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Characterization of Involution during Sea Urchin Gastrulation Using Two-Photon Excited Photorelease and Confocal
1Department of Molecular Physiology and Biophysics, Vanderbilt University, 702 Light Hall, Nashville, TN 37232-0615
Summary
Sea urchin embryo development involves cell involution during gastrulation, challenging traditional models. New cell-tracking methods reveal continuous epithelial cell movement forming the larval gut.
Area of Science:
- Developmental Biology
- Cell Biology
- Embryology
Background:
- Sea urchin embryos are key models for developmental biology.
- Gastrulation involves primary and secondary invagination stages.
- Previous models assumed limited epithelial cell involution after primary invagination.
Purpose of the Study:
- To investigate epithelial cell involution during sea urchin gastrulation.
- To rigorously assess cell contributions to archenteron and larval GI tract development.
- To challenge the traditional model of sea urchin gastrulation.
Main Methods:
- Developed a novel cell-tracking method using two-photon excited photorelease of caged fluorophores.
- Injected single-cell sea urchin embryos (Lytechinus variegatus) with caged dye.
- Utilized two-photon excitation for noninvasive, 3D-resolved uncaging within living cells.
Main Results:
- Observed continuous cellular involution into the archenteron during both primary and secondary invagination.
- Demonstrated that the larval intestine forms through further cell involution post-secondary invagination.
- Findings contradict the established model of sea urchin gastrulation.
Conclusions:
- Epithelial cell involution is a continuous process throughout sea urchin gastrulation.
- The larval gastrointestinal tract develops via ongoing cell involution.
- The novel cell-tracking techniques are broadly applicable to other embryonic systems.