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Analysis of Hardening of the Egg Envelope (Chorion) of the Fish, Oryzias latipes
Author(s) -
Masuda Kaori,
Luchi Ichiro,
Yamagami Kenjiro
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.1991.00075.x
Subject(s) - ionophore , oryzias , solubility , hardening (computing) , chemistry , biophysics , biochemistry , biology , membrane , organic chemistry , layer (electronics) , gene
Hardening of the chorion of medaka eggs was quantitated in terms of the solubility of its constituent proteins. After activation of unfertilized eggs with the Ca 2+ ‐ionophore A23187, hardening of chorion (named ionophore‐activation hardening) proceeded and 60 min after activation the solubility of the proteins in 1 N NaOH had decreased to 20% of that of proteins of unhardened chorions. On SDS‐PAGE, the chorions of unfertilized eggs gave four major protein bands (150, 83, 78 and 51 K). After Ca 2+ ‐ionophore activation, new two protein bands (135 and 61 K) appeared, with concurrent disappearance of all the original bands except the 51 K band. Isolated chorions of unfertilized eggs were also hardened by Ca 2+ and 60 min after addition of Ca 2+ the solubility of their proteins in 1 N NaOH had decreased to about 45% of that originally. During this type of hardening (named ‘Ca 2+ ‐hardening), however, the SDS‐PAGE pattern of the proteins remained unchanged. Therefore, there are two mechanisms of hardening. The ‘ionophore‐activation hardening was inhibited by cadaverine. When chorions were isolated 20 min after Ca 2+ ‐ionophore activation and kept in Ca 2+ ‐free conditions, the ‘ionophore‐activation hardening process was arrested: further hardening was resumed on addition of Ca 2+ to the medium. These results suggest the presence of some hardening machinery in isolated chorions.