Determination Of 32P Research Articles

Influx Pathways and Key Stages of Phosphorus and Potassium Transport into Grape Fruits

ABSTRACT Using radioisotope tracer determination of 32P and 86Rb and fruit stalk micro-girdling, the influx pathways and key stages of phosphorus (P) and potassium (K) transport to grape fruits were studied. After fruit stalk micro-girdling, only 5.4% of P and 7.3% of K was transported from leaves to fruits via the xylem, compared with 46.75 and 38.67% from roots via phloem. The influx of 32P and 86Rb into fruits from treated leaves varied significantly according to stage of fruit development. For 32P, the variation was in the order: first stage > third stage > fruit veraision > second stage, while for 86Rb the order was: third stage > first stage > second stage > fruit veraision stage. The above results indicated that both first and third stages of grape fruit development had the greatest requirement for P or K from leaves, and the phloem was the dominant influx pathway for their transport into fruits from leaves.

Determination of32P in urine for early estimation of the neutron exposure levelfor three victims of the JCO criticality accident

In the criticality accident which occurred on 30 September 1999at a uranium conversion facility in Tokai-mura, Japan, threeworkers were severely exposed to neutron and gamma-rayirradiation. Preliminary estimations of doses from bloodproperties and 24Na concentration in blood were 16-20,6-10 and 1-4 gamma-ray gray-equivalent(γGyEq) respectively for thethree workers. For apparent dose estimation,neutron-induced radionuclides in biological materials such asblood, hair and urine were measured. Accordingly, we detected32P in urine samples. The concentration ratios of 32Pin the urine for the three workers showed a similar tendencyto those of 24Na in blood. This result indicated that theradioactivity of 32P in urine could be used to estimatethe neutron exposure level.

Development of Microplate-radioluminography for 32P

Basic research for designing a microplate which can be applied to determination of 32P by radioluminography was carried out. It was proven that 32P can be determined by using the microplate which has plural planchets placed at intervals on a thin plate and a brass collimator that fills the gaps between the planchets. The microplate is joined with the collimator, and exposed to an imaging plate for 24 h. The detection limit of the proposed method was estimated to be 6 m Bq. The cross-talk ratio was negligibly small (0.2%).

Direct determination of32P or36Cl in tissue solubilizer solutions by Cherenkov-scintillation counting

Phosphorus-32 and chlorine-36 radioactivity was measured directly in commercially available tissue solubilizers using a liquid scintillation counter. Various wavelength-shifting compounds: β-naphthol, 4-methylumbelliferone, 7-amino-1,3-naphtalenedisulfonic acid, 2-hydroxy-3,6-naphthalenedisulfonic acid, anthranilic acid and salicylic acid were investigated to assess their suitability for the improvement of counting efficiency. Salicylic acid was selected which is fairly stable in alkaline solutions of tissue solubilizers and remarkably improves counting efficiency up to 90% for both nuclides. 0.1 g of soft tissues or blood can be solubilized with 1 cm3 of tissue solubilizer containing 2 g/dm3 of salicylic acid directly in 6 cm3 scintillation minivials. The sample channels ratio method for colour quench correction was found to be satisfactory.

Analysis of site occupancies in [32P]phosphorylated pyruvate dehydrogenase complexes by aspartyl-prolyl cleavage of tryptic phosphopeptides.

Activity of mammalian pyruvate dehydrogenase complexes from all sources so far tested is regulated by phosphorylation involving three sites. To facilitate understanding of the precise biological roles of the individual phosphorylation sites a method has now been developed, using pig heart [32P]phosphorylated complexes, which enables unambiguous measurement of their occupancies. Established methods of tryptic digestion give two peptides that contain the three phosphorylation sites: TA contains sites 1 and 2; TB contains site 3. Thus, while occupancy of site 3 may be determined unequivocally by tryptic digestion, occupancies of sites 1 and 2 cannot. The present paper shows that peptide TA may be specifically and quantitatively cleaved by formic acid at an Asp-Pro bond located between the two phosphorylation sites. Equal amounts of two new peptides each containing a different phosphorylation site (site 1 or site 2) are produced. The 32P-labelled peptides may be completely separated and quantified by high-voltage paper electrophoresis at pH 2. A combination of tryptic digestion (determination of 32P in site 3) and formic acid cleavage of peptide TA (determination of 32P in sites 1 and 2) thus enables unequivocal assignment of occupancies of individual phosphorylation sites to greater than 95% accuracy. This method has been used to show that during phosphorylation and inactivation of pig heart complexes (inactivated to between 1.5 % and 90%) greater than 98% of the observed inactivation was primarily attributable to phosphorylation of site 1; the contribution of site 2 was less than 2% if at all. Relative initial rates of phosphorylation site 1 X site 2 X site 3 were approximately 90:3:1.

Effect of the scintillator on the instability of determination of 32P and 3H + 32P in liquid scintillation spectrometer

The time course of the changes of the counting rate caused by 32P is determined in six commercially available scintillation mixtures applicable to aqueous solutions of the samples. The measurements were performed separately in the 3H- and 32P-measuring channels. Statistically significant changes were found during the first day after the sample preparation for Unisolve 100, Unisolve 1, and Aquasolve in both counting channels, and for Unisolve ELS in the 3H-channel. Minisolve and Instagel exhibited steady values during 60 and 78 h, respectively, and after that period the changes proceeded very slowly. The stability of the counting rates for Minisolve and Instagel was checked also for 3H alone and for combined 3H + 32P-labelled samples.

Determination of 32-P in vivo.

Determination of 32-P in vivo.