RESUMO
In Chlamydomonas eugametos gametes, phosphatidylinositol 4-phosphate (PtdInsP) and phosphatidylinositol 4,5-bisphosphate (PtdInsP2) comprised 0.4 and 0.3% of the whole-cell phospholipids. They were concentrated in the plasma membrane around the cell body and were present in low concentrations in the flagellar membrane. When gametes were fed (32)PO 4 (-) , the label was rapidly incorporated into PtdInsP and PtdInsP2 and only slowly incorporated into structural lipids such as phosphatidylethanolamine and phosphatidylglycerol. Similarly, when a pulse of (32)PO 4 (-) was chased with PO 4 (-) , the label was rapidly lost from the polyphosphoinositol lipids but not from the structural lipids. The major fatty acids in the polyphosphoinositides were C-22 carbon polyenoic acids (70%). The significance of these results in relationship to intracellular signalling via inositol phosphates and Ca(2+) is discussed.
RESUMO
For mating Chlamydomonas eugametos gametes to fuse with their partners, they must first lyse part of the anterior cell wall and protrude their mating structures. These responses can be artificially induced by compounds that raise the Cai level, viz. InsP3, A23187, TFP and ethanol. We conclude that calcium should be considered with cAMP to be involved in signal transduction during C. eugametos mating.
