Nucleic acid hybridization experiments withSpiroplasma citri and the corn stunt and suckling mouse cataract Spiroplasmas

Abstract

Spiroplasma citri and two as yet unclassified mycoplasmas of the genusSpiroplasma, the corn stunt spiroplasma (CSS) and suckling mouse cataract agent (SMCA), were compared by determination of the guanine-plus-cytosine (G+C) content of the DNA and by nucleic acid homology studies. The G+C content ofS. citri, CSS, and SMCA was found to be 26.4, 25.1, and 30.3 mol%, respectively. In hybridization experiments between DNA extracted from the three organisms, a hybridization of 2–3% was demonstrated betweenS. citri and SMCA, while hybridization betweenS. citri and CSS was about 30%. It is concluded on the basis of these findings, together with avialable serological data, that SMCA can be classified as a separate new species of the genusSpiroplasma, but additional work will be required to clarify the status of the CSS.