title: Search for the evolutionary origin of a brain: planarian brain characterized by microarray.
abstract: The origin of the brain remains a challenging problem in evolutionary studies. To understand when and how the structural brain emerged, we analyzed the central nervous system (CNS) of a lower invertebrate, planarian. We conducted a large-scale screening of the head part-specific genes in the planarian by constructing a cDNA microarray. Competitive hybridization of cDNAs between a head portion and the other body portion of planarians revealed 205 genes with head part-specific spikes, including essential genes in the vertebrate nervous system. The expression patterns of the top 30 genes showing the strongest spikes implied that the planarian brain has undergone functional regionalization. We demonstrate the complex cytoarchitecture of the planarian brain, despite its simple superficiality of the morphology.
authors.affiliation: Center for Information Biology and DNA Data Bank of Japan, National Institute of Genetics, Mishima, Japan.
authors.forename: Masumi
authors.initials: M
authors.lastname: Nakazawa
authors.forename: Francesc
authors.initials: F
authors.lastname: Cebrià
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Mineta
authors.forename: Kazuho
authors.initials: K
authors.lastname: Ikeo
authors.forename: Kiyokazu
authors.initials: K
authors.lastname: Agata
authors.forename: Takashi
authors.initials: T
authors.lastname: Gojobori
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000033:anatomy & histology* / Q000166:cytology; D020869:Gene Expression Profiling; D017403:In Situ Hybridization; D007564:Japan; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D010932:Planarians / Q000033:anatomy & histology* / Q000235:genetics*; D016415:Sequence Alignment