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It is now more than nine years since Dolly, the world's first somatic cell cloned mammal was born, and the success of somatic cell nuclear transfer (SCNT) is still disappointingly low. Only about 3-5% of reconstructed embryos develop to term, and it is also evident that even if some clones are born, they are not necessarily fully developed and healthy. Embryonic and neonatal abnormalities of cloned offspring are probably a result of incorrect or incomplete reprogramming of the transferred donor cell nuclei. Such an incomplete reprogramming reflects the extremely low efficiency of SCNT. The key role in the process of reprogramming has been attributed to the enucleated oocyte-cytoplast into which the somatic cell nucleus is transferred. In our chapter, we will discuss the methodological approaches used for the preparation of cytoplasts and their possible reprogramming activities.

MeSH
buněčná diferenciace genetika MeSH
buněčné jádro genetika MeSH
cytoplazmatické struktury metabolismus MeSH
embryonální vývoj genetika MeSH
financování organizované MeSH
histony genetika MeSH
klonování organismů metody trendy MeSH
lidé MeSH
oocyty metabolismus MeSH
restrukturace chromatinu genetika MeSH
techniky jaderného přenosu normy trendy MeSH
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Článek

The use of micromanipulation methods as a tool to prevention of transmission of mutated mitochondrial DNA

Current topics in developmental biology. 2007 ; 77 () : 187-211.

ISSN 0070-2153
Medvik
Zdroj

The introduction of different micromanipulation techniques into reproductive and developmental biology has helped us not only to answer many essential biological questions but it is now evident that these techniques also have wide practical applications. In human-assisted reproduction, the most commonly used approach is the injection of a donor sperm into the oocyte cytoplasm--intracytoplasmic sperm injection. It is, however, speculated that with these techniques it would be also possible to improve the oocyte developmental potential especially in those cases when the quality of the cytoplasm is rather poor and thus its function is compromised. Another important application would be the elimination of mutated mitochondrial DNA (mtDNA) by transferring the nuclear material from an abnormal oocyte into a healthy donor oocyte cytoplast. Some of these techniques were already successfully tested in experimental animals, but it is evident that before their introduction into human medicine many questions must be answered, and we must be sure that these approaches are absolutely or almost absolutely safe. In our contribution, we will be specifically oriented to the nuclear (nuclear material) replacement approaches that could be potentially used to prevent the transmission of mutated mtDNA from mother to offspring. Because these techniques are very delicate, some training with oocytes from other species other than human is strongly recommended. 2007, Elsevier Inc.

Článek

No differences in the DNA methylation pattern in mouse zygotes produced in vivo, in vitro, or by intracytoplasmic sperm injection

Fertility and sterility. 2006 ; 86 (5) : 1534-1536.

ISSN 0015-0282
Medvik
Zdroj

The pattern and degree of pronuclear DNA methylation has been evaluated in naturally, in in vitro, or in intracytoplasmic sperm injection (ICSI)-produced mouse embryos. The results show no differences between all experimental groups and confirm the relative safety of IVF and ICSI.