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1.
Plasma ANP (atrial natriuretic peptide), thyroid hormones, and calcium and magnesium levels as well as heart tissue calcium
and magnesium concentrations were determined in male Wistar rats after exposure of 114 rats at low temperature (4°C) and 95
rats at high temperature (35–36°C) for 28 d. Plasma ANP, triiodothyronine (T3), thyroxine (T4), thyroid-stimulating hormone (TSH), free T3, and free T4 were estimated by radioimmunoassay, and plasma and heart tissue levels of Ca and Mg by flame atomic absorption spectrophotometry.
Results were compared to a control group exposed at 20–22°C (76 rats).
All the above parameters in control rats did not show statistically significant variations during the study. A significant
increase of plasma ANP, T3, T4, Ca, and Mg concentrations developed during cold exposure, whereas a gradual decrease of plasma ANP, T3, T4, and Mg concentrations was revealed during hot exposure. A significant increase of heart tissue Mg concentrations developed
during hot exposure. Results also indicate that plasma ANP and T3 levels are proportionally related, whereas an inverse relationship exists between plasma ANP and T3 levels and heart Mg concentrations, in both cold and hot exposed rats. In conclusion, ANP and thyroid hormones in relation
to Ca and Mg play an important role in temperature adaptation. 相似文献
2.
《农业工程》2021,41(5):424-431
Since 2007, Ulva prolifera-induced green tide occurred every year in the offshore waters of the Yellow Sea in China, which have resulted in large economic loss and heavy damage to local marine ecosystems. In addition, ocean warming and heavy metal pollution have become two main marine environmental issues in the world. However, the interactive effects of ocean warming and zinc (Zn2+) exposure on macroalgae remain poorly studied. An experiment was conducted to determine the relative growth rate (RGR) and photosynthetic performance at different temperatures (15, 20, 25 °C) and Zn2+ concentrations (0, 0.0026, 0.026, 0.26, and 0.52 mg/L). Results showed that low temperature (15 °C) increased the RGR under the medium levels of Zn2+ (0.026 mg/L) compared with high temperature (20 and 25 °C). On the other hand, at 20 and 25 °C the inhibition of Zn2+ on the PSII quantum yield and electron transport rate of U. prolifera was promoted. Furthermore, dark respiration rate increased with increases in temperature and Zn2+ concentration, while at the high temperature, the ratio of the net photosynthetic rate and dark respiration rate were (Pn/Rd) inhibited, and the inhibition was positively related to the Zn2+ concentration at ≥0.26 mg/L. in addition, the photoprotective ability was hindered under high temperature (20 and 25 °C) and the potential photosynthetic ability was restricted under higher levels of Zn2+ concentration. We conclude that ocean warming could promote the inhibition effects of heavy metal pollutions on physiological performance of U. prolifera, and probably other marine microalgae as well, on which future studies shall be conducted 相似文献
3.
Nishioka M Tanimoto K Higashi N Fukada H Ishikawa K Taya M 《Biotechnology letters》2008,30(9):1639-1643
Recombinant l-aminoacylase (PhoACY) from a hyperthermophilic archeon, Pyrococcus horikoshii, is a zinc-containing metalloenzyme. When the zinc was substituted by Mn2+ or Ni2+, its specific activity was significantly increased with acetyl-l-methionine as a substrate. The thermostability of PhoACY was improved when it was incubated with 1 mM Zn2+, Mn2+ or Ni2+. The enzyme with external Zn2+ addition had no significant loss of the activity when held at 90°C for up to 12 h and moreover had more than a 10-fold longer
half-life even at 100°C, compared to the enzyme without Zn2+ addition. A thermostable structure of the enzyme associated with zinc binding is described based on differential scanning
calorimetry. 相似文献
4.
《African Journal of Aquatic Science》2013,38(1):146-151
Trace metals such as zinc play an important role in the normal metabolic functioning of all organisms. However, metals can become toxic if background concentrations are exceeded in the environment. This study investigated the sublethal effects of zinc on the haematology of Oreochromis mossambicus at different water temperatures. Fish were exposed to sublethal zinc (Zn) concentrations of 40μg/l (mean Zn concentration measured from the Mhlathuze River) for a period of 96h at different water temperatures representing the seasonal temperatures in the Mhlathuze River (18°C, 24°C, 28°C and 32°C). Exposure to zinc at 28°C and 32°C resulted in the most pronounced haematological changes in O. mossambicus. The erythrocytotic conditions found following exposure to Zn could be attributed to damage to the gill surface. The ensuing hypoxic conditions are alleviated through the release of large amounts of immature RBC into the circulatory system. The leucocytotic conditions support the findings of damage to the gill surface. The increased glucose concentrations were attributed to a general adaptation response whereby metabolites are mobilised to meet increased energy demands during periods of stress. The changes in Na+ and K+ levels in the plasma of O. mossambicus can be attributed to a combination of stimulation of Na-K ATPase activity, reduced membrane permeability in the gill tissue and leakage from cells into the blood, respectively. 相似文献
5.
《Animal reproduction science》1987,13(2):117-131
A Zn2+-dependent protein with a special affinity for egg yolk was isolated from boar seminal plasma. It was electrophoretically homogeneous after separation on chelating Sepharose 6B, and had a subunit structure on SDS-gel electrophoresis with three fractions of molecular weights 25 000, 38 000 and 64 000. Precipitating activity toward egg yolk (optimal at pH 6.5–7.0) was stimulated by chloride ions and inhibited by a high concentration of zinc ions. The protein maintained its precipitating activity after incubation at 100°C and −196°C as well as after treatment with proteolytic enzymes. Indirect immunofluorescence showed that the Zn2+-dependent protein was secreted by epithelial cells of the seminal vesicle glands. The protein enveloped the spermatozoa after ejaculation, especially in the middle-piece area. 相似文献
6.
Anna Furmaniak 《Bioelectromagnetics》1983,4(1):55-62
Na+, K+, and Ca2+ concentrations in the blood serum and submaxillary salivary gland (SSG) were investigated in adult, male rats exposed to 2880-MHz microwaves modulated with 1.5-μs pulses at a pulse repetition rate of 1000 Hz or in a hyperthermal environment. Rats were exposed, one at a time, for 30 min to microwaves producing a specific absorption rate (SAR) of: 4.2, 6.3,6.8,8.4, 10.8, or 12.6 W/kg, or were sham exposed under similar environmental conditions. In a second series, one group of rats was exposed singly for 15, 30, or 60 min to microwaves producing an SAR of 9.5 W/kg and other rats were exposed for similar periods at 40 °C; and 10 rats were sham exposed. Flame photometric analysis indicated that the thresholds of microwave radiation required to induce a change in Na+, K+, and Ca2+ concentrations in the salivary glands are 6.8, 6.8, and 6.3 W/kg, respectively. The directions of Na+, K+, and Ca2+ ion shifts in exposed rats' salivary glands are similar, whether affected by microwaves or hyperthermia. Greater changes in Na+ and K+ concentrations in SSG of rats exposed to microwaves for 15 and 30 min were found than in those exposed at 40 °C. On the other hand, exposure to hyperthermia at 40 °C or to microwaves for 1 h caused Na+ concentration to be increased by 68.7 and 59.5% and K+ concentration to be decreased by 29.6 and 21.7%, respectively. 相似文献
7.
8.
《Comparative biochemistry and physiology. A, Comparative physiology》1994,107(2):413-421
Atlantic cod (0.8–2.5 kg) were transferred froni 8°C to 1°C seawater for 17 days. No fish died. Exposure to 1°C water produced no changes in hematocrit, or in plasma concentrations of Cl− or Mg2+. Cold water exposure caused a marked increase in plasma cortisol and glucose concentrations. Fish in 1°C seawater had higher gill Na-K-ATPase activity than fish in 8°C seawater, whereas there were no differences in gill lipid class or fatty acid composition. 相似文献
9.
Keong-Tsul Jung Han-Woo Kim Dong-Ju You Soo-Wan Nam Byung-Woo Kim Sung-Jong Jeon 《Biotechnology and Bioprocess Engineering》2012,17(6):1140-1146
A gene encoding a putative arylsulfatase from the hyperthermophilic archaeon Pyrococcus furiosus was identified, cloned, and expressed as a fusion protein with a Sce VMA intein and chitin binding domain (CBD) residue. The gene (PF1345) from P. furiosus encoding a 35 kDa protein showed some similarity (17 ~ 19%) with other arylsulfatases from the bacteria. The recombinant fusion arylsulfatase was overexpressed in E. coli and partially purified. Its molecular mass was estimated to be 90 kDa by SDS-PAGE. The optimal temperature and pH for arylsulfatase activity were found to be 45°C and 9.5, respectively. Various divalent cations (Ca2+, Mg2+, Co2+, Cu2+, Zn2+, and Mn2+) slightly activated the arylsulfatase activity in a narrow range of concentrations (below 0.5 mM), whereas Zn2+ concentrations above 2.0 mM significantly inhibited the activity. After the reaction of agar with recombinant fusion arylsulfatase for 12 h at 50°C, 75% of the sulfate in the agar was removed, and the DNA migration was greatly enhanced. Therefore, the arylsulfatase in this study could be applicable for the production of electrophoretic grade agarose by removing sulfate groups in agar. 相似文献
10.
Faouzi Herzi Natacha Jean Asma Sakka Hlaili Stéphane Mounier 《Journal of phycology》2014,50(4):665-674
We investigated the effects of zinc or lead on growth and on exudation of fluorescent dissolved organic matter (FDOM) by the marine toxic dinoflagellate Alexandrium catenella (Whedon & Kofoid) Balech. The species was exposed to increasing free zinc (1.34 × 10?7 M–3.98 × 10?6 M) or lead (5.13 × 10?9 M–1.82 × 10?7 M) concentra‐tions. Low metal levels ([Zn2+] = 1.34 × 10?7 M; [Pb2+] = 5.13 × 10?9 M) had no effect on cell growth. Toxic effects were observed from higher metal contamination ([Zn2+] = 3.98 × 10?6 M; [Pb2+] = 6.54 × 10?8 M), as a conversion of vegetative cells into cysts. Analysis of the released FDOM by three‐dimensional (3‐D) fluorescence spectroscopy was achieved, using the parallel factor analysis (PARAFAC). The PARAFAC modeling revealed four components associated with two contributions: one related to the biological activity; the other linked to the organic matter decomposition in the culture medium. The C1 component combined a tryptophan peak and characteristics of humic substances, whereas the C2 component was considered as a tryptophan protein fluorophore. The two others C3 and C4 components were associated with marine organic matter production. Relea‐sed fluorescent substances were induced by low ([Zn2+]= 1.34 × 10?7 M; [Pb2+] = 5.13 × 10?9 M) and moderate ([Zn2+] = 6.21 × 10?7 M; [Pb2+] = 2.64× 10?9 M) metal concentrations, suggesting the activation of cellular mechanisms in response to metal stress, to exudate FDOM that could complex metal cations and reduce their toxicity toward A. catenella cells. 相似文献
11.
Larry M. Gordon Richard D. Sauerheber Judy A. Esgate 《Journal of cellular biochemistry》1978,9(3):299-326
The structures of rat liver and heart plasma membranes were studied with the 5-nitroxide stearic acid spin probe, I(1 2,3). The polarity-corrected order parameters (S) of liver and heart plasma membranes were independent of probe concentration only if experimentally determined low I(1 2,3)/lipid ratios were employed. At higher probe/lipid ratios, the order parameters of both membrane systems decreased with increasing probe concentration, and these effects were attributed to enhanced nitroxide radical interactions. Examination of the temperature dependence of approximate and polarity-corrected order parameters indicated that lipid phase separations occur in liver (between 19° and 28°C) and heart (between 21° and 32°C) plasma membranes. The possibility that a wide variety of membrane-associated functions may be influenced by these thermotropic phase separations is considered. Addition of 3.9 mM CaCl2 to I(1 2,3)-labeled liver plasma membrane decreased the fluidity as indicated by a 5% increase in S at 37°C. Similarly, titrating I(1 2,3)-labeled heart plasma membranes with either CaCl2 or LaCl3 decreased the lipid fluidity at 37°C, although the magnitude of the La3+ effect was larger and occurred at lower concentrations than that induced by Ca2+; addition of 0.2 mM La3+ or 3.2 mM Ca2+ increased S by approximately 7% and 5%, respectively. The above cation effects reflected only alterations in the membrane fluidity and were not due to changes in probe–probe interactions. Ca2+ and La3+ at these concentrations decrease the activities of such plasma membrane enzymes as Na+, K+-ATPase and adenylyl cyclase, and it is suggested that the inhibition of these enzymes may be due in part to cation-mediated decreases in the lipid fluidity. 相似文献
12.
William P. Esler Evelyn R. Stimson Joan M. Jennings †Joseph R. Ghilardi †Patrick W. Mantyh John E. Maggio 《Journal of neurochemistry》1996,66(2):723-732
Abstract: The major pathological feature of Alzheimer's disease is the presence of a high density of amyloid plaques in the brain tissue of patients. The plaques are predominantly composed of human β-amyloid peptide (Aβ), a 39–43-mer peptide the neurotoxicity of which is related to its aggregation state. Previous work has demonstrated that certain metals that have been implicated as risk factors for Alzheimer's disease (Al, Fe, and Zn) also cause substantial aggregation of Aβ. In particular, we reported that zinc cations at concentrations of >10?4M dramatically accelerate the rate of Aβ aggregation at physiological peptide concentrations at 37°C in vitro. In the present study, we investigate the effect of Zn2+ on aggregation of radiolabeled and unlabeled human and rat Aβ over a wide range of peptide concentrations in the presence and absence of salt and blocking protein. Aggregation was assayed by centrifugation and filtration using amino acid analysis, immunoassay, and γ-counting for quantification over a wide range of concentrations of Zn2+ and Aβ above and below physiological values. The results of this study demonstrate the following: (a) Radio-iodinated Aβ accurately tracked unlabeled Aβ, (b) zinc concentrations of at least 10?4M were required to induce significant aggregation of Aβ, and (c) rat and human Aβ species were cleared from aqueous solutions by similar concentrations of zinc. These results stand in significant quantitative disagreement (~100-fold in zinc concentration) with one previous study that reported significant aggregation of Aβ by <1 µM Zn2+. Differences between the present study and the latter study from another laboratory appear to result from inappropriate reliance on optical density to measure Aβ concentrations and nonspecific loss of Aβ to plastic in the absence of blocking protein. 相似文献
13.
We firstly characterized zinc uptake phenomenon across basolateral membrane vesicles (BLMVs) isolated from normal rat kidney.
The process was found to be time, temperature, and substrate concentration dependent, and displayed saturability. Zn2+ uptake was competitively inhibited in the presence of 2 mM Cd with Ki of 3.9 mM. Zinc uptake was also inhibited in the presence
of sulfhydryl reacting compound suggesting involvement of {–}SH groups in the transport process. Further, to elucidate the
effect of in vivo Cd on zinc transport in BLMVs, Cd nephrotoxicity was induced by subcutaneous administration of CdCl2 at dose of 0.6 mg/kg/d for 5 days in a week for 12 weeks. An indolent renal failure developed in Cd exposed rats was accompanied
with a significantly high urinary excretion of Cd2+, Zn2+ and proteins. The histopathology and electron microscopy of kidneys of Cd exposed rats documented changes of proximal tubular
degeneration. Notably, Cd content in renal cortex of Cd exposed rats was 215 μg/g tissue that was higher than the critical
concentration of Cd in kidneys which was associated with significantly higher Zn and metallothionein (MT) contents. Zinc uptake
in BLMVs isolated from kidneys of Cd exposed rats was significantly reduced. Further, kinetic studies revealed that decrease
in zinc uptake synchronized with decrease in maximal velocity (Vmax) and increase in affinity constant which is suggestive of decreased number of active zinc transporters. Furthermore, conformational
modulation of Zn transporter in BLM was further supported by observed variation in transition temperature for zinc transport
in BLMVs isolated from Cd-exposed kidney. 相似文献
14.
Stirpe A Rizzuti B Pantusa M Bartucci R Sportelli L Guzzi R 《European biophysics journal : EBJ》2008,37(8):1351-1360
There is growing evidence that metal ions can accelerate the aggregation process of several proteins. This process, associated
with several neuro-degenerative diseases, has been reported also for non-pathological proteins. In the present work, the effects
of copper and zinc ions on the denaturation and aggregation processes of β-lactoglobulin A (BLG-A) are investigated by differential
scanning calorimetry (DSC), fluorescence, electron paramagnetic resonance (EPR) and optical density. The DSC profiles reveal
that the thermal behaviour of BLG-A is a complex process, strongly dependent on the protein concentration. For concentrations
≤0.13 mM, the thermogram shows an endothermic peak at 84.3°C, corresponding to denaturation; for concentrations >0.13 mM an
exothermic peak also appears, above 90°C, related to the aggregation of the denaturated BLG-A molecules. The thioflavin T
fluorescence indicates that the thermally induced aggregates show fibrillar features. The presence of either equimolar Cu2+ or Zn2+ ions in the protein solution has different effects. In particular, copper binds to the protein in the native state, as evidenced
by EPR experiments, and destabilizes BLG-A by decreasing the denaturation temperature by about 10°C, whereas zinc ions probably
perturb the partially denaturated state of the protein. The kinetics of BLG-A aggregation shows that both metal ions abolish
the lag phase before the aggregation starts. Moreover, the rate of the process is 4.6-fold higher in the presence of copper,
whereas the effect of zinc is negligible. The increase of the aggregation rate, induced by copper, may be due to a site-specific
binding of the metal ion on the protein. 相似文献
15.
《Comparative biochemistry and physiology. A, Comparative physiology》1989,92(4):599-600
- 1.1. Freshwater-resident Arctic charr acclimated for 2 months at 8°C, 15% were divided into four experimental groups in July and exposed to 1 and 8°C in 15 and 34% salinity.
- 2.2. Only slight changes in gill Na-K-ATPase activity, blood plasma osmolality and blood plasma concentrations of Cl− and Mg2+ were found for the fish exposed to 1 or 8°C in brackish water.
- 3.3. When exposed to sea-water at 8°C, an increase in osmolality and in concentrations of Cl− and Mg2+ took place during the first 2–3 days, after which it levelled off.
- 4.4. If exposed to sea-water at 1°C, however, marked increases were found for all parameters measured and all the fish were dead within 5 days of exposure.
- 5.5. These results show that freshwater-resident Arctic charr—if acclimated to brackish water—can survive in sea-water during summer if the environmental temperature is not too low.
16.
It is estimated that nearly 50% of the world''s population is at risk of zinc (Zn) deficiency. The challenge is therefore to increase the Zn content in edible plant parts in order to improve the nutritional value of staple foods. We recently reported the identification and characterization of three barley genes encoding zinc transport proteins belonging to the ZIP protein family. These proteins are believed to be involved in cellular uptake of Zn2+. In this addendum, the Zn2+ transport capacity of ZIP proteins isolated from barley roots was investigated in response to various pH levels. We show that a lowering of pH induces a better growth at low Zn2+ concentrations of yeast cells expressing ZIP proteins. However, no significant change in transport capacity (Vmax) could be observed for HvIRT1, whereas lowering of pH from 5.5 to 4.2 increased the Vmax value with 64% for HvZIP5. These results indicate that proton activity has an important role in regulating the Zn2+ transport capacity of Zn2+ specific ZIP transport proteins. This information will increase the understanding of ZIP proteins and facilitate engineering of genotypes able to grow efficiently on marginal soils.Key words: ZIP proteins, barley, zinc transport, pH 相似文献
17.
D. Bordin L. Sartorelli G. Bonanni I. Mastrogiacomo E. Scalco 《Biological trace element research》1993,36(2):129-134
Physical exercise leads to many metabolic, cardiovascular, and muscular changes in the body. The trace elements (TE) zinc
and copper are directly involved, as enzymatic cofactors, in many of these processes, especially those related to nutrients
metabolism, oxygen transport, and formation of usable energy. The effects of high-intensity physical exercise on plasma levels
of CU2+ and Zn2+ in 19 subjects are investigated (9 males and 10 females). Plasma copper concentration decreases, and plasma zinc concentration
increases, after exercise, in both sexes. After 30 min recovery, both TE concentration values shifts-toward rest values in
both sexes.
These results only partially agree with literature data, probably because we used the treadmill exercise, which makes many
muscles work, whereas other authors made their subjects perform a cycloergometer exercise. Physical exercise causes a marked
redistribution of TE (copper and zinc) between body stores, bloodstream, and tissues. The condition of high metabolism may
lead to a deficiency of TE, requiring supplementation in order to maintain high level performance. 相似文献
18.
Tsunenobu Tamura Kelley E. Johnston Larry E. Freeberg Laura L. Perkins Robert L. Goldenberg 《Biological trace element research》1994,41(1-2):165-173
An evaluation of refrigeration (7°C) to prevent falsely high plasma or serum zinc concentrations owing to elapsed time between blood collection and centrifugation was performed. At room temperature (23°C), both plasma and serum zinc concentrations increased significantly, if blood samples were stored uncentrifuged. Plasma zinc concentrations increased 6.3% at 1 h and 40.7% at 24 h, whereas serum zinc concentrations increased only 0.9% at 1 h and 12.5% at 24 h at room temperature. When blood samples were stored uncentrifuged in the refrigerator for up to 24 h, there were no significant increases in zinc concentrations in either plasma or serum. These findings suggest that plasma or serum separation should be performed immediately after blood drawing to obtain accurate zinc concentrations, and if this is not feasible, the samples should be immediately refrigerated and separation performed within eight hours. 相似文献
19.
Giovanni B. Picotti Michele O. Carruba Carla Ravazzani Gian Pietro Bondiolotti Mosè Da Prada 《Life sciences》1982,31(19):2137-2143
Under basal conditions, the levels of circulating norepinephrine (NE) and epinephrine (E) were higher in normotensive Wistar rats of different origins than in Sprague-Dawley rats. Since the decline of 3H-NE concentration in the plasma after i.v. injection was similar in Wistar and in Sprague-Dawley rats, the higher levels of endogenous NE in the former strain probably reflect greater NE release from sympathetic nerve terminals. In normotensive Sprague-Dawley and Wistar rats, plasma NE rose to various extents during cold exposure (4°C), depending on the basal plasma NE levels. Compared with normotensive Wistar Kyoto rats (WKY), spontaneously hypertensive rats (SHR) had similar basal plasma E and NE concentrations, similar rates of 3H-NE disappearance, but more rapid increases to higher values of plasma NE during cold exposure. It is concluded that the basal rate of peripheral catecholamine release does not seem to be the main determining factor for arterial blood pressure in the various rat strains and that the sympathetic neuronal system of SHR is more responsive to cold exposure than that of WKY rats. 相似文献
20.
D. A. Gray S. K. Maloney 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1997,167(8):558-562
The relationship between body temperature (T
b) and the plasma concentrations of arginine vasotocin (AVT) and angiotensin II (AII) was examined in conscious, adult Pekin
ducks. Exposure of birds to an ambient temperature of 40 °C for 3 h increased T
b by about 1.5 °C and increased breathing rate five-fold. Plasma osmolality was elevated from the normothermic value of 294.9 ± 1.4
mosmol kg−1 by about 8 mosmol kg−1 Circulating AVT levels increased by about 2 pg ml−1 from a basal concentration of 4.98 ± 0.15 pg ml−1, a rise which could be accounted for by the change in osmotic status. Plasma AII concentrations were unchanged from the pre-heat
exposure value of 31.8 ± 3.4 pg ml−1. Time control birds, exposed only to an ambient temperature of 22 °C demonstrated no significant changes in any of the measured
variables. The results suggest that an increased T
b has no direct effect on the circulating concentrations of AVT or AII in ducks.
Accepted: 2 June 1997 相似文献