Phosphorus kinetics in growing hair sheep

Kinetics modelling was used to study the effects of different dietary phosphorus (P) levels on P metabolism in young sheep. An experiment was conducted with 12 Santa Ines lambs receiving a basal diet of a hay-concentrate mixture. Different amounts of dicalcium phosphate were added to the basal diet, to give the following treatments levels of 0, 1.5, 3 and 4.5 g/animal/day. The isotopic dilution technique (32 p) was used for analyze four compartments: gastrointestinal tract, plasma, bone and soft tissues (liver, heart, kidney and muscle), as well as nutrient flows between them. All P flows showed a positive linear or exponential relationship with P intake. Both incorporation and reabsorption in bone and soft tissue increased with increasing P levels in the diet, with positive retention above 3 g/day. On the 4.5g P/day treatment, reduced P absorption and increased P in the faeces from dietary origin was noted. Three g/day of P treatment was sufficient to meet soft tissue requirements for young sheep. (C) 2008 Elsevier B.V. All rights reserved.

Nitrogen, phosphorus and potassium dose effect in the graft box of lemon tree (of the family Rutaceae) nutrition and production.

Nitrogen, phosphorus and potassium dose effect in the graft box of lemon tree (of the family Rutaceae) nutrition and production. The aim of the study was to evaluate the graft box of lemon tree (of the family Rutaceae) nutritional state and its components of growth in function of nitrogen, phosphorus and potassium dose by fertilization. The experimental outlining was entirely made casually in factorial scheme 3(3) + 1, being 3 factors (nitrogen, phosphorus and potassium - NPK), 3 doses and in evidence (without fertilization), with 3 repetitions. The experimental milt was constituted by two tubes of 2,8 cm diameter and 12,3 cm high with a graft box (Hipobioto) of lemon tree (of the family Rutaceae) in each tube. The doses used were constituted by doses of N (460; 920 e 18,10 mg dm(-3)), P (50; 100 e 200 mg dm(-3)) and K (395; 790 e 1580 mg dm(-3)). The fertilization with N and K was carried out by fertirrigations and the P added to the substract of Pinus rind and vermiculite before the seeding. when the plants were 133 days after the germination they were subdivided in radicular system and air part for the determinations of the dry matter mass, height, foliar area, stem diameter and contents of nutrients. The N, K and P doses of 920 mg dm(-3), 790 mg dm(-3), 100 mg dm(-3), respectively, were enough for the suitable development of the graft box of lemon tree (of the family Rutaceae) in tubes.

Available Phosphorus Evaluated by Three Soil Tests in a Brazilian Tropical Oxisol Treated With Gypsum

Mehlich-1, resin-HCO(3), and Pi tests were used to assess available P in an acid tropical Oxisol in Brazil treated with gypsum, which has been preferred over lime to ameliorate the Al toxicity in the subsoil. The soil was incubated in the laboratory at rates up to 75 g kg(-1) of phosphogypsum (PG) containing 0.3% total P, natural gypsum, or reagent-grade gypsum, and up to 100 mg P kg(-1) as triple superphosphate (TSP) or phosphate rock (PR). In the greenhouse, two consecutive maize crops were grown on the soil treated with 50 mg P kg(-1) of TSP and PG rates up to 75 g kg(-1). The results of the incubation study showed that Mehlich-P and Pi-P increased with increasing PG rate for the treatments of TSP, PR, and control. Resin-HCO(3) underestimated available P from TSP and PR because of the reaction between resin-HCO(3) and gypsum. Mehlich-1 overestimated available P from PR compared with TSP because of an excessive dissolution of PR by the strongly acidic Mehlich-1. Pi underestimated available P from PR in the treatments of natural and reagent-grade gypsum because of Ca common-ion effect from gypsum on depressing PR dissolution. The results in terms of the effect of PG on available P are similar in both incubation and greenhouse studies. Both Mehlich-P and Pi-P correlated well with P uptake by maize, whereas resin-P did not.

Plant availability of phosphorus in four superphosphate fertilizers varying in water-insoluble phosphate compounds

There is concern that the use of lower quality phosphate rock can result in elevated amounts of Fe-Al-P water-insoluble compounds in fertilizers and, consequently, low agronomic effectiveness. Therefore, studies were conducted to evaluate the effect of some of these compounds on plant growth. Four commercial superphosphates varying in chemical composition (two single and two triple superphosphates) were selected for the study. Fertilizer impurities were collected as water-insoluble residues by washing each P source with deionized water. A modal analysis, based primarily on elemental chemical analysis and x-ray diffractometry, was used to estimate the chemical composition of each P source. Water-soluble monocalcium phosphate (MCP) and the water-leached fertilizer residues were prepared to give a range of fertilizers in terms of water-soluble phosphorus (WSP) (0-100% of the available P as MCP). The water-leached fractions, MCP, and the mixtures of MCP with water-leached fractions were applied to supply 40 mg available P kg(1) to a thermic Rhodic Kanhapludult with pH values of 5.2 +/- 0.05 (unlimed) and 6.4 +/- 0.08 (limed). Wheat (Triticum aestivum L.) grown in a greenhouse for 101 d served as the test crop. The requirement for WSP was source and pH dependent. At a soil pH of 5.2, the fertilizers required 73 to 95% WSP to reach the maximum dry-matter yield, while they required 60 to 86% WSP at pH 6.4. To reach 90% of the maximum yield, all superphosphate fertilizers required <50% WSP. These results show that it is not always necessary to have high water solubility as required by legislation in many countries.

Runoff and leachate losses of phosphorus in a sandy spodosol amended with biosolids

Florida Spodosols axe sandy, inherently low in Fe- and Al-based minerals, and sorb phosphorus (P) poorly. We evaluated runoff and leachate P losses from a typical Florida Spodosol amended with biosolids and triple superphosphate (TSP). Phosphorus losses were evaluated with traditional indoor rainfall simulations but used a double-deck box arrangement that allowed leaching and runoff to be determined simultaneously. Biosolids (Lakeland, OCUD, Milorganite, and Disney) represented contrasting values of total P, percent water-extractable p (PWEP), and percentage of solids. All P sources were surface applied at 224 kg P ha(-1), representing a soil P rate typical of N-based biosolids application. All biosolids-P sources lost less P than TSp, and leachate-P losses generally dominated. For Lakeland-amended I soil, bioavailable P (BAP) was mainly lost by runoff (81% of total BAP losses). This behavior was due to surface scaling and 1 drying after application of the slurry (31 g kg(-1) solids), material. For all other P sources, BAP losses in leachate were much,greater than in runoff, representing 94% of total BAP losses for TSP, 80% for Milorganite, 72% for Disney, and 69% for OCUD treatments. Phosphorus leaching can be extreme and represents a great concern in many coarse-textured Florida Spodosols, and other coastal plain soils with low P-sorption,capacities. The PWEP values of P sources were significantly correlared with total P and BAP losses in runoff and leachate. The PWEP of a source can serve as a good indicator of potential P loss when amended to sandy soils with low P-retention capacities.

Phosphorus overload and PTH induce aortic expression of Runx2 in experimental uraemia

Background. Vascular calcification (VC) is commonly seen in patients with chronic kidney disease (CKD). Elevated levels of phosphate and parathormone (PTH) are considered nontraditional risk factors for VC. It has been shown that, in vitro, phosphate transforms vascular smooth muscle cells (VSMCs) into calcifying cells, evidenced by upregulated expression of runt-related transcription factor 2 (Runx2), whereas PTH is protective against VC. In addition, Runx2 has been detected in calcified arteries of CKD patients. However, the in vivo effect of phosphate and PTH on Runx2 expression remains unknown. Methods. Wistar rats were submitted to parathyroidectomy, 5/6 nephrectomy (Nx) and continuous infusion of 1-34 rat PTH (at physiological or supraphysiological rates) or were sham-operated. Diets varied only in phosphate content, which was low (0.2%) or high (1.2%). Biochemical, histological, immunohistochemistry and immunofluorescence analyses were performed. Results. Nephrectomized animals receiving high-PTH infusion presented VC, regardless of the phosphate intake level. However, phosphate overload and normal PTH infusion induced phenotypic changes in VSMCs, as evidenced by upregulated aortic expression of Runx2. High-PTH infusion promoted histological changes in the expression of osteoprotegerin and type I collagen in calcified arteries. Conclusions. Phosphate, by itself is a potential pathogenic factor for VC. It is of note that phosphate overload, even without VC, was associated with overexpression of Runx2 in VSMCs. The mineral imbalance often seen in patients with CKD should be corrected.

Phosphorus kinetics in calves experimentally submitted to a trickle infection with Cooperia punctata

Ten male Holstein calves (74.3 +/- 3.2 kg LW) were used for a trial with trickle infection with Cooperia punctata to evaluate phosphorus (P) kinetics. Five calves were inoculated with 10,000 L(3) stage larvae per week during 35 days, while the other group of five calves was kept as a control. On the 29th day each calf was intravenously injected with 29.6 MBq of a (32)p solution. Blood samples were taken at 24 h periods for 7 days, after which all calves were slaughtered and worms burdens. Faeces, urine and tissue samples were taken for analysis using isotopic dilution and modeling techniques. The number of eggs per gram of faeces (EPG)was 1920 +/- 168 on 28th day and the total number of worms burdens was 11,131 +/- 1500. Infected calves showed lower feed intake and live weight gain, as well as lower P intake, absorption and retention than control calves. The P flows between body compartments were lower for blood to gastrointestinal tract (TGI), TGI to blood, blood to soft tissues, bone balance and soft tissue balance in infected calves when compared to the control. The trickle infection of C punctata affected P metabolism due to the decrease in P retained and live weight due to fall in feed intake. (C) 2009 Elsevier B.V. All rights reserved.

The role of an insulating surface layer on the relaxation time of the ionic redistribution in an electrolytic cell

We analyze the influence of a surface dielectric layer on the transient phenomena related to the ionic redistribution in an electrolytic cell submitted to a step-like external voltage. The adsorption-desorption phenomenon is taken into account in the famework of the Gouy-Chapman approximation, where the ions are assumed dimensionless. In the limit of small amplitude of the applied voltage, where the equations of the problem can be linearized, we obtain an analytical solution for the surface densities of ions, for the electrical potential and for the relaxation time for the transient phenomena. In the general case, when the linearized analysis is no longer valid, the solution of the problem is obtained numerically. The role of the thickness of the dielectric layer on the relaxation time is also discussed.

A quantum chemical study on the formation of phosphorus mononitride

The chemical mechanism of the (1)PN formation was successfully studied by using the CCSD(T)/6-311++G(3df,3pd) level of theory. The (1)NH(3) + (3)PH and (4)P + NH(3) reaction paths are not energetically favorable to form the (1)PN molecule. However, the (3)NH + (3)PH, (4)N + (3)PH(3), (4)N + (3)PH, (4)P + (3)NH, and (4)P + (2)NH(2) reaction paths to form the (1)PN molecule are only energetically favorable by taking place through specific transition states to form the (1)PN molecule. The NH(3) + (3)PH, (4)N + (1)PH(3), NH(3) + (4)P, and (4)N + (2)PH(2) reactions are spin-forbidden and the probability of hopping for these reactions was estimated to be 0 by the Landau-Zener theory. This is the first detailed study on the chemical mechanism for the (1)PN formation. (C) 2009 Elsevier B.V. All rights reserved.

Metabolismo mineral em bubalinos com ingestões de diferentes níveis de fósforo

Objetivou-se avaliar os efeitos da ingestão diária de quatro níveis de fósforo (8, 12, 15 e 18 g) sobre o metabolismo de macrominerais (P, Ca, Mg, Na, K e S), incluindo a ingestão, a concentração no rúmen, a taxa de passagem do líquido ruminal, a excreção nas fezes e a disponibilidade aparente. Utilizaram-se quatro bubalinos adultos com fístulas ruminais em delineamento quadrado latino (4 × 4) com dieta total constituída de cana-de-açúcar como volumoso (85%) e concentrado formulado com um dos níveis de fósforo. Os níveis de fósforo não ocasionaram diferença significativa na concentração mineral no rúmen de nenhum mineral estudado. A concentração média de fósforo no conteúdo ruminal foi de 0,98% na matéria seca, enquanto o teor de fósforo nas rações variou de 0,12 a 0,34%, comprovando alta reciclagem de fósforo pela saliva. Níveis crescentes de fósforo na dieta, variando de 8 a 18 g/animal/dia, não influenciam as disponibilidades de cálcio e magnésio. Com o nível de fósforo de 15 g/dia, houve melhor utilização do fósforo da dieta. A ingestão de níveis crescentes de fósforo em g/kg0,75 (X) promoveu aumento linear na excreção fecal desse mineral em g/kg0,75 (Y) e baixos valores de disponibilidade do fósforo, que pode ser estimado pela equação Y = 0,03 + 0,610X, o que indica deficiência desse elemento mineral na dieta para o metabolismo animal.

Uso de fosfatos com diferentes relações flúor: fósforo na alimentação de poedeiras semipesadas na fase de produção

Um experimento foi conduzido para verificar os efeitos de diferentes relações flúor:fósforo (F:P) na dieta sobre o desempenho e as concentrações de cálcio, fósforo, magnésio e flúor na tíbia de poedeiras comerciais semipesadas. Foram utilizadas 160 galinhas poedeiras, distribuídas em delineamento inteiramente casualizado, com quatro tratamentos (fontes de fósforo com diferentes relações flúor:fósforo - 1:40; 1:60; 1:80; 1:100) e cinco repetições de oito aves. No final do experimento, foram abatidas duas aves de cada repetição para coleta da tíbia e análise dos teores de flúor, cálcio, fósforo e magnésio. As relações flúor:fósforo não afetaram o consumo de ração, a produção de ovos, a conversão alimentar, o peso dos ovos e a gravidade específica. Entretanto, a porcentagem de casca e a espessura da casca foram menores quando a relação F:P foi de 1:100. Apesar da ausência de efeitos na produção de ovos, verificou-se redução de 7,3; 5,4 e 9,8% na produção entre as aves que receberam ração com a maior relação F:P (1:100) em comparação àquelas alimentadas com as rações com as relações de 1:40; 1:60 e 1:80, respectivamente. A deposição óssea de flúor reduziu e a de magnésio aumentou nas aves alimentadas com a ração contendo as maiores relação de F:P. As fontes de fósforo, nas relações fluor:fósforo de 1:40 a 1:80, podem ser utilizadas em dietas para poedeiras comerciais, pois não afetam o desempenho e a qualidade da casca dos ovos.

Changes in ruminal fermentation and mineral serum level in animals kept in high temperature environments

In order to evaluate the effect of environmental temperature on ruminal fermentation and on mineral levels of growing ruminants, it was used 12 male calves (initial average weight 82.9 ± 7.7 kg, 100 days of age), were employed in a randomized block design (by weight) experiment, with repeated weight measurement and two environmental temperatures: thermoneutral (24ºC) and heat-stressed (33ºC), during 38 days. The animals exposed to 33ºC presented lower dry matter ingestion, lower T3 (triiodothyronine) serum level, higher ammoniacal nitrogen (NH3-N) level in the rumen liquid, and higher rectal and body temperatures during all the experimental period when compared to the animals kept in thermoneutral environment (24ºC). The animals kept under heat stress environment (33ºC) presented higher calcium serum level, which was the highest on 31st day and the lowest on the 38th day of the experiment; phosphorus level was the lowest during all the experimental period; sodium level was lower on the 17th, 31st and 38th experimental days. Potassium and zinc levels were lower after 24 days; copper level was lower until the 24th day; magnesium level was higher until the 17th day, if compared to the ones from the animals kept in thermoneutral environment (24ºC). The heat-stressed animals presented higher levels of ammoniacal nitrogen in the ruminal liquid and a decrease in the phosphorus, sodium, potassium and zinc serum levels. These results show the necessity of changes on feed management to ruminants in temperatures over the thermal comfort limits so that performance loss is decreased.

Sobre uma degenerescência acidental nos deslocamentos químicos de RMN de 31P{¹H} em complexos difosfínicos de rutênio

The [RuCl(bipy)(dppb)(4-pic)]PF6 complex was prepared and fully characterized. The X-ray crystal structure of this complex was determined in order to make an unambiguous distinction between the two possible positions of the 4-methylpyridine ligand (4-pic) in the compound: trans to phosphorus atom or trans to nitrogen atom. The [RuCl(bipy)(dppb)(4-pic)]PF6 complex exhibits an unusual temperature-dependent accidental degeneracy of the 31P chemical shifts in its solution NMR spectrum.

Synthesis, screening for antiacetylcholinesterase activity and binding mode prediction of a new series of [3-(disubstituted-phosphate)-4,4,4-trifluoro-butyl]-carbamic acid ethyl esters

A series of nine new [3-(disubstituted-phosphate)-4,4,4-trifluoro-butyl]-carbamic acid ethyl esters (phosphate-carbamate compounds) was obtained through the reaction of (4,4,4-trifluoro-3-hydroxybut-1-yl)-carbamic acid ethyl esters with phosphorus oxychloride followed by the addition of alcohols. The products were characterized by ¹H, 13C, 31P, and 19F NMR spectroscopy, GC-MS, and elemental analysis. All the synthesized compounds were screened for acetylcholinesterase (AChE) inhibitory activity using the Ellman method. All compounds containing phosphate and carbamate pharmacophores in their structures showed enzyme inhibition, being the compound bearing the diethoxy phosphate group (2b) the most active compound. Molecular modeling studies were performed to investigate the detailed interactions between AChE active site and small-molecule inhibitor candidates, providing valuable structural insights into AChE inhibition.

Temporal variation of the phytoplankton community at short sampling intervals in the Mundaú reservoir, Northeastern Brazil

The aim of this study was to determine how abiotic factors drive the phytoplankton community in a water supply reservoir within short sampling intervals. Samples were collected at the subsurface (0.1 m) and bottom of limnetic (8 m) and littoral (2 m) zones in both the dry and rainy seasons. The following abiotic variables were analyzed: water temperature, dissolved oxygen, electrical conductivity, total dissolved solids, turbidity, pH, total nitrogen, nitrite, nitrate, total phosphorus, total dissolved phosphorus and orthophosphate. Phytoplankton biomass was determined from biovolume values. The role abiotic variables play in the dynamics of phytoplankton species was determined by means of Canonical Correspondence Analysis. Algae biomass ranged from 1.17×10(4) to 9.21×10(4) µg.L-1; cyanobacteria had biomass values ranging from 1.07×10(4) to 8.21×10(4) µg.L-1. High availability of phosphorous, nitrogen limitation, alkaline pH and thermal stability all favored cyanobacteria blooms, particularly during the dry season. Temperature, pH, total phosphorous and turbidity were key factors in characterizing the phytoplankton community between sampling times and stations. Of the species studied, Cylindrospermopsis raciborskii populations were dominant in the phytoplankton in both the dry and rainy seasons. We conclude that the phytoplankton was strongly influenced by abiotic variables, particularly in relation to seasonal distribution patterns.