Fig. 3. Disruption of the ulp1 gene. (A) ulp1 disruption strategy. A 1.1 kb BamHI-SalI fragment within the ulp1 coding sequence was replaced with the ura4 gene. (B) Microscopic analysis of ulp1-null cells. Wild-type, sp.011, (a) and ulp1.d, sp.651, (b) cells were fixed in 70% ethanol, stained with DAPI and analysed using a Zeiss Axioskop 2 microscope. (C-E) Response of ulp1-null cells to UV and ionising radiation and the DNA synthesis inhibitor HU. Wildtype (sp.011) and ulp1.d (sp.651) were exposed to a range of doses of UV (C), ionising radiation (D) or 20 mM HU and samples taken over 10 hours (E). (F) Epistasis analysis. Wild-type (sp.011), ulpl.d (sp.651), rad17.d (sp.310) and ulp1.d,rad17.d (sp.666) cells were subject to UV radiation.