Transcript Background About the Pufferfish:

Background About the
Pufferfish:
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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:
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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?
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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?:
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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:
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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:
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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?
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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.
Pufferfish Pictures