryptic activation of prorenin deserve further investigation.

Adult↗
PubMed1978

Contribution of an electrogenic sodium pump to the membrane potential in the intestinal epithelial cell.

The transmural potential difference of isolated rat duodenum and the membrane potential of its epithelial cell were examined during changes of the ionic medium at both warm (31--35 degrees C) and cold temperatures (2--5 degrees C). In the range of low external K+ concentrations, cooling produced an immediate and reversible depolarization of the membrane potential (around -10 mV) greater than that estimated from a simple thermodynamic temperature effect (RT/F). Such a temperature sensitive component of the membrane potential at 31 degrees C was completely abolished by anoxia and serosal ouabain. Readmission of K+ to the bathing fluid of duodenum previously deprived of K+ and loaded by Na+ caused a remarkable transient hyperpolarization of the epithelial membrane, which was abolished by serosal ouabain. Decreases in the value of transmural potential difference were also produced by cooling, anoxia and serosal ouabain, but these were so small that concurrent changes in the membrane potential could be regarded as chiefly reflecting changes in the effective emf of the cell. Thus, an electrogenic Na+-K+ exchange pump located on the serosal membrane of the duodenal epithelial cells was shown to contribute significantly to the membrane potential under normal conditions (up to around -7 mV). The coupling ratio of Na+-efflux and K+-influx associated with this pump was estimated by the Mullins-Noda equation (1963) to be approximately 4:3 under the physiological steady-state conditions.

Animals↗
PubMed1977

Effect of epinephrine upon irreversible disposal and recycling of glucose in dogs.

Irreversible utilization and recycling of glucose during epinephrine-induced hyperglycemia were studied in adrenal-demedullated dogs exposed to neutral or cold ambient temperature. Whatever the ambient temperature, most of the extra glucose mobilized by epinephrine is recycled rather than irreversibly utilized by the peripheral tissue.

Adrenalectomy↗
PubMed1978

Microtubules in protozoan cells. III. Ultrastructural changes during disintegration and reformation of heliozoan microtubules.

In the heliozoan, Echinosphaerium nucleofilum strain MA, cold temperature (2 degrees C) induced axopodial retraction to about 36% of the initial length after 3 h. By electron microscopy, it was found that such axopodial shortening is accompanied by degradation of axonemal microtubules (25 nm in diameter), followed by the appearance of macrotubles (37 nm in diameter) and filamentous structures (14 nm in diameter) of a tubular and twisted appearance. All of these structures (microtubules, macrotubules and filamentous structures) were found to be depolymerized completely by applying 10 mM colchicine for 1-2 h, and to be replaced by regions with low electron density. Axopodial re-extension was induced rapidly by returning the cold-treated organisms to room temperature (20 degrees C). At a very early stage of axopodial re-extension, the filamentous structures were often observed to be continuous with the macrotubules. At a late stage of axopodial re-extension, the reforming axoneme was composed only of normal microtubules, while the macrotubules and filamentous structures had disappeared. On the basis of these results, the processes of disintegration and reformation of microtubules are discussed.

Animals↗