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Abstract

G dynamics as a marker for membrane changes associated with the process of capacitation in murine and bovine spermatozoa 
Selvaraj,Vimal; Buttke,Danielle E.; Asano,Atsushi; McElwee,John L.; Wolff,Collin A.; Nelson,Jacquelyn L.; Klaus,Angela V.; Hunnicutt,Gary R.; Travis,Alexander J.
Journal of Andrology 28(4): 588-599
Publication date: 2007


We previously showed that in live murine and bovine sperm heads,the ganglioside G localizes to the sterol-rich plasma membraneoverlying the acrosome (APM). Labeling G using the pentamericcholera toxin subunit B (CTB) induced a dramatic redistributionof signal from the APM to the sterol-poor postacrosomal plasmamembrane (PAPM) upon sperm death. We now show a similar phenomenonin the flagellum where CTB induces G redistribution to sterol-poormembrane subdomains of the annulus and flagellar zipper. Becausesterol efflux from the plasma membrane is required for capacitation,we examined whether G localization might be useful to detectmembrane changes associated with capacitation and/or acrosomalexocytosis. First, incubation of murine and bovine sperm withtheir respective stimuli for capacitation did not change Gdistribution in live cells. However, incubation of sperm ofboth species with specific stimuli for capacitation, followedby the use of specific fixation conditions, induced reproducible,stimulus-specific patterns of G distribution. By assessingchanges in G distribution in response to progesterone-inducedAE, we show that these patterns reflect the response of murinesperm populations to capacitating stimuli. These data suggestthat G localization can be used as a diagnostic tool forevaluating sperm response to stimuli for capacitation and/orAE. Such information could be useful when deciding betweentechnologies of assisted reproduction or when screening formale fertility. Furthermore, stimulus-specific changes in Gdistribution showed that sperm could respond to NaHCO or mediatorsof sterol efflux independently, thereby refining existing modelsof capacitation.