PPRAS1,PPRAS2 AND PPRAP1 GENES, MEMBERS OF A RAS GENE FAMILY FROM THETRUE SLIME-MOLD PHYSARUM-POLYCEPHALUM, ARE DEVELOPMENTALLY-REGULATED

The expression patterns of two true ras genes, Ppras1 and Ppras2, and one rap gene, Pprap1, were examined in four Physarum polycephalum deve lopmental stages: uninucleate amoebae, plasmodia (multinucleate syncyt ia), spherules (a vegetative, dormant stage) and fruiting bodies. Ppra s1 and Pprap1 are expressed in all stages examined with the maximum le vels of their transcripts in amoebae and fruiting bodies, respectively , and the minimum levels in plasmodia, whereas the Ppras2 transcript i s only detectable in amoebae and fruiting bodies. The results obtained indicate that P. polycephalum is an organism possessing a development ally regulated I as gene family and presents a convenient system to st udy the role of ras/rap genes in control of growth and differentiation of lower eukaryotic organisms. (C) 1997 Academic Press Limited.