Modification of the intracellular signaling machinery leading to the acquisition of sperm fertilizing ability

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The major objective of my research program is to better understand the mechanisms by which sperm acquire the ability to interact with and fertilize the egg.  Sperm intracellular biochemical machinery is modified during this process.  There are several signalling cascade that are triggered either by poorly defined factors from the female reproductive tract, by the egg itself, or by follicular products that are released with the egg during the ovulation process.  We identified sperm intracellular proteins that are suspected to be part of a signalling pathway activated as sperm become fertilization competent.  However, the partners of these enzymes have not been identified.  One of our goals is therefore to identify the factors upstream and downstream of our proteins in order to have a better idea of what is happening to sperm to make them competent at fertilizing.  Furthermore, sperm/egg interactions are highly specific phenomena.  With only rare exceptions, sperm from one animal specie can only fertilize an egg from the same specie.  Proteins from both gametes are involved in this recognition process.  We identified and partly purified one of the sperm proteins putatively responsible for the sperm binding to the egg.  As this protein is modified when sperm undergo epididymal maturation, we are greatly interested to identify the nature of these modifications.  In addition, we suspect that this protein is also affected as sperm acquires its fertilizing competence.  It is, therefore, important to determine the nature of these modifications and to understand how they affect the ability of this protein to mediate the interactions between sperm and egg.  Under natural conditions, fertilization occurs within the female genital tract, in the oviduct.  Therefore, sperm acquire its ability to interact with and fertilize the egg during its internal transit toward the egg.  A part of my research program is to determine how the uterus or oviducts render sperm fertilization competent.  Is it through direct cellular interactions between sperm and epithelial cells or through secretions from the female reproductive tract?