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PubMed2004

Breeding season in female cats acclimated under a natural photoperiod and interval until puberty.

The breeding season was investigated in 174 female cats that were acclimated under a natural photoperiod, and determined the interval between birth and initial estrus (puberty) was determined in 125 cats. Although the breeding season differed noticeably among individual animals, the mean was 180.4 +/- 3.0 (SE) days between the end of January and the end of July. The interval between birth and first estrus ranged from 181 to 560 days, with a mean of 345.0 +/- 0.9 days. With respect to month of birth, the mean interval was 343.0 +/- 9.5 days in cats born between March and June. Among cats that were born between July and October, the mean intervals were 242.0 +/- 6.3 days in cats that exhibited estrus the year after birth and 519.2 +/- 5.8 days in those that exhibited estrus 2 years after birth.

Animals↗
PubMed2002

Cardiovascular responses to adrenergic agents in different acclimation states in the rock pigeon (Columba livia).

The effect of propranolol on heart rate (fH) was measured in season-acclimatized pigeons. Propranolol treatment decreased fH in winter-acclimatized pigeons, accelerated fH in summer-acclimatized pigeons, but had no effect on fH in spring-acclimatized pigeons. The effect of propranolol in summer-acclimatized pigeons is opposite to that observed in mammals. Interestingly, isoproterenol produced a propranolol-like cardioacceleration in heat-acclimated pigeons. We suggest that propranolol affects fH in summer-acclimatized pigeons via two opposing routes-a direct and a peripheral indirect route. We also suggest that the cardiovascular effects of propranolol are involved in the capacity of the pigeon to evaporate water from its skin.

Acclimatization↗
PubMedDate not supplied

Flavonoids and phenol carboxylic acids in the oriental medicinal plant Astragalus membranaceus acclimated in Poland.

Astragalus membranaceus (Fisch.) Bunge has been was successfully acclimated in Central Europe. We report the content of isoflavones and some other polyphenolic compounds in roots and aerial parts that have been analyzed by means of TLC and HPLC. The total amount of isoflavones in leaves, was 0.55 mg g(-1) dry weight, and of the flavonols--up to 3.54 mg g(-1). In the roots isoflavonoid content was extremely variable, but reached 3.04 mg g(-1), whereas flavonols content was 0.49 mg g(-1).

Acclimatization↗
PubMed2003

Sensitivity of cyanobacterial antenna, reaction center and CO2 assimilation transcripts and proteins to moderate UVB: light acclimation potentiates resistance to UVB.

We tested the hypothesis that cyanobacterial cells have sufficient acclimation potential to tolerate UVB when it is applied in a natural quantum ratio to growth photosynthetically active radiation (PAR). We grew Synechococcus under 50 (Low) or 300 (High) micromol PAR m(-2) x s(-1) and then exposed the cells to 0.125 (Low) or 0.75 (High) micromol UVB m(-2) x s(-1). The PAR:UVB quantum ratios were near natural for both the Low-PAR:Low-UVB and the High-PAR:High-UVB treatments, but UVB was in excess of typical aquatic PAR:UVB for Low-PAR:High-UVB treatments. The cellular light history determined the UVB responses of Synechococcus. High-PAR cells initially had fewer cpc transcripts encoding phycocyanin, lower phycocyanin content, and more psbAII/AIII transcripts encoding the D1:2 photosystem II (PSII) protein isoform. Higher PAR potentiated them to tolerate an appropriate UVB level without short-term inhibition of PSII or growth. Low-PAR cells rapidly altered psbAII/AIII and cpc gene expression and tolerated appropriate Low UVB. Low-PAR:High-UVB cells, in contrast, suffered short-term inhibition of PSII and growth. In all treatments UVB induced transient loss of cpc transcripts, possibly to free resources for psbAII/AIII expression, which is important for UVB resistance. The drop in cpc transcripts was not part of a general shock response because rbcL transcript pools were stable upon UVB exposure.

Adaptation, Physiological↗
PubMed1999

Resolution and identification of Gq/G11alpha and Gialpha/Goalpha proteins in brown adipose tissue: effect of cold acclimation.

Levels of guanine nucleotide-binding proteins G(q)alpha and G(11)alpha, which produce receptor regulation of phospholipase C, were measured immunologically in purified plasma membrane fractions of hamster brown adipose tissue (BAT). This was achieved by immunoblotting with antisera (CQ series) that identify these two polypeptides equally, following separation of the plasma membranes using SDS-PAGE in the presence of 6 M urea, i.e. conditions that can resolve G(q)alpha and G(11)alpha. The ratio of levels of G(q)alpha to G(11)alpha was 1:1. A similar approach was used for resolution and identification of G(o)1alpha and G(o)2alpha, the latter representing the prevailing form of G(o)alpha proteins in this tissue. Although clearly recognized in brain microsomes, which were used as positive controls, no detected levels of G(o)*alpha protein were noted. Using specific anti-peptide antibodies directed against the carboxy-terminal decapeptide of G(i)3alpha, this G protein was also found to be expressed in BAT tissue. Cold acclimation resulted in reduction of the plasma membrane levels of all these Galpha proteins.

Adaptation, Physiological↗
PubMed2005

Effects of hardness, chloride, and acclimation on the acute toxicity of sulfate to freshwater invertebrates.

The acute toxicity of sulfate to Ceriodaphnia dubia, Chironomus tentans, Hyalella azteca, and Sphaerium simile was assessed to support potential updates of Illinois (USA) sulfate criteria for the protection of aquatic life. The mean lethal concentrations to 50% of a sample population (LC50s), expressed as mg S04(-2)/L, in moderately hard reconstituted water (MHRW) were as follows: 512 mg/L for H. azteca, 2,050 mg/L for C. dubia, 2,078 mg/L for S. simile, and 14,134 mg/L for C. tentans. At constant sulfate (approximately 2,800 mg/L) and hardness (106 mg/L), survival of H. azteca was positively correlated with chloride concentration. Hardness also was found to ameliorate sodium sulfate toxicity to C. dubia and H. azteca, with LC50s for C. dubia increasing from 2,050 mg SO4(-2)/L at hardness = 90 mg/L to 3,516 mg SO4(-2)/L at hardness = 484 mg/L. Using a reformulated MHRW with a similar hardness but higher chloride concentration and different calcium to magnesium ratio than that in standard MHRW, the mean LC50 for H. azteca increased to 2,855 mg/L, and the LC50 for C. dubia increased to 2,526 mg/L. Acclimation of C. dubia to 500 and 1,000 mg SO4(-2)/L for several generations nominally increased mean LC50 values compared with those cultured in standard MHRW.

Animals↗
PubMed2006

Adaptive changes in TEF-1 gene expression during cold acclimation in the medaka.

How animals adaptively respond to a cold or hot environment has been questioned for a long time. Recently, with the aid of microarray analysis, various temperature-sensitive genes have been identified in several species. However, a definitive hypothesis regarding the mechanism of adaptation has not been proposed. In the present study, we surveyed, in medaka (Oryzias latipes), genes for which the level of expression changes depending on the surrounding temperature. A messenger RNA differential display of medaka muscle total RNA revealed one such gene encoding transcription enhancer factor-1 (TEF-1). In medaka muscle, the TEF-1 gene produces two splicing variants, TEF-1A and TEF-1B mRNAs. During cold acclimation, the mRNA level of TEF-1A decreased, whereas that of TEF-1B increased. We also found that three putative downstream genes of TEF-1, two for myosin heavy chain (MyHC) and one for troponin T (TnT), a specific group of muscle proteins, were transcribed in a temperature-dependent manner. These results suggest that the transcription of MyHC and/or TnT is regulated by TEF-1 and that these molecules participate in muscle reconstruction during temperature adaptation in fish.

Acclimatization↗
PubMed1981

Histochemical changes of rat skeletal muscles induced by cold acclimation.

After cold acclimation of rats the augmentation of succinic dehydrogenase activity in the fast-twitch oxidative glycolytic (FOG) and the slow-twitch oxidative (SO) fibers was observed in entire regions of the soleus, the extensor digitorum longus, the plantaris, the longissimus and the gastrocnemius muscles. Furthermore, a tendency to increased proportion of the FOG and the SO fibers was observed more prominently in superficial regions than in deep regions of a large muscle such as the gastrocnemius muscle.

Adaptation, Physiological↗
PubMed1981

Calorigenic and cardiovascular responses to norepinephrine in anesthetized and unanesthetized control and cold-acclimated rats.

Cardiac output (Q) and regional blood flow to various tissues were measured by gamma-labeled plastic microspheres (15 +/- 3 micrometer) injected into the left ventricle at rest and during 30-min infusion of norepinephrine (NE infusion, 2 microgram/kg.min) in either anesthetized or unanesthetized control (CT) and cold-acclimated (CA) rats. Besides cardiovascular functions, oxygen consumption (Vo2) and colonic temperature (Tcol) were measured. Under anesthesia (the rat was immersed into warm and initial Tcol was kept at around 37.6 degrees C), NE infusion produced significant increases in V02, Q and blood flow to most of the tissues measured both in CT and CA rats. The increases in V02 and blood flow to the brown adipose tissues (BAT) were significantly higher in CA rats. Both in CT and CA rats, heart rate (HR), blood pressure (BP), Q tissue blood flow, and V02 at rest were significantly higher in unanesthetized conditions (Ta 17 degrees C) than in anesthetized condition. In unanesthetized rats, these resting values were significantly higher in CT than in CA. In CT rats, NE infusion produced decreases in HR, Q and blood flow to most of the tissues measured. The reductions in blood flow to BAT and skeletal muscles were particularly consistent. In CA rats, NE infusion produced significant increases in Q and blood flow to most of the tissues measured particularly in BAT. Blood flow to the ear was decreased. Vo2 and Tco1 increased. The mass of BAT in CA rats was twice as much as that in CT animals. The result indicates that, in contrast to CT rats, CA rats can increase cardiac output and blood flow to BAT with NE in either anesthetized or unanesthetized conditions, which might be responsible for the significant calorigenic response to NE in these rats.

Acclimatization↗
PubMed1982

Hypoxic tachycardia in hypoxia-acclimated rats.

Acute hypoxia (9.5% O2) increased the heart rate (HR) in hypoxia (12% O2 for 2 months)-acclimated (HX) rats, while it decreased HR in unacclimated (CT) rats. After treatment with propranolol, acute hypoxia decreased HR to the same extent in CT and HX rats. After treatment with atropine, acute hypoxia increased HR in HX rats but not in CT rats. The hypoxia-induced tachycardia in HX rats may be mainly due to an enhanced sympatho-adrenal activity.

Acclimatization↗
PubMed1988

Effect of noradrenaline on plasma hormones and metabolites in cold-acclimated rats.

The effects of noradrenaline (NA) injection (40 micrograms/100 g, i.p.) on plasma glucagon, corticosterone (CS), deoxycorticosterone (DOCS), glucose, and free fatty acids (FFA) were investigated in cold-acclimated rats (CA) and warm controls (WC). The CA were transferred to warm control temperature ca. 18 h prior to NA or saline injection. The animals were decapitated and the trunk blood was collected 0, 10, 20, and 40 min after the injection. Plasma glucagon level increased significantly during the experimental period after NA, while saline did not influence its level. The magnitude of increase as assessed by 95% confidence interval was significantly greater in CA than in WC. Plasma CS and DOCS were significantly increased by saline injection, but NA caused greater elevations of these steroid-hormones. The magnitudes of increases were also greater in CA. In contrast to the hormonal responses, NA-induced increases of plasma glucose and FFA levels were smaller in CA than in WC. These results suggest that glucagon and glucocorticoids are released, at least partly, by NA, and these thermogenic factors act in synergism, enhancing nonshivering thermogenesis through an accelerated utilization of energy substrates such as glucose and FFA.

Acclimatization↗
PubMed1998

Adaptive changes in the thermogenesis of rats by cold acclimation and deacclimation.

Male Wistar rats, aged 6 weeks, were maintained at 25 degreesC for 9 to 11 weeks (W group), at 10 degreesC for 9 to 11 weeks (C group), and at 25 degreesC for 2 weeks after exposure to 10 degreesC for 9 weeks (D group). Thermogenesis at 10 degreesC was significantly greater than at 25 degreesC. Thermogenesis per body mass in the C group was greater than in the W and D groups. The RQ value at 10 degreesC was greater than at 25 degreesC in the W group, whereas the opposite was observed in the C and D groups. It is suggested that a large part of enhanced thermogenesis, caused by cold acclimation for 9 weeks, is lost because of a decreased secretion of calorigenic hormones, in spite of a slight decrease in BAT mass, during deacclimation for 2 weeks.

Adaptation, Physiological↗
PubMed1985

Tissue compensatory metabolic profiles in Tilapia mossambica (Peters) on acclimation to sublethal acidic and alkaline media. Gill glycogen metabolism.

Freshwater Fish, Tilapia mossambica (Peters) was acclimated to sublethal acidic and alkaline media and branchial tissue glycogen metabolism was studied. In acidic media, the glycogenolysis is elevated in the tissues and glycolysis is suppressed. In contrast, in alkaline media, the tissue glycolytic pathway is accelerated with accumulation of organic acids. In both the cases tissue had elevated G-6-PDH activity indicating stress conditions on the tissue metabolism. The tissue compensatory changes provided survival value to the fish under altered pH media.

Acclimatization↗
PubMed1996

Environmental heat stress does not reduce blood ionized calcium concentration in hens acclimated to elevated temperatures.

Changes in blood concentrations of ionized calcium and total calcium were measured in broiler breeder hens (42 wk old) relative to egg cycle and environmental temperatures. Two environmental temperature treatments were used: 1) temperature cycled daily from a low of 10 C at 0300 h to a high of 25 C at 1600 h; and 2) temperature cycled from a low of 21 C at 0300 h to a high of to a high of 39 C at 1600 h. Serial blood samples were collected from five laying hens per temperature treatment via cutaneous ulnar vein cannula beginning at the time of oviposition and every 4 h thereafter until the next oviposition. Neither blood concentration of ionized calcium nor total plasma calcium was affected by temperature. Results suggest that the supply of calcium available in blood for shell deposition is not diminished in hens acclimated to high environmental temperatures.

Adaptation, Physiological↗
PubMed1987

UV-B radiation and photosynthetic irradiance acclimate eggplant for outdoor exposure.

Treatment of greenhouse-grown eggplant (Solanum melongena L. var. esculentum Nees. 'Burpee's Black Beauty') seedlings with supplemental photosynthetically active radiation from cool-white fluorescent lamps increased growth of plants subsequently transferred outdoors relative to growth of plants that received no supplemental radiation or were shaded to 45% of solar irradiation in the greenhouse before transfer outdoors. Eggplant seedlings transferred outdoors were placed under plastic tarps either to provide relative protection from solar ultraviolet-B (UV-B) radiation (280-315 nm) using Mylar film or to allow exposure to UV-B using cellulose acetate. Protection of seedlings from UV-B radiation resulted in greater leaf expansion than for UV-B-exposed seedlings, but no change in leaf or shoot dry weight occurred after 9 days of treatment. Specific leaf weight increased in response to UV-B exposure outdoors. Exposure of eggplant to UV-B radiation from fluorescent sunlamps in the greenhouse also decreased leaf expansion and leaf and shoot dry weight gain after 5 days of treatment. However, there were no differences in leaf or shoot dry weight relative to control plants after 12 days of UV-B treatment, indicating that UV-B treated plants had acclimated to the treatment and actually had caught up with non-UV-B-irradiated plants in terms of growth.

Acclimatization↗
PubMed1998

Human cardiovascular acclimation to microgravity.

This brief review provides an update on recent studies of human cardiovascular responses to spaceflight. This report complements prior reviews of the acute responses and chronic acclimation of the cardiovascular system to actual and simulated microgravity.

Adaptation, Physiological↗
PubMed1975

Stimulation of DNA synthesis in rat liver and kidney by cold acclimation.

Exposure of adult Wistar female rats for 7 days to 4 degrees C leads to a marked increase in the weight of the liver and kidney, caused by an increased content of DNA and an increased number of cells in these organs. The weight as well as the DNA content of the cross-striated muscle do not change appreciably. Acclimation of the warmblooded rat to cold stimulates mitosis indirectly in cells capable of division, similarly as it stimulates directly the mitotic activity in mouse and human cells cultured and adapted to cold in vitro.

Acclimatization↗
PubMed2003

The effects of exertional heatstroke and exercise-heat acclimation on plasma beta-endorphin concentrations.

INTRODUCTION: It has been suggested that a proopiomelanocortin peptide beta-endorphin may play an important role in temperature regulation and therefore have specific heat stroke response patterns. METHODS: The purpose of this study was to examine the response patterns of plasma beta-endorphin at baseline, during a 7-d exercise-heat acclimation period (HA; 90 min x d(-1), 40 degrees C), and during a 6-h exercise-heat tolerance test (HTT; 6 h, 40 degrees C) performed before and after HA. Subjects were nine previously diagnosed heatstroke patients (P) and eight matched controls (C). No differences between the two groups were observed at rest, prior to HTT. RESULTS: Plasma beta-endorphin concentration in P significantly increased above resting values at 2, 4, and 6 h of HTT and were significantly greater than C responses. During HA tests, a significantly higher beta-endorphin concentration was observed in P before exercise on day 1 and day 7, but not on day 4. A significant increase occurred after exercise in both groups, on all days of HA; no differences were observed between the groups on days 4 and 7. DISCUSSION: These results demonstrate that the opioid peptide responses in individuals with recent exertional heatstroke were greater than control subjects during the initial 6-h HTT. Decreased physical training among P may have contributed to these results. However, 7 d of HA abolished these between-group differences by reducing the magnitude of beta-endorphin responses in P, indicative of an adaptation of pituitary function.

Acclimatization↗