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Title: The biochemical and molecular genetics of ornithine decarboxylase in chickens
Author: Johnson, Ruth
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1990
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The role of ornithine decarboxylase (ODC) was investigated in muscle and embryos of different chicken lines selected and unselected for increased growth and weight-for-age. Both lines showed a peak in muscle ODC activity at 5-6 days post hatch which can be up to 4-fold higher in the selected line. Use of α-difluoromethylornithine (DFMO) to try to inhibit this activity in the selected line produced birds which had significantly lower body weight, but not muscle weight or muscle ODC activity, than control birds. It seems that treatment may have been started too late (4 days post-hatch) to have a significant effect on muscle ODC activity, but still affected overall growth rate. ODC activity in embryos showed a peak at 4-5 days. This was found to be highest in embryos from strains which showed fastest growth rates at this particular stage, but this did not necessarily reflect the pattern found in post-hatch growth. In all strains examined at this stage the ODC activity was found to be higher in the head region than in the rest of the embryo. A cDNA clone was isolated from a chicken embryo cDNA library using a mouse ODC probe. The DNA sequence of this clone was found to be 78% homologous to the human ODC sequence and almost 90% homologous at the amino acid level. This amount of sequence conservation suggests an extremely important role for this enzyme. This cDNA hybridized to several bands in chicken genomic DNA in a way which suggests that there is only a single ODC gene in chickens. It also detected a Haelll polymorphism between broiler and layer strains which is at the 3' end of the gene. Probing Northern blots with this probe indicated the presence of two transcripts, which closely correspond both to the size predicted from the cDNA clone and to the size of mRNAs found in other species. It is suggested that many pathways of investigation are opened up by the work presented here. Further investigation might involve use of the chicken ODC cDNA to investigate the cause of the differences in ODC activity between strains, cloning of the chicken ODC gene, and the use of transgenics to study the role of ODC in growth and development. Myoblasts and satellite cells in culture will also provide a useful system for studying ODC activity and expression and its involvement in muscle growth.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available