Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 7-Day Trial for You or Your Team.

Learn More →

Regulation of Intracellular Calcium in the Mouse Egg: Calcium Release in Response to Sperm or Inositol Trisphosphate is Enhanced after Meiotic Maturation

Regulation of Intracellular Calcium in the Mouse Egg: Calcium Release in Response to Sperm or... Abstract Fertilization of the immature, prophase I-arrested mouse oocyte produces multiple Ca2+ transients similar to those of the mature, metaphase II egg; however, the first Ca2+ transient is much lower in amplitude and shorter in duration. In contrast to prophase I-arrested oocytes, maturing oocytes fertilized after germinal vesicle breakdown have first Ca2+ transients similar to those of mature fertilized eggs. Immature, prophase-arrested oocytes release less Ca2+ in response to injection of inositol 1,4,5-trisphosphate (IP3) than eggs. At high concentrations, the sulfhydryl reagent, thimerosal (200 μM), causes Ca2+ oscillations in eggs and produces similar oscillations in oocytes. A lower concentration of thimerosal (25 μM) does not cause Ca2+ oscillations, but does sensitize IP3-induced Ca2+ release in both eggs and oocytes, since IP3-induced Ca2+ release is enhanced in the presence of 25 μM thimerosal. Incubation of oocytes in 25 μM thimerosal before injection of 2.2 μM IP3 causes oocytes to release as much Ca2+ as is released in eggs injected with 2.2 μM IP3. These results indicate that immature mouse oocytes possess intracellular stores of releasable Ca2+ similar in size to Ca2+ stores in eggs; however, these stores are less sensitive to IP3. Development of the IP3-induced Ca2+ release mechanism may be an important component of maturation; at fertilization of the egg, Ca2+ must be elevated to levels sufficient to activate further development and establish a block to polyspermy. Mouse oocytes appear to develop an increased sensitivity to IP3 during the course of oocyte maturation. This content is only available as a PDF. Author notes 1 This work was supported by a grant from The Research Council of Kent State University and NIH grant RR07208. Copyright © 1994 by The Society for the Study of Reproduction http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Biology of Reproduction Oxford University Press

Regulation of Intracellular Calcium in the Mouse Egg: Calcium Release in Response to Sperm or Inositol Trisphosphate is Enhanced after Meiotic Maturation

Download PDF
11 pages

Loading next page...
 
/lp/oxford-university-press/regulation-of-intracellular-calcium-in-the-mouse-egg-calcium-release-XJiV52Q2ir

References (61)

Publisher
Oxford University Press
Copyright
Copyright © 1994 by The Society for the Study of Reproduction
ISSN
0006-3363
eISSN
1529-7268
DOI
10.1095/biolreprod51.6.1088
Publisher site
See Article on Publisher Site

Abstract

Abstract Fertilization of the immature, prophase I-arrested mouse oocyte produces multiple Ca2+ transients similar to those of the mature, metaphase II egg; however, the first Ca2+ transient is much lower in amplitude and shorter in duration. In contrast to prophase I-arrested oocytes, maturing oocytes fertilized after germinal vesicle breakdown have first Ca2+ transients similar to those of mature fertilized eggs. Immature, prophase-arrested oocytes release less Ca2+ in response to injection of inositol 1,4,5-trisphosphate (IP3) than eggs. At high concentrations, the sulfhydryl reagent, thimerosal (200 μM), causes Ca2+ oscillations in eggs and produces similar oscillations in oocytes. A lower concentration of thimerosal (25 μM) does not cause Ca2+ oscillations, but does sensitize IP3-induced Ca2+ release in both eggs and oocytes, since IP3-induced Ca2+ release is enhanced in the presence of 25 μM thimerosal. Incubation of oocytes in 25 μM thimerosal before injection of 2.2 μM IP3 causes oocytes to release as much Ca2+ as is released in eggs injected with 2.2 μM IP3. These results indicate that immature mouse oocytes possess intracellular stores of releasable Ca2+ similar in size to Ca2+ stores in eggs; however, these stores are less sensitive to IP3. Development of the IP3-induced Ca2+ release mechanism may be an important component of maturation; at fertilization of the egg, Ca2+ must be elevated to levels sufficient to activate further development and establish a block to polyspermy. Mouse oocytes appear to develop an increased sensitivity to IP3 during the course of oocyte maturation. This content is only available as a PDF. Author notes 1 This work was supported by a grant from The Research Council of Kent State University and NIH grant RR07208. Copyright © 1994 by The Society for the Study of Reproduction

Journal

Biology of Reproduction – Oxford University Press

Published: Dec 1, 1994

There are no references for this article.