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At least 19 recordsLinked to original sources
PubMed1992

Switches in fish myosin genes induced by environment temperature in muscle of the carp.

Fish are cold blooded animals and their muscle function is expected to be greatly affected by environmental temperature. Species that live in the Antarctic ocean have evolved a different contractile system to fish that live in the tropical waters. In the case of Antarctic fish they have a higher specific myofibrillar ATPase activity but 'the trade off' seems to be a lower thermal stability. They are thus capable of a greater muscle power output at low temperatures but the lower thermal stability means they are restricted to living at temperatures below +4 degrees C. Some species, however, experience a wide range of seasonal variations in temperature. We found that these species adapt by changing their myofibrillar apparatus so that they have a higher specific ATPase which physiological studies indicate is due to a different type of myosin crossbridge for low temperature swimming. This is reversible and they develop a contractile system with a greater thermal stability and a commensurate loss of ATPase activity when their environment warms up again. There were several possibilities by which this may be achieved including expression of different isoform genes or the post- translational processing of existing proteins. To elucidate the mechanism we made a carp genomic library and screened this for myosin heavy chain gene using mammalian cDNA sequences under moderate stringency conditions. The clones were restriction mapped which resulted in 28 non overlapping sequences. This indicated that the carp had a reasonably large family of myosin heavy chain genes that is about twice the size of that in mammals. Rather fortuitously the first sequence to be identified was from the gene that is predominantly expressed in white muscle at warm temperatures. This was done by extracting the RNA from red and white muscle of fish acclimated to different 25 degrees C, 18 degrees C or 8 degrees C and carrying out Northern analysis using the gene fragment as the probe. The time course for the expression of this gene when carp maintained at a low temperature were acclimated to a warm temperature was slightly in advance of the change in myofibrillar ATPase which suggested that this strategy for adaptation is regulated at the transcriptional level. Hence these species of fish can adapt to seasonal changes in temperature by expressing different myosin heavy chain isoform genes and rebuilding their myofibrils for either warm or cold temperature swimming. At the present time we are characterising the 5' regulatory (promoter) sequence of this gene to see how a temperature switch may operate.(ABSTRACT TRUNCATED AT 400 WORDS)

Adaptation, Physiological↗
PubMed1977

Metabolic effect of high environment temperature on non-diabetic and diabetic rats.

Blood lipids and glucose were studied in streptozotocin diabetic rats during hyperthermia. Blood glucose, free fatty acids (F.F.A.) and glycerol of diabetic rats with a rectal temperature of 42 degrees C (hyperthermic) were elevated significantly above those values found in normothermic (TR = 38 degrees C) diabetic or normothermic non-diabetic rats as well as hyperthermic non-diabetic rats. Streptozotocin diabetes caused an elevation in blood triglycerides of normothermic rats, but this hypertriglyceridemia was depressed in diabetic rats during hyperthermia. As in the case of diabetic animals, hyperthermia also caused a depression in the blood triglycerides of non-diabetic rats. However, unlike in the diabetic animals, the blood F.F.A. of non-diabetic rats were depressed during hyperthermia. Although hyperthermia caused a significant increase in the blood glucose of the diabetic animals, no significant change in blood glucose was shown in the hyperthermic non-diabetic rats. Blood cholesterol did not change significantly in the non-diabetic or diabetic animals during hyperthermia. The blood changes of these "energy substrates" are discussed with respect to their possible role in the extreme sensitivity of diabetics to high environmental temperature and "heat stress".

Animals↗
PubMed1978

Environment, temperature and death rates.

Analysis of recorded monthly deaths in England and Wales shows a close association of death rates with external temperature in most diseases other than the cancers. Analysis of daily deaths in England and Wales and in New York shows the following relationships between temperature and deaths from myocardial infarction, strokes and pneumonia. Between -10 degrees and +20 degrees C mimimum temperature there is a nearly linear fall in deaths as the temperature rises. Above 20 degrees C deaths rise steeply as the temperature rises and below -10 degrees C rise steeply as temperature falls. These associations of deaths with temperature are much stronger in the elderly than in younger subjects. Detailed analysis of the daily deaths in England and Wales from myocardial infarction, strokes and pneumonia show that short-term (1--2 days) temperature changes have little effect on death rates but medium-term (7--10 days) and longer-term (three or more weeks) changes associated with very significant changes in death rates. The three diseases vary in the time relations between temperature change and change in death rates. In all three there is an interval between the change in temperature and death and this is shortest in the case of myocardial infarction (1--2 days before death), longest in the case of pneumonia (about a week before death) and intermediate in the case of strokes (about 3--4 days before death). At low temperatures death rates increase as the duration of temperature change increases, while at high temperatures (but below +20 degrees C) death rates decrease as the period of temperature change is longer. The implications of these findings are discussed and it is postulated that there is probably causal relationship between temperature change and deaths from a wide variety of diseases. A proximal link in the chain is probably a failure of autonomic control of body temperature in the elderly leading to a change in body temperature and some humoral change which in turn leads to death. It is not appropriate to concentrate on hypothermia as the relationship between temperature and death is seen at all temperatures.

Age Factors↗
PubMed1992

Fast atom bombardment-mass spectrometry for bacterial chemotaxonomy: influence of culture age, growth temperature, gaseous environment and extraction technique.

Extracted phospholipids of Escherichia coli, Proteus mirabilis and Enterobacter cloacae were examined by fast atom bombardment-mass spectrometry which yielded major peaks between m/z 225 and 761. The result of extracting freeze-dried or 'wet' cells showed that freeze-drying may be omitted although weighing of dried cells offers a useful means of standardizing the extraction procedure. Anaerobic growth quantitatively altered the chemical finger-print as a result of increase in ratio of saturated: unsaturated carboxylic acids. Growth temperature also affected profiles over the temperature range 24-45 degrees C. A less drastic influence on mass spectra was culture age, over the range 16-48 h. Comparison of spectra was possible with Pearson's coefficient of linear correlation which yielded the following values: wet and lyophilized cells, r = 0.97; aerobic and anaerobic growth, r = 0.82; 24 degrees C and 45 degrees C, r = 0.76; 16 h and 48 h, r = 0.95. These results show that although quantitative differences do occur between spectra for the same organism prepared in different ways, they are less than interspecies variation, e.g. with E. coli and P. mirabilis, r = 0.46. Any differences which are due preparation method can be overcome by standardization of technique.

Aerobiosis↗
PubMed1978

Membrane properties of an extreme thermophile. II. Membrane functions underlying leucine transport and their relation with thermotropic phase transitions.

Various membrane properties of Thermus thermophilus HB8 were studied in order to elucidate the mechanism and implication of cell adaptation to a high temperature environment. 1. The profile of temperature dependence of the amino acid uptake rates was similar for the membrane obtained from cells grown at both 61 degrees C and 77 degrees C. 2. The remaining uptake activity after heat treatment paralleled the membrane potential generating ability, as measured by auramine O fluorescence response to the respiration substrate, and was not dependent on the growth temperature. 3. The temperature dependence of the efflux of the accumulated amino acid reflects the physical phase of the membrane and is dependent on the growth temperature.

Biological Transport↗
PubMed1979

Cells transformed by temperature-sensitive mutants of avian sarcoma virus cause tumors in vivo at permissive and nonpermissive temperatures.

Chick embryo (CE) fibroblasts and normal rat kidney (NRK) cells transformed by temperature-sensitive (ts) mutants of avian sarcoma virus (NY68, LA23, LA24, LA25, LA29, LA31, GI201, GI202, GI251, GI253 induce tumors on the chorioallantoic membrane (CAM) of chick eggs at temperatures that correspond to the permissive and nonpermissive temperatures used to induce conditional expression of the "transformed" phenotype in these cells when cultured in vitro. Chick embryo cells infected with transformation-defective mutants of ASV (td101, td108) or RAV-50 were nontumorigenic under the same conditions, as were nontransformed CE and NRK cells. This indicates that the CAM is not an unusually susceptible substrate for cell growth and that the ability of tsASV-transformed cells to form tumors at nonpermissive temperatures reflects their true tumorigenicity. In contrast, a ts mutant chemically transformed rat liver cell line, ts-223, only formed tumors on the CAM under permissive conditions. The wild-type parent cells (W-8) of this mutant produced tumors at both permissive and nonpermissive temperatures. Direct implantation of microprobe thermometers into tumors caused by ts-ASV-transformed cells at nonpermissive temperatures confirmed that tumor formation occurred in a stable temperature environment and was not due to temperature fluctuations which might have created semi-permissive conditions for tumor growth. Cells isolated from tumors formed at nonpermissive temperatures and recultured in vitro displayed temperature-dependent hexose transport and colony formation in agar similar to the orginal parent cell inoculum. Similarly, virus recovered from tumors at nonpermissive temperatures retained the ts mutation.

Alpharetrovirus↗
PubMed1977

Temperature effects on bacterial movement.

Details are presented for the construction of a simple precision temperature-controlled chamber for investigating bacterial motile behavior. Independent of original incubation temperature, all species of motile bacteria observed showed a five- to sevenfold increase in average translational velocity (micrometers per second) as the environment temperature was incremented over the range from 10 to 50 degrees C. Temperature jumps downward produced transient tumbling or reciprocal behavior responses, depending on the mode of flagellar distribution, in all species examined. Upward temperature jumps induced accelerated velocities without tumbling or reversal. A partial capacity adaptation to temperature was noted, in that the greatest average translational velocity at any given observation temperature occurred when the organisms were grown at temperatures less than the optimum.

Adaptation, Biological↗
PubMed1975

[Influence of mediopreoptic stimulation on temperature regulation in rats before and after serotonin injection].

The effects of electrical stimulation of the Area praceoptica medialis (APM) and intraventricular serotonine injection were investigated in thirty Wistar rats tested under normo-, hypo- and hyperthermic conditions. Temperature responses such as oxygen consumption and rectal temperature were measured and heat loss was calculated. The effects of the first stimulation before serotonine injection were compared with those of the second one after serotonine application in order to prove the influence of serotonine on temperature responses due to APM stimulation. On the other hand, the influence of stimulation on changes produced by serotonine injection should be shown by the recordings of the second serotonine responses with stimulation effects and by comparison of these with those of the first serotonine responses without stimulation effects. The first APM stimulation depending on the rectal temperature before stimulation resulted in decreasing oxygen consumption in hypothermic rats while increasing that of hyperthermic animals. There was a little decrease of rectal temperature under hyper- and normothermic conditions. while under hypothermic conditions animals showed marked depression. The increase in heat loss, however, was least in hyperthermic rats and most pronounced in hypothermic animals. The second APM stimulation did almost not affect the temperature responses after serotonine application in normothermic rats, while causing supercooling agin under hypothermic conditions and insignificant cooling at hyperthermic environment temperature. Comparison of the first and second stimulation effects revealed statistical significant differences at normo-, hypo- and hyperthermic temperatures. The results are discussed under consideration of the different starting conditions before the first and second stimulation. These findings do not indicate that serotonine would shift the sensibility of mediopraeoptic structures and thus unequivocally modifies stimulation effects.

Animals↗
PubMed1992

Oscillometry of radial artery in acrocyanosis and cold sensitivity.

Acrocyanosis is reassessed on the basis of 34 new patients with diagnostic clinical features. The most useful tests are the skin temperature differences (STD) between wrist and end of fingers (or ankle and end of toes) and oscillometry over the radial and dorsalis pedis and posterior tibial arteries. Capillaroscopy of the conjunctival and nailfold vessels is useful in half the patients. Capillary resistance was not helpful. STD of 1.5 degrees C or more between skin of wrist or ankle and fingertip or toetip, is usually associated with more severe disease and capillary abnormalities on microscopy, and with reduced oscillometry (to 1 or less) over the radial arteries and dorsalis pedis and posterior tibial arteries. Reduced oscillometry is more associated with abnormalities than the other tests, and more than STD. The work of Mulvany and his colleagues suggests an explanation for the low oscillometry. Larger vessels than the arterioles and digital vessels can become resistance vessels in various circumstances. It is likely that the radial artery and vessels of similar diameter can temporarily act as resistance vessels in patients with acrocyanosis in a low temperature environment.

Adolescent↗
PubMed1992

Epinephrine and norepinephrine release from bullfrog gastrointestinal sympathetic postganglionic endings at a high ambient temperature.

The influence of a high ambient temperature on sympathetic neurotransmitter release in bullfrogs was studied. Gastrointestinal vascular perfusates were collected before and after splanchnic nerve stimulation, and their content of epinephrine and norepinephrine was determined. A marked increase in epinephrine and norepinephrine release was observed following stimulation at 29-32 degrees C, indicating that epinephrine and norepinephrine may both act as adrenergic transmitters in a high-temperature environment.

Animals↗
PubMed1976

Thermal adaptation in yeast: growth temperatures, membrane lipid, and cytochrome composition of psychrophilic, mesophilic, and thermophilic yeasts.

The temperature limits of growth of a number of yeast species were examined, and on this basis the organisms were classified into different thermal categories. The following species were examined: Leucosporidium frigidum and Leucosporidium nivalis, psychrophilic, temperature limits of growth, -2 to 20 degrees C; Canadian lipolytica mesophilic, temperature limits of growth, 5 to 35 degrees Candida parapsilosis and Saccharomyces telluris, thermotolerant, temperature limits of growth, 8 to 42 degrees C; Torulopsis bovina and Candida slooffi, thermophilic, temperature limits of growth, 25 to 45 degrees C and 28 to 45 degrees C, respectively. The membrane lipid and cytochrome composition of mitochrondrial fractions isolated from these yeasts were compared. There was a direct correlation between the growth temperature and the degree of membrane of lipid unsaturation; the lower the temperature, the greater the degree of lipid unsaturation. The membrane lipid composition of the thermophilic yeasts were distinguished by the high percentage (30 to 40%) of saturated fatty acid, as compared with the mesophilic and psychrophilic yeasts. The latter contained approximately 90% unsaturated fatty acid, 55% of which was linolenic acid, C alpha-18:3. Changes in phospholipid composition in relation to temperature were also noted. The respiratory-deficient thermophile, C. slooffi, was characterized by the absence of cardiolipin (sensitivity 0.1 mug of phosphorus) and cytochrome aa3. The absence of conventional mitochondrial structures in this thermophilic microorganism is tentatively suggested although low concentrations of cytochromes b, c, and c1 were detected by low-temperature spectroscopy. On the other hand, the respiratory-competent thermophile, T. bovina, was characterized by a high cardiolipin (25% of the total phospholipid) and cytochrome aa3 content (1 nmol/mg of mitochrondrial protein). Low-temperature spectra showed the presence of one b-type cytochrome in the thermophilic yeasts, two b-type cytochromes in the mesophilic yeasts, and three b-type cytochromes in the psychrophilic yeasts. It was concluded that a knowledge of the properties of the biological membrane is fundamental to an understanding of the ability of a microorganism to grow and reproduce in different temperature environments.

Adaptation, Physiological↗
PubMed1975

Ascorbic acid changes in cultured rabbit lenses after microwave irradiation.

Whole body exposure of rabbits to microwave radiation causes a decrease in ascorbic acid in the lens. In our study, rabbit lenses maintained in culture medium (37 degrees C) were exposed to either pulsed or continuous wave S-band radiation for 10-15 min at power densities between 0 and 200 mW/cm-2. Total ascorbic acid was measured in selected lenses 1-3 days after irradiation. The temperature of the culture medium was measured during irradiation. Matched control lenses were exposed to similar time-temperature environments, but without microwave irradiation. Ascorbic acid decreased significantly in lenses exposed to microwave radiation. No differences were found, however, between irradiated and control lenses subjected to identical time-temperature conditions. At a given average power density, the time-temperature variation was independent of modulation. A decrease in ascorbic acid is apparently a direct thermal effect of microwave radiation in rabbit lens culture.

Animals↗
PubMed1976

The influence of short term exposure to two different environmental temperatures on electrolyte concentrations of fowl semen.

The concentration of some of the electrolytes found in fowl semen changed when birds were transferred from a temperature environment of 19 degrees C to either 8 degrees or 30 degrees C. The pH of the semen obtained from males transferred to the 30 degrees C. environment significantly decreased as opposed to a significant increase in the pH of the semen obtained from males transferred to the 8 degrees C. environment. Sodium and potassium concentrations significantly increased in whole semen in both transfer groups, while magnesium increased significantly only in whole semen from males transferred to the 8 degrees C. environment. Sodium increased in seminal plasma when the males transferred from 19 degrees C. environment to the 8 degrees C. environment. The data indicate that an abrupt change to either a warmer or colder environment causes a change in electrolyte concentration of cock semen.

Animals↗
PubMed1977

Work-heat tolerance of distance runners.

Physical training in a cool environment by subjects not previously trained improves their work-heat tolerance, but can not replace heat acclimatization to the standard heat stress conditions employed by a variety of investigators. This is attributed to the inability of these subjects to sustain prolonged work at high metabolic rates. Thus, they are not maintaining high core body temperatures long enough to bring about an adaptive change to heat. On the other hand, the intense and prolonged (years) training of long distance runners in a temperature environment at high metabolic rates has acclimatized them for at least 4 hours of mild work (MR 160 kcal/m2-hr) in both hot dry (50/27 C db/wb) and hot wet (36.7/33.1 C db/wb) environments, but not for work at high energy expenditures (MR 540 kcal/m2-hr) in a less severe thermal stress (35/21 C db/wb). These highly trained athletes can improve their work-heat tolerance at high metabolic rates in a warm climate by training at competitive speeds in a cool environment dressed in sweat clothing or by training at near competitive speeds in the heat. In either of these situations the athlete is cautioned to consume water at frequent intervals to offset the dehydration associated with excessive sweating under these conditions.

Acclimatization↗