QUALITY NOT QUANTITY - THE PUFFERFISH GENOME

The genome of the pufferfish, Fugu rubripes (fugu) is compact, With a similar gene complement to mammals and a genome size of just 400 Mb, g ene density is high averaging one every 6-7 kb, Initial characterizati on of this genome has shown that although genes are much smaller and m ore densely spaced, their intron/exon structure is conserved with the resulting introns being small, There is little repetitive DNA in the g enome and this greatly facilitates comparative genomic studies. The co ding content of genes is highly conserved as are critical regulatory e lements of some genes, Other DNA is not, however, and this allows the identification of homologous coding sequence between Fugu and mammalia n genes, Although the genome of Fugu is 7.5 times smaller than the hum an genome, not all genes are reduced proportionately. Some regions of the genome show conserved synteny with mammalian genomes, although at the present time only short physical distances have been examined, The structure of the genome is also being studied, Initial data suggest t hat this may be different to that found in mammals. It is not clear th at the same kind of isochore structure is present in this early verteb rate genome. Patterns of methylation may be different resulting in a d ifferent distribution of CpG islands. An attempt is being made to cent ralize both resources and data from the genome of Fugu so that everyth ing may be integrated into a single, publicly accessible database whic h in turn, may be integrated with databases from other organisms.