%0 Journal Article
%T Gene expression in bryozoan larvae suggest a fundamental importance of pre-patterned blastemic cells in the bryozoan life-cycle
%A Judith Fuchs
%A Mark Q Martindale
%A Andreas Hejnol
%J EvoDevo
%D 2011
%I BioMed Central
%R 10.1186/2041-9139-2-13
%X We investigated the spatial expression of 13 developmental genes in the larval stage of the gymnolaemate bryozoan Bugula neritina. We found most genes expressed in discrete regions in larval blastemic tissues that form definitive components of the adult body plan. Only two of the 13 genes, BnTropomyosin and BnFoxAB, were exclusively expressed in larval tissues that are discarded during metamorphosis.Our results suggest that the larval blastemas in Bugula are pre-patterned according to their future fate in the adult. The gene expression patterns indicate that some of the bryozoan blastemas can be interpreted to correspond to homologous adult tissues of other animals. This study challenges an earlier proposed view that metazoan larvae share homologous undifferentiated "set-aside cells", and instead points to an independent origin of the bryozoan larval stage with respect to other lophotrochozoans.Bryozoa (Ectoprocta) is a monophyletic group of sessile, colonial invertebrates and includes over 6,000 species in aquatic habitats worldwide [1]. Bryozoan life history, reproduction and anatomy are so fundamentally different from other metazoan groups (for example they lack typical circulatory structures or nephridia and the nervous systems of larvae and adults are unique), that traditional morphological investigations and the fossil record failed to clarify their evolutionary history. Bryozoa belong to Lophotrochozoa [2], but their phylogenetic position within the group is still ambiguous [3-6]. Recently, a few molecular studies indicated a close relationship of bryozoans with the clade Entoprocta + Cycliophora, but with low support [7,8]. Within Bryozoa, three major clades are recognized, Gymnolaemata (Eurystomata), Stenolaemata (Cyclostomata), and Phylactolaemata, but the phylogenetic interrelationships of these groups remain controversial [9-11].Bryozoans have indirect development and their life cycle includes a sexually produced larval stage as well as asexual reproduct
%U http://www.evodevojournal.com/content/2/1/13