Greater effect of dietary potassium tripolyphosphate than of potassium dihydrogenphosphate on the nephrocalcinosis and proximal tubular function in female rats from the intake of a high-phosphorus diet

We examined whether a difference in potassium dihydrogenphosphate (KH2PO4) and potassium tripolyphosphate (K5P3O10) as dietary phosphorus sources could differentially effect the nephrocalcinosis and proximal tubular function in female rats. Rats were fed on a diet containing KH2PO4 or K5P3O10, at the normal phosphorus level (normal phosphorus diet) or at a high phosphorus level (high-phosphorus diet) for 21 d. Nephrocalcinosis, as confirmed by a histological examination, was apparent in all rats fed on the high-phosphorus diet, and this condition was more severe in those rats fed on K5P3O10 than in those fed on KH2PO4. As indicators of the proximal tubular function, the N-acetyl-beta-D-glucosaminidase activity in urine and the urinary beta2-microglobulin excretion were significantly increased in those rats fed on the high-phosphorus diet containing K5P3O10. These results indicate that the intake of a high-phosphorus diet, more strongly influenced the nephrocalcinosis and proximal tubular function when K5P3O10 rather than KH2PO4 was used as the dietary phosphorus source.     

Solubility of phosphorus added to four Manitoba soils with different calcium and magnesium contents

Summary The solubility of phosphorus was found to approximate that of dicalcium phosphate dihydrate and/or dimagnesium phosphate trihydrate when KH₂-PO₄, H₃PO₄ and K₂HPO₄ were added to four Manitoba soils. Eighty to one hundred, seventy to ninety and sixty to eighty per cent of the phosphorus added remained in solution when H₃PO₄, KH₂PO₄ and K₂HPO₄ were added, respectively. The solubility of the added phosphorus was high in all samples and relatively soluble compounds, dicalcium phosphate dihydrate and dimagnesium phosphate trihydrate, were most likely formed in the samples indicating that phosphorus added to these soils would be readily available to plants. Associate Professor and Professor respectively.     

Cuticular penetration of potassium salts: Effects of humidity,anions, and temperature

Cuticular penetration of potassium salts across astomatous cuticular membranes isolated from pear and Citrus leaves has been studied. Penetration was a first order process and was greatly affected by humidity and hygroscopicity of salts. Temperature did not significantly influence rates of penetration in the range of 10 – 25 °C. Penetration required dissolution of the salt and this is determined by the point of deliquescence (POD) and humidity. When humidity is above the POD the salt residue on the cuticle dissolves, while below a solid residue is formed and penetration ceases. The POD for K₂CO₃ is 44% at 20 °C and above this humidity salt penetration was possible. Rate constants of penetration increased from 0.022 to 0.045 h^–1 when humidity increased from 50 to 90%. With KCl (POD of 86%) rates were highest at 90% and lower at 100% while with KNO₃ (POD of 95%) and KH₂PO₄ (POD of 97%) highest rates were measured at 100% humidity and at 90% penetration was extremely slow. With KCl, KNO₃ and K₂CO₃ maximum rate constants of penetration across pear CM were around 0.04 – 0.05 h^–1 which correspond to half times of penetration of 14 – 17 h. Rate constants measured with Citrus CM were up to two times higher but response to humidity was similar. The potassium salts studied did not only differ in POD and sensitivity to humidity but also in potassium content, which is highest with K₂CO₃ (57%) and KCl (52%) and much lower with KNO₃ (38%) and KH₂PO₄ (29%). Thus, K₂CO₃ is best suited for foliar applications as rates of penetration were large at 50% humidity and higher, while with the other salts humidity must be 90 – 100% for maximum rates of penetration.     

Thermal Properties of Freeze-Concentrated Sugar-Phosphate Solutions

In order to understand the effect of phosphate salts on the freeze-concentrated glass-like transition temperature (T _g′) of aqueous sugar solutions, two types of sugar (glucose and maltose) and five types of phosphate salts (Na₃PO₄, Na₄P₂O₇, Na₅P₃O₁₀, K₃PO₄, and K₄P₂O₇) were employed, and the thermal properties of various sugar-phosphate aqueous systems were investigated using differential scanning calorimetry. The T _g′ of glucose increased with increasing sodium phosphates up to a certain phosphate ratio, decreasing thereafter. The maximum T _g′ value was slightly higher in the order of Na₃PO₄ > Na₄P₂O₇ ≥ Na₅P₃O₁₀. Maltose-sodium phosphate also showed a similar trend as glucose-sodium phosphate samples. However, the degree of T _g′-rise of maltose systems was much less than that of glucose. It is thought that the T _g′ elevated by the molecular interaction between sugar and phosphate ions will be reduced by hydrated sodium ions. In comparisons between potassium phosphate and sodium phosphate, it was found that sugar-potassium phosphates showed the lower maximum T _g′ at a lower phosphate ratio than sugar-sodium phosphates. In addition, the T _g′ of potassium phosphates dropped sharply in comparison with sodium phosphates at the high phosphate ratio. These results suggest that potassium phosphates are lower T _g′ than sodium phosphates, and that potassium ion plays a better plasticizer than sodium ion. A certain amount of sodium phosphates (Na₃PO₄ and Na₄P₂O₇) caused devitrification. Potassium phosphates, however, did not show devitrification which can be explained by the fact that potassium ion can be dynamically restricted by sugar.     

Modeling some mineral nutrient requirements for micropropagated wild apricot shoot cultures

A response surface methodology (RSM) experimental design was applied for improving micropropagation of a wild apricot, Prunus armeniaca Lam., from the mountains of Kazakhstan. In an initial study, woody plant medium (WPM) mineral nutrients [calcium nitrate, ammonium nitrate, mesos (calcium chloride, potassium phosphate and magnesium sulfate) potassium sulfate and minor nutrients] were tested in a response surface methodology (RSM) experiment. Shoot quality was the best when nitrogen and mesos (CaCl₂, MgSO₄, K₂SO₄, KH₂PO₄) compounds were altered. In this study an expanded mesos optimization experiment was run. Data taken included a subjective quality rating, shoot length, shoot number, leaf color and size, callus and physiological disorders. Data were analyzed by Classification and Regression Tree Analysis (CART), a data mining technique that provides specific cutoff values for data and easy to interpret data trees. The CART analysis indicated that the best quality would be with ≤2.4× WPM levels of KH₂PO₄ and ≤0.75× MgSO₄. Shoot length was affected by K₂SO₄, but most shoots were of good size at any concentration. Shoot multiplication was affected by KH₂PO₄, but there were >5 shoots at any concentration. Leaf color was best with ≤2.41× KH₂PO₄ and ≤1.22× K₂SO₄. Based on the CART analysis, a recommendation for improved mesos compounds was developed. Each of the individual trees was analyzed and the cutoff points determined so that all the growth characteristics could be considered in the final concentrations chosen. Using the combined results from the CART analysis, the suggested medium would include WPM with CaCl₂ 2.7×, MgSO₄ 2.7×, K₂SO₄ 0.8×, KH₂PO₄ 0.75×.     

Effect of Potassium Dihydrogen Phosphate and Bovine Manure Compost on the Degradation of Chlorothalonil in Soil

The effects of potassium dihydrogen phosphate (KH₂PO₄) and bovine manure compost (BMC) on the degradation and metabolism of chlorothalonil were examined in a sandy loam soil under laboratory conditions. In non-sterilized, non-amended soil, chlorothalonil degradation half-life was 8.8 days. However, it was up to 19.0 days in sterilized non-amended soil, suggesting that the degradation rate was about 2-fold slower than that in non-sterilized non-amended soil. Biological mechanisms accounted for 54.7% of chlorothalonil degradation in non-sterilized soil, indicating that the indigenous microorganisms in soil play an important role in the degradation process. In non-sterilized soil, the more acutely toxic metabolite, 4-OH-chlorothalonil (HTI), of chlorothalonil started forming after the second day of incubation. The concentration of HTI reached its maximum level (2.9 μ g g? 1) at 10 days after treatment, and no further degradation of HTI was observed in the following span of 20 days (10–30 days of incubation). However, the degradation rate of chlorothalonil was decreased substantially by the addition of KH₂PO₄ with a half-life of 17.5 days. No formation of HTI was observed before 10 days of incubation and no significant difference of the metabolite concentration at the end of experiment was observed between KH₂PO₄-amended and non-amended treatments, which denoted that the addition of KH₂PO₄ did not reduce the formation of HTI in the longer incubation course. In BMC-amended soil, the degradation rate was about 1.8 times faster than in non-amended soil. At 30 days of incubation, both chlorothalonil and HTI were degraded to a lower level in BMC-amended soil than in non-amended soil. The application of farm litter is a common fertilizing practice in vegetable fields in China, and thus this practice could not only improve soil fertility but also promote the removal of chlorothalonil and its metabolite HTI to further increase safety in crop rotations.     

Enhanced curdlan production in <Emphasis Type="Italic">Agrobacterium</Emphasis> sp. ATCC 31749 by addition of low-polyphosphates

A large amount of adenosine triphosphate with high energy phosphate bonds is required for uridine triphosphate regeneration during curdlan biosynthesis by Agrobacterium sp. ATCC 31749. To supply high energy for curdlan synthesis, three low-polyphosphates (Na₄P₂O₇, Na₅P₃O₁₀, and (NaPO₃)₆) with higher energy phosphate bonds were employed to substitute for KH₂PO₄-K₂HPO₄ in fermentation medium. Two genes encoding the polyphosphate metabolizing enzymes, polyphosphate kinase and exopolyphosphatase, were amplified and showed 95% homology to those in Agrobacterium sp. C58 by sequence analysis. The curdlan yields were enhanced by 23 and 134% when phosphate concentrations 0.024 mol/L of Na₅P₃O₁₀ and 0.048 mol/L of (NaPO₃)₆ respectively, were added in the medium. The maximum curdlan yield of 30 ± 1.02 g/L was obtained with the addition of 0.048 mol/L of (NaPO₃)₆ with 5 g/L CaCO₃ in the medium. When CaCO₃ was removed from the culture and the three lowpolyphosphates were added, the pH and biomass yield dropped remarkably and little or no curdlan was produced. The culture containing 0.048 mol/L of (NaPO₃)₆ was mixed with KH₂PO₄-K₂HPO₄ and CaCO₃ in the medium, but showed no effect on curdlan production. However, curdlan yield was improved by 49 ∼ 60% when CaCO₃ was removed from the medium and KH₂PO₄-K₂HPO₄ acted as a buffer. It appears that the positive effect of (NaPO₃)₆ on curdlan production required the buffering capacity of CaCO₃ and the absence of KH₂PO₄-K₂HPO₄ competing as a phosphate supplier.     

Zum Einfluss von anorganischem Phosphat auf die Phosphohydrolasen von Weizenembryonen (Triticum aestivum L.)

Phosphate is an effective inhibitor of the phosphohydrolases of wheat embryos (Triticum aestivum L.).In vitro the inhibition was competitive with K₁ = 4.48 × 10^-3 M (1.6 × 10^-3 M P₁, applied as KH₂PO₄).In vivo the inhibition with KH₂PO₄ was relatively low during germination (48 h), but inhibition increased when other P₁-compounds were used. In ungerminated embryos the phosphatase activity comprised three isozymes; the pattern of iaozymes changes during germination, but there was no influence of P₁ in comparison with the control. Concluding we may state that the activity of phosphohydrolases is regulated by an inhibition mechanism caused by P_i-concentration.      

Influence of the phosphorus and nitrogen source on nisin production in Lactococcus lactis subsp. lactis batch fermentations using a complex medium

The influence of different phosphorus and nitrogen sources on Lactococcus lactis subsp. lactis NIZO 22186 growth and nisin production was studied in batch fermentations using a complex medium. KH₂PO₄ was found to be the best phosphorus source for nisin production. Increasing initial phosphate concentrations from 0 to 5% KH₂PO₄ exerted a double effect, creating favourable pH conditions and particularly stimulating the nisin production levels, which were highest at 5% KH₂PO₄. Up to now, no such high initial phosphate concentrations have been reported for the production of other antibiotics or bacteriocins. Nisin, a lanthionine-containing peptide antibiotic with bacteriocin properties, clearly behaved as a primary metabolite, since its formation was linked with active growth and was not suppressed by phosphate concentrations up to 5%. A complex medium supplemented with cotton seed meal as nitrogen source also gave very high nisin yields. Correspondence to: L. De Vuyst     

Reduced late-season leaf potassium and phosphorus levels influence decreases in sugar contents of bagged apple fruit

Fruit bagging has been widely used in the fruit production industry; however, in apples, it is known to cause a significant decrease in fruit sugar contents. To address this issue and identify the changes in leaf mineral contents associated with fruit sugar levels in bagged apples, aqueous solutions of 10 g L^?1 CaCl₂, 5 g L^?1 KH₂PO₄, or 2 g L^?1 Na₂B₄O₇·10H₂O were foliar sprayed during four fruit developmental stages. The late-season leaf phosphorus (P) and potassium (K) contents after the rapid fruit growth period and the soluble sugar contents in ripening fruit were significantly lower in bagged fruit than in non-bagged fruit (11.1–15.09 %). The decreases in leaf P and K contents caused by bagging were almost completely compensated for by foliage applications of CaCl₂, KH₂PO₄, or Na₂B₄O₇ during the fruit set period. Therefore, the fruit soluble sugar contents were significantly higher in bagged ripening fruit with foliar spray than in bagged fruit without foliar sprays, reaching the levels of non-bagged apples. The decrease in the sugar contents of bagged apples was closely associated with the decrease in late-season leaf P and K levels caused by fruit bagging.     

Identification of Mutations Involved in the Requirement of Potassium for Growth of Typical Melissococcus plutonius Strains

Melissococcus plutonius is a fastidious honeybee pathogen, and the addition of KH₂PO₄ to culture medium is required for its growth. Using genome sequences and a newly developed vector, we showed that mutations in genes encoding Na⁺/H⁺ antiporter and cation-transporting ATPase are involved in the potassium requirement for growth.     

Characterization of phosphate absorption in maize root cortex segments

Uptake of phosphate ions by 1 mm segments of isolated maize root cortex layers was studied. Cortex segments (from roots of 8 days old maize plants) absorb phosphate ions from 1 mM KH₂PO₄ in 0.2 mM CaSCO₄ at the average rate of 34.3 ±3.2 μg P_i g^?1 (fr. m.) h^?1,i.e. 0.35± 0.02 μmol P_i g^?1 (fr. m.) h^?1. Phosphate uptake considerably increases after a certain period of “augmentation”,i.e. washing in aerated 0.2 mM CaSO₄. This increase is completely blocked by the presence of 10 μg ml^?1 cycloheximide. The relation of uptake rate to phosphate concentration in the medium was shown to have 3 phases in the concentration range of 0.02 - 40 mM. Transition points were found between 0.8–1 mM and 10–20 mM. Following K_m and V_max values were found: K_m[mM] : 0.37 - 3.82 - 27.67 V_max[μg P_i g^?1 (fr. m.) h^?1] : 3.33 - 39.40 - 66.67 We have found no sharp pH optimum for phosphate uptake. It proceeds at almost constant rate till pH 6.0 and then the uptake rate drops with increasing pH. At low phosphate concentrations (1 mM) the lowest uptake rate was found at 5 and 13 °C, while the uptake is higher at 5 °C than at 13 °C at phosphate concentrations higher than 1 mM. At these concentrations uptake rate at 35 °C is lower than at 25 °C. Phosphate uptake considerably decreased in anaerobic conditions. DNP and iodoacetate (0.1 mM) completely blocked phosphate uptake from 1 mM KH₂PO₄, while uptake from 5 and 10 mM KH₂PO₄ was left unaffected by these substances. The inhibitors of active - SH groups NEM and PCMB inhibited phosphate uptake: 10^?3 M NEM by 81.6%, 10⁴ M NEM by 42% and 10^?4 M PCMB by 42%.     

Partitioning of xylanolitic complex from Penicillium janthinellum by an aqueous two-phase system

This work evaluates the influences of five parameters (pH, PEG molecular mass, PEG concentration, concentration of buffer K₂HPO₄–KH₂PO₄ and NaCl concentration) on xylanolitic complex partitioning produced by P. janthinellum in aqueous two-phase systems, using a 2⁵ factorial experimental design. A mathematical model to quantify the influence of these parameters was attained and statistically tested. The optimum point for total protein extraction was obtained under the following conditions: pH 7.0, PEG 10 000, 3.67% PEG, 10% potassium phosphate and 12.4% NaCl. The partition coefficient (K) value experimentally obtained was 5.25 and that predicted by the model was 5.89.     

Effect of Potassium, and Abscisic and Indole-3-Acetic Acids, on Maize Root Xylem Exudation and Potassium Efflux

The influence of potassium sulfate, abscisic acid (ABA) and indole-3-acetic acid (IAA) solutions on xylem exudation rate and potassium efflux from the apical cut end of root tips of intact maize (Zea mays L. cv. Dnepropetrovskaya) seedlings was studied. Foliar application of 5 mM K₂SO₄ considerably stimulated the exudation rate. The application of ABA and IAA (1 mM) also induced a high rate of xylem exudation, K⁺ efflux being simultaneously increased. This revised version was published online in July 2006 with corrections to the Cover Date.     

Inhibition of ion accumulation in maize roots by abscisic acid

Summary An inhibition of root growth, a decrease in the amount of potassium (as ⁸⁶Rb) and phosphate (³²P) accumulation by the root, and a partial depolarization of transmembrane electropotential were observed to develop with a similar time course and to a similar extent when intact maize (Zea mays L.) roots were treated with 10^-5 M abscisic acid (ABA). Potassium uptake was inhibited by ABA when excised, low-salt roots were bathed in KCl, KH₂PO₄, or K₂SO₄. ABA did not affect the ATP content of the tissues, the activity of isolated mitochondria, nor the activity of microsomal K⁺-stimulated ATPases.     

Interference of some aqueous two-phase system phase-forming components in protein determination by the Bradford method

The interference of some specific aqueous two-phase system (ATPS) phase-forming components in bovine serum albumin (BSA) determination by the Bradford method was investigated. For this purpose, calibration curves were obtained for BSA in the presence of different concentrations of salts and polymers. A total of 19 salts [Na₂SO₄, (NH₄)₂SO₄, MgSO₄, LiSO₄, Na₂HPO₄, sodium phosphate buffer (pH 7.0), NaH₂PO₄, K₂HPO₄, potassium phosphate buffer (pH 7.0), KH₂PO₄, C₆H₈O₇, Na₃C₆H₅O₇, KCHO₂, NaCHO₂, NaCO₃, NaHCO₃, C₂H₄O₂, sodium acetate buffer (pH 4.5), and NaC₂H₃O₂] and 7 polymers [PEG 4000, PEG 8000, PEG 20000, UCON 3900, Ficoll 70000, PES 100000, and PVP 40000] were tested, and each calibration curve was compared with the one obtained for BSA in water. Some concentrations of salts and polymers had considerable effect in the BSA calibration curve. Carbonate salts were responsible for the highest salt interference, whereas citric and acetic acids did not produce interference even in the maximum concentration level tested (5 wt%). Among the polymers, UCON gave the highest interference, whereas Ficoll did not produce interference when used in concentrations up to 10 wt%. It was concluded that a convenient dilution of the samples prior to the protein quantification is needed to ensure no significant interference from ATPS phase-forming constituents.     

The effects of temperature and IAA concentration on the latent period for IAA-induced rapid growth of Avena coleoptile segments

Summary Indoleacetic acid buffered at pH 7.0 induces a high growth rate in Avena coleoptile segments after a latent period, the duration of which is dependent upon both IAA concentration and temperature. A minimum latent period of 7.3 min is observed at 25° C with 10^-3 M IAA in phosphate buffer at pH 7.0.In contrast, 5×10^-3 M IAA made up in 0.01 M KH₂PO₄ alone, promotes elongation almost immediately, regardless of whether the segments have been previously incubated in 0.01 M KH₂PO₄ at pH 4.7, or phosphate buffer at pH 7.0. This immediate response is unaffected by 10^-4 M KCN which abolishes the rapid growth induced by 5×10^-3 M IAA buffered at pH 7.0 but does not affect the immediate appearance of low-pH-induced growth. Since we consistently find solutions of 5×10^-3 M IAA in 0.01 M KH₂PO₄ to have a pH of 3.5, our results indicate that the immediate growth response elicited by this solution is attributable to its low pH rather than to the presence of IAA as previously reported in the literature.     

Formation of Psicose from Glucose in Autoclaved and Uninoculated Fermentation Media

When a fermentation medium consisting of the high concentration of K₂HPO₄ and KH₂PO₄ and glucose as a sole carbon source is autoclaved in the alkaline side, an unknown sugar is formed. This sugar is identified as psicose by paper chromatography and high-voltage paper electrophoresis. The notion that weak alkali causes the isomerization of reducing sugar could account for the formation of psicose in the medium. It is thus concluded that psicose is chemically formed from glucose in the alkaline side and in the high concentration of K₂HPO₄ and KH₂PO₄ during autoclaving.     

Bioavailability of phosphorus in corn gluten feed derived from conventional and low-phytate maize

Young chicks were used to determine phosphorus (P) bioavailability in corn gluten feed (CGF) derived from a conventional maize hybrid (CCGF) or one containing higher protein, higher oil, and lower phytate content (LPCGF). The nutritionally-enhanced maize used to produce LPCGF contained higher CP, total P, available P, and oil concentrations but less starch content compared to the hybrid used to produce CCGF. Similarly, LPCGF contained slightly higher CP and total P compared to CCGF. From 8 to 22 days of age, female chicks were fed a cornstarch–dextrose–soybean meal basal diet containing 1 g available P/kg, or the basal diet supplemented with two concentrations of P (0.5 and 1.0 g/kg) from KH₂PO₄ or two concentrations of the CGF samples (75 and 150 g/kg). Bioavailability of P based on tibia bone ash was much higher for LPCGF than for CCGF. Bioavailability of P relative to the KH₂PO₄ standard was 0.464±0.13 for CCGF and 0.898±0.12 for LPCGF based on slope-ratio methodology. The results indicated that P bioavailability in CGF is about twice as high as that in maize, and also that LPCGF has roughly twice as much bioavailable P as CCGF.     

Formation of Crystalline δ-Endotoxin or Poly-β-Hydroxybutyric Acid Granules by Asporogenous Mutants of Bacillus thuringiensis

Parental strains and asporogenous mutants of Bacillus thuringiensis subspp. kurstaki and aizawai produced high yields of δ-endotoxin on M medium, which contained 330 μg of potassium per ml, but not on ST and ST-a media, each of which contained only 11 μg of potassium per ml. On ST and ST-a media, refractile granules were formed instead. These granules had no insecticidal activity against silkworms and were isolated and identified as poly-β-hydroxybutyric acid. Supplementation of the potassium-deficient ST-a medium with 0.1% KH₂PO₄ (3.7 mM) led to the formation of crystalline δ-endotoxin. The replacement of KH₂PO₄ with equimolar amounts of KCl, KNO₃, and potassium acetate or an equivalent amount of K₂SO₄ had a similar effect, whereas the addition of an equimolar amount of NaH₂PO₄ or NH₄H₂PO₄ did not cause the endotoxin to form. An asporogenous mutant, B. thuringiensis subsp. kurstaki strain 290-1, produced δ-endotoxin on ST-a medium supplemented with 3 mM or more potassium but formed only poly-β-hydroxybutyric acid granules on the media containing ≤1 mM potassium. These results clearly indicate that a certain concentration of potassium is essential for the fermentative production of δ-endotoxin by these isolates of B. thuringiensis. Manganese could not be substituted for potassium. Phosphate ions stimulated poly-β-hydroxybutyric acid formation by strain 290-1. The sporulation of B. thuringiensis and several other Bacillus strains was suppressed on the potassium-deficient ST medium. This suggests that potassium plays an essential role not only in Bacillus cell growth and δ-endotoxin formation but also in sporulation.