• MeSH
• buněčné dělení MeSH
• buněčné jadérko fyziologie   ultrastruktura   MeSH
• finanční podpora výzkumu jako téma MeSH
• kultivované buňky MeSH
• metafáze MeSH
• mikrochirurgie MeSH
• oocyty ultrastruktura   MeSH
• prasata MeSH
• zvířata MeSH
• Check Tag
• ženské pohlaví MeSH
• zvířata MeSH

The oocyte GV/GVs (germinal vesicle/germinal vesicles) and zygot PN/PNs (pronucleus/pronuclei) of some mammals contain clearly visible nucleoli which exhibit an atypical morphological structure. These nucleoli (NCLs) can be relatively easily manipulated, i.e. removed from GVs/PNs or eventually transferred into another oocyte/zygote. Thus, with the help of micromanipulation techniques it was possible to uncover the real function(s) they play in processes of oocyte maturation and early embryonic development. The purpose of our review is to describe briefly the micromanipulation techniques that can be used for oocyte/zygote nucleoli manipulation. Moreover, we present some examples of results that were obtained in nucleolus manipulation experiments.

• MeSH
• buněčné jadérko metabolismus   transplantace   MeSH
• mikromanipulace metody   MeSH
• myši MeSH
• oocyty cytologie   účinky léků   MeSH
• partenogeneze MeSH
• prasata MeSH
• zvířata MeSH
• zygota cytologie   MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

It is well known that nucleoli of fully grown mammalian oocytes are indispensable for embryonic development. Therefore, the embryos originated from previously enucleolated (ENL) oocytes undergo only one or two cleavages and then their development ceases. In our study the interspecies (mouse/pig) nucleolus transferred embryos (NuTE) were produced and their embryonic development was analyzed by autoradiography, transmission electron microscopy (TEM) and immunofluorescence (C23 and upstream binding factor (UBF)). Our results show that the re-injection of isolated oocyte nucleoli, either from the pig (P + P) or mouse (P + M), into previously enucleolated and subsequently matured porcine oocytes rescues their development after parthenogenetic activation and some of these develop up to the blastocyst stage (P + P, 11.8%; P + M, 13.5%). In nucleolus re-injected 8-cell and blastocyst stage embryos the number of nucleoli labeled with C23 in P + P and P + M groups was lower than in control (non-manipulated) group. UBF was localized in small foci within the nucleoli of blastocysts in control and P + P embryos, however, in P + M embryos the labeling was evenly distributed in the nucleoplasm. The TEM and autoradiographic evaluations showed the formation of functional nucleoli and de novo rRNA synthesis at the 8-cell stage in both, control and P + P group. In the P + M group the formation of comparable nucleoli was delayed. In conclusion, our results indicate that the mouse nucleolus can rescue embryonic development of enucleolated porcine oocytes, but the localization of selected nucleolar proteins, the timing of transcription activation and the formation of the functional nucleoli in NuTE compared with control group show evident aberrations.

• MeSH
• blastocysta cytologie   metabolismus   MeSH
• buněčné jadérko fyziologie   transplantace   MeSH
• embryo savčí cytologie   metabolismus   MeSH
• embryonální vývoj fyziologie   MeSH
• klonování organismů MeSH
• myši MeSH
• oocyty cytologie   fyziologie   MeSH
• oogeneze fyziologie   MeSH
• prasata MeSH
• přenos embrya MeSH
• těhotenství MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• těhotenství MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

The large, compact oocyte nucleoli, sometimes referred to as nucleolus precursor bodies (NPBs), are essential for embryonic development in mammals; in their absence, the oocytes complete maturation and can be fertilized, but no nucleoli are formed in the zygote or embryo, leading to developmental failure. It has been convincingly documented that zygotes inherit the oocyte nucleolar material and form NPBs again in pronuclei. It is commonly accepted that during early embryonic development, the original compact zygote NPBs gradually transform into reticulated nucleoli of somatic cells. Here, we show that zygote NPBs are not required for embryonic and full-term development in the mouse. When NPBs were removed from late-stage zygotes by micromanipulation, the enucleolated zygotes developed to the blastocyst stage and, after transfer to recipients, live pups were obtained. We also describe de novo formation of nucleoli in developing embryos. After removal of NPBs from zygotes, they formed new nucleoli after several divisions. These results indicate that the zygote NPBs are not used in embryonic development and that the nucleoli in developing embryos originate from de novo synthesized materials.

• MeSH
• blastocysta cytologie   MeSH
• buněčné dělení MeSH
• buněčné jadérko fyziologie   MeSH
• buňky NIH 3T3 MeSH
• kultivace embrya MeSH
• kumulární buňky cytologie   MeSH
• mikromanipulace MeSH
• myši inbrední C57BL MeSH
• myši inbrední DBA MeSH
• myši inbrední ICR MeSH
• myši MeSH
• oocyty cytologie   MeSH
• přenos embrya MeSH
• těhotenství MeSH
• zvířata MeSH
• zygota růst a vývoj   MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• těhotenství MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Mammalian oocytes/zygotes contain atypical nucleoli that are composed exclusively of a dense fibrillar material. It has been commonly accepted that these nucleoli serve as a repository of components that are used later on, as the embryo develops, for the construction of typical tripartite nucleoli. Indeed, when nucleoli were removed from immature oocytes (enucleolation) and these oocytes were then matured, fertilized or parthenogenetically activated, development of the produced embryos ceased after one or two cleavages with no detectable nucleoli in nuclei. This indicated that zygotic nucleoli originate exclusively from oocytes, i.e. are maternally inherited. Recently published results, however, do not support this developmental biology dogma and demonstrate that maternal nucleoli in one-cell stage embryos are necessary only during a very short time period after fertilization when they serve as a major heterochromatin organizing structures. Nevertheless, it still remains to be determined, which other functions/roles the atypical oocyte/zygote nucleoli eventually have.

• MeSH
• buněčné jadérko fyziologie   MeSH
• časové faktory MeSH
• embryo savčí MeSH
• embryonální vývoj MeSH
• fertilizace MeSH
• heterochromatin fyziologie   MeSH
• lidé MeSH
• maternální dědičnost MeSH
• myši MeSH
• nukleoplasminy genetika   MeSH
• oocyty fyziologie   ultrastruktura   MeSH
• zvířata MeSH
• zygota fyziologie   MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

The oocyte (maternal) nucleolus is essential for early embryonic development and embryos originating from enucleolated oocytes arrest at the 2-cell stage. The reason for this is unclear. Surprisingly, RNA polymerase I activity in nucleolus-less mouse embryos, as manifested by pre-rRNA synthesis, and pre-rRNA processing are not affected, indicating an unusual role of the nucleolus. We report here that the maternal nucleolus is indispensable for the regulation of major and minor satellite repeats soon after fertilisation. During the first embryonic cell cycle, absence of the nucleolus causes a significant reduction in major and minor satellite DNA by 12% and 18%, respectively. The expression of satellite transcripts is also affected, being reduced by more than half. Moreover, extensive chromosome bridging of the major and minor satellite sequences was observed during the first mitosis. Finally, we show that the absence of the maternal nucleolus alters S-phase dynamics and causes abnormal deposition of the H3.3 histone chaperone DAXX in pronuclei of nucleolus-less zygotes.

• MeSH
• blastocysta cytologie   metabolismus   MeSH
• buněčné jadérko metabolismus   MeSH
• centromera metabolismus   MeSH
• embryo savčí cytologie   metabolismus   MeSH
• genetická transkripce MeSH
• genom genetika   MeSH
• heterochromatin genetika   MeSH
• messenger RNA genetika   metabolismus   MeSH
• mikrosatelitní repetice genetika   MeSH
• minisatelitní repetice genetika   MeSH
• myši MeSH
• oocyty cytologie   metabolismus   MeSH
• posttranskripční úpravy RNA genetika   MeSH
• prekurzory RNA genetika   MeSH
• rekombinace genetická genetika   MeSH
• replikace DNA genetika   MeSH
• restrukturace chromatinu genetika   MeSH
• RNA ribozomální biosyntéza   genetika   MeSH
• S fáze genetika   MeSH
• savčí chromozomy metabolismus   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH