Transfection of the cloned human excision repair gene ERCC-1 to UV-sensitive CHO mutants only corrects the repair defect in complementation group 2 mutants.

The human DNA-excision repair gene ERCC-1 is cloned by its ability to correct the excision-repair defect of the ultraviolet light- and mitomycin-C-sensitive CHO mutant cell line 43-3B. This mutant is assigned to complementation group 2 of the excision-repair-deficient CHO mutants. In order to establish whether the correction by ERCC-1 is confined to CHO mutants of one complementation group, the cloned repair gene, present on cosmid 43-34, was transfected to representative cell lines of the 6 complementation groups that have been identified to date. Following transfection, mycophenolic acid was used to select for transferants expressing the dominant marker gene Ecogpt, also present on cosmid 43-34. Cotransfer of the ERCC-1 gene was shown b

A CHO mutant, UV40, that is sensitive to diverse mutagens and represents a new complementation group of mitomycin C sensitivity

A new mitomycin C (MMC)-sensitive rodent line, UV40, has been identified in the collection of ultraviolet light- (UV-) sensitive mutants of Chinese hamster ovary (CHO) cells isolated at the previous Facility for Automated Experiments in Cell Biology (FAECB). It was isolated from an UV mutant hunt using mutagenesis of AA8 cells with the DNA intercalating frameshift mutagen ICR170. It is complemented by CHO-UV-1, irs1, irs3, irs1SF, MC5, V-C8 and V-H4 with respect to its MMC sensitivity based on cell survival, Despite having approx. 4 x normal UV sensitivity and increased sensitivity to UV inhibition of DNA replication, it has near-normal incision kinetics of UV irradiated DNA, and normal (6-4) photoproducts removal. It also is not hypermutable by UV, and shows near normal levels of UV inhibition of RNA synthesis. UV40 also has approx. 11 x, 10 x, 5 x and 2 x AA8 sensitivity to MMC, ethyl methanesulfonate (EMS), methyl methanesulfonate (MMS), and X-rays, respectively. Thus, its defect apparently does not involve nucleotide excision repair but rather another process, possibly in replicating past lesions. The spontaneous chromosomal aberration frequency is elevated to 20% in UV40, and the baseline frequency of sister chromatid exchange is also ~ 4-fold increased. The phenotype of UV40 appears to differ from all other rodent mutants that have so far been described

Workshop on DNA repair.

A workshop on DNA repair with emphasis on eukaryotic systems was held, under the auspices of the EC Concerted Action on DNA Repair and Cancer, at Noordwijkerhout (The Netherlands) 14-19 April 1991. The local organization of the meeting was done under the auspices of the Medical Genetic Centre South-West, The Netherlands (MGC), c/o Department of Radiation Genetics and Chemical Mutagenesis, University of Leiden (The Netherlands). Local organizers were: D. Bootsma (chairman), W. Ferro, J.H.J. Hoeijmakers, A.R. Lehmann, P.H.M. Lohman, L. Mullenders, and A.A. van Zeeland (secretarial assistance: Mrs. C. Escher-van Heerden and Mrs. R. Bontre). Over 190 scientists participated, and the format of the meeting followed that of the 1987 workshop on the 'Molecular Aspects of DNA Repair' (Friedberg et al., 1987). Plenary review talks in the mornings were followed, in the afternoon, by poster viewing in three or four parallel sessions. Groups of 15-20 posters were discussed in detail, and later on, in plenary sessions, chairpersons of the poster discussions reviewed the afternoons' posters. The principal themes of the meeting were the isolation and characterisation of repair genes and proteins, repair in specific sequences, consequences of defective DNA repair, and new methods for detecting DNA damage and repair. Remarkable progress has been made recently in all of these areas, and many exciting new results were presented. It is impossible to summarize all contributions to this (intensive) one-week meeting. Therefore, and for the sake of coherence, presentations that did not fit easily into any of the general themes of the meetings have not been included