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Sperm storage influences the potential for spontaneous acrosome reaction of the sperm in the newt Cynops pyrrhogaster
Author(s) -
Kon Shinnosuke,
Sato Tae,
Endo Daisuke,
Takahashi Tomoe,
Takaku Akio,
Nakauchi Yuni,
Toyama Fubito,
MeyerRochow Victor B.,
TakayamaWatanabe Eriko,
Watanabe Akihiko
Publication year - 2017
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/mrd.22932
Subject(s) - acrosome reaction , sperm , vas deferens , acrosome , andrology , biology , medicine , endocrinology , chemistry
Sperm storage is supposed to influence sperm quality, although the details remain unclear. In the present study, we found that sperm stored in a sperm storage site, the vas deferens of Cynops pyrrhogaster , spontaneously undergo acrosome reaction following incubation in Steinberg's salt solution (ST). Percentages of acrosome‐reacted sperm increased time‐dependently to about 60% in 24 hr. The concentration of cyclic adenosine monophosphate (cAMP) was elevated after incubating sperm in ST, while dibutylyl cAMP induced an acrosome reaction. Chelating of extracellular Ca 2+ suppressed the dibutylyl cAMP‐induced acrosome reaction as well as spontaneous acrosome reaction in ST. These results suggest that cAMP elevation driven by Ca 2+ influx can be a cue for spontaneous acrosome reaction. Relatively low Ca 2+ concentration and pH in the vas deferens were sufficient to suppress spontaneous acrosome reaction within 1 hr. In addition, the cysteine rich secretory protein 2 gene was expressed in the vas deferens, indicating that it may be involved in the continuous suppression of spontaneous acrosome reaction. Sperm that underwent spontaneous acrosome reaction in ST was significantly increased when stored in the vas deferens for longer periods, or by males experiencing temperatures in excess of 12°C during hibernation conditions. Percentages of the spontaneously acrosome‐reacted sperm were found to differ among males even though they were of identical genetic background. Taken together, C. pyrrhogaster sperm possess the potential for spontaneous acrosome reaction that does not become obvious in the vas deferens, unless promoted in correlation with sperm storage.