Insights on bovine genetic engineering and cloning

Abstract

Pesq. Vet. Bras. 33(Supl.1):113-118, dezembro 2013 113 RESUMO.-[Experiências em clonagem e transgenia em bovinos.] Tecnologias de modificação genética têm se tornado ferramentas essenciais para o desenvolvimento de biotecnologias animais. A clonagem animal mediante transferência nuclear de célula somática (TNCS) possibilitou a geração de animais geneticamente modificados através da utilização de linhagens celulares previamente modificadas e selecionadas como doadoras de núcleo, garantindo desta maneira a geração de rebanhos homogênoes expressando a modificação desejada. O presente estudo objetivou discutir o uso da TNCS como importante metodologia para a produção de rebanhos transgênicos, assim como experiências recentes na manipulação genética de células doadoras de núcleo e possíveis efeitos da indução gênica à pluripotência na TNCS.TERMOS DE INDEXAÇÃO: Pluripotência induzida, tecnologia transgênica, transferência nuclear de célula somática, bovino. INTRODUCTIONThe technology of genetic engineering plays an important role on both basic and applied research, becoming an essential tool for the understanding of the biology and development of animal biotechnology. Such technology presents a wide range of applications, such as the production of biopharmaceuticals, studies on gene expression and its regulation, the improvement of animal production, as, for example, production of herds resistant to specific diseases, and many other biomedical and medical purposes (Jaenisch et al. 1988, Houdebine 2005.Over the last decades several techniques were developed in order to produce genetically modified animals, and three of them became more popular due to their simplicity and positive results: exogenous pronuclear DNA microinjection in zygotes, injection of genetically modified embryonic stem (ES) cells into blastocysts, and, more recently, retrovirus mediated gene transfer (Gordon & Ruddle 1981, Hammer et al. 1985, Gossler et al. 1986, Hofmann et al. 2003, 2004. Injection of ES cells into blastocysts is the most popular methodology of genetic manipulation in mice, once homologous recombination of ES cells in mice is feasible, allowing the contribution of modified cells in the embryos and therefore obtaining transgenic animals after breeding (Misra & Duncan 2002 Transgenic technology has become an essential tool for the development of animal biotechnologies, and animal cloning through somatic cell nuclear transfer (SCNT) enabled the generation of genetically modified animals utilizing previously modified and selected cell lineages as nuclei donors, assuring therefore the generation of homogeneous herds expressing the desired modification. The present study aimed to discuss the use of SCNT as an important methodology for the production of transgenic herds, and also some recent insights on genetic modification of nuclei donors and possible effects of gene induction of pluripotency on SCNT. al . 2007), hindering its use on the production of transgenic herds.As an alternative to the non-feasibility of ES injection in blast...

Improved development of somatic cell cloned bovine embryos by a mammary gland epithelia cellsin vitromodel

“…Some researchers are trying to use immortalized mammary cells lines [ 16 21 ]; however, their effectiveness remains to be evaluated because the immortalized cells used as donor cells display developmental failure of cloned embryos [ 29 ]. In addition, most researchers have to utilize other cells in place of mammary cell lines for production of transgenic animals [ 1 4 33 ]. In fact, these cells are unsuitable for evaluating the function of recombinant protein because expression and secretion of recombinant protein should occur in mammary cells for production of mammary gland bioreactor.…”