RESUMO
Somatic Cell Nuclear Transfer (SCNT) technique was used to produce the first viable cloned cattle offspring in Russia. Whole-genome SNP genotyping confirmed that the cloned calf was identical to the fibroblast cell line that was used for SCNT. CRISPR/Cas9 approach was subsequently used to knock out genes for beta-lactoglobulin gene (PAEP) and the beta-lactoglobulin-like protein gene (LOC100848610) in the fibroblast cells. Gene editing (GE) efficiency was 4.4% for each of these genes. We successfully obtained single-cell-derived fibroblast colonies containing PAEP and LOC100848610 knockouts, which will be used to produce beta-lactoglobulin-deficient cattle.
Assuntos
Animais Geneticamente Modificados/genética , Sistemas CRISPR-Cas , Bovinos/genética , Clonagem de Organismos/métodos , Embrião de Mamíferos/citologia , Fibroblastos/citologia , Edição de Genes/métodos , Animais , Animais Geneticamente Modificados/embriologia , Bovinos/embriologia , Embrião de Mamíferos/metabolismo , Fibroblastos/metabolismo , Técnicas de Inativação de Genes/métodos , Técnicas de Transferência NuclearRESUMO
In the absence of activating stimuli, aging processes are initiated in matured mammalian oocytes, which negatively affect the quality of ova and their capacity for further development. On the model of the prolonged culture of bovine oocytes, the dynamics of a number of morphofunctional changes associated with the postovulatory aging was investigated in the present work. In cumulus-enclosed oocytes, migration of the first polar body relative to metaphase II chromosomes started between 18 and 22 h of maturation. The angle of the body deviation from the metaphase plate rose as the culture time increased to 30 h. By 32 h of culture, a gain in the rate of ova with the abnormal chromosome morphology was observed that continued up to 56 h. Furthermore, after 56 h, signs of spontaneous parthenogenetic activation were revealed in 16 percent of matured oocytes. During the prolonged culture of oocytes deprived of cumulus cells after 20 h of maturation, an increase in the frequency of chromosomal abnormalities was found only by 44 h. At the same time the cumulus elimination did not affect the maintenance of the meiosis II blockade in aging ova. Meanwhile, destructive chromosomal changes in oocytes were attended by a gradual rise in the level of apoptotic degeneration and reduction in the proliferative activity of surrounding cumulus cells. The results obtained point to the various temporal dynamics of distinct morphofunctional changes and to the participation of cumulus cells in modulation of the speed of metaphase chromosome destructive modifications in aging bovine ova.