This research will apply new technological advances to the study of an outstanding biological question - how do sperm-egg interactions during and following fertilization affect reproductive success? The primary role of sperm has traditionally been viewed as a delivery vehicle for the "DNA cargo." However, recent evidence indicates that sperm may play a more fundamental role in fertilization and early development. For example, in almost all cases examined, including humans and other mammals, the entire sperm cell enters the egg at fertilization. Sperm structure within the egg may therefore be an essential element of fertilization, as supported by the existence of Drosophila mutants defective in both sperm structure within the egg and subsequent embryonic development. This incompatibility between sperm inside the egg may represent an unrecognized mechanism of sterility between individuals.
Sperm-egg incompatibility will be studied in three steps using Drosophila: (1) the 3D structure of sperm inside eggs from matings of the same species will be determined and compared with, (2) the 3D sperm structures inside eggs from matings between different species. Information gathered in (1) and (2) will be used for a detailed analysis of the fitness consequences of altered sperm-egg interactions. (3) 3D sperm structure will be determined using the CAVE, a virtual reality environment, in which 3D projections of sperm inside eggs will be traced and compared. The use of the CAVE represents a novel application of super computing technology to complex biological processes. The ubiquitous nature of sperm-egg interactions during and following fertilization suggest that these findings will have relevance to the reproductive biology to a wide range of animals, including endangered species and humans.
