Somatic cell nuclear transfer (SCNT or cloning) returns a differentiated cell to a totipotent status; a process termed nuclear reprogramming. Reproductive cloning has potential applications in both agriculture and biomedicine, but is limited by low efficiency. To understand the deficiencies of nuclear reprogramming, our research has focused on both candidate genes and global gene expression pat...

A N important question concerning embryonic differentiation is whether the nuclei of somatic cells in different parts of an embryo come to differ genetically from each other during development. It has become possible to investigate this matter since King & Briggs (1955) have shown that nuclear transplantation is a satisfactory technique for testing the developmental potentialities of embryonic ...

This paper reports on electrofusion of Tetrahymena thermophila and on the reorganization of the cytoskeleton in fused cells. Important factors influencing the fusion yield are the number of electric pulses, the strength of alternate current field and cell density. The process of cell fusion consists of a mutual intermingling of cell membranes following their deformation at the contact zone, fol...

Sheep, mice, cattle, goats and pigs have all been cloned by transfer of a donor cell nucleus into an enucleated ovum, and now we add the successful cloning of a cat (Felis domesticus) to this list. However, this cloning technology may not be readily extendable to other mammalian species if our understanding of their reproductive processes is limited or if there are species-specific obstacles.

Compared to sperm nuclei, nuclei from adult somatic cells replicate inefficiently in frog egg extract. In this issue of Cell, Lemaitre et al. (2005) show that pre-exposure of erythrocyte nuclei to a mitotic extract removes this difference, reorganizes the chromatin into shorter loops, and allows replication at much shorter intervals along the DNA. Remarkably, these observations also explain an ...

Two groups of Brangus steers produced by nuclear transplantation cloning were used in parallel studies investigating the impact of calf- and yearling-feeding. The first group (n = 8) were fed as calves (CF; n = 4) or yearlings (YF; n = 4) to a constant age end point of 16 mo. The second group (n = 10) were fed as calves (CF; n = 5) or yearlings (YF; n = 5) to a constant live weight end point (5...

Mutations have been induced in single amoebae by treatment with the powerful mutagen, iV-methyl-iV-nitrosourethane. Three mutants, which differ visibly from the parent strain to the extent that individual amoebae are recognizable and change of characteristics from normal to mutant or mutant to normal can be followed in single cells, are described. These mutant strains have been cultured in the ...

Cloning is a process that produces genetically identical organisms. However, the genomic degree of genetic resemblance in clones needs to be determined. In this report, the genomes of a cloned dog and its donor were compared. Compared with a human monozygotic twin, the genome of the cloned dog showed little difference from the genome of the nuclear donor dog in terms of single nucleotide variat...

We report the first attempt of its kind to study genetic interactions using young Drosophila embryos that are mosaic for wildtype and mutant cells. Using nuclear transplantation we make mosaic embryos in which a patch of cells lacks a particular segmentation gene, A. With antibodies, we than look at the expression of another gene that is known to be downstream of gene A, with respect to the cel...