Meeting Abstract

P3.19  Saturday, Jan. 5  Hox1 expression in normal and regenerating Ptychodera flava hemichordates RYCHEL, Amanda L.*; SWALLA, Billie J.; University of Washington; University of Washington arychel@u.washington.edu

Deuterostomes include the phyla Echinodermata, Hemichordata, Xenoturbellida, and subphyla Tunicata, Cephalochordata, and Vertebrata. Regeneration research in vertebrates has been classically studied in urodele amphibian tails and limbs. Invertebrate deuterostomes may be key models to understanding vertebrate regeneration, as many regenerate far more extensively than vertebrates can. Colonial tunicates can undergo whole body regeneration, and some echinoderms, both larval and adult, when cut in two halves regenerate bi-directionally to form two individuals. We have been studying ptychoderid hemichordates, as they have powerful regenerative abilities. The acorn worm, Ptychodera flava, regenerates the proboscis, collar, stomochord/kidney/heart complex, and collar nerve cord within 30 days of amputation via blastemal epimorphosis. Gill slits eventually form sequentially anterior to posterior in what appears to be a morphallactic process. We have examined Hox1 expression in normal and regenerating Ptychodera flava. In normal adult Ptychodera, Hox1 is expressed weakly in proboscis ectoderm and mesoderm, and more strongly in pharyngeal endoderm. In contrast, Hox1 is strongly expressed in all newly regenerated tissues: ectoderm, mesoderm, and endoderm. These results are the second instance of Hox1 being redeployed during regeneration within the group ambulacraria (echinoderms and hemichordates), since it has also been found to be upregulated in sea star regeneration. Experiments are ongoing to understand the role that Hox gene expression may play in Ptychodera flava regeneration.