title: Subdivisions of the adult zebrafish pallium based on molecular marker analysis.
abstract: BACKGROUND
  The telencephalon shows a remarkable structural diversity among vertebrates. In particular, the everted telencephalon of ray-finned fishes has a markedly different morphology compared to the evaginated telencephalon of all other vertebrates. This difference in development has hampered the comparison between different areas of the pallium of ray-finned fishes and the pallial nuclei of all other vertebrates. Various models of homology between pallial subdivisions in ray-finned fishes and the pallial nuclei in tetrapods have been proposed based on connectional, neurochemical, gene expression and functional data. However, no consensus has been reached so far. In recent years, the analysis of conserved developmental marker genes has assisted the identification of homologies for different parts of the telencephalon among several tetrapod species.
  
  
  RESULTS
  We have investigated the gene expression pattern of conserved marker genes in the adult zebrafish ( Danio rerio) pallium to identify pallial subdivisions and their homology to pallial nuclei in tetrapods. Combinatorial expression analysis of ascl1a, eomesa, emx1, emx2, emx3, and Prox1 identifies four main divisions in the adult zebrafish pallium. Within these subdivisions, we propose that Dm is homologous to the pallial amygdala in tetrapods and that the dorsal subdivision of Dl is homologous to part of the hippocampal formation in mouse. We have complemented this analysis be examining the gene expression of emx1, emx2 and emx3 in the zebrafish larval brain.
  
  
  CONCLUSIONS
  Based on our gene expression data, we propose a new model of subdivisions in the adult zebrafish pallium and their putative homologies to pallial nuclei in tetrapods. Pallial nuclei control sensory, motor, and cognitive functions, like memory, learning and emotion. The identification of pallial subdivisions in the adult zebrafish and their homologies to pallial nuclei in tetrapods will contribute to the use of the zebrafish system as a model for neurobiological research and human neurodegenerative diseases.
authors.affiliation: Biotechnology Center, and DFG-Research Center for Regenerative Therapies Dresden, Technische Universität Dresden, Dresden, 01307, Germany ; Institute of Neuroscience, University of Oregon, Eugene, OR 97403, USA.
authors.forename: Julia
authors.initials: J
authors.lastname: Ganz
authors.affiliation: Biotechnology Center, and DFG-Research Center for Regenerative Therapies Dresden, Technische Universität Dresden, Dresden, 01307, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Kroehne
authors.affiliation: Biotechnology Center, and DFG-Research Center for Regenerative Therapies Dresden, Technische Universität Dresden, Dresden, 01307, Germany.
authors.forename: Dorian
authors.initials: D
authors.lastname: Freudenreich
authors.affiliation: Biotechnology Center, and DFG-Research Center for Regenerative Therapies Dresden, Technische Universität Dresden, Dresden, 01307, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Machate
authors.affiliation: Biotechnology Center, and DFG-Research Center for Regenerative Therapies Dresden, Technische Universität Dresden, Dresden, 01307, Germany.
authors.forename: Michaela
authors.initials: M
authors.lastname: Geffarth
authors.affiliation: Institute of Neuroscience, University of Oregon, Eugene, OR 97403, USA.
authors.forename: Ingo
authors.initials: I
authors.lastname: Braasch
authors.affiliation: Biotechnology Center, and DFG-Research Center for Regenerative Therapies Dresden, Technische Universität Dresden, Dresden, 01307, Germany ; Present address: Faculty of Medicine, Nursing Health Sciences Monash University, Clayton, Victoria, 3800, Australia.
authors.forename: Jan
authors.initials: J
authors.lastname: Kaslin
authors.affiliation: Biotechnology Center, and DFG-Research Center for Regenerative Therapies Dresden, Technische Universität Dresden, Dresden, 01307, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Brand
keywords: Actinopterygii; amygdala; evolution; hippocampus; homology; neuroanatomy; neurogenesis; telencephalon; teleost; vertebrate brain