The Role of Symbionts and Autocatalysts in the Genetics of the Ciliates

Abstract

Accumulating evidence supports the theory that kappa is a symbiont, rather than a plasmagene. The inheritance of differentiation in Paramecium is not due either to kappa-type bodies or to plasmagenes, but more likely to autocatalysts of a non-genic nature. This is indicated by the fact that in the two-type mating strains the material basis of differentiation (into a plus or a minus type) is inherited during asexual reproduction but disappears at conjugation, and is then formed de novo presumably under the influence of nuclear genes in conjunction with the local environment. It is possible that the same explanation applies to mating type in the B races, as well as to the four antigenic types (A, B, C, D), but that in these cases the autocatalyst would be of a more persistent type. It would, however, still be non-genic, provided it could arise de novo after having disappeared. It is extremely improbable that a totally new mechanism of heredity, cytoplasmic in nature, has displaced the Mendelian mechanism in...