435 / | HD | CHEMISTRY: MOLECULAR BIOLOGY AND MICROBIOLOGY |
440 | DF | PROCESS OF MUTATION, CELL FUSION, OR GENETIC MODIFICATION {6} |
441 | DF | .~ Mutation employing a chemical mutagenic agent {4} |
444 | .~.~ By use of alkylating agent (e.g., nitrosoguanidine, etc.) |