Development in Slime Moulds

Abstract

the slime moulds or mycetozoa are a unique group of eukaryotic microorganisms whose usual life cycle is comprised of an animal-like (protozoan) feeding stage and a spore-producing stage which bears resemblances to fungi. The group includes a large number of species which are placed in four distinct groups (Lechevalier, 1978). The life cycles of all types show basic similarities with the vegetative stage represented by an amoebal form, or myxamoeba which then develops into a multinucleate or multicellular stage depending on the organism (figure 6.1). The truly reproductive stage involves the formation of a fruit body bearing spores which provide the start of a new cycle. Two species have been the centre of very intensive research; Physarum polycephalum which is an acellular slime mould or Myxomycete, andDictyostelium discoideum a cellular slime mould and thus a representative of the Acrasiales. These two organisms are used extensively by cell biologists and developmental biologists exploiting some of their individual features as model systems. As a consequence microbiologists interested in developmental processes in other types of organisms can benefit from this broad area of research utilising the knowledge in an understanding of their own systems. Although this chapter will deal primarily with the developmental cycles of Physarum polycephalum and Dictyostelium discoideum, it should be realised that other species of these genera and other slime moulds are now being studied more widely.