The probable nuclear origin of certain of the bodies released from yeast protoplasts by ultrasonic treatment

Relatively fragile parts of the yeast cell have been isolated by releasing them from protoplasts by means of brief ultrasonic treatment. Particular attention has been paid to the possibility of separating DNA and RNA in association with particles of visible dimensions. The primary vacuole and various accessory vacuoles, each in a state of relative preservation, figures prominently among the products released at pH 6–7, whereas at pH 5 the most stable product exhibited a characteristic refractile cap borne by a membrane which, in various instances, could be clearly discerned as a spheroidal vesicle of about 2–3 μ diameter distinct from the main vacuole.Two further methods of isolating the refractile bodies were developed, one involving the use of formamide as a suspending medium and the other a preliminary lysis of the protoplasts. In each case the refractile bodies, stabilized in the presence of magnesium and calcium ions, were found to be associated with an approximately characteristic amount of DNA probably representing the whole of that found in the protoplast. It is suggested that these bodies are derived fairly directly from the yeast nucleus, which appears to contain only about 1 per cent of DNA by weight, but several times this amount of RNA.