The influence of different cell cycle stages on survival and mutagenesis in the yeast Schizosaccharomyces pombe

176 17 R. Barale, D. Rusciano and N. Loprieno, Laboratorio di Genetica dell'UniversitY, Pisa (Italy) The influence o f different cell cycle stages on survival and mutagenesis in the yeast Schizosaccharomyces pombe During the cell cycle DNA structure and metabolism reactions are involved at different degrees in physiological variability. Therefore many biological responses of mutagenically treated cells such as survival and mutagenesis can be influenced. The use of synchronized cell populations of the yeast Sehizosaecharomyce8 pombe has allowed the study of the kinetic induction of mutations and cell killing all over an entire cell cycle, employing different mutagens. The role of DNA metabolism and DNA structure, and different DNA repair processes under the effects of different mutagens is discussed on the basis of the experimental results. 18 D. Bellincampi, G. Gualandi and G. Morpurgo, Istituto Superiore di Sanit~ di R o m a and Istituto dell'Orto Botanico di R o m a (Italy) Relationship b e t w e e n m u t a t i o n and non-disjunction in A. nidulans A liquid quantitative test [1] was employed to detect mitotic non-disjunction and gene mutation induced b y chemicals using the diploid strain P~ of A. nidulans. The liquid test permits to study these genetic damages on conidia at different physiological conditions (quiescent or germinating conidia). T w o classes of agents inducing non-disjunction may be detected. The first causes all possible types of genetic damages either on quiescent or germinating conidia and acts presumably at the DNA level. The c o m p o u n d s that we have found to induce either non-disjunction or point mutation were MMS, 4NQO and HN2. The chemicals enclosed in the second class induce non-disjunction at high level only on germinating conidia and do n o t cause p o i n t mutation. In the last class the target of chemical is a structure different b y DNA b u t involved in the cellular division. The agents enclosed in this class were: Benomyl which interferes with the spindle microtubules [ 2 ] , Amphotericin B which complexes the sterols altering the membrane structure [3], p-fluorophenylalanine, an analogue of phenylalanine which is incorporated in the proteins, and ethyl alcohol which inhibits the mitosis in a n o t clear w a y [4]. References 1 M o r p u r g o , G., D. B e l l i n c a m p i , G. G u a l a n d i , L. B a l d i n e n i a n d O. Serlupi, E n v i r o n . H e a l t h Perspec~.. 1 9 7 9 , in press. 2 Kappas, A., E.S.G. Geottrgopoulos a n d A.C. Hastie, J. Gen. Microbiol., 67 ( 1 9 7 1 ) 371. 3 H a m i l t o n - M i l l e r , J . M . T . , A d v a n c . A p p L M i c r o b i o l . , 17 ( 1 9 7 4 ) 1 0 9 - - 1 3 4 4 Ha~sanyi, Z., I.A. G r a n e k a n d D.W.R. M a c K e n z i e , M u t a t i o n Res., 4 8 ( 1 9 7 7 ) . W o r k p a r t i a l l y g r a n t e d b y C.E.E. ( c o n t r a c t N. 177-77-1 E N V . D.