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Enucleated Oocyte (enucleated + oocyte)

Distribution by Scientific Domains

Medical Sciences	50%

Selected Abstracts

Engineering tissues, organs and cells

JOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, Issue 2 2007
Anthony Atala
Abstract Patients suffering from diseased and injured organs may be treated with transplanted organs; however, there is a severe shortage of donor organs that is worsening yearly, given the ageing population. In the field of regenerative medicine and tissue engineering, scientists apply the principles of cell transplantation, materials science and bioengineering to construct biological substitutes that will restore and maintain normal function in diseased and injured tissues. Therapeutic cloning, where the nucleus from a donor cell is transferred into an enucleated oocyte in order to extract pluripotent embryonic stem cells, offers a potentially limitless source of cells for tissue engineering applications. The stem cell field is also advancing rapidly, opening new options for therapy, including the use of amniotic and placental fetal stem cells. This review covers recent advances that have occurred in regenerative medicine and describes applications of these technologies using chemical compounds that may offer novel therapies for patients with end-stage organ failure. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Cloning Adult Farm Animals: A Review of the Possibilities and Problems Associated with Somatic Cell Nuclear Transfer

AMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 2 2003
J. L. Edwards
In 1997, Wilmut et al. announced the birth of Dolly, the first ever clone of an adult animal. To date, adult sheep, goats, cattle, mice, pigs, cats and rabbits have been cloned using somatic cell nuclear transfer. The ultimate challenge of cloning procedures is to reprogram the somatic cell nucleus for development of the early embryo. The cell type of choice for reprogramming the somatic nucleus is an enucleated oocyte. Given that somatic cells are easily obtained from adult animals, cultured in the laboratory and then genetically modified, cloning procedures are ideal for introducing specific genetic modifications in farm animals. Genetic modification of farm animals provides a means of studying genes involved in a variety of biological systems and disease processes. Moreover, genetically modified farm animals have created a new form of ,pharming' whereby farm animals serve as bioreactors for production of pharmaceuticals or organ donors. A major limitation of cloning procedures is the extreme inefficiency for producing live offspring. Dolly was the only live offspring produced after 277 attempts. Similar inefficiencies for cloning adult animals of other species have been described by others. Many factors related to cloning procedures and culture environment contribute to the death of clones, both in the embryonic and fetal periods as well as during neonatal life. Extreme inefficiencies of this magnitude, along with the fact that death of the surrogate may occur, continue to raise great concerns with cloning humans. [source]

Dynamics of lamin A/C in porcine embryos produced by nuclear transfer

MOLECULAR REPRODUCTION & DEVELOPMENT, Issue 9 2007
Kiho Lee
Abstract This study was conducted to investigate the presence of lamin A/C in porcine nuclear transfer embryos and to determine whether lamin A/C can serve as a potential marker for nuclear reprogramming. First, lamin A/C was studied in oocytes and embryos produced by fertilization or parthenogenetic oocyte activation. We found that lamin A/C was present in the nuclear lamina of oocytes at the germinal vesicle stage while it was absent in mature oocytes. Lamin A/C was detected throughout preimplantation development in both in vivo-derived and parthenogenetic embryos. Incubation of the activated oocytes in the presence of ,-amanitin (an inhibitor of RNA polymerase II), or cycloheximide (a protein synthesis inhibitor) did not perturb lamin A/C assembly, indicating that the assembly resulted from solubilized lamins dispersed in the cytoplasm. In nuclear transfer embryos, the lamin A/C signal that had previously been identified in fibroblast nuclei disappeared soon after fusion. It became detectable again after the formation of the pronucleus-like structure, and all nuclear transfer embryos displayed lamin A/C staining during early development. Olfactory bulb progenitor cells lacked lamin A/C; however, when such cells were fused with enucleated oocytes, the newly formed nuclear envelopes stained positive for lamin A/C. These findings suggest that recipient oocytes remodel the donor nuclei using type A lamins dispersed in the ooplasm. The results also indicate that lamin A/C is present in the nuclear envelope of pig oocytes and early embryos and unlike in some other species, its presence after nuclear transfer is not an indicator of erroneous reprogramming. Mol. Reprod. Dev. 74: 1221,1227, 2007. © 2007 Wiley-Liss, Inc. [source]

Germinal vesicle materials are not required for the activation of MAP kinase in porcine oocyte maturation

MOLECULAR REPRODUCTION & DEVELOPMENT, Issue 2 2001
K. Sugiura
Abstract The requirement of the germinal vesicle (GV) for the normal kinetics of mitogen-activated protein (MAP) kinase activity during porcine oocyte maturation was investigated. Porcine follicular oocytes were enucleated, and the locations of their extracellular signal-regulated kinases 1 and 2 (ERK1/2), major MAP kinases in maturating porcine oocytes, were detected by indirect immunofluorescent microscopy. The MAP kinase activity was assayed as myelin basic protein (MBP) kinase activity, and the phosphorylation states of ERK1/2 were detected by immunoblotting analyses. Translocation of MAP kinase into the GV and association with the spindle were observed in intact oocytes, while MAP kinase in enucleated oocytes was distributed almost uniformly in cytoplasm throughout the culturing period. The phosphorylation and the activation of MAP kinase were induced, and the activity was comparable with that of control denuded oocytes. The high level of activity was maintained through maturation, even in the absence of spindle formation. These results indicate that the presence of nuclear material and translocation into the GV are dispensable for the activation of MAP kinase and that associating with the spindle is not required for maintenance of its activity though porcine oocyte maturation. Mol. Reprod. Dev. 59:215,220, 2001. © 2001 Wiley-Liss, Inc. [source]