14 Dec

Segregation of the Pathways Leading to Cortical Reaction: DISCUSSION(4)


When Ca2+ was chelated to 150200 nM only, 14% of the eggs resumed meiosis, but half still underwent a CR. Only when the Ca2+ transient was chelated to 95 nM or lower were both aspects of activation inhibited to less than 10%. In addition, our results demonstrate that while different magnitudes of the single Ca2+ rise are important for both egg activation events, the duration of the Ca2+ rise has a minor effect. No statistical differences were found between the durations of the Ca2+ rise in the different BAPTA-AM treatments (data not shown).

Our results support previous studies demonstrating that the CR can be induced by PKC. Treating Mil eggs with different PKC activators such as TPA or OAG resulted in the CR in a concentration-dependent manner. In contrast, 4a-PDD, the biologically inactive TPA analog, did not cause the CR. Pretreatment of eggs with the PKC inhibitor, staurosporine, caused inhibition of the CR with IC50 of the 5 nM—a concentration that is accepted as specific for PKC inhibition (rat brain; rat basophilic leukemia cells ; guinea pig pancreatic acini ). Buy Asthma Inhalers Online

Assessment of the CR, as visualized by labeling of the CG exudate, revealed two patterns of labeling that were statistically different in their area fraction. Strong labeling of CG exudate represented a full CR with most CG undergoing exocytosis in each egg, while medium labeling represented eggs that underwent only a partial CR. With the various activation treatments, a concentration-dependent increase in the strong pattern of CG labeling was monitored, in correlation with increasing concentrations of TPA or Ca2+ levels.

Categories: Cortical Reaction
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