Abbreviation of the second meiotic division by precocious fertilization in fish oocytes

Isobe, Takashi

doi:10.1002/(sici)1097-010x(19970415)277:6<450::aid-jez5>3.0.co;2-n

Cited by 11 publications

(7 citation statements)

References 20 publications

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“…In contrast, the cell cycles of adult somatic cell nuclei of the same animals are all 24 h or more in length. Therefore, the first cleavage of the recipient cytoplasm occurs before the karyokinetic events of the donor nuclei are complete, which can result in a variety of chromosomal aberrations, including ploidy mosaicism, where cells with abnormal karyotypes are present in the resultant nuclear transplanted animal (Di Berardino & Hoffner 1970;Di Berardino 1979, 1997.…”

Section: Introductionsupporting

confidence: 83%

Diploidized eggs reprogram adult somatic cell nuclei to pluripotency in nuclear transfer in medaka fish (Oryzias latipes)

et al. 2007

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Reprogramming of adult somatic cell nuclei to pluripotency has been unsuccessful in non-mammalian animals, primarily because of chromosomal aberrations in nuclear transplants, which are considered to be caused by asynchrony between the cell cycles of the recipient egg and donor nucleus. In order to normalize the chromosomal status, we used diploidized eggs by retention of second polar body release, instead of enucleated eggs, as recipients in nuclear transfer of primary culture cells from the caudal fin of adult green fluorescent protein gene (GFP) transgenic medaka fish (Oryzias latipes). We found that 2.7% of the reconstructed embryos grew into adults that expressed GFP in various tissues in the same pattern as in the donor fish. Moreover, these fish were diploid, fertile and capable of passing the marker gene to the next generation in Mendelian fashion. We hesitate to call these fish 'clones' because we used non-enucleated eggs as recipients; in effect, they may be chimeras consisting of cells derived from diploid recipient nuclei and donor nuclei. In either case, fish adult somatic cell nuclei were reprogrammed to pluripotency and differentiated into a variety of cell types including germ cells via the use of diploidized recipient eggs.

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Section: Introductionsupporting

confidence: 83%

Diploidized eggs reprogram adult somatic cell nuclei to pluripotency in nuclear transfer in medaka fish (Oryzias latipes)

et al. 2007

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“…Changes in morphology of spindles and chromosomes during meiosis were examined as follows (Iwamatsu, 1997). Ovaries were surgically removed from the fish 3 hr before light onset.…”

Section: Histological Observation and Dna Quantitationmentioning

confidence: 99%

Production of Diploid Eggs through Premeiotic Endomitosis in the Hybrid Medaka between Oryzias latipes and O. curvinotus

et al. 2000

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ABSTRACT-A hybrid medaka between Oryzias latipes and O. curvinotus spawns diploid eggs. We examined the cytological mechanisms of diploid egg formation in this hybrid. Oocytes in the hybrid passed through the first and second meiotic divisions and excluded two polar bodies, associated with reduction of the DNA content in oocytes. Each germinal vesicle in vitellogenic oocytes of the hybrid had 48 chromosomes with bivalent chiasmata, precisely twice the number of chromosomes in normal oocytes. These results suggest that before meiosis the chromosomes are doubled by mitosis without cytokinesis, that is, endomitosis, and that the resulting tetraploid oogonia undergo normal meiosis to produce diploid eggs. Except for a few vitellogenic oocytes that are probably derived from endomitotic oogonia, most oocytes were arrested at the zygotene stage in the hybrid ovary, suggesting the existence of checkpoint control that ensures the pairing of homologous chromosomes at prophase I, a situation differing from that in the male in which the checkpoint is at metaphase I. A sac-like structure was characteristic of the hybrid ovary. Although this structure was observed only in the hybrid, it may be a native component of the medaka ovary but difficult to observe because of its deformed outer structure due to enlargement of the inside oocytes. The present study confirms that this hybrid medaka provides a useful experimental system for investigations into the mechanisms of oogenesis and basic architecture of the ovary, which are difficult to analyze by using normal medaka.

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“…Mature eggs were collected from the ovarian cavity, and were placed in a balanced salt solution for medaka (BSS) (Iwamatsu 1983) at 18°C for up to 5 h until use. Mature eggs of medaka were arrested at the metaphase of the second meiosis (Iwamatsu 1997).…”

Section: Preparation Of Recipient Eggsmentioning

confidence: 99%

“…On fertilization, unfertilized eggs are activated by sperm entry into egg cytoplasm and the second meiosis is extricated from the arrest at the metaphase. Finally, a second polar body is extruded onto the surface of the egg cytoplasm at 7-8 min after sperm entry and the second meiosis is completed (Iwamatsu 1997). In nuclear transfer, recipient eggs are automatically activated by pricking the cytoplasm with a glass microcapillary for transfer.…”

Section: Possible Mechanism Of Euploid Mosaic Formation In Nuclear Trmentioning

confidence: 99%

“…In experiments involving amphibian nuclear transfers using somatic cell nuclei, single nuclear transplants have been demonstrated to consist of cells with different ploidies (Di Berardino 1979, 1997. This ploidy mosaicism is more marked in individuals exhibiting aneuploidy with arrested development during the earlier stages of development than it is in individuals exhibiting only slight abnormalities and euploidy, which remain well developed until the later embryonic stages.…”

Section: Introductionmentioning

confidence: 99%

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Ploidy mosaicism in well‐developed nuclear transplants produced by transfer of adult somatic cell nuclei to nonenucleated eggs of medaka (Oryzias latipes)

et al. 2007

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Chromosomal abnormalities such as ploidy mosaicism have constituted a major obstacle to the successful nuclear transfer of adult somatic cell nuclei in lower vertebrates to date. Euploid mosaicism has been reported previously in well-developed amphibian transplants. Here, we investigated ploidy mosaicisms in welldeveloped transplants of adult somatic cell nuclei in medaka fish (Oryzias latipes). Donor nuclei from primary cultured cells from the adult caudal fin of a transgenic strain carrying the green fluorescent protein gene (GFP) were transferred to recipient nonenucleated eggs of a wild-type strain to produce 662 transplants. While some of the transplants developed beyond the body formation stage and several hatched, all exhibited varying degrees of abnormal morphology, limited growth and subsequent death. Twenty-one transplants, 19 embryos and two larvae, were selected for chromosomal analysis; all were well-developed 6-day-old or later embryonic stages exhibiting slight morphological abnormalities and the same pattern of GFP expression as that of the donor strain. In addition, all exhibited various levels of euploid mosaicism with haploid-diploid, haploid-triploid or haploid-diploid-triploid chromosome sets. No visible chromosomal abnormalities were observed. Thus, euploid mosaicism similar to that observed in amphibians was confirmed in well-developed nuclear transplants of fish.

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Abbreviation of the second meiotic division by precocious fertilization in fish oocytes

Cited by 11 publications

References 20 publications

Diploidized eggs reprogram adult somatic cell nuclei to pluripotency in nuclear transfer in medaka fish (Oryzias latipes)

Diploidized eggs reprogram adult somatic cell nuclei to pluripotency in nuclear transfer in medaka fish (Oryzias latipes)

Production of Diploid Eggs through Premeiotic Endomitosis in the Hybrid Medaka between Oryzias latipes and O. curvinotus

Ploidy mosaicism in well‐developed nuclear transplants produced by transfer of adult somatic cell nuclei to nonenucleated eggs of medaka (Oryzias latipes)

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