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1.
AbstractThe Maknassy basin is a typical example of an arid area in Central Tunisia. The geology of the area is mainly composed of Cretaceous calcareous formations. To identify the major process involved in controlling the groundwater chemistry, 53 groundwater samples for three different aquifer levels have been examined. The groundwater chemistry is dominated by SO 4 (Na + Mg) and (Cl + SO 4). The presence of (Ca + Mg) and (Na + K) with HCO 3 indicates the domination of dolomitic rock weathering as the major source of cations. The plots for Na to Cl indicate a fine correlation and reflects their release from halite dissolution during groundwater transition. An ion exchange process is also activated in study area which is indicated by a shift to the right in a plot for Ca + Mg to SO 4 + HCO 3. The plot of Na – Cl to Ca + Mg – (HCO 3 + SO 4) confirms that Ca, Mg and Na concentrations in groundwater are derived from aquifer materials. Saturation indexes of groundwater samples indicate undersaturation for gypsum and anhydrite, and oversaturation for calcite, dolomite and aragonite confirming waterrock interactions by dissolution and dilution processes. In general, water chemistry is guided by weathering process, ion exchange and water-rock interaction during groundwater transition. 相似文献
2.
Background and aimBee pollen is recognized to be a source of different nutrients, including minerals. As a food supplement, its quality and safety due to concentrations of essential macro- and microelements, and harmful trace elements has to be verified. Fast and simple element analysis of bee-collected pollen can be regarded as an important part of its quality assurance and control. The present study aimed at developping a new method for determination of selected elements (Ca, Cu, Fe, Mg, Mn, Zn) of bee pollen based on solvent extraction and completely avoiding a high temperature treatment with concentrated reagents. In addition, in vitro gastrointestinal digestion was used to assess bioavailability of elements from this food supplement. MethodsBee pollen samples were dried and pulverized. Total concentrations of Ca, Cu, Fe, Mg, Mn, and Zn were determined by flame atomic absorption spectrometry (FAAS) in sample solutions obtained by wet digestion (WD) in concentrated HNO 3 or alternatively by solvent extraction (SE) with diluted solutions of HNO 3. Gastrointestinal digestion was mimicked using simulated solutions of gastric and intestinal juices followed by determination of Ca, Cu, Fe, Mg, Mn and Zn concentrations in the bioaccessible fraction by FAAS. ResultsA new simple and fast method for determination of total concentrations of Ca, Cu, Fe, Mg, Mn, and Zn in bee pollen was developed and validated. The method combined room temperature, two-hour SE with 0.5 mol L −1 HNO 3 with FAAS measurements versus simple standard solutions. It provided precision within 1–5 % and trueness better than 8%, and was shown to be suitable for fast analysis of different polyfloral bee pollens. In vitro gastrointestinal digestion revealed that elements were well (70–85 % for Ca, Mg) and fairly (27–43 % for Cu, Fe, Mn, and Zn) bioaccessible from bee pollen. By pouring with water and swelling overnight, bioaccessibility of studied elements from such prepared bee pollen was increased on average by less than 15 % (Mn), 20 % (Ca, Cu, Fe, Zn) or 30 % (Mn). ConclusionsAvoiding long-lasting, high-temperature wet digestion with concentrated reagents, the proposed sample treatment along with FAAS provided precise and true results of total concentrations of Ca, Cu, Fe, Mg, Mn, and Zn in bee pollen. The method was simple and fast, and enabled to analyze a higher number of samples. Simulated gastrointestinal digestion of bee pollen have shown for the first time that Ca and Mg are the most bioaccessible from this bee product. Bioaccessibility of Cu, Fe, Mg, and Zn from bee pollen are close to or lower than 40 %. 相似文献
3.
Key messageOver-expression of CAX3 encoding a cation/proton exchanger enhances Cd tolerance by decreasing ROS (Reactive Oxygen Species) through activating anti-oxidative enzymes via elevation of Ca level in Arabidopsis AbstractCAXs (cation/proton exchangers) are involved in the sequestration of cations such as Mn, Li, and Cd, as well as Ca, from cytosol into the vacuole using proton gradients. In addition, it has been reported that CAX1, 2 and 4 are involved in Cd tolerance. Interestingly, it has been reported that CAX3 expressions were enhanced by Cd in Cd-tolerant transgenic plants expressing Hb1 (hemoglobin 1) or UBC1 (Ub-conjugating enzyme 1). Therefore, to investigate whether CAX3 plays a role in increasing Cd tolerance, CAX3 of Arabidopsis and tobacco were over-expressed in Arabidopsis thaliana. Compared to control plants, both transgenic plants displayed an increase in Cd tolerance, no change in Cd accumulation, and enhanced Ca levels. In support of these, AtCAX3-Arabidopsis showed no change in expressions of Cd transporters, but reduced expressions of Ca exporters and lower rate of Ca efflux. By contrast, atcax3 knockout Arabidopsis exhibited a reduced Cd tolerance, while the Cd level was not altered. The expression of Δ90-AtCAX3 (deletion of autoinhibitory domain) increased Cd and Ca tolerance in yeast, while AtCAX3 expression did not. Interestingly, less accumulation of ROS (H2O2 and O2?) was observed in CAX3-expressing transgenic plants and was accompanied with higher antioxidant enzyme activities (SOD, CAT, GR). Taken together, CAX3 over-expression may enhance Cd tolerance by decreasing Cd-induced ROS production by activating antioxidant enzymes and by intervening the positive feedback circuit between ROS generation and Cd-induced spikes of cytoplasmic Ca. 相似文献
4.
【目的】微生物诱导成矿是近年来地质微生物学领域研究中的热点之一。采用一株分离自喀斯特地区的岩生放线菌DHS C013^T菌株,研究该菌株及其代谢产物在由NaHCO3、Ca(NO3)2.4H2O组成的成矿体系中对CaCO3生成及形貌的影响。【方法】将在葡萄糖麦芽酵母提取物(MGYP)培养液中培养的放线菌上清液、菌丝球、发酵液以及无菌的MGYP培养液和超纯水分别加入成矿体系,SEM观察不同处理成矿体系中的底部沉淀物。【结果】在超纯水成矿体系中只形成标准菱面体方解石,而在添加放线菌及其代谢产物甚至含有机质的培养液则可形成形态各异的CaCO3晶体,如球形、哑铃以及表面具有鳞片状的柱形。这些特殊形态的CaCO3晶体的形成,可能是在放线菌的菌丝球和菌丝片段以及胞外分泌物上成核和逐渐生长的结果。【结论】放线菌菌丝体及代谢产物对调控和影响CaCO3的晶体形貌有重要作用。研究结果对进一步认识放线菌及其代谢产物诱导生物成矿提供了新的证据。 相似文献
5.
In rabbit atrial myocytes Ca signaling has unique features due to the lack of transverse (t) tubules, the spatial arrangement of mitochondria and the contribution of inositol-1,4,5-trisphosphate (IP 3) receptor-induced Ca release (IICR). During excitation-contraction coupling action potential-induced elevation of cytosolic [Ca] originates in the cell periphery from Ca released from the junctional sarcoplasmic reticulum (j-SR) and then propagates by Ca-induced Ca release from non-junctional (nj-) SR toward the cell center. The subsarcolemmal region between j-SR and the first array of nj-SR Ca release sites is devoid of mitochondria which results in a rapid propagation of activation through this domain, whereas the subsequent propagation through the nj-SR network occurs at a velocity typical for a propagating Ca wave. Inhibition of mitochondrial Ca uptake with the Ca uniporter blocker Ru360 accelerates propagation and increases the amplitude of Ca transients (CaTs) originating from nj-SR. Elevation of cytosolic IP 3 levels by rapid photolysis of caged IP 3 has profound effects on the magnitude of subcellular CaTs with increased Ca release from nj-SR and enhanced CaTs in the nuclear compartment. IP 3 uncaging restricted to the nucleus elicites ‘mini’-Ca waves that remain confined to this compartment. Elementary IICR events (Ca puffs) preferentially originate in the nucleus in close physical association with membrane structures of the nuclear envelope and the nucleoplasmic reticulum. The data suggest that in atrial myocytes the nucleus is an autonomous Ca signaling domain where Ca dynamics are primarily governed by IICR. 相似文献
6.
In rabbit atrial myocytes Ca signaling has unique features due to the lack of transverse (t) tubules, the spatial arrangement of mitochondria and the contribution of inositol-1,4,5-trisphosphate (IP 3) receptor-induced Ca release (IICR). During excitation-contraction coupling action potential-induced elevation of cytosolic [Ca] originates in the cell periphery from Ca released from the junctional sarcoplasmic reticulum (j-SR) and then propagates by Ca-induced Ca release from non-junctional (nj-) SR toward the cell center. The subsarcolemmal region between j-SR and the first array of nj-SR Ca release sites is devoid of mitochondria which results in a rapid propagation of activation through this domain, whereas the subsequent propagation through the nj-SR network occurs at a velocity typical for a propagating Ca wave. Inhibition of mitochondrial Ca uptake with the Ca uniporter blocker Ru360 accelerates propagation and increases the amplitude of Ca transients (CaTs) originating from nj-SR. Elevation of cytosolic IP 3 levels by rapid photolysis of caged IP 3 has profound effects on the magnitude of subcellular CaTs with increased Ca release from nj-SR and enhanced CaTs in the nuclear compartment. IP 3 uncaging restricted to the nucleus elicites ‘mini’-Ca waves that remain confined to this compartment. Elementary IICR events (Ca puffs) preferentially originate in the nucleus in close physical association with membrane structures of the nuclear envelope and the nucleoplasmic reticulum. The data suggest that in atrial myocytes the nucleus is an autonomous Ca signaling domain where Ca dynamics are primarily governed by IICR. 相似文献
7.
BackgroundDisorders of metal elements and platelet dysfunction are common in patients with trauma-induced coagulopathy (TIC). AimThe aim of this study was to explore the potential role of plasma metal elements in platelet dysfunction in TIC. MethodsThirty Sprague-Dawley rats were divided into control, hemorrhage shock (HS) and multiple injury (MI) groups. At timepoints of 0.5 and 3 h after trauma and being documented as HS 0.5 h, HS 3 h, MI 0.5 h or MI 3 h, blood samples were harvested for inductively coupled plasma mass spectrometer, conventional coagulation function and thromboelastograph. ResultsThe plasma zinc (Zn), vanadium (V) and cadmium (Ca) decreased initially in HS 0.5 h and recovered slightly in HS 3 h, whereas their plasma concentrations continued to decrease from beginning till MI 3 h ( p < 0.05). In HS, plasma Ca, V and nickel were negatively correlated to the time taken to reach the initial formation (R), whereas R was positively correlated to plasms Zn, V, Ca and selenium in MI ( p < 0.05). In MI, plasma Ca was positively correlated to maximum amplitude, and plasma V was positively correlated to platelet count ( p < 0.05). ConclusionThe plasma concentrations of Zn, V and Ca appeared to contribute to platelet dysfunction in HS 0.5 h, HS 3 h, MI 0.5 h and MI 3 h, which were trauma type sensitive. 相似文献
8.
BackgroundAquaporin-8 (AQP8), a member of the aquaporin water channel family, is expressed in various tissue and cells, including liver, testis, and pancreas. AQP8 appears to have functions on the plasma membrane and/or on the mitochondrial inner membrane. Mitochondrial AQP8 with permeability for water, H 2O 2 and NH 3 has been expected to have important role in various cells, but its information is limited to a few tissues and cells including liver and kidney. In the present study, we found that AQP8 was expressed in the mitochondria in mouse adipose tissues and 3T3-L1 preadipocytes, and investigated its role by suppressing its gene expression. MethodsAQP8-knocked down (shAQP8) cells were established using a vector expressing short hairpin RNA. Cellular localization of AQP8 was examined by western blotting and immunocytochemistry. Mitochondrial function was assessed by measuring mitochondrial membrane potential, oxygen consumption and ATP level measurements. ResultsIn 3T3-L1 cells, AQP8 was expressed in the mitochondria. In shAQP8 cells, mRNA and protein levels of AQP8 were decreased by about 75%. The shAQP8 showed reduced activities of complex IV and ATP synthase; it is probable that the impaired mitochondrial water handling in shAQP8 caused suppression of the electron transport and ADP phosphorylation through inhibition of the two steps which yield water. The reduced activities of the last two steps of oxidative phosphorylation in shAQP8 cause low routine and maximum capacity of respiration and mitochondrial hyperpolarization. ConclusionMitochondrial AQP8 contributes to mitochondrial respiratory function probably through maintenance of water homeostasis. General significanceThe AQP8-knocked down cells we established provides a model system for the studies on the relationships between water homeostasis and mitochondrial function. 相似文献
9.
BackgroundCadmium (Cd) is a major environmental pollutant and chronic toxicity could induce nephropathy by increasing renal oxidative stress and inflammation. Although vitamin D (VD) and calcium (Ca) prophylactic treatments attenuated Cd-induced cell injury, none of the prior studies measure their renoprotective effects against pre-established Cd-nephropathy. AimsTo measure the alleviating effects of VD and/or Ca single and dual therapies against pre-established nephrotoxicity induced by chronic Cd toxicity prior to treatment initiation. MethodsForty male adult rats were allocated into: negative controls (NC), positive controls (PC), Ca, VD and VC groups. The study lasted for eight weeks and all animals, except the NC, received CdCl 2 in drinking water (44 mg/L) throughout the study. Ca (100 mg/kg) and/or VD (350 IU/kg) were given (five times/week) during the last four weeks to the designated groups. Subsequently, the expression of transforming growth factor-β (TGF-β1), inducible nitric oxide synthase (iNOS), neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), VD synthesising (Cyp27b1) and catabolizing (Cyp24a1) enzymes with VD receptor (VDR) and binding protein (VDBP) was measured in renal tissues. Similarly, renal expression of Ca voltage-dependent channels (Ca V1.1/Ca V3.1), store-operated channels (RyR1/ITPR1), and binding proteins (CAM/CAMKIIA/S100A1/S100B) were measured. Serum markers of renal function alongside several markers of oxidative stress (MDA/H 2O 2/GSH/GPx/CAT) and inflammation (IL-6/TNF-α/IL-10) together with renal cell apoptosis and expression of caspase-3 were also measured. ResultsThe PC group exhibited hypovitaminosis D, hypocalcaemia, hypercalciuria, proteinuria, reduced creatinine clearance, and increased renal apoptosis/necrosis with higher caspase-3 expression. Markers of renal tissue damage (TGF-β1/iNOS/NGAL/KIM-1), oxidative stress (MDA/H 2O 2), and inflammation (TNF-α/IL-1β/IL-6) increased, whilst the antioxidants (GSH/GPx/CAT) and IL-10 decreased, in the PC group. The PC renal tissues also showed abnormal expression of Cyp27b1, Cyp24a1, VDR, and VDBP, alongside Ca-membranous (Ca V1.1/Ca V3.1) and store-operated channels (RyR1/ITPR1) and cytosolic Ca-binding proteins (CAM/CAMKIIA/S100A1/S100B). Although VD was superior to Ca monotherapy, their combination revealed the best mitigation effects by attenuating serum and renal tissue Cd concentrations, inflammation and oxidative stress, alongside modulating the expression of VD/Ca-molecules. ConclusionsThis study is the first to show improved alleviations against Cd-nephropathy by co-supplementing VD and Ca, possibly by better regulation of Ca-dependent anti-oxidative and anti-inflammatory actions. 相似文献
11.
Alkaline-earth metal complexes of the monoanionic form of the polyether ionophore monensin A were isolated for the first time
in solid state and were structurally characterized using various spectroscopic methods (IR, NMR, FAB-MS). The stoichiometric
reaction of monensic acid (MonH) with M 2+ (M = Mg, Ca) in the presence of an organic base leads to the formation of mononuclear complexes of composition [M(Mon) 2(H 2O) 2]. The structures of magnesium ( 1) and calcium ( 2) monensin complexes in the solid state were established by single crystal X-ray crystallography. The complexes crystallize
as [Mg(Mon) 2(H 2O) 2]·5MeCN ( 1) and [Ca(Mon) 2(H 2O) 2]·H 2O·5MeCN ( 2) in the monoclinic P21 space group. The alkaline-earth metal ion is placed in a distorted octahedral environment, defined by two monensin anions
acting as bidentate ligands in the equatorial plane of the complex as well as by two water molecules occupying the axial positions
of the inner coordination sphere. The bactericidal activity of 1 and 2 was evaluated against aerobic Gram-positive microorganisms applying the double layer agar hole diffusion method. 相似文献
12.
Possible involvement of calcium (Ca) and zinc (Zn) in mitigation of salt (NaCl) stress-induced oxidative damage in Brassica juncea was investigated. Salt stress (200?mM NaCl) reduced leaf pigment synthesis and some key photosynthetic attributes including stomatal conductance and internal CO 2 concentration. Exogenous application of Ca and Zn resulted in enhanced growth possibly by induction of the antioxidant defense system, resulting in improved redox state thereby favoring growth improvement. Proline accumulation (3.39-fold) was stimulated by exogenous application of Zn and Ca causing improvement in growth through enhancement in relative water content (78.46%) and increased flavonoid accumulation (86.19%). NaCl stress enhanced the hydrogen peroxide (H 2O 2), malondialdehyde and methylglyoxal content by 3-fold, 1.51-fold, and 2.98-fold, respectively, however, supplementation of Ca and Zn individually as well as in combination reduced the accumulation to an appreciable level. Ca and Zn treatment helped Brassica juncea plants to strengthen the antioxidant system and glyoxalase system and also enzymes of ascorbate-glutathione (AsA-Glu) cycle for better protection to membranes from reactive oxygen species. Moreover, Ca and Zn supplementation reduced the salt-induced damage by maintaining Na/K ratio through improved K uptake. 相似文献
13.
The flowering of Lemna perpusilla strain 6746 is inhibited by daily transfers to water for short periods during a sensitive phase. Supplementing the water with Ca(NO 3) 2 partially reverses the inhibition of flowering while MgSO 4 increases the inhibition. The inhibition by MgSO 4 is overcome by low concentrations of Ca(NO 3) 2. Flower-promoting activity was detected in water and in MgSO 4 solutions that had been incubated with plants under dark but not light conditions. The prevention of this effect by light appears to be photosynthetic rather than to depend on phytochrome. The activity is destroyed by autoclaving but not by brief boiling. This loss of a flower-promoting material may explain the inhibiting effect on flowering by transfers to water. 相似文献
14.
AimsHigh pH, and high bicarbonate (HCO3−) and calcium (Ca) availability characterise calcareous soils. High [Ca] only partially explains why some Lupinus species are calcifuge, so we explored high [HCO3−] and high pH. MethodsWe grew six Lupinus genotypes in hydroponics with pH 5, 6.5 and 8a (adjusted by KOH), and 8b (adjusted by KHCO3). Leaf symptoms and areas, root appearance and biomass were recorded; whole leaf and root nutrient concentrations, and leaf cellular phosphorus (P), Ca and potassium (K) concentrations were determined using elemental X-ray microanalysis. ResultsChlorosis was observed in young leaves at high pH for L. angustifolius and L. cosentinii, and P deficiency at high pH for all genotypes. High pH decreased iron (Fe) and zinc (Zn) uptake in all genotypes. It also decreased lateral root growth, the uptake of P, K, Ca, and manganese (Mn) by all sensitive species; and translocation of P, Fe, Zn, Mn, and Ca to leaves in most sensitive species. However, leaf [Ca], leaf [K], [K] within each measured cell type, and translocation of K and Ca to leaves of L. pilosus and L. cosentinii at pH 8 were greater than at pH 5 and 6.5. Compared with pH 8a, all L. angustifolius genotypes translocated more P, Fe, Zn, Mn and K from roots to leaves at pH 8b. High pH did not affect the leaf cell types that accumulated P and Ca, but decreased the leaf cellular [P]. ConclusionsLupinus angustifolius and L. cosentinii were sensitive to high [HCO3−] and/or high pH; L. pilosus was relatively tolerant. High pH decreased lateral root growth and nutrient uptake, inhibiting growth of sensitive species. High [HCO3−] diminished the negative effect of pH 8 on nutrient translocation to leaves in most L. angustifolius genotypes. This knowledge provides critical insights into the habits of Lupinus species to guide breeding of calcicole plants. 相似文献
15.
Summary Cotton seedlings were germinated in either tap water or a CaSO 4 solution and then grown for two days in nutrient solutions containing 0.1, 1.0, or 10.0 me Ca/1. They were then transferred
to cultures having the same Ca variables and the roots subjected to temperatures of 26, 18, 15 and 12°C for four days. The
fresh weight of all plant parts and leaf area increased with increasing root temperatures and with increasing Ca levels, the
effect of Ca being most pronounced at the higher temperatures. The dry weight was increased by increasing root temperature;
the effect of Ca was rather small. Water use increased with increasing temperature and was higher for the lowest Ca level
than for the higher levels. The results emphasize the overriding effect of low temperature on water uptake. Calcium had little
effect on the growth depression resulting from low root temperatures.
Joint contribution from the Agronomy Department, Mississippi Agricultural Experiment Station, State College and the Soil Science
Department, North Carolina Agricultural Experiment Station, Raleigh. Published with the approval of the Directors of Research
as Journal Contribution No. 1530 and Paper No. 2389 of the Journal Series, respectively. This is a report of research conducted while the author was on sabbatical leave at North
Carolina State University, February 1–September 10, 1965. 相似文献
16.
【背景】嗜热古菌Candidatus Syntrophoarchaeum可以与硫酸盐还原细菌共生,通过逆转产甲烷途径进行正丁烷的氧化,但在该过程中负责催化丁基辅酶M氧化的酶尚未确定。【目的】利用分子动力学模拟证明Ca.Syntrophoarchaeum中mta A基因编码的蛋白可以特异性催化丁基辅酶M中丁基的转移,并非转移甲基。【方法】使用Methanosarcina mazei辅酶M甲基转移酶Mta A的晶体结构(PDB ID:4ay8)作为模板,对Mta A_1 (Gen Bank登录号OFV65993.1)和Mta A_2 (Gen Bank登录号OFV65678.1)进行同源建模。使用分子对接得到两者分别结合CH_3-Co M和C_4H_9-Co M时的结构,并用AMBER18进行分子动力学模拟。【结果】当Mta A_1和Mta A_2分别结合C_4H_9-Co M时,表现出与4ay8晶体结构类似的TIM-Barrel折叠三维结构,但在活性中心形状、Zn~(2+)与底物距离以及活性位点附近氨基酸配位方式等方面存在差异,这可能是导致Ca.Syntrophoarchaeum中mta A基因编码的蛋白催化丁基辅酶M氧化的原因。其中Mta A_2与4ay8结构更相似,活性中心氨基酸配位更完整,暗示其更可能具备催化活性。然而当Mta A_1和Mta A_2分别结合CH_3-Co M时,整体结构不合实际,活性中心Zn~(2+)与底物距离过远,表明底物几乎不可能与酶结合。【结论】Ca.Syntrophoarchaeum中的Mta A_1和Mta A_2很可能是特异性的丁基转移酶,而非催化甲基的转移,其中Mta A_2具备活性的可能性更高。 相似文献
17.
Brassinosteroids (BRs) can effectively alleviate the oxidative stress caused by Ca(NO 3) 2 in cucumber seedlings. The root system is an essential organ in plants due to its roles in physical anchorage, water and nutrient uptake, and metabolite synthesis and storage. In this study, 24-epibrassinolide (EBL) was applied to the cucumber seedling roots under Ca(NO 3) 2 stress, and the resulting chemical and anatomical changes were characterized to investigate the roles of BRs in alleviating salinity stress. Ca(NO 3) 2 alone significantly induced changes in the components of cell wall, anatomical structure, and expression profiles of several lignin biosynthetic genes. Salt stress damaged several metabolic pathways, leading to cell wall reassemble. However, EBL promoted cell expansion and maintained optimum length of root system, alleviating the oxidative stress caused by Ca(NO 3) 2. The continuous transduction of EBL signal thickened the secondary cell wall of casparian band cells, thus resisting against ion toxicity and maintaining water transport. 相似文献
18.
This study assessed the responses of vitamin-D 3 intraperitoneally injected to Rohu, Labeo rohita @ of 0 IU/kg bw (only solvent), 100 IU/kg bw and 500 IU/kg bw reared in 20 and 40 ppm of calcium (Ca) enriched water. The cellular changes in Corpuscles of Stannius (CS) gland, serum Ca, and inorganic phosphate (P i) level were analysed up to the 60th day. Rohu administered with 100 IU/kg bw D 3 and exposed to 40 ppm Ca-rich water exhibited notable hyperplasia of CS compared with their control groups. Notable changes with high serum Ca level (13.87 ± 0.3 mg/dl) was detected on the 5th day in fish exposed to 40 ppm Ca-rich water, while related values attained (13.74 ± 0.1 mg/dl) only after 7 days in 20 ppm Ca-rich water of 500 IU/kg bw vitamin D 3 injection. Similarly, high serum P i level (7.66 ± 0.2 mg/dl) in 40 ppm Ca injected with D 3 at 500 IU/kg bw. The results demonstrated that the Ca homeostasis of Labeo rohita is influenced by intra-peritoneal vitamin D 3. Progressive studies should be conducted by increasing the dose of vitamin D 3 to investigate optimum dose/supplement in feed for commercially important aquaculture teleost Labeo rohita for maximum and sustainable absorption of Ca from the variable water Calcium levels to maintain Ca 2+ homeostasis. 相似文献
19.
We investigated how the K/Ca, Na/Ca, Mg/Ca, and Sr/Ca ratios of powders ground from Porites coral skeletons are changed by cumulative chemical treatments to the powders: first with distilled/deionized water (DDW), next with 30?% H 2O 2 and then with 0.004?mol?l ?1 HNO 3. The K/Ca, Na/Ca, and Mg/Ca ratios were decreased with the DDW treatment and then increased with the H 2O 2 and HNO 3 treatments; the Sr/Ca ratio was slightly decreased through the cumulative treatments, suggesting fine-scale (tens of ??m or less) elemental heterogeneities in the skeleton??K, Na, and Mg are significantly enriched at the skeletal surface and also at the center of calcification (COC); in contrast, the heterogeneity of Sr is very small. We suggest that the principal mechanisms of K incorporation into coral skeleton are (1) ion incorporation into lattice defects/distortions and (2) ion adsorption onto crystal discontinuities (including crystal?Corganic matter interfaces) as forms of K + and KSO 4 ?. Furthermore, we measured the element/Ca ratios of a modern Porites coral skeleton along its growth direction at 2-mm intervals. Results showed that all the element/Ca ratios displayed annual cycles, that the K/Ca and Na/Ca ratios covaried with each other, and that the annual-minimum K/Ca and Na/Ca ratios coincided with the annual high-density band in the skeleton. It is unclear what environmental factors may cause the covarying annual cycles of the K/Ca and Na/Ca ratios; however, as a possible explanation, the cycles may be due not to environmental factors, but to a combined effect of (1) the K and Na enrichment at the COC, (2) annual bands of high- and low-density skeleton, and (3) mm-scale element/Ca measurements along the skeletal growth direction. This kind of effect on geochemical proxies of which the concentrations significantly differ between the COC and surrounding skeleton may generate false or distorted paleoenvironmental signals. 相似文献
20.
SUMMARYIn order to elucidate the preventive mechanism of molybdenum (Mo) against carcinogenesis of N-nitroso compounds, the effects of in vivo Mo-pretreatment on N-nitrosodiethylamine (NDEA)-induced hepatotoxicity in rats were examined. Effects of in vitro Mo-pretreatment on NDEA-induced DNA strand breaks and fluctuation of the cytosolic free Ca levels in rat hepatocytes were also investigated. Male Wistar rats weighing 170–190 g were pretreated with 10 ppm Mo as Na 2MoO 4 in deionized drinking water for 21 days, and on day 22, they were exposed to NDEA (50 mg/kg body weight, once, i.p.). 3 and 5 days after NDEA exposure, serum lactic dehydrogenase (LDH) activity, and hepatic calcium (Ca) content and lipid peroxidation levels were evaluated. In vivo Mo-pretreatment prevented NDEA-induced elevations in serum LDH activity and liver Ca content but increased hepatic lipid peroxidation levels. Hepatocytes isolated from rats pretreated with sodium phenobarbital (80 mg/kg body weight, i.p., once a day for 3 days) were exposed to NDEA (0, 100, 250 and 500 μM) in vitro for 30 min at 37°C. NDEA treatment caused DNA strand breaks and a perturbation of cytosolic free Ca level. However, in vitro Mo-pretreatment (20 μM, 20 min at 37°C) suppressed the NDEA-induced DNA damage and disruption of intracellular Ca homeostasis. These results suggest Mo protected against NDEA-induced hepatotoxicity by stimulating the metabolism of the nitroso compound via a nontoxic pathway (denitration) while preventing DNA damage connected with alteration in cytosolic free Ca levels. Thus, the general protective action of Mo against N-nitroso compound-induced carcinogenesis may be explained by a common mechanism. 相似文献
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