Summary

A physical map of Neurospora crassa mitochondrial DNA has been con-structed using specific fragments obtained with restriction endonucleases. The DNA has 5 cleavage sites for endonuclease Bam HI, 12 for endonuclease Eco RI and more than 30 for endonuclease Hind III. The sequence of the Eco RI and Barn HI fragments has been established by analysis of partial fragments. By digestion of the Eco RI fragments with Barn HI, a complete overlapping map has been constructed. The position of the largest Hind III fragment on this map has also been determined. The map is circular and the added molecular weight of the fragments is 40 • 106, which is in good agreement with earlier measure-ments on intact DNA, using the electron microscope