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Mitochondrial inhibitor sodium azide inhibits the reorganization of mitochondria‐rich cytoplasm and the establishment of the anteroposterior axis in ascidian embryo
Author(s) -
Ishii Hirokazu,
Shirai Takuma,
Makino Chisato,
Nishikata Takahito
Publication year - 2014
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/dgd.12117
Subject(s) - cytoplasm , microbiology and biotechnology , biology , microtubule , mitochondrion , sperm , sodium azide , advanced spaceborne thermal emission and reflection radiometer , embryo , biophysics , biochemistry , botany , remote sensing , geology , digital elevation model
In ascidian eggs, cytoplasmic and cortical reorganization, previously called ooplasmic segregation, occurs in two phases during the first cell cycle. In the second phase of reorganization, the mitochondria‐rich cytoplasm (myoplasm) moves to the future posterior side, concurrent with sperm aster migration along the egg cortex. Although this reorganization is the critical step for establishing the anteroposterior axis, its molecular mechanism is not fully understood. In this study, we showed that low concentrations of the mitochondrial inhibitor sodium azide (NaN 3 ), which showed the low toxicity in sperm, inhibited the second phase of reorganization without the microtubule depolymerization. In the NaN 3 ‐treated embryo, the sperm aster was not attracted to the cortex and altered its migration pathway; therefore, the myoplasm remained at the vegetal pole. Consequently, the anteroposterior axis was not established. Another mitochondrial inhibitor, oligomycin, did not affect these processes. These results suggest that NaN 3 inhibits unknown molecules that are important for the second phase of reorganization. Identifying the target molecule of NaN 3 will lead to a molecular understanding of cytoplasmic and cortical reorganization.