Paxbeta: a novel family of lophotrochozoan Pax genes

• Published in: Evolution & development 2009-11, Vol.11 (6), p.689-696
• Main Authors: Schmerer, Matthew, Savage, Robert M, Shankland, Marty
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Cloning, Molecular; Gene Expression Regulation, Developmental; In Situ Hybridization; Introns; Leeches - genetics; Leeches - physiology; Molecular Sequence Data; Paired Box Transcription Factors - genetics; Phylogeny; Protein Structure, Tertiary; RNA, Messenger - metabolism; Sequence Homology, Amino Acid; Time Factors
• ISSN: 1525-142X
• DOI: 10.1111/j.1525-142X.2009.00376.x

Paxbeta is a novel gene family restricted to the bilaterian superphylum Lophotrochozoa. The Paxbeta paired domain is highly diverged from other bilaterian Pax genes, and we were unable to identify an unambiguous sister-group by phylogenetic sequence analysis. However, conservation of a paired domain intron suggests that the Paxbeta genes arose by duplication and divergence from an ancestral Pax2/5/8 gene. We have identified Paxbeta genes in annelids, molluscs, a nemertean, a brachiopod, and a flatworm, indicating that the founding gene duplication occurred before the separation of those taxa and therefore early in the lophotrochozoan radiation. The leech Helobdella has two genes in this family, Hau-Paxbeta1 and -Paxbeta2, which are expressed during embryonic development. Hau-Paxbeta1 is present in the zygote as a localized maternal transcript, and both show dynamic patterns of apparently zygotic expression during later stages. These later expression patterns differ significantly, but both genes are expressed broadly in the mesoderm and also in the central nervous system during organogenesis.