Uniformly ¹⁵N‐labeled soybean seeds produced for use in human and animal nutrition studies: Description of a recirculating hydroponic growth system and whole plant nutrient and environmental requirements

Abstract

A recirculating hydroponic technique which enables the uniform "Nlabeling of soybean plants has been developed. Daily net influx of nitrate, potassium, calcium, chloride and phosphate, as well as total solution uptake, was measured for a crop of 60 plants grown in a 3 m2 area. A protocol is presented which (i) maintains adequate nutrient concentrations for the crop, (ii) adds nutrients and water as required with no exchange of solution, and (iii) minimizes the addition and use of "N. With this technique, 6.5 mol of 15N were used to generate 1 kg (DW) of soybean seeds (350 g protein kg-'; 98 atm% 15N) and 3.1 kg (DW) total biomass; recovery of nitrogen in the total biomass was 95%. "Nlabeled soy protein isolate or harvested plant parts (eg leaves or stems) can be used to investigate nutrient absorption and metabolism in human or animal studies.

Intestinal lysine metabolism is driven by the enteral availability of dietary lysine in piglets fed a bolus meal

“…We used the published ratios between aspartic acid and asparagine (41/ 59) and between glutamic acid and glutamine (44/56), determined in casein, to estimate the individual amounts of these amino acids in the meal (7). The soy protein isolate was obtained from soybeans grown hydroponically using 15 Nlabeled salts of nitrate and ammonium at the Plant Physiology Laboratory of the CNRC (14). The 15 N-labeled beans were flaked and extracted with hexane to remove oils, and the soy protein isolate was extracted, precipitated, and neutralized using standard techniques (25).…”

Stable Isotope Dilution-Based Accurate Comparative Quantification of Nitrogen-Containing Metabolites inArabidopsis thalianaT87 Cells Usingin Vivo15N-Isotope Enrichment

“…In addition, the preparation of all isotopomers corresponding to multiple target metabolites would be very laborious and time-consuming. 10,11) For our studies, we chose in vivo stable isotope metabolic labeling in cell cultures using 15 N-substituted media to overcome these drawbacks. But, so far, the method has not been used for the determination of metabolite levels in plants.…”

“…Although complete in vivo uniform labeling with 2 D, 13 C, and 15 N, or with a combination of these isotopes, is possible for E. coli, yeast, algae, and fungi, 12,13) few examples of fully stable isotope-labeled plants have been demonstrated. To date, only three examples of in vivo uniform 15 N-isotope labeling of plants have been reported, [14][15][16] and these methods require a tedious hydroponics set-up and take a long time for uniform 15 N labeling of the plant. We chose Arabidopsis suspension-cultured cells (cell line, T87) as an appropriate source to produce uniformly 15 Nlabeled metabolite material by in vivo isotope labeling methods, since fully 15 N-labeled metabolites can be…”

“…Until now, however, the role of C 1 metabolism in plant adaptation to environmental factors has been unclear. 23) We suggest that in vivo 15 N enrichment provides a useful set of Ncompounds for preliminary experiments to obtain quantitative information for physiological study rapidly. …”

Postprandial intestinal and whole body nitrogen kinetics and distribution in piglets fed a single meal

“…The meal fed to the piglets consisted of 46 ml/kg body wt of a mix of Litterlife powder and water (1:3) mixed with a trace of a uniformly and intrinsically 15 N-labeled soy protein isolate [150 mg/kg body wt, 98 atom % (AT%)]. The soy protein isolate was prepared as previously described (6,19).The total nitrogen content of the mixed meal was 46 mmol/kg body wt (SD 1) (3.1 AT%). The liquid meal was fed orally and ingested quickly, within 45 min.…”