Analysis of Mouse Oocyte Activation Suggests the Involvement of Sperm Perinuclear Material1

Abstract

The mouse oocyte can be activated by injection of a single, intact mouse spermatozoon or its isolated head. Isolated tails are unable to activate the oocyte. Active sperm-borne oocyte-activating factor(s) (SOAF) appears during transformation of the round spermatid into the spermatozoon. The action of SOAF is not highly species-specific: mouse oocytes are activated by injection of spermatozoa from foreign species, such as the hamster, rabbit, pig, human, and even fish. Some SOAF can be extracted by simple freeze-thawing of (hamster) spermatozoa; additional SOAF is obtained by sequential treatment of spermatozoa with Triton X-100 and SDS. Electron microscopic examination of sperm heads during SOAF extraction suggests that the relatively insoluble SOAF is associated with perinuclear material. When microsurgically injected into oocytes, Triton X-100-treated sperm heads (with perinuclear material, but without any membranes) can activate the oocytes, leading to normal embryonic development. Whereas perinuclear components have been believed to play a purely structural role, these data suggest an additional function for them in oocyte activation.

Mammalian Fertilization: From Sperm Factor to Phospholipase Cζ

“…Third, depletion of PLCf from hamster sperm extracts with a specific antibody largely removed the ability of these extracts to initiate [Ca 2+ ] i oscillations in mouse eggs (Lawrence et al, 1997;Jones et al, 1998b). In this context, it should be noted that the presence of PLCf has only been demonstrated in soluble sperm fractions , and it is now well established that significant amounts of [Ca 2+ ] i oscillationinducing activity are left associated with sperm heads after removal of soluble sperm extracts by common extraction procedures, such as sonication, freeze/thaw, or Triton X-100 treatment (Kimura et al, 1998;Perry et al, 2000;Kurokawa and Fissore, 2003). Therefore, it will be important to ascertain whether PLCf is present in both soluble and insoluble sperm fractions.…”

Somatic Histones Are Components of the Perinuclear Theca in Bovine Spermatozoa

“…Rather, the PT contains a range of proteins of varying function, including Calicin, a basic structural protein that binds actin (4,5); Stat4, a transcriptional activator hypothesized to contribute to zygotic gene activation (6); SubH2Bv (PT15), a histone H2B-like variant proposed to contribute to acrosome-nuclear docking (3); and PERF 15, a fatty acid-binding protein predominating in the perforatorium of murid sperm (7)(8)(9). The PT structure has been implicated in a number of essential cellular processes, such as nuclear shaping during spermiogenesis (2, 10), and egg activation and pronuclear formation during fertilization (11)(12)(13)(14)(15), although the PT proteins involved in these processes remain elusive. Their identification and characterization is therefore critical for understanding the mechanisms involved in these, and potentially other, important cellular processes.…”

Pronuclear formation of freeze-dried canine spermatozoa microinjected into mouse oocytes

“…1). Kimura et al [24] demonstrated that sperm perinuclear material contained a necessary substance (sperm-borne oocyte activating factor: SOAF) to activate the oocytes, and that the SOAF activity could be analyzed using mouse oocytes. As shown in Table 1, it seems that the SOAF activity in canine spermatozoa was not species-specific, and was maintained even when the spermatazoa were freezedried.…”

“…Activation of oocytes by sperm, subsequent formation of male pronucleus (MPN) and their chromosomal integrity can be considered as indicators for fertilizing ability of spermatozoa. Furthermore, these indicators can be monitored by microinjection into mouse oocytes in mouse [24,25], whale [26] and human [27,28] spermatozoa.…”