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Functional Characterization of G12, a Gene Required for Mitotic Progression during Gastrulation in ZebrafishIn a differential RNA display screen we have isolated a zebrafish gene, G12, for which homologs can only be found in DNA databases for vertebrates, but not invertebrates. This suggests that this is a gene required specifically in vertebrates. G12 expression is upregulated at mid-blastula transition (MBT). Morpholino inactivation of this gene by injection into 1-cell embryos results in mitotic defects and apoptosis shortly after MBT. Nuclei in morpholino treated embryos also display segregation defects. We have characterized the localization of this gene as a GFP fusion in live and fixed embryos. Overexpression of G12-GFP is non-toxic. Animals retain GFP expression for at least 7 days with no developmental defects, Interestingly in these animals G12-GFP is never detectable in blood cells though blood is present. In the deep cells of early embryos, G 12GFP is localized to nuclei and cytoskeletal elements in interphase and to the centrosome and spindle apparatus during mitosis. In the EVL, G12-GFP shows additional localization to the cell periphery, especially in mitosis. In the yolk syncytium, G12-GFP again localizes to nuclei and strongly to cytoplasmic microtubules of migrating nuclei at the YSL margin. Morpholinc, injection specifically into the YSL after cellularization blocks epiboly and nuclei of the YSL show mitotic defects while deep cells show no mitotic defects and continue to divide. Rescue experiments in which morpholino and G12-GFP RNA are co-injected indicate partial rescue by the G12-GFP. The rescue is cell autonomous; that is, regions of the embryo with higher G12-GFP expression show fewer mitotic defects. Spot 14, the human bomolog of G12, has been shown to be amplified in aggressive breast tumors. This finding, along with our functional and morphological data suggest that G12 and spot 14 are vertebrate-specific and may function either as mitotic checkpoints or as structural components of the spindle apparatus.
Document ID
20020064457
Acquisition Source
Ames Research Center
Document Type
Conference Paper
Authors
Reinsch, Sigrid
(NASA Ames Research Center Moffett Field, CA United States)
Conway, Gregory
(NASA Ames Research Center Moffett Field, CA United States)
Dalton, Bonnie P.
Date Acquired
August 20, 2013
Publication Date
January 1, 2002
Subject Category
Life Sciences (General)
Meeting Information
Meeting: West Coast Regional Developmental Biology Meeting
Location: Bodega Bay, CA
Country: United States
Start Date: March 1, 2002
End Date: March 3, 2002
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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