INTERCALATION

Cpaa_ablationC. elegans embryo expressing AJM-1::GFP in which the founder cell Cpaa was ablated to remove the left-hand dorsal epidermal cells [Ryan King].

Dorsal epidermal cells comprise two rows of epithelial cells that lie along the dorsal midline and extend along much of the anterior-posterior axis. These cells intercalate to form a single row of cells. Since there are only 20 cells that intercalate, it is perhaps the simplest known system for studying directed cell rearrangement during embryonic development. Click on the links to see examples videos…

Dorsal intercalation in a wild-type embryo visualized using Nomarski microscopy. Anterior to the left, dorsal view. (30 sec/frame). E. Williams-Masson (Williams-Masson et al., 1998; PubMed).
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Dorsal intercalation in a wild-type embryo visualized using a dlg-1::gfp translational fusion (Koeppen et al., 2001; PubMed). Frames were acquired at 5 min intervals.
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We are taking several approaches to study dorsal intercalation that include:
(1) Determining how a Rac/RhoG-dependent actomyosin network regulates intercalation;
(2) Determining how cells insert protrusions between neighbors during intercalation;
(3) Determining what pathways orient cells during dorsal intercalation.