Phospholipid signaling during stramenopile development.

Development of sessile organisms requires adaptation to an ever-changing environment. In order to respond quickly to these challenges, complex signaling mechanisms have evolved to facilitate cellular modifications. The importance of phospholipid-based signaling pathways in plants, as well as animals, has recently been gaining attention. Both the PLD and PLC pathways produce the signaling molecule PA, which modulates MTs, F-actin and endomembrane trafficking. We have examined the roles of the PLD signaling pathway during development of the marine brown alga Silvetia compressa. Zygotes were treated with 1- and 2-butanol, both of which activate the PLD enzyme. However, only 1-butanol competes with water as a transphosphatidylation substrate, at the expense of PA production. Interestingly, we found that 1- and 2-butanol both disrupted MT organization and thereby cell division, with 1-butanol being more potent. These findings question whether the effects of butyl alcohol treatment are due to lowered PA levels or activation of the PLD enzyme. Additionally, preliminary results show that inhibition of DAGK results in loss of centrosomal MTs and formation of cortical MT cages that are strikingly similar to those formed following 1-butanol treatment. These data suggest that perturbation of the PLD or PLC pathway leads to cortical stabilization and/or nucleation of MT arrays.