TY - JOUR
T1 - Maternal effect mutations of the sponge locus affect actin cytoskeletal rearrangements in Drosophila melanogaster embryos
AU - Postner, M. A.
AU - Miller, K. G.
AU - Wieschaus, E. F.
PY - 1992
Y1 - 1992
N2 - In the syncytial blastoderm stage of Drosophila embryogenesis, dome-shaped actin 'caps' are observed above the interphase nuclei. During mitosis, this actin rearranges to participate in the formation of pseudocleavage furrows, transient membranous invaginations between dividing nuclei. Embryos laid by homozygous sponge mothers lack these characteristic actin structures, but retain other actin associated structures and processes. Our results indicate that the sponge product is specifically required for the formation of actin caps and metaphase furrows. The specificity of the sponge phenotype permits dissection of both the process of actin cap formation and the functions of actin caps and metaphase furrows. Our data demonstrate that the distribution of actin binding protein 13D2 is unaffected in sponge embryos and suggest that 13D2 is upstream of actin in cortical cap assembly. Although actin caps and metaphase furrows have been implicated in maintaining the fidelity of nuclear division and the positions of nuclei within the cortex, our observations indicate that these structures are dispensible during the early syncytial blastoderm cell cycles. A later requirement for actin metaphase furrows in preventing the nucleation of mitotic spindles between inappropriate centrosomes is observed. Furthermore, the formation of actin caps and metaphase furrows is not a prerequisite for the formation of the hexagonal array of actin instrumental in the conversion of the syncytial embryo into a cellular blastoderm.
AB - In the syncytial blastoderm stage of Drosophila embryogenesis, dome-shaped actin 'caps' are observed above the interphase nuclei. During mitosis, this actin rearranges to participate in the formation of pseudocleavage furrows, transient membranous invaginations between dividing nuclei. Embryos laid by homozygous sponge mothers lack these characteristic actin structures, but retain other actin associated structures and processes. Our results indicate that the sponge product is specifically required for the formation of actin caps and metaphase furrows. The specificity of the sponge phenotype permits dissection of both the process of actin cap formation and the functions of actin caps and metaphase furrows. Our data demonstrate that the distribution of actin binding protein 13D2 is unaffected in sponge embryos and suggest that 13D2 is upstream of actin in cortical cap assembly. Although actin caps and metaphase furrows have been implicated in maintaining the fidelity of nuclear division and the positions of nuclei within the cortex, our observations indicate that these structures are dispensible during the early syncytial blastoderm cell cycles. A later requirement for actin metaphase furrows in preventing the nucleation of mitotic spindles between inappropriate centrosomes is observed. Furthermore, the formation of actin caps and metaphase furrows is not a prerequisite for the formation of the hexagonal array of actin instrumental in the conversion of the syncytial embryo into a cellular blastoderm.
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U2 - 10.1083/jcb.119.5.1205
DO - 10.1083/jcb.119.5.1205
M3 - Article
C2 - 1447298
AN - SCOPUS:0026446698
SN - 0021-9525
VL - 119
SP - 1205
EP - 1218
JO - Journal of Cell Biology
JF - Journal of Cell Biology
IS - 5
ER -