During development, a single cell divides and differentiates to become a complete multicellular organism. Understanding normal development is essential to understanding both developmental defects and cancers, in which developmental programs have been reactivated resulting in uncontrolled growth and metastasis. Amphioxus (Branchiostoma floridae) is proving an excellent model for development as it is closely related to vertebrates but much simpler both structurally and genomically. The amphioxus genome is fully sequenced and there are extensive libraries of clones of genes expressed in development. Thus, identifying developmental genes and gene networks is proving to be easier in amphioxus than in vertebrate model organisms. Despite these advantages, amphioxus is not widely studied because embryos have only been available during a limited breeding season. The present study builds upon recent breakthroughs in amphioxus husbandry to establish protocols for the continuous culture of amphioxus in the laboratory as well as methods for genetically manipulating amphioxus to determine gene functions. Successful laboratory culture of amphioxus will allow genetic lines of amphioxus to be established, as has been done for such vertebrate models as the mouse and zebrafish, but at lower cost. Thus, the project will open up new avenues for rapidly and economically solving basic developmental processes. All methods and resources developed will be made publically available. The results will be published in peer-reviewed journals and presented at scientific meetings. The work will also provide unique educational opportunities for a graduate student, two undergraduates, and 1-2 high school students per year. Finally, the project will strengthen international collaborations between research laboratories in the U.S. and Taiwan, establish a new web resource for the developmental biology community, and be incorporated into educational outreach activities through the Birch Aquarium in San Diego and the University of Colorado Museum of Natural History. Information about the project will be accessible via www.colorado.edu/eeb/facultysites/medeiros/Home.html.
During development, a single cell divides and differentiates to become a complete multicellular organism. Understanding normal development is essential to understanding how it is disrupted to cause birth defects. Furthermore, because cancers and stem cells share many features with developing cells, understanding basic developmental processes can reveal ways to control these cell types. Much progress has been made in understanding the genetic bases of human development using vertebrate model organisms like mice and zebrafish. However, because of the complexity of the vertebrate genome, it is often difficult to determine the precise roles of particular genes. The chordate amphioxus is an invertebrate, but shares much of its basic structure and biology with vertebrates. Critically, its genome structure and development is similar to that of humans, but much simpler. Because of these features, identifying the genes controlling vertebrate-type developmental processes is potentially easier and faster in amphioxus than in vertebrate model organisms. Despite its advantages, amphioxus is not widely studied because of the difficulty of obtaining amphioxus embryos. The goal of the project was to establish simple, affordable protocols for the continuous culture of amphioxus in the lab to facilitate future developmental and genetic studies. We achieved this goal and have developed detailed methods for raising amphioxus throughout their entire lifecycle. Importantly, these protocols do not require access to a marine facility and can be performed in a small land-locked laboratory using only artificial seawater and low-cost, readily available equipment and reagents. Our methods should work well at colleges and universities regardless of size and funding. The results of this project will open up new opportunities for research into basic developmental biology and genetics, and provide opportunities for students to gain hand-on experience with a key model organism for understanding vertebrate evolution. The performance of this project supported the training of one Ph.D. student, a professional research assistant and provided three undergraduates with hands-on research experience.
