Embryonic chimerism on murine and bovine species: Pattern of interaction between inner cell mass - from embryos produced in vivo - and recipient embryos produced in vitro

Abstract

Embryonic stem cells (ESC) have been used in attempts to obtain specific tissues or even individuals. Due their ability - the pluripotency on generate the three germ layers (ectoderm, mesoderm and endoderm) - a possibility could be the establishment of self-renewal lineages of ESC coming from embryos with an extensive maternal reproductive record (that is, donor cows with superior reproductive performance). Those lineages could be utilized on the generation of chimerical animals as well as animal cloning by nuclear transfer (NT). In this way, obtaining, pluripotency characterization and self-renewal of those lineages could provide interesting opportunities in bovine assisted reproduction technologies. One of these opportunities could be the replacement - partially or totally - of the ICM from recipient embryos by the ESC, with the purpose to obtain gonads and primordial germ cells coming from ESC. To this approach, murine and bovine embryos (produced in vivo and in vitro, respectively) will be utilized as recipients of the ICM originating from embryos obtained in vivo or from parthenogenetically activation, for chimerism induction of the gonads. Donor embryos of ICM will be obtained from transgenic mice (GFP) or Nelore cows (Bos taurus indicus). Will be tested the methodology of ICM reduction (partially and totally) of the recipient embryo in benefit of aggregation and colonization of the ICM from donor embryos. In the extreme case, the recipient embryo would be reduced only to the trophectoderm and all the ICM would come from donor embryo. The ICM transfection with EGFP will be utilized to track - in vitro - the effectiveness of the bovine embryonic chimerism and the fate of the ICM labeled. One of the objectives of this project will be acquire basic knowledge on the establishment of self-renewal ESC lineages, by means of bovine embryos produced in vivo and parthenogenetically coming from superior individuals in Nelore breed. Moreover, will be investigated the effectiveness to obtain chimerical bovine females and the characterization of the chimerical frequency from the ovarian cells. Although this project has a basic research component, it possess in its concept a strong emphasis on the applicability - practical and commercial - due to technique control proposed in this project. Some of these applications could be gene manipulation of the ESC lineages - related to production, reproduction and resistance characteristics - or in the incorporation of transgenes in the lineages. Such modifications in the ESC genotype, associated to NT cloning, could result on inexhaustible sources for bovine bioreactors construction. Finally, the implementation of an animal biotechnology center in the UNESP, campus of Assis, will be a strong basis of supporting and scientific nucleation to the newly created graduation course of biotechnology. (AU)