scholarly journals Effects of specific dietary sugars on the incorporation of 13C label from dietary glucose into neutral sugars of rat intestine and serum glycoproteins

1995 ◽  
Vol 73 (3) ◽  
pp. 443-454 ◽  
Author(s):  
Corinne Rambal ◽  
Christiane Pachiaudi ◽  
Sylvie Normand ◽  
Jean-Paul Riou ◽  
Pierre Louisot ◽  
...  
Keyword(s):  
Sugar Metabolism ◽  
Isotope Ratio Mass Spectrometry ◽  
Pulse Labelling ◽  
Glycoprotein Synthesis ◽  
Serum Glycoprotein ◽  
Neutral Sugars ◽  
Labelling Experiment ◽  
13C Label ◽  
Dietary Sugars ◽  
Continuous Labelling

Although theoretically all glycoprotein sugars can be derived from glucose, it may be hypothesized that specific dietary sugars could be preferential substrates for glycoprotein synthesis. To test this hypothesis, groups of rats received either continuously (continuous-labelling experiment) or for a single nutritional period (pulse-labelling experiment) a 13C-rich diet containing either maize starch or artificially labelled [13C]glucose. Some groups of rats were also provided during a single nutritional period with low amounts (20–200 mg/animal) of low-13C dietary sugars (mannose, galactose, fucose or fructose). If specific dietary sugars were preferentially incorporated into glycoproteins instead nf glucose-derived labelled sugars, a decrease would be expected in the intestinal or serum glycoprotein-sugar 13C enrichment monitored by gas chromatography-isotope-ratio mass spectrometry (GC-IRMS). Contrary to this hypothesis the results showed no significant decrease with any of the specific dietary sugars. Furthermore, with dietary low-13C mannose or galactose, a significant increase in 13C enrichment of glycoprotein-sugars was observed compared with some other nutritional groups. Moreover, in the pulse-labelling experiment, dietary mannose and galactose induced similar patterns of 13C enrichment in intestinal and serum glycoprotein-sugars. Therefore, although specific dietary sugars do not appear to be preferential substrates for glycosylation under conditions and doses relevant to current concepts of nutrition, regulatory roles of some specific dietary sugars in relation to glycoprotein-sugar metabolism might be hypothesized. These findings could lead to similar studies using stable-isotope methodology in man which could have practical consequences, especially in parenteral nutrition where glucose is the only sugar provided to the metabolism.

scholarly journals Microbial carbon recycling: an underestimated process controlling soil carbon dynamics – Part 2: A C<sub>3</sub>-C<sub>4</sub> vegetation change field labelling experiment

2015 ◽  
Vol 12 (21) ◽  
pp. 6291-6299 ◽  
Author(s):  
A. Basler ◽  
M. Dippold ◽  
M. Helfrich ◽  
J. Dyckmans
Keyword(s):  
Organic Matter ◽  
Particulate Organic Matter ◽  
Vegetation Change ◽  
Isotope Ratio Mass Spectrometry ◽  
Isotopic Signature ◽  
Total Carbon ◽  
Bulk Soil ◽  
Residence Times ◽  
Soil Matrix ◽  
Labelling Experiment

Abstract. The mean residence times (MRT) of different compound classes of soil organic matter (SOM) do not match their inherent recalcitrance to decomposition. One reason for this is the stabilization within the soil matrix, but recycling, i.e. the reuse of "old" organic material to form new biomass may also play a role as it uncouples the residence times of organic matter from the lifetime of discrete molecules in soil. We analysed soil sugar dynamics in a natural 30-year old labelling experiment after a wheat-maize vegetation change to determine the extent of recycling and stabilization by assessing differences in turnover dynamics between plant and microbial-derived sugars: while plant-derived sugars are only affected by stabilization processes, microbial sugars may be subject to both, stabilization and recycling. To disentangle the dynamics of soil sugars, we separated different density fractions (free particulate organic matter (fPOM), light occluded particulate organic matter (≤ 1.6 g cm−3; oPOM1.6), dense occluded particulate organic matter (≤ 2 g cm−3; oPOM2) and mineral-associated organic matter (> 2 g cm−3; mineral)) of a silty loam under long-term wheat and maize cultivation. The isotopic signature of neutral sugars was measured by high pressure liquid chromatography coupled to isotope ratio mass spectrometry (HPLC/IRMS), after hydrolysis with 4 M Trifluoroacetic acid. While apparent MRT of sugars were comparable to total organic carbon in the bulk soil and mineral fraction, the apparent MRT of sugar carbon in the oPOM fractions were considerably lower than those of the total carbon of these fractions. This indicates that oPOM formation was fuelled by microbial activity feeding on new plant input. In the bulk soil, MRT of the mainly plant-derived xylose were significantly lower than those of mainly microbial-derived sugars like galactose, rhamnose, fucose, indicating that recycling of organic matter is an important factor regulating organic matter dynamics in soil.

scholarly journals Serum glycoprotein synthesis after partial hepatectomy in the rat

1976 ◽  
Vol 158 (1) ◽  
pp. 153-155 ◽  
Author(s):  
F Serafini-Cessi
Keyword(s):  
Partial Hepatectomy ◽  
Specific Radioactivity ◽  
Glycoprotein Synthesis ◽  
Early Stages ◽  
Serum Glycoprotein

The incorporation in vivo of D-[1-14C]glucosamine into serum glycoproteins and proteins of liver microsomal fractions shows a decrease in the early stages (24h) after partial hepatectomy compared with sham-operated animals; 72h after partial hepatectomy the specific radioactivity of hexosamines bound to liver microsomal fractions reaches the same value as for sham-operated animals.

The dynamics of neutral sugars in the rhizosphere of wheat. An approach by13C pulse-labelling and GC/C/IRMS

2004 ◽  
Vol 267 (1-2) ◽  
pp. 243-253 ◽  
Author(s):  
D. Derrien ◽  
C. Marol ◽  
J. Balesdent
Keyword(s):  
Pulse Labelling ◽  
Neutral Sugars

scholarly journals Observations on the biosynthesis of phytoterpenoid quinone and chromanol nuclei

1967 ◽  
Vol 105 (1) ◽  
pp. 145-154 ◽  
Author(s):  
G R Whistance ◽  
D R Threlfall ◽  
T W Goodwin
Keyword(s):  
Rhodospirillum Rubrum ◽  
Shikimic Acid ◽  
French Bean ◽  
Side Chain ◽  
Pulse Labelling ◽  
Coumaric Acid ◽  
Ochromonas Danica ◽  
Maize Roots ◽  
Labelling Experiment ◽  
Acid Pathway

1. p-Hydroxy[U−14C]benzoic acid, except for loss of the carboxyl group, is effectively incorporated into the nucleus of ubiquinone and an unidentified prenylphenol by maize roots, maize shoots, french-bean leaves, french-bean cotyledons and Ochromonas danica. Plastoquinone, α-tocopherol, γ-tocopherol and α-tocopherolquinone are all unlabelled from this substrate. The high radioactivity of the prenylphenol and its behaviour in a pulse-labelling experiment with maize shoots suggested that it may be a ubiquinone precursor. 2. Members of the 2-polyprenylphenol and 6-methoxy-2-polyprenylphenol series, compounds that are known ubiquinone precursors in Rhodospirillum rubrum, could not be detected in maize tissues, but possibly they may occur as their glycosides. 3. [G−14C]Shikimic acid is incorporated into the nuclei of phylloquinone, plastoquinone, α-tocopherolquinone, γ-tocopherol, α-tocopherol and ubiquinone in maize shoots, showing that in plant tissues the nuclei of these compounds arise via the shikimic acid pathway of aromatic biosynthesis. 4. l-[U−14C]Phenylalanine and l-[U−14C]tyrosine are incorporated into plastoquinone, γ-tocopherol, α-tocopherolquinone and ubiquinone. α-Tocopherol, which is absent from shoots incubated with l-[U−14C]tyrosine, is also labelled from l-[U−14C]phenylalanine. Degradation studies showed that there is little 14C radioactivity in the terpenoid portions of the molecules and from this it is concluded that the aromatic portions of these amino acids are giving rise to the quinone and chromanol nuclei. 5. It is proposed that in maize the nucleus of ubiquinone can be formed from either phenylalanine or tyrosine by a pathway involving p-coumaric acid and p-hydroxybenzoic acid. Plastoquinone, tocopherols and tocopherolquinones are formed from tyrosine by some pathway in which the aromatic ring and C-3 of the side chain of this amino acid gives rise to the nucleus and one methyl substituent respectively of these compounds.

scholarly journals Carbon transfer, partitioning and residence time in the plant-soil system: a comparison of two <sup>13</sup>CO<sub>2</sub> labelling techniques

2013 ◽  
Vol 10 (10) ◽  
pp. 16237-16267
Author(s):  
M. S. Studer ◽  
R. T. W. Siegwolf ◽  
S. Abiven
Keyword(s):  
Residence Time ◽  
Logistic Function ◽  
Pulse Labelling ◽  
Transfer Velocity ◽  
Plant Soil ◽  
Soil Systems ◽  
C Dynamics ◽  
C Cycling ◽  
C Partitioning ◽  
Continuous Labelling

Abstract. Various 13CO2 labelling approaches exist to trace carbon (C) dynamics in plant-soil systems. However, it is not clear if the different approaches yield the same results. Moreover, there is no consistent way of data analysis to date. In this study we compare with the same experimental setup the two main techniques: the pulse and the continuous labelling. We evaluate how these techniques perform to estimate the C transfer velocity, the C partitioning along time and the C residence time in different plant-soil compartments. We used identical plant-soil systems (Populus deltoides x nigra, Cambisol soil) to compare the pulse labelling approach (exposure to 99 atom% 13CO2 for three hours, traced for eight days) with a continuous labelling (exposure to 10 atom% 13CO2, traced for 14 days). The experiments were conducted in climate chambers under controlled environmental conditions. Before label addition and at four successive sampling dates, the plant-soil systems were destructively harvested, separated into leaves, petioles, stems, cuttings, roots and soil and the microbial biomass was extracted from the soil. The soil CO2 efflux was sampled throughout the experiment. To model the C dynamics we used an exponential function to describe the 13C signal decline after pulse labelling. For the evaluation of the 13C distribution during the continuous labelling we suggest to use a logistic function. Pulse labelling is best suited to assess the maximum C transfer velocity from the leaves to other compartments. With continuous labelling, the mean transfer velocity through a compartment, including short-term storage pools, can be observed. The C partitioning between the plant-soil compartments was similar for both techniques, but the time of sampling had a large effect: shortly after labelling the allocation into leaves was overestimated and the soil 13CO2 efflux underestimated. The results of belowground C partitioning were consistent for the two techniques only after eight days of labelling, when the 13C import and export was at equilibrium. The C mean residence time estimated by the rate constant of the exponential and logistic function was not valid here. However, the duration of the accumulation phase (continuous labelling) could be used to estimate the C residence time. Pulse and continuous labelling techniques are both well suited to assess C cycling. With pulse labelling the dynamics of fresh assimilates can be traced, whereas the continuous labelling gives a more integrated result on C cycling, due to the homogeneous labelling of C pools and fluxes. The logistic model suggested here, has the potential to assess different parameters of C cycling independent on the sampling date and with no disputable assumptions.

An analysis of proliferative activity in innervated and denervated forelimb regenerates of the newt, Notophthalmus viridescens

Development ◽  
1987 ◽  
Vol 100 (4) ◽  
pp. 619-628 ◽  
Author(s):  
D.J. Goldhamer ◽  
R.A. Tassava
Keyword(s):  
Cell Cycle ◽  
Mitotic Index ◽  
Proliferative Activity ◽  
Thymidine Incorporation ◽  
Labelling Index ◽  
Notophthalmus Viridescens ◽  
Pulse Labelling ◽  
Adult Newt ◽  
Kinetics Of ◽  
Continuous Labelling

Pulse and continuous labelling with [3H]thymidine combined with mitotic index determinations provided data on the kinetics of cell cycling in innervated and denervated early and mid-bud forelimb blastemas of the adult newt, Notophthalmus viridescens. Most or all blastema cells cycle during regeneration and are thus part of the proliferative fraction. At any given moment, however, only 26% of the blastema cells are actively progressing through the cell cycle, with the remainder being in a state of transient quiescence (TQ). The small size of the actively cycling (AC) population may in part explain the relatively slow rate of regeneration exhibited by the adult newt. The pulse-labelling index and mitotic index of denervated blastemas paralleled control values for 48h following nerve withdrawal, but both parameters were significantly reduced by 72h. By 5 days postdenervation, cell cycle activity was essentially zero. The combined pulse and continuous labelling data suggest that nerves may be primarily involved in the entry of TQ cells into the AC population, with subsequent progression through the cell cycle being less dependent on innervation. Relative to controls, no early postdenervation increases in TCA-precipitable [3H]thymidine incorporation, pulse-labelling index or mitotic index were observed.

Contribution of the carbon sources involved in latex regeneration in rubber trees (Hevea brasiliensis): an in situ 13CO2 labelling experiment

2020 ◽  
Author(s):  
Dorine Desalme ◽  
Ornuma Duangngam ◽  
Philippe Thaler ◽  
Poonpipope Kasemsap ◽  
Jate Sathornkich ◽  
...  
Keyword(s):  
Hevea Brasiliensis ◽  
Rubber Tree ◽  
Carbon Sources ◽  
Pulse Labelling ◽  
Phloem Sap ◽  
Labelling Experiment ◽  
Latex Regeneration ◽  
Source Sink ◽  
Latex Production

&lt;p&gt;Rubber trees (&lt;em&gt;Hevea brasiliensis&lt;/em&gt;) are the main source of natural rubber, extracted from latex, which exudes from the trunk after tapping. Tapped trees require large amounts of carbon (C) to regenerate the latex after its collection. Knowing the contribution of C sources involved in latex biosynthesis will help understand how rubber trees face this additional C demand. Whole crown&lt;sup&gt; 13&lt;/sup&gt;CO&lt;sub&gt;2 &lt;/sub&gt;pulse labelling was performed on 4-year-old rubber trees in June when latex production was low and in October, when it was high. &lt;sup&gt;13&lt;/sup&gt;C contents were quantified in the foliage, phloem sap, wood and latex. In both labelling periods, &lt;sup&gt;13&lt;/sup&gt;C was recovered in latex just after labelling, indicating that part of the carbohydrates was directly allocated to latex. However, significant &lt;sup&gt;13&lt;/sup&gt;C amounts were still recovered in latex after 100 days and the peak was reached significantly later than in phloem sap, demonstrating the contribution of a reserve pool as a source of latex C. The contribution of new photosynthates to latex regeneration was faster and higher when latex metabolism was well established, in October than in June. An improved understanding of C dynamics and source-sink relationship in rubber tree is crucial to adapt tapping system practices and ensure sustainable latex production.&lt;/p&gt;

Sign in / Sign up

Export Citation Format

Share Document