Our paper describing a new allele of the Drosophila WRN-like exonuclease DmWRNexo and on it's biochemical characterisation is finally out in print (its been available online for some time):
Boubriak, I., Mason, P. A., Clancy, D. J., Dockray, J., Saunders, R. D. C., Cox. L. S. 92009) DmWRNexo is a 3′–5′ exonuclease: phenotypic and biochemical characterization of mutants of the Drosophila orthologue of human WRN exonuclease. Biogerontology 10; 267-277 DOI: 10.1007/s10522-008-9181-3
A pdf of this paper is available from the Biogerontology website, but will require a subscription.