A simple electrophoresis system for multiple agarose slab gels

Genotypic differences between the mouse adenovirus strains FL and K87

Restriction endonuclease analysis was used to compare the genome of mouse adenovirus (MAd) strains FL and K87. Large differences were found between the Kpn I, PaeR7, Pvu I, Sal I and Sma I restriction profiles of the prototype strains. MAd-FL and MAd-K87 thus represent two distinct species of mouse adenovirus.

Genome typing of mouse adenoviruses

Restriction endonuclease cleavage site analysis was used to differentiate between mouse adenovirus (MAV) types 1 and 2 strains. Viral DNA of suitable purity and quantity for multiple enzymatic digestions was obtained from cloned CMT-93 mouse tumor cells infected with each type of MAV. Clear differences between the MAV-1 (FL) and MAV-2 (K87) genomes were observed after cleavage with restriction enzymes such as BglII, EcoRI, and PaeR7. Fast electrophoresis of DNA fragments in miniature agarose slab gels allowed rapid and unequivocal identification of the MAV strains. This relatively simple and accurate method should be quite useful to determine the different modes of transmission of mouse adenoviruses and their presence in various animal populations.

Increased DNA topoisomerase I activity in aging human cell chromatin

Chromatin-associated DNA topoisomerase I activity was measured in human diploid fibroblasts during in vitro aging. No difference was detected as a function of cell age in the nicking and the closing activities of the DNA-unwinding enzyme. The capacity of type-I topoisomerase to relax superhelical DNA molecules was, however, increased in aged cells. An age-related increase in nucleoprotein content was also observed.

Interspecific differences between the DNA restriction profiles of canine adenoviruses

Identification of canine adenovirus-1 ( CAV -1) and canine adenovirus-2 ( CAV -2) strains was done by electrophoresis of restriction endonuclease-fragmented viral DNA. Results obtained with this sensitive and reproducible technique clearly show that CAV -2 is not a variant of CAV -1 but a distinct virus.

Separation of viral DNA molecules in horizontal agarose slab gels using a new type of wick

A new type of rayon fiber wick was used to establish uniform electrical paths between agarose slab gels and the electrodes of a horizontal electrophoresis apparatus. Separation of viral DNA molecules, either digested with restriction enzymes or relaxed with eukaryotic topoisomerases, was achieved easily at both low and relatively high voltage.

Mammalian cells contain a DNA-recombining activity that can be dissociated from topoisomerase activity

The role of the topoisomerase enzyme in DNA recombination was investigated by extracting chromosomal deoxyribonucleoproteins from a variety of cultured mammalian cells and assaying for the formation of recombinant DNA structures. Although each of the crude deoxyribonucleoprotein preparations contained topoisomerase activity, they did not all contain DNA-recombining activity. A distinct, perhaps novel, enzyme may therefore promote DNA recombination in these cell-free systems.