Premium
Intracellular pH change does not accompany egg activation in the mouse
Author(s) -
Phillips Karen P.,
Baltz Jay M.
Publication year - 1996
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/(sici)1098-2795(199609)45:1<52::aid-mrd8>3.0.co;2-r
Subject(s) - germinal vesicle , biology , antiporter , oocyte activation , human fertilization , intracellular ph , zygote , sea urchin , oocyte , xenopus , microbiology and biotechnology , intracellular , in vivo , bicarbonate , biochemistry , embryo , embryogenesis , endocrinology , anatomy , genetics , membrane , gene
In the sea urchin, some other marine invertebrates, and the frog, Xenopus, egg activation at fertilization is accompanied by an increase in intracellular pH (pH i ). We measured pH i , in germinal vesicle (GV)‐intact mouse oocytes, ovulated eggs, and in vivo fertilized zygotes using the pH indicator dye, SNARF‐1. The mean pH i was 6.96 ± 0.004 (± SEM) in GV‐intact oocytes, 7.00 ± 0.01 in ovulated, unfertilized eggs, and 7.02 ± 0.01 in fertilized zygotes, indicating no sustained changes in pH i after germinal vesicle breakdown (GVBD) or fertilization. To examine whether transient changes in pH i occur shortly after egg activation, mouse eggs were parthenogenetically activated by 7% ethanol in phosphate buffered saline (PBS); no significant change in pH i followed ethanol activation. Since increased Na + /H + antiporter activity is responsible for pH i increase in the sea urchin, pH i was measured in the absence of added bicarbonate or CO 2 la condition under which the antiporter would be the only major pH i regulatory mechanism able to operate, since the others were bicarbonate‐ dependent) in GV‐intact oocytes, ovulated eggs, and in vivo fertilized zygotes to determine whether a Na + /H + antiporter was activated. There was no physiologically significant difference in pH i after GVBD or fertilization, when pH i was measured in bicarbonate‐free medium, nor any change upon parthenogenetic activation. Thus, a change in pH i is not a feature of egg activation in the mouse. © 1996 Wiley‐Liss, Inc.