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Nuclear transfer (NT) has potential applications in agriculture and biomedicine, but the technology is hindered by low efficiency. Global gene expression analysis of clones is important for the comprehensive study of nuclear reprogramming. Here, we compared global gene expression profiles of individual bovine NT blastocysts with their somatic donor cells and fertilized control embryos using cDNA microarray technology. The NT embryos' gene expression profiles were drastically different from those of their donor cells and closely resembled those of the naturally fertilized embryos. Our findings demonstrate that the NT embryos have undergone significant nuclear reprogramming by the blastocyst stage; however, problems may occur during redifferentiation for tissue genesis and organogenesis, and small reprogramming errors may be magnified downstream in development. bovine | embryo | microarray nuclear transfer

Therapeutic cloning, whereby somatic cell nuclear transfer (SCNT) is used to generate patient-specific embryonic stem cells (ESCs) from blastocysts cloned by nuclear transfer (ntESCs), holds great promise for the treatment of many human diseases. ntESCs have been derived in mice and cattle, but thus far there are no credible reports of human ntESCs. Here we review the recent literature on nuclear reprogramming by SCNT, including studies of gene expression, DNA methylation, chromatin remodeling, genomic imprinting and X chromosome inactivation. Reprogramming of genes expressed in the inner cell mass, from which ntESCs are derived, seems to be highly efficient. Defects in the extraembryonic lineage are probably the major cause of the low success rate of reproductive cloning but are not expected to affect the derivation of ntESCs. We remain optimistic that human therapeutic cloning is achievable and that the derivation of patient-specific ntESC lines will have great potential for regenerative medicine. [ABSTRACT FROM AUTHOR]

Since the creation of Dolly via somatic cell nuclear transfer (SCNT), more than a dozen species of mammals have been cloned using this technology. One hypothesis for the limited success of cloning via SCNT (1%–5%) is that the clones are likely to be derived from adult stem cells. Support for this hypothesis comes from the findings that the reproductive cloning efficiency for embryonic stem cells is five to ten times higher than that for somatic cells as donors and that cloned pups cannot be produced directly from cloned embryos derived from differentiated B and T cells or neuronal cells. The question remains as to whether SCNT-derived animal clones can be derived from truly differentiated somatic cells. We tested this hypothesis with mouse hematopoietic cells at different differentiation stages: hematopoietic stem cells, progenitor cells and granulocytes. We found that cloning efficiency increases over the differentiation hierarchy, and terminally differentiated postmitotic granulocytes yield cloned pups with the greatest cloning efficiency. [ABSTRACT FROM AUTHOR]

The article discusses the feasibility study of therapeutic cloning in primates as new technique for the treatment of many diseases. According to the author, therapeutic cloning refers to the derivation of embryonic stem cells from embryos derived from somatic cell nuclear transfer known as cloning. Though the assurance of human therapeutic cloning is high, the reprogramming of donor cells remained an obstacle and its application is hard to obtain due to moral concerns.

A response by Yang to a letter to the editor about their article "Differentiated cells are more efficient than adult stem cells for cloning by somatic cell nuclear transfer," is presented.

A ternary solid solution of lead-free Na 1/2 Bi 1/2 TiO 3 -BaTiO 3 and BiGaO 3 (NBT-BT-BG) was prepared using conventional, solid-state synthesis. Compositions were prepared near the morphotropic phase boundary (MPB) of ( 1- x )NBT- x BT, located near x = 0.04 -0.09 , and then systematically substituted with 2-5 mol% BG to investigate the effect of the compositional change on the accompanying properties. Dielectric, ferroelectric (FE), and piezoelectric properties were analyzed and compared for all prepared compositions. The FE to ergodic (ER) relaxor transition temperature ( [Formula: see text]) and the reversible electric field-induced relaxor to FE transition were investigated to determine their effects on the strain response. It was found that the MPB composition of 0.93NBT-0.07BT required the least amount of the tertiary phase, 3 mol% BG, to reach a disordered, ER state while also requiring the largest electric fields to induce an FE phase compared with similarly substituted NBT- x BT samples. This led to a maximum unipolar strain of 0.53% (d 33* = 866 pm/V) for the 0.93NBT-0.07BT-0.04BG composition. The largest strains for each system occurred in compositions that were in the ER region at room temperature. These results demonstrate that the addition of BG most effectively destabilizes the long-range dipole order near the MPB composition of NBT-BT, which results in an enhanced electric field-induced strain.

In vitro production (IVP) has been shown to affect embryonic gene expression and often result in large offspring syndrome (LOS) in cattle and sheep. To dissect the effects of in vitro maturation, fertilization and culture on bovine embryos, we compared the expression profiles of single blastocysts generated by: (1) in vitro maturation, fertilization and culture (IVF); (2) in vivo maturation, fertilization and in vitro culture (IVD); and (3) in vivo maturation, fertilization and development (AI). To conduct expression profiling, total RNA was isolated from individual embryos, linearly amplified and hybridized to a custom bovine cDNA microarray containing approximately 6,300 unique genes. There were 306, 367, and 200 genes differentially expressed between the AI and IVD, IVF and IVD, and AI and IVF comparisons, respectively. Interestingly, 44 differentially expressed genes were identified between the AI embryos and both the IVF and IVD embryos, making these potential candidates for LOS. There were 60 genes differentially expressed between the IVF embryos and the AI and IVD embryos. The Gene Ontology category "RNA processing" was over-represented among the genes that were down-regulated in the IVF embryos, indicating an effect of in vitro oocyte maturation/fertilization on the ability to transcribe maternal RNA stores. A culture effect on the expression of genes involved in translation was also observed by the comparison of AI with IVD embryos.