Studies of inheritance in amoebae by the technique of nuclear transfer

Abstract

The methods of classical genetics depend essentially on the reassortment of genes which occurs as a result of meiotic and mating processes. These methods are of great elegance and great power. Upon their success our present theory of inheritance depends. But these methods also have certain weaknesses. These include the following points (1) The study of non-chromosomal inheritance is laborious, though of course not impossible, as has been demonstrated by the remarkable studies of Michaelis (1954). (2) In many instances the setting of the scene for meiosis, and the developments after mating, involve drastic reorganization of the cytoplasm in ways which are unfavourable for detailed analysis of cytoplasmic inheritance. (3) Where mating and meiotic processes do not occur, the classical methods of genetics are useless. This means, for example, that the manifest differences between cell lineages which appear in the course of development cannot be studied by these methods, and to particularize, many of the genetical aspects of malignant growth cannot be analyzed. For reasons such as these I decided about 10 years ago to attempt the study of inheritance by transferring nuclei from cell to cell. In the development of such a programme it is convenient to distinguish between ( a ) the problems of the origin of differentiated cells from a common ancestral cell in the absence of genetic recombination, and ( b ) the problem of maintenance of a given constant state of differentiation.