Phosphorus compounds measured in a rapid and simple leaf test for the assessment of the phosphorus status of subterranean clover

1984 ◽  
Vol 24 (125) ◽  
pp. 213 ◽  
Author(s):  
GCJ Irving ◽  
D Bouma
Keyword(s):  
Leaf Tissue ◽  
Rapid Test ◽  
Subterranean Clover ◽  
Exchange Chromatography ◽  
Phosphorus Compounds ◽  
Fresh Leaf ◽  
Organic Phosphates ◽  
Phosphorus Status ◽  
Colour Development ◽  
Hydrolysis Of

Experiments were done to determine what proportion of the phosphate extracted from fresh leaf tissue by five drops of 10 N H2SO4 represents inorganic tissue phosphate, and to what extent hydrolysis of organic phosphates during and after the extraction, and during the development of the blue phosphomolybdate complex, could contribute to the values obtained. The extraction is the basis of a simple and rapid test for the assessment of the phosphorus status of subterranean clover (Bouma and Dowling 1982). Extraction of leaf tissue of subterranean clover and sunflower with 0.2 M HClO4 at O�C, which was shown to extract inorganic leaf phosphorus without causing significant hydrolysis of organic phosphates, gave values not significantly different from those in H2SO4 extracts. The rate of hydrolysis of endogenous organic phosphates in tissue, extracted and left at room temperature for periods of up to 40 min. after adding H2SO4, did not differ significantly from zero. Errors due to hydrolysis during the 30 min. previously recommended for colour development are reduced to negligible proportions by reducing the time for colour development to 10 min. and by adding citric acid at this point. Anion-exchange chromatography of 10 N H2SO4 and 0.2 M HClO4 extracts confirmed the similarity of their composition and provided estimates of the various phosphate compounds present. The extraction of fresh leaf tissue with 10 N H2SO4 provides a satisfactory estimate of the endogenous inorganic phosphorus content.

Field evaluation of a leaf test for assessment of the phosphorus status of subterranean clover and for prediction of its response to phosphorus

1985 ◽  
Vol 25 (2) ◽  
pp. 331 ◽  
Author(s):  
EJ Dowling ◽  
D Bouma
Keyword(s):  
Field Experiments ◽  
Relative Yield ◽  
Leaf Tissue ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Field Evaluation ◽  
Close Relation ◽  
Critical Value ◽  
Late Winter ◽  
Phosphorus Status

A series of field experiments (5 phosphorus levels x 6 replicates) on the southern Tablelands of New South Wales was used, firstly, to confirm the suitability of a modified test for inorganic phosphorus (Pi) concentrations in fresh clover (Trifolium subterraneum) leaves as an index of the current phosphorus status of subterranean clover-based pastures; and, secondly, to evaluate the usefulness of Pi as a predictor of responses to phosphorus applications. A close relation (R2 = 0.910) was found between Pi in healthy green leaf tissue sampled in winter and field responses to phosphorus measured at the same time. The fitted curve had a critical value of 154 ppm Pi at 90% of the fitted asymptote for relative yield. Close relations were also found between total herbage yield measured over the season and Pi in leaf tissue sampled in late autumn and early winter (R2 = 0.896) and in leaves sampled in late winter and early spring (R2= 0.877). Critical values were 160 and 153 ppm Pi respectively. The relation was less close for the third sampling (seed set and flowering, R2= 0.809) and the critical value had declined to 118 ppm Pi. It is concluded that Pi determined in clover leaf samples provides a simple measure of the current phosphorus status of subterranean clover-based pasture, and of its likely response to phosphorus. A critical value of 150 ppm Pi is confirmed for assessing the current phosphorus status, and is also proposed for predictive purposes. The method described for the estimation of Pi is a further simplification of the method presented previously. It is also more rapid and achieves a saving of 80-90% in chemicals. The correlation coefficient for the straight line relationship between the two methods was 0.956 (68 observations).

scholarly journals The properties of a carboxylesterase from the peach-potato aphid, Myzus persicae (Sulz.), and its role in conferring insecticide resistance

1977 ◽  
Vol 167 (3) ◽  
pp. 675-683 ◽  
Author(s):  
Alan L. Devonshire
Keyword(s):  
Insecticide Resistance ◽  
Myzus Persicae ◽  
Order Rate Constant ◽  
Preliminary Evidence ◽  
Exchange Chromatography ◽  
Potato Aphid ◽  
First Order ◽  
Different Strains ◽  
Hydrolysis Of ◽  
Peach Potato Aphid

Carboxylesterases from different strains of Myzus persicae were examined to try to understand their contribution to insecticide resistance. Preliminary evidence that they are involved comes from the good correlation between the degree of resistance and the carboxylesterase and paraoxon-degrading activity in aphid homogenates. Furthermore the carboxylesterase associated with resistance could not be separated from the insecticide-degrading enzyme by electrophoresis or ion-exchange chromatography. Homogenates of resistant aphids hydrolysed paraoxon 60 times faster than did those of susceptible aphids, yet the purified enzymes from both sources had identical catalytic-centre activities towards this substrate and also towards naphth-1-yl acetate, the latter being hydrolysed by both 2×106 times faster than paraoxon. These observations provide evidence that the enzyme from both sources is identical, and that one enzyme hydrolyses both substrates. This was confirmed by relating the rate of paraoxon hydrolysis to the rate at which paraoxon-inhibited carboxylesterase re-activated. Both had the same first-order rate constant (0.01min−1), showing clearly that the hydrolysis of both substrates is brought about by the same enzyme. Its Km for naphth-1-yl acetate was 0.131mm, and for paraoxon 75pm. The latter very small value could not be measured directly, but was calculated from substrate-competition studies coupled with measurements of re-activation of the diethyl phosphorylated enzyme. Since the purified enzymes from resistant and susceptible aphids had the same catalytic-centre activity, the 60-fold difference between strains must be caused by different amounts of the same enzyme resulting from mutations of the regulator gene(s) rather than of the structural gene.

scholarly journals Isolation, purification and structure of exochelin MS, the extracellular siderophore from Mycobacterium smegmatis

1995 ◽  
Vol 305 (1) ◽  
pp. 187-196 ◽  
Author(s):  
G J Sharman ◽  
D H Williams ◽  
D F Ewing ◽  
C Ratledge
Keyword(s):  
Amino Acids ◽  
Mycobacterium Smegmatis ◽  
Methyl Esters ◽  
Three Dimensional ◽  
Iron Chelation ◽  
Peptide Bond ◽  
Exchange Chromatography ◽  
Peptide Bonds ◽  
Hydrolysis Of ◽  
Gallium Complex

The extracellular siderophore from Mycobacterium smegmatis, exochelin MS, was isolated from iron-deficiently grown cultures and purified to > 98% by a combination of ion-exchange chromatography and h.p.l.c. The material is unextractable into organic solvents, is basic (pI = 9.3-9.5), has a lambda max at 420 nm and a probable Ks for Fe3+ of between 10(25) and 10(30). Its structure has been determined by examination of desferri- and ferri-exochelin and its gallium complex. The methods used were electrospray-m.s. and one- and two-dimensional (NOESY, DQF-COSY and TOCSY) 1H n.m.r. The constituent amino acids were examined by chiral g.l.c analysis of N-trifluoroacetyl isopropyl and N-pentafluoropropionyl methyl esters after hydrolysis, and reductive HI hydrolysis, of the siderophore. The exochelin is a formylated pentapeptide: N-(delta-N-formyl,delta N-hydroxy-R-ornithyl) -beta-alaninyl-delta N-hydroxy-R-ornithinyl-R-allo-threoninyl-delta N-hydroxy-S-ornithine. The linkages involving the three ornithine residues are via their delta N(OH) and alpha-CO groups leaving three free alpha-NH2 groups. Although there are two peptide bonds, these involve the three R (D)-amino acids. Thus the molecule has no conventional peptide bond, and this suggests that it will be resistant to peptidase hydrolysis. The co-ordination centre with Fe3+ is hexadenate in an octahedral structure involving the three hydroxamic acid groups. Molecular modelling shows it to have similar features to other ferric trihydroxamate siderophores whose three-dimensional structures have been established. The molecule is shown to have little flexibility around the iron chelation centre, although the terminal (Orn-3) residue, which is not involved in iron binding except at its delta N atom, has more motional freedom.

scholarly journals Purification and properties of three (1→3)-β-d-glucanase isoenzymes from young leaves of barley (Hordeum vulgare)

1993 ◽  
Vol 289 (2) ◽  
pp. 453-461 ◽  
Author(s):  
M Hrmova ◽  
G B Fincher
Keyword(s):  
Hordeum Vulgare ◽  
Elevated Temperatures ◽  
Gel Filtration ◽  
Degree Of Polymerization ◽  
Exchange Chromatography ◽  
Purification And Properties ◽  
Young Leaves ◽  
Monomeric Proteins ◽  
Ph Range ◽  
Hydrolysis Of

Three (1->3)-beta-D-glucan glucanohydrolase (EC 3.2.1.39) isoenzymes GI, GII and GIII were purified from young leaves of barley (Hordeum vulgare) using (NH4)2SO4 fractional precipitation, ion-exchange chromatography, chromatofocusing and gel-filtration chromatography. The three (1->3)-beta-D-glucanases are monomeric proteins of apparent M(r)32,000 with pI values in the range 8.8-10.3. N-terminal amino-acid-sequence analyses confirmed that the three isoenzymes represent the products of separate genes. Isoenzymes GI and GII are less stable at elevated temperatures and are active over a narrower pH range than is isoenzyme GIII, which is a glycoprotein containing 20-30 mol of hexose equivalents/mol of enzyme. The preferred substrate for the enzymes is laminarin from the brown alga Laminaria digitata, an essentially linear (1->3)-beta-D-glucan with a low degree of glucosyl substitution at 0-6 and a degree of polymerization of approx. 25. The three enzymes are classified as endohydrolases, because they yield (1->3)-beta-D-oligoglucosides with degrees of polymerization of 3-8 in the initial stages of hydrolysis of laminarin. Kinetic analyses indicate apparent Km values in the range 172-208 microM, kcat. constants of 36-155 s-1 and pH optima of 4.8. Substrate specificity studies show that the three isoenzymes hydrolyse substituted (1->3)-beta-D-glucans with degrees of polymerization of 25-31 and various high-M(r), substituted and side-branched fungal (1->3;1->6)-beta-D-glucans. However, the isoenzymes differ in their rates of hydrolysis of a (1->3;1->6)-beta-D-glucan from baker's yeast and their specific activities against laminarin vary significantly. The enzymes do not hydrolyse (1->3;1->4)-beta-D-glucans, (1->6)-beta-D-glucan, CM-cellulose, insoluble (1->3)-beta-D-glucans or aryl beta-D-glycosides.

scholarly journals The dynamics of acid-soluble phosphorus compounds in the course of winter and spring wheat germination under various thermic conditions. Part II. Labile phosphorus after hydrolysis of the acid-soluble fraction

2015 ◽  
Vol 24 (2) ◽  
pp. 297-308
Author(s):  
A. Barbaro
Keyword(s):  
Low Temperature ◽  
Phosphorus Content ◽  
Soluble Fraction ◽  
Phosphorus Compounds ◽  
Labile Phosphorus ◽  
Soluble Phosphorus ◽  
Germination Temperature ◽  
Wheat Germination ◽  
Labile P ◽  
Hydrolysis Of

The changes in labile phosphorus compounds content during germination of wheat were investigated. These compounds were determined in acid-soluble germ extracts separated into fractions according to the solubility of their barium salts. Low germination temperature was found to raise the labile phosphorus content in the fraction of insoluble barium salts. If we assume that labile P of this fraction consisted mainly of adenosinedi- and triphosphates, it would seem that the rise, in the ATP and ADP level under the influence of low temperature may be essential for initiating flowering in winter varieties.

scholarly journals Persistence of methylated bases in ribonucleic acid of syrian golden hamster liver after administration of dimethylnitrosamine

1979 ◽  
Vol 177 (3) ◽  
pp. 967-973 ◽  
Author(s):  
G P Margison ◽  
J M Margison ◽  
R Montesano
Keyword(s):  
Ribosomal Rna ◽  
Golden Hamster ◽  
Excision Repair ◽  
Experimental System ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Syrian Golden Hamster ◽  
Low Doses ◽  
Enzymic Hydrolysis ◽  
Hydrolysis Of

1. Syrian golden hamster liver ribosomal RNA was isolated up to 96 h after administration of [14C]dimethylnitrosamine at 25 mg/kg or 2.5 mg/kg body weight. 2. The chemical alkyation products, 7-methylguanine, 3-methylcytosine, O6-methylguanosine and 1-methyladenosine, were measured after acidic or enzymic hydrolysis of the RNA to bases or mononucleosides followed by ion-exchange chromatography. 3. Between 7 and 96 h, the relative amounts of alkylation products did not change with time even though the absolute amounts fell by approx. 80% and 51% after the high and low doses respectively. 4. The results suggest that base specific excision repair does not exist for RNA alkylation products in this experimental system.

Analysis of O2′-Methylnucleoside 5′-Phosphates in Snake Venom Hydrolysates of RNA: Identification of O2′-Methyl-5-Carboxymethyluridine as a Constituent of Yeast Transfer RNA

1975 ◽  
Vol 53 (7) ◽  
pp. 735-746 ◽  
Author(s):  
M. W. Gray
Keyword(s):  
Snake Venom ◽  
Deae Cellulose ◽  
Anion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Assay Method ◽  
Blocking Group ◽  
Wheat Embryo ◽  
Yeast Trna ◽  
Snake Venom Phosphodiesterase ◽  
Hydrolysis Of

Snake venom phosphodiesterase liberates the O2′-methylnucleoside (Nm) constituents of RNA as the corresponding 5′-nucleotides (pNm), which, in contrast to normal 5′-nucleotides (pN), are resistant to dephosphorylation by venom 5′-nucleotidase. This property provides the basis of a convenient and highly reproducible quantitative assay for Nm residues in RNA. The assay method involves: (1) hydrolysis of RNA with whole or partially-purified snake venom; (2) isolation of the pNm derivatives, as a group, by anion-exchange chromatography on DEAE-cellulose; (3) resolution of the individual pNm compounds by two-dimensional paper chromatography; (4) identification and quantitative measurement of pNm derivatives by ultraviolet absorption spectrophotometry. Using this procedure, the molar proportions of the Nm constituents of wheat embryo, yeast, and Escherichia coli tRNA have been determined. The close correspondence between the values measured by venom hydrolysis and those obtained by analysis of alkali-stable dinucleotide (Nm-Np) sequences attests to the validity of the venom assay, and further indicates that alkali-stable sequences larger than dinucleotides are not present in significant amounts in the tRNA of the above three organisms.During the present investigation, several ultraviolet-absorbing components, not immediately identifiable as ribose-methylated nucleotides, were isolated along with the expected O2′-methylnucleoside 5′-phosphates. Preliminary characterization of one of these compounds suggests that it is a derivative of a novel nucleoside, O2′-methyl-5-carboxymethyluridine (cm5Um). Venom hydrolysis of yeast tRNA liberates the 5′-nucleotide of cm5Um in the form of a carboxyl-blocked derivative (pU-2). During alkaline hydrolysis of yeast tRNA, the blocking group in U-2 is labilized and cm5Um is released as part of an alkali-stable dinucleotide, cm5Um-Ap. The proportion of pU-2 in venom hydrolysates of yeast tRNA (0.02 mol%, the same as the content of cm5Um-Ap in alkaline hydrolysates) suggests that O2′-methyl-5-carboxymethyluridine may be confined to a single isoaccepting species of tRNA in yeast.In an allied study, reinvestigation of the alkali-stable dinucleotide sequences of baker's yeast tRNA has confirmed previous results concerning the sequence distribution of O2′-methylribose in yeast tRNA (Gray, M. W. &Lane, B. G. (1967) Biochim. Biophys. Acta 134, 243–257).

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