Calcisponges have a ParaHox gene and dynamic expression of dispersed NK homeobox genes

摘要: Sponges are simple animals with few cell types, but their genomes paradoxically contain a wide variety of developmental transcription factors, including homeobox genes belonging to the Antennapedia (ANTP) class, which in bilaterians encompass Hox, ParaHox and NK genes. In genome demosponge Amphimedon queenslandica, no Hox or present, linked tight cluster similar clusters bilaterians. It has been proposed that originated from after divergence sponges lineage leading cnidarians On other hand, synteny analysis lends support notion absence is result secondary loss (the ghost locus hypothesis). Here we analysed complete suites ANTP-class homeoboxes two calcareous sponges, Sycon ciliatum Leucosolenia complicata. Our phylogenetic analyses demonstrate these calcisponges possess orthologues bilaterian (Hex, Hmx Msx), varying number additional one gene, Cdx. Despite generation scaffolds spanning multiple genes, find evidence clustering All developmentally expressed, patterns suggesting involvement type specification embryos adults, metamorphosis body plan patterning. These results predate origin thus confirming hypothesis, highlight need analyse sponge lineages obtain picture ancestral composition first animal genome.