Isolation of Nucleoli

Studies on the nucleolus have been extensive in biology and medicine since its first description in eucaryotic cells (14) . However, in biochemical terms, definition of nucleolar function requires procedures for massive isolation of nucleoli, a technique which has been refined a great deal since the first attempts were described (15, 20) . The nearest approximation of presently employed methods resulted from the work of Maggio et al . (11, 12) and Muramatsu et al . (17) : in both cases, it involved the use of sonic oscillation to disrupt purified nuclear preparations. Although alternative procedures have been proposed (4, 7, 19), most of the standard methods known to produce a high yield of purified nucleoli derived from sonication procedures . A new investigation of the variables of the methods employing sonication led to the procedure described in the present paper . This method has proven to be the most satisfactory in ascites tumor cells as it meets completely the following requirements : a high recovery of purified nucleoli, ultrastructural integrity, and biochemical preservation of macromolecular components .