The ubiquitin-proteasome system is essential for intracellular protein degradation, but an extracellular role of this system has not been known until now. We have previously reported that the proteasome is secreted into the surrounding seawater from sperm of the ascidian (Urochordata) Halocynthia roretzi on sperm activation, and that the sperm proteasome plays a key role in fertilization. Here,...

Interaction of rapidly evolving molecules imparts species specificity to sperm-egg recognition in marine invertebrates, but it is unclear whether comparable interactions occur during fertilization in any vertebrate species. In mammals, the sperm acrosomal protein zonadhesin is a rapidly evolving molecule with species-specific binding activity for the egg zona pellucida (ZP). Here we show using ...

The amino terminus of the sperm cAMP-dependent protein kinase catalytic subunit (termed Cs) differs from that of the Ca1 isoform expressed in most tissues due to the use of alternative transcripts of the Ca gene. Both Ca1 and Cs transcripts are present in testis; Cs is expressed specifically in spermatogenic cells and is the only C isoform detected in mature sperm. Immunohistochemistry of mouse...

An oviduct-specific, estrus-associated glycoprotein (EAP) of 85-95 kDa is detectable in both conditioned medium (CM) from oviductal explants and cannula-derived oviductal fluid (ODF). The objectives of this study were to purify EAP from both ODF and CM, to characterize the glycosylation of EAP, and to localize binding of EAP on sperm. EAP was purified from ODF by ammonium sulfate precipitation ...

Acrosomal assembly during spermatogenesis and acrosome reaction during sperm-oocyte interaction are unique events of vesicle synthesis, transport, and fusion leading to fertilization. SNARE complex formation is essential for membrane fusion, and vesicle-associated (v-) SNARE intertwines with target membrane (t-) SNARE to form a coiled coil that bridges two membranes and facilitates fusion. We d...

The identification and characterization of germ cell-specific genes are essential if we hope to comprehensively understand the mechanisms of spermatogenesis and fertilization. Here, we searched the mouse UniGene databases and identified 13 novel genes as being putatively testis-specific or -predominant. Our in silico and in vitro analyses revealed that the expressions of these genes are testis-...

An adaptation of the Feulgen procedure to visualise DNA at the ultrastructural level, using osmium ammine instead of Schiff reagent, was applied to ultrathin sections of rabbit epididymal spermatozoa, known to display increasing chromatin compaction as they progress through the epididymis. In contrast with the somatic cell nuclei of the epididymal epithelium, which display classical staining, t...

There are several mechanisms acting in synergism that can impair sperm characteristics of patients with accessory gland infection. In some cases, conventional sperm variables are disturbed with oligo and/or asthenozoospermia. In other patients, these sperm variables may appear normal, but the functional capacity of spermatozoa may be impaired. In particular, changes in the composition of the sp...

Recent studies have identified Ca(2+) stores in sperm cells; however, it is not clear whether these Ca(2+) stores are functional and how they are mobilized. Here, in vitro and in vivo, we determined that tripeptidyl peptidase II antagonists strongly activated the cAMP/PKA signaling pathway that drives sperm capacitation-associated protein tyrosine phosphorylation. We demonstrated that in the ab...

The present study reports data on post-translational modifications in the glycosylation status during epididymal passage and significance in fertility of a 33 kDa glycoprotein of rhesus monkey (Macaca mulatta), designated as MEF3 (monkey epididymal fluid protein 3). MEF3 exhibited strong affinity for N-linked alpha-D-mannose groups and O-linked N-Ac-galactosamine linkages in epididymal fluids a...