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Uncoupled embryonic and extra-embryonic tissues compromise blastocyst development after somatic cell nuclear transfer.

Degrelle SA, Jaffrezic F, Campion E, Lê Cao KA, Le Bourhis D, Richard C, Rodde N, Fleurot R, Everts RE, Lecardonnel J, Heyman Y, Vignon X, Yang X, Tian XC, Lewin HA, Renard JP, Hue I - PLoS ONE (2012)

Bottom Line: SCNT was also associated with a high incidence of discordance in embryonic and extra-embryonic patterns, as evidenced by morphological and molecular "uncoupling".Elongation appeared to be secondarily affected; only 3 of 30 conceptuses had abnormally elongated shapes and there were very few differences in gene expression when they were compared to the controls.When taking into account SCNT conceptus somatic origin, i.e. the reprogramming efficiency of each bovine ear fibroblast (Low: 0029, Med: 7711, High: 5538), we found that embryonic abnormalities or severe embryonic/extra-embryonic uncoupling were more tightly correlated to embryo loss at implantation than were elongation defects.

View Article: PubMed Central - PubMed

Affiliation: INRA, UMR 1198 Biologie du Développement et Reproduction, Jouy-en-Josas, France.

ABSTRACT
Somatic cell nuclear transfer (SCNT) is the most efficient cell reprogramming technique available, especially when working with bovine species. Although SCNT blastocysts performed equally well or better than controls in the weeks following embryo transfer at Day 7, elongation and gastrulation defects were observed prior to implantation. To understand the developmental implications of embryonic/extra-embryonic interactions, the morphological and molecular features of elongating and gastrulating tissues were analysed. At Day 18, 30 SCNT conceptuses were compared to 20 controls (AI and IVP: 10 conceptuses each); one-half of the SCNT conceptuses appeared normal while the other half showed signs of atypical elongation and gastrulation. SCNT was also associated with a high incidence of discordance in embryonic and extra-embryonic patterns, as evidenced by morphological and molecular "uncoupling". Elongation appeared to be secondarily affected; only 3 of 30 conceptuses had abnormally elongated shapes and there were very few differences in gene expression when they were compared to the controls. However, some of these differences could be linked to defects in microvilli formation or extracellular matrix composition and could thus impact extra-embryonic functions. In contrast to elongation, gastrulation stages included embryonic defects that likely affected the hypoblast, the epiblast, or the early stages of their differentiation. When taking into account SCNT conceptus somatic origin, i.e. the reprogramming efficiency of each bovine ear fibroblast (Low: 0029, Med: 7711, High: 5538), we found that embryonic abnormalities or severe embryonic/extra-embryonic uncoupling were more tightly correlated to embryo loss at implantation than were elongation defects. Alternatively, extra-embryonic differences between SCNT and control conceptuses at Day 18 were related to molecular plasticity (high efficiency/high plasticity) and subsequent pregnancy loss. Finally, because it alters re-differentiation processes in vivo, SCNT reprogramming highlights temporally and spatially restricted interactions among cells and tissues in a unique way.

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Molecular uncoupling of E and EE tissues in SCNT conceptuses.The gene set used to classify each conceptus includes six genes from the extra-embryonic tissues and has been described as an accurate predictor of embryonic stages in controls. A) Patterns resulting from AI: examples of a filamentous conceptus with a disc at stage 3 (Fil-N2) and a trophoblastic vesicle (TV) with an ablated disc since Day 15. B) Patterns resulting from SCNT: examples of tubular conceptuses with a delayed embryonic disc (stage 2) or no disc (Ab2).
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pone-0038309-g005: Molecular uncoupling of E and EE tissues in SCNT conceptuses.The gene set used to classify each conceptus includes six genes from the extra-embryonic tissues and has been described as an accurate predictor of embryonic stages in controls. A) Patterns resulting from AI: examples of a filamentous conceptus with a disc at stage 3 (Fil-N2) and a trophoblastic vesicle (TV) with an ablated disc since Day 15. B) Patterns resulting from SCNT: examples of tubular conceptuses with a delayed embryonic disc (stage 2) or no disc (Ab2).

Mentions: To build on these discordance data obtained from macroscopic observations, we used a small extra-embryonic gene set that was previously identified as an accurate predictor of the embryonic stages in controls at gastrulation (AI [24]). When elongation and gastrulation were delayed, the extra-embryonic gene set displayed similar patterns in the SCNT and AI groups despite them being in different embryonic stages (Tub-D versus Fil-N2 phenotypes; Fig. 5). In addition, with or without embryonic tissues, tubular SCNT conceptuses were similar. There was thus a discrepancy between the molecular and morphological results, which highlighted another important difference. Despite having a morphology similar to trophoblastic vesicles (TV), SCNTs without discs did not display the extra-embryonic pattern of TVs, but that of tubular SCNTs, irrespective of their embryonic stage (delayed or normal).


Uncoupled embryonic and extra-embryonic tissues compromise blastocyst development after somatic cell nuclear transfer.

Degrelle SA, Jaffrezic F, Campion E, Lê Cao KA, Le Bourhis D, Richard C, Rodde N, Fleurot R, Everts RE, Lecardonnel J, Heyman Y, Vignon X, Yang X, Tian XC, Lewin HA, Renard JP, Hue I - PLoS ONE (2012)

Molecular uncoupling of E and EE tissues in SCNT conceptuses.The gene set used to classify each conceptus includes six genes from the extra-embryonic tissues and has been described as an accurate predictor of embryonic stages in controls. A) Patterns resulting from AI: examples of a filamentous conceptus with a disc at stage 3 (Fil-N2) and a trophoblastic vesicle (TV) with an ablated disc since Day 15. B) Patterns resulting from SCNT: examples of tubular conceptuses with a delayed embryonic disc (stage 2) or no disc (Ab2).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3368877&req=5

pone-0038309-g005: Molecular uncoupling of E and EE tissues in SCNT conceptuses.The gene set used to classify each conceptus includes six genes from the extra-embryonic tissues and has been described as an accurate predictor of embryonic stages in controls. A) Patterns resulting from AI: examples of a filamentous conceptus with a disc at stage 3 (Fil-N2) and a trophoblastic vesicle (TV) with an ablated disc since Day 15. B) Patterns resulting from SCNT: examples of tubular conceptuses with a delayed embryonic disc (stage 2) or no disc (Ab2).
Mentions: To build on these discordance data obtained from macroscopic observations, we used a small extra-embryonic gene set that was previously identified as an accurate predictor of the embryonic stages in controls at gastrulation (AI [24]). When elongation and gastrulation were delayed, the extra-embryonic gene set displayed similar patterns in the SCNT and AI groups despite them being in different embryonic stages (Tub-D versus Fil-N2 phenotypes; Fig. 5). In addition, with or without embryonic tissues, tubular SCNT conceptuses were similar. There was thus a discrepancy between the molecular and morphological results, which highlighted another important difference. Despite having a morphology similar to trophoblastic vesicles (TV), SCNTs without discs did not display the extra-embryonic pattern of TVs, but that of tubular SCNTs, irrespective of their embryonic stage (delayed or normal).

Bottom Line: SCNT was also associated with a high incidence of discordance in embryonic and extra-embryonic patterns, as evidenced by morphological and molecular "uncoupling".Elongation appeared to be secondarily affected; only 3 of 30 conceptuses had abnormally elongated shapes and there were very few differences in gene expression when they were compared to the controls.When taking into account SCNT conceptus somatic origin, i.e. the reprogramming efficiency of each bovine ear fibroblast (Low: 0029, Med: 7711, High: 5538), we found that embryonic abnormalities or severe embryonic/extra-embryonic uncoupling were more tightly correlated to embryo loss at implantation than were elongation defects.

View Article: PubMed Central - PubMed

Affiliation: INRA, UMR 1198 Biologie du Développement et Reproduction, Jouy-en-Josas, France.

ABSTRACT
Somatic cell nuclear transfer (SCNT) is the most efficient cell reprogramming technique available, especially when working with bovine species. Although SCNT blastocysts performed equally well or better than controls in the weeks following embryo transfer at Day 7, elongation and gastrulation defects were observed prior to implantation. To understand the developmental implications of embryonic/extra-embryonic interactions, the morphological and molecular features of elongating and gastrulating tissues were analysed. At Day 18, 30 SCNT conceptuses were compared to 20 controls (AI and IVP: 10 conceptuses each); one-half of the SCNT conceptuses appeared normal while the other half showed signs of atypical elongation and gastrulation. SCNT was also associated with a high incidence of discordance in embryonic and extra-embryonic patterns, as evidenced by morphological and molecular "uncoupling". Elongation appeared to be secondarily affected; only 3 of 30 conceptuses had abnormally elongated shapes and there were very few differences in gene expression when they were compared to the controls. However, some of these differences could be linked to defects in microvilli formation or extracellular matrix composition and could thus impact extra-embryonic functions. In contrast to elongation, gastrulation stages included embryonic defects that likely affected the hypoblast, the epiblast, or the early stages of their differentiation. When taking into account SCNT conceptus somatic origin, i.e. the reprogramming efficiency of each bovine ear fibroblast (Low: 0029, Med: 7711, High: 5538), we found that embryonic abnormalities or severe embryonic/extra-embryonic uncoupling were more tightly correlated to embryo loss at implantation than were elongation defects. Alternatively, extra-embryonic differences between SCNT and control conceptuses at Day 18 were related to molecular plasticity (high efficiency/high plasticity) and subsequent pregnancy loss. Finally, because it alters re-differentiation processes in vivo, SCNT reprogramming highlights temporally and spatially restricted interactions among cells and tissues in a unique way.

Show MeSH
Related in: MedlinePlus