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09/12/04
The sequencing of the chicken genome
allows a better understanding of the evolution of the vertebrates
 The
Grup de Recerca en Informàtica
Biomèdica (GRIB) - Biomedical Computing Research Group, comprising
researchers at the Institut Municipal d'Investigació Mèdica (IMIM)
- the Municipal Institute for Medical Research, the Universitat
Pompeu Fabra (UPF) and the Centre de Regulació Genòmica (CRG)
- Centre for Genomic Regulation, is the only Spanish group of researchers
that has participated in this scientific project, the results of
which will be made public in the article "Sequence and comparative
analysis of the chicken genome provide unique perspectives on vertebrate
evolution", which appeared in the Journal Nature.
The sequencing, analysis and deciphering
of this genome was in the hands of the Consorci Internacional de
Seqüenciació del Genoma de la Gallina (CISGG) - International Chicken
Genome Sequencing Consortium, made up of almost fifty centres
and laboratories researching throughout the world. Research
was carried out at the Genome Sequencing Centre at Washington University,
in Saint-Louis (USA).
The Spanish group's participation, led
by Roderic Guigó comprising researchers Eduardo Eyras, Robert
Castelo, Josep Francesc Abril, Sergi Castellano, Francisco Cámara
and Genís Parra, contributed in three specific ways to the project:
- It has been able to identify a
set of genes of the chicken genome thanks to the SGP2
programme, a powerful computer tool developed by the GRIB.
- It has carried out a comparative
analysis of human, mouse and chicken genomes.
- It has paid special attention to research
into human genes which are also present in the genomic sequencing
of chickens which were not present in databases available until
then.
It is indeed the first bird genome
ever sequenced, and its strategic position on the evolutionary
tree, between mammals and fish, make it a unique source of information
for the study of the evolution of vertebrates. Birds belong to the
group of arcosauromorphs, which also includes crocodiles and dinosaurs.
Thus, we are dealing with the genomic
sequence analysed which brings us closest to the dinosaurs. The
species of chicken used was the Asian "Red Jungle Fowl" (Gallus
gallus), considered by Charles Darwin (1809-1882) and, later
confirmed by modern genetic studies, the original species of
chicken from which all domestic chickens descend. Their genome,
which consists of 39 pairs of chromosomes, was taken from
a female specimen. The chicken has been an important animal model
in embryology and the study into the development of vertebrates.
The year 1621 saw the first publication of descriptive essays on
the development of the egg and, today, the chicken has also played
an important role in the study of viruses and cancer: The
first oncogenic virus was identified in the chicken. This species'
genomic sequence, together with all the analyses presented in the
Nature article, provided valuable information concerning
the genetics of birds.
In addition to serving as a model animal
for the study of some the 9600 species of birds today, in the context
of interaction with man and the environment, this domestic bird
is of great importance for the agrofood industry, and so
the United States' National Human Genome Research Institute decided
to give priority to the study of its genome in preference
to other farm animals such as the pig or the cow.
On the other hand, the comparative study
of the genomes of different species opens up an interesting new
line of research that may lead us to discovering many aspects that
have not been known about to date concerning human biology
and medicine. In fact, through the comparative study of the
chicken genome with that of mammals sequenced so far (rat, mouse,
man), sequences have been identified which, despite not 'expressing'
any specific protein, are constantly present both in birds and in
mammals. These are the so-called "conserved sequences" and
they represent fragments of genome that have been preserved for
thousands of years and were present prior to the separation of mammals
some 310 million years ago. This type of study allows the
distinction of mammals' ancestral aspects as well as others developed
by them thanks to innovation and adaptation.
Previously, some members of this team
of researchers at the GRIB had already taken part in the final stages
of the analysis of the genomes of the fruit fly, the malaria mosquito
and man, specifically in the visualisation of the maps of
the different gene annotations. They have also been a part of the
international consortia that have carried out genome analysis of
the fungus Dictyostelium, of mice and laboratory rats and the pufferfish,
obtaining the locations of the genes codified in the
sequences of their chromosomes.
For further information:
The
sequencing of the pufferfish genome provides new data on the evolution
of the vertebrates
Scientists
at the UPF, the IMIM and the CRG participate in the sequencing of
the rat genome
Man
and mouse share 99% of genes
Catalan
biologists develop specific software to allow the visualisation
of the complete sequence of the human genome
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