Biomaterial Database

Isolation of circular deoxyribonucleic acid from Salmonella typhosa hybrids obtained from matings with Escherichia coli Hfr donors. 1971

R W Leavitt, and J A Wohlhieter, and E M Johnson, and G E Olson, and L S Baron

Heterozygous, partial diploid Salmonella typhosa hybrids obtained from matings with Escherichia coli K-12 Hfr strains were observed to contain supercoiled, circular deoxyribonucleic acid (DNA) when examined by the dye-buoyant density method. Examination of one such S. typhosa hybrid after its loss, by segregation, of the inherited E. coli genetic markers revealed a concurrent loss of its supercoiled circular DNA. Subsequent remating of this segregant with various E. coli Hfr strains resulted in the reappearance of the circular DNA. Molecular weight determinations of circular DNA molecules isolated from a number of S. typhosa partial diploid hybrids were made by sucrose density gradient ultracentrifugation and electron microscopy. These studies revealed a range of molecular sizes among the various hybrids examined, but each hybrid exhibited only a single characteristic size for its contained circular DNA. The range of size is consistent with the presence in each hybrid of a different length of E. coli chromosome. It was concluded that the E. coli Hfr genetic segments transferred to these S. typhosa hybrids were conserved, in the diploid state, in the form of supercoiled, circular DNA molecules.

UI	MeSH Term	Description	Entries
D008854	Microscopy, Electron	Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.	Electron Microscopy
D008970	Molecular Weight	The sum of the weight of all the atoms in a molecule.	Molecular Weights,Weight, Molecular,Weights, Molecular
D010617	Phenanthridines
D002499	Centrifugation, Density Gradient	Separation of particles according to density by employing a gradient of varying densities. At equilibrium each particle settles in the gradient at a point equal to its density. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Centrifugations, Density Gradient,Density Gradient Centrifugation,Density Gradient Centrifugations,Gradient Centrifugation, Density,Gradient Centrifugations, Density
D002874	Chromosome Mapping	Any method used for determining the location of and relative distances between genes on a chromosome.	Gene Mapping,Linkage Mapping,Genome Mapping,Chromosome Mappings,Gene Mappings,Genome Mappings,Linkage Mappings,Mapping, Chromosome,Mapping, Gene,Mapping, Genome,Mapping, Linkage,Mappings, Chromosome,Mappings, Gene,Mappings, Genome,Mappings, Linkage
D002876	Chromosomes, Bacterial	Structures within the nucleus of bacterial cells consisting of or containing DNA, which carry genetic information essential to the cell.	Bacterial Chromosome,Bacterial Chromosomes,Chromosome, Bacterial
D004171	Diploidy	The chromosomal constitution of cells, in which each type of CHROMOSOME is represented twice. Symbol: 2N or 2X.	Diploid,Diploid Cell,Cell, Diploid,Cells, Diploid,Diploid Cells,Diploidies,Diploids
D004269	DNA, Bacterial	Deoxyribonucleic acid that makes up the genetic material of bacteria.	Bacterial DNA
D004926	Escherichia coli	A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.	Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
D005827	Genetics, Microbial	A subdiscipline of genetics which deals with the genetic mechanisms and processes of microorganisms.	Microbial Genetics,Genetic, Microbial,Microbial Genetic