| Popis: |
This review describes the manipulation of the sheep genotype by genetic engineering, which is defined as the introduction or elimination of specific genes in the existing cells of an organism through modern biological techniques for the purpose of changing one or more of its phenotypic characteristics. This can be achieved by direct injection of a DNA sequence for a gene or gene-related function or by transfer of an intact nucleus from a somatic cell containing a set of desirable genes into an enucleated egg cell. The potential of transgenesis over conventional breeding is that single gene changes can be made for a particular phenotype without accompanying multiple gene effects that can be disadvantageous. Several examples of engineered sheep are described. The potential for making other transgenic changes are discussed but transgenic sheep research has virtually ceased because of high cost and the perceived low public acceptance of transgenic animals at the present time. |
