Detection and Measurement of Membrane-Bound Protein Tyrosine Kinases in the Zebrafish Egg

The study of the biochemical events involved in fertilization and egg activation has historically been directed toward marine invertebrate and amphibian eggs (1 ), although recent progress has been made in the analysis of a few enzymes that are abundant in mammalian eggs (2 ,3 ). The zebrafish system is also a promising model that shares several advantages with marine invertebrate eggs, yet has the advantage of being a vertebrate. For example, the zebrafish eggs are reasonably clear optically and can be obtained in quantities suitable for biochemical analysis. They can be fertilized synchronously and will develop rapidly (4 ). The zebrafish system also benefits from the fact that the DNA sequence homology with mammals is very high, so that tools developed in mammalian systems can be applied to zebrafish eggs with a reasonable expectation of success. Finally, the potential for genetic analysis of the fertilization process could ultimately provide novel insights into the signaling mechanisms used at fertilization.