Actin polymerisation during morphogenesis of the acrosome as spermatozoa undergo epididymal maturation in the tammar wallaby (Macropus eugenii)

Abstract

In the tammar wallaby (Macropus eugenii), post-testicular acrosomal shaping involves a complex infolding and fusion of the anterior and lateral projections of the scoop-shaped acrosome into a compact button-like structure occupying the depression on the anterior end of the sperm nucleus. The present study has generated cytochemical and histological evidence to demonstrate that the occurrence of actin filaments (F-actin, labelled by Phalloidin-FITC) in the acrosome of tammar wallaby spermatozoa is temporally and spatially associated with the process of acrosomal shaping in the epididymis, through a pool of monomeric actin (G-actin, labelled by Rh-DNase I) present in the acrosome throughout all stages of epididymal maturation. F-actin was not detected in the acrosome of testicular spermatozoa, but was found in the infolding and condensing acrosome of caput and corpus epididymal spermatozoa. When the spermatozoa completed acrosome shaping in the cauda epididymidis, F-actin disappeared from the acrosomal area. The strong correlation between the occurrence of F-actin and the events of acrosomal shaping suggested that the post-testicular shaping of the acrosome might depend on a precise succession of assembly and disassembly of F-actin within the acrosome as the spermatozoa transit the epididymis. Thus, actin filaments might play a significant role in the acrosomal transformation, as they are commonly involved in morphological changes in somatic cells.

Head and flagella subcompartmental proteomic analysis of human spermatozoa

“…In a similar manner, the head fraction was demonstrated to be very pure. Highly abundant, known head proteins included calicin (spectral counts 67 head: 1 tail), actin (spectral counts 16 head: 0 tail) and the majority of the 26s proteasome subunits , all of which are known to compartmentalize in the head region. Nevertheless, some minor contamination did exist, e.g.…”

The Phospholipid Composition of Kangaroo Spermatozoa Verified by Mass Spectrometric Lipid Analysis

“…Condensation of the nuclear content leads to a post-testicular T-shaped appearance of the sperm head. During the epididymal transit a striking reorganization of the acrosome occurs, and the kangaroo sperm head aligns parallel to the longitudinal axis of the flagellum, presumably by a precise succession of assembly and disassembly of F-actin [4]. In 2004 Miller Jr. and colleagues published their results on the fatty acyl composition of caput and cauda sperm membranes of the eastern grey kangaroo (Macropus giganteus), the koala (Phascolarctos cinereus), and the common wombat (Vombatus ursinus).…”

The novel, actin‐like protein Tact3 is expressed in rodent testicular haploid germ cells

“…Actin proteins, actin‐associated proteins, and diverse cell‐adhesion molecules are involved in spermiogenesis, as evidenced by the fact that actin proteins are present in the perinuclear region or subacrosomal space of sperm (Fouquet and Kann, ; Lecuyer et al, ; Scarlett et al, ; Lie et al, ). Actin is important for spermiogenesis (Scarlett et al, ), and actin‐related molecules play major roles in shaping sperm morphology (Lecuyer et al, ; Lie et al, ; Miller, ). Although cytoplasmic actins are expressed at all stages of germ‐cell differentiation, developmentally regulated expression of actin and actin‐related proteins indicates that they are involved in the differentiation of haploid germ cells.…”