Molekulare Analysen zur Fussentwicklung von Hydra
The foot of Hydra is a dynamic structure, a place of permanent cell displacement, determination and differentiation. (1) Characterization of PPOD (putative peroxidase) genes in different Hydra species. The PPOD gene family shows an increase in complexity on the genomic level in the course of Hydra phylogeny, thus revealing interesting aspects of Hydra genome evolution. The differential regulation of PPOD genes is demonstrated and recommends different members of this effector gene family as valuable tools to study the differential gene expression in the context of foot formation in Hydra. (2) The homeobox transcription factor CnNK-2 plays a crucial role in foot formation processes in Hydra. Here we analyzed the CnNK-2 promoter region by means of phylogenetic footprinting. By electrophoretic mobility shift assays (EMSA) we show that an interspecific conserved HNF-3beta binding motif in the promoter region of CnNK-2 is specifically bound by budhead, a Hydra HNF-3beta-homologue associated with the Hydra head organizer. The interaction of budhead with the CnNK-2 cis regulatory region is the first hint for the molecular basis of the well known cross talk between head, bud and foot patterning systems in Hydra.