Zona pellucida-mediated acrosomal exocytosis in mouse spermatozoa: characterization of an intermediate stage prior to the completion of the acrosome reaction

Dev Biol. 1991 Jun;145(2):344-55. doi: 10.1016/0012-1606(91)90133-n.

Abstract

The zona pellucida (ZP)-induced acrosome reaction in mouse sperm proceeds in two steps, identified by three sperm fluorescence patterns observed sequentially with the fluorescent probe chlortetracycline. Capacitated, acrosome-intact sperm displaying a B pattern proceed to an intermediate S pattern, and then progress from the S pattern to the fully acrosome-reacted AR pattern. Previously, it was not feasible to characterize the nature of the transient intermediate S pattern. Recently, it was demonstrated that sperm bind to the ZP of eggs treated with 12-O-tetradecanoyl phorbol-13-acetate (TPA) and undergo a B to S transition, but do not complete the acrosome reaction. These cells accumulate in the S pattern and fail to undergo the S to AR transition (Endo, Y., Schultz, R. M., and Kopf, G. S. 1987a. Dev. Biol. 119, 119-209). The present study utilized ZP from TPA-treated eggs to assess the state of S pattern sperm. The kinetics of the B to S transition of sperm incubated with either structurally intact or solubilized ZP from untreated or TPA-treated eggs are identical. Addition of either solubilized ZP from untreated eggs or A-23187 to S pattern sperm bound to intact or solubilized ZP from TPA-treated eggs induces the S to AR transition, while ZP from TPA-treated or fertilized eggs does not. Loss of the transmembrane pH gradient in the anterior portion of the sperm head, monitored by the fluorescent pH probe 9-N-dodecyl aminoacridine, follows the B to S transition in sperm incubated with ZP from unfertilized eggs, but no loss is observed when the B to S transition is induced using ZP from TPA-treated eggs. Subsequent addition of solubilized ZP from untreated eggs or A-23187 results in the loss of the transmembrane pH gradient of these S pattern sperm. Addition of nigericin to S pattern sperm bound to ZP from TPA-treated eggs discharges the transmembrane pH gradient and causes the S to AR transition. In contrast, nigericin added to B pattern sperm discharges the pH gradient but does not induce a B to S transition. Electron microscopic evaluation of S pattern-arrested sperm using ZP from TPA-treated eggs reveals intact plasma and outer acrosomal membranes. These results suggest that ZP from TPA-treated and fertilized eggs are modified such that the ZP ligands inducing the S to AR transition are lost or are inactivated.(ABSTRACT TRUNCATED AT 400 WORDS)

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acrosome / drug effects
  • Acrosome / physiology*
  • Animals
  • Calcimycin / pharmacology
  • Cell Membrane Permeability
  • Chlortetracycline
  • Exocytosis*
  • Female
  • Fluorescent Antibody Technique
  • Hydrogen-Ion Concentration
  • In Vitro Techniques
  • Male
  • Microscopy, Electron
  • Nigericin / pharmacology
  • Rats
  • Sperm Capacitation
  • Sperm-Ovum Interactions / drug effects
  • Sperm-Ovum Interactions / physiology*
  • Tetradecanoylphorbol Acetate / pharmacology
  • Time Factors
  • Zona Pellucida / physiology*

Substances

  • Calcimycin
  • Tetradecanoylphorbol Acetate
  • Nigericin
  • Chlortetracycline