Species recognition in social amoebae

Area of Science:

• Cellular Biology
• Evolutionary Biology
• Genetics

Background:

• Aggregative multicellularity in social amoebae depends on conspecific recognition.
• The mechanisms and evolutionary origins of species recognition in social amoebae are not fully understood.

Purpose of the Study:

• To investigate the genetic basis of species recognition in the social amoebae *Dictyostelium purpureum* and *Dictyostelium discoideum*.
• To explore the evolutionary relationship between species recognition and cell-type differentiation.

Main Methods:

• Heterologous gene expression in *D. discoideum*.
• Analysis of gene structure and polymorphism in *D. purpureum*.
• Comparative genomics of social amoebae.

Main Results:

• A single *D. purpureum* gene enabled *D. discoideum* to form chimeric fruiting bodies with *D. purpureum*.
• This gene and its bidirectional partner are highly polymorphic in wild isolates, correlating with lack of chimerism.
• These genes are structurally similar to *D. discoideum*'s tgrB1/C1 genes, involved in clonal discrimination.

Conclusions:

• The identified *D. purpureum* tgr genes form a species recognition system with high precision, capable of discriminating between clones.
• The evolution of these precise allorecognition systems coincides with the development of prestalk cells in certain social amoebae clades.