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Accueil du site → Master → Etats Unis → 1972 → The effect of high temperature on the lipid composition and chloroplast ultrastructure of creosotebush (Larrea divaricata Cav.)

University of Arizona (1972)

The effect of high temperature on the lipid composition and chloroplast ultrastructure of creosotebush (Larrea divaricata Cav.)

Sprenger, Paulette Jean

Titre : The effect of high temperature on the lipid composition and chloroplast ultrastructure of creosotebush (Larrea divaricata Cav.)

Auteur : Sprenger, Paulette Jean,

Université de soutenance : University of Arizona

Grade : Master of Science (MS) 1972

Résumé
The purpose of this thesis was to investigate the effect of high temperatures (45 C) on the lipid composition and ultrastructure of creosotebush leaves (Larrea divaricata Cav,), Lipid analyses of field grown plants showed that heat caused no significant qualitative or quantitative changes in the phospholipids and monogalactosyl diglycerides , but heat increased the quantity of the digalactosyl diglycerides significantly when Compared to plants grown at 25 C. The specific activity of the galactolipids averaged 1,5 cpm/gram dry weight. Lipid analysis of the six month old seedlings showed that heat caused no qualitative change in the phospholipids or galactolipids of the 45 C grown plants, however, heat did reduce the incorporation of sodium acetate- into phospholipids by 75% while it increased the incorporation into galactolipids by 138%, The heat treated seedlings and field plants had large lipid globules in the chloroplast while 25 C grown plants had fewer globules. These globules varied from 0.3 to 0,8 microns in diameter y and were stained darkly in the presence of OsO^. The labeling experiments with seedlings indicated that heat induced a reduction of phospholipid synthesis a,nd stimulated, galactolipid synthesis, The increased galactolipid synthesis and .quanity may correlate with increased numbers of chloroplast lipid globules.

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