This subproject is one of many research subprojects utilizing theresources provided by a Center grant funded by NIH/NCRR. The subproject andinvestigator (PI) may have received primary funding from another NIH source,and thus could be represented in other CRISP entries. The institution listed isfor the Center, which is not necessarily the institution for the investigator.The digestive tract is an inter-connected organ system essential for the survival of all vertebrates. The digestive tract forms from an embryonic gut tube that undergoes regional patterning and then morphogenesis to define the specialized function of each organ along digestive tract. Of human live births every year, 1:3000 have malformations in the digestive tract that must be immediately treated by surgery. Dr. Theodosiou's research interest primarily focuses on the molecular mechanisms that determine patterning and morphogenesis of the gut tube in the embryo to gain understanding of human abnormalities. Our research in this area takes two approaches: 1) to understand patterning and morphogenesis of the posterior stomach of the chick embryo and 2) to understand the genetic basis for gut tube patterning during vertebrate evolution. Recent work focuses on the origin of the vertebrate colon using the little skate, Leucoraja erinacea, as a model organism. We have established that the presence of high levels of acid mucins in the posterior spiral intestine of L. erinacea provides evidence for a possible primordial water-absorbing organ in the elasmobranchs. In terrestrial vertebrates, Hoxd13 patterns acid mucins found in the colon. Expression of Hoxd13 and Hoxa13 in L. erinacea suggests conserved roles for Hox genes in patterning the early hindgut. Methods to assay for gene function in L. erinacea are being developed to examine the roles of Hoxd13 and a13 during hindgut development.
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