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Background About the Pufferfish: . Fugu is a teleost fish belonging to the order Tetraodontiformes. Fugu rubripes, an eukaryota and vertebrate, more commonly known as the Japanese pufferfish. There are nearly 100 kinds of pufferfish worldwide. They can grow up to 70.0 cm.
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Background About the Pufferfish: • Fugu is a teleost fish belonging to the order Tetraodontiformes. • Fugu rubripes, an eukaryota and vertebrate, more commonly known as the Japanese pufferfish. • There are nearly 100 kinds of pufferfish worldwide. • They can grow up to 70.0 cm. • The Fugu genome is the first vertebrate genome to be draft sequenced after human.
Human vs. Torafugu: • Fugu are our very distant cousins. • Fish have nearly all of the same organ systems and physiology as humans, in contrast to flies and worms. • Three quarters of the pufferfish's 31,000 genes have direct human counterparts. • Among the 25% of human genes without counterparts in Fugu are key genes involved in the human immune system and metabolic regulation. • Conserved linkages found between Fugu and human genes indicate the preservation of chromosomal segments from the common vertebrate ancestor, but with some shuffling of gene order, segmental duplications, chromosomal rearrangements and 'loss' and 'gain' of introns. • Nearly 1,000 genes in the pufferfish Fugu rubripes are apparently identical to previously unidentified ones in humans.
How Big is the Fugu Genome? • Pufferfish have the smallest known vertebrate genomes, only 390 million bases long, which is about eight times small than the 3000 Mb human genome, yet contains many genes similar to humans. • Fugu has 22 pairs of chromosomes. The pufferfish genome is so condensed that the genes are contained in about 15 percent, compared to the human genome with only 3 percent, repetitive DNA accounts for less than one-sixth of the sequence. • Intergenic regions and introns in the Fugu are highly compressed and the average gene density is about one gene per 10 kb. • It has been found that the number of genes in the pufferfish is approximately the same as in man.
When was the genome of the fugu rubripes completely sequenced?: • On October 26, 2001, the completion of the Fugu sequencing project was announced at the 13th International Genome Sequencing and Analysis Conference (GSAC) in San Diego, California.
Why the Pufferfish was Chosen to be Sequenced: • Fugu was proposed as a model vertebrate genome to understand the more complex human genome and other vertebrate genomes. It is expected that comparisons of the human genome with that of Fugu will help us understand the information encoded in the human genome. This, in turn, paves the way for finding new drugs to cure diseases.
Advantages of Studying the Genome of the Pufferfish: • One advantage is that puffer fish’s genome is condensed and contains less repetitive sequences is that it helps save time and is cost effective, making it easier to get from one end of a pufferfish gene to the other end and from one gene to the next when determining DNA sequence on continuous stretches of chromosomes.
Another advantage… to studying the pufferfish is that, compared to other important model organisms, including fruitflies, the pufferfish is closer to humans on the evolutionary scale, and will have more of the same genes.
What Have We Gained? • As many as a quarter of all human proteins could not be recognized in the pufferfish sequence when the two genomes were compared directly. It has been speculated that the human complexity must have arisen from differences in gene splicing or gene expression. • It has been discovered that their exist presence of a relative handful of "giant" genes - genes, which appear bigger than their human counterparts, it has also been found that there are other areas of conserved synteny between pufferfish and human genomes.
Comparisons between the pufferfish and human genome show the evolution of the protein sequences, and to predict the existence of human genes, and elements that control or regulate the activity of genes. Comparing with the pufferfish genes, about 1000 human genes have been found which had not been found in other databases.
How Was the Fugu Genome Mapped? • Researchers first chopped the DNA into fragments four million pieces, small enough to be sequenced. DNA fragments were sequenced at random and the order then assembled in a computer, the so called "whole genome shotgun"(WGS) method.
Who Started the Fugu Genome Project?: The Fugu genome project was initiated in Cambridge, Britain, in 1989 by Sydney Brenner and his colleagues Greg Elgar, Sam Aparicio and Byrappa Venkatesh. The Institute of Molecular and Cell Biology (IMCB) took up the research soon afterwards. The genome was sequenced by the International Fugu Genome Consortium.
