Hox and ParaHox Genes in Flatworms: Characterization and Expression1

摘要: Flatworms (phylum Platyhelminthes) are favourite organisms in Developmental Biology and Zoology because of their extraordinary powers regeneration they may hold a pivotal place the origin evolution Bilateria. Hox genes play key roles both processes: setting up new anteroposterior pattern former, as qualitative markers phylogenetic affinities among bilaterian phyla latter. We have searched for ParaHox several flatworm groups spanning from freshwater triclads to marine polyclads and, more recently, acoels, likely earliest extant bilaterian. isolated sequenced eight triclad Girardia tigrina three two polyclad Discocelis tigrina. Data acoels Paratomella rubra Convoluta roscoffensis is also reported. Flatworm sequences 18S rDNA sequence data support clear Platyhelminthes spiralian lophotrochozoans. The basal position acoel flatworms supported recent data, remains still uncertain. Expression intact regenerating adult show nested patterns with graded anterior expression boundaries, or ubiquitous expression. New approaches study function flatworms, such RNA interference briefly discussed.