Molecular Biology of Organismal Diversity

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Relationship between molecular evolution and organismal evolution, an important problem left to be clarified in molecular evolution field, have been studied in collaboration with researchers from three research fields, molecular evolution, molecular developmental biology, and molecular physiology. Our results of this project are as follows. (1)Takashi MIYATA (Kyoto Univ.), "The molecular bases of organismal diversity" : A molecular phylogeny-based analysis of several animal-specific gene families revealed that gene diversification had been completed before the parazoan-eumetazoan split and therefore there is no direct link between gene diversification and the Cambrian explosion. (2)Yoshinori SHICHIDA (Kyoto Univ.), "Functional diversity of visual pigments and its relationship with diversity of vision" : Functional analyses of the mouse models constructed using knock-in technology revealed close relationship between diversification of a visual pigment and that of a visual function. (3)T … More akashi GOJOBORI (National Inst. Genetics), "Study for biodiversity by comparative genomics and the database for expressed cDNA on planarian brain" : The pattern of commonly expressed genes in ear and eye suggested the common ancestral organs of ear and eye existed before diversification of those two organs. (4)Hiroshi HORI (Nagoya Univ.), "Active medaka transposon and genome rearrangement" : We succeeded in isolating the medaka fish transposable element, Tol2, and characterized the regulatory mechanism in the medaka genome, involving the expression of these mRNAs. (5)Shigeru KURATANI (RIKEN CDB), "Molecular developmental studies on vertebrate jaw evolution" : We isolated lamprey cognates of regulatory genes known to be involved in jaw patterning in gnathostomes and showed that oral patterning in the lamprey is based on the shifted cell-cell interactions between the epithelium and crest-derived ectomesenchyme as compared to that in gnathostomes. (6)Kiyokazu AGATA (RIKEN CDB), "Unraveling a fundamental genetic program for brain development and investigating the change of it in the brain evolution process" : Using EST, DNA microarray, in situ hybridization, and RNAi technologies, we succeeded in isolating a novel gene, noudarake, which involved in planarian brain formation. (7)Masami HASEGAWA (Inst. Statistical Math.), "Development of methods for molecular phylogenetics and their application to mammalian evolution" : Various methods for inferring molecular phylogenies based on the maximum likelihood method were developed. Applying these methods to mammalian and protistan evolution, we found frequent convergent evolution in morphological level. (8)Yoichi MATSUDA (Hokkaido Univ.), "Evolution of birds and reptiles inferred from genome structure" : Comparative cytogenetic maps of the Chinese soft-shelled turtle and the Japanese four-striped rat snake were constructed with EST clones. The cytogenetic maps revealed the close relatedness of turtles to birds rather than to snakes. We also showed that the avian and snake sex Z chromosomes were derived from the different chromosomes of the common ancestor. (9)Norihiro OKADA (Tokyo Inst. Tech.), "Diversification and speciation mechanism of cichlid fishes of Lake Victoria in Africa" : We found population-specific variation at the long wavelength-sensitive (LWS) opsin locus from more than 200 endemic species of haplochromine fishes in the East African Lake Victoria which would provide an insight into species formation. Less