DIE-1
Supplemental material for the following paper:
Heid, P.J., Raich, W.B., Smith, R., Mohler, W.A., Simokat, K., Gendreau, S.B., Rothman, J.H., and Hardin, J. (2001). The zinc finger protein DIE-1 is required for late events during epithelial cell rearrangement in C. elegans. Dev Biol 236, 165-180. PubMed
Video sequence 1: Dorsal intercalation in wild-type and die-1 embryos visualized using Nomarski microscopy
In wild-type embryos, dorsal intercalation is highly reproducible from embryo to embryo. The process can visualized using Nomarski microscopy. Cells become wedge-shaped as they begin intercalation, and eventually adopt a ladder-like arrangement straddling the dorsal midline. In contrast to wild-type embryos, intercalation is defective in homozygous die-1 (w34) embryos. Note that many of the anterior dorsal hypodermal cells intercalate, but most of the posterior dorsal cells are wedged and do not intercalate completely before they fuse into the dorsal hypodermal syncytium. A = anterior; P = posterior. Dorsal views.
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Video sequence 2: Dorsal intercalation in wild-type embryos visualized using ajm-1::gfp
The process of dorsal intercalation can also be visualized using a translational fusion between the ajm-1 coding region (ajm = apical junctional molecule) and gfp. The embryo on the left (embryo #1) is anterior up; the embryo on the right (embryo #2) is anterior down. At the beginning of the sequence, cells in the posterior region of embryo #1 are wedging between one another. The “pointer cells” in the anterior (Williams-Masson et al., 1998) have not yet begun to wedge.
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Video sequence 3: Defective dorsal intercalation in die-1 embryos visualized using ajm-1::gfp
In contrast to wild-type embryos, intercalation is defective in homozygous die-1 (w34) embryos. Note that the pharynx detaches from the anterior ectoderm in this mutant as well. The anterior of the embryo is at the upper right.
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Video sequence 4: Defective elongation in die-1 embryos visualized using ajm-1::gfp
In addition to defects in dorsal intercalation, die-1 mutant embryos fail to undergo the next phases of morphogenesis, during which the embryos elongates fourfold prior to hatching into an L1 larva. Although sibling wild-type embryos elongate successfully, mutants do not. The embryo partially visible at the upper right is wildtype; the two embryos that are fully visible are die-1 mutants.
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Video sequence 5: Visualizing protrusive activity in wild-type embryos during dorsal intercalation using lbp-1::gfp
A wild-type embryo carrying the lbp-1::gfp transcriptional reporter was analyzed using multiphoton microscopy. Frames were acquired at 5 min intervals. To suppress cell fusion, the strain was made homozygous for the eff-1 (oj55) allele. Note the basolateral protrusions extended by the dorsal hypodermal cells as they intercalate. The bright ovals are the nuclei of dorsal hypodermal cells, which undergo a contralateral migration as intercalation proceeds. Anterior is to the left.
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Video sequence 6: Cell trasnlocation is defective in die-1 mutant embryos during dorsal intercalation
Protrusive activity in dorsal hypodermal cells in die-1 (w34) embryos was analyzed using lbp-1::gfp. Frames were acquired at 5 min intervals. To suppress cell fusion, the strain was made homozygous for the eff-1 (oj55) allele. Note that although protrusions are extended in w34 embryos, cell translocation does not occur . Anterior is to the left.
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