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Intracellular pH Changes of Starfish Sperm Upon the Acrosome Reaction
Author(s) -
MATSUI TAEI,
NISHIYAMA ICHIRO,
HINO AKIYA,
HOSHI MOTONORI
Publication year - 1986
Publication title -
development, growth and differentiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.864
H-Index - 66
eISSN - 1440-169X
pISSN - 0012-1592
DOI - 10.1111/j.1440-169x.1986.00359.x
Subject(s) - acrosome reaction , pronase , intracellular ph , sperm , chemistry , starfish , intracellular , biophysics , biochemistry , ionophore , acrosome , chromatography , biology , trypsin , botany , in vitro , enzyme , membrane , ecology
The acrosome reaction is accompanied by ionic changes such as increases in intracellular Ca 2+ and intracellular pH (pH i ). Since the two jelly components essential for inducing the acrosome reaction, ARIS and Co‐ARIS, were shown to activate Ca‐channels (accompanying paper), we examined the jelly components to determine which was responsible for the pH i ‐increase using 9‐aminoacridine as a probe of pH i . This paper presents evidence that an oligopeptide(s) is responsible for the pH i ‐increase. The pH i of swimming sperm is 7.4‐7.5. Within 20 sec after the addition of jelly, their pH i increased rapidly by 0.06 pH unit, then decreased by 0.2–0.3 pH unit, and reached a plateau level within 3 min. Similar changes in pH i were observed on addition of a Pronase digest of ARIS (P‐ARIS) and a diffusible fraction of jelly (Fraction M 8 ) together. Fraction M 8 , but not ARIS or Co‐ARIS increased the pH i , and activated sperm respiration in sea water at pH 6.5. The two activities of Fraction M 8 depended upon Na + but not Ca 2+ , and were susceptible to Pronase digestion. Fraction M 8 is also known to enhance induction of the acrosome reaction by the Ca‐ionophore A23187. These results suggest that the egg jelly contains a peptide(s) that is not obligatory for the acrosome reaction but facilitates the reaction by increasing the pH i of the sperm. The significance of the pH i ‐increase upon the acrosome reaction is discussed.