No abstract

No abstract

No abstract

Glucose-6-phosphate dehydrogenase (G6PD) is present in different mixtures of interchangeable states of aggregation in each of the supernatant and pellet fractions of unfertilized and fertilized sea urchin eggs. These states are each altered differently by redox agents, as shown by changed electrophoretic isozyme patterns and altered filtration retention following treatment by diamide, oxidized glutathione, reduced glutathione, ascorbate, or dithiothreitol. Activity levels of G6PD are altered by redox agents, probably as a result of change in aggregation state or change in association with inhibitory associated molecules. This suggests that there are control mechanisms for G6PD that are in different conditions in unfertilized vs. fertilized stages and supernatant vs. pellet compartments, resulting in different states of G6PD in the isolates.

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.