Echindoderm gametes make PAF; Artificial activation by external PAF bipasses calcium channels regulated by 2APB unlike jelly activation of sperm

摘要

The search for lipid changes at fertilization shows production of PAF, a phospholipid known as Platelet Activating Factor. Effects on gametes by externally applied PAF suggest it may be involved in several less understood calcium dependent events of fertilization. PAF artificially activates both echinoderm eggs and Sperm. Calcium channel drugs 2APB, ruthenium red, nitrendipine and nifedipine and pH 5 SW do not prevent it, but external calcium must be present. 2APB does prevent normal jelly activation of sperm. Egg PAF activation includes cortical reaction or cell shape change. Sperm PAF activation increases adhesivity, the sperm winds up on itself, or dissociates the acrosome, nucleus and mitochondria. Natural PAF produced could alter cell activation, adhesion, fusion, fertilization cone and sperm nuclear changes after entry into egg. Positive effects of PAF and its receptor on capacitation, activation of sperm and embryo viability have been known from in vitro fertilization studies, but mechanisms remain mysterious.