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Porcine oocyte activation: Differing roles of calcium and pH
Author(s) -
Ruddock Nancy T.,
Macháty Zoltán,
Cabot Ryan A.,
Prather Randall S.
Publication year - 2001
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.1027
Subject(s) - bapta , calcium , oocyte activation , calcium in biology , intracellular , oocyte , biology , dithiothreitol , pronucleus , andrology , endocrinology , biophysics , microbiology and biotechnology , medicine , biochemistry , embryogenesis , embryo , zygote , enzyme
Intracellular pH has recently been shown to increase during parthenogenetic activation of the porcine oocyte. In the following set of experiments, intracellular pH was monitored during activation and pronuclear development was assessed following activation treatments with calcium, in the absence of calcium, and in oocytes loaded with the calcium chelator BAPTA‐AM in calcium‐free medium. Intracellular pH increase was not different among groups when treating with 7% ethanol or 50 μM calcium ionophore, or during treatment with thimerosal for 12 or 25 min. Activation with thimerosal (200 μM, 12 min) followed by 8 mM dithiothreitol (DTT, 30 min) resulted in a decreased pronuclear development in calcium‐free medium with or without BAPTA‐AM loaded oocytes as compared to controls. Activation with 50 μM calcium ionophore resulted in pronuclear development that was different between the calcium‐free and BAPTA‐AM loaded oocytes in calcium‐free medium. Similar incidences of pronuclear formation were observed in all ethanol treatment groups. It was concluded that external calcium as well as large changes in intracellular free calcium are not necessary for the increase in intracellular pH, but normal intracellular calcium signaling is critical for normal levels of pronuclear development. Finally, oocytes were measured for intracellular pH changes for 30 min following subzonal sperm injection. Intracellular pH did not increase, although pronuclear formation was observed 6 hr post SUZI. This suggested that major differences were still present between sperm‐induced and parthenogenetic activation of the porcine oocyte. Mol. Reprod. Dev. 59:227–234, 2001. © 2001 Wiley‐Liss, Inc.