. Cell heredity. Cytogenetics. RECOMBINATION IN VIRUSES AND BACTERIA sni-iv sni-1 Sm-la or-16 I. sm-ic I â ^âfr^i I sui-N sni-21 â â âV-^i I siii-A^ ] Slll-iV FIGURE A scheme for the structure of the DNA in the strains listed in Table , which will explain the results obtained. Only a few interactions are indicated as an example of how the model works. amounts of capsule; each one yields DNA which will transform R cells only to its own type. But when these DNA's are used to transform one or another of the intermediate types, results of the sort shown in Table are obtained. At first
. Cell heredity. Cytogenetics. RECOMBINATION IN VIRUSES AND BACTERIA sni-iv sni-1 Sm-la or-16 I. sm-ic I â ^âfr^i I sui-N sni-21 â â âV-^i I siii-A^ ] Slll-iV FIGURE A scheme for the structure of the DNA in the strains listed in Table , which will explain the results obtained. Only a few interactions are indicated as an example of how the model works. amounts of capsule; each one yields DNA which will transform R cells only to its own type. But when these DNA's are used to transform one or another of the intermediate types, results of the sort shown in Table are obtained. At first glance these seem indeed to be complex re- sults, but there is a very simple explanation. You will note that most transformations are to the same type as that of the DNA employed; these are called autogenic. But some are to the wild-type condition and are called allogenic. The wild type was not involved in the experiment, however, either as the treated cell or as the source of the DNA, and mutations to that condition are not frequent enough to account for the allogenic transformations. This suggests that recombination is at work. If we assume that the different types have DNA's of the structure shown in Figure , allogenic transformation can be explained on the basis of a copy-choice mechanism of DNA duplication. The validity of this model is yet to be attested, but it is clearly established that all trans- formants contain DNA characteristic of their phenotypes. Therefore new types of DNA are produced in transformation by some mechanism of recombination. These new SIII-N types do not subsequently break down into their component parts in pneumococcus but in another bacterium, Hemophilus influenzae, where the situation is formally the same, they do so. DNA from an Hemophilus strain with an antigenic capsule of type a will trans-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and ap
Size: 1866px × 1339px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollectionbiodiv, bookpublishernewyorkwiley
