Metabolism of [1-14C]glyoxylate, [1-14C]-glycollate, [1-14C]glycine and [2-14C]-glycine by homogenates of kidney and liver tissue from hyperoxaluric and control subjects

1. The metabolism of [1-(14)C]glyoxylate to carbon dioxide, glycine, oxalate, serine, formate and glycollate was investigated in hyperoxaluric and control subjects' kidney and liver tissue in vitro. 2. Only glycine and carbon dioxide became significantly labelled with (14)C, and this was less in the hyperoxaluric patients' kidney tissue than in the control tissue. 3. Liver did not show this difference. 4. The metabolism of [1-(14)C]glycollate was also studied in the liver tissue; glyoxylate formation was demonstrated and the formation of (14)CO(2) from this substrate was likewise unimpaired in the hyperoxaluric patients' liver tissue in these experiments. 5. Glycine was not metabolized by human kidney, liver or blood cells under the conditions used. 6. These observations show that glyoxylate metabolism by the kidney is impaired in primary hyperoxaluria.     

Biosynthesis of [14C]zearalenone from [1-14C]acetate by Fusarium roseum 'Gibbosum'.

Addition of [1-14C]acetate or [1,2-14C]acetate to actively growing cultures of Fusarium roseum 'Gibbosum' on rice yielded zearalenone with a specific activity ranging between 1.63 and 46.5 microCi/mmol.     

Quantitative measurement of the L-type pentose phosphate cycle with [2-14C]glucose and [5-14C]glucose in isolated hepatocytes.

1. Investigations of the mechanism of the non-oxidative segment of the pentose phosphate cycle in isolatd hepatocytes by prediction-labelling studies following the metabolism of [2-14C]-, [5-14C]- and [4,5,6-14C]glucose are reported. The 14C distribution patterns in glucose 6-phosphate show that the reactions of the L-type pentose pathway in hepatocytes. 2. Estimates of the quantitative contribution of the L-type pentose cycle are the exclusive form of the pentose cycle to glucose metabolism have been made. The contribution of the L-type pentose cycle to the metabolism of glucose lies between 22 and 30% in isolated hepatocytes. 3. The distribution of 14C in the carbon atoms of glucose 6-phosphate following the metabolism of [4,5,6-14C]- and [2-14C]glucose indicate that gluconeogenesis from triose phosphate and non-oxidative formation of pentose 5-phosphate do not contribute significantly to randomization of 14C in isolated hepatocytes. The transaldolase exchange reaction between fructose 6-phosphate and glyceraldehyde 3-phosphate is very active in these cells.     

Isoprenoid biosynthesis in a marine sponge of the Amphimedon genus: incorporation studies with [1-14C] acetate, [4-14C] cholesterol and [2-14C] mevalonate

1. We present quantitative evidence from incorporation of [1-14C] acetate that the enzymes to synthesise isoprenoids are present in the marine sponge Amphimedon sp. and that efficient carotenoid synthesis takes place. 2. The de novo synthesis of b,b-carotene and (3R,3'R)-zeaxanthin may occur in a chlorophyll a-producing microalgal symbiont with subsequent aromatisation to (3R)-isoagelaxanthin by the sponge itself. 3. Amphimedon sp. contains nuclear-modified sterols derived by modification of conventional dietary sterols.     

Metabolism of ent-kaurenol-[17-14C], ent-kaurenal-[17-14C] and ent-kaurenoic acid-[17-14C] by germinating Hordeum distichon grains

Subcellular fractions from germinated barley embryos, chloroplast preparations and whole germinating barley grains are able to carry out the conversions ent-kaurenol → ent-kaurenal → ent-kaurenoic acid → ent-hydroxykaurenoic acid, the initial steps of the biosynthetic pathway to gibberellins. Whole grains, and chloroplasts to a slight extent, incorporate radioactivity from ent-kaurenol-[17-¹⁴C] and ent-kaurenoic acid-[17-¹⁴C] into materials with similar but distinct properties from the gibberellins GA₁, GA₃, GA₄ and GA₇.