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C A THOMAS

Publications and source records attributed to C A THOMAS.

18 recordsLinked to original sources
PubMed1964

DNA FROM BACTERIOPHAGE LAMBDA: MOLECULAR LENGTH AND CONFORMATION.

The length of the DNA molecules from wild-type lambda bacteriophage is 17.2 micro, corresponding to a molecular weight of 33 million in the B form. The molecules from a double-deletion mutant of lambda are 23 percent shorter. Both types of molecules join ends at 60 degrees C to form circular molecules or polymers. The point of junction cannot be distinguished by any irregularity in the uniform duplex molecule.

Bacteriophage lambda↗
PubMed1964

THE ARRANGEMENTS OF NUCLEOTIDE SEQUENCES IN T2 AND T5 BACTERIOPHAGE DNA MOLECULES.

The genetic map of T4 (and T2) bacteriophage is circular but the DNA molecule that is liberated by phenol extraction is a linear duplex of polynucleotide chains. If the genetic map is related to the physical structure of the DNA molecule, the problem arises as to how a linear molecule can give rise to a circular map. An explanation can be made on the basis that the bacteriophage liberate molecules which have nucleotide sequences which are circular permutations of each other. Thus, markers which are most distant on one molecules are closest together on another. To test this hypothesis, the middles of T2 and T5 DNA molecules were mechanically deleted and the absence of certain nucleotide sequences was tested by "renaturation" or "reannealing" experiments using columns containing denatured DNA immobilized in agar beads. The results indicate that when the middles are deleted from the T5 DNA molecule, some special sequences are removed; whereas, when the middles are deleted from the T2 DNA molecule, no special group of sequences is removed. This would indicate that T2 molecules begin at different points in their nucleotide sequence, while T5 molecules all begin at the same point. It is likely that this permutation of sequences of T2(T4) molecules is related to the circularity of their genetic map.

Bacteriophages↗
PubMed1959

The release and stability of the large subunit of DNA from T2 and T4 bacteriophage.

T(2) and T(4) bacteriophage have been exposed to various treatments which are known to release the encapsulated DNA. The unseparated reaction products have been examined by autoradiography. The results indicate the presence of one large subunit of DNA (molecular weight 45 x 10(6)) for each former phage particle. Some smaller subunits of molecular weight 12 x 10(6) have been observed. The large subunit is sensitive to very small amounts of DNAase, and is resistant to mixed proteases and cannot be dispersed by banding in cesium chloride density gradients. The sensitivity to fragmentation by P(32) decay and the increase in this sensitivity following heat treatment are best explained by assuming that the large subunit is a duplex of polynucleotide strands over most of its length. The presence of hypothetical non-DNA interconnections is considered.

Bacteriophage T4↗