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1.
Titis Wijayanto Hitoshi Wakabayashi Joo-Young Lee Nobuko Hashiguchi Mohamed Saat Yutaka Tochihara 《International journal of biometeorology》2011,55(4):491-500
The objective of this study was to investigate thermoregulatory responses to heat in tropical (Malaysian) and temperate (Japanese)
natives, during 60 min of passive heating. Ten Japanese (mean ages: 20.8 ± 0.9 years) and ten Malaysian males (mean ages:
22.3 ± 1.6 years) with matched morphological characteristics and physical fitness participated in this study. Passive heating
was induced through leg immersion in hot water (42°C) for 60 min under conditions of 28°C air temperature and 50% RH. Local
sweat rate on the forehead and thigh were significantly lower in Malaysians during leg immersion, but no significant differences
in total sweat rate were observed between Malaysians (86.3 ± 11.8 g m−2 h−1) and Japanese (83.2 ± 6.4 g m−2 h−1) after leg immersion. In addition, Malaysians displayed a smaller rise in rectal temperature (0.3 ± 0.1°C) than Japanese
(0.7 ± 0.1°C) during leg immersion, with a greater increase in hand skin temperature. Skin blood flow was significantly lower
on the forehead and forearm in Malaysians during leg immersion. No significant different in mean skin temperature during leg
immersion was observed between the two groups. These findings indicated that regional differences in body sweating distribution
might exist between Malaysians and Japanese during heat exposure, with more uniform distribution of local sweat rate over
the whole body among tropical Malaysians. Altogether, Malaysians appear to display enhanced efficiency of thermal sweating
and thermoregulatory responses in dissipating heat loss during heat loading. Thermoregulatory differences between tropical
and temperate natives in this study can be interpreted as a result of heat adaptations to physiological function. 相似文献
2.
People adapt to thermal environments, such as the changing seasons, predominantly by controlling the amount of clothing insulation, usually in the form of the clothing that they wear. The aim of this study was to determine the actual daily clothing insulation on sedentary human subjects across the seasons. Thirteen females and seven males participated in experiments from January to December in a thermal chamber. Adjacent months were grouped in pairs to give six environmental conditions: (1) January/February = 5°C; (2) March/April = 14°C; (3) May/June = 25°C; (4) July/August = 29°C; (5) September/October = 23°C; (6) November/December = 8°C. Humidity(45 ± 5%) and air velocity(0.14 ± 0.01 m/s) were constant across all six experimental conditions. Participants put on their own clothing that allowed them to achieve thermal comfort for each air temperature, and sat for 60 min (1Met). The clothing insulation (clo) required by these participants had a significant relationship with air temperature: insulation was reduced as air temperature increased. The range of clothing insulation for each condition was 1.87–3.14 clo at 5°C(Jan/Feb), 1.62–2.63 clo at 14°C(Mar/Apr), 0.87–1.59 clo at 25°C(May/Jun), 0.4–1.01 clo at 29°C(Jul/Aug), 0.92–1.81 clo at 23°C (Sept/Oct), and 2.12–3.09 clo at 8°C(Nov/Dec) for females, and 1.84–2.90 clo at 5°C, 1.52–1.98 clo at 14°C, 1.04–1.23 clo at 25°C, 0.51–1.30 clo at 29°C, 0.82–1.45 clo at 23°C and 1.96–3.53 clo at 8°C for males. The hypothesis was that thermal insulation of free living clothing worn by sedentary Korean people would vary across seasons. For Korean people, a comfortable air temperature with clothing insulation of 1 clo was approximately 27°C. This is greater than the typical comfort temperature for 1 clo. It was also found that women clearly increased their clothing insulation level of their clothing as winter approached but did not decrease it by the same amount when spring came. 相似文献
3.
J. A. MacDonald K. B. Storey 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1998,168(7):513-525
Arousal from hibernation requires thermogenesis in brown adipose tissue, a process that is stimulated by β-adrenergic signals,
leading to a rise in intracellular 3′,5′-cyclic adenosine monophosphate AMP (cAMP) and activating cAMP-dependent protein kinase
A (PKA) to phosphorylate a suite of target proteins and activate lipolysis and uncoupled respiration. To determine whether
specific adaptations (perhaps temperature-dependent) facilitate PKA kinetic properties or protein-phosphorylating ability,
the catalytic subunit of PKA (PKAc) from interscapular brown adipose of the ground squirrel Spermophilus richardsonii, was purified (final specific activity = 279 nmol phosphate transferred per min per mg protein) and characterized. Physical
properties of PKAc included a molecular weight of 41 kDa and an isoelectric point of 7.8 ± 0.08. A change in assay temperature
from a euthermic value (37 °C) to one typical of hibernating body temperature (5 °C) had numerous significant effects on ground
squirrel PKAc including: (a) pH optimum rose from 6.8 at 37 °C to 8.7 at 5 °C, (b) Km values at 37 °C for Mg.ATP (49.2±3.4 M) and for two phosphate acceptors, Kemptide (50.0±5.5 M) and Histone IIA (0.41 ± 0.05 mg/ml)
decreased by 53%, 80% and 51%, respectively, at 5 °C, and (c) inhibition by KCl, NaCl and NH4Cl was reduced. However, temperature change had little or no effect on Km values of rabbit PKAc, suggesting a specific positive thermal modulation of the hibernator enzyme. Arrhenius plots also differed
for the two enzymes; ground squirrel PKAc showed a break in the Arrhenius relationship at 9 °C and activation energies that
were 29.1 ± 1.0 kJ/mol for temperatures >9 °C and 2.3-fold higher at 68.1 ± 2.1 kJ/mol for temperatures <9 °C, whereas the
rabbit enzyme showed a breakpoint at 17 °C with a 13-fold higher activation energy over the lower temperature range. However,
fluorescence analysis of PKAc in the absence of substrates, showed a linear change in fluorescence intensity and wavelength
of maximal fluorescence over the entire temperature range; this suggested that the protein conformational change indicated
by the break in the Arrhenius plot was substrate-related. Temperature change also affected the Hill coefficient for cAMP dissociation
of the ground squirrel PKA holoenzyme which rose from 1.12 ± 0.18 at 37 °C to 2.19 ± 0.07 at 5 °C, making the release of catalytic
subunits at low temperature much more responsive to small changes in cAMP levels. Analysis of PKAc function via in vitro incubations
of extracts of ground squirrel brown adipose with 32P-ATP + cAMP in the presence versus absence of a PKA inhibitor, also revealed major differences in the patterns of phosphoproteins,
both between euthermic and hibernating animals as well as between 37 and 5 °C incubation temperatures; this suggests that
there are both different targets of PKAc phosphorylation in the hibernating animal and that temperature affects the capacity
of PKAc to phosphorylate different targets. Both of these observations, plus the species-specific and temperature-dependent
changes in ground squirrel PKAc kinetic properties, suggest differential control of the enzyme in vivo at euthermic versus
hibernating body temperatures in a manner that would facilitate a rapid and large activation of the enzyme during arousal
from torpor.
Accepted: 10 July 1998 相似文献
4.
Lovegrove G Körtner G Geiser F 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1999,169(1):11-18
The costs of arousal from induced torpor were measured in the striped-faced dunnart (Sminthopsis macroura; ca. 25 g) under two experimental ambient temperature cycles. The sinusoidal-type temperature cycles were designed to evaluate
the effects of passive, ambient temperature heating during arousal from torpor in these insectivorous marsupials. It was hypothesised
that diel ambient temperature cycles may offer significant energy savings during arousal in animals that employ daily torpor
in summer as a response to unpredictable food availability. The cost of arousal in animals in which passive, exogenous heating
occurred was significantly lower than that in animals not exposed to an ambient temperature cycle. The total cost of all three
phases of torpor (entry, maintenance and arousal) was almost halved when animals were exposed to an ambient heating cycle
from 15 °C to 25 °C over a 24-h period. In all animals, irrespective of the experimental ambient temperature cycle employed,
the minimum torpor body temperature was 17–18 °C. The body temperature (Tb) of animals exposed to exogenous heating increased from the torpor Tb minimum to a mean value of 22.59 °C before endogenous heat production commenced. This relatively small increase in Tb of ca. 5 °C through `free' passive heating was sufficient to account for the significant ca. three-fold decrease in the cost
of arousal and may represent an important energetic aid to free-ranging animals.
Accepted: 4 October 1998 相似文献
5.
Migration and reproduction of the Caspian Lamprey, Caspiomyzon wagneri, in the Shirud River were investigated during late-March to early-May at water temperatures ranging from 11 to 21.25°C. We
examined the effect of water temperature on timing of spawning migrations. There was a significant negative relationship between
temperature and intensive migration of Caspian Lamprey (p < 0.05). The most intensive migration of lampreys was at night (21:00–3:00 h) and when the water temperatures averaged 16°C
(34.43%). The overall sex ratio (male to female) was 1.07 to 1. The individual absolute fecundity was 31 ‘758–51’ 198 eggs
(mean±SD—41,924 ± 5,382). The egg diameter was 0.780–1.151 (0.92 ± 0.081) mm. The individual relative fecundity varies from
80.3 to 148.1 (107.2 ± 15.1) eggs per 1 mm of length and from 260.8 to 677.4 (397.6 ± 93) eggs per 1 g of weight. The gonadosomatic
index (GSI) of females was 5.83–31.44 (11.22 ± 4.30). 相似文献
6.
Satoshi Suzuki Kazushige Furuya Tadashi Kawai Ichiro Takeuchi 《Journal of applied phycology》2008,20(5):833-844
Recent studies on global climate change report that increase in seawater temperature leads to coastal ecosystem change, including
coral bleaching in the tropic. In order to assess the effect of increased seawater temperature on a temperate coastal ecosystem,
we studied the inter-annual variation in productivity of Laminaria japonica using long-term oceanographic observations for the Uwa Sea, southern Japan. The annual productivity estimates for L. japonica were 2.7 ± 2.5 (mean ± SD) kg wet wt. m−1 (length of rope) (2003/2004), 1.0 ± 0.6 kg wet wt. m−1 (2004/2005) and 12.1 ± 12.5 kg wet wt. m−1 (2005/2006). Our previous study using the same methodology at the same locality reported that the productivity was estimated
for the 2001/2002 (33.3 ± 15.2 kg wet wt. m−1) and 2002/2003 (34.0 ± 8.7 kg wet wt. m−1) seasons. Productivity in 2003/2004 and 2004/2005 was significantly lower than in years 2001/2002, 2002/2003 and 2005/2006.
A comparison of oceanographic conditions among the 5 years revealed the presence of threshold seawater temperature effects.
When the average seawater temperature during the first 45 days of each experiment exceeded 15.5°C, productivity was reduced
to about 10 % of that in cooler years. Moreover the analysis of growth and erosion rates indicates that when the seawater
temperature was over 17.5°C, erosion rate exceeded growth rate. Thus, an increase of seawater temperature of just 1°C during
winter drastically reduces the productivity of L. japonica in the Uwa Sea. 相似文献
7.
Ethanol production by recombinant Escherichia coli strain FBR5 from dilute acid pretreated wheat straw (WS) by separate hydrolysis and fermentation (SHF) and simultaneous saccharification
and fermentation (SSF) was studied. The yield of total sugars from dilute acid (0.5% H2SO4) pretreated (160 °C, 10 min) and enzymatically saccharified (pH 5.0, 45 °C, 72 h) WS (86 g/l) was 50.0 ± 1.4 g/l. The hydrolyzate
contained 1,184 ± 19 mg furfural and 161 ± 1 mg hydroxymethyl furfural per liter. The recombinant E. coli FBR5 could not grow at all at pH controlled at 4.5 to 6.5 in the non-abated wheat straw hydrolyzate (WSH) at 35 °C. However,
it produced 21.9 ± 0.3 g ethanol from non-abated WSH (total sugars, 44.1 ± 0.4 g/l) in 90 h including the lag time of 24 h
at controlled pH 7.0 and 35 °C. The bioabatement of WS was performed by growing Coniochaeta ligniaria NRRL 30616 in the liquid portion of the pretreated WS aerobically at pH 6.5 and 30 °C for 15 h. The bacterium produced 21.6 ± 0.5 g
ethanol per liter in 40 h from the bioabated enzymatically saccharified WSH (total sugars, 44.1 ± 0.4 g) at pH 6.0. It produced
24.9 ± 0.3 g ethanol in 96 h and 26.7 ± 0.0 g ethanol in 72 h per liter from bioabated WSH by batch SSF and fed-batch SSF,
respectively. SSF offered a distinct advantage over SHF with respect to reducing total time required to produce ethanol from
the bioabated WS. Also, fed-batch SSF performed better than the batch SSF with respect to shortening the time requirement
and increase in ethanol yield. 相似文献
8.
Todd Sformo F. Kohl J. McIntyre P. Kerr J. G. Duman B. M. Barnes 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2009,179(7):897-902
Freeze tolerance and freeze avoidance are typically described as mutually exclusive strategies for overwintering in animals.
Here we show an insect species that combines both strategies. Individual fungus gnats, collected in Fairbanks, Alaska, display
two freezing events when experimentally cooled and different rates of survival after each event (mean ± SEM: −31.5 ± 0.2°C,
70% survival and −50.7 ± 0.4°C, 0% survival). To determine which body compartments froze at each event, we dissected the abdomen
from the head/thorax and cooled each part separately. There was a significant difference between temperature levels of abdominal
freezing (−30.1 ± 1.1°C) and head/thorax freezing (−48.7 ± 1.3°C). We suggest that freezing is initially restricted to one
body compartment by regional dehydration in the head/thorax that prevents inoculative freezing between the freeze-tolerant
abdomen (71.0 ± 0.8% water) and the supercooled, freeze-sensitive head/thorax (46.6 ± 0.8% water). 相似文献
9.
Silvana Mattiello Elena Formis Sara Barbieri 《International journal of biometeorology》2011,55(2):213-218
The present study monitored daily and seasonal variations of rectal temperature in response to different environmental temperatures
in alpacas bred in the Italian Apennines at 300 m a.s.l. In each season, the rectal temperature of 33 clinically healthy alpacas
was measured three times/day (morning, midday, afternoon). Ambient temperatures were also recorded. Rectal temperatures ranged
from a minimum value of 35.1 to a maximum of 39.4°C, with a maximum daily thermal excursion (ΔTrec) of 3.2°C. Temperatures increased throughout the day, with highly significant differences recorded in both young and adult
animals between all the time bands (P < 0.001). These differences were particularly dramatic for adults in summer, when the mean rectal temperature in the morning
was 36.3 ± 0.13°C, probably as a consequence of recent shearing. Significant ΔTrec differences were recorded depending on the season in both young and adult animals (P < 0.001), with the highest ΔTrec values recorded in summer (although the highest daily ambient excursion value was recorded in winter). In conclusion, similarly
to alpacas bred in their natural environment, alpacas bred in Italy show a wide thermal neutrality zone, which is probably
an adaptive response, that allows the animals to save energy. In the Italian Apennines, in order to prevent situations of
hypothermia, with possible detrimental effects on alpacas’ health and welfare, shearing should be carried out only in warm
seasons. 相似文献
10.
Soria F Ellenrieder G Oliveira GB Cabrera M Carvalho LB 《Applied microbiology and biotechnology》2012,93(3):1127-1134
α-l-Rhamnosidase from Aspergillus terreus was covalently immobilized on the following ferromagnetic supports: polyethylene terephthalate (Dacron-hydrazide), polysiloxane/polyvinyl
alcohol (POS/PVA), and chitosan. The powdered supports were magnetized by thermal coprecipitation method using ferric and
ferrous chlorides, and the immobilization was carried out via glutaraldehyde. The activity of the Dacron-hydrazide (0.53 nkat/μg
of protein) and POS/PVA (0.59 nkat/μg of protein) immobilized enzyme was significantly higher than that found for the chitosan
derivative (0.06 nkat/μg of protein). The activity–pH and activity–temperature profiles for all immobilized enzymes did not
show difference compared to the free enzyme, except the chitosan derivative that presented higher maximum temperature at 65 °C.
The Dacron-hydrazide derivative thermal stability showed a similar behavior of the free enzyme in the temperature range of
40–70 °C. The POS/PVA and chitosan derivatives were stable up to 60 °C, but were completely inactivated at 70 °C. The activity
of the preparations did not appreciably decrease after ten successive reuses. Apparent K
m of α-l-rhamnosidase immobilized on magnetized Dacron-hydrazide (1.05 ± 0.22 mM), POS/PVA (0.57 ± 0.09 mM), and chitosan (1.78 ± 0.24 mM)
were higher than that estimated for the soluble enzyme (0.30 ± 0.03 mM). The Dacron-hydrazide enzyme derivative showed better
performance than the free enzyme to hydrolyze 0.3% narigin (91% and 73% after 1 h, respectively) and synthesize rhamnosides
(0.116 and 0.014 mg narirutin after 1 h, respectively). 相似文献
11.
Sadaf N. Zubair Stephan J. Peake James F. Hare W. Gary Anderson 《Environmental Biology of Fishes》2012,93(4):577-587
Lake sturgeon, Acipenser fulvescens, are considered threatened or endangered throughout most of their North American Range. Current hatchery rearing for re-stocking
programs utilise conventional methods with little to no understanding of the relationship between rearing conditions and the
development of the hypothalamic-pituitary-interrenal (HPI) stress axis. In the present study we examined the effects of substrate
type and temperature on the development of the HPI stress axis in prolarval and larval lake sturgeon. Lake sturgeon raised
over either gravel or no substrate did not consistently show an increase in whole body cortisol at the prolarval stage. However,
after the onset of exogenous feeding a consistent increase in whole body cortisol following a stress was evident. Lake sturgeon
larvae raised in gravel substrate demonstrated a sustained increase in whole body cortisol for at least 240 min post stress
whereas whole body cortisol in larvae raised in no substrate returned to baseline within 240 min post stress. Lake sturgeon
larvae raised at 9, 12 and 15°C exhibited markedly different cortisol responses with baseline whole body cortisol being, 38.6 ± 3,
5.67 ± 0.41 and 25.38 ± 2.84 ng.g−1 respectively. Furthermore, the chase induced increases in whole body cortisol at the larval stage were significantly different
for each temperature treatment. These experiments demonstrate that physical environment has a significant impact on the development
of the HPI stress axis in lake sturgeon. 相似文献
12.
Dimitris G. Sfakianakis Ioannis Leris Maroudio Kentouri 《Environmental Biology of Fishes》2011,90(4):421-427
It is widely known that water temperature affects the swimming capacity of fish. But the effect of the rearing temperature
on the swimming ability of the fish at later stages, has not had similar attention. In this study, four populations of zebrafish,
were reared in different water temperatures (22, 25, 28 and 31°C) and after being acclimatized in a common temperature (26.5°C)
for over a month, they were subjected to swimming trials in order to evaluate the maximum relative critical velocity (RU
crit
) in each case. Fish that were reared in 22°C showed statistically significant lower performance than the ones reared in 31°C
(7.72 ± 0.17 vs. 8.79 ± 0.28, means ± S.E.). Possible explanations for the observed differentiation could be the effect of
early life temperature on fish muscle ontogeny or on body shape. 相似文献
13.
Jeffrey R. Ziegeweid Cecil A. Jennings Douglas L. Peterson 《Environmental Biology of Fishes》2008,82(3):299-307
Many populations of shortnose sturgeon, Acipenser brevirostrum, in the southeastern United States continue to suffer from poor juvenile recruitment. High summer water temperatures, which
may be exacerbated by anthropogenic activities, are thought to affect recruitment by limiting available summer habitat. However,
information regarding temperature thresholds of shortnose sturgeon is limited. In this study, the thermal maximum method and
a heating rate of 0.1°C min−1 was used to determine critical and lethal thermal maxima for young-of-the-year (YOY) shortnose sturgeon acclimated to temperatures
of 19.5 and 24.1°C. Fish used in the experiment were 0.6 to 35.0 g in weight and 64 to 140 days post hatch (dph) in age. Critical
thermal maxima were 33.7°C (±0.3) and 35.1°C (±0.2) for fish acclimated to 19.5 and 24.1°C, respectively. Critical thermal
maxima significantly increased with an increase in acclimation temperature (p < 0.0001). Lethal thermal maxima were 34.8°C (±0.1) and 36.1°C (±0.1) for fish acclimated to 19.5 and 24.1°C, respectively.
Lethal thermal maxima were significantly affected by acclimation temperature, the log10 (fish weight), and the interaction between log10(fish weight) and acclimation temperature (p < 0.0001). Thermal maxima were used to estimate upper limits of safe temperature, thermal preferences, and optimal growth
temperatures of YOY shortnose sturgeon. Upper limits of safe temperature were similar to previous temperature tolerance information
and indicate that summer temperatures in southeastern rivers may be lethal to YOY shortnose sturgeon if suitable thermal refuge
cannot be found. 相似文献
14.
Studies were carried out to utilize in situ proteases of shrimp heads to recover carotenoproteins possessing antioxidant activity.
Highest protease activity of the buffer extract was found at pH 8.0 (9.85 ± 0.61 units). The protease activity increased with
temperature up to 50°C and reduced thereafter with highest activity being 19.32 ± 2.0 units. Thus, the autolysis of shrimp
heads for recovery of carotenoprotein was carried out at pH 8.0 and at 50°C. Waste to buffer ratio had a significant (p < 0.05)
effect on recovery of carotenoids in carotenoprotein filtrate with a maximum of 58.5 ± 6.4% recovery with a waste to buffer
ratio of 1:2.5 (w:v). The carotenoid recovery increased significantly to 63.4% ± 3.6% at the end of a 4-h autolysis. The studies on combined
effect of waste to buffer ratio and autolysis time indicated increase in protein recovery with increase in waste to buffer
ratio but not with autolysis time. DPPH scavenging activity of the carotenoprotein isolate increased with autolysis time up
to 100 min, and thereafter, reduced above 160 min of autolysis time. With increase in waste to buffer ratio, the scavenging
activity increased, reaching more than 12.5 mg TBHQ equivalent/mg protein at waste to buffer ratio of 1:5. The optimum autolysis
condition for obtaining antioxidant activity rich carotenoprotein from shrimp heads was found to be waste to buffer (pH 8.0)
ratio of 1:5 and an autolysis time of 2 h at 50°C. The isolated carotenoprotein was found to have antioxidant activity with
respect to singlet oxygen quenching, reducing power and metal chelating activity. 相似文献
15.
Geiser F Brigham RM 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2000,170(2):153-162
Previous studies have suggested that Australian long-eared bats (Nyctophilus) differ from northern-hemisphere bats with respect to their thermal physiology and patterns of torpor. To determine whether
this is a general trait of Australian bats, we characterised the temporal organisation of torpor and quantified metabolic
rates and body temperatures of normothermic and torpid Australian bats (Nyctophilus geoffroyi, 7 g and N. gouldi, 10 g) over a range of air temperatures and in different seasons. The basal metabolic rate of normothermic bats was 1.36 ± 0.17 ml g−1 h−1 (N. geoffroyi) and 1.22 ± 0.13 ml g−1 h−1 (N. gouldi), about 65% of that predicted by allometric equations, and the corresponding body temperature was about 36 °C. Below an air
temperature of about 25 °C bats usually remained normothermic for only brief periods and typically entered torpor. Arousal
from torpor usually occurred shortly after the beginning of the dark phase and torpor re-entry occurred almost always during
the dark phase after normothermic periods of only 111 ± 48 min (N. geoffroyi) and 115 ± 66 min (N. gouldi). At air temperatures below 10 °C, bats remained torpid for more than 1 day. Bats that were measured overnight had steady-state
torpor metabolic rates representing only 2.7% (N. geoffroyi) and 4.2% (N. gouldi) of the basal metabolic rate, and their body temperatures fell to minima of 1.4 and 2.3 °C, respectively. In contrast, bats
measured entirely during the day, as in previous studies, had torpor metabolic rates that were up to ten times higher than
those measured overnight. The steady-state torpor metabolic rate of thermoconforming torpid bats showed an exponential relationship
with body temperature (r
2 = 0.94), suggesting that temperature effects are important for reduction of metabolic rate below basal levels. However, the
75% reduction of metabolic rate between basal metabolic rate and torpor metabolic rate at a body temperature of 29.3 °C suggests
that metabolic inhibition also plays an important role. Torpor metabolic rate showed little or no seasonal change. Our study
suggests that Australian Nyctophilus bats have a low basal metabolic rate and that their patterns of torpor are similar to those measured in bats from the northern
hemisphere. The low basal metabolic rate and the high proclivity of these bats for using torpor suggest that they are constrained
by limited energy availability and that heterothermy plays a key role in their natural biology.
Accepted: 22 November 1999 相似文献
16.
Andreas Gutzwiller 《Mycotoxin Research》2010,26(3):211-215
A diet contaminated with 2.8 mg deoxynivalenol (DON)/kg was fed at 6 kg per day to 32 mycotoxin-exposed pluriparous sows (M)
during lactation. The 31 control sows (C) received 6 kg of an uncontaminated diet. Although more contaminated diet was refused
(P = 0.05), DON exposure had no effect (P > 0.1) on body weight loss of the sows during lactation (M: 27.9 ± 12.3 kg; C: 29.7 ± 10.2 kg), the number of weaned piglets
(M: 9.8 ± 1.4; C: 9.7 ± 1.6) and their daily weight gain (M: 266 ± 70 g; C: 272 ± 64 g). Several sows were culled after weaning
for reasons unrelated to the experiment. Compared with the remaining 21 C sows, the remaining 26 M sows had an identical interval
between weaning and the next farrowing (M: 120 ± 1 days; C: 120 ± 1 days) and a similar litter size (M: 14.5 ± 2.7; C: 14.9 ± 3.0;
P > 0.10). The daily intake of 17 mg DON during lactation thus did not affect the reproductive performance of the sows. 相似文献
17.
Rats place their tails underneath their body trunks when cold (tail-hiding behavior). The aim of the present study was to
determine whether this behavior is necessary to maintain body temperature. Male Wistar rats were divided into ‘fed’ and ‘42-h
fasting’ groups. A one-piece tail holder (8.4 cm in length) that prevented the tail-hiding behavior or a three-piece tail
holder (2.8 cm in length) that allowed for the tail-hiding behavior was attached to the tails of the rats. The rats were exposed
to 27°C for 180 min or to 20°C for 90 min followed by 15°C for 90 min with continuous body temperature and oxygen consumption
measurements. Body temperature decreased by −1.0 ± 0.1°C at 15°C only in the rats that prevented tail-hiding behavior of the
42-h fasting group, and oxygen consumption increased at 15°C in all animals. Oxygen consumption was not different between
the rats that prevented tail-hiding behavior and the rats that allowed the behavior in the fed and 42-h fasting groups under
ambient conditions. These results show that the tail-hiding behavior is involved in thermoregulation in the cold in fasting
rats. 相似文献
18.
Acinetobacter sp. XMZ-26 (ACCC 05422) was isolated from soil samples obtained from glaciers in Xinjiang Province, China. The partial nucleotide
sequence of a lipase gene was obtained by touchdown PCR using degenerate primers designed based on the conserved domains of
cold-adapted lipases. Subsequently, a complete gene sequence encoding a 317 amino acid polypeptide was identified. Our novel
lipase gene, lipA, was overexpressed in Escherichia coli. The recombinant protein (LipA) was purified by Ni-affinity chromatography, and then deeply characterised. The LipA resulted
to hydrolyse pNP esters of fatty acids with acyl chain length from C2 to C16, and the preferred substrate was pNP octanoate showing a k
cat = 560.52 ± 28.32 s−1, K
m = 0.075 ± 0.008 mM, and a k
cat/K
m = 7,377.29 ± 118.88 s−1 mM−1. Maximal LipA activity was observed at a temperature of 15°C and pH 10.0 using pNP decanoate as substrate. That LipA peaked at such a low temperature and remained most activity between 5°C and 35°C indicated
that it was a cold-adapted enzyme. Remarkably, this lipase retained much of its activity in the presence of commercial detergents
and organic solvents, including Ninol, Triton X-100, methanol, PEG-600, and DMSO. This cold-adapted lipase may find applications
in the detergent industry and organic synthesis. 相似文献
19.
The purpose of the following research was to improve the original Celsior solution in order to obtain a higher degree of stability
and effectiveness. The solution was modified by the addition of selected antioxidants such as vitamin C, cysteine, and fumaric
acid in the following concentrations: 0.1, 0.3, and 0.5 mmol/l. The solution’s stability was estimated using an accelerated
stability test based on changes in histidine concentrations in the solution using Pauly’s method for determining concentrations.
Elevated temperatures, the factor accelerating substances’ decomposition reaction rate, were used in the tests. The research
was conducted at four temperatures at intervals of 10°C: 60 ± 0.2°C, 70 ± 0.2°C, 80 ± 0.2°C, and 90 ± 0.2°C. It was stated
that the studied substances’ decomposition occurred in accordance with the equation for first-order reactions. The function
of the logarithmic concentration (log%C) over time was revealed to be rectilinear. This dependence was used to determine the kinetics of decomposition reaction rate
parameters (the rate constant of decomposition k, activation energy E
a, and frequency factor A). On the basis of these parameters, the stability of the modified solution was estimated at +5°C. The results obtained show
that the proposed antioxidants have a significant effect on lengthening the Celsior solution’s stability. The best results
were reached when combining two antioxidants: vitamin C and cysteine in 0.5 mmol/l concentrations. As a result, the Celsior
solution’s stability was lengthened from 22 to 299 days, which is 13.5 times. Vitamin C at a concentration of 0.5 mmol/l increased
the solution’s stability by 5.2 times (t
90 = 115 days), cysteine at a concentration of 0.5 mmol/l caused a 4.4 times stability increase (t
90 = 96 days), and fumaric acid at a concentration of 0.5 mmol/l extended the stability by 2.1 times (t
90 = 48 days) in relation to the original solution. 相似文献
20.
Wilson RS James RS Johnston IA 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2000,170(2):117-124
Among amphibians, the ability to compensate for the effects of temperature on the locomotor system by thermal acclimation
has only been reported in larvae of a single species of anuran. All other analyses have examined predominantly terrestrial
adult life stages of amphibians and found no evidence of thermal acclimatory capacity. We examined the ability of both tadpoles
and adults of the fully aquatic amphibian Xenopus laevis to acclimate their locomotor system to different temperatures. Tadpoles were acclimated to either 12 °C or 30 °C for 4 weeks
and their burst swimming performance was assessed at four temperatures between 5 °C and 30 °C. Adult X. laevis were acclimated to either 10 °C or 25 °C for 6 weeks and their burst swimming performance and isolated muscle performance
was determined at six temperatures between 5 °C and 30 °C. Maximum swimming performance of cold-acclimated X. laevis tadpoles was greater at cool temperatures and lower at the highest temperature in comparison with the warm-acclimated animals.
At the test temperature of 12 °C, maximum swimming velocity of tadpoles acclimated to 12 °C was 38% higher than the 30 °C-acclimation
group, while at 30 °C, maximum swimming velocity of the 30 °C-acclimation group was 41% faster than the 12 °C-acclimation
group. Maximum swimming performance of adult X. laevis acclimated to 10 °C was also higher at the lower temperatures than the 25 °C acclimated animals, but there was no difference
between the treatment groups at higher temperatures. When tested at 10 °C, maximum swimming velocity of the 10 °C-acclimation
group was 67% faster than the 25 °C group. Isolated gastrocnemius muscle fibres from adult X. laevis acclimated to 10 °C produced higher relative tetanic tensions and decreased relaxation times at 10 °C in comparison with
animals acclimated to 25 °C. This is only the second species of amphibian, and the first adult life stage, reported to have
the capacity to thermally acclimate locomotor performance.
Accepted: 28 October 1999 相似文献