Abstract

Modern methods in molecular biology have immense practical application in many areas of agriculture and veterinary medicine. These methods include the use of enzymes (restriction endonucleases) that recognise and cleave DNA at specific sites, the cloning of specific fragments of DNA into suitable plasmid or bacteriophage vectors, separation of DNA or RNA fragments followed by fixation to a suitable membrane support, and the use of clones radioactive DNA or RNA probes to detect matching sequences by hybridisation. These methods have been combined to provide powerful new techniques to detect DNA polymorphisms that show Mendelian inheritance. Differences in DNA among individuals can be detected as restriction fragment length polymorphisms (RFLP) or by DNA fingerprinting. Both techniques are used extensively in medicine for the analyses of heritable genetic diseases and genetic mapping. They can also be applied to livestock to find DNA markers linked to important economic traits. We have recently begun screening human DNA probes in a search for RFLPs in New Zealand sheep breeds. The objective of the experiments is to find markers linked with Booroola fecundity (F) gene. Several human DNA probes show specific binding to sheep genomic DNA, demonstrating homology between sheep and humans for some DNA sequences. Techniques which identify linked markers will have immediate application in selection for important major gene traits such as genes affecting fecundity, fleece weight, and disease and parasite resistance. New Zealand is in a strong position to apply linkage studies to important production traits in existing breeding programmes.

SR, Moorhouse, and TM Skerman

Proceedings of the New Zealand Society of Animal Production, Volume 48, , 139-142, 1988