Chicken

Generalities

In addition to its economic interest, the chicken is an excellent model organism, whether in agronomic or fundamental research. For example, it can be used for studies on nutritional quality or embryonic development. This convergence of interests for these two types of research on the one hand, and the development of genomic research and integrative biology on the other, have led to the sequencing of the avian genome, followed by the launch of programmes for the global analysis of this genome.

Until recently, the chicken was little used as a model organism for genetic studies. The sequencing of the genome opens a new era for avian genetics and by extension for vertebrate genetics.

Reproduction

Depending on its species, the hen can lay eggs from the age of 6 to 9 months. The egg is fertilised only if a male is present. In temperate zones, the hen stops laying when the days get shorter (from August to December) and starts again when the days get longer.

During egg laying, the yolk is released into the oviduct where it is surrounded by albumen (the “white” of the egg), and the shell is then produced in the uterus. The hen lays one egg per day or one every two days (100 to 300 eggs per year depending on species and age). Each year, the hen reduces her egg-laying by 20~30% until the oocytes are exhausted. Menopause occurs at around 7 or 9 years of age. Once 8 to 12 eggs are laid in the nest, the hen changes its behaviour and starts to brood.

Embryo development proceeds during an incubation period in which the egg is kept at a temperature of around 38-39°C. This incubation may also be carried out artificially using an artificial incubator. The brood is completed in a perfectly synchronous manner, and chicks communicate before the hatch. Brooding takes 19-21 days, depending on breed and size. The chicks are reared for 1.5 to 3 months depending on the breed.

Tools

Gene regulation or function analysis by transient transgenesis using in ovo electroporation
Transgenesis under development. Possibility to produce chickens expressing the GFP fluorescent reporter gene.
Development of chickens with gene invalidations by ES cell production, with modification approaches by injection of transgenes via electroporations.
large number of natural or selected mutants (for example: the epileptic chicken).

Databases

Genomic databases :

Ensembl : http://www.ensembl.org/Gallus_gallus/Tools/Blast

NCBI : http://www.ncbi.nlm.nih.gov

EST librairy, BBSRC website :

http://www.chick.manchester.ac.uk/

GEISHA website, in situ hybridization:

http://geisha.arizona.edu/geisha/

Infrastructures

Experts

Bibliographyy

http://fr.wikipedia.org/wiki/Gallus_gallus_domesticus