WO-2, A STABLE ANEUPLOID DERIVATIVE OF CANDIDA-ALBICANS STRAIN WO-1, CAN SWITCH FROM WHITE TO OPAQUE AND FORM HYPHAE

Candida albicans strain WO-2 was isolated as a spontaneous derivative of the white-opaque switching strain WO-1. The electrophoretic karyoty pe of WO-2 lacks two bands which are found in the parent. These bands correspond to one homologue of chromosome 7 and to a translocation pro duct containing parts of chromosomes 6 and 5. Probing a blot of the ka ryotype demonstrated that the genetic material in these bands had been lost, yielding an aneuploid strain. UV-irradiation experiments showed that auxotrophs due to mutation in genes located in this region predo minated, supporting the conclusion that WO-2 is partially haploid. WO- 2 contained about 10% of its genome in the haploid state, and it grew with a doubling time of about twice that of its parent. However, it wa s able to undergo both the yeast-to-hyphal transition and the white-op aque transition. Hence. these processes do not require perfect diploid y.