Summary: RESEARCH ARTICLE
Pilot Morpholino Screen in Xenopus tropicalis
Identifies a Novel Gene Involved in Head
and Nancy Papalopulu3,4*
The diploid frog X. tropicalis has recently been adopted as a model genetic system, but loss-of-function screens in
Xenopus have not yet been performed. We have undertaken a pilot functional knockdown screen in X. tropicalis for
genes involved in nervous system development by injecting antisense morpholino (MO) oligos directed against X.
tropicalis mRNAs. Twenty-six genes with primary expression in the nervous system were selected as targets based
on an expression screen previously conducted in X. laevis. Reproducible phenotypes were observed for six and for
four of these, a second MO gave a similar result. One of these genes encodes a novel protein with previously unknown
function. Knocking down this gene, designated pinhead, results in severe microcephaly, whereas, overexpression
results in macrocephaly. Together with the early embryonic expression in the anterior neural plate, these data indicate
that pinhead is a novel gene involved in controlling head development. Developmental Dynamics 229:289299, 2004.
© 2003 Wiley-Liss, Inc.
Key words: morpholino; Xenopus tropicalis; microcephaly; head development; apoptosis
Received 1 July 2003; Revised 8 September 2003; Accepted 8 September 2003