Uniformly 14C-labelled plant cell walls: production, analysis and behaviour in rat gastrointestinal tract.
Uniformly 14C-labelled primary cell walls (14C-PCW) were purified from suspension-cultured cells of spinach (Spinacia oleracea L.) grown in a medium containing D-[U-14C]glucose. The approximate polymer composition of the 14C-PCW preparation (% total 14C) was homogalacturonan 30, rhamnogalacturonan 23, xyloglucan 10, other hemicelluloses 3, cellulose 21, lignin 0, 14C-labelled protein < 3 and [14C]starch < 2. The degree of methyl esterification of the pectic polysaccharides was about 25%. The 14C-PCW contained about 4% O-acetyl and 3% non-volatile ester-linked residues. When tracer levels of these 14C-PCW were fed to rats, only about 18% of the 14C appeared in the faeces; negligible levels of 14C (0.07%) remained in the gut contents 4 d after feeding. Some 14C was present in the carcass. The results show that U-14C-labelled primary cell walls can be purified and radiochemically analysed by the methods developed here, and that primary cell walls are extensively fermented by the gut microflora of the rat.
Centre for Plant Science, University of Edinburgh.
D F
DF
Gray
S C
SC
Fry
M A
MA
Eastwood
D000818:Animals; D002250:Carbon Radioisotopes / Q000378:metabolism; D002473:Cell Wall / Q000737:chemistry / Q000378:metabolism*; D004043:Dietary Fiber / Q000378:metabolism; D004064:Digestive System / Q000378:metabolism*; D005285:Fermentation; D008297:Male; D010945:Plants, Edible / Q000737:chemistry / Q000378:metabolism*; D011134:Polysaccharides / Q000032:analysis / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
D002250:Carbon Radioisotopes; D004043:Dietary Fiber; D011134:Polysaccharides