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Change in Intracellular Calcium Ions upon Maturation in Starfish Oocytes
Author(s) -
Kikuyama Munehiro,
Hiramoto Yukio
Publication year - 1991
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.1991.00633.x
Subject(s) - starfish , calcium , intracellular , biophysics , chemistry , calcium in biology , microbiology and biotechnology , biology , biochemistry , ecology , organic chemistry
A transient increase in intracellular Ca 2+ upon maturation in starfish oocyte was revealed by light emission of aequorin microinjected into the cell. One minute application of 1‐methyladenine (1‐MeAde) to a limited area of the oocyte surface was sufficient to induce the Ca 2+ transient over the entire cell though it did not induce the germinal vesicle breakdown (GVBD). Ten minutes application of 1‐MeAde induced a similar Ca 2+ transient followed by GVBD. Even when the transient increase of Ca 2+ was inhibited by injecting EGTA into the oocyte, 1‐MeAde treatment for a long period induced GVBD. These facts indicate that the Ca 2+ increase is neither necessary nor sufficient for maturation of the starfish oocyte. When the oocyte, which had been treated with 1‐MeAde for 1 min at a limited area around the animal pole, was treated again with 1‐MeAde for 10 min starting about 15 min after the first treatment, a Ca 2+ transient similar to the first one was induced and was followed by GVBD. By contrast, in the oocyte treated with 1‐MeAde at an area around the vegetal pole, neither Ca 2+ transient nor GVBD was induced by the second treatment with 1‐MeAde. These results indicate a difference in responsiveness to the hormone between the animal hemisphere and the vegetal hemisphere of the oocyte.