Hypophosphatemia Induced by Dietary Aluminium Hydroxide Supplementation in Growing Pigs: Effects on Erythrocytes,Myocardium, Skeletal Muscle and Liver

Three groups of pigs were studied during and after 10 weeks of treatment with either Al(OH)3 (Al[OH]3-group, n=8) to induce hypophosphatemia, A1P04 (AlP04-group, n=8, aluminium control without hypophosphatemia) or no addition to the feed (control group, n=8). Blood samples were taken at the start of the experiment and after 3, 6 and 10 weeks and were analyzed for phosphate, calcium and 2,3-diphosphoglycerate (2,3-DPG). Samples from myocardium, skeletal muscle and liver were obtained in connection with exsanguination and analyzed for glycogen, adenosine-tri-phosphate (ATP), creatine phosphate (CP), glucose-6-phosphate (G-6-P) and lactate. The Al(OH)3-group became hypophosphatemic and hypercalcémie with low levels of 2,3-DPG in erythrocytes within 3 weeks and showed a retarded growth rate. After 10 weeks the Al(OH)3-group had low levels of ATP in myocardium as compared with the control-group and low levels of G-6-P as compared with the AlP04-group. No disturbances on electro-cardiograms registered at rest could be documented. G-6-P concentration was low in the biceps muscle in the Al(OH)3-group as compared with the AlP04-group and in the liver low G-6-P concentration was seen in addition to high lactate concentration. The fibre type composition in M. Longissimus did not differ between groups, but the Al(OH)3-group had, due to retardation in growth, smaller mean fibre-areas than pigs in the AlP04-group. Hypophosphatemia gave rise to high serum calcium levels, low concentration of 2,3-DPG in erythrocytes and influenced G-6-P concentration in skeletal muscle, G-6-P and ATP in myocardium, G-6-P and lactate in liver. Retarded growth was one serious consequence of hypophosphatemia and the disturbed energy metabolism.     

Aluminium speciation in the Vienne river on its upstream catchment (Limousin region, France)

The aim of this study was to investigate the speciation of aluminium in the river Vienne on its upstream catchment (Limousin region, France) over a period of seven years (May 1998-September 2004) in order to assess harmful effects on aquatic life. Two sampling points were selected: the first at 4 km from the spring (Peyrelevade), and the second one at 89 km from the spring (Royères). The aluminium speciation was computed with Mineql+ 4.5 speciation software. Organic matter and phosphorous play a major role in aluminium speciation. If we consider the free aluminium ion (Al3+) as being the only toxic form of aluminium, the concentrations of toxic forms recorded at Peyrelevade and Royères were always below the toxic values for fish. However, if the sum of the concentrations of Al3+, Al(OH)2+, Al(OH)2+ and Al(OH)4- is taken into consideration, the concentration of aluminium recorded may have adverse effects on aquatic life in the upstream catchment of the river Vienne. Al(OH)4- is the major contributor to the concentration in toxic aluminium recorded. In general, Al(OH)4- forms appears in water during the summer with water alkalinisation due to an increase in photosynthetic activities.     

Triticum aestivum shows a greater biomass response to a supply of aluminium phosphate than Lupinus albus, despite releasing fewer carboxylates into the rhizosphere

The relationship between carboxylate release and the ability of plants to access phosphorus from AlPO4 and to detoxify aluminium was studied by comparing species with a low and high rate of carboxylate release, Triticum aestivum (wheat) and Lupinus albus (white lupin), respectively. Species were supplied with P at 10, 20, 40 or 100 mg P kg-1 sand in the form of sparingly soluble AlPO4 or soluble KH2PO4; control plants did not receive any P. Triticum aestivum was significantly better than L. albus at accessing P from AlPO4, despite accumulating fewer carboxylates in its rhizosphere. Rhizosphere pH of L. albus did not vary with form or level of P supply, while the rhizosphere pH of T. aestivum increased with the level of P supplied. Based on the evidence in the present study, a model is proposed to explain the poor performance of L. albus, whereby the release of carboxylates and associated protons reduces the chelating ability of exuded carboxylates, thus reducing P acquisition and increasing Al toxicity.     

The abnormal phenotypes of cartilage and bone in calcium-sensing receptor deficient mice are dependent on the actions of calcium, phosphorus, and PTH

Patients with neonatal severe hyperparathyroidism (NSHPT) are homozygous for the calcium-sensing receptor (CaR) mutation and have very high circulating PTH, abundant parathyroid hyperplasia, and severe life-threatening hypercalcemia. Mice with homozygous deletion of CaR mimic the syndrome of NSHPT. To determine effects of CaR deficiency on skeletal development and interactions between CaR and 1,25(OH)(2)D(3) or PTH on calcium and skeletal homeostasis, we compared the skeletal phenotypes of homozygous CaR-deficient (CaR(-/-)) mice to those of double homozygous CaR- and 1α(OH)ase-deficient [CaR(-/-)1α(OH)ase(-/-)] mice or those of double homozygous CaR- and PTH-deficient [CaR(-/-)PTH(-/-)] mice at 2 weeks of age. Compared to wild-type littermates, CaR(-/-) mice had hypercalcemia, hypophosphatemia, hyperparathyroidism, and severe skeletal growth retardation. Chondrocyte proliferation and PTHrP expression in growth plates were reduced significantly, whereas trabecular volume, osteoblast number, osteocalcin-positive areas, expression of the ALP, type I collagen, osteocalcin genes, and serum ALP levels were increased significantly. Deletion of 1α(OH)ase in CaR(-/-) mice resulted in a longer lifespan, normocalcemia, lower serum phosphorus, greater elevation in PTH, slight improvement in skeletal growth with increased chondrocyte proliferation and PTHrP expression, and further increases in indices of osteoblastic bone formation. Deletion of PTH in CaR(-/-) mice resulted in rescue of early lethality, normocalcemia, increased serum phosphorus, undetectable serum PTH, normalization in skeletal growth with normal chondrocyte proliferation and enhanced PTHrP expression, and dramatic decreases in indices of osteoblastic bone formation. Our results indicate that reductions in hypercalcemia play a critical role in preventing the early lethality of CaR(-/-) mice and that defects in endochondral bone formation in CaR(-/-) mice result from effects of the marked elevation in serum calcium concentration and the decreases in serum phosphorus concentration and skeletal PTHrP levels, whereas the increased osteoblastic bone formation results from direct effects of PTH.     

Characterisation of Ca- and Al-pectate gels by thermal analysis and FT-IR spectroscopy

Thermal analysis (TG-DTA) and FT-IR spectroscopy have been performed on calcium-pectate membranes to investigate their structure and the consequent variation caused by aluminium sorption. Calcium-polygalacturonate (Ca-PG) membranes, model systems of the soil-root interface, were exposed to aluminium solutions at different concentrations (25-800 microM). Three different pHs (3.50, 4.00 and 4.50) were chosen to study the influence of different aluminium species, such as [Al(H2O)6]3+, [Al(OH)(H2O)5]2+ and [Al(OH)2(H2O)(4)]+, on the structure of the Ca-PG membrane. The DTA profiles and FT-IR spectra showed how aluminium sorption induces structural modifications leading to a reorganisation of the chain aggregates and a weakening of the structure. Higher pH, that is, 4.00 and 4.50, and thus hydrolytic aluminium species and related higher calcium content maintain a more regular structure than at pH 3.50. At pH 3.50, both the effect of [Al(H2O)6]3+ and a major calcium release had a greater impact and thus induced a greater weakening of the structure.     

Long-term treatment of postmenopausal osteoporosis with active vitamin D3, 1-alpha-hydroxycholecalciferol (1 alpha-OHD3) and 1, 24 Dihydroxycholecalciferol (1, 24(OH)2D3)

The effects of active vitamin D3 analogues on radial mineral content (RMC) in postmenopausal osteoporosis were examined. Seventy eight subjects with postmenopausal osteoporosis were divided into 5 groups; Group 1 (n = 23) as the control group and Group 2 (n = 27), Group 3 (n = 8), Group 4 (n = 9) and Group 5 (n = 11) which were given 1 microgram of 1, 24(R) (OH)2D3 per day, 1 microgram of 1, 24(S)(OH)2D3 per day, 0.5 and 1 microgram of 1 alpha-OHD3 per day for 6 to 24 months, respectively. After 3-months administration of these drugs, RMC values were significantly increased in Groups 2 (102.8 +/- 1.8%), 4 (103.9 +/- 3.3%) and 5 (114.2 +/- 3.6%), when compared with the controls (97.9 +/- 2.4%). RMC in Group 3 (97.9 +/- 2.4%) was not significantly different from the control value. The administration of 1 alpha-OHD3 caused in increase in RMC in a dose-related manner. A rapid decrease in RMC was observed after withdrawal of the treatment in Groups 2, 4, and 5. A subsequent increase in RMC was observed after re-administration of 1 alpha-OHD3 and 1, 24(R)(OH)2D3. Serum Ca levels were increased in the group treated with 1, 24(R)(OH)2D3 and were decreased after the discontinuation of 1 alpha-OHD3 administration. Serum A1-P activity was decreased by treatment with 1 alpha-OHD3 (1 microgram per day) and a subsequent increase was observed in both groups treated with 1, 24(R)(OH)2D3 and 1 alpha-OHD3. Serum PTH levels were decreased by the administration of 1, 24(R)(OH)2D3 and 1 alpha-OHD3. In the group treated with 1 microgram of 1 alpha-OHD3 per day, hypercalcemia (2 out of 11 cases and these patients took calcium tablets) and an increase in BUN (1 out of 2 hypercalcemic patients) were observed.(ABSTRACT TRUNCATED AT 250 WORDS)     

Combined supplementation of vanadium and 1alpha,25-dihydroxyvitamin D(3) inhibit diethylnitrosamine-induced rat liver carcinogenesis

A combination of a differentiation-inducing agent like 1alpha, 25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] with a compound that blocks entry of calcium into cells like vanadium (V) may offer a new approach to differentiation therapy and address the problem of hypercalcemia. Initiation of hepatocarcinogenesis was performed by a single intraperitoneal injection of diethylnitrosamine (DEN) (200 mg/kg b.wt.) in male Sprague-Dawley rats. Supplementation of V, 1, 25(OH)(2)D(3), or both V and 1,25(OH)(2)D(3) were started 4 weeks prior to DEN injection and continued thereafter till 20th week. It was observed that supplementation of V (0.5 ppm) in drinking water ad libitum or 1,25(OH)(2)D(3) (3 microg/ml propylene glycol) per os twice weekly for the entire period of the experiment significantly reduces the number and size of hyperplastic nodules while the combination treatment offered an additive effect in reducing it to 37.5% from 83.3%. V-1,25(OH)(2)D(3) combination was also effective in elevating the level of hepatic microsomal cytochrome P-450 (Cyt. P-450) (P<0.001). Moreover, A significant reduced level of cytosolic glutathione (GSH) (P<0.001) and glutathione S-transferase (GST) (P<0.001) activity as well as reduction in the appearance of gamma-glutamyltranspeptidase (GGT)-positive foci (P<0.001) as compared to carcinogen control were observed in V plus 1, 25(OH)(2)D(3) treated group. These results suggest that V may be useful in combination with 1,25(OH)(2)D(3) in the inhibition of experimental rat hepatocarcinogenesis.     

Pea roots affect immobilisation and solubilisation of phosphorus depending on genotype, stage and phosphorous source

To assess the efficiency of pea roots to mobilize available phosphorus (P) from P compounds we subjected various pea genotypes to a post-treatment method. Axenic seedlings were raised on P-deficient semisolid synthetic medium using control blanks without a plant otherwise treated in the same way. AlPO(4), CaHPO(4), FePO(4), apatite and meat-bone-meal (MBM) were tested. A genotype was tested from 1-day through 15-days of growth. There were differences between the compounds (p < 0.001). P was dissolved from CaHPO(4) with apparent maxima at 72-h intervals and to a significantly lesser extent from MBM. With AlPO(4), FePO(4) and apatite, the roots did not show a dissolving effect, but, on the contrary, significantly immobilised P. In each case a correlation with an increase in acidity, H(+) (p < 0.001) was observed. The correlation was negative in the AlPO(4), FePO(4) and apatite series. A CaHPO(4) treatment combined with apatite or MBM significantly decreased solubility of P from that of CaHPO(4) singly. Tests with six additional genotypes showed that all solubilised P from CaHPO(4), some to a significant extent from apatite, MBM or slightly from FePO(4), but none from AlPO(4). The accumulation of nearly water-insoluble aluminium and iron phosphates in field and virgin soils is partly explainable by the immobilisation through the root action on P, which we have found also with other plant species. The root responses must also have ecophysiological functions distinct from P acquisition.     

Intraportal autotransplantation of cryopreserved porcine islets of Langerhans

Mechanically prepared isolated islets of Langerhans were cryopreserved in liquid nitrogen for a period of 4 days. Intraportal autotransplantation studies were performed on two groups of six pigs rendered diabetic by total pancreatectomy (group 2) or by partial pancreatectomy combined with streptozotocin (group 4) and compared with two control groups (groups 1 and 3, respectively). The pigs were assessed for survival, weight gain, glycosuria, polyuria, systemic blood sugar and insulin, and, in selected pigs, intravenous glucose tolerance tests. Results showed that partial pancreatectomy with streptozotocin was the better tolerated experimental diabetes. Variable control of hyperglycemia was obtained over an experimental period of 3 months. Random blood glucose returned to normal in one of six pigs in the totally pancreatectomized group and three of six pigs in the partial pancreatectomy and streptozotocin group. Despite these normal circulating glucose levels, imperfect glucose homeostasis was achieved as shown by the response to glucose tolerance testing. These results report blood glucose control after cryopreserved islet autotransplants in diabetic pigs but further study is still necessary to achieve consistency.     

The effect of aluminium in Atlantic salmon (Salmo salar) with special emphasis on alkaline water

Atlantic salmon (Salmo salar) parr were exposed to aluminium under both steady state and non-steady state chemical conditions in alkaline water. Under alkaline (pH 9.5) steady state conditions, approximately 350 microg Al l(-1) (predominantly aluminate, Al(OH)(4)(-)) had no acute toxic effect on the salmon. The fish, however, showed a physiological response after 3 weeks of exposure ( approximately 300% increase in blood glucose concentration, about 30% increase in blood haematocrit, and about 15% decrease in plasma Cl(-) concentration). No increase in toxicity was evident under non-steady state conditions, i.e. lowering Al solubility as pH was lowered from 9.5 to 7.5. The results indicate that the toxicity of the aluminate ion (Al(OH)(4)(-)) is low, and particularly lower than the corresponding toxicity of cationic Al hydroxides. The effects observed in fish exposed to Al-rich water at pH 9.5 were counteracted as Al solubility was decreased by lowering pH to 7.5. This is contrary to previous observations where Al solubility has been lowered by increasing pH from 5.0 to 6.5.     

Silicic acid (Si(OH)(4)) is a significant influence upon the atomic absorption signal of aluminium measured by graphite furnace atomic absorption spectrometry (GFAAS).

We have identified silicic acid (Si(OH)(4)) as an important modifier of the absorbance signal of aluminium measured by graphite furnace atomic absorption spectrometry (GFAAS). The presence of Si(OH)(4) enhanced the signal by as much as 50%. The extent of the enhancement was dependent upon both [Al] and [Si(OH)(4)] and was maximal when [Al]< or =4.44 micromol dm(-3) and [Si(OH)(4)]> or =0.50 mmol dm(-3). The enhancement of the Al absorbance signal was not linearly related to [Si(OH)(4)] and the effect was, generally, saturated, for all [Al] tested, at [Si(OH)(4)]> or =0.50 mmol dm(-3). Si(OH)(4) was significantly more effective in enhancing the Al absorbance signal than Mg(NO(3))(2). However, the co-occurrence of 10 mmol dm(-3) Mg(NO(3))(2) and 2 mmol dm(-3) Si(OH)(4) in samples abolished the enhancement due to Si(OH)(4). The presence of Si(OH)(4) in samples could result in an overestimation of the Al content of those samples by as much as 50%. Errors in the measurement of Al in samples containing Si(OH)(4) could be prevented using matrix-matched calibration standards. Our observation could have serious implications for the determination of Al in aqueous samples of both geochemical and biological interest. It may also point towards the application of Si(OH)(4) as a novel and effective matrix modifier in the determination of Al by GFAAS since the inclusion of Si(OH)(4) in standards and samples improved the limit of detection of Al from ca 8 nmol dm(-3) to 3 nmol dm(-3).     

Direct and indirect identification of the formation of hydroxyaluminosilicates in acidic solutions.

Morin-aluminium fluorescence and membrane filtration were successfully applied to the indirect identification of the formation of hydroxyaluminosilicates (HAS) in acidic solutions of varying pH and of known concentrations of aluminium (Al) and silicic acid (Si(OH)(4)). It was proven to be especially useful in providing evidence of the strong competition between Si(OH)(4) and Al(OH)(3) to condense with hydroxyaluminium templates to form HAS in preference to Al(OH)(3(s)). The aggregation and stability of HAS and Al(OH)(3(s)) were dependent upon both the pH and the [Al] of the solution. The applicability of these indirect techniques was confirmed using the direct observation of HAS in solution by atomic force microscopy (AFM). AFM was also a powerful tool in providing valuable information on the morphology of colloidal HAS of various structures and stoichiometries. The results have provided further confirmation of both the mechanism of HAS formation and the form and stability of HAS in solution. This information is essential to our understanding of the biological availability and hence toxicity of Al in biota, including man.     

Induction of atherosclerosis in Brown Norway rats by immunization with ovalbumin

A study was carried out to establish an animal model that would be suitable for evaluating the role of the diet in immune cell-mediated atherogenesis. Brown Norway rats were initially treated with hypervitamin D2 for 4 days and then fed on an atherogenic diet for 3 months, during which period the rats were either immunized with ovalubumin plus Al(OH)3 (OVA group) or with Al(OH)3 alone (control group) every 3 weeks. Aortic lesions were mainly composed of foam cells, the lesions evaluated by the intimal thickness of the ascending aorta being more severe in the OVA group than in the control group. The OVA group, in comparison with the control group, showed prominently increased serum levels of OVA-specific IgG and rat chymase, an indicator of mast cell degranulation. The intimal thickness was positively correlated with the level of chymase. Immunization had no effect on the serum lipid levels. These results support the hypothesis that mast cells play a role in the early stage of atherosclerosis and suggest that this animal model could be useful for evaluating the role of the diet in immune-related atherogenesis.     

Active immunization against GnRH in pre-pubertal domestic mammals: testicular morphometry,histopathology and endocrine responses in rabbits,guinea pigs and ram lambs

Effective tools for male contraception are important in the control of reproduction in animal populations. The aim of the present study was to evaluate the effects of active immunization against gonadotropin-releasing hormone (GnRH) on male reproductive function assessing testicular morphological changes and serum-gonadotropin levels in pre-pubertal rabbits, guinea pigs and ram lambs. An anti-GnRH vaccine was developed by linking a GnRH-homologous molecule to a tetanus clostridial toxoid (Al(OH)₃ coadjuvant). After vaccination protocols testicular morphometry, histopathological alterations and endocrine responses (FSH, LH, testosterone and cortisol serum levels) were evaluated. Testicular volume was significantly reduced in vaccinated animals with respect to the control group in rabbits, guinea pigs and ram lambs (P<0.05 to P<0.001). The anti-GnRH vaccine generated a reduction in testicular volume of 15-, 27- and 11-fold, respectively. Tubule diameters decreased in the vaccinated group with respect to the control ~2.0-, 1.2- and 3.5-fold, respectively (P<0.001). Tubule, intertubular and lumen volumes significantly decreased in vaccinated rabbits (P<0.05), guinea pigs and ram lambs (P<0.01). Vaccinated animals of the three species showed significant reductions in spermatogonial numbers (10- to 40-fold; P<0.01). Sperm was absent in all seminiferous tubules of all rabbits, and most individuals of guinea pigs (80%) and ram lambs (60%). No significant differences were observed between vaccinated and control groups regarding FSH and LH during the experiments in the three experimental species/models used. Testosterone, however, was only significantly lower (~22-fold, P<0.01) in vaccinated rabbits. In conclusion, the present study demonstrated that pre-pubertal active immunization against GnRH leads to endocrine disruption and marked differences on testicular morphometry, development and activity among lagomorphs, hystricomorphs and ovine species with species-specific sensitivity regarding the anti-GnRH immune response.     

Zonal-Centrifuged Purified Duck Embryo Cell Culture Rabies Vaccine for Human Vaccination

Rabies virus produced in duck embryo cell culture was concentrated from volumes of 14 to 30 liters to 400 to 800 ml by zonal centrifugation. Virus titers of peak fractions were from 100- to 1,000-fold greater than those of the starting material. Vaccines were prepared by combining fractions with peak virus titers and diluting back to 10 times concentration. The resulting beta-propiolactone-inactivated vaccines, when prepared as lyophilized vaccines with AlPO(4) adjuvant diluents, were low in protein nitrogen (0.01 mg/ml), and three of four lots passed the National Institutes of Health potency test when tested as equivalent to a standard 10% suspension of duck embryo or mouse brain tissue vaccine. These vaccines also induced good sero-conversion in adult rabbits after a single 1-ml dose of vaccine. Guinea pigs sensitized with zonal-centrifuged purified duck embryo vaccine (with AlPO(4) adjuvant) did not exhibit anaphylactic shock reactions when challenged with homologous vaccine. Also, no anaphylactic shock reactions were observed when guinea pigs were sensitized with either a 10% experimental duck embryo vaccine or cell culture vaccine and then challenged with the zonal-purified vaccine. However, guinea pigs sensitized with cell culture or zonal-purified vaccine and then challenged with the 10% experimental vaccine did show slight transitory congestion. The 10% experimental whole duck embryo vaccine was responsible for all observed anaphylactic shock reactions whether homologous or heterologous.     

豚鼠眼形觉剥夺后恢复期的生物学参数变化规律探讨

目的探讨豚鼠眼球形觉剥夺后恢复期的生物学参数变化规律。方法普通级2～3周龄豚鼠30只,随机分为两组：①实验组：20只,右眼采用半透明眼罩遮盖进行形觉剥夺4周,随后去遮盖3周,左眼作为自身对照;②正常对照组：10只,双眼不进行任何干预,开放饲养7周。形觉剥夺前、形觉剥夺4周后及去遮盖后第2、6、10、14和21天,测量豚鼠双眼生物学参数：睫状肌麻痹后行带状光检影测量屈光度;A超测量前房深度、晶体厚度和眼轴长度,计算出玻璃体腔长度。结果经过4周形觉剥夺,实验组豚鼠右眼向近视漂移,屈光度为（-2.88±2.30）D,诱导了（-5.50±1.9）D相对近视。去遮盖后,豚鼠右眼重新正视化,屈光度恢复的快速期发生在6 d内,14 d时双眼屈光度差值差异无显著性（t=-2.049,P=0.080）,为（-0.18±0.26）D;右眼玻璃体腔长度缩短,14 d时双眼玻璃体腔长度差值差异无显著性（t=1.652,P=0.14）,为（0.0234±0.0400）mm;右眼眼轴长度缩短,14 d时双眼眼轴长度差值差差异无显著性（t=1.443,P=0.192）,为（0.0183±0.0359）mm。与正常对照组右眼相比,去遮盖6 d,屈光度差异为（-0.48±0.36）D,差异无显著性（t=-1.325,P=0.206）,而2 d时玻璃体腔和眼轴长度差异分别为（0.0961±0.0630）mm、（0.0621±0.0386）mm,差异无显著性（t=1.652,P=0.14;t=1.607,P=0.125）。结论 2～3周龄豚鼠去除形觉剥夺后可以重新进行正视化,伴随玻璃体腔和眼轴长度缩短;去遮盖6 d内为眼生物学参数恢复的主要时期。     

Aluminium rhizotoxicity in maize grown in solutions with Al3+ or Al(OH)-4 as predominant solution Al species

The rhizotoxicity of aluminium at low-pH with Al(3+) and at high pH with Al(OH)-(4) as the main Al species was studied. Aluminium reduced root growth to similar levels at pH 8.0 and pH 4.3, although the mononuclear Al concentration at pH 8.0 was three times lower than at pH 4.3. Al contents of root apices were much higher at pH 8 than at pH 4.3. Callose was induced only marginally at pH 8 and the formation was confined to the epidermis, whereas it proceeded through the cortex with time at pH 4.3. Well-documented genotypical differences in callose formation and Al accumulation could not be found at pH 8. The largest fraction of the root-tip Al was recovered in the cell-wall fraction independent of the solution pH. A sequential extraction of isolated cell walls suggests that most of the cell-wall Al was precipitated Al(OH)(3) at pH 8.0. This can be explained by a drastic pH reduction in the root apoplastic sap to 6.2, whereas at bulk solution pH 4.3 it rose to 5.6. Al precipitation was also confirmed by the microscopic localization of Al. At pH 8, Al could mostly be found in the epidermis, but in the apoplast of the outer cortex at pH 4.3. It is proposed here that at pH 4.3, Al(3+) inhibits root growth through binding to sensitive binding sites in the apoplast of the epidermis and the outer cortex. At pH 8, Al(OH)(3) precipitation in the epidermis causes a mechanical barrier thus impairing the root-growth control of the epidermis.     

Carboxylate composition of root exudates does not relate consistently to a crop species' ability to use phosphorus from aluminium, iron or calcium phosphate sources

* The relationship between carboxylate release from roots and the ability of the species to utilize phosphorus from sparingly soluble forms was studied by comparing Triticum aestivum, Brassica napus, Cicer arietinum, Pisum sativum, Lupinus albus, Lupinus angustifolius and Lupinus cosentinii. * Plants were grown in sand and supplied with 40 mg P kg(-1) in the sparingly soluble forms AlPO(4), FePO(4) or Ca(5)OH(PO(4))(3), or as soluble KH(2)PO(4); control plants received no P. * The ability to utilize sparingly soluble forms of P differed between forms of P supplied and species. Pisum sativum and C. arietinum did not access AlPO(4) or FePO(4) despite releasing carboxylates into the rhizosphere. * Species accessed different forms of sparingly soluble P, but no species was superior in accessing all forms. We conclude that a single trait cannot explain access to different forms of sparingly soluble P, and hypothesize that in addition to carboxylates, rhizosphere pH and root morphology are key factors.     

Evaluation of separation and determination of phytoavailable and phytotoxic aluminium species fractions in soil, sediment and water samples by five different methods

The suggested research deals with the separation of phytoavailable and phytotoxic aluminium species fractions in soil, sediment and water samples by five different procedures (single and sequential extractions, membrane filtration, chelating solid phase extraction and kinetic strength discrimination method). The concentrations of Al in studied samples and relevant plant materials were measured by flame atomic absorption spectrometry (FAAS), optical emission spectrometry with inductively coupled plasma (ICP OES) and UV/visible (VIS) spectrophotometry. The used separation procedures can be divided into three groups. The first group is consisting of weakly efficient single extraction procedures by H(2)O, dilute acetic acid, nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), salicylic acid, ammonium salicylate and 8-hydroxyquinoline, chelating solid phase extraction by resins Iontosorb Oxin and salicyl and kinetic strength discrimination method using 8-hydroxyquinoline which release from the samples only small amounts of phytoavailable and phytotoxic Al by ion-exchange or complexation processes. The more efficient extractions with KCl, NH(4)Cl, CaCl(2), BaCl(2), CuCl(2), LaCl(3), NH(4)F and (NH(4))(2)C(2)O(4) leach approximately the same amounts of phytoavailable Al as the total Al concentrations in plant material (grass Festuca rubra) growing on analysed soils and sediments. The third group of separation procedures contains the most aggressive leaching with Na(4)P(2)O(7), dilute HCl, NH(2)OH.HCl in HNO(3) and H(2)O(2)/ammonium acetate in HNO(3). These extractants release the highest amounts of Al from solid samples, approximately 2-4-fold as the total Al concentrations in relevant plant material and they are unsuitable for purpose of this study.     

Effects of aluminum and deferoxamine on concentration of essential elements in animals experimentally intoxicated with aluminum]

To assess the effect of aluminium intoxication in tissues of experimental animals on Ca, Mg, Zn, Cu, and Fe concentration, aluminium nitrate was administered intraperitoneally to mice at a daily dose of 0.27 mMol/kg for 5 weeks. Concentration of Al, Ca, Mg, Zn, Cu, and Fe were analyzed by atomic absorption spectrometry. The Al content in liver and tibia was significantly higher in treated mice in comparison with control group. In Al loaded tissues the significant increase of all tested essential elements was found. To evaluate the results of DFO treatment on essential elements, mice received 6 times intraperitoneally 3.5 mMol/kg of DFO. This treatment had generally no effect on reduction of Al concentration in tibia and liver, as well as on changes in essential elements concentration.