The microenvironment created by non-blocking embryos in aggregates may rescue blocking embryos via cell–embryo adherent contacts

Sekirina, Galina G.; Neganova, Irina

doi:10.1017/s0967199400002744

Cited by 12 publications

(5 citation statements)

References 49 publications

(51 reference statements)

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“…These results may be explained by structural reorganisation of cells with respect to different phases of cell cycle, which is especially dramatic when one or both sister blastomeres are ready to divide. It is shown that intact and isolated sister blastomeres of normal 2-cell embryos as well as of embryos rescued from the '2-cell block' can asynchronously enter M-phase of the cell cycle (Kelly et al, 1978;Lehtonen, 1980;Dyban & Sekirina, 1981;Sekirina & Neganova, 1995). In the present study we have found that the sister blastomeres of tetraploid embryos reconstructed by fusion can also enter mitosis asynchronously.…”

Section: Discussionsupporting

confidence: 60%

The behaviour of mitochondria and cell integration during somatic hybridisation of sister blastomeres of the 2-cell mouse embryo

Sekirina

Bogoliubova

Antonova

et al. 1997

Zygote

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The capacity of sister blastomeres of mouse embryos for induced fusion changed during the 2-cell stage. It was at low level (24%) at the early 2-cell stage, increased and reached 98.5% at the middle 2-cell stage and fell sharply to 31% at the late 2-cell stage. At the time corresponding to the G 2 /Mphase of the cell cycle the blastomeres fused in only 8% of cases. Vital staining of 2-cell embryos by rhodamine 123 showed that the mitochondria were dispersed throughout the cytoplasm with a ringlike (around the nucleus) or spot-like (over the metaphase plate) concentration in the centre of each blastomere. At the periphery of blastomeres the mitochondrial content was low. The behaviour of the mitochondria reflected the subsequent events of structural and functional integration of the sister blastomeres under induced fusion: a discernible boundary between partners during 30min after electrofusion or 1 h after fusion with polyethylene glycol; movement of the two 'rings' to the centre of the blastomere fusion products (BFP) to form one large bright 'spot' over the common metaphase plate; mitochondria outlining the shape of the spindle and connection between sister blastomeres until completion of the first mitosis of BFP. The data obtained suggest that fusion of the blastomeres does not lead to extensive changes in the hybrid cytoplasm and integration of nuclear material is taking place only at metaphase stage. Cytogenetic examination of BFP at the 2-cell stage confirmed reconstruction of the tetraploid embryos and found that sister blastomeres of such embryos could asynchronously enter the next cleavage division similarly to normal diploid 2-cell embryos.

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Section: Discussionsupporting

confidence: 60%

The behaviour of mitochondria and cell integration during somatic hybridisation of sister blastomeres of the 2-cell mouse embryo

Sekirina

Bogoliubova

Antonova

et al. 1997

Zygote

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“…In contrast to the mouse data, a recent report in bovine showed no improvement in the development rate of NT aggregates or OCT4 levels when compared to non-aggregates, although the cell number in aggregates was increased (Misica-Turner et al, 2006). This apparent discrepancy and early studies (Sekirina and Neganova, 1995;Neganova et al, 1998) suggest that beneficial complementation between aggregated cells may be regulated by the timing of the aggregation. Mouse NT aggregation was performed after the onset of major embryonic genome activation, while up to now all the bovine NT aggregations have been conducted before genome activation.…”

Section: Discussionmentioning

confidence: 64%

Global gene expression analysis of bovine blastocysts produced by multiple methods

Zhou¹,

Xiang²,

Walker³

et al. 2007

Molecular Reproduction Devel

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Reproductive efficiency using somatic cell nuclear transfer (SCNT) technology remains suboptimal. Of the various efforts to improve the efficiency, chromatin transfer (CT) and clone-clone aggregation (NTagg) have been reported to produce live cloned animals. To better understand the molecular mechanisms of somatic cell reprogramming during SCNT and assess the various SCNT methods on the molecular level, we performed gene expression analysis on bovine blastocysts produced via standard nuclear transfer (NT), CT, NTagg, in vitro fertilization (IVF), and artificial insemination (AI), as well as on somatic donor cells, using bovine genome arrays. The expression profiles of SCNT (NT, CT, NTagg) embryos were compared with IVF and AI embryos as well as donor cells. NT and CT embryos have indistinguishable gene expression patterns. In comparison to IVF or AI embryos, the number of differentially expressed genes in NTagg embryos is significantly higher than in NT and CT embryos. Genes that were differentially expressed between all the SCNT embryos and IVF or AI embryos are identified. Compared to AI embryos, more than half of the genes found deregulated between SCNT and AI embryos appear to be the result of in vitro culture alone. The results indicate that although SCNT methods have altered differentiated somatic nuclei gene expression to more closely resemble that of embryonic nuclei, combination of insufficient reprogramming and in vitro culture condition compromise the developmental potential of SCNT embryos. This is the first set of comprehensive data for analyzing the molecular impact of various nuclear transfer methods on bovine pre-implantation embryos.

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“…On the other hand, but not exclusively, results from the second experiment suggest that damage caused due to the exposure to high-osmolarity media for a limited time in the MBT stage can be compensated and/or repaired later either by cell functional replacement (Sekirina and Neganova, 1995;Boiani et al, 2003) or by maternal effects. The existence of these compensating mechanisms would also explain the observed delay in developmental timing.…”

Section: Discussionmentioning

confidence: 91%

Osmolarity and composition of cell culture media affect further development and survival in zebrafish embryos

Pérez-Camps

García-Ximénez

2008

Animal

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With the aim of carrying out chimaerism and somatic cell-midblastula transition (MBT) embryos co-culture experiments in freshwater fish species, we evaluated the effect of osmolarity and composition of two media commonly used in cell fish culture on MBT zebrafish embryos and their further development and survival. To this end, wild zebrafish dechorionated embryos in midblastula stage were cultured for 6 days (Experiment 1: 189 embryos) or 1 h (Experiment 2: 150 embryos) in three different media: Hanks' 10% (H-10), 35 mOsm; Hanks' 100% (CH), 315 mOsm; and L-15 with serum (L-15: 315 mOsm). High osmolarity affected the survival rate (6 days: L-15: 45.1% v. CH: 72.34% v. H-10: 100%, P , 0.05; after 6 days: 0% both in L-15 and CH) and slowed their developmental timing. Embryos showed tail deformation (curly) as well as body paralysis at 48 h when they showed tail movements at 28 h. Differences in tail deformation were observed between high-osmolarity groups (CH: 85.10% v. L-15: 98.04%; P , 0.05). In Experiment 2, no effects on survival rate were observed. Teratogenic effects were only observed in L-15 (L-15: 12.98% v. CH: 0%; P , 0.05). Loss of motility was not detected in any group at 48 h. Optimum osmolar condition for cultured cells and also embryonic cells is around 315 mOsm and so, during chimaerism experiments (usually practised at MBT stage), present results indicate that midblastula embryos can acceptably bear the effects caused by 315 mOsm (CH) for 1 h, even though this involves a certain delay in developmental timing.

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The microenvironment created by non-blocking embryos in aggregates may rescue blocking embryos via cell–embryo adherent contacts

Cited by 12 publications

References 49 publications

The behaviour of mitochondria and cell integration during somatic hybridisation of sister blastomeres of the 2-cell mouse embryo

The behaviour of mitochondria and cell integration during somatic hybridisation of sister blastomeres of the 2-cell mouse embryo

Global gene expression analysis of bovine blastocysts produced by multiple methods

Osmolarity and composition of cell culture media affect further development and survival in zebrafish embryos

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