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PubMed1994

The effects of a 3-day increase of ambient temperature on body temperature and REM sleep in an animal model of depression.

This study examined the effects of elevated ambient temperature (Ta) on body temperature (Tb) and rapid eye movement (REM) sleep in depressed and control rats. Previous studies have shown that elevations of Ta to the rat's thermoneutral zone of 29 degrees C produced an increase of REM sleep in control rats. In this study, 15 male Sprague-Dawley rats, seven saline control rats (SAL) and eight rats that were classified as depressed according to the chlorimipramine model of depression (CLI rats), were implanted for continuous Tb and polysomnographic recording and were exposed to two Ta's, 22 degrees C and 29 degrees C. CLI and SAL rats had significantly more REM sleep and a lower body temperature at 29 degrees C than at 22 degrees C. At 22 degrees C, CLI rats had significantly more REM sleep during the light period and a higher Tb in the light and dark periods than SAL control rats. At 29 degrees C, there were no significant differences in REM sleep or in Tb between CLI and SAL rats. Because human endogenous depression is associated with abnormal REM sleep and an elevated nocturnal Tb, these results give further support for the validity of the CLI model of depression and provide insight into the relationships among Tb, Ta, REM sleep and depression.

Acclimatization↗
PubMed2001

Evolutionary adaptation to temperature. IX. Preadaptation to novel stressful environments of Escherichia coli adapted to high temperature.

Stressful environments may be considered as those that reduce fitness, sometimes due in part to the increased metabolic expenditure required to sustain life. Direct adaptation to a stressor is expected to increase fitness and reduce maintenance metabolism, with the latter leading to increased biomass production. In this study, we test the general hypothesis that such adaptation to one stressor can preadapt organisms to novel stressful environments. Six lines of Escherichia coli propagated for 2,000 generations at 41-42 degrees C (42 group), a stressful temperature, were compared to six control lines propagated for 2,000 generations at 37degrees C (37 group) and to the common ancestor of both groups. We assayed biovolume yield (a measure of growth efficiency) and competitive fitness in the 42 group's selective high temperature environment as well as five novel stressful environments-acid, alkali, ethanol, high osmolarity and peroxide. As previously reported, at high temperature the 42 group had both higher yield and fitness than the 37 group and ancestor. In the novel environments, the 42 group generally produced yields higher than the 37 group (and marginally higher than the ancestor), but we found no differences in competitive fitness among the 37 and 42 groups and the ancestor. We also found that the performance of lines within groups was not correlated across stressful environments for either yield or relative fitness. Because previous adaptation to one stressor did not improve our measure of Darwinian fitness in novel stressful environments, we conclude that the 42 group shows no useful pre-adaptation, or cross-tolerance, to these types of environments.

Adaptation, Physiological↗
PubMed1995

Sequential addition of temperature-sensitive missense mutations into the PB2 gene of influenza A transfectant viruses can effect an increase in temperature sensitivity and attenuation and permits the rational design of a genetically engineered live influenza A virus vaccine.

We have previously described a strategy for the recovery of a synthetic influenza A virus wild-type (wt) PB2 gene (derived from influenza A/Ann Arbor/6/60 [AA] virus) into an infectious virus. It was possible to introduce an attenuating temperature-sensitive (ts) mutation at amino acid residue 265 of the AA wt PB2 gene and to rescue this mutant gene into infectious virus. Application of this new technology to influenza A virus vaccine development requires that multiple attenuating mutations be introduced to achieve a satisfactorily attenuated virus that retains the attenuation (att) phenotype following replication in vivo. In this report, we demonstrate that putative ts mutations at amino acids 112, 556, and 658 each indeed specify the ts and att phenotypes. Each of these mutations was introduced into a cDNA copy of the AA mutant mt265 PB2 gene to produce three double-mutant PB2 genes, each of which was rescued into an infectious virus. In general, the double-mutant PB2 transfectant viruses were more ts and attenuated in the lower respiratory tracts of hamsters than the single-mutant transfectant viruses, and the ts phenotype of two of three double-mutant PB2 transfectant viruses was stable even after prolonged replication in the upper respiratory tracts of immunocompromised mice. Two triple-mutant PB2 transfectant viruses with three predicted amino acid substitutions resulting from five nucleotide substitutions in the cDNA were then generated. The triple-mutant PB2 transfectant viruses were more ts and more attenuated than the double-mutant PB2 transfectant viruses. These results indicate that sequential introduction of additional ts mutations into the PB2 gene can yield mutants that exhibit a stepwise increase in temperature sensitivity and attenuation compared with the preceding mutant(s) in the series. Furthermore, the level of temperature sensitivity of the transfectant viruses correlated significantly with the level of attenuation of these viruses in hamsters. Although the triple-mutant PB2 transfectant viruses were attenuated in hamsters, intranasal administration of these viruses elicited a vigorous serum hemagglutination-inhibiting antibody response, and this was associated with resistance of the lower respiratory tract to subsequent wt virus challenge. These observations suggest the feasibility of using PB2 reverse genetics to generate a live influenza A virus vaccine donor strain that contains three attenuating mutations in one gene. It is predicted that reassortant viruses derived from such a donor virus would have the properties of attenuation, genetic stability, immunogenicity, and protective efficacy against challenge with wt virus.

Animals↗
PubMed1995

Characterization of DNA synthesis and DNA-dependent ATPase activity at a restrictive temperature in temperature-sensitive tsFT848 cells with thermolabile DNA helicase B.

A temperature-sensitive mutant defective in DNA replication, tsFT848, was isolated from the mouse mammary carcinoma cell line FM3A. In mutant cells, the DNA-dependent ATPase activity of DNA helicase B, which is a major DNA-dependent ATPase in wild-type cells, decreased at the nonpermissive temperature of 39 degrees C. DNA synthesis in tsFT848 cells at the nonpermissive temperature was analyzed in detail. DNA synthesis measured by incorporation of [3H]thymidine decreased to about 50% and less than 10% of the initial level at 8 and 12 h, respectively. The decrease in the level of thymidine incorporation correlated with a decrease in the number of silver grains in individual nuclei but not with the number of cells with labeled nuclei. DNA fiber autoradiography revealed that the DNA chain elongation rate did not decrease even after an incubation for 10 h at 39 degrees C, suggesting that initiation of DNA replication at the origin of replicons is impaired in the mutant cells. The decrease in DNA-synthesizing ability coincided with a decrease in the level of the DNA-dependent ATPase activity of DNA helicase B. Partially purified DNA helicase B from tsFT848 cells was more heat sensitive than that from wild-type cells. Inactivation of DNA-dependent ATPase activity of DNA helicase B from mutant cells was considerably reduced by adding DNA to the medium used for preincubation, indicating that the DNA helicase of mutant cells is stabilized by binding to DNA.

Animals↗
PubMed1997

Incubation at the nonpermissive temperature induces deficiencies in UV resistance and mutagenesis in mouse mutant cells expressing a temperature-sensitive ubiquitin-activating enzyme (E1).

In temperature-sensitive (ts) mutants of mouse FM3A cells, the levels of mutagenesis and survival of cells treated with DNA-damaging agents have been difficult to assess because they are killed after their mutant phenotypes are expressed at the nonpermissive temperature. To avoid this difficulty, we incubated the ts mutant cells at the restrictive temperature, 39 degrees C, for only a limited period after inducing DNA damage. We used ts mutants defective in genes for ubiquitin-activating enzyme (E1), DNA polymerase alpha, and p34(cdc2) kinase. Whereas the latter two showed no effect, E1 mutants were sensitized remarkably to UV light if incubated at 39 degrees C for limited periods after UV exposure. Eighty-five percent of the sensitization occurred within the first 12 h of incubation at 39 degrees C, and more than 36 h at 39 degrees C did not produce any further sensitization. Moreover, while the 39 degrees C incubation gave E1 mutants a moderate spontaneous mutator phenotype, the same treatment significantly diminished the level of UV-induced 6-thioguanine resistance mutagenesis and extended the time necessary for expression of the mutation phenotype. These characteristics of E1 mutants are reminiscent of the defective DNA repair phenotypes of Saccharomyces cerevisiae rad6 mutants, which have defects in a ubiquitin-conjugating enzyme (E2), to which E1 is known to transfer ubiquitin. These results demonstrate the involvement of E1 in eukaryotic DNA repair and mutagenesis and provide the first direct evidence that the ubiquitin-conjugation system contributes to DNA repair in mammalian cells.

Animals↗
PubMed1989

Cell lines established by a temperature-sensitive simian virus 40 large-T-antigen gene are growth restricted at the nonpermissive temperature.

The thermolabile large T antigen, encoded by the simian virus 40 early-region mutant tsA58, was used to establish clonal cell lines derived from rat embryo fibroblasts. These cell lines grew continuously at the permissive temperature but upon shift-up to the nonpermissive temperature showed rapidly arrested growth. The growth arrest occurred in either the G1 or G2 phase of the cell cycle. After growth arrest, the cells remained metabolically active as assayed by general protein synthesis and the ability to exclude trypan blue. The inability of these cell lines to divide at the nonpermissive temperature was not readily complemented by the exogenous introduction of other nuclear oncogenes. This finding suggests that either these genes establish cells via different pathways or that immortalization by one oncogene results in a finely balanced cellular state which cannot be adequately complemented by another establishment gene.

Animals↗
PubMed1984

Differences in temperature dependence of muscle contractile properties and myofibrillar ATPase activity in a cold-temperature fish.

Single muscle fibres were isolated from the fast myotomal muscle of the teleost Myoxocephalus scorpius L. and chemically skinned with 1% Brij. Maximum Ca2+-activated force (P0) increased from 14.5 +/- 1.1 N cm-2 at 2 degrees C to 19.1 +/- 1.8 N cm-2 at 15 degrees C (mean +/- S.E.). Maximum contraction velocity was determined by Hill's slack-test method (V0) and by extrapolation from force-velocity (P-V) relationships (Vmax). There was a linear relation between log10 V0 and temperature below 15 degrees C (Q10 = 1.9, P less than 0.01). The force-velocity characteristics of the fibres were determined at 2 degrees C and 20 degrees C. Points below 0.6 P0 on the P-V curve could be fitted by a linear form of Hill's equation. Extrapolated Vmax values were 0.55 muscle lengths s-1 (L0 s-1) at 2 degrees C and 1.54 L0 s-1 at 20 degrees C. Curvature of the P-V relationship was independent of temperature. The Mg2+, Ca2+-ATPase activity of Triton-X 100 extracted myofibrils was determined under similar ionic conditions to those used in skinned fibre experiments. (Ionic strength 0.16 mmol l-1, pMgATP 2.5). A linear relationship between log10 ATPase and temperature was only obtained below 15 degrees C (P less than 0.001). Above 15 degrees C, the Q10 for ATPase decreased significantly. The Q10(0-15 degrees C) for ATPase activity (3.9) was significantly higher than for unloaded contraction velocity. Supercontraction of isolated myofibrils to very short sarcomere lengths and differences in the mechanical constraints for crossbridge cycling between the preparations probably account for the lack of proportionality between these two parameters.

Adenosine Triphosphatases↗
PubMed1991

Effects of temperature on the performance of finishing swine: II. Effects of a cold, diurnal temperature on average daily gain, feed intake, and feed efficiency.

Forty-eight crossbred barrows and gilts weighing 84.5 +/- .33 kg were used during two 21-d trials to investigate the effects of a cold, diurnal temperature (CD; -5.0 to 8.0 degrees C) compared with a constant, thermoneutral temperature (TN; 20 degrees C) and the effects of sex (barrows vs gilts) on performance. A second objective was to determine shrinkage as a result of a 24-h fast immediately after the 21-d study of hogs commingled vs those not commingled for both environmental treatments (CD vs TN). Pigs housed in the CD chamber gained 27.2% more slowly (P less than .001; 75 vs 1.03 kg/d) than those in the TN environment and consumed 5.7% more feed (P less than .05; 3.88 vs 3.67 kg/d). The lower ADG and higher feed intake (FI) exhibited by the CD pigs resulted in poorer (P less than .05) feed efficiency (F/G; 5.33 vs 3.73, respectively). A temperature x sex interaction occurred for ADG but not for FI or F/G. Twenty-four-hour shrink for the CD pigs was 16.4% less than for the TN pigs (3.72 vs 4.45%, respectively); however, commingling did not affect shrinkage.

Animals↗
PubMed1976

[Study of temperature-sensitive mutations in the virilis group of Drosophila. 4. Phenogenetics of a temperature-sensitive mutation affecting the development of imaginal discs in Drosophila virilis Sturt].

The phenogenetics of a new temperature-sensitive mutation diskless-ts (dl-ts, 2nd chromosome) has been studied in D. virilis. The rearing of larvae from the 1st instar at the temperature 31 degrees resulted in the complete or partial arrest of the development of imaginal discs and, consequently, the death of larvae prior to the pupation, at the prepupa stage. The change of temperature from 25 to 31 degrees during the second half of development in the 3rd instar affects the differentiation of imaginal discs. Some organs differentiate completely or partially (eyes, wings, legs) whereas the rest do not develop at all. The sensitive period embraces the whole larval development till the beginning of pupation.

Animals↗
PubMed1998

Effect of rearing at non-permissive temperature on silkworm larvae infected with temperature-sensitive lef-8 mutant of bombyx mori nucleopolyhedrovirus.

A temperature-sensitive (ts) mutant of bombyx mori nucleopolyhedrovirus (BmNPV), ts-S1, contains a mutation in a putative RNA polymerase gene, which is involved in late viral gene expression. When 4th-instar silkworm larvae were infected with 1.0 x 10(5) TCID50 of ts-S1 per larva and reared at 33 degrees C, the titre of budded virus (BV) and number of occlusion bodies (OBs) in the haemolymph of the infected larvae were very low in the early stage but markedly increased in the late stage of infection. In contrast, a rapid increase in both BV titre and OB number was detected in the haemolymph of infected larvae reared at 25 degrees C. LD50 values of ts-S1 and wild type BmNPV (wtBmNPV) for 4th-instar larvae were 2.41 and 0.96 TCID50 per larva at 25 degrees C, and > 1.0 x 10(6) and 1.70 TCID50 per larva at 33 degrees C, respectively. These results indicate that the virulence of ts-S1 for the larvae reared at 33 degrees C was markedly reduced. To examine further the reduction of ts-S1 virulence at the non-permissive temperature of 33 degrees C, silkworm larvae were infected with ts-S1 at the multiplicity of 1.0 x 10(2) - 1.0 x 10(6) TCID50 per larva, reared for various time at 33 degrees C and then shifted to 25 degrees C. Longer rearing periods at 33 degrees C resulted in better survival rates indicating that the reduction of virulence of ts-S1 was proportional to cumulative rearing time at 33 degrees C. When large virus inocula were used, a growth alteration of larvae was preferentially induced. However, when small virus inocula were used, the appearance of abortive infection due to the non-permissive temperature became more evident.

Animals↗
PubMed1997

[Determination of liquid-crystalline transition temperature of temperature-sensitive liposomes of futraful by 1HNMR].

1HNMR was employed to determine the liquid-crystalline transition temperature (TC) of the temperature-sensitive liposomes of futraful. It is a method with high sensitivity, high accuracy and furnishing more information. The 1HNMR spectra were made and studied. The rate of peak height increase of phospholipid correlates to the thermotropic phase transition of liposomes. The study shows that the TC of DPPC-liposomes and DSPC-liposomes is 36 degrees C and 48 degrees C, respectively. The TC of DPPC-DSPC-liposomes correlates with the proportion of the amount of DPPC and DSPC. The TC is not affected by futraful. The temperature-sensitive liposomes of futraful with TC of 41 degrees C were prepared which consisted of 60% DPPC and 40% DSPC.

Crystallins↗
PubMed2001

Photoperiod and temperature interactions regulate low-temperature-induced gene expression in barley.

Vernalization and photoperiod (PP) responses are developmental mechanisms that allow plants to synchronize their growth and reproductive cycles with the seasonal weather changes. Vernalization requirement has been shown to influence the length of time that low-temperature (LT)-induced genes are up-regulated when cereal species are exposed to acclimating temperatures. The objective of the present study was to determine whether expression of LT-induced Wcs and Wcor gene families is also developmentally regulated by PP response. The LT-tolerant, highly short-day (SD)-sensitive barley (Hordeum vulgare L. cv Dicktoo) was subjected to 8-h SD and 20-h long-day PPs at cold-acclimating temperatures over a period of 70 d. A delay in transition from the vegetative to the reproductive stage under SD resulted in an increased level and longer retention of LT tolerance. Similar WCS and WCOR protein homologs were expressed, but levels of expression were much higher in plants acclimated under SD, indicating that the poor LT tolerance of long-day plants was the result of an inability to maintain LT-induced genes in an up-regulated state. These observations indicate that the PP and vernalization genes influence the expression of LT-induced genes in cereals through separate pathways that eventually converge to activate genes controlling plant development. In both instances, the delay in the transition from the vegetative to the reproductive stage produces increased LT tolerance that is sustained for a longer period of time, indicating that the developmental genes determine the duration of expression of LT-induced structural genes.

Acclimatization↗
PubMed2004

Comparison of axillary temperature with rectal or oral temperature and determination of optimum placement time in children.

The present study was done to compare axillary temperature (AT) with rectal temperature (RT) in 100 infants and with oral temperature (OT) in 100 children agd 6 to 12 years and also to find out the optimum placement time of the mercury thermometer at the above sites. Simultaneous AT and RT recording was done in infants while sequential AT and OT recording was done in older children by different investigators using calibrated Hick thermometers. The placement time recorded was when 3 consecutive readings at one minute interval remained unchanged. Significant correlation was observed between RT and AT (r=0.95, p <0.01) and between OT & AT (r = 0.97, p 0 <0.01). Equations were derived to calculate RT & AT from AT. The mean placement time for RT, AT and OT was 2.3 minutes, 4.8 minutes and 3.1 minutes respectively. The study showed a high degree of correlation between OT or RT and AT.

Axilla↗
PubMed1992

[Temperature monitoring and sites of measurement of body temperature].

The authors report an investigation of 331 consecutive patients submitted to major surgery to evaluate the reliability of temperature monitoring in different body sites in relation to central temperature. After having considered the minimal temperature changes and the difficulties due to the different techniques used, it is concluded that the measurement at the middle 3rd of the oesophagus is the most reasonable measurements site.

Body Temperature↗
PubMed1991

[Only rectal temperature measurements are suitable for routine temperature measurement].

A new rapid electronic thermometer (V.C.T. TERUMO) has been introduced to Danish hospitals. Oral and rectal V.C.T. measurements were compared with rectal measurements with mercury thermometers. In addition, rectal V.C.T. measurements in the wards were compared with rectal measurements with mercury thermometers. A total of 91 patients participated in the investigation. The average differences between the electronic rectal and oral compared with recordings by mercury thermometers were found to be 0.02 degree C and 0.75 degree C, respectively, under optimal conditions for measurement while the corresponding scatters of difference in temperature were 0.17 degree C and 0.74 degree C, respectively. The average difference between rectal temperature measurements with mercury thermometers and rectal V.C.T. measurements carried out during daily routine circumstances was 0.08 degree C while the scatter of the difference in temperature was 0.26 degree C. It is concluded that rectal V.C.T. measurements are just as suitable as rectal measurements with mercury thermometers and employment of rectal V.C.T. thermometer measurements is recommended in the daily hospital routine. Employment of oral and axillary measurements is discussed and not recommended.

Adult↗
PubMed1991

[Temperature control of the crossing-over frequency in Drosophila melanogaster. Effect of infra- and super-optimal shock temperatures in early ontogenesis on the recombination frequency].

Effect of temperature shock treatments (0 and 37 degrees C) in early ontogenesis on recombination frequency was studied in two strains of Drosophila X1 and X2. Recombination frequency under treatment with temperature of 0 degrees C and 37 degrees C (shock treatment), as well as at 14 degrees C and 29 degrees C nonshock treatment was found to be dependent on strain genotype, the chromosomal segments under consideration, developmental stage and the age of individuals analysed. Shock treatments usually increase recombination frequency, whereas nonshock treatments lead to unstable and variable recombination frequencies. A concept of ontogenic homeostasis of recombination has been introduced. It is assumed that the effect of temperature treatments on recombination frequency is indirect--i.e. physiologically mediated.

Animals↗
PubMed1978

Regulation of herpes simplex virus type 1 DNA synthesis: temperature-shift studies with DNA-negative temperature-sensitive mutants.

The regulation of expression of viral genes involved in the synthesis of herpes simplex virus type 1 DNA was studied using three DNA- temperature-sensitive (ts) mutants (B, C, and D). These mutants were examined for their ability to synthesized viral DNA and polypeptides following temperature shift-down in the presence or absence of the transcription inhibitor actinomycin D. The results demonstrated that the B gene product is required transiently early in infection and apparently controls a transciptional step required for HSV DNA synthesis. The C gene product is required continuously during infection and also controls a transcriptional step needed for viral DNA synthesis. In contrast, the product of the D gene does not directly control a transcriptional step, is required continuously, appears to be directly involved in HSV DNA synthesis, and is probably the gene for viral DNA polymerase. The results further showed that recovery of viral DNA and polypeptide synthesis following temperature shift-down in the absence of inhibitor was greater for the D mutant than for the mutants blocked in viral DNA synthesis at the level of transcription.

DNA, Viral↗