249 Bulletin UASVM, Veterinary Medicine 67(1)/2010 ISSN 1843-5270; Electronic ISSN 1843-5378 Animal Transgenesis and its Applications PUSTA Dana * , Rodica SOBOLU *** , Ioan PAŞCA * , Mariela MILITARU ** * University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca, *Faculty of Veterinary Medicine, *** Faculty of Horticulture Str. Mănăştur nr. 3-5, 400372 Cluj-Napoca, Romania, e-mail: danapusta@yahoo.co.uk ** University of Medicine and Pharmacy “Iuliu Ha ieganu” Cluj-Napoca Abstract. Nowadays, breakthroughs in molecular biology are happening at an unprecedented rate. One of them is the ability to engineer transgenic animals, i.e., animals that carry genes from other species. The technology has already produced transgenic animals such as mice, rats, rabbits, pigs, sheep, cows or microorganisms. This article presents the basics of the transgenesis technology and its applications in medicine, agriculture and industry. Key words: animal transgenesis, applications in medicine, agriculture and industry. INTRODUCTION There are several definitions for the term transgenic animal. The term transgenic animal refers to an animal in which there has been a deliberate modification of the genome - the material responsible for inherited characteristics - in contrast to spontaneous mutation (Federation of European Laboratory Animal Associations September 1992, revised February 1995). Foreign DNA is introduced into the animal, using recombinant DNA technology, and then must be transmitted through the germ line so that every cell, including germ cells, of the resulted animal contains the same modified genetic material. The transgenesis determines different genome modifications, whether by the insertion of a new gene, whether by the temporary or definitive inactivation of a gene already existent into the genome. The insertion of a foreign gene (transgene) into an animal is successful only if the gene is inherited by offspring so this is the reason why the success rate for transgenesis is very low. METHODS OF CREATION OF THE TRANSGENIC ANIMALS For practical reasons, i.e., their small size and low cost of housing then for larger vertebrates, their short generation time, and their fairly well defined genetics, mice have become the main species used in the field of transgenesis. The three principal methods used for the creation of transgenic animals are DNA microinjection, embryonic stem cell-mediated gene transfer and retrovirus-mediated gene transfer. a) DNA microinjection This method involves the direct microinjection of a chosen gene construct (a single gene or a combination of genes) from another member of the same species or from a different species, into the pronucleus of a fertilized ovum. The foreign DNA (gene) must be integrated into the genome prior to the doubling of the genetic material that precedes the first cleavage in order for the animal to be born with a copy of this new information in every cell. For several hours following the entry of the sperm into the oocyte, the male and the female pronuclei can brought to you by CORE View metadata, citation and similar papers at core.ac.uk