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PubMed1951

The mortality of bacteriophage containing assimilated radioactive phosphorus.

The bacteriophage T4 containing assimilated radioactive phosphorus is inactivated at a rate proportional to the specific radioactivity of the constituent phosphorus. The beta radiation from the phosphorus makes a negligible contribution to this effect. The inactivation is therefore a direct consequence of the nuclear reaction, which kills the phage with an efficiency of about 1/12. Several phages related to T4 behave similarly. When radioactive phage is grown from a seed of non-radioactive phage, all of the phage progeny are subject to killing by radioactive decay. The phage is killed by beta radiation from P(32) with an efficiency of about 1/100 per ionization within the particle volume. Bacteriophage T4 and its relatives contain about 500,000 atoms of phosphorus per infective particle. Virtually all this phosphorus is adsorbed to bacteria with the specificity characteristic of the infective particles, and none of it can be removed from the particles by the enzyme desoxyribonuclease. The phosphorus content per particle, together with the published data on analytical composition, indicates a particle diameter close to 110 mmicro for the varieties of phage studied.

Bacteriophages↗
PubMed1964

ACCUMULATION OF PHOSPHORUS COMPOUNDS BY MUCOR RACEMOSUS.

James, A. W. (The Pennsylvania State University, University Park), and L. E. Casida, Jr. Accumulation of phosphorus compounds by Mucor racemosus. J. Bacteriol. 87:150-155. 1964.-In glucose-inorganic salts media containing excess KH(2)PO(4), Mucor racemosus accumulated 5 to 6% phosphorus on a dry-weight basis in its mycelium. Fractionation of phosphorus compounds in young, rapidly growing mycelium revealed that approximately 58% of this phosphorus was in the form of inorganic polyphosphate; nucleic acids accounted for an additional 17% of the total phosphorus. Upon further growth, morphological changes were observed in many of the hyphae, and polyphosphate appeared in the culture media. In media containing limited amounts of KH(2)PO(4), exogenous polyphosphate was utilized by M. racemosus, and the phosphorus content of the mycelium decreased to approximately 0.3%.

Culture Media↗
PubMed2005

Analytical phosphorus fractionation in sewage sludge and sediment samples.

The Standards, Measurements and Testing (SMT) harmonized procedure for phosphorus fractionation in freshwater sediments (SMT protocol), which was developed within the framework of the Standards, Measurements and Testing (SMT) Programme of the European Commission, has been applied to different environmental samples such as sewage sludge, river and marine sediments. The phosphorus contents in the extracts were spectrophotometrically determined; the measurement conditions and the matrix effects were evaluated for each fraction. The partitioning patterns obtained for sewage sludge and sediment samples reveal that the distribution between inorganic and organic phosphorus forms is independent of the matrix composition of the samples. In addition, a higher available phosphorus content was found in sewage sludges due to the higher percentages of labile phosphorus forms, which suggests possible internal phosphorus release. Finally, one simplified pseudototal microwave digestion method was performed for total phosphorus determination which was validated by its application to the reference material BCR-684.

Journal Article↗
PubMed1970

Acetylene reduction assay for determination of phosphorus availability in wisconsin lakes.

Phosphorus-starved cells of Anabaena flos-aquae rapidly increase their capacity to reduce acetylene to ethylene when they receive phosphorus. This response may be used as a bioassay for detecting available phosphorus in aquatic ecosystems. The sensitivity of the method compares favorably with conventional methods for measuring dissolved orthophosphate, and has the additional advantage that it measures available phosphorus. Studies on Wisconsin lakes show that available phosphorus generally is present, that the concentrations are higher at the lower depths than at the surface, and that there may be diurnal variations in the available phosphorus content of surface waters. Important sources of available phosphorus in Lake Mendota are the waters below the thermocline and the input from storm sewers.

Journal Article↗
PubMed1966

Effect of aluminum on the uptake and metabolism of phosphorus by barley seedlings.

The uptake of P(32) and its incorporation into phosphorylated compounds was examined in the roots of barley seedlings which had been pretreated with aluminum.The rate at which phosphorus increased in Al-roots was greater than in controls, especially during the first 15 minutes of incubation. It was shown that the increased phosphorus in Al-roots was P(i) and that it was almost completely exchangeable. Similar increases over controls were found when root segments were incubated in phosphorus solutions containing 10(-3)m DNP and at low temperature. The increased P(i) in Al-roots did not result in an increase in the total amount of phosphorus incorporated into phosphorylated compounds.Aluminum treatment markedly decreased the incorporation of P(32) into sugar phosphates but increased the pool size of ATP and other nucleotide triphosphates present in the roots. The specific activities of P(32) in ATP in Al-roots and controls were similar indicating that the rates of ATP synthesis were similar in each case.Preliminary investigations showed that aluminum citrate inhibited both purified yeast hexokinase and phosphorylated sugar production by crude mitochondrial extracts from barley roots.The results suggest that there are 2 reactions between aluminum and phosphorus: 1) at the cell surface or in the free space which results in the fixation of phosphate by an adsorption-precipitation reaction; 2) within the cell, possibly within the mitochondria, which results in a marked decrease in the rate of sugar phosphorylation, probably effected by the inhibition of hexokinase. The evidence does not support the view that aluminum enhances phosphorus uptake or that the superficial reaction between aluminum and phosphate interferes with phosphorus transport.

Journal Article↗
PubMed1985

Osmoregulation in Cotton in Response to Water Stress : III. Effects of Phosphorus Fertility.

Cotton (Gossypium hirsutum) (L.) was grown in a sand and nutrient solution system at two levels of phosphorus (0.5 and 5.0 millimolar). Within each phosphorus treatment, plants were either watered daily or acclimated to water stress by subjection to several water stress cycles.Stress acclimation increased leaf starch at the low phosphorus level, but not at the high phosphorus level. High phosphorus increased leaf sucrose and glucose concentration in both acclimated and nonacclimated plants, but had little effect on osmotic adjustment or the relationship between turgor and water potential.In nonacclimated plants, high phosphorus increased both leaf conductance and photosynthesis at high water potentials. In acclimated plants, high phosphorus increased photosynthesis but decreased conductance, thus increasing water use efficiency at the single leaf level.

Journal Article↗
PubMed1983

Phosphate uptake by renal membrane vesicles of rabbits adapted to high and low phosphorus diets.

Renal adaptation to changes in phosphate intake was studied by comparing phosphate uptake by proximal tubule brush border membrane vesicles from rabbits on a relatively high or low phosphorus diet. The low phosphorus diet increased Na+ gradient-dependent phosphate uptake. Uptake in the absence of Na+ and in the presence of Na+, but no gradient, was not significantly affected. The phosphorus diet did not alter Na+ gradient-dependent D-glucose and L-proline uptake. The low phosphorus diet increased Vmax; affinity for phosphate was not appreciably changed. At all concentrations of extravesicular Na+, phosphate uptake was higher in membrane vesicles from animals fed the low phosphorus diet; the kinetics of the phosphate uptake system, with respect to Na+, was also altered by the change in dietary phosphate. These findings suggest that adaptation involves an alteration in the rate of translocation of the Na+-phosphate carrier when energized by a Na+ gradient driving force rather than a change in the number of Na+-phosphate carrier sites. With membrane vesicles from rabbits fed a low phosphorus diet, phosphate uptake increased several-fold when the pH of the uptake medium was raised, whereas with membrane vesicles from animals fed a high phosphorus diet the enhancement of uptake with alkalinization was relatively small. Irrespective of the diet, divalent phosphate was the probable preferred species for transport. Dietary adaptation was associated, however, with an alteration in the pH dependency of the transport system per se. These findings provide evidence that the adaptation of the kidney phosphate transport system to dietary phosphate load involves an intrinsic change in the Na+-phosphate carrier.

Animals↗
PubMed1995

Tissue specificity and mechanism of vitamin D receptor up-regulation during dietary phosphorus restriction in the rat.

Dietary phosphorus restriction up-regulates intestinal vitamin D receptor (VDR), but the tissue specificity of the up-regulation and the mechanism of receptor accumulation remain unknown. Therefore, the effects of low phosphorus diet (LPD) on VDR content in intestine, kidney, and splenic monocytes/macrophages were examined. Male Sprague-Dawley rats weighing 50-100 g were fed a normal diet (NPD; 0.6% Ca, 0.65% P) as controls followed by an LPD (0.6% Ca, 0.1% P) for 1-10 days (D1-D10). LPD rapidly decreased serum P levels by D1 from 11.11 +/- 0.19 mg/dl (mean +/- SE) to 4.98 +/- 0.37 mg/dl (n = 9). LPD increased total serum Ca from 10.54 +/- 0.09 mg/dl to 11.63 +/- 0.15, 12.17 +/- 0.15, and 12.39 +/- 0.18 mg/dl by D1, D2, and D3, respectively, and then remained stable. Serum 1,25-(OH)2D3 rapidly increased from 123 +/- 5.4 pg/ml to 304 +/- 35 pg/ml by D1, reached a plateau through D5, and then gradually increased to 464.9 +/- 27.7 pg/ml by D10. Intestinal VDR quantitated by ligand binding assay increased 3.5-fold from 169.6 +/- 13.7 fmol/mg of cytosol protein in rats fed NPD (n = 12) to a peak of 588.3 +/- 141.88 fmol/mg of protein by D3 (n = 6; p < 0.001) and then decreased to a plateau level of 2.5-fold greater than NPD (p < 0.05) during D5 to D10. In contrast, LPD did not up-regulate kidney or splenic monocyte/macrophage VDR. Northern blot analysis showed that intestinal VDR mRNA increased 2-fold by D2 (n = 3) of LPD and then gradually decreased to control levels after D5. In contrast, kidney VDR mRNA levels did not change during the first 5 days of P restriction and then subsequently decreased to 50% of NPD controls. The results of these studies indicate that VDR up-regulation during dietary phosphorus restriction is tissue-specific and that the mechanism of the up-regulation is time-dependent. Acutely (D1-D5), phosphorus restriction up-regulates intestinal VDR through increased VDR gene expression, whereas chronic (D5-D10) phosphorus restriction appears to alter VDR metabolism through nongenomic mechanisms that are consistent with prolongation of the half-life of the receptor. The nature of the tissue-specific regulation of VDR during phosphorus restriction remains to be determined.

Animals↗
PubMed2005

Matrix effects during phosphorus determination with quadrupole inductively coupled plasma mass spectrometry.

A quadrupole inductively coupled plasma mass spectrometer was evaluated for use in the detection of phosphorus. The influences of nitric acid and methanol (simulating the composition of a sample solution after nitric acid digestion) on phosphorus determination were studied using two different measuring methods at different plasma conditions: detection of phosphorus ions at m/z 31 and detection of phosphorus oxide ions at m/z 47. The existence of polyatomic interferences at m/z 31 and 47 was explored. Nitric acid and methanol are shown to be the sources of polyatomic ions and therefore cause poorer detection limits. Better detection limits were achieved in such matrices when phosphorus was detected as 31P+. The presence of methanol improves the system sensitivity towards phosphorus sevenfold; however, this positive effect is hindered by the high background signal due to carbon-based polyatomic ions. For samples with an organic matrix an appropriate mineralization procedure should be applied (high excess of nitric acid and high temperature) to quantitatively oxidize organic compounds to carbon dioxide, which is easily removed from the sample, in order to achieve correct results.

Carbon Dioxide↗
PubMed1997

Digestibility of phosphorus in protein-rich ingredients for pig diets.

Two experiments were run to determine the digestibility of phosphorus in different vegetable and animal proteins for the pig diet. Each experiment comprised two 4 x 4 Latin squares run concurrently. Pigs initially weighing 30 kg were kept in metabolism crates and fed twice daily at about 2.5-fold metabolisable energy requirement for maintenance. A semi-purified basal diet low in phosphorus and without intrinsic phytase activity was fed either alone or after blending into mixtures with one of the ingredients to be tested. Mixtures were calculated to contain not more than 2 g digestible P/kg DM and between 5.0 and 6.0 g Ca/kg DM. Faeces and urine were quantitatively collected for 8 days after 7 days of adaptation. Phosphorus digestibility for ingredients under test was calculated assuming the digestibility of phosphorus from the basal diets to be constant in all diets. P digestibilities in solvent extracted soybean meal from dehulled seed, rapeseed and solvent extracted rapeseed meal were 37, 42 and 24%, respectively. Supplementation of a microbial phytase (750 U/kg diet) improved digestibility coefficients significantly to 76, 66 and 73%, respectively. Digestibility of phosphorus in 3 different batches of fish meal ranged from 85 to 90%, without significant differences between batches. In 3 different types of carcass meal, digestibility coefficients were 80, 82 and 83% without significant differences between types, and digestibility of phosphorus from bone meal was 80%.

6-Phytase↗
PubMed2004

Spatial mapping of phosphorus influx in bean root systems using digital autoradiography.

A novel technique was developed to spatially map the phosphorus net influx capacity in intact root systems. The method is based on digital autoradiography and permits the quantification of phosphorus influx at high spatial resolution (2 mm). Roots of 18-d-old common bean plants were exposed to (32)P-labelled orthophosphate, quickly frozen, excised, lyophilized, scanned, and exposed to a storage phosphor screen. Plots of (32)P content versus root length (distance from the root tip or from the base of the root) were obtained for three different root classes: basal, basal laterals, and taproot laterals. Radioactivity detected by filmless autoradiography correlated well (r(2)=0.99) with measurements made by scintillation counting. Basal roots absorbed 2.5 times and 1.9 times more phosphorus than the taproot lateral and basal lateral root classes, respectively, in the first 20 mm from the root apex. External phosphorus markedly affected influx: roots averaged 5, 16, and 34 pmol P min(-1) in the apical 20 mm when exposed to 1, 5, and 10 microM P solutions, respectively. The spatial pattern of phosphorus influx along the root axes of the different root classes was rather homogeneous when measured on a root surface area basis. Phosphorus influx in the older segments of basal roots (those next to the hypocotyl) did not differ from the newer segments close to the root apex. However, a heterogeneous pattern was detected for basal roots when measured on a length basis, indicating that both root class and diameter constitute main factors controlling the spatial pattern of net influx.

Autoradiography↗
PubMed2003

[Early treatment of secondary hyperparathyroidism in moderate renal insufficiency: low-phosphorus diet versus calcium carbonate].

Calcitriol deficiency and phosphorus retention are mechanisms involved in the pathogenesis of renal hyperparathyroidism. The aim of this study was to evaluate the effect of dietary phosphorus restriction versus calcium carbonate treatment for one month on PTH and calcitriol levels in patients with mild renal failure. We studied two groups of patients: Group I: 21 patients (14M/7F); mean age 61 years old; mean glomerular filtration rate 51 ml/min. Their diet contained phosphorus 700 mg/day. Group II: 30 patients (21M/9F); mean age 58; mean glomerular rate 56 ml/min. They were divided in two subgroups: 18 patients treated with calcium carbonate 2.5 g/day and 12 patients with 5 g/day. Serum PTH, calcitriol, 25(OH)D3, calcium, phosphorus and urinary excretion of calcium and phosphorus were measured before and after a 30 day period. The low phosphorus diet (Group I) resulted in a significant decrease in PTH levels (81.3 +/- 35 vs 71 +/- 39 pg/ml, p < 0.05) and significant increase in calcitriol levels (22.4 +/- 4.4 vs 33.4 +/- 7.5 pg/ml, p < 0.05). In our study calcium carbonate treatment (Group II) had no effect on PTH and calcitriol levels.

Aged↗
PubMed1979

[Idiopathic hypercalciuria: effects of acute phosphorus deficiency (author's transl)].

Eleven patients with kidney stone disease and idiopathic hypercalciuria (urinary calcium above 4 mg/kg/j), without phosphorus renal leak and 6 control subjects have been put for 3 days on a diet containing 1 g calcium and 1 phosphorus daily (period A), and then for 4 days on a diet containing 1 g calcium, 450 mg phosphorus and 3 g aluminium hydroxyde daily (period B). During period A, no significant difference in blood calcium, phosphorus and magnesium, not in phosphaturia, rate of phosphorus reabsorption (RPR) and ratio maximum RPR/creatinine clearance was found between the two groups. After 2 days on a low phosphate diet (period B) the blood phosphorus decreased significantly in the hypercalciuric patients but not in the control subjects, thus revealing among the forme a latent abnormality in the retention of phosphates. This abnormality could play an important role in the pathogenesis of hypercalciuria.

Adult↗
PubMed1996

Acute recumbency and marginal phosphorus deficiency in dairy cattle.

Because of a mixing error at a local feed mill, a diet marginally deficient in phosphorus, compared with recommendation from the National Research Council, was fed to a high-producing dairy herd for 5 months. Two mature cows in early lactation became recumbent. Serum phosphorus concentration in 1 cow was low (1.8 mg/dl), but was not measured in the other cow. Ten other high-producing, first-lactation cows in the herd developed severe lameness. Results of analysis of rib bone samples from the recumbent cows were consistent with changes associated with demineralization. Bone ash, calcium, phosphorus, and magnesium concentrations were lower than published ranges for healthy cattle. Serum calcium, phosphorus, and magnesium concentrations in 8 unaffected cows were normal. For 6 unaffected cows, mean serum hydroxyproline concentration was higher during the period that the phosphorus-deficient diet was fed than when an adequate diet was fed. Moderate (15%) restrictions in dietary phosphorus intake, compared with National Research Council recommendations, can possibly result in health problems in high-producing dairy cattle.

Acute Disease↗
PubMed2003

Simultaneous nitrification, denitrification, and phosphorus removal in a lab-scale sequencing batch reactor.

Simultaneous nitrification and denitrification (SND) via the nitrite pathway and anaerobic-anoxic-enhanced biological phosphorus removal (EBPR) are two processes that can significantly reduce the energy and COD demand for nitrogen and phosphorus removal. The combination of these two processes has the potential of achieving simultaneous nitrogen and phosphorus removal with a minimal requirement for COD. A lab-scale sequencing batch reactor (SBR) was operated in alternating anaerobic-aerobic mode with a low dissolved oxygen (DO) concentration (0.5 mg/L) during the aerobic period, and was demonstrated to accomplish nitrification, denitrification, and phosphorus removal. Under anaerobic conditions, COD was taken up and converted to polyhydroxyalkanoates (PHAs), accompanied by phosphorus release. In the subsequent aerobic stage, PHA was oxidized and phosphorus was taken up to <0.5 mg/L by the end of the cycle. Ammonia was also oxidized during the aerobic period, but without accumulation of nitrite or nitrate in the system, indicating the occurrence of simultaneous nitrification and denitrification. However, off-gas analysis showed that the final denitrification product was mainly nitrous oxide (N(2)O), not N(2). Further experimental results demonstrated that nitrogen removal was via nitrite, not nitrate. These experiments also showed that denitrifying glycogen-accumulating organisms (DGAOs), rather than denitrifying polyphosphate-accumulating organisms (DPAOs), were responsible for the denitrification activity.

Acetic Acid↗
PubMed1975

Effect of hydrochlorothiazide on phosphorus during treatment with diphosphonate.

The effects of probenecid and hydrochlorothiazide on renal handling of phosphorus during hyperphosphatemia induced by diphosphonate (ethane-1-hydroxy-1, 1-diphosphonate, EHDP) was studied. Measurements of calcium, phosphorus, and creatinine clearance were performed in 2 sessions on each of 3 consecutive days in 10 normal fasting volunteers during the morning hours from 8 A.M. to 12 noon. During 2 to 3 wk thereafter, each subject was treated with EHDP, 30 mg/kg/day. The second group of studies were performed in the same manner as the first except the EHDP administration was continued throughout. EHDP caused elevation of serum phosphorus in all cases. Probenecid did not affect urine phosphorus. Hydrochlorothiazide caused a transient phosphaturia of similar magnitude in the EHDP treated and untreated states. Creatinine clearance was not affected by any of the treatments and urine calcium was decreased by EHDP. It was concluded that hydrochlorothiazide inhibits tubular reabsorption of phosphorus but that it does not affect the mechanism whereby EHDP causes increased tubular reabsorption of phosphorus. Chronic administration of hydrochlorothiazide along with EHDP may inhibit hyperphosphatemia and may change the bone effects of EHDP.

Adult↗
PubMed1987

Influence of hydrocortison acetate on the evolution of the nutritive utilization of calcium and phosphorus and their contents on the longissimus dorsi muscle during gestation in the rat.

The evolution of the nutritive utilization and plasma and muscular content of calcium and phosphorus in rats is studied, as well as the influence that hydrocortisone acetate has (4 mg/100 g weight and day), on them. In pregnant rats injected with saline solution, the retention of calcium is higher on the days 15-18 as a consequence of the increase on the net absorption of the cation. The balance of phosphorus reaches its maximum hight on days 18-21 of gestation, due to the decrease of the urinary excretion during these days. The administration of hydrocortisone acetate to pregnant rats originate a decrease of the net absorption and an increase of the urinary excretion of calcium and phosphorus, which leads to significantly lower balances than those of animals injected with saline solution. The hormone maintains the animals in a negative balance of phosphorus until day 18 of gestation. Besides, it impedes the high retention of calcium which is found with the control pregnant rats on days 15-18. In general, the content in calcium and phosphorus by gram of dry matter of Longissimus dorsi muscle is not modified during gestation. From day 9 of the treatment with hydrocortisone acetate a significant decrease of calcium and phosphorus of the muscle is observed, that in calcium is the more marked the more the treatment is prolonged. This effect seems to be due to the catabolic action of the hormone.

Animals↗
PubMed1992

Dietary restriction of calcium, phosphorus, and vitamin D elicits differential regulation of the mRNAs for avian intestinal calbindin-D28k and the 1,25-dihydroxyvitamin D3 receptor.

We investigated the regulation of 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3]-induced calbindin-D28k (CaBP) and of the vitamin D receptor (VDR) by evaluating CaBP protein, CaBP mRNA, and VDR mRNA under conditions of altered intake of vitamin D, calcium, or phosphorus. Chickens were maintained for 10 days on one of four diets: vitamin D-deficient, normal (1.0% Ca and 1.1% P), low calcium (0.1% Ca and 1.2% P), and low phosphorus (1.1% Ca and 0.3% P). CaBP was undetectable in D-deficient duodena and was elevated above normal values by low-calcium (3.1-fold) and low-phosphorus (2.3-fold) intake. Contradictory to published data, we observed a correlation between CaBP protein and mRNA levels in that the CaBP mRNA was absent in D-deficient intestine and augmented threefold and twofold in low-calcium and low-phosphate duodena, respectively. In contrast, VDR mRNA concentrations were identical in vitamin D-deficient and normal duodena, implying that intestinal VDR is not dependent upon 1,25-(OH)2D3 for basal expression. Chickens fed a low-phosphorus diet displayed a twofold increase in VDR mRNA, but those fed a low-calcium diet exhibited a dramatic decrease in VDR mRNA. These data show that CaBP mRNA and protein levels are modulated in a tightly coupled fashion, and they are consistent with previous conclusions that augmented circulating 1,25-(OH)2D3 stimulates CaBP expression when dietary calcium or phosphorus is limiting. However, a more complex regulation of VDR expression occurs in that low-phosphorus restriction enhances VDR mRNA levels, possibly via increased circulating 1,25-(OH)2D3. Conversely, reduced dietary calcium diminishes VDR mRNA despite increased circulating 1,25-(OH)2D3, indicating that another factor, such as parathyroid hormone, is a predominant downregulator of VDR.

Animals↗