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Genetic Dissection of Growth and Fatness

Using Divergent Intercrosses in Chickens

Jacobsson, Lina (2005). Genetic Dissection of Growth and Fatness. Diss. (sammanfattning/summary) Swedish University of Agricultural Sciences : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2005:52
ISBN 91-576-6951-1
[Doctoral thesis]

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Most phenotypes in human and animals have a multifactorial background, e.g. they depend on many different genes and environmental factors may play a prominent role. Geneticists have long been concerned with identifying key genes responsible for variation in multifactorial traits, such as obesity and diabetes in humans and production traits in animals. In this thesis I have used two different intercrosses to map Quantitative Trait Loci (QTL) for growth and production traits in chicken. The first part of the thesis is based on an intercross between White Leghorn and the ancestor of the modern domesticated chicken, the red junglefowl. A total of 13 QTLs reached genome-wide significance and the four major QTLs explain around 80% of the phenotypic variance between the parental populations in males, indicating that a few QTLs have had a large influence on the enhanced growth rates in domesticated chickens. The second intercross is between two chicken lines divergently selected for body weight at 56 days of age. The selection response has been remarkable and after 42 generations of selection the lines differ almost nine-fold in weight. QTL studies revealed 13 QTLs for growth and each QTL explains a small part of the phenotypic variance within the F2 generation. Altogether, the 13 QTLs explain a smaller part of the population variance compared to the red junglefowl x White Leghorn intercross. For each QTL, the allele from the high line was associated with enhanced growth. Finally, the gene coding for melanocortin receptor 3 (MC3R) was evaluated as a positional candidate gene for an early growth QTL on chromosome 20 in chicken. The analysis showed that the high and low lines are fixed for different MC3R alleles, an observation that strengthens MC3R as a positional candidate gene. Expression analysis revealed a significant differential expression with higher expression in the low line at hatch. Further analyses indicated that this differential expression was primarily due to trans-acting factor(s). The two large QTL studies presented in the thesis has potential to result in identification of causative trait nucleotides for production traits in chickens as well as interesting candidate target genes for human metabolic disorders.

Authors/Creators:Jacobsson, Lina
Title:Genetic Dissection of Growth and Fatness
Subtitle:Using Divergent Intercrosses in Chickens
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :May 2005
Number of Pages:48
ALLJacobsson, L., Park, H.B., Wahlberg, P., Jiang, S., Siegel, P.B. & Andersson, L. 2004. Assignment of fourteen microsatellite markers to the chicken linkage map. Poultry science 83:1825-31. Kerje, S., Carlborg, Ö., Jacobsson, L., Schütz, K., Hartmann, C., Jensen, P. & Andersson, L. 2003. The twofold difference in adult size between the red junglefowl and White Leghorn chickens is largely explained by a limited number of QTLs. Animal genetics 34:264-274. Jacobsson, L., Park, H.B., Wahlberg, P., Fredriksson, R., Pérez-Enciso, M., Siegel, P.B. & Andersson, L. Many QTLs, each with a small effect, explain a large difference in growth between two selection lines in chicken. Manuscript. Park, H.B., Jacobsson, L., Wahlberg, P., Siegel, P.B. & Andersson, L. QTL analysis of body composition and metabolic traits in an intercross between chicken lines divergently selected for growth. Manuscript. Jacobsson, L., Wahlberg, P., Ka, S., Park, H.B., Jiang, S., Denbow, D.M., Siegel, P.B., Hallböök, F. & Andersson, L. Evaluation of MC3R as a positional candidate gene for a growth QTL in chicken. Manuscript.
Place of Publication:Swedish University of Agricultural Sciences
ISBN for printed version:91-576-6951-1
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:?? A01 ??
Subjects:Not in use, please see Agris categories
Agrovoc terms:chickens, genetics, genetic maps, gene location, animal breeding, growth, body weight, egg production
Keywords:chicken, linkage map, Quantitative Trait Loci, growth, egg production, appetite regulation, body composition, metabolic traits, MC3R
Permanent URL:
ID Code:849
Department:(VH) > Dept. of Animal Breeding and Genetics
Deposited By: Lina Jacobsson
Deposited On:16 May 2005 00:00
Metadata Last Modified:02 Dec 2014 10:07

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