Abstract: Epithelial cells expressing foreign genetic material are described. The foreign genetic material can be DNA or RNA which does not occur in epithelial cells; DNA or RNA which occurs in epithelial cells but is not expressed in them at levels which are biologically significant; DNA or RNA which occurs in epithelial and has been modified so that it is expressed in epithelial cells; and any DNA or RNA which can be modified to be expressed in epithelial cells, alone or in any combination thereof. In addition, epithelial cells of the present invention can express genetic material encoding a selectable marker by which cells expressing the foreign genetic material can be expressed.
Type:
Grant
Filed:
July 9, 1986
Date of Patent:
September 19, 1989
Assignee:
Whitehead Institute for Biomedical Research
Abstract: Yeast strains are transformed with, and selected for, using DNA fragments encoding a gene function not present in the wild-type yeast strains. The invention requires transforming the yeast with DNA fragments which comprise the gene function which the wild-type yeast strain is lacking; regeneration of the transformants on a non-selective regeneration medium; then selection of those colonies which are capable of growth on a carbon and energy source which requires expression of the gene function provided by the DNA fragment. Thus, transformation with such DNA fragments allows for positive selection of transformed strains.