Structure, cytoskeleton, and development of the acrosome of Platycleis albopunctata (Orthoptera: Tettigoniidae)

Abstract

The acrosome of Platycleis albopunctata (Orthoptera: Tettigoniidae) is relatively large and complex, consisting of an apical vesicle and two large wing-like extensions that give the spermatozoon the shape of an arrow. The wings have actin microfilaments and microtubules and are covered with a noticeable extracellular material. Actin filaments are present in the acrosome when it first appears in spermatid stages. The acrosome and the acrosomal attachment to the nucleus are more resistant than other structures to the reducing agents DTT and SDS. At the end of spermiogenesis, groups of spermatozoa juxtapose their sperm heads and become joined to form a spermatodesm encircled by an amorphous material. Treatment with the ionophore A23187 rapidly disrupted acrosomes of the free gametes, but acrosomes from spermatozoa contained in the spermatodesm were not disassembled. Packaging of sperm in a spermatodesm appears to protect the acrosome.

Fluorescence microscopy study on the cytoskeletal displacements during sperm differentiation in the bush‐cricket Tylopsis liliifolia (Fabricius) (Orthoptera: Tettigoniidae)

“…The latter finding, however, in disagreement with what shown in the bush‐cricket Platycleis albopunctata (Guerra and Esponda, ), reinforces the hypothesis that microtubules could be involved only in the twisting of the acrosomal wings around the anterior region of the gamete. Furthermore, the presence of α‐tubulin only in the anterior tract of the acrosomal region could be related to a probable involvement of this molecule in the interaction with the female gamete, similar to what suggested for mammals (Dvořáková et al, ).…”

“…Although the presence of microtubules in this region of the male gamete has been so far reported in species of several orders of insects (Baccetti and Afzelius, 1976;Guerra and Esponda, 1999;Jamieson, 1987;Phillips, 1970), it should be noted that also previous ultrastructural investigations on the genesis of the spermastodesms of T. liliifolia have shown a sheath of microtubules around the nucleus of the maturating spermatids (Viscuso et al, 2012), easily corresponding to the microtubular manchette of the grasshoppers Acrididae (Rattner and Brinkley, 1972;Sz€ oll€ osi, 1975).…”

“…The latter, in fact, is a highly organized dynamic structure, generally allowing the eukaryotic cells to perform regulated and specialized activities in response to various stimuli, whether from the intracellular microenvironment or from the external one (Alberts et al, 1994;Cappuccinelli, 1987;Carraway and Carraway, 2000). Moreover, it is known for a long time now that microfilaments and microtubules play a major role, among the cytoskeletal components, in the organization and motility of the male gamete and its interaction with the female gamete (Amos and Amos, 1991;Theriot and Mitchinson, 1991); for this reason, their change of position during spermatogenesis were studied in many vertebrates and invertebrates (Campanella et al, 1979;Desai et al, 2009;Dvo r akov a et al, 2005;Ghosh-Roy et al, 2005;Guerra and Esponda, 1999;Noguchi and Miller, 2003;P eknicov a et al, 2001;Phillips, 1970;Sahara and Kawamura, 2004;Sakai et al, 1993;Tinley et al, 1987;Trimmer and Vacquier, 1986;Virtanen et al, 1984;).…”

“…In the insects, once again, data regarding localization and displacements of both the cytoskeletal components during spermatogenesis is scarce and referred to very few species, such as Platycleis albopunctata (Guerra and Esponda, 1999), some species of the genus Drosophila (Ghosh-Roy et al, 2005;Noguchi and Miller, 2003) and Bombyx mori (Sahara and Kawamura, 2004); in the latter species, in particular, the dynamics of actin filaments appears to be the main mechanism of peristaltic squeezing of the sperm bundles.…”

Involvement of a gelsolin-related protein in spermatogenesis of the earthworm Lumbricus terrestris

“…In addition to microtubules, actin has been shown to be involved in sperm development in both vertebrate and invertebrate species, i.e. in arthropods, echinoderms and vertebrates (Guerra and Esponda 1999;Sherman et al 1999;Hime et al 1996;Tilney 1978;Ochs and Wolf 1985;Casale et al 1988). Several actin-binding proteins have been identified in spermatozoa: α-actinin (Yagi and Paranko 1992) and scinderin (Pelletier et al 1999) in bovines, a cofilin/ADF homologue in Drosophila (Gunsalus et al 1995) and profilin and fascin in Thyone (Tilney 1978;Maekawa et al 1982).…”