Consensus sequences for good and poor removal of uracil from double stranded DNA by uracil-DNA glycosylase.

We have purified uracil DNA-glycosylase (UDG) from calf thymus 32,000-fold and studied its biochemical properties, including sequence specificity. The enzyme is apparently closely related to human UDG, since it was recognised by a polyclonal antibody directed towards human UDG. SDS-PAGE and western analysis indicate an apparent M(r) = 27,500. Bovine UDG has a 1.7-fold preference for single stranded over double stranded DNA as a substrate. Sequence specificity for uracil removal from dsDNA was examined for bovine and Escherichia coli UDG, using DNA containing less than one dUMP residue per 100 nucleotides and synthetic oligonucleotides containing one dUMP residue. Comparative studies involving about 40 uracil sites indicated similar specificities for both UDGs. We found more than a 10-fold difference in rates of uracil removal between different sequences. 5'-G/CUT-3' and 5'-G/CUG/C-3' were consensus sequences for poor repair whereas 5'-A/TUAA/T-3' was a consensus for good repair. Sequence specificity was verified in double stranded oligonucleotides, but not in single stranded ones, suggesting that the structure of the double stranded DNA helix has influence on sequence specificity. Rate of uracil removal appeared to be slightly faster from U:A base pairs as compared to U:G mis-matches. The results indicate that sequence specific repair may be a determinant to be considered in mutagenesis

Changing statistics of storms in the North Atlantic?

Problems in the present discussion about increasing storminess in the North At- lantic area are discussed. Observational data so far available do not indicate a change in the storm statistics. Output from climate models points to an intensified storm track in the North Atlantic, but because of the limited skill of present—day climate models in simulating high-frequency variability and regional details any such “fore— cast” has to be considered with caution. A downscaling procedure which relates large—scale time-mean aspects of the state of the atmosphere and ocean to the local statistics of storms is proposed to reconstruct past variations of high-frequency variability in the atmosphere (storminess) and in the sea state (wave statistics). First results are presented

Changing statistics of storms in the North Atlantic?

Problems in the present discussion about increasing storminess in the North Atlantic area are discusesd. Observational data so far available do not indicate a change in the storm statistics. Output from climate models points to an itensified storm track in the North Atlantic, but because of the limited skill of present-day climate models in simulating high-frequency variability and regional details any such 'forecast' has to be considered with caution. A downscaling procedure which relates large-scale time-mean aspects of the state of the atmosphere and ocean to the local statistics of storms is proposed to reconstruct past variations of high-frequency variability in the atmosphere (storminess) and in the sea state (wave statistics). First results are presented. (orig.)SIGLEAvailable from TIB Hannover: RR 1347(116) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman