Lemna perpusilla 6746, grown photoautotrophically at a series of sulfate concentrations ranging from 0.32 to 1,000 μM, was labeled to radioisotopic equilibrium with 35SO4
2-. Sulfur-containing ...compounds were isolated and purified from the colonies. Radioactivity in each compound was a measure of the amount of that compound present in the tissue. The following compounds were identified and quantitated: inorganic sulfate, glutathione, homocyst(e)ine, cyst(e)ine, methionine, S-methylmethionine sulfonium, S-adenosylmethionine, S-adenosylhomocysteine, cystathionine, chloroform-soluble (presumed to be sulfolipid), protein cyst(e)ine, and protein methionine. γ-Glutamylcyst(e)ine, erthro- and threo-thiothreonine, and S-methylcysteine were not detected. No volatile 35S compounds were formed during plant growth at 1,000 μM sulfate, nor were significant amounts of 35S compounds excreted into the medium. The amount of each component present in colonies grown over the 3,000-fold range of medium sulfate was relatively constant except for inorganic sulfate. This increased about 30-fold from the lowest to the highest medium sulfate concentration. The total soluble sulfur amino acids increased about 1.5- to 2-fold, due primarily to an increased amount of glutathione. Protein cyst(e)ine and protein methionine were the major organic sulfur compounds is Lemna, and the amounts of these compounds remained virtually constant despite the variation in external sulfate concentration. Procedures for the analysis of S-adenosylmethionine, S-methylmethionine sulfonium, and S-adenosylhomocysteine are presented.
An apparatus is described by means of which Lemna perpusilla 6746 was grown photoautotrophically at a series of constant concentrations of inorganic sulfate, as low as 0.26 μM. Theoretical ...considerations relevant to this system are discussed and examples of the operation of the apparatus are presented. The data obtained were used to calculate sulfate uptake by the plant colonies as a function of sulfate concentration. The apparatus should be useful for the production of relatively large quantities of Lemna, grown under highly uniform conditions, with or without limitation of one or more nutrient(s). Other small vegetatively reproducing aquatic plants could be similarly studied. Uptake studies could be carried out on a variety of plant materials.
Women in Science: The Response Benditt, John; Richmond, Geraldine; Selgrade, MaryJane K. ...
Science (American Association for the Advancement of Science),
06/1992, Letnik:
256, Številka:
5064
Journal Article
India's Struggle for Swaraj Pratt, F. G.
Journal of the Royal Institute of International Affairs,
07/1930, Letnik:
9, Številka:
4
Book Review, Journal Article
PDF
