- Effects of specific antisera on the growth of bacterial viruses. Delbrück, M. (1945). J. Bacteriol. 50:137-150. [TOP OF PAGE]
- The burst size distribution in the growth of bacterial viruses (bacteriophages). Delbrück, M. (1945). J. Bacteriol. 50:131-135. The burst size distribution for the growth of virus alpha on strain "B" of Escherichia coli is determined for single infection. The burst sizes range from below 20 to over 1,000, with broad maximum around 180. ¶ Comparison with the distribution of bacterial sizes in the same culture shows that the wide distribution of burst sizes cannot be accounted for by variations in teh size of the bacteria alone. ¶ Multiple infection with virus alpha gives the same distribution of burst sizes as single infection. ¶ Single and multiple infection with virus delta growing on the same host gives similar distributions, though with higher average burst sizes. [TOP OF PAGE]
- Bacteriophage-resistant mutants in Escherichia coli. Demerec, M., Fano, U. (1945). Genetics 30:119-136. In a single strain, B, of Escherichia coli, changes to resistance to seven strains of bacteriophage (T1 to T7) were studied. A total of 377 mutants was investigated (table 1) , and eight groups were detected. Five of these—B/1, B/1,5, B/3,4, B/3,4,7, and B/6—occur with higher frequency than the other three—B/1,3,4,5, B/6,1,5, and B/7,1,3,4,5. (The numbers following the bar indicate the phages to which the mutant is resistant.) ¶ In addition, 364 mutants were derived from lines already resistant to one or more phages. The cross-resistance pattern in these tests does not significantly differ from the patter obtained in the previous experiments, where mutants were derived from the sensitive B strain. ¶ The rate of mutation to B/(1,5) was approximately 10-8, to B/(3,4) between 10-8 and 10-7, and to B/6 slightly higher. ¶ Extensive tests made with 34 different mutatns representative of the material used in this work indicate that the growth rates of mutants do not differ systematically from that of the original B strain, when they are grown together with it. ¶ The rate of mutation of resistance to a given phage is similar for the B strain and for strains already resistant to some other phage or phages. ¶ These results indicate that mutations to different resistance types are independent of one another and are probably produced by changes comparable to gene mutations. ¶ Evidence indicates that complex mutants resistant to two or more phages may be obtained from B, either by means of a single mutational step or through summation of two ore more changes. ¶ It was found that mutants frequently show morphological differences in colony size, which breed true. At least three colony sizes can be distinguished for each of the eight types of mutants—namely, large, small, and tiny colonies. Altogether about 20 distinguishable mutant types showing some degree of resistance to our seven phages appeared in our experiments. Since many more phages affecting the B strain could be isolated, it is evident that the actual number of mutants affecting resistance is considerably larger. ¶ A correlation between colony size and resistance type was noted. The frequency of small colony types is higher among B/(3,4,7) than among B/(3,4) mutants. [TOP OF PAGE]
- Investigations and estimation of bacteriophages in water. Diénert, F. (1945). C. R. Acad. Sci. ,Paris 221:574-??? [TOP OF PAGE]
- Transmissible variation of plaque-type in bacteriophage. Hershey, A.D., Bronfenbrenner, J.J. (1945). Proc. Soc. Exp. Biol. Med. 49:107-107. [TOP OF PAGE]
- Mutations of bacterial viruses affecting their host range. Luria, S.E. (1945). Genetics 30:84-99. [TOP OF PAGE]
- Genetics of bacterium-bacterial virus relationship. Luria, S.E. (1945). Annals of the Missouri Botanical Garden 32:235-242. [TOP OF PAGE]
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