The main objectives are as follows:
* To map quantitative trait loci which are segregating in pedigrees which have been specially constructed by crossing susceptible zebu with trypanotolerant N'Dama.
* Typing of associated markers in populations which consist of purebred African trypanotolerant cattle
* Typing of associated markers in populations which are crossbred in origin but which have been under strong trypanosomiasis challenge.
* A search for DNA sequence polymorphisms in markers and functional genes in candidate regions will be conducted and these will be similarly typed and analysed in hybrid populations
* Verified markers will be typed in a series of Togolese cattle populations which have been characterised for a series of trypanotolerance-defining parameters. The power of trypanotolerant markers in predictive epidemiology will be assessed.
Trypanosomiasis is a major constraint to livestock production in Africa. However, some of the indigenous Bos taurus populations of cattle are markedly resistant to the effects of the disease. The trait responsible, termed trypanotolerance, is heritable and quantitative in nature but its genetic basis is unknown. The identification of chromosomal regions which contain major genes determining trypanotolerance would be a valuable contribution to African agriculture: - aiding selection programmes, conservation measures and adding to the basic scientific understanding of disease resistance, possibly leading to the development of entirely novel disease control approaches. This project will identify such regions, verify them using independent analyses, and refine the map position of the trait loci. An assessment of their importance in the field will also be conducted. Close collaboration between DCs and European institutes, together with personnel exchanges will lead to training and technology transfer, and a strengthening of the scientific base in the DCs.
The key activities envisaged are:
* Sampling and DNA extraction of animals from a range of population in each of Senegal and Togo, choosing locations of high trypanosomiasis challenge.
* Preliminary population typing of these samples with diagnostic microsatellites and selection of four hybrid and two pure taurine populations
* Further sampling of dam/offspring pairs from these. Establishing of DNA sample banks
* Typing of pedigree DNA samples with a genome-wide panel of markers.
* Identification of chromosome regions containing trypanotolerance loci.
* Identification of further markers and/or sequence polymorphisms which reside in these regions, typing of these in both hybrid and pure taurine, trypanotolerant populations. Also typing of the same markers in reference populations for comparison. Deduction of composite haplotype frequencies and levels of admixture at candidate regions in the test populations.
* Analysis of evidence of reduced introgression of zebu introgression at candidate region loci in hybrid populations. Analysis of variance of microsatellite length in pure taurine populations.
* Epidemiological analyses
* Personnel exchange between project partners. Publication of data and results in both traditional and electronic format.
Funding SchemeCSC - Cost-sharing contracts
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