Immunodissection of sperm surface modifications during epididymal maturation

Abstract

Mammalian spermatozoa undergo changes in morphology, composition, and function during transit through the epididymis. These changes correlate with acquisition by sperm of the ability to fertilize ova. It has been found that sperm from the cauda epididymidis, but not those from the caput epididymidis, are able to bind to the zona pellucida. This would imply a modification in sperm surface characteristics. Biochemical and immunological studies have demonstrated changes in sperm surface composition during epididymal maturation. These changes involve addition of epididymal secretory products to the sperm surface, loss or alteration of existing sperm surface molecules, and possibly the unmasking of preexisting molecules or epitopes. Several laboratories have studied the epididymal secretory proteins in the rat, but a consensus has not been reached on the identification, characterization, source, and sperm surface association of these proteins. Monoclonal antibodies are beginning to be used to characterize sperm surface components and sperm maturation antigens. They are proving to be valuable tools for the dissection of epididymal maturation when used in conjunction with biochemical and physiological approaches.

Predicted seminal astacin-like protease is required for processing of reproductive proteins in Drosophila melanogaster

“…In mammals, passage through the male reproductive tract results in modifications to proteins on the sperm surface (32,33). To determine whether Drosophila seminal proteins are processed during passage through the male reproductive tract, we interrupted matings at 8 and 10 min after the start of mating (ASM) [mating between wild type (Canton-S) flies typically lasts for 20 min] and analyzed proteins from the seminal fluid mixture in the mating male's ejaculatory duct/bulb.…”

Endoproteolytic cleavage in the extracellular domain of the integral plasma membrane protein CE9 precedes its redistribution from the posterior to the anterior tail of the rat spermatozoon during epididymal maturation [published erratum appears in J Cell Biol 1991 Nov;115(3):following 880]

“…As a consequence, it would be logical to assume that these domains were formed as the spermatidsunderwent morphological polarization during the process ofspermiogenesis (Fawcett et al ., 1971;Clermont, 1972;Hamilton, 1989) . However, there is now mounting experimental evidence to support the notion that the plasma membrane domains of the mature spermatozoon are not constructed solely during spermiogenesis, but that they are also the result ofextensive remodelingboth during transit through the epididymis (Olson and Hamilton, 1978 ;Jones et al ., 1983 ;Eddy et al, 1985 ;Holt, 1984;Jones, 1989;Phelps et al, 1990) and probably also during the processes of capacitation and the acrosome reaction (Friend et al ., 1977;O'Rand, 1979; .…”

Mannose-6-Phosphate Receptors as a Molecular Indicator of Maturation of Epididymal Sperm

“…Some authors have ascribed a role for these enzymes in sperm maturation , related to the changes that the gametes undergo during epididyma l transit [26]. However, there is no clear evidence supportin g this, since the epididyma l milieu does not provide the optimal pH for their enzymatic activity.…”