Altering Genotype and Phenotype by DNA-Mediated Gene Transfer

TLDR

DNA-mediated gene transfer introduces new genetic material into cells, often altering their phenotype. Transformation functions as an in vivo assay to probe gene function and to dissect complex heritable phenotypes by distinguishing phenotypic changes from DNA alterations. The introduced DNA integrates into the recipient chromosome. Transformed DNA integrates at variable chromosomal sites, and its expression can restore wild‑type phenotypes; selectable genes such as APRT or TK have been isolated using this approach.

Abstract

Transformation, or DNA-mediated gene transfer, permits the introduction of new genetic information into a cell and frequently results in a change in phenotype. The transforming DNA is ultimately integrated into a recipient cell chromosome. No unique chromosomal locations are apparent; different lines contain the transforming DNA on different chromosomes. Expression of transformed genes frequently results in the synthesis of new polypeptide products which restore appropriate mutant cells to the wild-type phenotype. Thus transformation provides an in vivo assay for the functional role of DNA sequence organization about specific genes. Transforming genes coding for selectable functions, such as adenine phosphoribosyltransferase or thymidine kinase, have now been isolated by utilizing transformation in concert with molecular cloning. Finally, transformation may provide a general approach to the analysis of complex heritable phenotypes by permitting the distinction between phenotypic changes without concomitant changes in DNA and functional genetic rearrangements.