Excellence in Research: The Role of Bovine Sperm Acrosome in Fertilization

This project will elucidate the role of certain proteins in the activation of the acrosome in cows. The acrosome is a small compartment in sperm cells that releases enzymes to allow the sperm to penetrate the protective layer surrounding the egg. The PI has characterized two novel proteins in the acrosome, and will characterize the function and ability of these proteins to bind to calcium and to bind to other acrosomal proteins to form a complex that activate the acrosome just prior to fertilization.

This project will provide increased understanding of fundamental aspects of mammalian fertilization, as well as contributing to improved strategies for maintaining and activating stored spermatozoa and improving fertilizing capacity of stored sperm for needs of agriculture, zoological preservation, and reproductive health. The projects will also increase opportunities for undergraduates and high school students at this HBCU to learn the ethics of science and receive hands-on experience/skills with modern biochemical and cell biological techniques.

Most of the PI's previous lab students have since matriculated into various graduate and professional programs. The results of this project will thereby increase the pool of future Ph.D. scientists from underrepresented groups, as well as facilitate high school students' admission into research-intensive schools for baccalaureate programs.

The calcium-dependent acrosome reaction is a key control point in mammalian fertilization, but numerous unresolved signaling events and biochemical mechanisms that promote membrane fusion of the acrosome to the sperm plasma membrane remain poorly understand. The goal of this project is to identify the biochemical mechanisms that regulate the role of acrosomal proteins in membrane fusion and the release of hydrolases during the acrosome reaction of bovine sperm.

The PI’s work has characterized a 32kDa acrosomal polypeptide (OMC32) essential for membrane fusion that is present in the bovine sperm acrosome. The project here will examine the hypothesis that OMC32 interacts with other acrosomal proteins to regulate release of hydrolases and other acrosomal proteins essential to completing the acrosome regulation, and whether OMC32 is an essential target of signal transduction elements and regulatory proteins that mediate the acrosome reaction.

In a second aim, the PI and students will examine a novel 64kDa calcium-binding protein in the outer acrosomal membrane. Here, the project will test the hypothesis that this calcium-binding protein regulates fusion between the acrosomal membrane and the sperm plasma membrane. Besides extensive training of high school and undergraduate students in research as a career, this project will contribute to greater understanding of sperm membrane fusion, acrosome integrity and function, and mammalian fertilization.

The results may also contribute to improved strategies for maintaining acrosomal integrity in stored spermatozoa, and improving the fertilizing capacity of mammalian spermatozoa, with potential benefits of maintaining stock for the cattle industry, for endangered mammal species, as well as for human reproductive health.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.