Somatic cell nuclear transfer in non-enucleated goldfish oocytes: understanding DNA fate during oocyte activation and first cellular division
Résumé
Nuclear transfer consists in injecting a somatic nucleus carrying valuable genetic information into a recipient oocyte to sire a diploid ofspring which bears the genome of interest. It requires that the oocyte (maternal) DNA is removed. In fsh, because enucleation is difcult to achieve, non-enucleated oocytes are often used and disappearance of the maternal DNA was reported in some clones. The present work explores which cellular events explain spontaneous erasure of maternal DNA, as mastering this phenomenon would circumvent the painstaking procedure of fsh oocyte enucleation. The fate of the somatic and maternal DNA during oocyte activation and frst cell cycle was studied using DNA labeling and immunofuorescence in goldfsh clones. Maternal DNA was always found as an intact metaphase within the oocyte, and polar body extrusion was minimally afected after oocyte activation. During the frst cell cycle, only 40% of the clones displayed symmetric cleavage, and these symmetric clones contributed to 80% of those surviving at hatching. Maternal DNA was often fragmented and located under the cleavage furrow. The somatic DNA was organized either into a normal mitotic spindle or abnormal multinuclear spindle. Scenarios matching the DNA behavior and the embryo fate are proposed.
Origine : Accord explicite pour ce dépôt
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