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Signaling pathway from [Ca 2+ ] i transients to ooplasmic segregation involves small GTPase rho in the ascidian egg
Author(s) -
Yoshida Manabu,
Horiuchi Yuji,
Sensui Noburu,
Morisawa Masaaki
Publication year - 2003
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 - 10.1046/j.1524-4725.2003.695.x
Subject(s) - cytokinesis , microbiology and biotechnology , actin , oocyte activation , biology , cleavage (geology) , cytoskeleton , intracellular , biophysics , chemistry , embryogenesis , biochemistry , embryo , cell division , cell , paleontology , fracture (geology)
Intracellular Ca 2+ transients occur at fertilization in the eggs of all animal species and are thought to be critical for the initiation of several events in egg activation. The rho family of small GTPases are known to organize and maintain the actin filament‐dependent cytoskeleton, and rho is involved in the control mechanism of cytokinesis. In the ascidian Ciona savignyi , the first step of ooplasmic segregation observed just after fertilization is cortical contraction with egg deformation, mediated by the cortical actin filaments. C3 exoenzyme, a rho‐specific inhibitor, did not affect the pattern of [Ca 2+ ] i transients in the ascidian egg, but inhibited ooplasmic segregation and cytokinesis at the first cleavage. Injection of inositol 1,4,5‐trisphosphate or treatment of Ca 2+ ionophore induced deformation of the egg and extrusion of the first polar body, but these phenomena did not occur in the C3 exoenzyme‐injected egg. These results suggest that rho proteins are involved in egg deformation, ooplasmic segregation and cytokinesis downstream of the [Ca 2+ ] i transients.