Cellular slime molds

Cooperation and conflict in the life cycle

Picture courtesy:Sathiyanarayanan Manivannan, Graduate student, OSU.

Cellular slime molds are soil-dwelling microorganisms and display an interesting life cycle shifting between unicellular and multicellular forms. As unicellular amoebae, they feed on bacteria and retain their single cell identity as long as food is abundant. On starvation, hundreds to thousands of amoebae initiate a chemotactic signal-relay using either polyketide or peptidic and other unidentified signalling molecules and forms a multicellular slug. Cells at the anterior end of the slug differentiates to a dead stalk of the fruiting body while the rest of the cells are encapsulated as spores held on top of the stalk. In favorable circumstances, spores disperse establishing a new territory. As the identity of the cell is maintained throughout the life cycle, they are called cellular slime molds.

Slime molds as a model system

Only in the complete absence of growth or cell division, multi-cellular development begins in slime molds, thus allowing one to track each process independently of the other. Just two cell differentiated cell types make up this organism and they include the dead stalk and the dormant spores. Various molecular tools are established in Dictyostelium and with an array of mutants impaired in different developmental processes it is possible to study many fundamental problems in biology. Also, there is an earnest attempt to sequence the genome of different slime mold species and this will pave way for exciting research ahead. For a detailed description of cellular slime molds, please go to www.dictybase.org