Cloning Dolly (pp. 162-164)
Control of Gene Expression by Cytoplasmic Factors (p. 167/168)
|p. 153, Fig. 7.5a: The arrow supposed to mark the chromocenter has been omitted in print. It is shown on this page to the right in a black-and-white version of the same picture.|
p. 153, Fig. 7.5b: Labels from another photograph have been used inadvertently. The bands of highly coiled chromatin are the dark horizontal layers. The interbrands are the areas between the bands, with straight chromatin strands running more or less vertically.
p. 165, left column, the first three lines should read: "gestation period of mice, further basic research on mammalian cloning will proceed much faster than it would with large mammals."
Lanza R. and Rosenthal N. (2004) The stem cell challenge. Scientific American June 2004: 93-99
Rideout W.M. III, Eggan K. and Jaenisch R. (2001) Nuclear cloning and epigenetic reprogramming of the genome. Science 293: 1093-1098
Rideout WM 3rd, Hochedlinger K, Kyba M, Daley GQ, Jaenisch R. (2002) Correction of a genetic defect by nuclear transplantation and combined cell and gene therapy. Cell 109(1): 17-27.
By genetic transformation of embryonic stem cells obtained after nuclear transfer from immonodeficient mice, the authors have developed a model for human cell replacement therapy.
Kikyto N., Wade P.A., Guschin D., Ge H. and
Wolffe A.P. (2000) Active remodeling of somatic nuclei in egg
cytoplasm by the nucleosomal ATPase ISWI. Science 289:
Nuclear transfer experiments were designed to test whether differentiated cells retain a full complement of genetic information. This is a very demanding test, as it also requires that all kinds of genes be accessible to the transcriptional machinery at the appropriate time. Quite possibly, this additional requirement is the reason why the success rate of nuclear transfer experiments is so low. Researchers are therefore focussing now on the "remodeling" process that nuclei undergo upon transfer to egg cytoplasm. The remodeling involves the loss of nuclears protein as well as the uptake of new cytoplasmic proteins. The authors of this study have developed a system for studying this process in vitro. They found that TATA-binding protein, a major general transcription factor (see p. 412/413 of text), is released as part of the remodeling process. The release requires a nucleosomal adenosine triphosphatase known as ISWI.
Wakayama T., Tabar V., Rodriguez I., Perry
A.C., Studer L. and Mombaerts P. (2001) Differentiation of
embryonic stem cell lines generated from adult somatic cells by
nuclear transfer. Science 292: 740-743
One of the expected benefits of therapeutic human cloning is to provide any given patient suffering from a degenerative disease such as diabetes or Parkinson's with isogenic replacement cells, which are not rejected by the patient's immune system. This study describes essential parts of this procedure using the mouse model. The investigators obtained 35 cell lines by transfering nuclei from various somatic cells into enucleated eggs, which were then grown into blastocysts to harvest the inner cells mass. In vitro, these nuclear transfer-derived embryonic stem (ntES) cells gave rise to a wide range of somatic cell types including dopaminergic and serotonergic neurons. When added to fertilization-derived blastocysts, the ntES cells gave rise to both male and female germ cells, which contributed to viable offspring. The results demonstrate that mouse ntES cells are totipotent.
Go back to Home Page
Website maintained by Dr. Klaus Kalthoff
E mail: firstname.lastname@example.org
Last modified: 29 August 2006