Abstract
Purpose
Normally fertilized zygotes generally show two pronuclei (2PN) and the extrusion of the second polar body. Conventional in vitro fertilization (c-IVF) and intracytoplasmic sperm injection (ICSI) often result in abnormal monopronuclear (1PN), tripronuclear (3PN), or other polypronuclear zygotes. In this study, we performed combined analyses of the methylation status of pronuclei (PN) and the number of centrosomes, to reveal the abnormal fertilization status in human zygotes.
Method
We used differences in DNA methylation status (5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC)) to discriminate between male and female PN in human zygotes. These results were also used to analyze the centrosome number to indicate how many sperm entered into the oocyte.
Result
Immunofluorescent analysis shows that all of the normal 2PN zygotes had one 5mC/5hmC double-positive PN and one 5mC-positive PN, whereas a parthenogenetically activated oocyte had only 5mC staining of the PN. All of the zygotes derived from ICSI (1PN, 3PN) had two centrosomes as did all of the 2PN zygotes derived from c-IVF. Of the 1PN zygotes derived from c-IVF, more than 50 % had staining for both 5mC and 5hmC in a single PN, and one or two centrosomes, indicating fertilization by a single sperm. Meanwhile, most of 3PN zygotes derived from c-IVF had a 5mC-positive PN and two 5mC/5hmC double-positive PNs, and had four or five centrosomes, suggesting polyspermy.
Conclusions
We have established a reliable method to identify the PN origin based on the epigenetic status of the genome and have complemented these results by counting the centrosomes of zygotes.



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Abbreviations
- 5mC:
-
5-Methylcytosine
- 5hmC:
-
5-Hydroxymethylcytosine
- ART:
-
Assisted reproductive technologies
- BSA:
-
Bovine serum albumin
- PBS:
-
Phosphate-buffered saline
- PN:
-
Pronucleus (plural: pronuclei)/pronuclear
- mPN:
-
Male pronuclei
- fPN:
-
Female pronuclei
- 2nd PB:
-
Second polar body
- c-IVF:
-
Conventional in vitro fertilization
- ICSI:
-
Intracytoplasmic sperm injection
- MII:
-
Metaphase II
References
Kola I, Trounson A, Dawson G, Rogers P. Tripronuclear human oocytes: altered cleavage patterns and subsequent karyotypic analysis of embryos. Biol Reprod. 1987;37:395–401.
Staessen C, Janssenwillen C, Devroey P, Van Steirteghem AC. Cytogenetic and morphological observations of single pronucleated human oocytes after in-vitro fertilization. Hum Reprod. 1993;8:221–23.
Taylor AS, Braude PR. The early development and DNA content of activated human oocytes and parthenogenetic human embryos. Hum Reprod. 1994;9:2389–97.
Palermo GD, Munné S, Colombero LT, Cohen J, Rosenwaks Z. Genetics of abnormal human fertilization. Hum Reprod. 1995;1:120–7.
Balakier H, Cadesky K. The frequency and developmental capability of human embryos containing multinucleated blastomeres. Hum Reprod. 1997;12:800–4.
Rosenbusch B, Schneider M, Kreienberg R, Brucker C. Cytogenetic analysis of human zygotes displaying three pronuclei and one polar body after intracytoplasmic sperm injection. Hum Reprod. 2001;16:2362–7.
Mio Y, Iwata K, Yumoto K, Maeda K. Human embryonic behavior observed with time-lapse cinematography. J Health Med Inf. 2014;5:143.
Mio Y. Morphological analysis of human embryonic development using time-lapse cinematography. J Mamm Ova Res. 2006;23:27–35.
Iqbal K, Jin SG, Pfeifer GP, Szabó PE. Reprogramming of the paternal genome upon fertilization involves genome-wide oxidation of 5-methylcytosine. Proc Natl Acad Sci U S A. 2011;108:3642–7.
Wossidlo M, Nakamura T, Lepikhov K, Marques CJ, Zakhartchenko V, Boiani M, et al. 5-Hydroxymethylcytosine in the mammalian zygote is linked with epigenetic reprogramming. Nat Commun. 2011;2:241.
Gu TP, Guo F, Yang H, Wu HP, Xu GF, Liu W, et al. The role of Tet3 DNA dioxygenase in epigenetic reprogramming by oocytes. Nature. 2011;477:606–10.
Sathananthan AH, Kola I, Osborne J, Trouson A, Ng SC, Bongso A, et al. Centrioles in the beginning of human development. Proc Natl Acad Sci USA. 1991;88:4806–10.
Sathananthan AH, Ratnam SS, Ng SC, Tarín JJ, Gianaroli L, Trouson A. The sperm centriole: its inheritance, replication and perpetuation in early human embryos. Hum Reprod. 1996;11:345–56.
Munné S, Cohen J. Chromosome abnormalities in human embryos. Hum Reprod Update. 1998;4:842–55.
Plachot M. Chromosome analysis of oocytes and embryos. In Verlinsky Y, Kuliev A. (eds), Preimplantation Genetics. Plenum Press; New York, 1991: 103–12.
Palermo GD, Munné S, Cohen J. The human zygote inherits its mitotic potential from the male gamete. Hum Reprod. 1994;9:1220–5.
Levron J, Munné S, Willadsen S, Rosenwaks Z, Cohen J. Male and female genomes associated in a single pronucleus in human zygotes. Biol Reprod. 1995;52:653–7.
Staessen C, Van Steirteghem AC. The chromosomal constitution of embryos developing from abnormally fertilized oocytes after intracytoplasmic sperm injection and conventional in-vitro fertilization. Hum Reprod. 1997;12:321–7.
Mio Y, Maeda K. Time-lapse cinematography of dynamic changes occurring during in vitro development of human embryos. Am J Obstet Gynecol. 2008;199:1–5.
Mio Y, Iwata K, Yumoto K, Kai Y, Sargant HC, Mizoguchi C, et al. Possible mechanism of polyspermy block in human oocytes observed by time-lapse cinematography. J Assist Reprod Genet. 2012;29:951–6.
Iwata K, Yumoto K, Sugishima M, Mizoguchi C, Kai Y, Iba Y, et al. Analysis of compaction initiation in human embryos by using time-lapse cinematography. J Assist Reprod Genet. 2014;31:421–6.
Balakier H, Squire J, Casper RF. Characterization of abnormal one pronuclear human oocytes by morphology, cytogenetics and in-situ hybridization. Hum Reprod. 1993;8:402–8.
Nagy ZP, Liu J, Joris H, Devroey P, Van Steirteghem A. Time-course of oocyte activation, pronucleus formation and cleavage in human oocytes fertilized by intracytoplasmic sperm injection. Hum Reprod. 1994;9:1743–8.
Payne D, Flaherty SP, Barry MF, Matthews CD. Preliminary observations on polar body extrusion and pronuclear formation in human oocytes using time-lapse video cinematography. Hum Reprod. 1997;12:532–41.
Plachot M, Mandelbaum J, Junca AM, De Grouchy J, Salta-Baroux J, Cohen J. Cytogenetic analysis and development capacity of normal and abnormal embryos after IVF. Hum Reprod. 1989;4:99–103.
Parelmo G, Joris H, Derde MP, Camus M, Devroey P, Van Steirteghem A. Sperm characteristics and outcome of human assisted fertilization by subzonal insemination and intracytoplasmic sperm injection. Fertil Steril. 1993;59:826–35.
Grossman M, Calafell JM, Brandy N, Vanrell JA, Rubio C, Pellicer A, et al. Origin of tripronucleate zygotes after intracytoplasmic sperm injection. Hum Reprod. 1997;12:2762–5.
Rosenbusch B, Schneider M, Kreienberg R, Brucker C. Cytogenetic analysis of giant oocytes and zygotes to assess their relevance for the development of digynic triploidy. Hum Reprod. 2002;17:2388–93.
Mayer W, Niveleau A, Walter J, Fundele R, Haaf T. Demethylation of the zygotic paternal genome. Nature. 2000;403:501–2.
Santos F, Hendrich B, Reik W, Dean W. Dynamic reprogramming of DNA methylation in the early mouse embryo. Dev Biol. 2002;241:172–82.
Beaujean N, Harttshorne G, Cavilla J, Taylor J, Gardner J, Wilmut I, et al. Non-conservation of mammalian preimplantation methylation dynamics. Curr Biol. 2004;14:266–7.
Xu Y, Zhang JJ, Grifo JA, Krey LC. DNA methylation patterns in human tripronucleate zygotes. Mol Hum Reprod. 2005;11:167–71.
Nakamura T, Arai Y, Umehara H, Masuhara M, Kimura T, Taniguchi H, et al. PGC7/Stella protects against DNA demethylation in early embryogenesis. Nat Cell Biol. 2007;9:64–71.
Guo H, Zhu P, Yan L, Li R, Hu B, Lian Y, et al. The DNA methylation landscape of human early embryos. Nature. 2014;511:606–10.
Zhao XM, Du WH, Hao HS, Wang D, Qin T, Liu Y, et al. Effect of vitrification on promoter methylation and the expression of pluripotency and differentiation genes in mouse blastocysts. Mol Reprod Dev. 2012;79:445–50.
De Munck N, Petrussa L, Verheyen G, Staessen C, Vandeskelde Y, Sterckx J, et al. Chromosomal meiotic segregation, embryonic developmental kinetics and DNA (hydroxy)methylation analysis consolidate the safety of human oocyte vitrification. Mol Hum Reprod. 2015;21:535–44.
Otsu E, Sato A, Nagaki M, Araki Y, Utsunomiya T. Developmental potential and chromosomal constitution of embryos derived from larger single pronuclei of human zygotes used in in vitro fertilization. Fertil Steril. 2004;81:723–4.
Acknowledgments
We are grateful to Keitaro Yumoto, Minako Sugishima, Chizuru Mizoguchi, Sayako Furuyama, and Yuka Matoba for the collection of the samples. This work was supported by all the staff in the Reproductive Centre, Mio Fertility Clinic, Japan. We also thank S.N. for the technical advice and are particularly grateful for the assistance given by Motokazu Tsuneto.
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Heading
Identifying the fertilization status in abnormal human zygotes
Capsule
A novel method was established to identify PN origin based on the epigenetic status of the genome utilizing a molecular biological technique. The results were also used to analyze the centrosome numbers in human zygotes.
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Supplementary Movie 1
3D image reconstruction of a 2PN zygote derived from c-IVF. Red signal means 5mC-positive and green signal means 5hmC-positive. It provides images relating to Fig. 1a. This normal 2PN zygote showed a 5mC/5hmC double-positive PN and a 5mC-positive PN. (MOV 847 kb)
Supplementary Movie 2
3D image reconstruction of a 1PN zygote derived from c-IVF. It provides images relating to Fig. 1c. This 1PN zygote showed both 5mC and 5hmC staining in a single PN. (MOV 1074 kb)
Supplementary Movie 3
3D image reconstruction of a 3PN zygote derived from c-IVF. It provides images relating to Fig. 1d. This 3PN zygote showed a single 5mC-positive PN and two 5mC/5hmC double-positive PNs. (MOV 856 kb)
Supplementary Movie 4
3D image reconstruction of a 3PN zygote derived from ICSI. It provides images relating to Fig. 1e. This 3PN zygote showed two 5mC-positive PNs and a 5mC/5hmC double-positive PN. (MOV 849 kb)
Supplementary Movie 5
3D image reconstruction of a 3PN zygote derived from c-IVF at syngamy. It provides images relating to Fig. 2g. This movie shows a Y-shaped metaphase plate and aberrant centrosome positions of this 3PN zygote. (MOV 288 kb)
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Kai, Y., Iwata, K., Iba, Y. et al. Diagnosis of abnormal human fertilization status based on pronuclear origin and/or centrosome number. J Assist Reprod Genet 32, 1589–1595 (2015). https://doi.org/10.1007/s10815-015-0568-1
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DOI: https://doi.org/10.1007/s10815-015-0568-1