(full paper is archived in the Miller Library)
Title: Expression patterns of bcl-2 in Botryllus schlosseri
Student Author(s): Yazar, Berra
Faculty Advisor(s): Thompson, Stuart
Location: Final Papers Biology 175H
Date: June 2000
Abstract: Botryllus schlosseri is a colonial ascidian that reproduces the entire colony every week through a synchronized asexual budding process. At the end of this seven day cycle, all functional zooids undergo synchronized apoptosis and are resorbed by blastozooids of the new generation. There is evidence that suggests a similar mechanism controls apoptosis in many vertebrates and invertebrates, such as Caenorhabditis elegans and humans. In mammalian cells, experession of certain genes from the bcl-2 gene family regulates apoptosis, the physiological process that eliminates unwanted cells. The purpose of this study was to investigate the role of bcl-2 in apoptosis of B. schlosseri. This study shows that there are at least seven members of the bcl-2 gene family expressed in B. schlosseri. The sequences of two isolated clones of the bcl-2 gene, called bcl-2 B and bcl-2 B+, show a 40% homology with known vertebrate bcl-2 sequences. These genes exhibit differential expression throughout the asexual life cycle. Bcl-2 B maintains a consistent level of expression throughout the asexual life cycle of the colony while bcl-2 B+ is down regulated after the early stages of the zooid lifespan. The results of this study suggest that the bcl-2 gene family might regulate apoptosis in the asexual life cycle of B. schlosseri as well.