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Abstract: Fanconi anemia (FA) is a complex disease involving nine identified and two unidentified loci that define a network essential for maintaining genomic stability. To test the hypothesis that the FA network is conserved in vertebrate genomes, we cloned and sequenced zebrafish (Danio rerio) cDNAs and/or genomic BAC clones orthologous to all nine cloned FA genes (FANCA, FANCB, FANCC, FANCD1, FANCD2, FANCE, FANCF, FANCG, and FANCL), and identified orthologs in the genome database for the pufferfish Tetraodon nigroviridis. Genomic organization of exons and introns was nearly identical between zebrafish and human for all genes examined. Hydrophobicity plots revealed conservation of FA protein structure. Evolutionarily conserved regions identified functionally important domains, since many amino acid residues mutated in human disease alleles or shown to be critical in targeted mutagenesis studies are identical in zebrafish and human. Comparative genomic analysis demonstrated conserved syntenies for all FA genes. We conclude that the FA gene network has remained intact since the last common ancestor of zebrafish and human lineages. The application of powerful genetic, cellular, and embryological methodologies make zebrafish a useful model for discovering FA gene functions, identifying new genes in the network, and identifying therapeutic compounds. [Copyright &y& Elsevier]

Abstract: Extensive search for the orthologs of 10 human voltage-gated calcium channel (VGCC) α1-subunit genes in the Fugu genome sequence revealed 21 α1-subunit genes in the compact genome of Fugu. Subtype classification of the identified Fugu α1 orthologs based on phylogenetic analysis, genomic organization and sequence comparison of the most divergent II/III loop and the C-terminal regions of the α1-subunits indicated extra copies of α1S-, α1D-, α1F-, α1A-, α1E-, α1H- and α1G-subunit genes. Phylogenetic analysis reveals that this is likely due to fish lineage specific α1-subunit subtype duplication. Sequence comparison shows that many of the structural features characteristic of VGCC and specific channel subtypes are also present in the Fugu α1-subunits. All the Fugu α1-subunits showed similar expression profile to that of the mammalian α1-subunits except for Fugu α1S, α1A, α1B and α1H which have a more widespread tissue distribution. These results indicate that Fugu, a lower vertebrate, has more extensive channel heterogeneity compared to human. [Copyright &y& Elsevier]

Three orthologous genes encoding programmed cell death 2 (PDCD2), TATA-binding protein (TBP), and proteasomal subunit C5 (PSMB1) proteins have been shown previously to be nonrandomly distributed in both mammalian and invertebrate genomes. Here we analyze a conserved synteny of the PDCD2, TBP, and PSMB1 orthologs in four nonmammalian vertebrates. Homologous genes of the chicken, zebrafish, fugu, and Tetraodon nigroviridis were identified. A chicken cosmid harboring the orthologs of these three genes was completely sequenced. The fish genes were analyzed in silico. In all seven vertebrates thus far investigated, the PDCD2 and TBP genes are located tail-to-tail. In six tested species but the zebrafish, the PSMB1 gene mapped head-to-head or in the close vicinity to the TBP, but even in the zebrafish, all three genes were syntenic. In contrast, a three times reused synteny breakpoint in the 5′-region from PDCD2 was detected. A comparative analysis revealed the distribution of putative matrix-attached regions (MARs), which may affect the synteny conservation. [Copyright &y& Elsevier]