Lacking even left-right symmetry, sea anemones are evolutionarily ancient. But during embryogenesis, their larvae compensate for an uninspiring torso by sprouting tentacles from thickened epithelial buds surrounding their mouths. And there’s no time to lose. Freshly hatched sea anemone larvae are under intense pressure to get their tentacles up and running to be able to feed themselves. Associate Investigator Matt Gibson, PhD, and his team wanted to know which kind of cellular reshuffling drives these survival-dependent changes in morphology? The Gibson lab has historically used fruit flies to investigate the control of epithelial cell shape and proliferation during wing, leg and eye development. Breaking with tradition, the lab’s latest study focuses on the starlet sea anemone Nematostella vectensis.
“We thought tentacle outgrowth might be driven by cell proliferation,” says the paper’s first author Ashleigh Fritz, a graduate student at the University of Kansas School of Medicine working in the Gibson lab, who notes that some of Nematostella’s freshwater cousins sprout appendages by constant cell division. “Instead, we observed that cells begin thickened and then thin out as tentacles elongate.” In other words, the process was driven not by cell duplication along a tentacle axis but rather by stretching a stockpile of cells.
In addition to charting how epithelial cell shape changes drive tentacle development, the study is also the first to identify candidate genes driving those changes. Most of all, by putting center stage a new model organism representing one of the simplest animals, it illuminates some of the most fundamental principles animals use to construct a body.
The study was published in the May 1, 2013, issue of Development.