Relationships between the most commonly used Dictyostelium strains. (a) Simplified genealogical tree showing the relationships between common laboratory strains derived from NC4. The branch marked 'Ax3' is more complex than shown here: sub-lineages have been given the names KAx3 and Ax4. The auxotrophic strain DH1 was engineered in an 'Ax3' background, and JH10 from 'Ax4.' (b) Plaque morphologies. Cells were plated clonally in association with Klebsiella aerogenes on SM agar. Plaques were photographed after 4 days. Small DH1 plaques are indicated with arrowheads. Variation in diameter is a function of the rate of feeding and of the motility of the amoebae. Where the bacteria are cleared the amoebae aggregate in streams; this process had not yet begun in the slow-growing DH1 plaques. (c) Fruiting bodies. Wild type cells - in this instance NC4(Dee) - form larger, more robust fruiting bodies than axenic mutants.