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Biomedical subjects

E H Szybalski

Publications and source records attributed to E H Szybalski.

5 recordsLinked to original sources
PubMed1979

A comprehensive molecular map of bacteriophage lambda.

Physical and genetic mapping of deletion mutations has been correlated with the available molecular sizes of the lambda gene products and the DNA base sequence to construct a comprehensive molecular map of the phage lambda genome. The physical length of the DNA making up the left arm from the cos site through gene J is not sufficient to account in a nonoverlapping manner for all the proteins of the sizes reported to be coded, especially in the Nu1--C region. In the right arm all the coding capacity has not been accounted for, and it appears to be oversaturated only in the gam-ral region. The positions of several IS and Tn elements, and of restriction endonuclease cleavage sites are specified.

Bacteriophage lambda↗
PubMed1975

Intermolecular linking and fragmentation of DNA by beta-propiolactone, a monoalkylating carcinogen.

Brief exposure to beta-propiolactone (BPL) increases the sedimentation rate of purified Escherichia coli DNA in neutral and alkaline sucrose gradients. However, when electrophoresed in polyacrylamide-agarose gels, this BPL-treated DNA moves ahead of the control. Longer incubation with BPL gives rise to two new fractions, the first one sedimenting as a heterogeneous material of 6-8S, and the second one of very high sedimentation velocity. In acrylamide-agarose gels, the first fraction is again recovered in the 6-8S area, while the second fraction does not enter the gel at all. The DNA at this stage is hyperchromic in ultraviolet light suggesting that as much as 20% may be denaturated. Coliphage lambda DNA treated briefly with BPL and spread in a protein monolayer appears under the electron microscope as a rigid, extended molecule, up to 15% longer than the control DNA, and usually in compact, folded configurations suggesting intramolecular linking. After longer exposure, localized denaturation associated with single-strand breaks is observed. The single-stranded "whiskers" then interact with other DNA molecules, creating highly complex branched networks of single- and multi-stranded DNA. The possible relevance of these observations to the mechanisms involved in carcinogenesis and mutagenesis is considered.

Alkylating Agents↗
PubMedDate not supplied

A physical map of the Escherichia coli bio operon.

The endpoints of the Escherichia coli bio DNA insertions in 24 lambda bio transducing phage were mapped electron micrographically in heteroduplexes of the type lambda bio/lambda att2, which permit simultaneous measurement of the lambda deletion and bio insertion endpoints. A physical map of the bio operon was constructed and correlated with the genetic map, the molecular sizes of the bio gene products, and the restriction map. The order att lambda-bioA-pBopA-bioBFCD-uvrB was confirmed. The maximum size of the bio operon was estimated at 5.5 kb, and the locus was found to be fully saturated with genes. There appears to be little space between the bioA gene and att lambda, while bioD mapped within 0.7 kb from uvrB. The size of the uvrB locus was estimated not to exceed 2.6 kb.

Bacteriophage lambda↗