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At least 19 recordsLinked to original sources

PubMed1977

Effect of temperature and temperature shifts on growth and branching of a wild type and a temperature sensitive colonial mutant (Cot 1) of Neurospora crassa.

Growth of a temperature sensitive colonial mutant (cot 1) of Neurospora crassa was compared with a wild type strain. The hyphal growth unit (the ratio between mycelial length and number of branches) of the wild type was not appreciably altered by temperature and there was a direct relationship between the specific growth rate (alpha) of these mycelia and their mean hyphal extension rate (E). The specific growth rate of cot 1 increased by about the same relative amount as the wild type between 15 degrees and 30 degrees C. Cot 1 grew and branched normally at 15 degrees and 25 degrees C but at 30 degrees C the hyphal growth unit and mean hyphal extension rate of the mutant mycelia were reduced. Thus, between 15-30 degrees C the ratio, E/alpha was constant for the wild type but not for cot 1. The effect of temperature and temperature shifts on extension zone length (2), extension zone expansion time (2t) and branching of leading hyphae of mature colonies were also studied. It is suggested that branching is governed by a mechanism which regulates the linear growth rate of hyphae; the cot 1 mutation may have a direct effect on wall extension or affect linear growth rate indirectly due to an influence on the transport of precursors to the tip.

Mutation↗

PubMed1979

Comparative studies of wild-type and cold-mutant (temperature-sensitive) influenza viruses: independent segregation of temperature-sensitivity of virus replication from temperature-sensitivity of virion transcriptase activity during recombination of mutant A/Ann Arbor/6/60 with wild-type H3N2 strains.

RNA 1 (see end of Summary) of a cold-adapted and temperature-sensitive (ts) influenza virus mutant A/Ann Arbor/6/60 has a different mobility from RNA 1 of wild-type (wt) A/Ann Arbor/6/60 when subjected to electrophoresis through acrylamide/agarose gels in the absence of denaturing agents. Detection of this lesion in RNA 1 of the mutant virus was dependent on the temperature of the gel during electrophoresis. Because RNA 1 is believed to code for a protein involved in virus-specific RNA synthesis we compared phenotypes of virion transcriptases in the wt and mutant viruses. The enzyme of the mutant virus was found to be about 40% less active at 40 degrees C than the enzyme of the wt virus when related to their activities at 31 degrees C. Two cold-adapted ts recombinants which derive their RNA 1 from the mutant A/Ann Arbor/6/60 have virion transcriptases with a phenotype similar to that of their mutant parent. Three different cold-adapted ts recombinants, however, which also derive their RNA 1 from the mutant A/Ann Arbor/6/60, have virion transcriptases with a phenotype similar to that of wt virus. We conclude, therefore, that the conditional-lethal ts property of A/Ann Arbor/6/60 mutant and its recombinants is independent of the phenotypic marker observed for the A/Ann Arbor/6/60 mutant virion transcriptase, and that the lesion in RNA 1 of the mutant may also be unrelated to the observed difference between virion transcriptases of the mutant and wt A/Ann Arbor/6/60 viruses. The phenotypes of the virion transcriptases in recombinants did, however, correlate with the derivation of their RNA 2. This suggests that the increased temperature-sensitivity of virion transcriptase of the A/Ann Arbor/6/60 mutant is caused by either (1) a lesion (not necessarily conditionally lethal) that occurred in its RNA 2 during the course of cold-adaptation, or (2) a lesion in another gene whose product is a component of the virion transcriptase complex, but which lesion is only expressed phenotypically when there is a synergistic interaction in the transcriptase complex with the product of A/Ann Arbor/6/60 rna 2.

Cold Temperature↗

PubMed1979

Survival in subzero temperatures: two field experiments on temperature estimation and "snowhole" (survival hole) temperatures.

Two field experiments in a subarctic environment are described. Individuals consistently underestimated the degree of cold, because visual cues dominated sensory skin receptors in the subjective estimation of temperature. In snowholes (survival holes) temperatures rose 20 degrees C within 30 minutes of occupancy, but stabilized at freezing point. Implications for travel and survival in a subzero environment are described.

Cold Climate↗

PubMed1977

Interaction of air temperature and core temperatures in thermoregulation of the goat.

1. The interaction between air temperature, hypothalamus temperature, and spinal cord temperature in driving heat production and respiratory evaporative heat loss has been studied in conscious goats with chronically implanted thermodes. 2. Thermoregulatory heat production could be described as being approximately proportional to the sum of two linear drives determined by hypothalamus temperature and spinal cord temperature. This was found also for respiratory evaporative heat loss except that it was not influenced by spinal cord cooling. 3. Thermoregulatory heat production could be further described as being approximately proportional to a product of linear drives determined by hypothalamus and spinal cord temperature on one hand and air temperature on the other. Respiratory evaporative heat loss was approximately proportional to the sum of drives determined by spinal cord, hypothalamus and air temperatures. 4. Sensitivity to central cooling was found to undergo long-lasting but temporary changes which interfered with the immediate effects of air temperature on thermoregulation. 5. Central threshold temperatures for heat production and respiratory evaporative heat loss were found to be differently affected by air temperature. This indicates that integrating mechanisms for heat production and respiratory evaporative heat loss are to some extent functionally independent.

Animals↗

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↗

PubMed1976

The relationship of skin temperatures of clothed adults to ambient temperature in a warm environment.

In forty-one apyrexial adult male patients, who were clothed in light-weight cotton pyjamas, mean skin temperature was determined and, simultaneously, ambient temperature and the temperature of air space under clothing were measured. Both mean skin temperature and the temperature of the air space under clothing showed a linear increase with ambient temperature. Heat loss by vapourization of water is known to have a curvilinear relationship to ambient temperature. Application of the temperature relationships obtained in this study to the vapourization curve indicates that clothing shifts the point of sharp upward inflection of the curve to the left; and, if ambient temperature is to be employed to predict the amount of cutaneous water loss in clothed individuals, the extent of this shift must be determined. The data obtained in the present study has been applied to studies of evaporative water loss in Lagos.

Adult↗

PubMed1977

Effect of environmental temperature stress on intramammary infections of dairy cows and monitoring of body and intramammary temperatures by radiotelemetry.

Four dairy cows were stressed by exposure to hot and cold environments in tests to determine the effect of environment on milk yield, somatic cell counts, and California mastitis test scores of milk from all mammary quarters and on bacterial counts of milk from infected quarters. Two cows were held in temperature-controlled rooms for successive 5-day periods at moderate (21 to 28 C), cold (-16 C), moderate, hot (36 to 37 C), and moderate environments. The cold and hot sequences were reversed for the other 2 cows. Temperature transmitters were surgically implanted in the skeletal muscles of the loin and gluteal regions; however, only one of these transmitters (gluteal region) functioned continuously throughout the experiment. At the end of this experiment, a transmitter was implanted in the gland cistern of a rear quarter of 1 cow, and the sequence of holding in the cold before the hot environment was used. Mean body temperature was approximately 1 degree higher (39.2 C) in the hot room (1 cow) and 3 to 4 degrees lower (35 C and 33 C), respectively, for 2 cows) in the cold room than that during the moderate temperature periods. A similar comparison showed that the mean intramammary temperature was 1 to 2 degrees higher (39.5 C) in the hot room and approximately 9 degrees lower (29.4 C) in the cold room. Exposure of the cows to hot and cold environments caused a greater loss in milk production in the 2 medium-yielding cows (23 to 28 kg/day) than in the 2 low-yielding cows (9 to 13 kg/day). The effect of the extreme temperatures on the somatic cell counts in uninfected quarters was limited to only a few quarters and was inconsistent (mean counts increased and decreased at both temperatures). The California mastitis test reactions showed no consistent changes during periods of heat and cold stress. Also, the effect of the environmental temperature on the intramammary infections also was inconsistent. The effect on bacterial counts appeared to vary with the type of organism. Some mean counts decreased in the heat and cold (Streptococcus agalactiae, Micrococcus sp), some increased (Pseudomonas sp), and another seemed independent (Streptococcus uberis) of the environmental temperature at which the cow was held.

Animals↗

PubMed1977

Physiological effects of growth of an Escherichia coli temperature-sensitive dnaZ mutant at nonpermissive temperatures.

The physiological effects of incubation at nonpermissive temperatures of Escherichia coli mutants that carry a temperature-sensitive dnaZ allele [dnaZ(Ts)2016] were examined. The temperature at which the dnaZ(Ts) protein becomes inactivated in vivo was investigated by measurements of deoxyribonucleic acid (DNA) synthesis at temperatures intermediate between permissive and nonpermissive. DNA synthesis inhibition was reversible by reducing the temperature of cultures from 42 to 30 degrees C; DNA synthesis resumed immediately after temperature reduction and occurred even in the presence of chloramphenicol. Inasmuch as DNA synthesis could be resumed in the absence of protein synthesis, we concluded that the protein product of the dnaZ allele (Ts)2016 is renaturable. Cell division, also inhibited by 42 degrees C incubation, resumed after temperature reduction, but the length of time required for resumption depended on the duration of the period at 42 degrees C. Replicative synthesis of cellular DNA, examined in vitro in toluene-permeabilized cells, was temperature sensitive. Excision repair of ultraviolet light-induced DNA lesions was partially inhibited in dnaZ(Ts) cells at 42 degrees C. The dnaZ(+) product participated in the synthesis of both Okazaki piece (8-12S) and high-molecular-weight DNA. During incubation of dnaZ(Ts)(lambda) lysogens at 42 degrees C, prophage induction occurred, and progeny phage were produced during subsequent incubation at 30 degrees C. The temperature sensitivity of both DNA synthesis and cell division in the dnaZ(Ts)2016 mutant was suppressed by high concentrations of sucrose, lactose, or NaCl. Incubation at 42 degrees C was neither mutagenic nor antimutagenic for the dnaZ(Ts) mutant.

Alleles↗

PubMed1976

Effects of altering spinal cord temperature on temperature regulation in the Adelie Penguin, Pygoscelis Adeliae.

In 6 Adelie penguins, thermodes were implanted in the cervical and upper thoracic spinal canal. At thermoneutral (+8 to +16 degrees C) and cold (-18 to -22 degrees C) ambient conditions, the effects of spinal canal heating and cooling on the surface temperature of one flipper (skin blood flow), oxygen consumption (metabolic heat production) and esophageal (core) temperature were observed in the conscious animals.- At thermoneutral ambient conditions, spinal cord cooling reduced and spinal heating increased skin blood flow. Only very strong spinal cooling induced small increases of oxygen consumption, while spinal heating had no effect at all. The relation between spinal canal temperature and metabolic heat production at thermoneutral ambient conditions could be described by a linear regression with a slope of -0.05 W. KG-1 . DEGREES C-1. -At cold ambient conditions, the skin vessels of the flippers were permanently constricted and an increase of metabolic heat production by 5-50% of the resting rate developed within 1-3 h of cold exposure. Spinal cord cooling augmented metabolic heat production. Spinal heating reduced heat production but did not release skin vasoconstriction even at high stimulus intensities. The relation between spinal canal temperature and metabolic heat production in the cold could be described by a linear regression with a slope of -0,52 W. kg-1 . degrees C-1. -It is concluded that temperature sensors with specific functions in temperature regulation are located in the spinal cord of the Adelie penguin. These sensors contribute to the central temperature signal input in the hypothermic and hyperthermic ranges of core temperature. The peripheral thermal conditions strongly influence the responsiveness of the various thermoregulatory effectors to the spinal thermal stimulus.

Animals↗

PubMed1976

Effects of altering rostral brain stem temperature on temperature regulation in the Adelie penguin, Pygoscelis adeliae.

In 4 Adelie penguins, thermodes were implanted in the rostral brain stem. Two animals were additionally equipped with spinal canal thermodes. At thermoneutral (+8 to +16 degrees C) and cold (-18 to -22 degrees C) ambient conditions, the effects of hypothalamic heating and cooling on the surface temperature of one flipper (skin blood flow), oxygen consumption (metabolic heat production) and esophageal (core) temperature were observed in the conscious animals.- Heating the rostral brain stem induced heat defence responses: Heat production was reduced in the cold and skin vasodilatation was evoked at thermoneutral ambient conditions. As a rule, core temperature fell during rostral brain stem heating.- Cooling the rostral brain stem did not induce clear-cut cold defence responses. On the contrary, strong cooling at thermo-neutral ambient conditions induced vasodilation in the skin. In the cold, even slight degrees of rostral brain stem cooling decreased metabolic heat production. As a rule, core temperature fell when the rostral brain stem was cooled.- It is concluded from the results that thermosensitive structures in the stimulated section of the rostral brain stem of the Adelie penguin contribute to the central temperature signal input in the range of normal to elevated core temperatures. These hypothalamic warm signals appear to be at least as effective as spinal warm signals in controlling skin blood flow and metabolic heat production. The inhibition of ongoing thermoregulatory effector activity by rostral brain stem cooling suggests positive temperature coefficients of the integrative and/or efferent neurons in the hypothalamic temperature regulation center of the Adelie penguin.

Animals↗

PubMed2026

Maternal and developmental temperature modulate adult response to temperature in Drosophila melanogaster.

Beyond inherited genes and environmentally induced changes in gene expression, phenotypes can also be shaped by parental effects-an effect from a parental phenotype that causes modifications in offspring traits, which cannot be solely explained by the parental or offspring genomes. Such effects may prepare offspring for future environmental conditions and contribute to phenotypic plasticity, including responses to temperature. While temperature-induced plasticity has been extensively studied, the relative contributions of parental versus direct environmental cues remain poorly understood. The fruit fly Drosophila melanogaster is a powerful model for studying physiological and behavioral adaptation to temperature. Flies inhabit environments spanning broad thermal ranges and show evidence of parental effects, such as increased heat tolerance in offspring from warm-reared parents. Here, we exposed mothers to two experimental temperatures and split their broods between the same two temperatures to estimate the relative importance of maternal and developmental effects on adult physiological and developmental responses to temperature. We find that the reaction norms of locomotor activity under gradually increasing temperatures, responses to heat-shock and cold-shock, and fecundity are mostly governed by direct plastic responses to developmental environment. We detected comparatively weak maternal effects in the response to heat-shock, fecundity, and grand-offspring survival where matched environments counteracted the effects of direct offspring experience. We conclude that thermal experience during development is the primary determinant of phenotypic plasticity in D. melanogaster, while maternal experience contributes a small but non-negligible component.

Animals↗

PubMed1978

Telemetry measured body temperature of domestic fowl at various ambient temperatures.

Adult, male Single Comb White Leghorn chickens (SCWL) were housed unrestrained in individual cages in a controlled environment room with a photoperiod of 12L:12D. By means of surgically implanted radio transmitter, body temperatures were recorded hourly for five consecutive days at each of six experimental temperatures: 23, 26, 29, 32, 35, and 38 C. The data were evaluated statistically by correlogram, periodogram, and harmonic analysis. Period length of each cycle was about 24 hr at all ambient temperatures. No significant differences in deep body temperature were observed until the ambient temperature reached 32 C; but highly significant increases were detected between 32, 35, and 38 C. Diurnal differences in body temperature ranged from .6 to 1.1 C. It has been suggested that the body temperature of male chicken may be under the control of a biological clock that synchronizes with the solar day.

Animals↗

PubMed1978

Preliminary characterization of a temperature-sensitive mutant of Moloney murine leukemia virus that produces particles at the restrictive temperature.

The isolation and preliminary characterization of a new temperature-sensitive mutant of Moloney murine leukemia virus, designated ts7, are reported. The infectivity of ts7, determined by a focus-forming unit assay, was reduced at least 100-fold when the virus was assayed at the nonpermissive temperature (39 degrees C) as compared with assay at the permissive temperature (34 degrees C). However, several lines of evidence indicated that the diminution of ts7 titer at 39 degrees C is not due to its inability to form virus particles at that temperature. The supernatant from ts7-infected cells grown at 39 degrees C showed significant infectivity when assayed at 34 degrees C; only small reductions in reverse transcriptase activity and fusion ability were observed when compared with supernatant from 34 degrees C ts7-infected cultures. That particles are produced at the nonpermissive temperature was confirmed by transmission electron microscopy of the supernatant from ts7-infected cells at 39 degrees C and by transmission electron microscope observations of mature particles trapped in the intercellular spaces of pelleted thin cell section. A possible explanation for the productivity at 39 degrees C of particles that are infectious at 34 degrees C but not at 39 degrees C is that the virus is heat labile at the nonpermissive temperature. Consistent with this hypothesis is the extreme heat lability of virus harvested at 34 degrees C. Such virus, when incubated at 39 degrees C, has a half-life one-sixth that of identical virus incubated at 34 degrees C, or that of wild-type virus at either temperature.

Cell Fusion↗

PubMed1976

Temperature and endocrine activity during sleep in man. Activation of cortisol and thyroid-stimulating hormone, inhibition of human growth hormone secretion by raised or decreased ambient and body temperatures.

1. Polygraphic night sleep recordings in eight healthy male volunteers with simultaneous measurement of rectal temperature, plasma growth hormone (HGH), cortisol, and TSH concentrations were performed during normal, raised, and lowered ambient and body temperature. 2. There was a statistically significant increase in plasma cortisol and TSH levels during cold nights with a smaller rise during high temperatures. 3. Growth hormone levels, measured as the mean highest plasma concentration in the first two NREM-REM sleep cycles, were slightly lower during hot and cold nights than corresponding baseline values. It is suggested that there may be an inverse relation between ACTH and HGH secretion by the anterior pituitary gland. 4. During the nights of high ambient temperature, decreased total duration of sleep and particularly low values of paradoxical sleep were observed. Night sleep in low ambient temperature with a significant decrease of body temperature is not different from baseline conditions. 5. The results suggest that a pronounced increase in stress hormone secretion may occur without changes in polygraphic EEG criteria.

Adult↗

PubMed1978

The temperature sensitive mutant 72c. II. Accumulation at high temperature of ppGpp and pppGpp in the presence of protein synthesis.

A heat sensitive mutant of E. coli has been analyzed. A shift to restrictive temperature leads to an accumulation of ppGpp and pppGpp in both the parental and the mutant strains (both are relA+). The pool of these compounds is shown to decrease with time after the temperature shift in the case of the parental strain, but remains at the same elevated level in the case of the mutant. The temperature shift of the mutant leads to an apparent reduction of stable RNA synthesis; this inhibition can be released by chloroamphenicol or tetracycline. Gross protein synthesis is more or less unaffected at restrictive temperature. In the parental strain little effect is seen on RNA and protein synthesis after the temperature shift. A relA derivative of the mutant does not show the same inhibition of RNA synthesis at high temperature. Sedimentation analysis suggests that mutant 70S ribosome are more stable, when exposed to a lowered Mg2+ concentration, than are 70S ribosomes from the parental strain. In addition, the relative amounts of the two forms of ribosomal protein S6, which can be obtained on DEAE chromatography (Held et al., 1973), are significantly changed in the mutant.

Bacterial Proteins↗

PubMed1977

Analogs of endoperoxide precursors of prostaglandins: failure to affect body temperature when injected into primary and secondary central temperature controls.

It is known that central administration of prostaglandins of the E series has marked effects on body temperature. The purpose in the present experiments was to learn whether stable analogs of the cyclic endoperoxide precursors of PGE2, PGF2alpha and PGD2, injected into the primary temperature control in the preoptic/anterior (PO/AH) hypothalamic region and into a presumed secondary control in the medulla oblongata, can produce rises in body temperature similar to those caused by PGE2. Injection of the analogs U-44069 and U-46619 (1.0 and 2.0 microng) into the PO/AH region of the rat, where both PGE2 and PGE1 caused hyperthermia, had no effect on Tre. Likewise, injections into the medulla oblongata, in the region where PGE2 and PGE1 caused hypothermia, were ineffective in altering body temperature. That neurons important to the control of body temperature are selectively sensitive to PGE2 and not to analogs of prostaglandin precursors suggests that local cyclic endoperoxides can influence body temperature only through bioconversion to prostaglandin.

Animals↗

PubMed1978

Temperature stress and immunity in mice: effects of environmental temperature on the antibody response to human immunoglobulin of mice, differing in age and strain.

Physiological responses at different ambient temperatures and temperature-dependent changes in immune responsiveness are polymorphic. At 4 degrees C, the antigen elimination from the bodies of SJL and C57Bl/6 mice is accelerated. In SJL, but not in C57Bl/mice, the half-life of antigen elimination decreased between the ages of 3 and 11 weeks. Parental mice and their F1 hybrids showed a fall in rectal temperature, which was greatest in young animals. Hypothermia was greater in C57Bl/6 than in SJL and F1 hybrids; in 3 week old C57Bl/6 it resulted in high mortality. The response to aggregated human immunoglobulin (HGG) was evaluated by (a) the number of animals with detectable antibody, (b) the minimal dose of antigen eliciting detectable antibody, and (c) the mean titre of haemagglutinating antibody. SJL mice were more responsive than C57Bl/6 mice. Low antibody formation in the secondary response was dominant, i.e. the amount of antibody produced by (SJL X C57Bl/6)F1 mice was the same as that produced by the parental C57Bl/6 strain. In a primary response, the quantity of antibody varied with the age of the immunized animal; 18 week old mice responded to lower minimal doses of antigen and produced more haemagglutinating antibody than 3 week old animals. After a second injection with HGG, SJL but not C57Bl/6 mice produced more antibody when kept at 14 degrees C rather than at 22 degrees C or 30 degrees C, and produced the lowest antibody titres when kept at 4 degrees C. The relation between ambient temperature and the response of the SJL mice was dominant over that of the C57Bl/6strain. Primary differed from secondary responsiveness in that neither strain produced significantly lower titres when ambient temperature fell to 4 degrees C; only 18 week old SJL mice responded with a marginal decrease in peak antibody production. The described polymorphism may affect both the individual capacity to cope with low temperatures and the evolutionary adaptation of a species to climatic extremes.

Age Factors↗

PubMed1979

Effect of blocking protein synthesis at nonpermissive temperatures on temperature-sensitive deoxyribonucleic acid mutants of Escherichia coli.

When protein synthesis was blocked in temperature-sensitive deoxyribonucleic acid synthesis mutants of Escherichia coli at nonpermissive temperatures, it reduced the amount of apparent subsequent chain elongation to approximately half that observed in the mutants either at nonpermissive temperatures alone or when protein synthesis was blocked at the permissive temperature. Blocking protein synthesis at the nonpermissive temperatures for periods of 40 min caused the loss of ability to reinitiate deoxyribonucleic acid synthesis at the permissive temperature.

Amino Acids↗