3 Paternal Investment and lntracellular Sperm-Egg Interactions during and Following Fertilization in Drosophila

Abstract

This chapter discusses the new results and information since that time, particularly as they relate to paternal contributions, including extragenic contributions, to fertilization. This chapter describes the fundamentals of insect fertilization, fertilization and early embryonic development in the dipteran D. melanogaster, and, where appropriate, to the related insect species. Another important purpose of this chapter is to provide a forum for the speculation about the significance and purpose of the evolution of sperm gigantism in insects. In this context, four speculative models that may be relevant to this unique and intriguing biological conundrum will be presented. An even more controverial idea, that extragenic paternal investments, participate in the development of the early embryo, are discussed in the chapter. Laboratory is engaged in the biochemical and cellular analysis of some of the proteins associated with the fertilization in Drosophila. The approach has been to characterize the sperm-associated proteins identified, using monoclonal antibodies. These antibodies have identified a large family of proteins, many of which are specific to testes, related by their antibody reactivity. The evolutionary and developmental consequences of sperm structure in the egg, and the potential importance of the sperm–egg interactions during and following fertilization is discussed in the chapter. In this context, the recent advances that have led to a deeper understanding of early development, particularly the isolation of maternal-effect mutations, affecting fertilization and/or the very earliest stages immediately following fertilization are also discussed in this chapter.