Abstract
Interactions between the spermatozoa and egg during fertilization include the acrosome reaction, sperm-egg binding and fusing, egg activation, and interactions between gametic nuclear material. Fertilization maybe blocked at any point during these interactions, resulting in gametic incompatibility. From an ecological perspective, gametic incompatibility maintains the genetic structure of existing species. Previous studies have demonstrated that closely related individuals of the Eastern oyster, Crassostrea virginica (Gmelin), have a lower fertilization success and zygote survival than do those individuals that are genetically divergent. Pair crosses between individual oysters from Galveston Bay, Texas were performed in this study to determine if gametic interactions varied between crosses. Data analysis revealed variation between crosses in the rate of sperm-egg binding, sperm-egg fusion, and egg activation. In the four half-sibling families analyzed, the families resulting from one sire required an average of 14 minutes to progress through the acrosome reaction, sperm-n-egg binding, and fusing; subsequent progression through egg activation took an additional 36 minutes. Fertilization in families sired by a different male progressed at a more rapid rate (2.5 minutes for the acrosome reaction, binding, and fusing and 4 minutes for egg activation). No variation in process rates between families was exhibited during the meiotic and mitotic interactions of fertilization. Mortality between families varied extensively. Variation in rates between families during the early phases of fertilization, in combination with the variation in overall mortality, suggested that molecular interactions involved with binding, fusing, and egg variation in paired crosses. The results are consistent with the hypothesis that polymorphisms in the physical properties of C virginica gametes exist, therefore some paired crosses are, gametically, less compatible than others.
Armstrong, Stephanie Celeste (1997). Fertilization success and zygote survival in the Galveston Bay population of Crassostrea virginica (Gmelin), the eastern oyster. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1997 -THESIS -A76.