Initiation of DNA replication in nuclei and purified DNA by a cell-free extract of Xenopus eggs.

https://www.cell.com/cell/pdf/0092-8674(80)90439-0.pdf

Regulated replication of DNA microinjected into eggs of Xenopus laevis

Publisher Summary This chapter describes the methods for nuclear transplantation in amphibia. The reasons for developing the technique of nuclear transplantation are to test the genetic content of somatic cells and to analyze interactions between nucleus and cytoplasm. The chapter discusses potential applications of this technique. Among multicellular organisms, the large size and ready availability of the eggs and oocytes of amphibia give them great advantages for nuclear transplantation over those of other animals. The techniques are applicable to eggs and oocytes of Xenopus laevis . Minor differences in technique apply to eggs of Ram pipiens . Hormone injection causes fully grown oocytes to be released from the ovary, passed down the oviduct where they are surrounded by jelly, and released into the surrounding water. Eggs, unlike oocytes, can be fertilized and can commence development. The most useful applications of nuclear transplantation methods for investigating the function of chromosomal proteins involve multiple nuclear transfers and the injection of purified genes or chromosomal proteins.

Methods for nuclear transplantation in amphibia.

This is a personal historical account of events leading from the earliest success in vertebrate nuclear transfer to the current hope that nuclear reprogramming may facilitate cell replacement therapy. Early morphological evidence in Amphibia for the toti- or multipotentiality of some nuclei from differentiated cells first established the principle of the conservation of the genome during cell differentiation. Molecular markers show that many somatic cell nuclei are reprogrammed to an embryonic pattern of gene expression soon after nuclear transplantation to eggs. The germinal vesicles of oocytes in first meiotic prophase have a direct reprogramming activity on mammalian as well as amphibian nuclei and offer a route to identify nuclear reprogramming molecules. Amphibian eggs and oocytes have a truly remarkable ability to transcribe genes as DNA or nuclei, to translate mRNA, and to modify or localize proteins injected into them. The development of nuclear transplant embryos depends on the ability of cells t...

/pdf/from-nuclear-transfer-to-nuclear-reprogramming-the-reversal-58zkk2na25.pdf

M.L. Birnstiel

Papers

The replication of purified DNA introduced into living egg cytoplasm