Date of Award
Scott A. Nichols
The body plan of sponges (phylum Porifera) is an outlier among modern animals and is thought to have special evolutionary significance. Sponges lack muscles, nerves and a gut. Instead, they are composed of few cell types and simple tissues that function to pump water through an internal canal network where bacterial prey are filtered by a specialized tissue called the choanoderm. The choanoderm is composed of cells with striking similarity to choanoflagellates, the unicellular relatives of animals. Thus, the traditional view is that the sponge choanoderm is a useful model of the first animal epithelial tissues. Using the freshwater sponge Ephydatia muelleri, we have performed gene expression analysis of the choanoderm tissue and have begun to develop an experimental method to validate and characterize the function of candidate choanoderm genes. The data suggest that the choanoderm may be the only metazoan tissue not reliant on the classical cadherin/catenin complex for cell adhesion. Yet we find evidence for conserved developmental mechanisms and other structural features such as epithelial polarity and microvillar organization. Finally, we will explore the possibility that genes unique to choanoflagellates and sponges, have conserved functions in the choanoderm tissue. This prediction derives from the hypothesized homology of these putatively ancient cell types.
Peña, Jesús Federico, "Gene expression in the choanoderm" (2015). Electronic Theses and Dissertations. 513.
Recieved from ProQuest
Jesús Federico Peña
Cellular biology, Evolution & development, Molecular biology