The cDNA encoding Xenopus laevis heat-shock factor 1 (XHSF1): nucleotide and deduced amino-acid sequences, and properties of the encoded protein

We have isolated a cDNA encoding Xenopus laevis (Xl) heat-shock factor 1 (XHSF1). XHSF1, translated from the mRNA synthesized in vitro, will bind specifically to the X1 hsp70 promoter (hsp70). Microinjection of XHSF1 mRNA into Xl oocytes leads to synthesis of XHSF1 which accumulates in the nucleus and selectively activates Xl phsp70p activity at 18°C.     

Immunological detection of cloned antigenic genes of Vibrio cholerae in Escherichia coli

Antibodies have been used as probe to detect cloned genes coding for toxin and surface antigens of Vibrio cholerae E1 Tor strain KB207. Eco RI-digested chromosomal DNA of KB207 was cloned in plasmid pBR325 and transformed in Escherichia coli HB 101(λcI857). Transformants were grown at 32° C on plates containing antibodies. Lysogen was induced at 42 °C to release expressed antigens. Antigen-antibody reaction produced a halo around positive clones.     

Critical thermal maximum and body water loss in first instar larvae of three Cetoniidae species (Coleoptera)

Critical thermal maximum (CT_max) and body water losses were measured in first instar larvae of Gnorimus nobilis, Osmoderma eremita (Trichiinae) and Cetonischema aeruginosa (Cetoniinae) when air temperature was increased gradually (0.5 °C/min) from 20 °C to the critical thermal maximum (CT_max), in dry air (near 0% R.H.).

The CT_max was significantly lower in O. eremita (45.6±0.7 °C) than in G. nobilis (48.5±0.6) and C. aeruginosa (51.4±0.9 °C).

An increase of 10 °C (30–40 °C) induced a 2-fold increase of the water loss in C. aeruginosa and O. eremita (Q₁₀=2.10±0.12 and 2.13±0.20, respectively). In the range from 40 to 45 °C to CT_max a strong increase of the water loss was observed in O. eremita and C. aeruginosa, respectively. Body water losses were significantly lower in C. aeruginosa than in O. eremita and G. nobilis over the range 20 °C—CT_max; no significant difference occurred between G. nobilis and O. eremita.     

Thermal avoidance and preference in Daphnia magna

1. Water fleas (Daphnia magna) bred at 23°C were non-responsive to temperatures between 13 and 25°C.

2. At the lower (11°C) and upper limits (30°C) their klinokinetic avoidance behaviour showed a larger intraindividual than interindividual variation.

3. Thermal sensitivity for avoidance responses in D. magna was about 1.5°C.

4. For D. magna bred for one parthenogenetic generation at 14°C heat avoidance temperature was about 8°C lower, and cold avoidance temperature was about 1°C higher than in D. magna from 23°C.

5. In group experiments the animals showed some preference for the acclimation temperature.

6. Cold induced stenothermy and warm induced eurythermy in D. magna were related to the mode of reproduction.

hsp23 and hsp26 exhibit distinct spatial and temporal patterns of constitutive expression in Drosophila adults

To determine differences in the patterns of expression of Drosophila small heat shock proteins (shsp) during normal development in the absence of stress, proteins obtained from head, thorax and gonads of young (0–12 h, 3 days), middle-aged (3–6 days) and 15- to 20-day-old adult flies were separated on SDS-PAGE gels and blotted with monoclonal antibodies against hsp23 and hsp26. hsp23 was found in the heads and gonads of young males and females. In contrast, the maximum expression of hsp26 was seen in gonads of young flies, and it was only lightly detected in the brain. The expression of both proteins decreased as flies aged. This age-related decrease was particularly striking for hsp23 in females. The immunoblot results obtained were complemented by immunostaining of thin parasagittal sections of whole fly bodies Hsp23 was found to be expressed in the brain, thoracic ganglion, fat body and gonads of young (0-12 h) males and females. On the other hand, hsp26 was essentially detected in ovaries and testes of these young flies. The analysis of the tissue expression of both proteins demonstrate that each shsp has a distinct cellular localization. In the central nervous system, hsp23 and hsp26 were present in the neurocytes of the brain and the thoracic ganglion. In addition, hsp23 (but not hsp26) was also detected in the central neuropile of these two organs. In testis, hsp26 was localized in the cytoplasm of spermatocytes and, probably, in the spermatid bundles. In contrast, hsp23 was detected at the periphery of cells (membranes). In ovorioles of newborn females the expression of hsp26 was stronger, and the maximum expression of hsp23 was only reached in older (2 days and more) flies. These results demonstrate that each shsp possesses a specific spatial and temporal pattern of expression in adults of Drosophila. The distinct tissue-specific and age-dependent expression of hsp23 and hsp26 suggests that these two proteins may have different functions in crucial organs of Drosophila. © 1993Wiley-Liss, Inc.     

Effect of nifedipine on core cooling in rats during tail cold water immersion

Male rats (450 g, n=11/group) were heated at an ambient temperature of 42°C until a rectal temperature of 42.8°C was attained. Rats, then received either saline (30°C)+tail ice water immersion (F+I) or saline (30°C)+tail ice water immersion+Nifedipine, a peripheral vasodilator, (F+I+N) to determine cooling rate effectiveness and survivability. The time to reach a rectal temperature of 42.8°C averaged 172 min in both groups resulting in similar heating rates (0.029°C/min). The cooling rates in group F+I and F+I+N were not significantly different from each other. We conclude that since Nifedipine did not improve cooling rates when combined with fluid+tail ice water immersion, its use as a cooling adjunct does not seem warranted.     

Temperature-mediated characteristics of the dusky salamander (Desmognathus fuscus) of southern Appalachia

Thermal preference of the salamander Desmognathus fuscus was measured in a linear thermal gradient with floor temperatures ranging from 10 to 30°C. Salamanders were acclimated to 21±1°C and a 12 : 12 photoperiod with photophase centered at 1200 h for 8 weeks prior to being placed in the gradient. Substrate temperatures were measured under the salamanders’ stomachs from 1200 to 2400 h at 2 h intervals immediately after feeding and after seven days fasting. We found no selection for temperature in fasting or postprandial D. fuscus. We compared the rate at which D. fuscus cooled and heated with that of a control and found no significant difference. We determined the desiccation rate of D. fuscus at 16 and 26°C and found a significantly more rapid desiccation at 26°C.     

Determination of the maximum and minimum lethal temperatures (LT50) for Loxosceles intermedia Mello-Leitão, 1934 and L. laeta (Nicolet, 1849) (Araneae, Sicariidae)

In this study, the maximum and minimum lethal temperatures (LT₅₀) of L. intermedia and L. laeta were determined in two treatments: gradual heating (25–50°C) and cooling (25°C to −5°C), and 1 h at a constant temperature. In gradual temperatures change, L. intermedia mortality started at 40°C and the LT₅₀ was 42°C; for L. laeta, mortality began at 35°C and the LT₅₀ was 40°C. At low temperatures, mortality was registered only at −5°C for both species. In the constant temperature L. intermedia showed a maximum LT₅₀ at 35°C and L. laeta at 32°C; the minimum LT for both species was −7°C.     

Efficient insertional mutagenesis in group A streptococci mediated by Tn917 transposon

The replication-conditional thermosensitive vector pTV1-OK (repATs, Kan^r) harbouring the transposon Tn917 (Em^r) was successfully used to mutagenise a clinical Streptococcus pyogenes isolate (CS101). In the initial studies, conditions were established for electrotransformation of the pTV1-OK vector into CS101. Transformants selected on media containing Kan at 29°C were shown to become Kan^s at 39°C and to carry the transposon-linked Em^r marker. One such transformant was chosen for transposition studies. Upon temperature shift, transposition was achieved with a frequency of approximately 0.01% with a plasmid curing efficiency of close to 100%. Southern blot analysis demonstrated that the majority of mutants contained a single copy of Tn917 and showed no evidence for preferential sites of integration (“hot spots”). Screening of Tn917 libraries of S. pyogenes has led to the identification of mutants lacking either haemolysing or plasminogen activating activity. Mutants defective in each of these activities were identified at a frequency of approximately one in 1000 to 4000 colonies. These findings suggest that the pTV1-OK vector can be used for transposon mutagenesis of S. pyogenes and that this strategy will be valuable for identifying virulence factors and regulatory mechanisms in these bacteria.     

Human hsp27, Drosophila hsp27 and human alphaB-crystallin expression-mediated increase in glutathione is essential for the protective activity of these proteins against TNFalpha-induced cell death.

Expression of small stress proteins (shsp) enhances the survival of mammalian cells exposed to heat or oxidative injuries. Recently, we have shown that the expression of shsp from different species, such as human hsp27, Drosophila hsp27 or human alphaB-crystallin protected murine L929 cells against cell death induced by tumor necrosis factor (TNFalpha), hydrogen peroxide or menadione. Here, we report that, in growing L929 cell lines, the presence of these shsp decreased the intracellular level of reactive oxygen species (ROS). shsp expression also abolished the burst of intracellular ROS induced by TNFalpha. Several downstream effects resulting from the TNFalpha-mediated ROS increment, such as NF-kappaB activation, lipid peroxidation and protein oxidation, were inhibited by shsp expression. We also report that the expression of these different shsp raised the total glutathione level in both L929 cell lines and transiently transfected NIH 3T3-ras cells. This phenomenon was essential for the shsp-mediated decrease in ROS and resistance against TNFalpha. Our results therefore suggest that the protective activity shared by human hsp27, Drosophila hsp27 and human alphaB-crystallin against TNFalpha-mediated cell death and probably other types of oxidative stress results from their conserved ability to raise the intracellular concentration of glutathione.     

Metabolism and thermoregulation in Maximowiczi's voles (Microtus maximowiczii) and Djungarian hamsters (Phodopus campbelli)

1 Metabolic rates (Vo₂), body temperature (T_b), and thermal conductance (C) were first determined in newly captured Maximowiczi's voles (Microtus maximowiczii) and Djungarian hamsters (Phodopus campbelli) from the Inner Mongolian grasslands at a temperature range from 5 to 35 °C.

2 The thermal neutral zone (TNZ) was between 25 and 32.5 °C for Maximowiczi's voles and between 25 and 30 °C for Djungarian hamsters. Mean T_b was 37.0±0.1 °C for voles and 36.2±0.1 °C for hamsters. Minimum thermal conductance was 0.172±0.004 ml O₂/g h °C for voles and 0.148±0.003 ml O₂/g h °C for hamsters.

3 The mean resting metabolic rate within TNZ was 2.21±0.05 ml O₂/g h in voles and 2.01±0.07 ml O₂/g h in hamsters. Nonshivering thermogenesis was 5.36±0.30 ml O₂/g h for voles and 6.30±0.18 ml O₂/g h for hamsters.

4 All these thermal physiological properties are adaptive for each species and are shaped by both macroenvironmental and microenvironmental conditions, food habits, phylogeny and other factors.

Temperature acclimation of axonal functions in the crayfish Astacus astacus L.

1. 1.|Crayfish (Astacus astacus L.) were acclimated for 1–3 weeks at 5 and 20°C. The effects of temperature on the functions of the unicellular medial giant axon were studied.

2. 2.|The resting membrane potential of the giant axon increased slightly with the experimental temperature from 2 to 32°C. The temperature dependence of the resting membrane potential could be described by two lines, which intersected at about 12°C in cold-acclimated crayfish and at about 16°C in the warm-acclimated.

3. 3.|The amplitude of the action potential was stable at temperatures from 4 to 26°C. It decreased at temperatures above 26°C in both acclimation groups.

4. 4.|The duration of the falling phase of action potential was highly temperature dependent at low temperatures. A break in the slope of the dependence was found at about 14°C in cold-acclimated crayfish and at about 17°C in the warm-acclimated.

The effect of temperature on the duration of the egg stage of certain sciomyzid flies which predate Lymnae truncatula

1. 1. The effect of temperature on the duration of the egg stage of 3 species of sciomyzid flies was investigated at 14, 17, 20, 23 and 26°C.

2. 2. Ilione albiseta(Scopoli): the mean duration of the egg stage (m.d.e.s) decreased from 88.53 to 34.05 days as temperature increased up to 26°C. Under changing temperature conditions (14↔20°C) there was a significant retardation in the duration of the egg stage. 50–70% of conditioned embryonated eggs (i.e. eggs maintained on moist filter paper from 10 to 20 days at 23°C) hatched within 24 in a 0.1% solution of ascorbic acid. (Embryonation was judged to have taken place when the cephalopharyngeal skeleton was visible through the chorion and there was evidence of larval movement within the egg.)

3. 3. Limnia unguicornis (Scopoli): the m.d.e.s. at the 5 constant temperatures was very variable but was significantly shorter at 26°C (22.85 days) than at 14 and 17°C (29.8 and 32.48 days respectively).

4. 4. Pherbellia cinerella (Fallén): the m.d.e.s. decreased from 14.73 days at 14°C to 4.42 days to 26°C and percentage hatch was greatest at 14°C.

Loss of Symbiodinium from bleached soft corals Sarcophyton ehrenbergi, Sinularia sp. and Xenia sp.

The deleterious effects of temperature-induced coral bleaching, a process by which corals lose their endosymbiotic algae (zooxanthellae; genus Symbiodinium) primarily at temperatures above mean yearly maximums, has not been well described for alcyonacean soft corals (Coelenterata, Octocorallia). The study of Symbiodinium cells lost from Sarcophyton ehrenbergi, Sinularia sp., and Xenia sp., which have not been compared in bleaching studies, indicate that the soft coral S. ehrenbergi released the greatest number of symbiont cells, however, it was less susceptible to heat stress surviving temperatures of 34 °C for >39 h. Sinularia sp. showed intermediate levels of bleaching tolerance to elevated temperatures, surviving prolonged exposures at 32 °C, but dying within 24 h at 34 °C. Xenia sp., however, was the most vulnerable to high heat stress maximally releasing Symbiodinium at temperatures ≤30 °C. This evidence indicates that Xenia sp. is even more susceptible to elevated temperatures than Acropora spp., previously reported to be the most vulnerable coral species to elevated temperature-induced bleaching.

Molecular analysis showed that the more resistant soft coral species (S. ehrenbergi) had the same type of Symbiodinium (clade C) as less resistant soft corals (Xenia sp.). In comparison to scleractinian corals collected from the same region that show similar bleaching resistance to high temperatures (e.g. Porities solida—more robust; Favites complanata—moderate resistance; Acropora hyacinthus—less robust), all scleractinian corals were symbiotic with Symbiodinium from clade C. A. hyacinthus, however, was found to possess multiple symbionts (clades B and C), and this represents a first report of Clade B in any Acropora species.     

Biosynthesis and properties of an extracellular metalloprotease from the Antarctic marine bacterium Sphingomonas paucimobilis

An extracellular protease from the marine bacterium Sphingomonas paucimobilis, strain 116, isolated from the stomach of Antarctic krill, Euphausia superba Dana, was purified and characterized. The excretion of protease was maximal at temperatures from 5 to 10°C, i.e. below the temperature optimum for the strain growth (15°C). The highly purified enzyme was a metalloprotease [sensivity to ethylenediaminetetraacetic acid (EDTA)] and showed maximal activity against proteins at 20–30°C and pH 6.5–7.0, and towards N-benzoyl-tyrosine ethyl ester (BzTyrOEt) at pH 8.0. At 0°C the enzyme retained as much as 47% of maximal activity in hydrolysis of urea denatured haemoglobin (Hb) (at pH 7.0), and at −5 and −10°C, 37 and 30%, respectively. The metalloprotease was stable up to 30°C for 15 min and up to 20°C for 60 min. These results indicate that the proteinase from S. paucimobilis 116 is a cold-adapted enzyme.     

Non-shivering thermogenesis in winter-acclimatized and in long-scotophase and cold-acclimated Apodemus mystacinus (Rodentia)

1. 1.|Resistance to cold through non-shivering thermogenesis (the absolute increase in O₂ consumption caused by noradrenaline injection) was increased 3-fold in individuals of the broad-toothed mouse A. mystacinus, kept for 3 weeks under a short photoperiod (long scotophase 8L:16D) at an ambient temperature of 28°C, compared to control conditions (12L:12D; 28°C), and did not differ significantly from the winter-acclimatized group.

2. 2.|Acclimation of the same individuals to long scotophase and cold (8L:16d; 7°C) caused a significant (P < 0.01) increase in absolute O₂ consumption and maximal body temperature, as a response to noradrenaline injectin, when compared to long-scotophase individuals (8L:16D; 28°C).

3. 3.|The results of this study support the idea that winter acclimatization of heat-production mechanisims may be induced by the extension of scotophase, which cycles very regulary in nature and in the Mediterranean region occurs before the beginning of the cold season.

Influence of pregnancy on locomotor and feeding performances of the skink, Mabuya multifasciata: why do females shift thermal preferences when pregnant?

It has been documented in the many-lined sun skink (Mabuya multifasciata) that pregnant females select lower body temperatures (27.6–30.8 °C) than do nonpregnant females and adult males (29.7–35.7 °C). We therefore used the skink to test the hypothesis that the maximization of reproductive benefits should be achieved in pregnant females by shifting thermal preferences towards the levels optimal for embryonic development but entailing relatively small costs of reproduction. Data on adult males showed that temperatures maximizing swimming stamina (indicative of locomotor endurance) fell within the range of body temperatures selected by nonpregnant females and adult males. Data on swimming stamina and feeding performance of pregnant females, nonpregnant females and adult males measured at 26 and 30 °C showed that: (1) pregnancy impaired locomotor and feeding performances, but such impairments did not persist after parturition; (2) the degree of locomotor impairment during pregnancy was greater at 26 °C than at 30 °C, but the degree of feeding impairment during pregnancy was greater at 30 °C than at 26 °C. Pregnant females of M. multifasciata selecting body temperatures at about 29 °C could not only produce good-quality offspring in a relatively short gestation length but also reduce reproductive costs associated with locomotor and feeding impairments to some extent. Thus, data from M. multifasciata validate the above hypothesis.     

Temperature dependence of the germination of tomato seeds

1. 1.|The germination of tomato “C38” seeds exposed to periodical white incandescent light occurs from 6.0° ± 0.2°C to 37.5° ± 0.2°C, being rate-limited for 10.3° T 25.9°C, and elsewhere limited by the germination capacity.

2. 2.|Rate averages are linearly T-dependent outside their optimum range (25.9° T 29.5°C) and rate variances are typically heterogeneous.

3. 3.|The smooth curvilinear Arrhenius plot indicates that diffusion processes cannot be rate-limiting outside the interval 25.9° T 29.5°C, whereas phase transitions and (or) transconformation of proteins may limit the rate above 34.9°C and, by opposite effects, below 15.3°C.

4. 4.|The thermal communication between the environment and the germinating seed proceeds by a temperature signal which is quenched by random thermal noise at T 11.2°C and at T 34.0°C.

Metabolic characteristics of sea cucumber Apostichopus japonicus (Selenka) during aestivation

Metabolic characteristics of the sea cucumber Apostichopus japonicus (Selenka) during aestivation were studied in the laboratory. The effects of water temperature on oxygen consumption rate (OCR) and ammonia-N excretion rate (AER) in A. japonicus were determined by the Winkler and Hypobromite methods, respectively. Mature (large, 148.5 ± 15.4 g, medium 69.3 ± 6.9 g) and immature (small, 21.2 ± 4.7 g) individuals aestivated at water temperatures of 20 and 25 °C, respectively. The metabolic characteristics of mature individuals were different from immature individuals during this period. The OCR of mature sea cucumbers peaked at 20 °C, and then dropped significantly at higher temperatures, whereas the OCR of the immature animals continued to increase slightly, even beyond the aestivation temperature. The AER of mature individuals peaked at 20 °C, while that of the immature animals peaked at 25 °C. The relationships between dry weight (DW) and absolute oxygen consumption (R) and absolute ammonia-N excretion (N) could be described by the regression equation R or N = aW^b. With the exception of 15 °C, the O / N ratios (calculated in atomic equivalents) of large size sea cucumbers was close to 20 across the temperatures used in this study, indicating that their energy source was a combination of lipid and protein. On the other hand, apart from small individuals maintained at 10 °C, the O / N ratios of the medium and small sea cucumbers were close to 10, indicating that protein was their major energy source. The O / N ratios in all size groups remained unchanged after aestivation was initiated.     

Effect of developmental temperature stress on fluctuating asymmetry in certain morphological traits in Drosophila ananassae

In the present study, the effect of thermal stress on the variability and fluctuating asymmetry (FA) in different morphological traits, viz., thorax length (TL), sternopleural bristle number (SBN), wing length (WL), wing-to-thorax (W/T) ratio, sex comb tooth number (SCTN) and ovariole number (ON), was investigated in 10 isofemale lines of Drosophila ananassae. The phenotypic and genetic variability is higher in the flies reared at low (20 °C) and at high (30 °C) temperatures as compared to that of standard (25 °C) temperature. Further, the levels of FA of measured traits differed significantly among the three temperature regimes except SBN and SCTN in males and SBN and W/T ratio in females. Moreover, the magnitude of positional fluctuating asymmetry is similar in males reared at three different developmental temperatures for SBN and SCTN but it varies significantly for SBN in females. However, when FA across all the traits was combined into a composite index (CFA), significant differences were found for both temperature regimes and sexes. Males showed higher CFA at 30 °C whereas in females it was higher at 20 °C. The results suggest that temperature increases the levels of variability and FA but the effect seems to be trait and sex specific in D. ananassae.