Artifactual Elevation of the Apparent Levels of Phosphatidic Acid and Phosphatidylinositol 4,5-Bisphosphate during Short-Term Labeling of Plant Tissue with Radioactive Precursor.

Some pulvini of Samanea saman Mehr. labeled with radioactive phosphate show apparent remarkable elevations of the levels of phosphatidic acid and phosphatidylinositol 4,5-bisphosphate. The elevated levels, however, appear to be illusory and to result from rapid initial incorporation of label into these phospholipids relative to others. These results demonstrate the need for caution in interpreting apparent changes in the levels of phosphatidic acid or inositol phospholipids in cultures or plants labeled with radioactive precursors.