Nucleotide excision repair in oocyte nuclear extracts from Xenopus laevis

We have developed efficient DNA repair extracts derived from the unusually large nuclei of Xenopus oocytes. These extracts use nucleotide excision rep air (NER) to completely remove bulky adducts from DNA. There is very little or no synthesis on control, undamaged DNA, indicating the extracts do not have significant nonspecific nuclease activity, and repair of cyclobutane p yrimidine dimers (CPDs) occurs in the dark, indicating that NER, and not ph otolyase, is responsible for CPD repair. The extracts can be inactivated wi th antibodies specific to repair proteins and then repair activity can be r estored by adding purified recombinant protein. Here we describe detailed p rotocols for preparing Xenopus nuclear repair extracts. (C) 2000 Academic P ress.