Rapid changes in polyphosphoinositide metabolism associated with the response of Dunaliella salina to hypoosmotic shock
The inositol phospholipids phosphatidylinositol, phosphatidylinositol 4-phosphate (PIP), and phosphatidylinositol 4,5-bisphosphate (PIP2) comprise 14.8, 1.2, and 0.3 mol %, respectively, of Dunaliella salina phospholipids. In isolated plasma membrane fractions, PIP and PIP2 are highly concentrated, together comprising 9.5 mol % of plasmalemma phospholipids. The metabolism of these inositol phospholipids and phosphatidic acid (PA) is very rapid under normal growth conditions. Within 5 min after introduction of 32Pi into the growth medium, over 75% of lipid-bound label was found in these quantitatively minor phospholipids. Within 2 min after a sudden hypoosmotic shock, the levels of PIP2 and PIP dropped to 65 and 79%, respectively, of controls. Within the same time frame, PA rose to 141% of control values. These data suggest that a rapid breakdown of the polyphosphoinositides may mediate the profound morphological and physiological changes which allow this organism to survive drastic hypoosmotic stress. In contrast to hypoosmotic shock, hyperosmotic shock induced a rise in PIP2 levels to 131% of control values, whereas the level of PA dropped to 56% of controls after 4 min. These two different types of osmotic stress affect inositol phospholipid metabolism in a fundamentally opposite manner, with only hypoosmotic shock inducing a net decrease in polyphosphoinositides.
- Research Organization:
- Univ. of Texas, Austin (USA)
- OSTI ID:
- 6970438
- Journal Information:
- J. Biol. Chem.; (United States), Journal Name: J. Biol. Chem.; (United States) Vol. 263:12; ISSN JBCHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
ALGAE
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL STRESS
CELL CONSTITUENTS
CELL MEMBRANES
DAYS LIVING RADIOISOTOPES
DIFFUSION
ESTERS
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
LIPIDS
MEMBRANES
METABOLISM
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
OSMOSIS
OXYGEN COMPOUNDS
PHOSPHATES
PHOSPHOLIPIDS
PHOSPHORUS 32
PHOSPHORUS COMPOUNDS
PHOSPHORUS ISOTOPES
PLANTS
RADIOISOTOPES
TRACER TECHNIQUES