Plant & Animal Genome IX Conference Plant & Animal Genome IX Conference
Poster: Sequencing & EST
P01_22.html
Together with a large-scale analysis of the pufferfish Tetraodon nigroviridis genome by a genome scanning survey approach, we have started a specific sequencing project concerning regions of this compact genome encoding genes of the immune response to gain more information on this system, which is present in all vertebrates from the Gnatosthomes, but only partially documented in teleost fish. Genes of the immune response are organized at the genomic level in clusters of linked gene segments covering in some cases very large regions. However, most of the studies conducted in teleost fish are dealing with the identification, structure organization and diversity of the expressed products. Moreover, all chains encoding the Tetrapods homologous polypeptides have not been yet identified in teleost fish, whereas novel-type antigens receptors have been described in the latter. We have undertaken the complete sequencing of immune regions (T-cell receptor alpha, immunoglobulin light chain, immunoglobulin heavy chain, immunoglobulin novel-type and Major Histocompatibility Class I) and flanking sequences in Tetraodon nigroviridis. Based on the presence of these genes on the single-path sequences obtained from the Tetraodon nigroviridis genome survey, BAC clones have been chosen for sequencing and contigs of two or more overlapping clones have been constructed to encompass the whole loci. Additional data were given by use of fluorescence in situ hybridization on metaphasic chromosomes of probes derived from these regions. Sequencing, RT-PCR analysis and cDNA screening provided evidences for the fonctionality, the structural rearrangement and the generation of diversity mechanisms of the loci investigated. Analysis of these data shows both general and fish-specific features in the genomic organization of immune regions.