Contents
Biotechnology in livestock comprises an arsenal of reproductive biotechniques and molecular genetics. While molecular genetics are poorly developed in swine, reproductive techniques are more advanced and applied under field conditions. This review describes three selected examples of our own research to illustrate the implication of biotechnology in future pig reproduction. Sperm sexing technology is now available and can be used to generate piglets of the desired sex by IVF and ICSI. First studies also indicate satisfactory success rates following intrauterine insemination with sexed spermatozoa. Cloning technique and production of transgenic pigs require information about the regulation and time course of gene expression during in vitro production and preβimplantation development. Information on gene expression is scare in porcine embryos. With the exception of transcripts for the oestrogen receptor gene, no mRNA's from the activated porcine genome have been identified. Recent development of cDNA arrays might help to identify a larger amount of genes in single embryos. Remarkable progress has been made in organ transplantation technology. As the demand for human organs is increasing rapidly, the pig might serve as donor of xenotranplants, provided the transmission of zoonoses from the donor animal to the human recipient is prevented, donor organ anatomy and function are compatible, and immunological rejections (HAR, VAR MAC) can be overcome. The most promising strategy is the synthesis of human complement regulatory proteins in the pig. Transgenic pigs have been generated for hDAF or hCD 46 and their hearts have been transplanted into non human primates for up to 90 days. HCD 59 driven by CMV promotor provides significant protection against HAR at least under in vitro and in vivo conditions. Current studies indicate a temporary use in patients within the next 3β5 years. As the microinjection technology to produce transgenic offspring is time consuming and very expensive, nuclear transfer technology provides a possibility for multiplication without going through the germ line with recombination effects. A functional nuclear transfer system will be crucial for xenotransplantation as it is anticipated that the expression of several transgenes will be required.