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Fu B, Ma H, Liu D. Essential roles of the nucleolus during early embryonic development: a regulatory hub for chromatin organization. Open Biol 2024; 14:230358. [PMID: 38689555 PMCID: PMC11065130 DOI: 10.1098/rsob.230358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 12/26/2023] [Accepted: 03/15/2024] [Indexed: 05/02/2024] Open
Abstract
The nucleolus is the most prominent liquid droplet-like membrane-less organelle in mammalian cells. Unlike the nucleolus in terminally differentiated somatic cells, those in totipotent cells, such as murine zygotes or two-cell embryos, have a unique nucleolar structure known as nucleolus precursor bodies (NPBs). Previously, it was widely accepted that NPBs in zygotes are simply passive repositories of materials that will be gradually used to construct a fully functional nucleolus after zygotic genome activation (ZGA). However, recent research studies have challenged this simplistic view and demonstrated that functions of the NPBs go beyond ribosome biogenesis. In this review, we provide a snapshot of the functions of NPBs in zygotes and early two-cell embryos in mice. We propose that these membrane-less organelles function as a regulatory hub for chromatin organization. On the one hand, NPBs provide the structural platform for centric and pericentric chromatin remodelling. On the other hand, the dynamic changes in nucleolar structure control the release of the pioneer factors (i.e. double homeobox (Dux)). It appears that during transition from totipotency to pluripotency, decline of totipotency and initiation of fully functional nucleolus formation are not independent events but are interconnected. Consequently, it is reasonable to hypothesize that dissecting more unknown functions of NPBs may shed more light on the enigmas of early embryonic development and may ultimately provide novel approaches to improve reprogramming efficiency.
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Affiliation(s)
- Bo Fu
- Institute of Animal Husbandry, HeiLongJiang Academy of
Agricultural Sciences, Harbin150086, People's Republic of China
- Key Laboratory of Combining Farming and Animal Husbandry,
Ministry of Agriculture and Rural Affairs, Harbin150086, People's Republic of China
| | - Hong Ma
- Institute of Animal Husbandry, HeiLongJiang Academy of
Agricultural Sciences, Harbin150086, People's Republic of China
- Key Laboratory of Combining Farming and Animal Husbandry,
Ministry of Agriculture and Rural Affairs, Harbin150086, People's Republic of China
| | - Di Liu
- Institute of Animal Husbandry, HeiLongJiang Academy of
Agricultural Sciences, Harbin150086, People's Republic of China
- Key Laboratory of Combining Farming and Animal Husbandry,
Ministry of Agriculture and Rural Affairs, Harbin150086, People's Republic of China
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2
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Bogolyubova I, Salimov D, Bogolyubov D. Chromatin Configuration in Diplotene Mouse and Human Oocytes during the Period of Transcriptional Activity Extinction. Int J Mol Sci 2023; 24:11517. [PMID: 37511273 PMCID: PMC10380668 DOI: 10.3390/ijms241411517] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 07/10/2023] [Accepted: 07/12/2023] [Indexed: 07/30/2023] Open
Abstract
In the oocyte nucleus, called the germinal vesicle (GV) at the prolonged diplotene stage of the meiotic prophase, chromatin undergoes a global rearrangement, which is often accompanied by the cessation of its transcriptional activity. In many mammals, including mice and humans, chromatin condenses around a special nuclear organelle called the atypical nucleolus or formerly nucleolus-like body. Chromatin configuration is an important indicator of the quality of GV oocytes and largely predicts their ability to resume meiosis and successful embryonic development. In mice, GV oocytes are traditionally divided into the NSN (non-surrounded nucleolus) and SN (surrounded nucleolus) based on the specific chromatin configuration. The NSN-SN transition is a key event in mouse oogenesis and the main prerequisite for the normal development of the embryo. As for humans, there is no single nomenclature for the chromatin configuration at the GV stage. This often leads to discrepancies and misunderstandings, the overcoming of which should expand the scope of the application of mouse oocytes as a model for developing new methods for assessing and improving the quality of human oocytes. As a first approximation and with a certain proviso, the mouse NSN/SN classification can be used for the primary characterization of human GV oocytes. The task of this review is to analyze and discuss the existing classifications of chromatin configuration in mouse and human GV oocytes with an emphasis on transcriptional activity extinction at the end of oocyte growth.
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Affiliation(s)
- Irina Bogolyubova
- Institute of Cytology of the Russian Academy of Sciences, 194064 St. Petersburg, Russia
| | - Daniil Salimov
- Clinical Institute of Reproductive Medicine, 620014 Yekaterinburg, Russia
| | - Dmitry Bogolyubov
- Institute of Cytology of the Russian Academy of Sciences, 194064 St. Petersburg, Russia
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Benc M, Strejcek F, Morovic M, Bartkova A, Murin M, Gad A, Bonnet-Garnier A, Percinic FP, Laurincik J. Improving the Quality of Oocytes with the Help of Nucleolotransfer Therapy. Pharmaceuticals (Basel) 2021; 14:ph14040328. [PMID: 33918523 PMCID: PMC8066131 DOI: 10.3390/ph14040328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 03/26/2021] [Accepted: 03/29/2021] [Indexed: 11/16/2022] Open
Abstract
The nucleolus is an important nucleus sub-organelle found in almost all eukaryotic cells. On the one hand, it is known as a differentiated active site of ribosome biogenesis in somatic cells, but on the other hand, in fully grown oocytes, zygotes, and early embryos (up to the major embryonic genome activation), it is in the form of a particular homogenous and compact structure called a fibrillar sphere. Nowadays, thanks to recent studies, we know many important functions of this, no doubt, interesting membraneless nucleus sub-organelle involved in oocyte maturation, embryonic genome activation, rRNA synthesis, etc. However, many questions are still unexplained and remain a mystery. Our aim is to create a comprehensive overview of the recent knowledge on the fibrillar sphere and envision how this knowledge could be utilized in further research in the field of biotechnology and nucleolotransfer therapy.
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Affiliation(s)
- Michal Benc
- Faculty of Natural Sciences, Constantine the Philosopher University in Nitra, Nabrezie mladeze 91, 94974 Nitra, Slovakia; (M.B.); (M.M.); (A.B.); (J.L.)
| | - Frantisek Strejcek
- Faculty of Natural Sciences, Constantine the Philosopher University in Nitra, Nabrezie mladeze 91, 94974 Nitra, Slovakia; (M.B.); (M.M.); (A.B.); (J.L.)
- Correspondence: ; Tel.: +421-037-6408-584
| | - Martin Morovic
- Faculty of Natural Sciences, Constantine the Philosopher University in Nitra, Nabrezie mladeze 91, 94974 Nitra, Slovakia; (M.B.); (M.M.); (A.B.); (J.L.)
| | - Alexandra Bartkova
- Faculty of Natural Sciences, Constantine the Philosopher University in Nitra, Nabrezie mladeze 91, 94974 Nitra, Slovakia; (M.B.); (M.M.); (A.B.); (J.L.)
- Institute of Animal Physiology and Genetics, The Czech Academy of Sciences, 27721 Libechov, Czech Republic; (M.M.); (A.G.)
| | - Matej Murin
- Institute of Animal Physiology and Genetics, The Czech Academy of Sciences, 27721 Libechov, Czech Republic; (M.M.); (A.G.)
| | - Ahmed Gad
- Institute of Animal Physiology and Genetics, The Czech Academy of Sciences, 27721 Libechov, Czech Republic; (M.M.); (A.G.)
| | - Amelie Bonnet-Garnier
- Université Paris-Saclay, UVSQ, INRAE, BREED, 78350 Jouy-en-Josas, France;
- Ecole Nationale Vétérinaire d’Alfort, BREED, 94700 Maisons-Alfort, France
| | - Florina Popovska Percinic
- Faculty of Veterinary Medicine, St. Cyril and Methodius University in Skopje, 1000 Skopje, North Macedonia;
| | - Jozef Laurincik
- Faculty of Natural Sciences, Constantine the Philosopher University in Nitra, Nabrezie mladeze 91, 94974 Nitra, Slovakia; (M.B.); (M.M.); (A.B.); (J.L.)
- Institute of Animal Physiology and Genetics, The Czech Academy of Sciences, 27721 Libechov, Czech Republic; (M.M.); (A.G.)
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The nucleolus-like and precursor bodies of mammalian oocytes and embryos and their possible role in post-fertilization centromere remodelling. Biochem Soc Trans 2021; 48:581-593. [PMID: 32318710 DOI: 10.1042/bst20190847] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 03/27/2020] [Accepted: 03/30/2020] [Indexed: 12/14/2022]
Abstract
In nearly all somatic cells, the ribosome biosynthesis is a key activity. The same is true also for mammalian oocytes and early embryos. This activity is intimately linked to the most prominent nuclear organelles - the nucleoli. Interestingly, during a short period around fertilization, the nucleoli in oocytes and embryos transform into ribosome-biosynthesis-inactive structures termed nucleolus-like or nucleolus precursor bodies (NPBs). For decades, researchers considered these structures to be passive repositories of nucleolar proteins used by the developing embryo to rebuild fully functional, ribosome-synthesis competent nucleoli when required. Recent evidence, however, indicates that while these structures are unquestionably essential for development, the material is largely dispensable for the formation of active embryonic nucleoli. In this mini-review, we will describe some unique features of oocytes and embryos with respect to ribosome biogenesis and the changes in the structure of oocyte and embryonic nucleoli that reflect this. We will also describe some of the different approaches that can be used to study nucleoli and NPBs in embryos and discuss the different results that might be expected. Finally, we ask whether the main function of nucleolar precursor bodies might lie in the genome organization and remodelling and what the involved components might be.
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Intranuclear characteristics of pig oocytes stained with brilliant cresyl blue and nucleologenesis of resulting embryos. ZYGOTE 2019; 27:232-240. [PMID: 31397243 DOI: 10.1017/s0967199419000352] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Brilliant cresyl blue (BCB) vital labelling is a powerful method for analyzing the quality of porcine cumulus-oocyte complexes. Our aim was to investigate the correlation between the selection of porcine oocytes using BCB labelling and selected intranuclear characteristics of porcine oocytes and parthenotes. Moreover, BCB labelling was correlated with the diameter of the oocyte and the developmental potential of the parthenotes. The following methods were used: BCB labelling, measurement of the diameter of the oocyte, parthenogenetic activation, immunocytochemistry, transmission electron microscopy, enucleation and relative protein concentration (RPC) analysis. We determined that the diameter of the oocytes in the BCB-positive (BCB+) group was significantly larger than in the BCB-negative (BCB-) group. Immediately after oocyte selection according to BCB labelling, we found significant difference in chromatin configuration between the analyzed groups. BCB+ oocytes were significantly better at maturation than BCB- oocytes. BCB+ embryos were significantly more competent at cleaving and in their ability to reach the blastocyst stage than BCB- embryos. Ultrastructural analyses showed that the formation of active nucleoli in the BCB+ group started at the 8-cell stage. Conversely, most BCB- embryos at the 8-cell and 16-cell stages were fragmented. No statistically significant difference in RPC in nucleolus precursor bodies (NPBs) between BCB+ and BCB- oocytes was found. We can conclude that BCB labelling could be suitable for assessing the quality of porcine oocytes. Moreover, the evaluation of RPC indicates that the quantitative content of proteins in NPB is already established in growing oocytes.
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Fulka H, Langerova A. Nucleoli in embryos: a central structural platform for embryonic chromatin remodeling? Chromosome Res 2018; 27:129-140. [PMID: 30406864 DOI: 10.1007/s10577-018-9590-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 10/17/2018] [Accepted: 10/24/2018] [Indexed: 10/27/2022]
Abstract
Nucleoli are the site of ribosomal RNA production and subunit assembly. In contrast to active nucleoli in somatic cells, where three basic sub-compartments can be observed, mammalian oocytes and early embryos contain atypical nucleoli termed "nucleolus-like bodies" or "nucleolus precursor bodies", respectively. Unlike their somatic counterparts, these structures are composed of dense homogenous fibrillar material and exhibit no polymerase activity. Irrespective of these unusual properties, they have been shown to be absolutely essential for embryonic development, as their microsurgical removal results in developmental arrest. Historically, nucleolus-like and nucleolus precursor bodies have been perceived as passive storage sites of nucleolar material, which is gradually utilized by embryos to construct fully functional nucleoli once they have activated their genome and have started to produce ribosomes. For decades, researchers have been trying to elucidate the composition of these organelles and provide the evidence for their repository role. However, only recently has it become clear that the function of these atypical nucleoli is altogether different, and rather than being involved in ribosome biogenesis, they participate in parental chromatin remodeling, and strikingly, the artificial introduction of a single NPB component is sufficient to rescue the developmental arrest elicited by the NPB removal. In this review, we will describe and summarize the experiments that led to the change in our understanding of these unique structures.
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Affiliation(s)
- Helena Fulka
- Institute of Animal Science, v.v.i., 104 00, Prague 10, Czech Republic. .,Institute of Molecular Genetics ASCR, v.v.i., 142 20, Prague 4, Czech Republic. .,Institute of Experimental Medicine ASCR, v.v.i., 142 20, Prague 4, Czech Republic.
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Kyogoku H, Wakayama T, Kitajima TS, Miyano T. Single nucleolus precursor body formation in the pronucleus of mouse zygotes and SCNT embryos. PLoS One 2018; 13:e0202663. [PMID: 30125305 PMCID: PMC6101414 DOI: 10.1371/journal.pone.0202663] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 08/07/2018] [Indexed: 11/18/2022] Open
Abstract
Mammalian oocytes and zygotes have nucleoli that are transcriptionally inactive and structurally distinct from nucleoli in somatic cells. These nucleoli have been termed nucleolus precursor bodies (NPBs). Recent research has shown that NPBs are important for embryonic development, but they are only required during pronuclear formation. After fertilization, multiple small NPBs are transiently formed in male and female pronuclei and then fuse into a single large NPB in zygotes. In cloned embryos produced by somatic cell nuclear transfer (SCNT), multiple NPBs are formed and maintained in the pseudo-pronucleus, and this is considered an abnormality of the cloned embryos. Despite this difference between SCNT and normal embryos, it is unclear how the size and number of NPBs in pronuclei is determined. Here, we show that in mouse embryos, the volume of NPB materials plays a major role in the NPB scaling through a limiting component mechanism and determines whether a single or multiple NPBs will form in the pronucleus. Extra NPB- and extra MII spindle-injection experiments demonstrated that the total volume of NPBs was maintained regardless of the pronucleus number and the ratio of pronucleus/NPB is important for fusion into a single NPB. Based on these results, we examined whether extra-NPB injection rescued multiple NPB maintenance in SCNT embryos. When extra-NPBs were injected into enucleated-MII oocytes before SCNT, the number of NPBs in pseudo-pronuclei of SCNT embryos was reduced. These results indicate that multiple NPB maintenance in SCNT embryos is caused by insufficient volume of NPB.
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Affiliation(s)
- Hirohisa Kyogoku
- Graduate School of Agricultural Science, Kobe University, Kobe, Japan
- Laboratory for Chromosome Segregation, Center for Developmental Biology, RIKEN, Kobe, Japan
- Laboratory for Chromosome Segregation, RIKEN Center for Biosystems Dynamics Research, Kobe, Japan
- * E-mail:
| | - Teruhiko Wakayama
- Faculty of Life and Environmental Sciences, University of Yamanashi, Kofu, Japan
| | - Tomoya S. Kitajima
- Laboratory for Chromosome Segregation, Center for Developmental Biology, RIKEN, Kobe, Japan
- Laboratory for Chromosome Segregation, RIKEN Center for Biosystems Dynamics Research, Kobe, Japan
| | - Takashi Miyano
- Graduate School of Agricultural Science, Kobe University, Kobe, Japan
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Benc M, Strejcek F, Murin M, Morovic M, Martinkova S, Jettmarova D, Pendovski L, Fulka J, Laurincik J. Nucleologenesis and Nucleolotransfer in Mammalian Oocytes: A Review. MACEDONIAN VETERINARY REVIEW 2017. [DOI: 10.1515/macvetrev-2017-0023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
An effort to improve development potential of early embryos is one of the main goals of biotechnology in the area of reproductive biology with application in veterinary or human medicine. Recent observations of the function of nucleolus or rather its forms before, during and after the fertilisation or parthenogenetic activation show the key role(s) of nucleolus in the processes of early genome activation. The nucleolus is a subnuclear structure (organelle) mainly involved in regulation of transcription and translation. This organelle has been characterized in detail by immunofluorescence, cell transfection and proteomics. This data was, however, mostly obtained in nucleoli of differentiated eukaryotic cells. Much less is known about the nucleolar structural changes and related functional processes in growing and fully grown mammalian oocytes, zygotes and early cleavage stage embryos, especially in the context of embryonic genome activation. It has been shown, that nucleoli in mammalian oocytes and early embryos have several forms and functions, which vary during the oocyte growth and embryonic development. Certain functions have not been fully described or explained, yet. The method of enucleolation, which allows to remove nucleoli from the oocytes or to exchange nucleoli between oocytes or zygotes, together with their proteomic and structural analyses brought new information about functions of nucleoli in oocytes and early cleavage-stage embryos and allowed to explain some new key roles of nucleoli during oocyte maturation and early embryonic development.
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Affiliation(s)
- Michal Benc
- Department of Zoology and Anthropology, Faculty of Natural Sciences , Constantine the Philosopher University in Nitra , Nabrezie mladeze 91, 949 74 Nitra , Slovak Republic
- Institute of Animal Science , Pratelstvi 815, 104 00 Prague - Uhrineves, Czech Republic
| | - Frantisek Strejcek
- Department of Botany and Genetics, Faculty of Natural Sciences , Constantine the Philosopher University in Nitra , Nabrezie mladeze 91, 949 74 Nitra , Slovak Republic
| | - Matej Murin
- Department of Botany and Genetics, Faculty of Natural Sciences , Constantine the Philosopher University in Nitra , Nabrezie mladeze 91, 949 74 Nitra , Slovak Republic
| | - Martin Morovic
- Department of Botany and Genetics, Faculty of Natural Sciences , Constantine the Philosopher University in Nitra , Nabrezie mladeze 91, 949 74 Nitra , Slovak Republic
| | - Stanislava Martinkova
- Institute of Animal Science , Pratelstvi 815, 104 00 Prague - Uhrineves, Czech Republic
| | - Dominika Jettmarova
- Institute of Animal Science , Pratelstvi 815, 104 00 Prague - Uhrineves, Czech Republic
| | - Lazo Pendovski
- Faculty of Veterinary Medicine-Skopje , Ss. Cyril and Methodius University in Skopje , st. Lazar Pop-Trajkov 5-7, 1000 Skopje , Macedonia (the former Yugoslav Republic of)
| | - Josef Fulka
- Institute of Animal Science , Pratelstvi 815, 104 00 Prague - Uhrineves, Czech Republic
| | - Jozef Laurincik
- Department of Zoology and Anthropology, Faculty of Natural Sciences , Constantine the Philosopher University in Nitra , Nabrezie mladeze 91, 949 74 Nitra , Slovak Republic
- Institute of Animal Physiology and Genetics AS CR , Rumburska 89, 277 21 Libechov , Czech Republic
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Fulka H, Aoki F. Nucleolus Precursor Bodies and Ribosome Biogenesis in Early Mammalian Embryos: Old Theories and New Discoveries. Biol Reprod 2016; 94:143. [PMID: 26935600 DOI: 10.1095/biolreprod.115.136093] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 02/22/2016] [Indexed: 11/01/2022] Open
Abstract
In mammals, mature oocytes and early preimplantation embryos contain transcriptionally inactive structures termed nucleolus precursor bodies instead of the typical fibrillo-granular nucleoli. These nuclear organelles are essential and strictly of maternal origin. If they are removed from oocytes, the resulting embryos are unable to replace them and consequently fail to develop. Historically, nucleolus precursor bodies have been perceived as a passive repository site of nucleolar proteins that are required for embryos to form fully functional nucleoli. Recent results, however, contradict this long-standing dogma and show that these organelles are dispensable for nucleologenesis and ribosome biogenesis. In this article, we discuss the possible roles of nucleolus precursor bodies and propose how they might be involved in embryogenesis. Furthermore, we argue that these organelles are essential only shortly after fertilization and suggest that they might actively participate in centromeric chromatin establishment.
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Affiliation(s)
- Helena Fulka
- Institute of Animal Science, Prague, Czech Republic Institute of Molecular Genetics of the ASCR, Prague, Czech Republic
| | - Fugaku Aoki
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba, Japan
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Fulka H, Kyogoku H, Zatsepina O, Langerova A, Fulka J. Can Nucleoli Be Markers of Developmental Potential in Human Zygotes? Trends Mol Med 2015; 21:663-672. [DOI: 10.1016/j.molmed.2015.09.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 09/18/2015] [Accepted: 09/18/2015] [Indexed: 01/10/2023]
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Shishova KV, Khodarovich YM, Lavrentyeva EA, Zatsepina OV. High-resolution microscopy of active ribosomal genes and key members of the rRNA processing machinery inside nucleolus-like bodies of fully-grown mouse oocytes. Exp Cell Res 2015; 337:208-18. [PMID: 26226217 DOI: 10.1016/j.yexcr.2015.07.024] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Revised: 07/23/2015] [Accepted: 07/25/2015] [Indexed: 11/29/2022]
Abstract
Nucleolus-like bodies (NLBs) of fully-grown (germinal vesicle, GV) mammalian oocytes are traditionally considered as morphologically distinct entities, which, unlike normal nucleoli, contain transcribed ribosomal genes (rDNA) solely at their surface. In the current study, we for the first time showed that active ribosomal genes are present not only on the surface but also inside NLBs of the NSN-type oocytes. The "internal" rRNA synthesis was evidenced by cytoplasmic microinjections of BrUTP as precursor and by fluorescence in situ hybridization with a probe to the short-lived 5'ETS segment of the 47S pre-rRNA. We further showed that in the NLB mass of NSN-oocytes, distribution of active rDNA, RNA polymerase I (UBF) and rRNA processing (fibrillarin) protein factors, U3 snoRNA, pre-rRNAs and 18S/28S rRNAs is remarkably similar to that in somatic nucleoli capable to make pre-ribosomes. Overall, these observations support the occurrence of rDNA transcription, rRNA processing and pre-ribosome assembly in the NSN-type NLBs and so that their functional similarity to normal nucleoli. Unlike the NSN-type NLBs, the NLBs of more mature SN-oocytes do not contain transcribed rRNA genes, U3 snoRNA, pre-rRNAs, 18S and 28S rRNAs. These results favor the idea that in a process of transformation of NSN-oocytes to SN-oocytes, NLBs cease to produce pre-ribosomes and, moreover, lose their rRNAs. We also concluded that a denaturing fixative 70% ethanol used in the study to fix oocytes could be more appropriate for light microscopy analysis of nucleolar RNAs and proteins in mammalian fully-grown oocytes than a commonly used cross-linking aldehyde fixative, formalin.
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Affiliation(s)
- Kseniya V Shishova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street, 16/10, 117997 Moscow, Russian Federation.
| | - Yuriy M Khodarovich
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street, 16/10, 117997 Moscow, Russian Federation.
| | - Elena A Lavrentyeva
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street, 16/10, 117997 Moscow, Russian Federation; Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, GSP-1, Leninskiye Gory, MSU, 1-73, Office 433, 119991 Moscow, Russian Federation.
| | - Olga V Zatsepina
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street, 16/10, 117997 Moscow, Russian Federation.
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Shishova KV, Khodarovich YM, Lavrentyeva EA, Zatsepina OV. Analysis of the localization of fibrillarin and sites of pre-rRNA synthesis in the nucleolus-like bodies of mouse GV oocytes after mild treatment with proteinase K. Russ J Dev Biol 2015. [DOI: 10.1134/s1062360415030066] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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13
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Nobata T, Kyougoku H, Miyano T. Hematoxylin staining reveals a decrease in nucleolar diameter of pig oocytes before germinal vesicle breakdown. J Reprod Dev 2013; 59:500-5. [PMID: 23856597 PMCID: PMC3934123 DOI: 10.1262/jrd.2012-182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
During oocyte growth, the morphology of the nucleolus changes into a compact and homogenous structure. The compact nucleoli in full-grown oocytes are not stained by aceto-orcein staining or immunofluorescence staining. In this study, we developed a hematoxylin staining method for pig oocytes in whole-mount preparations to visualize the nucleoli. Nucleoli of growing and full-grown oocytes were stained blue with hematoxylin. Using this staining method, the changes in the oocyte nucleolus during maturation were examined. The nucleolar diameter gradually decreased in maturing oocytes (10.7 ± 0.1 μm to 9.0 ± 0.7 μm, P<0.05) before germinal vesicle breakdown (GVBD). The results suggest that the nucleolar volume of oocytes decreases before GVBD.
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Affiliation(s)
- Tadatoshi Nobata
- Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan
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Kyogoku H, Ogushi S, Miyano T. Nucleoli from two-cell embryos support the development of enucleolated germinal vesicle oocytes in the pig. Biol Reprod 2012; 87:113. [PMID: 22976279 DOI: 10.1095/biolreprod.112.103119] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Recent research has shown that nucleoli of oocytes at the germinal vesicle (GV) stage (GV nucleoli) are not necessary for oocyte maturation but are essential for early embryonic development. Nucleoli of 2-cell embryos (2-cell nucleoli) have morphology similar to that of nucleoli in oocytes at the GV stage. In this study, we examined the ability of 2-cell nucleoli to substitute for GV nucleoli in terms of supporting early embryonic development by nucleolus aspiration (enucleolation) and transfer into metaphase II (MII) oocytes or 2-cell embryos that were derived from enucleolated oocytes at the GV stage in the pig. When 2-cell embryos were centrifuged to move the lipid droplets to one side of the blastomere, multiple nucleoli in the nucleus fused into a single nucleolus. The nucleoli were then aspirated from the 2-cell embryos by micromanipulation. The injection of 2-cell nucleoli to GV enucleolated oocytes at the MII stage rescued the embryos from the early embryonic arrest, and the resulting oocytes developed to blastocysts. However, the injection of 2-cell and GV nucleoli to 2-cell embryos derived from GV enucleolated oocytes rarely restored the development to blastocysts. These results indicate that 2-cell nucleoli support early embryonic development as GV nucleoli and that the presence of nucleoli is essential for pig embryos before the 2-cell stage.
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Affiliation(s)
- Hirohisa Kyogoku
- Graduate School of Agricultural Science, Kobe University, Kobe, Japan.
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