The long range goal of these studies is to understand how the organization and physical properties of the mammalian sperm plasma membrane change with maturation in the epididymis and capacitation in the female tract, and how these modifications are related to important physiological alterations which occur in the male and female tracts, specifically the development of sperm motility, the acrosome reaction, and the potential to fertilize ova. Work from a number of laboratories on sperm from various mammalian species has shown that the sperm plasma membrane is highly organized, that different membrane components are localized in different regions of the membrane, and that this organization and localization changes with sperm maturation and capacitation (1-8). To effect this regionalization, the sperm must restrict or overcome the free random diffusion of their membrane components. In order to determine the nature of these restrictions to free diffusion and to understand how these restrictions change with maturation and capacitation, we propose to use fluorescence recovery after photobleaching, intensified video fluorescence microscopy, and rapid freeze deep etch electron microscopy to study changes in the ram sperm plasma membrane upon maturation and capacitation. Specifically we will address the following questions: 1. What are the restrictions to lipid and protein diffusion which lead to the localized distributions of these membrane components on mammalian spermatozoa 2. How do the diffusibility of sperm membrane lipids and protein change during maturation and capacitation 3. What is the nature of the processes which result in the redistribution of membrane components during maturation and capacitation 4. To what extent does motility and hyperactivated motility control the distribution and redistribution of membrane components

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Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
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Reproductive Biology Study Section (REB)
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Worcester Foundation for Biomedical Research
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Smith, T T; McKinnon-Thompson, C A; Wolf, D E (1998) Changes in lipid diffusibility in the hamster sperm head plasma membrane during capacitation in vivo and in vitro. Mol Reprod Dev 50:86-92
Cardullo, R A; Wolf, D E (1995) Distribution and dynamics of mouse sperm surface galactosyltransferase: implications for mammalian fertilization. Biochemistry 34:10027-35
Wolf, D E (1995) Lipid domains in sperm plasma membranes. Mol Membr Biol 12:101-4
Wolf, D E (1992) Theory of fluorescence recovery after photobleaching measurements on cylindrical surfaces. Biophys J 61:487-93
Wolf, D E; McKinnon, C A; Leyton, L et al. (1992) Protein dynamics in sperm membranes: implications for sperm function during gamete interaction. Mol Reprod Dev 33:228-34
McKinnon, C A; Weaver, F E; Yoder, J A et al. (1991) Cross-linking a maturation-dependent ram sperm plasma membrane antigen induces the acrosome reaction. Mol Reprod Dev 29:200-7
Venkatakrishnan, G; McKinnon, C A; Pilapil, C G et al. (1991) Nerve growth factor receptors are preaggregated and immobile on responsive cells. Biochemistry 30:2748-53
Wolf, D E; Maynard, V M; McKinnon, C A et al. (1990) Lipid domains in the ram sperm plasma membrane demonstrated by differential scanning calorimetry. Proc Natl Acad Sci U S A 87:6893-6
Wolf, D E (1989) Designing, building, and using a fluorescence recovery after photobleaching instrument. Methods Cell Biol 30:271-306
Wolf, D E; Lipscomb, A C; Maynard, V M (1988) Causes of nondiffusing lipid in the plasma membrane of mammalian spermatozoa. Biochemistry 27:860-5

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