Factors affecting zero background frequency of sister-chromatid exchange in mosquito cells

A background level of sister-chromatid exchange (SCE) is found in mammalian cell. However, in the somatic cell of Drosophila melanogaster, there was no spontaneous SCE if a minimum concentration of bromodeoxyuridine (BrdU) was used. In this communication we report that in a mosquito (Aedes albopictus) cell line (C6/36), some cell also have no background SCE (0-SCE). Subclones of high (44%) or low (12%) frequency of 0-SCE cells were obtained, but none of them contained 100% 0-SCE cells. Increasing frequency of SCE/cell concomitant with decreasing frequency of 0-SCE cells was observed by raising the BrdU concentration in the culture medium during the first cell cycle, culturing cell at lower density and depleting reduced glutathione (GSH) with buthionine sulfoximine