Electroporation of Physarum polycephalum

The protist Physarum polycephalum is a convenient system for studies of molecular and cellular biology of fundamental eukaryotic processes, including DNA replication, mitotic regulation, single-cell development, the cytoskeleton, and motility. The life cycle of this acellular slime mold exhibits a variety of developmental transitions, and the two vegetative cell types, amoeba and plasmodium, alternate via a sexual cycle (1 ). The plasmodium is a multinucleate syncytium, in which the nuclei transit the mitotic cycle in perfect natural synchrony. This is convenient for analysis of the relative timing of biochemical events in the unperturbed mitotic cycle, since huge quantities of material can be isolated from multiple stages of consecutive mitotic cycles. The haploid amoebae are by contrast uninucleate and, in addition to vegetative growth, are capable of acting as gametes in sexual crosses, giving rise to diploid plasmodia. Meiosis occurs when the plasmodium sporulates, and the spores hatch to yield haploid amoebae. Mutations in gadA , tightly linked to the major mating-type locus matA , permit asexual development of haploid plasmodia (“selfing”) from clones of haploid amoebae (2 ). Thus, methods of classical genetic analysis and mutant isolation in Physarum are straightforward.