Localization of actin, α‐actinin, and tropomyosin in bovine spermatozoa and epididymal epithelium

Abstract

Actin, alpha-actinin, and tropomyosin were localized in the testicular, epididymal, and ejaculated spermatozoa and in the epithelium of the bovine epididymis by means of specific antibodies using an indirect immunofluorescence technique. Immunocytochemical results were confirmed by the western blot analysis. Independent of the method of fixation, washing, or sonication, actin, alpha-actinin, and tropomyosin were all consistently localized in the neck of the spermatozoa. Actin and tropomyosin present in the postacrosomal area could be removed by sonication, whereas alpha-actinin in the basal plate appeared to be resistant to the treatment. In the unwashed spermatozoa alpha-actinin-specific immunofluorescence was seen over the acrosomal area, whereas in the washed sperm it appeared as a narrow cap at the margin of the head. In the latter location, its distribution was similar to that of tropomyosin. In the majority of preparations, tropomyosin could be localized in the principal piece of the tail. Even though some actin-specific immunofluorescence could be identified in the principal piece of the tail of the testicular and epididymal spermatozoa, a strong immunoreaction appeared only in the ejaculated spermatozoa. In the principal cells of the epididymal epithelium, specific fluorescence for actin, alpha-actinin, and tropomyosin occurred in the apical junctional complex. Basal bodies of the solitary cilia of the epididymal epithelium were labelled with antitropomyosin and anti-alpha-actinin antibodies. Besides offering new information about the cytoskeletal composition of the mammalian sperm, the present results support the hypothesized homology between the connecting piece of the sperm neck and the basal body of the cilia.

Actin, α‐actinin, and spectrin with specific associations with the postacrosomal and acrosomal domains of bovine spermatozoa

“…In the bovine spermatozoa, only a-actinin and tropomyosin have been localized in the acrosomal area neck is still to be identified. The same consensus holds for actin (Virtanen et al, 1984;Flaherty et al, 1986Flaherty et al, , 1988Holt and North, 1991;Yagi and Paranko, 1992) and actin-associated proteins (Virtanen et. al., 1984;Yagi and Paranko, 1992) described in the tail of the mammalian sperm.…”

“…Indicated are plasma membrane (PM), outer acrosomal membrane (OAM), inner acrosomal membrane (IAM), acrosomal lamina (L), acrosomal crescent (C), nuclear envelope (E), lateral prongs (LP), postacrosomal sheath (PAS), perinuclear patches (PN), posterior ring (R), posterior ring structure (PR), capitulum (CA), segmented columns (SC), outer dense fibers (OF), and axoneme (AX). (Yagi and Paranko, 1992). In the equatorial segment, actin has so far been described only in boar spermatozoa (Camatini et al, 1986).…”

“…The biological role of nonfilamentous actin (Virtanen et al, 1984;Flaherty et al, 1988;Yagi and Paranko, 1992), tropomyosin, a-actinin (Yagi and Paranko, 19921, myosin (Virtanen et al, 1984), and ankyrin (Kann et al, 1993) in the sperm Reduced labeling is seen in principal piece (P) of the MgC1,-extracted spermatozoa. f,f': Sonicated spermatozoa show staining in the neck (N) and in the fragments of the principal piece (P).…”

“…A rigid postacrosomal sheath is a putative site for actin in a number of mammalian spermatozoa (Clarke and Yanagimachi, 1978;Tamblyn, 1980;Clarke et al, 1982;Flaherty et al, 1986Flaherty et al, , 1988Yagi and Paranko, 1992), where it may interact with actin-binding proteins such as spectrin (Kann et al, 1993) and a group of basic proteins including calicin and multiple band proteins (Longo et al, 1987;Paranko et al, 19881, and with less well identified silver binding proteins (Yagi and Paranko, 1994).…”

Functional identity of the Gamma Tropomyosin gene

“…Tm gene products have been detected in a previous study in bovine spermatozoa. 36 However the expression profile of individual Tm gene products in mouse sperm has not been studied so far. Our data demonstrates that Tm products from all Tm genes are expressed in mouse sperm and that there appears to be no differences in the expression of the products between 129/SvJ and C57BL/6 mouse lines.…”