10 Xenomics

Abstract

Xenopus genomics is very much in its infancy. Although large-scale sequencing efforts were slow to be initiated in this system, in the past 3–4 yr there has been an explosion of genomic information accumulating in Xenopus laevis and its diploid relative, Xenopus tropicalis (Fig. 1). Since the beginning of 2003, >320,000 sequences have been deposited in public repositories for X. laevis and >1,100,000 for X. tropicalis, mostly in the form of expressed sequence tags (ESTs). With this expansive amount of new sequence information, X. tropicalis recently jumped into third place on the list of organisms with the most EST’s, behind human and mouse. During the same period of time, the Joint Genome Institute (JGI) has been sequencing the X. tropicalis genome, using a shotgun approach, and it has recently completed 8× coverage. The JGI is currently in the process of assembling the X. tropicalis genome, and it is expected that the JGI will announce its results by the end of 2005.

Now that such an extensive amount of genomic information is becoming available in Xenopus, how will this be useful in our scientific pursuits? This question is best answered by further asking, “What is the ultimate value of obtaining sequence information?” If the ultimate aim is not simply to catalog genes but to understand their function, then it would be very advantageous to find the ideal organisms to study gene function. It is here where the marriage of Xenopus and genomics will reap its full benefits, as Xenopus is...