Purification of nuclei from a flagellate protozoan, Trypanosoma brucei

A simple and rapid technique is described for the isolation of nuclei from the flagellate protozoan Trypanosoma brucei. Cells were disrupted by nitrogen cavitation in the presence of hexylene glycol which enhances nuclear stability. Isolated nuclei were separated from nuclei trapped with cytoskeletal fragments and flagellae by Percoll density gradient centrifugation. Centrifugation in a medium with increased sucrose concentration greatly improved the separation of free nuclei from those trapped in cell debris. The isolation procedure resulted in the recovery of 34% of the nuclei present in the whole cell suspension. Electron microscopic and chemical analysis indicated that the recovered nuclei were in good condition and were highly purified.