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Utilizing DNA testing in identifying multiple gene traits

Utilizing DNA testing in identifying multiple gene traits. Prof Norman Maiwashe 1,2 (PhD, Pri Sci Nat) 1 ARC-Animal Production Institute 2 Dept. of Animal, Wildlife and Grassland Sciences

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Utilizing DNA testing in identifying multiple gene traits

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  1. Utilizing DNA testing in identifying multiple gene traits Prof Norman Maiwashe1,2 (PhD, Pri Sci Nat) 1ARC-Animal Production Institute 2 Dept. of Animal, Wildlife and Grassland Sciences Animal Breeding and Genetics University of the Free State Private Bag X2, Irene, 0062 Bloemfontein, 9300 Stud Game Industry Workshop – 15 March 2013 – Bela-Bela

  2. Off with a disclaimer • I am a livestock geneticist and therefore do not claim any expertise about game • BUT, I think we can compare notes • Genetics is genetics anyway

  3. The purpose of presentation • To highlight the importance of phenotypic and DNA data as raw materials for application of biotechnology in genetic improvement programmes

  4. PresentationOutline • Genetics of complex traits • Genetics versus environment • Horn length: A Soay Sheep example • Using DNA in selection for complex traits • Concluding Remarks

  5. What are complex traits? • These are traits or characteristics influenced by: • multiple genes and • often by the environment P = G + E • Distinguishing genetic from environmental effects is therefore difficult • Improvement of these traits through selection is a challenge • A good phenotype does not necessarily mean good genetics and vice versa

  6. Genetics versus Environment • Heritability provides an indication of the proportion of the total variation that is due to genetics • Example Trait: horn length • Has a heritability of 33% in Soay Sheep • Thus, environment account for 67% of the variation in horn length • It can be concluded that horn length is under genetic control • Question? • How many genes are involved?

  7. Using DNA to find genes or markers • Genetic markers • Part of DNA that does not affect the trait • Widespread in the genome • Easy to stumble on a genetic marker than a gene • Large numbers of genetic markers (SNPs) have been discovered recently • Since some of these markers are in close proximity to genes, markers can be used as proxies (indicators) for genes • We have been quite successful in finding genetic markers but not the genes themselves

  8. Genetic markers for horn length • Soay sheep: • Genetic marker or region in DNA associated with horn length found in Chromosome 1 (Johnston et al., 2010) • Differences in this piece of DNA explains almost all the genetic variation (additive ) in horn length • What does this mean? • Genetic markers can be used to select for horn length

  9. Finding genetic markers and using them • What is required? • Discovery population of animals • Phenotypic data (measurements) • Genotypic data on genetic markers (DNA) • Validation population • The associations between phenotypes and genotypes should be validated in independent populations (validation) • Once the genetic markers are identified and validated genetic tests are commercialised

  10. How does it work in practice? • Collected biological sample • Hair, blood, etc. • Send the sample to the laboratory • DNA extraction and sample analyses • Report on the genetic status sent back to farm • Information used for selection

  11. What should the game industry do to benefit from DNA technology? • Set-up a programme for: • Data collection on traits of economic importance • Collection of biological samples • Invest in R & D • In genetics underlying expression of phenotypes • In biotechnology

  12. Summary • Our knowledge of genetics underlying important traits in game species is at its infancy • The game industry is well-positioned to provide leadership in R & D in game species • Investment in R & D would ensure long-term sustainability of the game industry • The ARC is committed to positively contribute to R & D efforts for the benefit of the game industry

  13. Thanks For You Attention

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