Viruses: Bacterial, Animal, and Plant 407 



SUMMARY AND CONCLUSIONS 



There are mutational "hot spots" at the nucleotide level; these are different for mutants 

 occurring spontaneously and for those induced by various chemical mutagens. 



Mutation is defined operationally as any detectable novel change affecting the chemical 

 constitution, mutability, replication, phenotypic effect, or recombination of one or more 

 nucleotides. 



Whole nucleotide mutations include additions and losses of single whole nucleotides; 

 subnucleotide mutations may involve transitions and transversions. It is hypothesized 

 that the components of a nucleotide serve as sites for mutation. 



RNA is the sole carrier of genetic properties in certain viruses. Some RNA viruses can 

 undergo genetic recombination. 



REFERENCES 



Benzer, S., and Freese, E., "Induction of Specific Mutations with 5-Bromouracil," Proc. 

 Nat. Acad. Sci., U.S., 44:112-119, 1958; reprinted in Papers on Bacterial Viruses, 

 Stent, G. (Ed.), Boston, Little, Brown, 1960, pp. 220-227. 



Burnet, F. M., and Stanley, W. M. (Eds.), T/ie Viruses; Vol. 1, General Virology, 609 pp.; 

 Vol. 2, Plant and Animal Viruses, 408 pp.; Vol. 3, Animal Viruses, 428 pp. New 

 York, Academic Press, 1959. 



Fraenkel-Conrat, H., and Ramachandran, L. K., "Structural Aspects of Tobacco Mosaic 

 Virus," Advances in Protein Chemistry, 14:175-229, 1959. 



Fraenkel-Conrat, H., and Williams, R. C, "Reconstitution of Tobacco Mosaic Virus from 

 Its Inactive Protein and Nucleic Acid Components," Proc. Nat. Acad. Sci., U.S., 

 41:690-698, 1955; reprinted in Classic Papers in Genetics, Peters, J, A. (Ed.), Engle- 

 wood Cliffs, N.J., Prentice-Hall, 1959, pp. 264-271. 



Freese, E., "The Difference Between Spontaneous and Base-Analogue Induced Mutations 

 of Phage T4," Proc. Nat. Acad. Sci., U.S., 45:622-633, 1959. 



Freese, E., Bautz, E., and Freese, E. B., "The Chemical and Mutagenic Specificity of Hy- 

 droxylamine," Proc. Nat. Acad. Sci., U.S., 47:845-855, 1961. 



Gierer, A., "Ribonucleic Acid as Genetic Material of Viruses," in Microbial Genetics, 

 Hayes, W., and Clowes, R. C. (Eds.), Cambridge, Cambridge University Press, 1960, 

 pp. 248-271. 



Herskowitz, I. H., "The Production of Mutations in Drosophila Melanogaster with Sub- 

 stances Administered in Sperm Baths and Vaginal Douches," Genetics, 40:76-89 

 1955. 



Lerman, L. S., "Structural Considerations in the Interaction of DNA and Acridines," 

 J. Mol. Biol., 3:18-30, 1961. 



Muller, H. J., Carlson, E., and Schalet, A., "Mutation by the Alteration of the Already 

 Existing Gene," Genetics, 46:213-226, 1961. 



Tsugita, A., Gish, D. T., Young, J., Fraenkel-Conrat, H., Knight, C. A., and Stanley, W. M., 

 "The Complete Amino Acid Sequence of the Protein of Tobacco Mosaic Virus," 

 Proc. Nat. Acad. Sci., U.S., 46:1463-1469, 1960. 



QUESTIONS FOR DISCUSSION 



44.1. Would you expect the mutational hot spots in the rll region to be different after 

 exposing T4 to hydroxy lamine from what they are after T4 is exposed to nitrous 

 acid? Why? 



