ON THE SPECIFICITY OF THE DESOXYRIBONUCLEIC ACID WHICH INDUCES STREPTOMYCIN RESISTANCE IN HEMOPHILUS

Abstract

The specificity or degree of reactivity of the desoxyribonucleic acid (DNA) which controls streptomycin (SM) resistance was studied among types of Hemophilus influenzae and H. parainfluenzae and among the species, H. influenzae, H. parainfluenzae, and H. suis. The ratio of the number of cells in which SM resistance is induced by a heterologous DNA, to the number induced by a homologous DNA, may approach unity for types within a species; between species it is of a low order. The data suggest that this ratio may be of value as an index of the degree of kinship of the recipient population and that of the donor of the DNA. SM resistance was induced in populations of H. influenzae and H. parainfluenzae by DNA''s derived from SM-resistant cells of at least one heterologous species. Within these 2 species, the ratio of heterospecific to homospecific transformed cells appears to be relatively constant for a given recipient population and independent of the serologic type or strain source of the heterologous species SM resistance DNA. The low proportion of cells in H. influenzae populations transformed by DNA''s derived from SM-resistant H. parainfluenzae and vice versa has been increased 4- to 15-fold by the replication of the heterologous species SM resistance DNA in the heterologous species. An alteration of the heterologous DNA by the host is suggested.