Separation of calcium effects on motility and zona binding ability in mouse spermatozoa

✍ Scribed by Heffner, Linda J. ;Sailing, Patricia M. ;Storey, Bayard T.

• Publisher: John Wiley and Sons
• Year: 1980
• Tongue: English
• Weight: 654 KB
• Volume: 212
• Category: Article
• ISSN: 0022-104X
• DOI: 10.1002/jez.1402120108

✦ Synopsis

Abstract

The ionic specificity of Ca^+2^ requirements for binding to the zona pellucida and maintenance of motility were studied in mouse gametes by comparing the effects of four cations: Ca^+2^, Sr^+2^, La^+3^, and spermine cation (Sp^+4^). Cumulus‐free mouse eggs were inseminated in vitro with sperm which had been preincubated for 60 min in Tris‐NaCl buffer containing one or more of the above cations. Motility was assessed microscopically and zona binding, by the stop‐fix technique, utilizing centrifugation through a discontinuous density gradient. The sperm were motile upon release from the epididymis, and all sperm maintained their motility in complete culture medium. Sperm incubated in Tris‐NaCl buffer differed in motility among samples as follows: The majority of sperm samples remained motile in Tris‐NaCl containing 1.7 mM Ca^+2^, but lost motility if Ca^+2^ was absent. The remaining samples could be divided into two populations: those which maintained motility in the absence of Ca^+2^. Support of Zona binding required Ca^+2^ in all samples examined. Equimolar Sr^+2^ could substitute for Ca^+2^ in maintaining motility but not in supporting binding. Sp^+4^and La^+3^ did not support motility. If Sr^+2^ were present to maintain motility, both Sp^+4^ and La^+3^ supported binding as well as Ca^+2^. Sr^+2^ did not complete with any of the other cations for support of zona binding. Ca^+2^ and Sp^+4^ together in the medium produced a synergism in the number of sperm bound. La^+3^ would substitute for Ca^+2^ in this synergism. These results demonstrate for the first time that mouse sperm have Ca^+2^ requirement for the motility maintenance and that binding to the zona and maintenance of motility are two different Ca^+2^‐dependent processes whose active sites can be distinguished by cation substitution.