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Xie H, Linning-Duffy K, Demireva EY, Toh H, Abolibdeh B, Shi J, Zhou B, Iwase S, Yan L. CRISPR-based genome editing of a diurnal rodent, Nile grass rat (Arvicanthis niloticus). BMC Biol 2024; 22:144. [PMID: 38956550 PMCID: PMC11218167 DOI: 10.1186/s12915-024-01943-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Accepted: 06/21/2024] [Indexed: 07/04/2024] Open
Abstract
BACKGROUND Diurnal and nocturnal mammals have evolved distinct pathways to optimize survival for their chronotype-specific lifestyles. Conventional rodent models, being nocturnal, may not sufficiently recapitulate the biology of diurnal humans in health and disease. Although diurnal rodents are potentially advantageous for translational research, until recently, they have not been genetically tractable. The present study aims to address this major limitation by developing experimental procedures necessary for genome editing in a well-established diurnal rodent model, the Nile grass rat (Arvicanthis niloticus). RESULTS A superovulation protocol was established, which yielded nearly 30 eggs per female grass rat. Fertilized eggs were cultured in a modified rat 1-cell embryo culture medium (mR1ECM), in which grass rat embryos developed from the 1-cell stage into blastocysts. A CRISPR-based approach was then used for gene editing in vivo and in vitro, targeting Retinoic acid-induced 1 (Rai1), the causal gene for Smith-Magenis Syndrome, a neurodevelopmental disorder. The CRISPR reagents were delivered in vivo by electroporation using an improved Genome-editing via Oviductal Nucleic Acids Delivery (i-GONAD) method. The in vivo approach produced several edited founder grass rats with Rai1 null mutations, which showed stable transmission of the targeted allele to the next generation. CRISPR reagents were also microinjected into 2-cell embryos in vitro. Large deletion of the Rai1 gene was confirmed in 70% of the embryos injected, demonstrating high-efficiency genome editing in vitro. CONCLUSION We have established a set of methods that enabled the first successful CRISPR-based genome editing in Nile grass rats. The methods developed will guide future genome editing of this and other diurnal rodent species, which will promote greater utility of these models in basic and translational research.
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Affiliation(s)
- Huirong Xie
- Transgenic and Genome Editing Facility, Institute for Quantitative Health Science & Engineering, Research Technology Support Facility, Michigan State University, East Lansing, MI, 48824, USA.
| | | | - Elena Y Demireva
- Transgenic and Genome Editing Facility, Institute for Quantitative Health Science & Engineering, Research Technology Support Facility, Michigan State University, East Lansing, MI, 48824, USA
| | - Huishi Toh
- Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, USA
| | - Bana Abolibdeh
- Transgenic and Genome Editing Facility, Institute for Quantitative Health Science & Engineering, Research Technology Support Facility, Michigan State University, East Lansing, MI, 48824, USA
| | - Jiaming Shi
- Department of Psychology, Michigan State University, East Lansing, MI, 48824, USA
| | - Bo Zhou
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, USA
- Department of Pediatrics, University of Michigan Medical School, Ann Arbor, USA
| | - Shigeki Iwase
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, USA
- Department of Pediatrics, University of Michigan Medical School, Ann Arbor, USA
| | - Lily Yan
- Department of Psychology, Michigan State University, East Lansing, MI, 48824, USA.
- Neuroscience Program, Michigan State University, East Lansing, USA.
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Xie H, Linning-Duffy K, Demireva EY, Toh H, Abolibdeh B, Shi J, Zhou B, Iwase S, Yan L. CRISPR-based Genome Editing of a Diurnal Rodent, Nile Grass Rat ( Arvicanthis niloticus). BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.23.553600. [PMID: 37662225 PMCID: PMC10473663 DOI: 10.1101/2023.08.23.553600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
Diurnal and nocturnal mammals have evolved distinct pathways to optimize survival for their chronotype-specific lifestyles. Conventional rodent models, being nocturnal, may not sufficiently recapitulate the biology of diurnal humans in health and disease. Although diurnal rodents are potentially advantageous for translational research, until recently, they have not been genetically tractable. Here, we address this major limitation by demonstrating the first successful CRISPR genome editing of the Nile grass rat ( Arvicanthis niloticus ), a valuable diurnal rodent. We establish methods for superovulation; embryo development, manipulation, and culture; and pregnancy maintenance to guide future genome editing of this and other diurnal rodent species.
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Abstract
The rat is one the most widely used laboratory animal species in many aspects of biomedical research, including the production of genetically engineered animal models to study human diseases and conditions. In addition to in vitro fertilization (IVF), the ability to grow IVF-derived or in vivo-collected zygotes to a desired preimplantation stage (zygote to blastocyst) entirely in vitro has a great importance for studies of developmental biology and genetic modification of laboratory rats for biomedical research. Although embryo biotechnologies are required to study or manipulate the genome effectively, such technologies for rat preimplantation embryos are not currently as successful as they are in the mouse. Here we provide a brief history of the development of rat in vitro culture systems and a step-by-step protocol to produce rat blastocyst stage embryos from zygotes under in vitro conditions from commonly used laboratory rat strains in biomedical research.
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Affiliation(s)
- Yuksel Agca
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, MO, USA.
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Molecular and ultrastuctural changes of rat pre-implantation embryos during two-cell developmental arrest. J Assist Reprod Genet 2015; 31:767-80. [PMID: 24658924 DOI: 10.1007/s10815-014-0213-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Accepted: 03/04/2014] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND Rat pre-implantation embryos often suffer 2-cell stage developmental arrest and fail to progress further under in-vitro conditions. OBJECTIVE In order to understand underlying mechanism leading to 2-cell arrest, we investigated the molecular changes, culture conditions and subcellular changes. METHODS Gene expression in in-vivo developed 2-cell embryos (in-vivo), in- vitro developed 2-cell embryos (in-vitro), and in-vitro 2-cell arrested embryos (arrested) were investigated using microarrays and real-time PCR. Ultra-structural changes were determined using electron microscopy. RESULTS Gene expression was similar between in-vivo and in-vitro embryos. Over 2400 genes changed in arrested embryos compared to in-vivo and in-vitro embryos. The mRNAs encoding proteins involved in translation were elevated in arrested embryos. In-vivo and in-vitro embryos highly expressed genes that were involved in cell cycle, and protein catabolic process compared to arrested embryos. Gene expression data suggested subcellular changes associated with 2-cell block. Transmission electron microscopy showed that in-vivo embryos had healthy subcellular structure, whereas arrested embryos did not have a nuclear membrane, contained small mitochondria and autophagic vacuoles. Furthermore, gene expression data was used for the optimization of culture media conditions to obtain better in-vitro embryonic development. Comparison of five and 20 % oxygen in culture resulted in two times more blastocyst formation with 5 % oxygen. CONCLUSIONS These results showed that although all experimental groups appeared morphologically similar, arrested embryos had ultra-structural and molecular changes associated with oxidative stress and apoptosis. In-vitro culture under low oxygen and media additives reduced 2-cell block in rat embryos.
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Interspecies somatic cell nucleus transfer with porcine oocytes as recipients: A novel bioassay system for assessing the competence of canine somatic cells to develop into embryos. Theriogenology 2009; 72:549-59. [DOI: 10.1016/j.theriogenology.2009.04.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2009] [Revised: 03/14/2009] [Accepted: 04/08/2009] [Indexed: 01/08/2023]
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Establishment of rat embryonic stem-like cells from the morula using a combination of feeder layers. ZYGOTE 2009; 17:229-37. [PMID: 19356268 DOI: 10.1017/s0967199409005280] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Embryonic stem (ES) cells are characterized by pluripotency, in particular the ability to form a germline on injection into blastocysts. Despite numerous attempts, ES cell lines derived from rat embryos have not yet been established. The reason for this is unclear, although certain intrinsic biological differences among species and/or strains have been reported. Herein, using Wistar-Imamichi rats, specific characteristics of preimplantation embryos are described. At the blastocyst stage, Oct4 (also called Pou5f1) was expressed in both the inner cell mass (ICM) and the trophectoderm (TE), whereas expression of Cdx2 was localized to the TE. In contrast, at an earlier stage, expression of Oct4 was detected in all the nuclei in the morula. These stages were examined using a combination of feeder layers (rat embryonic fibroblast [REF] for primary outgrowth and SIM mouse embryo-derived thioguanine- and ouabain-resistant [STO] cells for passaging) to establish rat ES-like cell lines. The rat ES-like cell lines obtained from the morula maintained expression of Oct4 over long-term culture, whereas cell lines derived from blastocysts lost pluripotency during early passage. The morula-derived ES-like cell lines showed Oct4 expression in a long-term culture, even after cryogenic preservation, thawing and EGFP transfection. These results indicate that rat ES-like cell lines with long-term Oct4 expression can be established from the morula of Wistar-Imamichi rats using a combination of feeder layers.
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Barceló-Fimbres M, Seidel GE. Effects of either glucose or fructose and metabolic regulators on bovine embryo development and lipid accumulation in vitro. Mol Reprod Dev 2007; 74:1406-18. [PMID: 17342742 DOI: 10.1002/mrd.20700] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Our objective was to determine if replacing glucose with fructose would decrease cytoplasmic lipid accumulation during culture of embryos with or without regulators of metabolism. In vitro-produced bovine zygotes were cultured 60 hr in chemically defined medium-1 (CDM-1) plus 0.5% BSA and 0.5 mM fructose or glucose in Experiment 1, and glucose in Experiment 2. In both experiments, 8-cell embryos were next cultured 135 hr in CDM-2 plus 2 mM fructose or glucose in factorial combination with five treatments: (Experiment 1: control, 10% fetal calf serum (FCS), 0.3 microM phenazine ethosulfate (PES), 30 microM dinitrophenol (DNP), and PES + DNP), and (Experiment 2: control, PES, PES + DNP, and 1 and 3 microg/ml cerulenin (C1 and C3)). Day 7.5 blastocysts were stained with Sudan Black B to quantify cytoplasmic lipid droplets as small (SD, <2 microm), medium (MD, 2-6 microm), or large (LD, >6 microm). Blastocyst rates per oocyte were 22% (Experiment 1) and 15% (Experiment 2) higher (P < 0.05) for fructose than glucose. For Experiment 1, numbers of MD were lower for PES, DNP, and PES + DNP than control and FCS (P < 0.05). LD were lower for PES and DNP than control, and higher for FCS than all other treatments (P < 0.05). For Experiment 2, MD were lower (P < 0.05) for PES, and PES + DNP than C1, C3, and control. For LD, PES was lower (P < 0.05) than control, C1, and C3, but not different from PES + DNP. The only effect of hexose on lipids was that fructose resulted in fewer MD (P < 0.01) in Experiment 2. In conclusion, fructose produced more blastocysts than glucose, and PES reduced lipid accumulation.
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Affiliation(s)
- M Barceló-Fimbres
- Animal Reproduction and Biotechnology Laboratory, Colorado State University, Fort Collins, Colorado, USA
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Yoo JG, Demers SP, Lian L, Smith LC. Developmental Arrest and Cytoskeletal Anomalies of Rat Embryos Reconstructed by Somatic Cell Nuclear Transfer. CLONING AND STEM CELLS 2007; 9:382-93. [PMID: 17907949 DOI: 10.1089/clo.2006.0081] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Many factors influence success rates in animal cloning by somatic cell nuclear transfer (SCNT), including cell cycle stage of donor cells and recipient oocytes, the procedure of micromanipulation, and the activation protocol. This study was conducted to determine the effects of cell cycle coordination for cloning rats from fetal fibroblasts (FFs). Moreover, enucleated zygotic and parthenogenetic ooplasts were used for serial cloning with pronuclear and two-cell stage blastomeres derived from SCNT. Metaphase donor cells had a significantly higher cleavage rate than G0/G1-phase FFs with MII oocytes and G2-phase FFs with TII oocytes. However, reconstructed embryos were unable to develop beyond the two-cell stage, neither in vitro nor in vivo. Moreover, the developmental arrest at the two-cell stage was not overcome, even when using serial cloning with zygotic and parthenogenetic recipients. To assess the cytoskeleton after SCNT, reconstructed two-cell stage embryos were harvested at different times after cleavage for immunostaining (anti-alpha-tubulin) and mRNA abundance (beta-actin, alpha-tubulin, alpha-actinin). Reconstructed two-cell embryos showed abnormal microtubule distribution and down-regulated expression of several cytoskeletal transcripts. Therefore, it seems that the developmental arrest of rat SCNT embryos is associated with improper transcription of cytoskeleton genes, presumably resulting in abnormal microtubule distribution.
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Affiliation(s)
- Jae Gyu Yoo
- Centre de recherche en reproduction animale (CRRA), Faculté de médecine vétérinarie, Université de Montréal, Saint-Hyacinthe, QC, Canada
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Shinozawa T, Mizutani E, Tomioka I, Kawahara M, Sasada H, Matsumoto H, Sato E. Differential effect of recipient cytoplasm for microtubule organization and preimplantation development in rat reconstituted embryos with two-cell embryonic cell nuclear transfer. Mol Reprod Dev 2005; 68:313-8. [PMID: 15112324 DOI: 10.1002/mrd.20083] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In the present study, we examined the developmental ability of enucleated zygotes, MII oocytes, and parthenogenetically activated oocytes at pronuclear stages (parthenogenetic PNs) as recipient cytoplasm for rat embryonic cell nuclear transfer. Enucleated zygotes as recipient cytoplasm receiving two-cell nuclei allowed development to blastocysts, whereas the development of embryos reconstituted with MII oocytes and parthenogenetic PNs was arrested at the two-cell stage. Previous observations in rat two-cell embryos suggested that the distribution of microtubules is involved in two-cell arrest. Therefore, we also examined the distribution of microtubules using immunofluorescence. At the two-cell stage after nuclear transfer into enucleated zygotes, microtubules were distributed homogeneously in the cytoplasm during interphase, and normal mitotic spindles were observed in cleaving embryos from the two- to four-cell stage. In contrast, embryos reconstituted with MII oocytes and parthenogenetic PNs showed aberrant microtubule organization. In enucleated zygotes, fibrous microtubules were distributed homogeneously in the cytoplasm. In contrast, dense microtubules were localized at the subcortical area in the cytoplasm and strong immunofluorescence intensity was observed at the plasma membrane, while very weak intensity was detected in the central part of enucleated MII oocytes. In enucleated parthenogenetic PNs, high-density and fibrous microtubules were distributed in the subcortical and central areas, respectively. Pre-enucleated parthenogenetic PNs also showed lower intensity of microtubule immunofluorescence in the central cytoplasm than zygotes. In conclusion, the results of the present study showed that zygote cytoplasm is better as recipient than MII oocyte and parthenogenetic PNs for rat two-cell embryonic cell nuclear transfer to develop beyond four-cell stage. Furthermore, microtubule organization is involved in the development of reconstituted embryos to overcome the two-cell arrest.
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Affiliation(s)
- Tadahiro Shinozawa
- Laboratory of Animal Reproduction, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan.
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Popova E, Krivokharchenko A, Ganten D, Bader M. Efficiency of transgenic rat production is independent of transgene-construct and overnight embryo culture. Theriogenology 2004; 61:1441-53. [PMID: 15036975 DOI: 10.1016/j.theriogenology.2003.08.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2003] [Revised: 07/04/2003] [Accepted: 08/10/2003] [Indexed: 11/25/2022]
Abstract
The aim of the present work was to study factors affecting the efficiency of transgenic technology in rats. We investigated the possible effects of pronuclear microinjection of buffer or different DNA-constructs on survival and development of rat zygotes in vitro and in vivo as well as the influence of overnight culture of these embryos before transfer into pseudopregnant foster mothers. The survival rate of zygotes and their development to the two-cell and morula stage was not affected by pronuclear microinjection with different DNA-constructs or buffer. However, the development to the blastocyst stage was impaired. Nevertheless, there was no difference in blastocyst development between zygotes injected with DNA-constructs or with buffer. Neither was there a difference in cell number in in vitro cultured blastocysts resulting from pronuclear microinjection of a transgene compared with non-injected controls. The survival rate to term was about 30% irrespective of whether microinjected embryos were transferred immediately after microinjection or after overnight culture in vitro. However, a reduction in the survival to term was observed for non-injected zygotes when they were developed in vitro to the two-cell stage before transfer to a pseudopregnant female. The percentage of transgenic rats that resulted from microinjected zygotes was similar in all groups regardless of the DNA-construct used (2.7-10.0%). In conclusion, the main detrimental factor in the microinjection of rat zygotes is the introduction of solution in the pronucleus. Overnight culture of zygotes between microinjection and oviduct transfer does not decrease the efficiency of transgenic rat generation.
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Affiliation(s)
- Elena Popova
- Max-Delbrück Center for Molecular Medicine (MDC), Robert-Rössle-Str. 10, Berlin-Buch D-13092, Germany
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Matsumoto H, Jiang JY, Mitani D, Sato E. Distribution and gene expression of cytoskeletal proteins in two-cell rat embryos and developmental arrest. THE JOURNAL OF EXPERIMENTAL ZOOLOGY 2002; 293:641-8. [PMID: 12410592 DOI: 10.1002/jez.10179] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Previous observations in rat two-cell embryos suggested that distribution of microfilaments and microtubules are involved in developmental arrest. Therefore, we examined the distribution of cytoskeletal proteins, actin binding proteins, and microtubule-associated proteins in rat two-cell embryos. We also examined gene expression of beta-actin, alpha-tubulin, and cytoskeletal proteins that showed changes in their distributions. Distribution of cytoskeletal proteins was examined by immunocytochemistry. Although distributions of alpha-actinin, MAP1A, MAP1B/MAP5, and MAP2 were disturbed in arrested embryos, these abnormal distributions occurred following the initiations of developmental arrest and marked damage of microfilaments and microtubules. Gene expression of cytoskeletal proteins was examined by RT-PCR. Beta-actin and alpha-actinin mRNA was detected in normal late two-cell stage but not in arrested embryos. The difference occurred after zygotic gene activation. Expression of alpha-tubulin was detected in neither normal late two-cell stage nor arrested embryos. No MAP1A, MAP1B/MAP5, or MAP2 expression was detected in embryos during the two-cell stage. In conclusion, both distributions of microfilaments and microtubules are closely involved in rat developmental arrest, but other distributions of cytoskeletal proteins, actin binding proteins, and microtubule-associated proteins do not appear to have major roles in two-cell arrest. Furthermore, mRNA expression patterns are different between microfilaments and microtubules. Both distribution and mRNA transcription of microfilaments are involved in rat developmental arrest, whereas only distribution of maternal microtubules is disturbed in arrested embryos.
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Affiliation(s)
- Hiromichi Matsumoto
- Laboratory of Animal Reproduction, Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555, Japan.
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Krivokharchenko A, Galat V, Ganten D, Bader M. In vitro formation of tetraploid rat blastocysts after fusion of two-cell embryos. Mol Reprod Dev 2002; 61:460-5. [PMID: 11891917 DOI: 10.1002/mrd.90001] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Gene targeting technology is not available in the rat which is an animal model of major importance, e.g., in cardiovascular research. This is due to the fact that the rat embryonic stem cell (ESC)-like cells established by several groups do not form germ-line chimeras when injected into blastocysts. In the mouse, the aggregation of ESC with tetraploid embryos has allowed the generation of animals completely derived from these cells. However, aggregation of rat ESC-like cells with tetraploid rat embryos has not yet been attempted to evaluate their developmental capacity. Therefore, we established a method to produce tetraploid rat embryos by fusion at the two-cell stage. Chemical fusion by polyethylene glycol (PEG) was shown to be less efficient (56.3% fused embryos) than electrofusion (96.1% fused embryos). The rate of development of fused embryos to blastocysts was independent of the fusion method and similar to the rate of control embryos. However, this rate was lower when the embryos had been cultured from the zygote state before fusion (14-20%) compared to freshly isolated two-cell embryos (41-63%). Alike for the mouse, blastocysts derived from fused two-cell rat embryos contained about half the number of cells as control blastocysts and were homogeneously tetraploid with no evidence of mosaicism. This method may be useful for the establishment of gene-targeting technology in the rat.
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Josefsberg LB, Kaufman O, Galiani D, Kovo M, Dekel N. Inactivation of M-phase promoting factor at exit from first embryonic mitosis in the rat is independent of cyclin B1 degradation. Biol Reprod 2001; 64:871-8. [PMID: 11207203 DOI: 10.1095/biolreprod64.3.871] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Exit from M-phase and completion of cell division requires inactivation of M-phase promoting factor (MPF), a heterodimer composed of the regulatory cyclin B1 and the catalytic p34cdc2 kinase. Inactivation of MPF is associated with cyclin B1 degradation that is brought about by the ubiquitin-proteasome pathway. Our study examined the role of the proteasome in the first mitosis of rat embryos and its participation in the regulation of cyclin B1 degradation and MPF inactivation. We show that in the early zygote the proteasome is evenly distributed in the ooplasm and the nucleus, whereas during mitosis it accumulates on the spindle apparatus. We further demonstrate that inhibition of proteasomal catalytic activity prevents 1-cell embryos from undergoing mitosis. This mitotic arrest is associated with the presence of relatively high amounts of cyclin B1, which unexpectedly does not result in elevated MPF activity. Our findings strongly imply that completion of the first embryonic division depends on proteasomal degradation and that cyclin B1 is included among its target proteins. They also provide the first evidence that MPF inactivation at this stage of development is not solely dependent upon cyclin B1 degradation and is insufficient to allow the formation of the 2-cell embryo.
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Affiliation(s)
- L B Josefsberg
- Department of Biological Regulation, The Weizmann Institute of Science, Rehovot, 76100 Israel Faculty of Life Science, Bar-Ilan University, Ramat-Gan, Israel
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