Date of Award


Document Type

Masters Thesis

Degree Name


Organizational Unit

College of Natual Science and Mathematics

First Advisor

Scott A. Nichols, Ph.D.

Second Advisor

Thomas W. Quinn

Third Advisor

Alysia Mortimer

Fourth Advisor

Bryan J. Cowen


Choanoderm, Sponges, Phylum Porifera, Gene expression analysis


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.

Publication Statement

Copyright is held by the author. User is responsible for all copyright compliance.

Rights Holder

Jesús Federico Peña


Received from ProQuest

File Format




File Size

111 p.


Cellular biology, Evolution & development, Molecular biology