PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 4564207

Precursor and product in bacteriophage lambda recombination.

N E Melechen·T A Hudnik-Plevnik
View original source ↗Export metadata ↓

Abstract

Analyses of the time of recombination in bacteria infected with phage lambda and in spheroplasts infected with purified phage lambda DNA indicate a preponderance of recombination occurring before replication ("early recombination") after infection with tandem dimers formed in vitro compared to linear monomer DNA and phage infections. Among the early recombinants is a large fraction of cells that produces one recombinant type exclusively. Two suggestions are discussed-that a dimer-like molecule is the precursor of the recombinant progeny molecule and that one recombinant chromosome is the frequent or exclusive product of a recombinational event.

Explore related subjects

Centrifugation, Density GradientColiphagesDNA ReplicationDNA, ViralEscherichia coliLysogenyMolecular WeightRecombination, GeneticSpheroplastsThymidineTritiumVirus ReplicationJournal Article

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

N E Melechen, T A Hudnik-Plevnik. 1972. Precursor and product in bacteriophage lambda recombination.. https://doi.org/10.1073/pnas.69.11.3195

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2003

Probing conformation and conformational change in proteins is optimally undertaken in relative mode.

Hydrodynamic bead modelling has been widely used in attempts to assess the 3D conformation of proteins in solution. Initially, simple models employing only a small number of beads were used, with a considerable degree of success. Latterly, high-resolution bead models based upon atomic coordinates have been developed, and much more sophisticated questions can in principle be addressed. A detailed analysis is presented of the errors involved in the generation of such models and associated prediction of (translational friction) parameters, and in the practical measurement of these parameters for comparison. It is shown that in most cases, for a particle of only moderate asymmetry, the errors are such that it is not feasible to determine, on an absolute basis, which of a range of candidate conformers is the "correct" one. However, when the properties of the candidate conformers can be compared in relation to those of a "paradigm conformer", whose structure in solution, on the basis of external evidence, can be accepted as correct, then errors cancel and very precise comparisons become possible. The generation of 3D bead models (and hence 3D data files) for a range of candidate conformers is a simple matter, using the existing program MacBEADS, further facilitated by a 3D display module (pro Fit).

Centrifugation, Density Gradient↗
PubMed2003

Correlation of SEC/MALLS with ultracentrifuge and viscometric data for chitosans.

Attempts have been made to correlate estimates of molecular weight for a group of cationic polysaccharides known as chitosans between the highly popular technique of size-exclusion chromatography coupled to multi-angle laser light scattering, "SEC-MALLS", and the less convenient but more established technique of sedimentation equilibrium in the analytical ultracentrifuge. Four pharmaceutical grade chitosans of various molecular weights and degrees of acetylation (4-30%) were chosen. Better correlation than previous was achieved, although some batch variability was observed. Despite the broad spectrum in degree of acetylation, a log s degrees(20,w) versus log Mw scaling plot appeared to fit a straight line with power-law exponent b=0.25 +/- 0.04, i.e. between the limits of rod (0.15) and coil (0.4-0.5), although this may be the average of a lower b value at low Mw and higher b at high Mw. With regard to viscosity, a logeta versus logMw scaling plot appeared to also fit a straight line with power-law exponent a=0.96 +/- 0.10, again between the coil (0.5-0.7) and rod (1.8) limits.

Centrifugation, Density Gradient↗
PubMed2003

Calculation of the solution properties of flexible macromolecules: methods and applications.

While the prediction of hydrodynamic properties of rigid particles is nowadays feasible using simple and efficient computer programs, the calculation of such properties and, in general, the dynamic behavior of flexible macromolecules has not reached a similar situation. Although the theories are available, usually the computational work is done using solutions specific for each problem. We intend to develop computer programs that would greatly facilitate the task of predicting solution behavior of flexible macromolecules. In this paper, we first present an overview of the two approaches that are most practical: the Monte Carlo rigid-body treatment, and the Brownian dynamics simulation technique. The Monte Carlo procedure is based on the calculation of properties for instantaneous conformations of the macromolecule that are regarded as if they were instantaneously rigid. We describe how a Monte Carlo program can be interfaced to the programs in the HYDRO suite for rigid particles, and provide an example of such calculation, for a hypothetical particle: a protein with two domains connected by a flexible linker. We also describe briefly the essentials of Brownian dynamics, and propose a general mechanical model that includes several kinds of intramolecular interactions, such as bending, internal rotation, excluded volume effects, etc. We provide an example of the application of this methodology to the dynamics of a semiflexible, wormlike DNA.

Centrifugation, Density Gradient↗