Quin2-induced metaphase arrest in stamen hair cells can be reversed by 1,2-dioctanoylglycerol but not by 1,3-dioctanoylglycerol.

Elicitor molecules of the polyphosphoinositide cycle, inositol 1,4,5-trisphosphate (InsP3) and 1,2-diacylglycerol (1,2-DAG) play roles in the entry of calcium into the cytosol and in the elevation of protein kinase C activity, respectively. We have treated stamen hair cells of the spiderwort plant, Tradescantia virginiana, with a solution of quin2 (50 microM) or its acetoxymethyl ester, quin2-AM (50 microM) and have retarded the normally predictable rate of progression through metaphase. Metaphase arrest persists for longer than 80 min after treatment with this Ca2+-chelator, and, shortly thereafter, the cells revert to interphase without dividing. Reversal of metaphase arrest results from treatments with calcium chloride (100 microM) after 5 to 8 min or with 1,2-DAG (i.e., 60 micrograms/ml 1,2-dioctanoylglycerol) after 7 to 11 min. In control experiments, metaphase arrest could not be reversed by treatment with either magnesium sulfate or 1,3-dioctanoylglycerol. Anaphase onset was observed in these control cells after post-treatment with calcium chloride (after 4-9 min) or with 1,2-dioctanoylglycerol (after 7-13 min). The treatment of stamen hair cells in very early prophase with H-7, (i.e., 1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride), a potent protein kinase C inhibitor, extends the duration of metaphase significantly. Neither H-8 nor HA-1004, less active protein kinase C inhibitors in this class of molecules, alter the duration of metaphase to a significant extent. These results suggest that in cells arrested in metaphyase by quin2, calcium translocation plays a role in the sequence of events which culminate in anaphase.(ABSTRACT TRUNCATED AT 250 WORDS)