New opportunities in animal breeding and production — an introductory remark

Wilmut, Ian; Young, Lorraine; DeSousa, Paul; King, Tim

doi:10.1016/s0378-4320(00)00142-1

Cited by 15 publications

(7 citation statements)

References 27 publications

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“…Moreover, towards the end of the last decade, the production of transgenic offspring in the large domestic species by cloning based on nuclear transfer from cultured embryonic, fetal or even adult somatic cells became a reality (for a review, see Wilmut et al, 2000). The rapid expansion of these biotechnologies has not been without problems, leading to an increased focus on embryo quality and viability.…”

mentioning

confidence: 99%

“…In the case of nuclear transfer, the situation is even more pronounced: only 1-2% of the reconstructed embryos become live offspring (for a review, see Wilmut et al, 2000). With these substantial problems in mind, more emphasis has been devoted to understanding of the cell biological processes that regulate initial embryonic development and on which technological manipulation of the embryo may have detrimental impacts.…”

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confidence: 99%

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Ribosomal RNA gene expression and chromosome aberrations in bovine oocytes and preimplantation embryos

Hyttel¹,

Viuff²,

Fair³

et al. 2001

Reproduction

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breeding programmes in several countries. Moreover, towards the end of the last decade, the production of transgenic offspring in the large domestic species by cloning based on nuclear transfer from cultured embryonic, fetal or even adult somatic cells became a reality (for a review, see Wilmut et al., 2000). The rapid expansion of these biotechnologies has not been without problems, leading to an increased focus on embryo quality and viability. This review focuses on the key features of development of the bovine oocyte and embryo, with comparisons of the developmental characteristics of embryos produced in vivo and in vitro. The oocyte is transcriptionally quiescent in the primordial and primary follicle. In the secondary follicle transcription is initiated in the oocyte and a ribosome-synthesizing nucleolus is established in this cell. Transcription and nucleolar activity are enhanced in the tertiary follicle during oocyte growth. When the oocyte reaches approximately 110 µm in diameter, corresponding to a follicle of about 3 mm in diameter, transcription ceases and the nucleolus is inactivated, forming a dense spherical remnant. During the final phase of follicular dominance this remnant becomes vacuolated and, in conjunction with resumption of meiosis, it disperses. The rRNA genes are apparently re-activated during the four-cell stage, that is, the third cell cycle after fertilization, but a nucleolus is not formed. During the subsequent cell cycle, that is, during the eight-cell stage, ribosome-synthesizing nucleoli are again established. Bovine embryos produced in vitro apparently display the same pattern of nucleolus development as that in embryos developed in vivo. Examination of the ploidy of embryonic cells using fluorescence in situ hybridization has revealed that the production of bovine embryos in vitro is associated with increased chromosome aberrations in the embryos. Blastocysts produced in vitro display a significantly higher rate of mixoploidy, that is, when the embryo consists of both normal diploid and abnormal polyploid cells, than that in embryos developed in vivo. The rate of mixoploidy among embryos produced in vitro increases with increasing developmental stage. Moreover, after fertilization in vitro, initially there is a high rate of 'true' polyploidy, that is, when all cells of the embryos are polyploid. However, the polyploid embryos are eliminated before they cleave beyond the eight-cell stage, the stage at which major activation of the embryonic genome occurs in cattle.

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confidence: 99%

mentioning

confidence: 99%

Ribosomal RNA gene expression and chromosome aberrations in bovine oocytes and preimplantation embryos

Hyttel¹,

Viuff²,

Fair³

et al. 2001

Reproduction

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“…Thus, although thousands of calves have been born from embryos produced in vitro, problems with abortions, increased birth weights, dystocia, and high rates of neonatal mortality have been widely reported [14,16,59]. In the case of nuclear transfer, the situation is even more pronounced with only 1-2% of the reconstructed embryos resulting in offspring [60]. With these substantial problems, further investigations devoted to understanding the cell biological processes that regulate initial embryonic development and on which technological manipulations of the embryo may have detrimental impacts are warranted.…”

Section: Possible Ways To Reduce Eemmentioning

confidence: 99%

Arrest or Survive

Madan

2011

Comprehensive Biotechnology

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“…1997b; Parnpai et al. 1999, 2001) are in progress, but their application in animal selection schemes at present is not practicable because of the low efficiency, in particular, the late and pre‐ and perinatal losses (Wilmut et al. 2000).…”

Section: Related Reproductive Biotechnologymentioning

confidence: 99%

Production of Buffalo (Bubalus bubalis) Embryos in vitro: Premises and Promises

Nandi

Raghu

Ravindranatha

et al. 2002

Reprod Domestic Animals

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Techniques for in vitro production (IVP) of buffalo embryos adopting the procedures developed in cattle have received increasing interest in the recent times. A high oocyte maturation, fertilization and cleavage rate and a low rate of blastocyst yield and calving following transfer of in vitro produced buffalo embryos have been obtained. The efficiency of IVP in buffalo is much lower than that in cattle. Several problems need to be resolved before IVP technology can be used regularly in buffalo breeding. This review attempts to present an overview of the different techniques used in buffalo to produce transferable embryos in vitro, namely in vitro maturation and fertilization of immature oocytes and in vitro development of the resulting cleaved embryos to the blastocyst stage before transfer. The problems associated with IVP, the possible solutions and the new biotechniques linked to IVP are discussed.

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New opportunities in animal breeding and production — an introductory remark

Cited by 15 publications

References 27 publications

Ribosomal RNA gene expression and chromosome aberrations in bovine oocytes and preimplantation embryos

Ribosomal RNA gene expression and chromosome aberrations in bovine oocytes and preimplantation embryos

Arrest or Survive

Production of Buffalo (Bubalus bubalis) Embryos in vitro: Premises and Promises

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