[Phenotypic characteristics of temperature-sensitive mutants of bacteriophage T4 in gene 19]

The order of three thermosensitive mutations in gene 19 is determined and compared with the character of defective structures observed in an electrone microscope study of the lysates obtained in non-permissive and semi-permissive conditions. The degree of defectiveness of core polymerization increases if the mutation is located near the beginning of the gene. In one the combinations among these mutants the interallelic complementation is found. The mechanism of complementation is discussed on the basis of the electrone microscopic pattern. The polymerization of core protein in vivo starts from the base plate.