EXTRACTIONS REVEAL SPECIFIC ARGENTOPHILIC PROTEINS IN RAT AND BULL SPERM HEADS

Background: Silver-stainability (argentophilia) of cytoplasmic structu res occurring in spermatids have been localized into the organizing pe rinuclear theca, but the biochemical nature and structural association s of these proteins with the cytoskeletal and membranous elements are unresolved and, therefore, were the aim of the present study. Methods: Light and electron microscopic analysis of the silver-stainability in the rat spermatids and spermatozoa was carried out in the intact test is tissue and epididymal spermatozoa and after their chemical and mech anical extraction. Correlation of argentophilia with specific proteins of rat and bovine spermatids and spermatozoa was investigated using a recently developed technique for silver nitrate staining of proteins on nitrocellulose. Results: Sequential formation of the silver-stainab le domains seemed to proceed from the argentophilic acrosomal ring. Va rious extractions indicated that argentophilia in the spermatids and s permatozoa was mainly associated with the perinuclear theca and to som e extent to the plasma membrane. Hyamine-soluble extract from spermato zoa of rat and bull revealed only a single argentophilic protein of 13 0 kDa. Hyamine and SDS-soluble extracts of rat testis tissue contained an additional group of argentophilic polypeptides of lower molecular weight (115, 94, 36, 23, and 21 kDa). Conclusions: Reduction in the nu mber of argentophilic proteins appears to be involved in a series of c hanges in the cyto-architecture of developing spermatids. Tentative cy toskeletal nature of argentophilic proteins remains to be identified. Nevertheless, they may have important physical relations with the high er-order organization of the sperm head cytoskeleton and overlying mem branes. (C) 1994 Wiley-Liss, Inc.