Electrically induced calcium elevation, activation, and parthenogenetic development of bovine oocytes
- 1 February 1993
- journal article
- research article
- Published by Wiley in Molecular Reproduction and Development
- Vol. 34 (2), 212-223
- https://doi.org/10.1002/mrd.1080340214
Abstract
The influence of electrical stimulation on the level of intracellular Ca2+ in bovine oocytes, as well as activation and extent of parthenogenetic development, was investigated. Mature oocytes were electrically stimulated at 29 hr of maturation, and intracellular Ca2+ concentration was determined with the Ca2+ indicator fura-2 dextran (fura-2 D). The Ca2+ response of oocytes to a given electrical pulse was variable. Oocytes responded with either no Ca2+ rise from baseline (≈︁ 12 nM), a short-duration Ca2+ rise (from 12 nM to 300 nM) that returned to baseline within 2 min of the pulse, or a long-duration Ca2+ rise (from 12 nM to 1,000–2,000 nM) that never returned to baseline during the 8 min period over which the oocytes were monitored. In these oocytes, Ca2+ level returned to baseline when oocytes were removed from 0.30 M mannitol and placed in an ionic medium. Increasing field strength or pulse duration tended to increase the proportion of oocytes displaying a Ca2+ rise, and at 1.0 kVcm−1 for 40 μsec, all oocytes displayed a long-duration Ca2+ elevation. Direct transfer of oocytes from culture medium to mannitol also triggered a Ca2+ rise. Multiple stimulations, either electrical or by transferring to mannitol, produced multiple Ca2+ rises. This mannitol-induced Ca2+ rise could be inhibited by first washing the oocytes in medium containing equal parts of 0.30 M mannitol and phosphate buffered saline (PBS). The level of Ca2+ stimulation affected activation and development of oocytes. Insufficient, or, conversely, excessive Ca2+ stimulation impaired development. Optimum development was obtained with (1) three pulses of 0.2 kVcm−1 for 20 μsec, each pulse 22 min apart, after direct transfer of oocytes from culture medium to mannitol (22% blastocysts) or (2) three pulses of 1.0 kVcm−1 for 20 μsec after transfer of oocytes from culture medium to medium containing equal parts mannitol and PBS, then to mannitol (24% blastocysts). This procedure avoided induction of a Ca2+ rise prior to the pulse. The results indicate that the level of Ca2+ stimulation can be regulated by incubation conditions prior to the pulse and, to some extent, by field strength and pulse duration. The level of electrical stimulation influenced oocyte Ca2+ response, activation, and parthenogenetic development.Keywords
This publication has 35 references indexed in Scilit:
- Repetitive calcium stimuli drive meiotic resumption and pronuclear development during mouse oocyte activationDevelopmental Biology, 1992
- Electrofusion‐induced intracellular Ca2+ flux and its effect on murine oocyte activationMolecular Reproduction and Development, 1992
- Repetitive calcium transients and the role of calcium in exocytosis and cell cycle activation in the mouse eggDevelopmental Biology, 1992
- Relationship between Nuclear Remodeling and Development in Nuclear Transplant Rabbit Embryos1Biology of Reproduction, 1991
- Repetitive calcium transients in hamster oocytesCell Calcium, 1991
- Spontaneous calcium influx and its roles in differentiation of spinal neurons in cultureDevelopmental Biology, 1990
- Age dependence of bovine oocyte activationGamete Research, 1989
- Parthenogenetic activation of cattle follicular oocytes in vitro with ethanolGamete Research, 1987
- Insemination of rabbit eggs is associated with slow depolarization and repetitive diphasic membrane potentialsDevelopmental Biology, 1983
- Electric field-induced cell-to-cell fusionThe Journal of Membrane Biology, 1982