14C Compounds Research Articles

Effects of various physiochemical factors on microbial activity in peatlands: aerobic biodegradative processes

The quantitative relationships between the biodegradative activities of peatland microorganisms and several relevant physiochemical environmental parameters were examined. Temperature decrease from 30 to 4 °C was found to slow, but not eliminate, microbial activity (mineralization of 14C compounds to 14CO2). Microbial activity generally was higher at ambient peatland pH's (pH 3–4.5), rather than at more neutral pH's, in the media used. Low oxygen tension significantly decreased the metabolic activities of peatland surface-inhabiting microbes. Individual pure cultures isolated from peatlands exhibited different responses to decreasing pH, oxygen tension, and temperature; demonstrating great physiological diversity among peatland microbes. Concentrations of nutrients such as nitrogen and phosphorus appear not to limit severely most microbial activities in peatland habitats.

Effects of Soil Mixing and Flooding on the Fate and Metabolism of 14C-Fonofos and 14C Parathion in Open and Closed Agricultural Microcosms

The effects of soil surface application and soil incorporation (“tillage”) of 14C-fonofos and 14C-parathion on the metabolic fate of the insecticides in soils and their translocation into oat leaves were investigated in the laboratory, using both open and closed microcosms. The effects of flooding of 14C insecticide-treated soils were also studied. The insecticides were least persistent after their application to the soil surface, whereas mixing the insecticides with the soil increased the persistence of fonofos and parathion by factors of 2 and 5.3. respectively. Most of the organic solvent-soluble radiocarbon in 14C insecticide-treated soils was recovered as the undegraded parent compound, more so with fonofos than with parathion. In oat leaves from fonofos-treated soils, most of the organic soluble 14C recovered (1% of less of the soil-applied radiocarbon) was associated with the non-insecticidal fonofos metabolite methyl phenyl sulfone; in leaves from parathion-treated soil, > 90% of the organic soluble 14C (0.1 % of the soil-applied dose) was associated with parathion. In experiments with closed systems, the amounts of 14CO2 produced from soil-applied 14C-parathion were 30% of the insecticide applied to the soil surface, 23% of that mixed with the soil, and only 0.9% of that mixed with the soil and kept under flooded conditions. With fonofos-treated soils, less 14CO2 was produced, but the general trend was the same as that observed with parathion. Binding of 14C compounds to soils increased after the insecticides had been mixed with the soil and, in particular, after soil flooding when 72% of the soil-applied 14C-parathion was unextractable.

The utilization of exogenous taurine for the conjugation of xenobiotic acids in the ferret.

Although the occurrence of the taurine conjugation mechanism for various xenobiotic acids is well established, nothing is known of the source of the taurine used for this conjugation. [14C]Taurine was administered alone and in combination with 2-naphthylacetic acid or clofibric acid (both of which are known to form taurine conjugates) to to ferrets, and the 0--24 h urine collected. Of the dose of [14C]taurine, 26% was recovered in the urine in 24 h and the only 14C-containing material present was unchanged taurine. When either 2-naphthylacetic acid or clofibric acid was co-administered with [14C]taurine, 21 and 17%, respectively, of the 14C dose was recovered in the 0--24 h urine. In both cases, two 14C compounds were present--unchanged taurine (minor) and the taurine conjugate of the acid in question (major). Comparison of these results with those previously obtained with 14C-labelled 2-naphthylacetic and clofibric acids, shows that the taurine used for their conjugation is derived from a pool freely accessible to exogenous taurine. The results are discussed in terms of the availability for metabolic utilization of taurine in the animal body, and of the use of co-administration of [14C]taurine with a xenobiotic acid for the identification of taurine conjugates.

Effects of phosphorus and potassium deficiency treatment on roots secretion of wheat and rice seedlings

Abstract Firstly, the secretion of sugars, protein and acid phosphatase from wheat and rice roots into surrounding medium under conditions of P and K deficiency stresses were studied. Secondly, Sephadex elution patterns of wheat root exudates labeled with 14C under N, P and K deficiency treatments were compared. P deficiency treatment induced acid phosphatase activity in medium, in spite of the decrease in the secretion of total sugars and pro tein from roots into medium, whereas no such increase was observed in K deficiency stress. Secretion of high molecular fraction of 14C compounds from roots was accelerated by P deficiency stress, probably being associated with the presence of phosphatase activity in the medium. Activity of acid phosphatase secreted from P-deficient roots corresponded to nearly one half of the rate of P absorption by normal plant.

Accumulation of 14C Labeled Benzene and Related Compounds in the Rotifer Brachionus plicatilis from Seawater

Rotifers were exposed to (1) a single dose of 14C labeled benzene on day 1 with initial concentrations of benzene at 0.1 and 1.0 μL/L declining over time and (2) a chronic exposure of 0.1 and 1.0 μL/L daily for 9 d. Both conditions resulted in rotifers accumulating 1000 to 10 000 times the 14C activity detected in the seawater. These concentrations were maintained in the rotifers for 8 and 11 d, respectively, and remained high even after exposure was terminated. Analysis of 14C activity from 14C labeled benzene detected in the water revealed its source to be phenolic compounds, compounds with a potentially higher toxicity than benzene. The water maintained a low level of 14C compounds throughout the experiments. Rotifers accumulated high quantities and retained most of the acquired 14C compounds after 2 d in clean water.Key words: benzene, rotifer, zooplankton, biomagnification

Absence of Binding of MDP, a Synthetic Immunoadjuvant, to Anti-Peptidoglycan Antibodies

The binding of the synthetic immunoadjuvant N-acetyl-muramyl-L-alanyl-D-isoglutamine (MDP, for muramyl dipeptide) to human and rabbit sera containing peptidoglycan (PG) antibodies was investigated. Studies were performed by employing the corresponding 14C or 125I-labeled compounds in Farr-type binding and inhibition assays. Whereas MDP did not react with naturally occurring or experimentally induced PG-antibodies, the analog of MDP MDP-L-Lys-D-Ala did bind to hyperimmune rabbit anti-PG sera, but not to the human sera tested. These studies indicate that the radioimmunoassays employed basically are applicable for the selection of nonimmumogenic MDP analogs possessing immunoadjuvant activity.

Urinary Riboflavin Metabolites in the Rat

Male rats were fed a riboflavin-deficient diet for 25 days and then fed [2-14C]riboflavin to replete their riboflavin pool(s). During a second depletion period, urine and feces were collected and 14C excretion monitored. The urine was chromatographed on R-15 resorcinol resin and 14C was measured in all fractions. The 14C compounds in the individual fractions were shown to be different by thin layer chromatography. The amount of 14C recovered as riboflavin increased after acid hydrolysis of the urine indicating the presence of riboflavin in conjugated forms. All R-15 fractions were found to support growth in a microbiological (L. casei) assay for riboflavin. This suggested that other derivatives, in addition to riboflavin and flavin nucleotides, are biologically active. However, the conjugated compounds were apparently less active, since acid hydrolysis of the urine enhanced its growth-promoting ability of L. casei. One 14C metabolite was identified as urea, thus providing evidence for degradation of the riboflavin molecule. This study has shown that the metabolic fates of riboflavin in the rat include conjugation and extensive degradation.

Release of Phospholipids from Complement-Mediated Lesions on the Surface Structure of Escherichia Coli

When varying numbers of sensitized, 14C-labeled bacteria were treated with a certain amount of complement, in a fixed reaction volume, 14C compounds were liberated into the surrounding medium in proportion to the number of the bacteria, whereas the amount of the phospholipids liberated was constant regardless of the number of the bacteria even in the range of relative excess of complement. Since it is conceivable that a certain amount of complement might form a fixed number of lesions on the surface of all the sensitized bacteria, the amount of the liberated phospholipids seems to be proportional to the number of complement lesions. The 14C-materials released from complement-attacked bacteria were analyzed by isopycnic sucrose density gradient ultracentrifugation and they were mainly free phospholipids and other smaller molecules. A small amount of the smaller membrane proteins were also released as revealed by acid and SDS-polyacrylamide gel electrophoresis. These results suggest that the release of phospholipids is due to the displacement of membrane lipids by the complexes of the late acting complement components during their insertion into the membrane lipid bilayer.

A New Laboratory Method Used for Investigating the Uptake, Translocation and Metabolism of Bark Banded Morphactin by Trees

AbstractCut twigs of Monterey pine(Pinus radiata D.Don) were banded with a 14C labelled morphactin formulation and the lower half of the twig placed in a Scholander type pressure bomb. Water was pumped through the twig from a reservoir inside the bomb and exudate collected from the protruding end of the twig. Using this method it was possible to determine that the slowest step in the translocation of morphactin was the passage across the outer layer of bark. Subsequent passage through the twig was not affected by girdling the bark suggesting that morphactin was translocated upwards via the xylem. The 14C compound in the exudate from live twigs differed from morphactin and was tentatively identified as the carboxylic acid derivative of the morphactin ester.The cut twig system facilitated studies on the uptake, metabolism and translocation of morphactin and should prove useful for studying the uptake and fate of other chemicals considered for bark application to trees.

Studies on plant growth‐regulating substances XLV. Phenoxyacetaldehyde derivatives

SUMMARYPlant growth‐regulating activity in a series of phenoxyacetaldehyde derivatives has been assessed in a number of tests. Metabolic experiments using labelled 14C compounds are discussed.

Sources of Carbon Skeleton of Alanine Released from Skeletal Muscle

The formation of alanine, glutamate, and aspartate from muscle was studied in the isolated perfused hindquarter of rats fasted for 48 h. Tracer doses of (14C) compounds with high specific activity were tested as precursors for the amino acids. Total amounts and radioactivities of the tested amino acids were determined. Alanine was produced more efficiently than glutamate and aspartate even if no exogenous substrate was offered. (14C) Pyruvate was most efficient as precursor of labeled alanine. However, labeled leucine, propionic acid, valine and fumaric acid also produced labeled alanine efficiently. The efficiency as precursor for labeled alanine seemed to be related to the ability to label intermediates in the citric acid cycle in the perfused muscle. From the relation between the ability to label alanine in the perfusion medium and lactate and succinate in the muscle it is suggested that pyruvate may be produced intramitochondrially and is efficiently transaminated to alanine in this compartment.

Liquid scintillation counting of aqueous samples using Triton-containing scintillants

Markedly unstable count rates were observed using a toluene-Triton (2:1, v v ) scintillant during counting of water-soluble radioactive compounds when < 5% ( v v ) water was present, because of the separation of phases. Efficiency correction in these instances could not be made by using 3H 2O as internal standard, because under the same conditions count rates with tritiated water were stable. Increasing water to ≥6% stabilized the count rates. With toluene-Triton (2:1, v v ) scintillant, the water level should preferably be maintained between either 6 and 12 or 18 and 24% for 14C- and 3H-labeled compounds for counting at 6°C or at ambient temperature (but only between 6 and 12% for 3H counting at room temperature). With a “Tritosol” ( Anal. Biochem. 63, 555 (1975) modified to contain 35 ml of ethylene glycol, 140 ml of ethanol, 250 ml of Triton X-100, 575 ml of xylene, 3 g of PPO, and ±200 mg of POPOP, water levels of up to 23% were acceptable for 14C and 3H for counting at room temperature or at 6°C. Within these limitations, with the toluene-Triton or with the modified Tritosol as scintillant, both polar and apolar radioactive compounds exhibited similar efficiencies and gave quench-correction curves, based on the external standard ratio, that were linear for both 14C and 3H-labeled compounds.

Tissue distribution of technetium-99m and carbon-14 labeled N-(2,6-dimethylphenylcarbamoylmethyl)iminodiacetic acid.

The synthesis, radiochemical labeling, and tissue distribution characteristics of N-(2,6-dimethylphenylcarbamoylmethyl)iminodiacetic acid are described. The radiopharmaceutical prepared by labeling with 99mTc was rapidly eliminated through the hepato-biliary system of mice. Parent 14C compound was eliminated primarily through the kidney. The 99mTc ion appears to have a greater influence than the organic carrier molecule on the distribution of the radiopharmaceutical.

Study of the biosynthesis of phleic acids, polyunsaturated fatty acids synthesised by Mycobacterium phlei (author's transl)

Because of their structures, phleic acids (general formula: CH3-(CH2)m-(CH=CH-CH2-CH2)n-CO2H; main component: m = 14, n = 5) cannot be synthesized by the same kinds of enzymatic systems as other natural polyunsaturated fatty acids. By using specifically labelled 14C compounds, we have tested the ability of different molecules to be incorporated in the phleate skeletons by Mycobacterium phlei. The localisation of radioactive carbon atoms has been studied by chemical degradation of labelled phleates, isolation and purification of the degradation products, and determination of their specific radioactivity. When M. phlei cells are incubated with labelled acetate, the unsaturated and saturated parts of the molecules of phleic acids are unequally labelled. The radioactivity of succinate monoester on the one hand and fatty acids (mixture of myristic and palmitic acids) on the other hand, measured after oxidative degradation of phleate esters, shows a constant ratio under definite conditions. Whether [1-14C]acetate or [2-14C]acetate is used for incubation, the same ratio is observed. Therefore acetate is the precursor of the unsaturated part as well as of the saturated part of the phleate molecules. By using labelled fatty acid esters, it has been found that palmitic acid is the precursor of phleates with m = 14, while myristic acid is the precursor of phleates with m = 12. Stearic and eicosanoic acids are not incorporated without degradation. The hypothesis of a condensation of a saturated fatty acid with a preformed polyunsaturated molecule was examined. Search for such a molecule in the lipids of M. phlei gives negative results. Pentaunsaturated phleate arising from palmitate is more abundant than pentaunsaturated phleate arising from myristate, while the reverse is true for hexaunsaturated phleates. These observations make very unlikely such an hypothesis. An elongation process fits well with the observed facts provided that this process involves elongation by two acetate units simultaneously, making elongation by four carbon atoms at a time. Such a requirement would be easily satisfied if two molecules of acetate are condensed together before their utilization in the elongation process. In such a hypothetical process, crotonate would be the most probable substrate of the elongation reaction.

ACTIONS OF NEUROHUMORAL AGENTS AND CEREBRAL METABOLITES ON OUTPUT OF ADENINE DERIVATIVES FROM SUPERFUSED TISSUES OF THE BRAIN

—Adenine nucleotides of guinea-pig neocortical tissues were labelled by prior incubation with [14C]adenine and excess of adenine was then removed by superfusion with precursor-free media. During continued superfusion labelled adenine derivatives were released at a stable rate of about 0·05 per cent of the tissue 14C/min and this rate was increased about five-fold by electrical stimulation. Various compounds, including some known to increase the cyclic AMP content of cerebral tissues, were examined for action on the release of [14C]adenine derivatives from the tissue and also on the rates of lactate production by the tissue, both before and during electrical excitation. The tissue content of adenine nucleotides following exposure of the tissue to these compounds was also determined. Noradrenaline, γ-aminobutyrate and acetylcholine together with carbamoylcholine at the concentrations examined were without effect on the release of 14C compounds from the tissue. Also, noradrenaline and γ-aminobutyrate caused no alteration in lactate production but brought about some decrease in the adenylate energy charge of the tissue. Histamine, 100 μm, brought about a small but consistent increase (35 per cent) both in release of 14C-compounds and lactate output, while reducing the adenylate energy charge of the tissues. l-Glutamate at 5 mm decreased the tissue adenylate energy charge to a greater extent than did histamine; it increased the release of 14C-compounds seven to eight-fold and similarly increased the tissues' rates of lactate production. Lower concentrations of glutamate had smaller effects. In those cerebral tissues whose cyclic AMP content is increased by l-glutamate, the increase is probably brought about by intermediation of released adenosine.

ACTIONS OF NEUROHUMORAL AGENTS AND CEREBRAL METABOLITES ON OUTPUT OF ADENINE DERIVATIVES FROM SUPERFUSED TISSUES OF THE BRAIN

Abstract—Adenine nucleotides of guinea‐pig neocortical tissues were labelled by prior incubation with [14C]adenine and excess of adenine was then removed by superfusion with precursor‐free media. During continued superfusion labelled adenine derivatives were released at a stable rate of about 0·05 per cent of the tissue 14C/min and this rate was increased about five‐fold by electrical stimulation. Various compounds, including some known to increase the cyclic AMP content of cerebral tissues, were examined for action on the release of [14C]adenine derivatives from the tissue and also on the rates of lactate production by the tissue, both before and during electrical excitation. The tissue content of adenine nucleotides following exposure of the tissue to these compounds was also determined.Noradrenaline, γ‐aminobutyrate and acetylcholine together with carbamoylcholine at the concentrations examined were without effect on the release of 14C compounds from the tissue. Also, noradrenaline and γ‐aminobutyrate caused no alteration in lactate production but brought about some decrease in the adenylate energy charge of the tissue. Histamine, 100 μm, brought about a small but consistent increase (35 per cent) both in release of 14C‐compounds and lactate output, while reducing the adenylate energy charge of the tissues. l‐Glutamate at 5 mm decreased the tissue adenylate energy charge to a greater extent than did histamine; it increased the release of 14C‐compounds seven to eight‐fold and similarly increased the tissues' rates of lactate production. Lower concentrations of glutamate had smaller effects. In those cerebral tissues whose cyclic AMP content is increased by l‐glutamate, the increase is probably brought about by intermediation of released adenosine.

The effect of dry conditions on subsequent leakage and rotting of fungal sclerotia

Dried sclerotia of Sclerotium delphinii rotted in moist soil whereas those of Sclerotium cepivorum. Botrytis cinerea and Botrytis tulipae did not. A number of fungi invaded dried sclerotia of S. delphinii in soil, the principal coloniser found in the first sampling being Trichodermu hamatum. Leakage of 14C compounds from dried labelled sclerotia placed in water was rapid and was little affected by variation in leakage temperature from 1 to 25°C or by prolonging the drying period beyond a day. Leakage from dried sclerotia which were allowed to imbibe water through a small part of their surface was much reduced. Sclerotia which were redried after leakage leaked again when returned to water but with all four fungi the first of three leakage cycles gave the highest 14C levels. Loss in dry weight in the first leakage cycle was greater with S. delphinii than with the other three fungi and this may be related to the poor survival of dried sclerotia of S. delphinii in moist soil. Substances lost during leakage appear to originate from within sclerotial hyphae rather than from the hyphal free space.

14C‐Studies on Apple Trees. V. Translocation of Labelled Compounds from Leaves to Fruit and their Conversion within the Fruit

AbstractFollowing application of 14CO2 to fruit spur leaves, the majority of the 14C absorbed is transfered to the fruit on the same spur, and the total content of 14C within the leaf‐fruit system as a whole remains virtually constant with time. The considerable reduction in activity in the leaves is accounted for mainly by a decrease in the amount of 14C‐sorbitol, although relatively speaking the decrease in 14C‐sucrose is also considerable. The major part of the activity of the sugar fraction in the conducting tissues between blade and fruit (petiol, spur) is found in sorbitol. Immediately following uptake of 14C yia the leaves a large part of the activity of the sugar fraction in the fruit is found in sorbitol; but this activity is rapidly reduced, accompanied by an increase in sucrose activity, and over longer periods of time increases in particular in glucose and fruclose activity, and in that of methanol insoluble compounds. The changes in activity distribution in the fruit vary with the variety of fruit and the dates within the growing season.By injecting labelled sorbitol directly into the fruit sorbitol is converted into sucrose, glucose and fructose, while injection of labelled sucrose, glucose and fructose has yielded proof of interconversions between these compounds but no measurable amounts of surbitol. After application of 14CO2 directly to the outer skin of the fruit considerably less of the activity is found in sorbitol than is the case in leaves following exposure to 14CO2.A minor, but significant, translocation of 14C away from the fruit was found to take place following the application of labelled 14C compounds to the fruit.The smallness of the respiratory loss of 14C in the leaf‐fruit system is discussed. It is concluded that in apple trees considerable translocation occurs in the form of sorbitol which in the fruits rapidly converted into other compounds.

Carbon-14 Assay After Parr Peroxide Bomb Fusion

Abstract A method has been developed for converting organic 14C compounds to 14C carbon dioxide and subsequent quantitation by liquid scintillation counting. The sample is converted to sodium carbonate in a Parr bomb. Carbon dioxide is liberated from the fused salt, absorbed in an organic base, and incorporated in a liquid scintillation “cocktail” for radioassay. Some advantages over existing methods in current use are given.

Plant Uptake of 14C‐Diuron in Modified Soil

AbstractSoil pH, temperature, organic matter, and clay affected the amount of 3‐(3,4‐dichlorophenyl)‐l,l‐dimethylurea (diuron) and its metabolites in the roots and shoots of 14‐day‐old oat seedlings grown in a modified Lakeland sandy loam soil. An increase in soil pH resulted in greater amounts of diuron in the shoots. To a lesser extent, increased soil organic matter and reduced soil temperature also influenced herbicide content of shoots. In contrast, herbicide content of roots was independent of pH, organic matter, or temperature modifications. The compounds actually measured in the shoots were identified as the parent diuron molecule and the monomethyl derivative 3‐(3,4‐dichlorophenyl)‐l‐methylurea. The identities were confirmed by co‐chromatography with authentic materials in comparison to 14C compounds found in the shoots.