Influence Of Different Growth Conditions Research Articles

Influence of growth conditions on the composition of the plasma membrane from yeast and on kinetic properties of two membrane functions.

The influence of different growth conditions on the phospholipid composition and on two membrane functions, the Mg-ATPase and the purine transport system, was investigated. Addition of cholinechloride to the growth medium led to a certain rise in the amount of phosphatidylcholine, whereas supplementation with ethanolamine resulted in a considerably higher portion of phosphatidylethanolamine. When yeast cells were cultured at lower temperatures we found more short-chain fatty acids with a higher content of monounsaturated chains as compared to higher growth temperatures. Addition of paraquat, a herbicide which enhances lipid peroxidation by free radicals, reduced the amount of unsaturated fatty acids without influencing their chain length. The altered membrane composition had no influence on the basic mechanism of interaction between ATPase, MgATP, and free Mg2+ ions. However, several kinetic constants such as Km, Vmax, Ka, and especially Ki were influenced to some extent. Whereas the affinity of the purine transport system to its substrate was not significantly changed by the growth conditions, an effect on Vmax could be seen. Lower growth temperatures clearly led to higher maximal uptake velocities. The presence of paraquat during growth resulted in a considerable decrease of Vmax.

Biochemie der Leguminosen und Fouragepflanzen

IN 1938, twelve publications appeared in Russian, each containing information collected from the available literature on the biochemistry of one of the following leguminous and fodder plants : peas, beans, soya beans, dentils, clover, sweet-clover, lucerne, lupin, timothy grass, sorghum, common vetch and chick peak. The book under review, which consists mainly of tables, was compiled from the information contained in these twelve publications by the late Prof.N. N. Ivanoff of Leningrad, who unfortunately died before the printing of the book was completed. The 327 tables, with a few explanatory notes, give the chemical composition of the above-mentioned leguminous and fodder plants, each table being accompanied by the relevant reference(s). Nitrogen ('crude protein'), crude fibre, starch and/or other carbohydrates, fat and ash contents are given for all the plants mentioned, and, in addition, for most of them, figures are quoted giving the amino-acid content of the protein(s), the composition of the ash, and analytical data on the fats. Data are also included showing the influence of different growth conditions and plant varieties on the yield and chemical composition of the fodder plants. More specialized information is not contained in this book, although for clover the hydrocyanic acid, and for lupin the alkaloid content are given, and some figures are quoted for carotene and vitamin C content of peas. Biochemie der Leguminosen und Fouragepflanzen Von N. N. Iwanoff. Pp. vii+115. (Amsterdam: Dr. W. Junk, 1947.) n.p.