Animal Transgenesis and Applications

Cloning is asexual reproduction from of some selected individuals in such a way that the newly produced offspring is like their parent in genetic content. The base of cloning is transferring nucleus (somatic or stem cell) into enucleated oocyte. Considering the purpose, there are two types of cloning: reproductive cloning with purpose of having an offspring that is similar to his parent in genetic content and therapeutic cloning whose main purpose is to useembryo stem cells for curing some diseases especially degenerative ones. This is a multistep process and its steps include: donor cell, the recipient oocyte, nuclear transfer process, embryo culture, and embryo transfer. Cloning can be applied in different areas including genetic engineering, protecting a special species, domestic animal cloning, and therapeutic cells through embryo stem cell nuclear transfer. One of the main purposes of cloning is producing transgenic animals. Transgenesis is the process of transferring the sequence of forign DNA to multicellular organism and making sure that theses sequences will be transferred to the offsprings. Genetic engineering technology has provided a more efficient way for gene transfer in cows, pigs, sheep, goats, chickens, and fish. Transgenic animal reproduction has many different advantages. Some of them include: producing more efficient animals for the purpose of studying about human related diseases, producing animals for the purpose of using medical protein, using their organs for transplantation, producing animals for the purpose of regulating gene expression and the coding sequence. Right applications of gene transfer in farm animals improve the quality and quantity of yield, disease resistance, production of valuable proteins in the milk glands or other organs, genetic modifications of pigs for xenotransplantation and production of new animal models for the time when the rodent cannot be applied for the problem of interest. This paper reviews the recent advances and applications of transgenesis in livestock and their derivative products. We also analyze here some emerging applications of livestock transgenesis in the field of pharmacology, meat and dairy industry, xenotransplantation, and human disease modeling.